Coal geology and assessment of coal resources and reserves in the Powder River Basin, Wyoming and Montana
<p><span>This report presents the final results of the first assessment of both coal resources and reserves for all significant coal beds in the entire…
Public-domain full text preserved in the Mountain Man Mining Library. Original source: pubs.usgs.gov.
U.S. Department of the Interior U.S. Geological Survey Professional Paper 1809 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana
Cover: Photograph showing surface coal mining in the Powder River Basin.
Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana By James A. Luppens, David C. Scott, Jon E. Haacke, Lee M. Osmonson, and Paul E. Pierce Professional Paper 1809 U.S. Department of the Interior U.S. Geological Survey
U.S. Department of the Interior SALLY JEWELL, Secretary U.S. Geological Survey Suzette M. Kimball, Acting Director U.S. Geological Survey, Reston, Virginia: 2015 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment, visit http://www.usgs.gov or call 1-888-ASK-USGS. For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprod To order this and other USGS information products, visit http://store.usgs.gov Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. Suggested citation: Luppens, J.A., Scott, D.C., Haacke, J.E, Osmonson, L.M., and Pierce, P.E., 2015, Coal geology and assessment of coal resources and reserves in the Powder River Basin, Wyoming and Montana: U.S. Geological Survey Professional Paper 1809, 218 p., http://dx.doi.org/10.3133/pp1809. Library of Congress Cataloging-in-Publication Data Luppens, James A. (James Alan), 1946- Coal geology and assessment of coal resources and reserves in the Powder River Basin, Wyoming and Montana / by James A. Luppens, David C. Scott, Jon E. Haacke, Lee M. Osmonson, and Paul E. Pierce. pages cm. -- (Professional paper ; 1809) Includes bibliographical references and index. ISBN 978-1-4113-3875-3 (pbk. : alk. paper) 1. Coal reserves--Powder River Basin (Wyo. and Mont.) 2. Coal--Geology--Powder River Basin (Wyo. and Mont.) I. Title. TN805.W8L87 2015 553.2'4097871--dc23 2015013801 ISSN 2330-7102 (online) ISSN 1044-9612 (print)
Contents Abstract 1 Introduction 1 Approach and Objectives 2 Geologic Setting 3 Coal Fields 4 Influence of Geologic Conditions on Coal Mining 4 Coal Quality 5 Previous and Current Coal Mining 6 Coal Lease Areas 7 Previous Coal Resource Estimates 8 Previous Coal Bed Nomenclature 8 Methodology 9 Phase One (Data Collection and Editing) 9 Data Collection 9 Phase Two (Modeling) 10 Coal Bed Correlations 10 Coalbed Modeling 11 Restrictions to Mine Models 12 Factors Affecting Extraction of Coal Resources 13 Airports 14 Alluvial Valley Floors 14 Archaeological Areas 14 Coalbed Methane 14 Dwellings and Buildings 15 Federal Land Systems 15 Historic Lands and Sites 15 Oil and Gas Development 15 Pipelines 16 Power Lines 16 Railroads 16 Rivers, Lakes, and Streams 16 Roads 16 State Lands and Trusts 17 Towns 17 Phase Three (Assessment of Resources and Reserves) 17 Coal Bed Assessment 17 Wasatch Formation Coal Beds 18 Upper Healy and Healy/Lower Ulm Coal Beds 18 Murray Coal Bed 18 Ucross Coal Bed 18 Upper Felix, Felix, and Lower Felix Coal Beds 19 Fort Union Formation Coal Beds 19 Roland (Upper Rider), Roland (Lower Rider), Roland (Baker), and Roland (Taff) Coal Beds 19 Upper Smith and Smith Coal Beds 20
Anderson Upper Rider, Anderson Lower Rider, Anderson, and Lower Anderson Coal Beds 20 Dietz 1, Dietz 2, Dietz 3, and Dietz 4 Coal Beds 21 Upper Canyon/Cox, Canyon, and Lower Canyon Coal Beds 22 Upper Ferry and Ferry Coal Beds 22 Werner/Cook Coal Bed 22 Upper Otter and Otter Coal Beds 22 Gates/Wall Coal Bed 23 Pawnee Coal Bed 23 Brewster-Arnold Coal Bed 23 Odell Coal Bed 23 Cache Coal Bed 23 A Zone Coal Bed 23 Upper Rosebud and Rosebud/Knobloch Coal Beds 24 Calvert Coal Bed 24 McKay/Nance and Lower McKay Coal Beds 24 Flowers-Goodale Coal Bed 24 Upper Witham and Robinson/Witham Coal Beds 25 Roberts/Terret Coal Bed 25 Burley Coal Bed 25 Upper Stag and Lower Stag Coal Beds 25 Coal Bed Cross Sections 25 In-Place Coal Resource Volumetrics 26 Perspectives on Environments of Deposition 27 Surface Coal Resource Assessment 29 Surface Mine Modeling 29 Geologic Aspects of Surface Mine Model Development 29 Modeling Stratigraphic Sequence for Surface Mining 30 Regional Surface Mine Modeling 32 Surface Mine Model Design Assumptions 32 Surface Mine Plant Facilities 33 Surface Mine Reclamation 34 Surface Mine Supplies and Utilities 34 Surface Mine Reserve and Recoverable Resource Evaluation Results 34 Determination of Reserves 34 Gillette Coal Field Assessment Area 34 Northern Wyoming PRB Assessment Area 35 Montana PRB Assessment Area 35 Combined PRB Reserve and Recoverable Resource Summary 36 Underground Coal Resource Assessment 37 Underground Mine Model Design 37 Underground Mine Layout Design 37 Surface Mine Plant 38 Underground Mine Plant 38 Underground Mine Development Excavation 38 Longwall Panel and Pillar Recovery 38 Underground Coal Resources Results 39 Conclusions 39 Acknowledgments 40 References Cited 40 Glossary 47
Figures
1. Map showing location of the Powder River Basin, Wyoming and Montana 53
2. Map showing location of individual assessment areas in the Powder River Basin, Wyoming and Montana 54
3. Map showing structure contours drawn on the top of the Tullock Member of the Fort Union Formation 55
4. Map showing generalized surface geology of the Powder River Basin, Wyoming and Montana 56
5. Generalized stratigraphic column for the Powder River Basin, Wyoming and Montana 57
6. Map showing location of coal fields in the Powder River Basin, Wyoming and Montana 58
7. Map showing location of significant clinker in the Powder River Basin, Wyoming and Montana 59
8. West-east cross section A-A' showing subsurface distribution of significant coal beds through the southern part of the Powder River Basin, Wyoming 60
9. West-east cross section B-B' showing subsurface distribution of significant coal beds through the central part of the Powder River Basin, Wyoming 62
10. North-south cross section C-C' showing subsurface distribution of significant coal beds through the Powder River Basin, Wyoming and Montana 61
11. Map showing approximate location of faults within the Powder River Basin, Wyoming and Montana 63
12. Map showing locations of mines, lease areas, and average coal quality basis within the Powder River Basin, Wyoming and Montana 64
13. Coal bed and coal zone names used in this assessment and previous publications in the Powder River Basin, Wyoming and Montana 65
14. Flow chart showing generalized U.S. Geological Survey methodology used for coal resource and reserve assessment 66
15. Map showing mines and nonproprietary drill holes and paleochannels within the Anderson coal bed in the Powder River Basin, Wyoming and Montana 67
16. Cross section A-A' showing correlations used in the U.S. Geological Survey Miscellaneous Investigations Series Map I-1959-D by Molnia and Pierce (1992) 68
17. Cross section B-B' showing comparison of coal bed correlations made in the Gillette coal field report to the U.S. Geological Survey Miscellaneous Investigations Series Map I-1959-D by Molnia and Pierce (1992) 69
18. Isopach map showing combined thickness of the Smith, Anderson, and Canyon coal beds and areas of thin or absent coal ("want area" after Flores and others, 2010) within the Powder River Basin, Wyoming and Montana 70
19. Map showing land-use restrictions in the Powder River, Wyoming and Montana 71
20. Map showing coal mineral estate ownership in the Powder River Basin, Wyoming and Montana 72
21. Illustration showing the effect of coal-bed depth upon restricted resource because of mine-pit highwall setback requirements 73
22. Map showing location of areas of low, moderate, and high coalbed methane potential in the Powder River Basin, Wyoming and Montana 74
23. Coal bed stratigraphy, original and available resources, and maximum and average thicknesses for coal beds in the Powder River Basin, Wyoming and Montana 75
24. Isopach map of the Upper Healy coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 76
25. Map showing depth to the top of the Upper Healy coal bed within the Powder River Basin 77
26. Isopach map of the Healy/Lower Ulm coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 78
27. Map showing depth to the top of the Healy/Lower Ulm coal bed within the Powder River Basin 79
28. Isopach map of the Murray coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 80
29. Map showing depth to the top of the Murray coal bed within the Powder River Basin 81
30. Isopach map of the Ucross coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 82
31. Map showing depth to the top of the Ucross coal bed within the Powder River Basin 83
32. Isopach map of the Upper Felix coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 84
33. Map showing depth to the top of the Upper Felix coal bed within the Powder River Basin 85
34. Isopach map of the Felix coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 86
35. Map showing depth to the top of the Felix coal bed within the Powder River Basin 87
36. Isopach map of the Lower Felix coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 88
37. Map showing depth to the top of the Lower Felix coal bed within the Powder River Basin 89
38. Isopach map of the Roland (Upper Rider) coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 90
39. Map showing depth to the top of the Roland (Upper Rider) coal bed within the Powder River Basin 91
40. Isopach map of the Roland (Lower Rider) coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 92
41. Map showing depth to the top of the Roland (Lower Rider) coal bed within the Powder River Basin 93
42. Isopach map of the Roland (Baker) coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 94
43. Map showing depth to the top of the Roland (Baker) coal bed within the Powder River Basin 95
44. Isopach map of the Roland (Taff) coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 96
45. Map showing depth to the top of the Roland (Taff) coal bed within the Powder River Basin 97
46. Isopach map of the Upper Smith coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 98
47. Map showing depth to the top of the Upper Smith coal bed within the Powder River Basin 99
48. Isopach map of the Smith coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 100
49. Map showing depth to the top of the Smith coal bed within the Powder River Basin 101
50. Isopach map of the Anderson Upper Rider coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 102
51. Map showing depth to the top of the Anderson Upper Rider coal bed within the Powder River Basin 103
52. Isopach map of the Anderson Lower Rider coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 104
53. Map showing depth to the top of the Anderson Lower Rider coal bed within the Powder River Basin 105
54. Isopach map of the Anderson coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 106
55. Map showing depth to the top of the Anderson coal bed within the Powder River Basin 107
56. Isopach map of the Lower Anderson coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 108
57. Map showing depth to the top of the Lower Anderson coal bed within the Powder River Basin 109
58. Isopach map of the Dietz 1 coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 110
59. Map showing depth to the top of the Dietz 1 coal bed within the Powder River Basin 111
60. Isopach map of the Dietz 2 coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 112
61. Map showing depth to the top of the Dietz 2 coal bed within the Powder River Basin 113
62. Isopach map of the Dietz 3 coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 114
63. Map showing depth to the top of the Dietz 3 coal bed within the Powder River Basin 115
64. Isopach map of the Dietz 4 coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 116
65. Map showing depth to the top of the Dietz 4 coal bed within the Powder River Basin 117
66. Isopach map of the Upper Canyon (Cox) coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 118
67. Map showing depth to the top of the Upper Canyon (Cox) coal bed within the Powder River Basin 119
68. Isopach map of the Canyon coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 120
69. Map showing depth to the top of the Canyon coal bed within the Powder River Basin 121
70. Isopach map of the Lower Canyon coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 122
71. Map showing depth to the top of the Lower Canyon coal bed within the Powder River Basin 123
72. Isopach map of the Upper Ferry coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 124
73. Map showing depth to the top of the Upper Ferry coal bed within the Powder River Basin 125
74. Isopach map of the Ferry coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 126
75. Map showing depth to the top of the Ferry coal bed within the Powder River Basin 127
76. Isopach map of the Werner/Cook coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 128
77. Map showing depth to the top of the Werner/Cook coal bed within the Powder River Basin 129
78. Isopach map of the Upper Otter coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 130
79. Map showing depth to the top of the Upper Otter coal bed within the Powder River Basin 131
80. Isopach map of the Otter coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 132
81. Map showing depth to the top of the Otter coal bed within the Powder River Basin 133
82. Isopach map of the Gates/Wall coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 134
83. Map showing depth to the top of the Gates/Wall coal bed within the Powder River Basin 135
84. Isopach map of the Pawnee coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 136
85. Map showing depth to the top of the Pawnee coal bed within the Powder River Basin 137
86. Isopach map of the Brewster-Arnold coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 138
87. Map showing depth to the top of the Brewster-Arnold coal bed within the Powder River Basin 139
88. Isopach map of the Odell coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 140
89. Map showing depth to the top of the Odell coal bed within the Powder River Basin 141
90. Isopach map of the Cache coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 142
91. Map showing depth to the top of the Cache coal bed within the Powder River Basin 143
92. Isopach map of the A Zone coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 144
93. Map showing depth to the top of the A Zone coal bed within the Powder River Basin 145
94. Isopach map of the Upper Rosebud coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 146
95. Map showing depth to the top of the Upper Rosebud coal bed within the Powder River Basin 147
96. Isopach map of the Rosebud/Knobloch coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 148
97. Map showing depth to the top of the Rosebud/Knobloch coal bed within the Powder River Basin 149
98. Isopach map of the Calvert coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 150
99. Map showing depth to the top of the Calvert coal bed within the Powder River Basin 151
100. Isopach map of the McKay/Nance coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 152
101. Map showing depth to the top of the McKay/Nance coal bed within the Powder River Basin 153
102. Isopach map of the Lower McKay coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 154
103. Map showing depth to the top of the Lower McKay coal bed within the Powder River Basin 155
104. Isopach map of the Flowers-Goodale coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 156
105. Map showing depth to the top of the Flowers-Goodale coal bed within the Powder River Basin 157
106. Isopach map of the Upper Witham coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 158
107. Map showing depth to the top of the Upper Witham coal bed within the Powder River Basin 159
108. Isopach map of the Robinson/Witham coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 160
109. Map showing depth to the top of the Robinson/Witham coal bed within the Powder River Basin 161
110. Isopach map of the Roberts/Terret coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 162
111. Map showing depth to the top of the Roberts/Terret coal bed within the Powder River Basin 163
112. Isopach map of the Burley coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 164
113. Map showing depth to the top of the Burley coal bed within the Powder River Basin 165
114. Isopach map of the Upper Stag coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 166
115. Map showing depth to the top of the Upper Stag coal bed within the Powder River Basin 167
116. Isopach map of the Lower Stag coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin 168
117. Map showing depth to the top of the Lower Stag coal bed within the Powder River Basin 169
118. Pie diagram showing tonnages and percentages of individual coal beds in relation to the total 1.16 trillion short tons of original resources in the Powder River Basin, Wyoming and Montana 170
119. Isopach map of the Flowers-Goodale coal bed showing extent of resources at least 1.0 foot thick and location of lineaments described by Jones, 2010a, in the Powder River Basin, Wyoming and Montana 171
120. Isopach map of the Roberts/Terret coal bed showing extent of resources at least 1.0 foot thick and location of lineaments described by Jones, 2010a, in the Powder River Basin, Wyoming and Montana 172
121. Isopach map of the Smith, Anderson, and Canyon coal beds showing extent of resources at least 5 feet thick and location of lineaments described by Jones, 2010a in the Powder River Basin, Wyoming and Montana 173
122. Isopach map showing interburden thickness between the Anderson and Canyon coal beds in the Gillette coal field and location of lineaments described by Jones, 2010a in the Powder River Basin, Wyoming 174
123. Generic cost curve showing 12.8 billion short tons (BST) reserve estimate at $13.20 per ton for the Powder River Basin, Wyoming and Montana 175
124. Map showing areal extent for the composite stripping ratio of the Roland (Baker), Smith, Upper Anderson, Anderson, Dietz, and Canyon coal beds in the Gillette coal field, Wyoming Powder River Basin 176
125. Cost curve showing reserve estimates at $10.47 per short ton (as of January 2007) and $14.00 per short ton (as of March 2008) for the Gillette coal field, Wyoming 177
126. Map showing areal extent for the composite stripping ratio of the Roland (Baker), Smith, Anderson, Dietz 3, Canyon, Lower Canyon, and Werner/Cook coal beds where the stripping ratios are from 1:1 to 10:1, thicknesses are equal to at least 5.0 feet, and the overburden is less than or equal to 500 feet thick, in the Wyoming Powder River Basin 178
127. Cost curve showing 1.5 billion ton reserve estimate at $9.30 per short ton (as of February 2010) for the Northern Wyoming Powder River Basin assessment area 179
128. Map showing areal extent for the composite stripping ratio of the Roland (Baker), Smith, Anderson, Dietz 2, and Dietz 3 coal beds where the stripping ratios are from 1:1 to 10:1, thicknesses are equal to at least 5.0 feet, and the overburden is less than or equal to 500 feet thick, in the Montana Powder River Basin 180
129. Map showing areal extent for the stripping ratio of the Canyon coal bed where the stripping ratios are from 1:1 to 10:1, thicknesses are equal to at least 5.0 feet, and the overburden is less than or equal to 500 feet thick, in the Montana Powder River Basin 181
130. Map showing areal extent for the stripping ratio of the Werner/Cook coal bed where the stripping ratios are from 1:1 to 10:1, thicknesses are equal to at least 5.0 feet, and the overburden is less than or equal to 500 feet thick, in the Montana Powder River Basin 182
131. Map showing areal extent for the stripping ratio of the Pawnee coal bed where the stripping ratios are from 1:1 to 10:1, thicknesses are equal to at least 5.0 feet, and the overburden is less than or equal to 500 feet thick, in the Montana Powder River Basin 183
132. Map showing areal extent for the stripping ratio of the Rosebud/Knobloch coal bed where the stripping ratios are from 1:1 to 10:1, thicknesses are equal to at least 5.0 feet, and the overburden is less than or equal to 500 feet thick, in the Montana Powder River Basin 184
133. Map showing areal extent for the stripping ratio of the Flowers-Goodale coal bed where the stripping ratios are from 1:1 to 10:1, thicknesses are equal to at least 5.0 feet, and the overburden is less than or equal to 500 feet thick, in the Montana Powder River Basin 185
134. Graph showing cost curve for the Montana Powder River Basin assessment area showing estimated recoverable coal resources compared to sales price per ton of coal 186
135. Bar graph showing resource and reserve summary in the Powder River Basin, Wyoming and Montana 187
136. Graph showing cumulative cost curve for the Powder River Basin, Wyoming and Montana (Gillette coal field, Northern Wyoming Powder River Basin, and Montana Powder River Basin assessment areas) 188 Tables
1. 2012 and cumulative coal production from the Powder River Basin, Wyoming and Montana 191
2. Typical proximate analysis on an as-received basis of coal from mines in the Powder River Basin, Wyoming and Montana 192
3. Typical proximate analysis on an as-received basis of coal beds reporting sodium as percent of ash, percent sulfur, percent ash, and calorific value, in coal beds in the Wyoming Powder River Basin compared to the Montana Powder River Basin 193
Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by reliability category for the Powder River Basin, Wyoming and Montana 194
5. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by overburden depth for the Powder River Basin, Wyoming and Montana 198
6. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons, by coal ownership categories for the Powder River Basin, Wyoming and Montana 204
7. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by assessment area 208
8. Summary of coal resources by reliability, depth, ownership, and assessment area categories in the Powder River Basin, Wyoming and Montana 214
9. Summary of resources by reliability categories for all 47 coal beds assessed in the Powder River Basin and comparison of reliability of previous assessment of the Wyodak-Anderson zone in the Gillette coal field to the current Powder River Basin assessment 215
10. Example of a regional mine model stratigraphic sequence used in the economic evaluation of the Northern Wyoming Powder River Basin assessment area, River Wyoming 215
11. Estimated impacts of compositing the originally excluded shale, pyrite, and other high-ash parting material with the coal analyses for the USGS-1 core hole from the Lake DeSmet coal area, Wyoming 216
12. Coal resources and reserves for beds greater than or equal to 5.0 feet thick in each assessment area in the Powder River Basin, Wyoming and Montana 216
13. Underground resources for coal beds 10-20 feet thick and greater than 500 feet deep in the Powder River Basin, Wyoming and Montana 217
Conversion Factors Multiply By To obtain Length foot (ft) meter (m) mile (mi) kilometer (km) square mile (mi2) square kilometer (km2) square feet (ft2) square meters (m2) Mass pounds (lbs) kilograms (kg) short tons (2,000 lbs) 0.90718474 metric tons (2,204.6 lbs) Vertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD 88). Horizontal coordinate information is referenced to the Universal Transverse Mercator (UTM) map projection, using the following parameters: map units meters; zone 13; datum NAD83; and spheroid Clarke, 1866. Abbreviations and Acronyms Used in This Report BST billion short tons Btu/lb British thermal unit per pound CARS coal availability and resource studies CBM coalbed methane DRB demonstrated reserve base EIA U.S. Energy Information Administration ERR estimated recoverable reserve base Esri Environmental Systems Research International ft feet ft2 square feet hr hour GIS geographic information system in inch MBMG Montana Bureau of Mines and Geology mi mile mi2 square mile MST million short tons MST/yr million short tons per year MTPRB Montana Powder River Basin assessment area NCRA National Coal Resource Assessment NCRDS USGS National Coal Resources Database System NWPRB Northern Wyoming Powder River Basin assessment area PRB Powder River Basin (both Wyoming and Montana)
PRLAs preference right lease applications RAP resource allocation planning SMCRA Surface Mining Control and Reclamation Act SO2/lb sulfur dioxide per pound SWPRB Southwestern Powder River Basin assessment area USBLM U.S. Bureau of Land Management USFS U.S. Forest Service USGS U.S. Geological Survey UTM Universal Transverse Mercator WSGS Wyoming State Geological Survey WOGCC Wyoming Oil and Gas Conservation Commission yd3 cubic yards yr year
Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana By James A. Luppens, David C. Scott, Jon E. Haacke, Lee M. Osmonson, and Paul E. Pierce Abstract This report presents the final results of the first assess ment of both coal resources and reserves for all significant coal beds in the entire Powder River Basin, northeastern Wyoming and southeastern Montana. The basin covers about 19,500 square miles, exclusive of the part of the basin within the Crow and Northern Cheyenne Indian Reservations in Montana. The Powder River Basin, which contains the largest resources of low-sulfur, low-ash, subbituminous coal in the United States, is the single most important coal basin in the United States. In 2012, almost 420 million short tons were produced from this basin, which was about 42 percent of the total coal production in the United States. Prior resource assessments relied on net coal thickness maps for only selected beds. Although net thickness maps are sufficient for estimating in-place (remaining) resources, the mapping of all individual beds is necessary for conduct ing economic studies to determine the coal reserve base for the Powder River Basin. The coal reserve base includes those resources that are currently (October 2014) economic (reserves), but also may encompass those parts of a resource that have a reasonable potential for becoming economically available. Thus, the coal reserve base provides a more realistic estimate of the portion of in-place resources that are poten tially recoverable, which is important from a national energy standpoint. A key to the success of this current assessment was incorporating as much data as practical from the recent, exten sive coalbed methane development in the basin. The interpre tation of these new data proved critical to the development of a comprehensive geologic model needed for estimating coal resources and reserves in the Powder River Basin. A total of 29,928 drill holes were used for this assessment, of which 21,393 are in the public domain. The U.S. Geological Survey used a geology-based assess ment methodology to estimate an original coal resource of about 1.16 trillion short tons for 47 coal beds in the Powder River Basin; in-place (remaining) resources are about 1.15 trillion short tons. The most significant resources are within the Tertiary (Paleocene) Tongue River Member of the Fort Union Formation and include the Roland (Baker, 1929), Smith, Anderson, Dietz 3, Canyon, Lower Canyon, Werner/Cook, Otter, Gates/ Wall, Rosebud/Knobloch, Flowers-Goodale, and Roberts/Terret coal beds. These resources represent about 944 billion short tons (81.5 percent) of the total 1.16 trillion short tons of original coal resource estimated for the Powder River Basin. Not all 47 coal beds were included in the mining econom ics evaluation. Only those beds that exceeded 5.0 ft in thick ness and had a significant areal extent with a stripping ratio of 10:1 or less were included. A total of 162 billion short tons of recoverable coal resources (coal reserve base) are estimated at a 10:1 stripping ratio or less. An estimated 25 billion short tons of that coal reserve base met the definition of reserves, which are resources that can be economically produced at or below the current sales price at the time of the evaluation. This reserve estimate does not mean that the total amount of coal left in the Powder River Basin could be produced by surface mining technologies. The costs of mining and coal sales prices are not static as both tend to increase over time if supported by demand. If future market prices exceed mining costs, portions of the coal reserve base would be elevated to reserve status (and the converse). There are no active underground mining operations in the Powder River Basin, nor are any anticipated in the foresee able future. However, there are significant deeper coal resources in the basin that could be produced with current underground mining technologies. Therefore, a preliminary estimate of coal with thicknesses amenable for longwall mining was conducted. The total underground coal resource in coal beds 10-20 feet thick is estimated at 304 billion short tons. Introduction The U.S. Geological Survey (USGS) is responsible for providing objective scientific information to support decisions regarding land management, environmental quality, energy, and strategic policy. Therefore, the USGS periodically assesses the Nation's endowment of various energy resources, including coal. The objective of the United States Coal Resources and
2 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Reserves Assessment Project is to conduct regional-scale coal resource1 and coal reserve assessments of coal beds in major coal basins. Coal resource and reserve estimates are essential for planning local, State, and Federal energy and land-use pol icy decisions now and for the foreseeable future. These esti mates are also necessary to determine possible socioeconomic effects on a region as coal resources and reserves are devel oped and approach depletion (Luppens and others, 2008). From 1999 to 2009, the USGS completed the first digital National Coal Resource Assessment (NCRA) of in-place (remaining) coal resources (Pierce and Dennen, 2009); however, these estimates did not provide all the information needed for resource planning. Calculations of the portion of in-place coal resources that are economically recoverable (coal reserves) are equally important (Luppens and others, 2009). Since the NCRA study, USGS methodology to calcu late resources and reserves has been refined to take advantage of improvements in computer hardware, geologic and mine model software, and availability of data. As a result, the scope of coal resource and especially reserve assessment capabili ties has grown in geographic size from a single topographic quadrangle to entire coal fields and geologic basins. The first U.S. coal basin evaluated in the coal assess ment project is the Powder River Basin (PRB) Wyoming and Montana (fig. 1). In this report, the abbreviation PRB refers to the entire Powder River Basin (Wyoming and Montana); Wyoming PRB refers only to the Wyoming portion of the basin, and Montana PRB refers only to the Montana portion of the basin. The PRB contains some of the most significant deposits of low-sulfur, low-ash, subbituminous coal in the world (Molnia and Pierce, 1992). In 2012, coal production from 16 mines in the basin totaled almost 420 million short tons (MST) (42 percent of the total coal production in the United States), making it the single most important coalproducing basin in the Nation (table 1). About 388 MST (93 percent of the total PRB coal production) came from the Gillette coal field, located in the eastern part of the Wyoming PRB (fig. 2, table 1). There is often confusion regarding the use of the terms coal resources and coal reserves as they relate to assessments. Although the two terms have been used interchangeably, there are significant differences between the definitions. Coal resources include those in-place tonnage estimates deter mined by summing the volumes for identified resources and hypothetical resources, using coal zones of a minimum thick ness and within certain depth limits (commonly 0-2,000 feet [ft] deep) (Pierce and Dennen, 2009). Coal reserves are a sub set of coal resources and are considered economically minable at the time of classification (Wood and others, 1983). Results presented in this report include not only an assessment of coal resources and reserves, but also the most current and comprehensive correlation of individual coal beds throughout the PRB. Other coal stratigraphers have attempted 1Technical terms used in this report requiring additional explanation are italicized when used for the first time and their definitions are given in the Glossary section at the end of the report. to correlate the entire PRB (Flores and others, 2010); however, that assessment did not include all of the Montana PRB assess ment area, nor did it include deeper coal beds in the PRB. This assessment is based on data from the entire PRB and correlates coal beds based on their stratigraphic position. The Powder River Basin is a structural and sedimentary basin that is generally defined by Tertiary-age (Paleocene) rocks that crop out along the margins of the basin. The basin covers about 19,500 square miles (mi2) exclusive of the part of the basin within the Crow and Northern Cheyenne Indian Reservations in the Montana PRB (fig. 1). The basin extends north-south from Miles City, Montana to Douglas, Wyoming; the west-east extent in the Wyoming PRB is from about Sheridan to Moorcroft and from about Decker to Broadus, in the Montana PRB (fig. 1). The PRB was divided into five geographic areas to keep databases and modeled areas to a manageable size and permit timely publication of assessment results (fig. 2). Four of those areas are in the Wyoming PRB and one is in the Montana PRB: (1) Luppens and others (2008) reported on the first assessment area, summarizing geology, coal resources, and reserves for the Gillette coal field; (2) Scott and others (2010) summarized the second assessment area and pre sented results on geology, coal resources, and reserves for the Northern Wyoming Powder River Basin assessment area (NWPRB assessment area); (3) Osmonson and others (2011) summarized the third assessment area and presented results on geology and coal resources in the Southwestern Powder River Basin assessment area (SWPRB assessment area); and (4) Haacke and others (2013) summarized the fourth assess ment area and presented results on geology, coal resources, and reserves for the Montana Powder River Basin assessment area (MTPRB assessment area). The fifth area (East Gillette coal field extension) extends east from the Gillette coal field and was evaluated for this report specifically to provide a more comprehensive mapping of coal beds below the WyodakAnderson coal zone and to complete the assessment of the entire PRB (fig. 2). This publication supersedes the four OpenFile Reports and presents estimates of coal resources and reserves for the entire PRB. Supplemental to this report are the geographic information system (GIS) data created using Environmental Systems Research International (Esri) ArcGIS (Environmental Systems Research International, 2006) that can be used to show the PRB boundary in map view along with other pertinent data layers (Kinney and others, 2015). Approach and Objectives To provide a meaningful estimate of the amount of coal that is potentially recoverable, the USGS and the former U.S. Bureau of Mines conducted initial coal availability and recoverability Studies (CARS) in the late 1980s (Luppens and others, 2009). These studies included both mine planning and economic studies that were used to derive estimates of the coal reserves for limited areas. The CARS methodology evolved
Geologic Setting 3 from single 7.5-minute quadrangle maps containing an area of about 56 square miles (mi2) (145.0 square kilometers [km2]) to entire coal fields containing greater than 2,000 mi2 (greater than 5,180 km2). These advances became feasible largely because of advances in computer hardware and software and the availability of digital information regarding geology, geog raphy, and societal data and infrastructure. One of the objectives of the USGS CARS project has been to provide data to update the U.S. Energy Information Administration (EIA) demonstrated coal reserve base (DRB), the only publicly available, nationwide summary of the quantities of minable coal conforming to a unified set of criteria (EIA, 1997). The EIA has obtained valuable accessibil ity and recoverability data for recent coal reserve estimates from the USGS coal availability studies and from the former U.S. Bureau of Mines coal recoverability studies. The EIA use of revised CARS data in New Mexico, Illinois, and Eastern Kentucky document the increasing cooperation among EIA, the U.S. Geological Survey, and State geological agencies in order to share data and coordinate efforts in their coal resource and reserve programs (EIA, 1997). Regardless of the size or generation of the particular CARS area, the methodology to estimate coal resources and reserves has remained standardized and consistent throughout the assessment process. For CARS assessments, coal beds must be correlated and modeled individually. Another key compo nent is the systematic inventory of restrictions to mining to yield the volume of coal that could be potentially recovered. Previous USGS resource assessments in the PRB have relied on the correlation of coal bed zones and overburden depths based on depth to the uppermost coal bed in a zone (for example, Ellis and others, 1999, and Flores and others, 2010). Flores and others (1999) defined a coal zone (WyodakAnderson) in the Gillette coal field that is within an interval almost 900 ft thick that consists of 11 coal beds totaling more than 200 ft thick. However, by reporting only the overburden to the top of the uppermost coal bed in a coal zone, as much as 700 ft of interburden was unaccounted for assuming a 900-ftthick coal zone and a net coal bed thickness of 200 ft. Further more, there is a significant difference in terms of the cost of mining a single 200-ft-thick coal bed compared to mining seven coal beds (ranging in thickness from 3 to 50 ft) totaling 200 ft over a 900-ft-thick stratigraphic zone. Although a methodology based on coal zone correlations is suitable for calculating net inplace resources, it does not provide the comprehensive bed by bed geometry required for a mining and economic assessment of reserve potential. Therefore, another objective of the PRB coal assessment project was developing a correlated drill-hole database used to generate a multibed model that included all individual coal beds in the Powder River Basin. Historically, the CARS project relied on interpretation of both existing oil and gas well and coal drilling data; however, because of the recent development of coalbed methane (CBM) in the PRB, an abundance of new data are now available. The interpretation of these new data proved critical to the develop ment of a comprehensive geologic model needed for calculat ing coal resources and reserves in the PRB. The principal objectives of this assessment are as follows: Update the stratigraphic database, correlate individual coal beds, and unify coal bed names throughout the PRB. Develop a comprehensive, multi-coal bed geological model for the PRB with the geological assurance to support regional resource and reserve estimates. Complete an economic mining evaluation that incorpo rates the environmental and technological restrictions to mining for the PRB. Summarize coal resources and reserves for all four coal resource and reserve assessment areas in the PRB, includ ing the East Gillette extension. Supply the EIA with updated coal availability and recov erability results. Geologic Setting The geologic history of the PRB has been extensively discussed by Flores and others (2010) and Jones (2010a); there fore, an in-depth discussion of geology and depositional history of coal beds in the PRB was not a primary objective of this assessment. However, the public available downhole data gener ated during this assessment does provide a foundation for future geologic studies (Haacke and Scott, 2013). The PRB is an elongated, north-northwest-trending sedi mentary and structural basin that forms a broad asymmetric syn cline (depression) with a gently dipping east limb and a steeply dipping west limb. A structure contour map (sea level datum) drawn on top of the Tullock Member reveals the asymmetrical nature of the PRB, with the axis near the west margin of the basin (Ayers, 1986a) (fig. 3). Along the west margin of the PRB, rocks dip between 20° and 25° to the east, whereas rocks dip only about 2° to 5° to the west along the east margin of the basin (Flores and others, 1999). The synclinal axis of the basin is closer to the basin's west margin, trending north-northwest in the Wyoming PRB, and gradually turning north-northeast in the Montana PRB (Lopez, 2005) (fig. 4). In the Montana PRB, the basin is bounded by structural uplifts—the Bighorn Mountains to the west, and the Black Hills to the east—and becomes shal low to the north against the southern flank of the Miles City arch, located northeast of the PRB. Geologic strata exposed at the surface in the PRB consist almost entirely of lower Tertiary (Paleocene) Fort Union and (Eocene) Wasatch Formations with the (Oligocene) White River Formation (Oligocene) present in stream drainages (figs. 4 and 5). The Lebo Shale Member and Tullock Members of the Fort Union Formation underlie the Tongue River Member of the Fort Union and are present along the margins of the basin (fig. 4). The Wasatch Formation conformably overlies the Fort Union Formation in the center of the basin and unconformably overlies it along the basin margins. The Wasatch Formation covers about three fourths of the Wyoming PRB (fig. 4) and
4 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana extends north into the southernmost part of the Montana PRB where it crops out along topographic highs that occur between river valleys, including the Tongue River, Hanging Woman Creek, and Otter Creek drainages (Vuke and others, 2001a). The underlying Fort Union Formation is exposed along the basin margins in the Wyoming PRB and throughout most of the Montana PRB (fig. 4). The Fort Union Formation covers about one-fourth of the surface area in the PRB, mostly in the Montana PRB, and underlies the Wasatch Formation in the Wyoming PRB (fig. 4). The Fort Union Formation is composed of three members; from oldest to youngest they are the Tullock, Lebo, and Tongue River (fig. 5). Together, these members form a thick sequence of interbedded sands, gravels, silts, shales, and coals. These strata incorporate some of the thickest and most exten sive deposits of low-sulfur, low-ash, subbituminous coal in the world (Molnia and Pierce, 1992). Most of the coal is con tained in the Wyodak-Anderson coal zone in the Tongue River Member (Ellis and others, 1999). The Fort Union Formation ranges in thickness from a few hundred feet along the north margin of the Montana PRB, to approximately 4,000 ft at the Montana-Wyoming border (Jay Gunderson, Montana Bureau of Mines and Geology, written commun., 2011). Underlying the Fort Union Formation in the Montana PRB, delta-plain sands and shales of the Upper Cretaceous Hell Creek Formation (equivalent to the Lance Formation in Wyoming) grade upward into fluvial-dominated sedi ments of the lowermost Tullock Member of the Fort Union Formation (fig. 5). The top of the Hell Creek Formation is generally placed at the base of the lowest coal bed found in the Tullock Member and generally corresponds to an upward change in sedimentary character from cross-bedded to planar-bedded sandstones (Vuke and others, 2001b). The GIS layer of geology for the PRB is available using Esri ArcGIS 9.3.1 (Environmental Systems Research International, 2006) (Kinney and others, 2015). Coal Fields The Powder River Basin has been segregated into named coal fields based on geographic features or nearby towns. Pre vious investigations in the PRB often referred to areas of coal production and coal resources by coal field name; therefore, a map of all the coal fields in the PRB is included in this report (fig. 6). The Ashland, Birney-Broadus, Coalwood, Forsyth, Miles City, Mizpah, Moorhead, northward extension of the Sheridan, and Rosebud coal fields are all within the Montana PRB (Averitt, 1966; McLellan and others, 1990) (fig. 6). The Barber, Buffalo, Dry Cheyenne, Gillette, Glenrock, Little Powder River, Lost Spring, Powder River, Pumpkin Buttes, Sheridan, Spotted Horse, and Sussex coal fields are all within the Wyoming PRB (Glass, 1976) (fig. 6). The area east of the Gillette coal field is referred to as the East Gillette Extension coal field for this report (fig. 6). Influence of Geologic Conditions on Coal Mining Almost everywhere in the PRB, coal beds greater than 5 ft thick show evidence of burning. The heat from the burn ing coal on the overlying rock produces a reddish colored material known as clinker. The thickness of clinker is roughly 2-3 times the thickness of the original coal that has burned; therefore, clinker thickness can be used in exploration as a relative indicator of the approximate thickness of a coal bed. A coal bed 5-10 ft thick can produce a clinker zone 10-30 ft thick, whereas a coal bed 50 ft thick may produce a clinker zone 100-200 ft thick (Matson and Blumer, 1973). Large areas of original near-surface coal resources of the Tongue River Member of the Fort Union Formation have been destroyed by burning at the outcrop and beneath shal low cover (fig. 7). Approximately 1,000 mi2 of the surface area in the Montana PRB is affected by clinker (Coates and Heffern, 1999; Roberts and others, 1999a, b, c) (fig. 7). Roberts and others (1999c) outlined large areas of clinker in the Spring Creek and Decker Mine areas (fig. 2) affecting the Anderson, Dietz 2, and Dietz 3 coal beds. At the Rosebud Mine, near Colstrip, Montana (fig. 2), where the Rosebud and McKay beds have merged to a single bed, clinker deposits have been reported to attain a thickness of as much as 120 ft (Tudor, 1975). In the Wyoming PRB, large areas of original near-surface coal resources have been burned at their outcrop and beneath shallow cover along the east margin of the basin; approximately 750 mi2 in the Wyoming PRB is affected by clinker. The structural dip of coal beds can affect the mining method. A dip of 5° or less is optimal for both surface and underground mining. A dip of 20° or greater negatively affects both types of mining. Rocks along the west margin of the PRB dip steeply to the east (20o or more) towards the axis of the basin, whereas rocks along the east margin of the basin dip about 2-5o to the west, towards the axis of the basin. Surface coal mining has been more prevalent along the east margin of the Wyoming PRB because of the shallower dip, whereas underground mining was more prevalent along the west margin of the basin, in the area north of Sheridan, Wyoming. Figures 8 and 9 illustrate the relatively gentle dip of coal beds along the east margin of the PRB in contrast to the steeper dip of the same beds along the west margin of the basin. The stratigraphic sequence of significant coal beds in the subsurface geology of the PRB is shown in three cross sections (figs. 8-10). In the northwest portion of the Wyoming PRB and southwest portion of the Montana PRB, numerous northeasttrending faults are present (fig. 11). The faults, most of which are downthrown on the east, postdate coal bed formation. Faults shown on figure 11 are based on Ellis and others (1999) and Roberts and others (1999a, b, c), or they were identi fied during the correlation phase of this assessment from observations of stratigraphic offset between drill holes. The faults range 0.5-6.0 mi long, with displacements of as much as 140 ft (Robinson and Van Gosen, 1986). In most cases,
Geologic Setting 5 fault displacement is not much more than 100 ft. Areas where numerous high-angle faults are present are not conducive to either surface or underground mining operations. One such example in the PRB is near the abandoned Big Horn Mine (fig. 12), north of Sheridan, Wyoming, where previous underground mining in a highly faulted area has produced significant subsidence. Faults in coal beds also have an important effect on the selection of mining methods and on productivity. Major faults with vertical displacements greater than 65 ft commonly are used to delineate mine plan boundaries. Numerous minor faults are generally associated with and trend almost parallel to major faults. The adverse effects of faulting are greater on underground mining operations. A fault with a vertical displacement of 3-16 ft may not pose much of a problem in a surface mine, whereas it could be a serious impediment in underground mining (Thomas, 2002). For this report faults were not considered a restriction to mining. The method of underground mining can affect the amount of resources lost because of faulting. If the method is longwall mining, a larger resource loss will occur, because longwall operations need hazard-free runs in a designated panel of coal. Longwall panels are typically 5,000-10,000 ft in length and 750-1,500 ft in width; thus, a large, relatively unfaulted block of coal is required. If coal panels between faults are too small, then whole blocks may be lost to mining (Thomas, 2002). Coal Quality Coal quality is a major factor in its marketability and also an important input parameter for coal reserve estimations. Coal is sold based on its calorific value expressed in British thermal units per pound of coal (Btu/lb). Quality parameters, such as increased ash content that lowers the calorific value, negatively affect the operating and maintenance costs at coal-fired power plants. Therefore, coals with lower ash and sulfur content and higher calorific values command a premium selling price. A single set of typical coal quality values based on avail able data was estimated for each assessment area. The typical coal quality values were then used to determine the current freight on board (FOB) sales prices. Various trade publications publish periodic coal sales prices based on coal quality, primar ily by gross calorific value measured in Btu/lb and sulfur diox ide per pound (SO2/lb). Typically, the higher the gross calorific content and the lower the sulfur dioxide values, the higher the sales price. For example, for the week ending October, 5, 2012, the average price for Powder River Basin coal with 8,800 Btu/lb and 0.8 SO2/lb was $10.20/ton, whereas at 8,400 Btu/lb and 0.8 SO2/lb, the price was only $8.60/ton (Platts, 2012.) After the sales price for an assessed area was established, the volume of reserves could be determined. All recoverable coal resources that could be produced at or below the current sales price at the time of the evaluation (discounted cash flow (DCF) cost per ton basis), by definition, are reserves. The amendments of the Clean Air Act of 1990 (42 U.S.C. 765d) enforced emission limits at coal-fired power plants to reduce certain air pollutants, such as sulfur dioxide. Sulfur dioxide emission limits for all new coal-fired power plants built after 1976 were capped at 1.2 lbs sulfur dioxide per million Btu (U.S. Environmental Protection Agency, 1980). Any coal that could be burned and meet the sulfur dioxide emission standards for air quality (emit 0.6 lbs or less sulfur per million Btu or 1.2 lbs sulfur dioxide per million Btu) without the need for flue-gas desulfurization was designated "compliance coal," also known as low-sulfur coal (EIA, 2011). Subsequent phases of the Clean Air Act amendments have further restricted sulfur dioxide emissions. Currently, New Source Performance Standards establish uni form national Environmental Protection Agency air-emission standards that limit the amount of pollution allowed from new sources or from modified existing sources. Under New Source Performance Standards, Best Available Control Technology emission limitations are based on the maximum degree of reduction of each pollutant (U.S. Environmental Protection Agency, 2005). The current minimum Best Available Control Technology standard for sulfur dioxide emissions is 90 per cent reduction regardless of the sulfur content. Former compliance coals still have a competitive advantage because the cost to meet the 90 percent emission reductions is typically lower than higher sulfur coals. The abundance of low-sulfur and low-ash coal in the PRB has been a significant factor in the steadily growing demand for coal from this region. Coal quality information has been available since the early 1970s for most of the mines in the PRB. Figure 12 shows the average coal quality for five areas in the PRB where significant mining is current or has been proposed (averages calculated from mine averages in table 2). Table 2 summarizes coal quality for all mines in the PRB, as well as the Otter Creek lease area in the Montana PRB (fig. 12). In comparison to coal in the Wyoming PRB, coal in the Montana PRB is generally greater in sodium content (table 3). The Smith, Anderson, and Dietz 3 coal beds in the Decker and Spring Creek Mine areas generally have higher sodium con tent than the Rosebud/Knobloch coal bed in the Rosebud and Absaloka Mine areas in the Montana PRB (table 3, fig. 12). Increased sodium content in coal can cause excessive slag ging and fouling in power plants and requires boilers specifi cally designed to successfully burn coal with higher sodium contents (Thomas, 2002). In-place coal quality varies significantly within the Gillette coal field. The north, middle, and south areas (fig. 12) were defined on the basis of variations in coal quality which permitted estimates of sales price using averaged coal quality data for each area. From figure 12, the in-place coal qual ity trends by bed may be observed. The Btu is highest in the south area and lowest in the north area. Sulfur and ash gener ally increase from the south area to the north area.
6 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana In general, the apparent rank of coals in the PRB range from subbituminous C to subbituminous A. The lower rank subbituminous C coal is located primarily in the shallower part of the basin along the east margin of the PRB (Stricker and others, 2007). Subbituminous B ranked coal is found in the Sheridan and North Extension Sheridan coal fields (fig. 6) on the west side of the basin as well as at intermediate depths (Luppens, 2011). Subbituminous A ranked coal is generally found in the deeper parts of the basin (greater than 1,600 ft depth) (Luppens, 2011). Because the PRB contains subbitu minous coal, all resource and reserve volumes were calculated using an average density factor of 1,770 tons per acre foot of coal (Wood and others, 1983). Previous and Current Coal Mining In 2012, about 42 percent (420 million short tons) of the total coal production in the United States came from the PRB, distinguishing it as the most prolific coal basin in the United States (EIA, 2013). Coal production from the PRB from 1969 to 2012 has been almost 10 billion short tons (BST) (table 1). There are five areas within the PRB where current (December 2012) or previous coal mining has been signifi cant (fig. 12): (1) Colstrip, Montana (includes the Rosebud, Absaloka, and abandoned Big Sky Mine); (2) Decker, Montana (includes the Decker and Spring Creek Mines); (3) Sheridan coal field, Wyoming (includes the abandoned Big Horn Mine); (4) Gillette coal field, Wyoming (includes the Antelope, Belle Ayr, Black Thunder, Buckskin, Caballo, Coal Creek, Cordero Rojo, Dry Fork, Eagle Butte, Jacobs Ranch, North Antelope/ Rochelle, Rawhide, and Wyodak Mines); and (5) Glenrock coal field, Wyoming (includes the abandoned Dave Johnston Mine and the Stevens lease areas). On July 28, 1806, Captain William Clark of the Corps of Discovery observed coal beds as he floated down the Yellowstone River along the north margin of the Montana PRB (Moulton, 2001). Less than a year later, Manuel Lisa built a trading post at the confluence of the Bighorn and Yellowstone Rivers and used lignite coal from nearby outcrops to heat buildings during the winter months (Morgan, 1966). Despite the early discovery and use of coal in the Montana PRB, it was more than 100 years later that coal was commercially mined. In 1923, the first modern-day strip mine (Rosebud Mine) in the western United States was opened near Colstrip, Montana (fig. 2). The coal was mined by Northern Pacific Railroad Company and used to fuel steam locomotives. In the mid-1940s, coal production from the Rosebud Mine reached production of just more than 4 MST per year. However, by 1957 the mine was closed after a decade-long decrease in coal demand as steam locomotives were gradually replaced by diesel locomotives (Morgan, 1966). Total coal production from 1923 to1968 for the Montana PRB was less than 45 MST (Department of Labor and Industry, Safety and Health Bureau, State of Montana, written commun., 2011). Montana Power Company acquired the Rosebud Mine in 1968 and formed a subsidiary, Western Energy Company, to manage and develop the Colstrip properties (U.S. Office of Surface Mining, 1983). Western Energy Company began mining coal at the Rosebud Mine near Colstrip Montana in 1968. One year later, Peabody Coal began operations at the Big Sky Mine just south of Colstrip, but closed operations in 2003 (figs. 2 and 12). The Absaloka Mine, located 10-12 mi west of the Rosebud Mine, began production in 1974 and is owned and operated by Westmoreland Resources, Inc. (figs. 2 and 12). Total production from the Colstrip area is about 708 MST (table 1). The Decker East, West, and North Mines near Decker, Montana (figs. 2 and 12), began operating in 1972 after development of a 19-mi-long railroad spur from Sheridan, Wyoming. Total production from the Decker/Spring Creek area is about 642 MST (table 1). The Spring Creek Mine, also near Decker, Montana, opened in 1979 and is operated by Spring Creek Coal, LLC (figs. 2 and 12). Coal in the Wyoming PRB was first documented in 1859-60 by Ferdinand V. Hayden, a member of Captain W.F. Raynolds' expedition exploring the Lower Yellowstone River. Hayden reported extensive lignite coal between the North Platte River and Pumpkin Butte area northwest of Gillette, Wyoming (Bryans, 1987). Traveling through the Powder River Basin in 1865, James A. Sawyer observed sizeable coal deposits south of Gillette, Wyoming (Gardner and Flores, 1989). In the Wyoming PRB, coal mining began about 1883 near the towns of Glenrock and Douglas, Wyoming (fig. 1); however, it was the development of railroad lines in 1886 and 1887 that greatly affected significant growth in coal mining activity (Gardner, and Flores, 1989). The first underground coal mines in 1888 were the Mine near Douglas, Wyoming, and the Deer Creek Mine near Glenrock, Wyoming (fig. 1), each with production of about 13,000 short tons of coal (Gardner and Flores, 1989). In the Sheridan coal field area (fig. 12), the Buffalo Fuel Company No. 1 underground mine was developed in 1888 (Gardner and Flores, 1989). The nearby Dietz Mine opened about 1890 and by 1925, 17 additional underground mines opened in close proximity to the Dietz Mine (Gardner and Flores, 1989). In 1905, mine production in Sheridan County was about 550,000 short tons of coal annually (Trumbull, 1905). The first surface mine (Peerless) near Gillette, Wyoming opened in 1924, where a 90-ft-thick coal bed was mined (Gardner and Flores, 1989). The Wyodak Coal and Manufacturing Company opened a large surface mine and produced about 33,600 short tons of coal in 1925. By the mid-1900s, advancements in mining equipment and mining techniques made surface mining much more profitable. Most underground mines closed or the companies switched from underground to surface mining methods. Until 1978, most of the coal production in the Sheridan coal field area was from underground mines. Of the Sheridan County cumulative coal tonnage of about 62 MST through 1978, underground mining accounted for about 48 MST
Previous and Current Coal Mining 7 (78 percent). This production came from about 70 underground mines, most of which are about 10 mi north of Sheridan, Wyoming (fig. 12). Surface subsidence pits and troughs mark locations of many of the abandoned underground mine work ings (Glass, 1978). The Dietz 3 and Canyon coal beds in the Sheridan coal field area were surface mined at the Big Horn Mine from 1962 to 2000 (Ellis and others, 1999); more than 47 MST of coal were produced from the mine (fig. 12). Total recorded production from the entire Sheridan coal field area is estimated at about 100 MST of coal (Nick Jones, Wyoming State Geological Survey, written commun., 2009) (table 1). The need for coal increased dramatically in the mid1960s because of the increased demand for electricity from coal-fired power plants. For example, the Dave Johnston Mine in the Glenrock coal field opened in 1958 to supply coal to the adjoining power plant (fig. 12). Production from the Dave Johnston Mine from 1958 to 2000 totaled about 104 MST (Nick Jones, written commun., 2010). The Dave Johnston Mine marked the beginning of large surface mines in the Gillette coal field in the Wyoming PRB. In response to the need for low-sulfur, low-ash coal, production from the Gillette coal field increased: 623,000 short tons in 1972 (Keystone Coal Industry Manual, 1973); 81 MST in 1982 (Keystone Coal Industry Manual, 1983); 151 MST in 1992 (Keystone Coal Industry Manual, 1993); 360 MST in 2002 (Keystone Coal Industry Manual, 2003); and 388 MST in 2012 (Mine Safety and Health Administration, 2012). Although coal production in the Gillette coal field came from 15 surface mines, only 11 are currently active (December 2012): Antelope, Belle Ayr, Black Thunder, Buckskin, Caballo, Cordero Rojo (Cordero Mine), Dry Fork, Eagle Butte, North Antelope/Rochelle, Rawhide, and Wyodak (fig. 12). Coal production is from the Anderson and Canyon coal beds (fig. 13), which when combined in some areas, attains more than 100 ft in thickness. Production in 2012 from the Gillette coal field totaled more than 388 MST (table 1) with almost 52 percent of that total from two mines, the North Antelope Rochelle and the Black Thunder (EIA, 2013). Production from these two mines alone represents about 20 percent of the total U.S. coal production in 2012 (EIA, 2013). Total production (through 2012) from the Gillette coal field is about 8 BST (table 1). Coal Lease Areas In 1983, a report was submitted to the Bureau of Land Management (BLM) for the lease acquisition of Preference Right Lease Applications (PRLA) known as the Stevens North (W-12767, W-14390, W-14392) and the Stevens South (PRLA W-14355) (Western Fuels Association, Inc., 1983). The lease applications are north of the Dave Johnston Mine, in the Dry Cheyenne and Glenrock coal fields in the Wyoming PRB (figs. 2 and 12). These four PRLAs form one unit and are collectively known as the Stevens Project Area. Although no mining has taken place, in-place coal resources were estimated to be 625.3 MST (Western Fuels Association, Inc., 1983). A report detailing the final Environmental Assessment of a lease area known as the Belco-BLM Coal Lease Exchange indicated that the Belco lease area located southeast of Buffalo, Wyoming (figs. 2 and 12) contained between 137 and 185 MST of minable coal at a stripping ratio of 5:1 or less. The minable coal beds in the Belco area are the Healy and the Ucross, in the Wasatch Formation (Bureau of Land Management, 1999). In 2003, Pittsburg and Midway Coal Mining Company proposed a land exchange with the Federal government for lands within the Sheridan coal field in the Wyoming PRB. This land, which encompasses about 2,500 acres in sections 20, 21, 22, 23, 27, 28, 29, 33, and 34, T. 58 N., R. 84 W., is referred to as the PSO lease area (figs. 2 and 12) and is located in the NE ¼ sec. 22, T. 58 N., R. 84 W. (Bureau of Land Management, 2003). Pittsburg and Midway Coal Mining Company estimated that the PSO lease area contains about 112.5 MST of minable Federal coal, of which 107 MST was classified as recoverable. The projected mining rate was estimated at one MST for the first year with subsequent production increasing to 10 MST per year by year five. Within the PSO lease area, the Dietz 1 and Dietz 3 coal beds would be surface mined using a strip ratio of about 2.5:1. The Dietz 1 coal bed is present in the northern one-half of the lease area and is 5-20 ft thick. The Dietz 3 coal bed is present throughout the lease area and averages 41 ft thick. Overburden above the Dietz 1 coal bed is as much as 275 ft thick, whereas overburden above the Dietz 3 where the Dietz 1 is not present, is 20-120 ft thick. The interburden thickness between the Dietz 1 and Dietz 3 beds is 20-140 ft, with a thickening trend from east to west. Two northeast-trending faults approximate the northwest and south east boundaries of the lease area. Although these faults are known to be present, their exact locations and displacements have not been accurately defined by drilling. The displace ments across each of these two major faults are estimated to be 60-180 ft. Generally, the stratigraphic dip is to the northeast at approximately four degrees. There are local areas where the shallow strata dip at higher angles, generally because of local folding or faulting (Bureau of Land Management, 2003). Pittsburg and Midway Coal Mining Company entered into a joint venture agreement with CONSOL Energy Inc. to develop the PSO lease area (Lynn Manning, CONSOL Energy, oral commun., 2009). CONSOL of Wyoming LLC, and Chevron NPRB, LLC, formed a new company, Youngs Creek Mining Company, LLC, to develop and operate the proposed mine (Lynn Manning, CONSOL Energy, oral commun., 2009). The PSO lease area contains coal reserves totaling approximately 315 MST with an estimated heat content of 9,350 Btu/lb and an average sulfur content of 0.47 percent. In July 2012, the PSO lease area was sold to Cloud Peak Energy (Bob Green, Cloud Peak Energy, oral commun., September 2012). In 2010, Arch Coal Inc. acquired the right to mine 572 MST of Montana State-owned coal in Otter Creek, south of Ashland, Montana (figs. 1 and 12); Arch Coal Inc. already controlled 731 MST of privately owned coal in the Otter Creek area (Dennison, 2010). The life-of-mine area includes areas known as Tracts I, II, and III. The proposed
8 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana mine area (Tract II) is owned by Otter Creek Coal, LLC and encompasses approximately 7,640 acres, of which about 4,100 acres would be disturbed under the proposed mine plan; tracts I and III total about 10,580 acres. The proposed project, Tract II, would have production of about 20 MST/yr for a 20-year period (Montana Department of Environmental Quality, 2013). Mining has not commenced at the Otter Creek lease area as of October 2014. Previous Coal Resource Estimates Estimates on coal resources and reserves in the Powder River Basin have been published since 1927 (Dobbins and others, 1927). These estimates were based on different coal beds, coal zones, reliability categories, and geographic boundaries. Differences in minimum coal thickness, maximum overburden depth, and minimum areal extent of coal beds have been used for calculations of coal tonnages. Nevertheless, these studies form the foundation for most of the coal resource compilations that followed. Detailed lists of references can be found in U.S. Geological Survey reports on the four assess ment areas (Luppens and others, 2008; Scott and others, 2010; Osmonson and others, 2011; and Haacke and others, 2013). The following list contains some of the more significant esti mates for coal resources and reserves in different portions of the PRB as well as the entire PRB. The earliest published estimate of coal resources in the PRB was by Dobbin and others (1927) for the Gillette coal field (fig. 6). Their estimate, based on an area of about 3,000 mi2, was about 14.4 BST; however, they were limited to outcrop measurements for their calculation because little subsurface data were available. Combo and others (1949) published a detailed report sum marizing Montana coal resources by county, rank, reliability category, and thickness. Their estimate for coal resources in the Montana PRB was 126 BST. This included reliability categories of measured resources, indicated resources, inferred resources, and hypothetical resources based on distance from drill holes or outcrop and depths up to 2,000 ft. The measured and indicated coal reserves for the Montana PRB were esti mated to be 47 BST for coal beds greater than 2.5 ft thick. Berryhill and others (1950) provided a calculation of total original reserves of subbituminous coal in Wyoming by town ship, overburden thickness, and coal bed thickness. Coal ton nage estimates given for 86 townships entirely or partly within the Gillette coal field totaled about 45 BST (fig. 6). Their estimate was made for all coal beds more than 2.5 ft thick and overburden less than 2,000 ft thick. Those estimates were the sum of measured, indicated, and inferred reserve tonnages. Mapel (1954) estimated 3 BST of coal reserves in the Buffalo-Lake DeSmet area in the Wyoming PRB, in beds more than 2.5 ft thick and under less than 1,000 ft of overburden (fig. 6). Several years later, Mapel (1959) esti mated total coal reserves in the Buffalo-Lake DeSmet area in beds more than 2.5 ft thick and under less than 1,000 ft of overburden at about 6.4 BST. Mapel (1958) estimated about 193 BST of coal was present in coal beds greater than 2.5 ft thick in the entire PRB. The estimate was based on 87 BST in the Montana PRB and 106 BST in the Wyoming PRB. Ayers (1986a) provided an estimate of 1.06 TST of coal greater than 2 ft thick to a depth of 3,000 ft within the Tongue River Member of the Fort Union Formation in the Wyoming PRB (fig. 4). Glass (2001) published an estimate of 1.03 TST of coal for the Wyoming PRB, which included coal beds of any thickness and to all depths, even greater than 6,000 ft. The remaining strippable coal reserve base for the Wyodak coal bed was reported to be 17.9 BST, using a 200-ft cutoff depth for overburden. Ellis and others (2002) estimated 136.1 BST of origi nal coal resource for five coal beds in the Gillette coal field (fig. 6). These resources were calculated for an area of the Gillette coal field encompassing about 1,500 mi2. The esti mates showed that the available coal resource already defined represents about 89 percent of the original coal resource. As documented in these various estimates, coal resource and reserve estimates change as more data become available. Therefore, new estimates provided in this report prove the usefulness of periodically recalculating coal resources and reserves. Estimates of coal resources and coal reserves in this report are a significant refinement of previous coal resource and reserve studies in the PRB. Previous Coal Bed Nomenclature Various names for individual coal beds and coal zones in the PRB have been used since the early 1980s (fig. 13). In fact, as many as 60 different bed names have been used throughout the basin. Historically, coal beds in Wyoming and Montana were named on the basis of a geographic location or the per son who identified or described the bed. A report by Kent and others (1980) described the northern part of the Gillette coal field and established a coal bed nomenclature system that has become the standard for much of the PRB in Wyoming (fig. 13). In that report, Kent used the name "Wyodak" from Mapel (1973) to describe a thick sequence of coals in the PRB. Pierce and others (1990) followed most of the same coal bed nomenclature of Kent and others (1980); however, they mapped the Wyodak coal bed splitting it into the Upper and Lower Wyodak beds and used the Roland bed name in place of the Smith bed (fig. 13). Although Flores and others (1999) followed the Pierce and others (1990) nomenclature, they introduced the concept of the Wyodak-Anderson coal zone, which includes the Smith, Badger, School, Sussex, Big George, Wyodak, Anderson, Dietz, Canyon, and Werner coal beds (fig. 13). A more detailed review of the historical coal geology and stratigraphy is pro vided in Flores and others (2010).
Methodology 9 Methodology A three-phase methodology for calculating coal resources and reserves in the PRB is outlined on the flow chart in figure 14. This methodology has been used consistently for the previ ous four PRB assessments: (1) Gillette coal field by Luppens and others (2008), (2) Northern Wyoming Powder River Basin assessment area (NWPRB) by Scott and others (2010), (3) Southwestern Powder River assessment area (SWPRB) by Osmonson and others (2011), and the (4) Montana Powder River Basin assessment area (MTPRB) by Haacke and others (2013). The first phase involved data collection and editing. The second phase consisted of modeling, including final coal bed correla tions and creation of an inventory of land-use and technical restrictions. The data entry and coal bed correlations tasks col lectively represented the most man-hour-intensive effort of this assessment, representing about eight man-years. The third and final phase involved coal resource and reserve analysis. Phase One (Data Collection and Editing) Data pertaining to coal bed geology, extent and thick ness of coal beds, interburden thickness, parting thickness, overburden thickness, structure, factors affecting coal extrac tion, coal ownership, coal quality, coal sales price, and tax information were gathered during the initial phase of the assessment (fig. 14). The following summaries provide more detail on the collection and editing processes. Data Collection The tremendous growth of CBM development since the early 1990s has facilitated a unique perspective of the subsur face coal stratigraphy in the PRB. The potential to more accu rately delimit and correlate individual coal beds has been greatly enhanced with the completion of more than 27,000 CBM wells with corresponding geophysical logs. The Wyoming Oil and Gas Conservation Commission (WOGCC) Web site con tains digital images of the geophysical logs of wells drilled in Wyoming (Wyoming Oil and Gas Conservation Commission, 2011). Initially, images for 694 logs were downloaded from that Web site to develop preliminary coal bed correlations throughout the Gillette coal field. These images were then used to construct both north-south and east-west hard copy geophysi cal log framework cross sections on approximately six-mile spacing. During the correlation of the framework cross sections, it was realized that the amount of data from these cross sections was insufficient to resolve the complex coal bed stratigraphy. More closely spaced data would be needed, which resulted in an intensive data entry program (Luppens and others, 2008). A preliminary map of the overburden depth to the top of the Anderson coal bed was generated. Based on this overbur den map, additional in-fill drill-hole logs were then selected for data entry at a spacing of about 0.25 mi for areas less than 500 ft of overburden, 0.5 mi for areas of 500-1,000 ft of overburden, and 1 mi for areas of greater than 1,000 ft of overburden. Additional data were added in areas of particularly complex correlations. A 3-mile-wide buffer zone surrounding the Gillette coal field was added to extend the stratigraphic correlations and minimize edge effects when modeling the coal beds. A data collection process similar to this was used for sub sequent PRB assessment areas, where thick coal beds incurred closely spaced CBM development. Well logs for oil and gas and CBM wells were obtained from the WOGCC and MJ Systems (2009, 5085 Oakland St., Denver, CO 80239). USGS personnel completed data entry for 6,387 wells of the total 10,210 data points for the Gillette coal field assessment. Subsequently, USGS personnel entered data for 2,821 points for the NWPRB assessment area, 3,161 points for the SWPRB assessment area, 1,956 points for the MTPRB assessment area, and 276 points for the East Gillette coal field extension area, bringing the total number of data entry points to 14,601. Data from an additional 15,327 drill holes were sup plied by the Montana Bureau of Mines and Geology (MBMG) (accessed 2012 at http://www.mbmg.mtech.edu/gis/ gis-datalinks.asp), Wyoming State Geological Survey (WSGS), and the USGS National Coal Resources Database System (NCRDS). All of the drill-hole data were entered or imported into the StratiFact database program (GRG Corporation, 1998). A total of 29,928 drill holes (of which 21,393 holes were nonproprietary) were used in the PRB assessment (fig. 15). The database for the 21,393 nonproprietary drill holes was published by the USGS in 2013 (Haacke and Scott, 2013). Gamma-ray geophysical logs were available for most of the wells and were the basis for most of the lithologic interpre tation. Normally, oil and gas wells are logged in detail primar ily for deeper target formations. The upper intervals were either not logged or only gamma-logged through the surface casing. Geophysical log data in older oil and gas wells usually con sisted of a combination of spontaneous potential, resistivity, or conductivity logs. The most reliable log suite for coal interpre tation consisted of natural gamma, gamma-gamma density, and resistivity traces; however, many coalbed methane wells were logged with gamma-ray only, either in open hole or through steel drill pipe or casing. Additionally, some of the coalbed methane wells were logged only to the top of the target coal bed which required consulting production records for the coal bed thicknesses. Noncoal lithology was not essential for the coal resource assessment of the PRB; consequently, much of the noncoal lithology was coded generically as rock. It is estimated that the interpretation of all the noncoal intervals would have doubled or tripled the time needed to complete the total data entry effort. Parting intercepts within coal beds and interburden between coal beds were also coded as rock. Intervals that were not logged by geophysical methods, such as the shallow portion of an oil well or CBM well, were designated as "No Log." However, if the thickness of the methane-producing interval was available from production records for those CBM wells not completely logged, that interval was entered as "coal, CBM perf."
10 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Data on various restrictions to mining were gathered and incorporated into GIS. Additionally, information required for the mining and economic evaluation, such as tax information, lease royalty costs, and updated costs for equipment, supplies, and manpower wage scales were assembled. Site visits to operating mines in the PRB were conducted during this initial phase and were an important activity to help ensure that the mine models developed for the coal recoverability analyses reflected current mining practices and approaches. Phase Two (Modeling) Phase two involved the correlation of individual coal beds, creating integrated, multi-coal-bed models, creating land-use and technical restrictions to mining (fig. 14). The coal bed cor relation process is included in the modeling section because the bed nomenclature had to consider some limitations of coal bed modeling to avoid making the models too complex. Coal Bed Correlations Coal bed stratigraphy in the PRB is often complicated because of complex channel systems that controlled coal deposition. Thus, the geology alone makes the task of corre lating individual coal beds in the PRB a significant challenge. In cases where thick partings split coal beds into distinct beds, the coal bed is correlated as a "lower" or "upper" bed of the primary bed. Further complicating the correlation effort was the fact that coal beds extending from Wyoming into Montana often had different names. Also, thick, shallow coal beds in the eastern Gillette coal field and the western PRB, coupled with a lack of substantial subsurface data early in the reporting of the basin, led to a proliferation of local coal bed nomenclature. Flores and others (2010) believed that there is confusion, basinwide, over the names, correlation, and distribution of individual coal beds that requires resolution in order to make meaningful estimates of both coal and CBM resources in the PRB. Because of the existing uncertainties in the correla tion of individual thick coal beds, Flores and others (1999) suggested that coal resource estimates should be performed according to coal-zone intervals. However, meaningful coal resources, and especially reserve assessments, must be founded on geological models of individual coal beds, not by coal zones. Flores and others (2010) attempted to resolve some of the correlation confusion by publishing a database containing 1,715 well logs, with a network of 17 cross sec tions. The primary objectives of the Flores and others (2010) report were to revise and improve the mapping of coal beds in the Fort Union and Wasatch Formations. There were, however, numerous coal bed nomenclature conflicts with tie wells in the database between the north-south and east-west cross sections. The use of multiple bed names for identi cal coal bed intervals in the Flores and others (2010) report database precluded accomplishing the study's objectives. Consequently, the only coal bed maps in the Flores and others (2010) report were based solely on the net thickness of coal beds within the Wyodak-Anderson coal zone, rather than individual coal bed isopach maps. The Gillette coal field report (Luppens and others, 2008) was the first assessment to take advantage of recent CBM drilling, which provided sufficient data control to correlate and map individual beds on a regional scale (fig. 2). Exten sion of the coal bed correlations northward from the Gillette coal field to the Montana State line and westward across the Wyoming PRB to the Sheridan coal field was accomplished in the NWPRB assessment area report (Scott and others, 2010). Completion of the correlation and mapping of the coal beds in the remaining Wyoming portion of the basin was accomplished in the SWPRB assessment area (Osmonson and others, 2011) (fig. 2). The MTPRB assessment area (Haacke and others, 2013) report was the completion of the correlation and mapping of coal beds in the Montana PRB (fig. 2). The initial correlation and coal bed nomenclature stratigraphically below the Wyodak-Anderson coal zone were guided by five USGS cross sections: (1) McLellan and others (1990); (2) Pierce and others (1990); (3) Hardie (1991); (4) Molnia and Pierce (1992); and (5) McLellan (1991). Following data entry by USGS personnel for the Gillette coal field assessment, final correlations were refined from the preliminary framework cross sections. A graphical interface to the StratiFact (GRG Corporation, 1998) database was a critical tool for manag ing the interpretation of large amounts of new stratigraphic data. Using StratiFact, cross sections were selected, edited, and correlations were completed onscreen. Both linear and circular cross sections were constructed to correlate coal beds across the PRB. Circular cross sections that verified clo sure were especially valuable when coal beds either split or thinned adjacent to channels systems. With this process, the beginning and ending drill holes of the cross section are the same, assuring that the coal beds align stratigraphically with each other and provide closure to the section. Figures 16 and 17 show that with new data and circu lar cross sections, previous correlations can be verified or refined. As seen in figure 16, there is a 9-mi gap between drill holes API 49-005-24358 and API 49-005-33013. Both drill holes contain thick coal beds that were assumed to be the Upper Wyodak coal bed (Anderson coal bed in this assess ment) (Molnia and Pierce, 1992). In the Gillette coal field assessment, nine additional drill holes were added between those two drill holes, demonstrating that the new data were essential in revising and improving the confidence in the correlations (fig. 17). Figure 17 shows that the Anderson and Canyon (Lower Wyodak) coal beds do not split and that the thick upper coal bed in API 49-005-24358 is actually the Smith coal bed, not the Anderson (Upper Wyodak) as shown in figure 16.
Methodology 11 The Anderson and Canyon coal beds split and thin as they extend towards the NWPRB assessment area from the northern part of the Gillette coal field (fig. 10) (Scott and others, 2013). Channel areas where coal beds are thin or absent (referred to as "want areas" by Flores and others, 2010) posed challenges for extending coal bed correlations west and north from the Gillette coal field. Figure 18 illustrates a significant "want area" in eastern Sheridan County, Wyoming. Not only were many of the coal beds thin or absent, but drill ing data were relatively sparse because of a lack of sufficiently thick CBM development targets (fig. 15). To correlate around these "want areas," the coal bed correlation process proceeded north through the east margin of the NWPRB assessment area and then westward through the southernmost townships in Montana. The coal beds remained relatively thick enough to extend correlations across the NWPRB assessment area (fig. 18) (Scott and Luppens, 2013). Although correlations focused on the Wyodak-Anderson coal zone in the Gillette coal field, coal beds from the Felix to the Pawnee were correlated (fig. 13). Three relatively persis tent deeper coal beds below the Pawnee bed were informally correlated to the Deep 1, 2, and 3, rather than trying to sort out the various local bed names. Figure 13 shows coal bed nomen clature used for the Gillette coal field, NWPRB assessment area, SWPRB assessment area, and MTPRB assessment area, and this report, as well as their relations to the coal bed names used in previous studies. For the NWPRB assessment area, the Odell and Roberts coal beds, stratigraphically below the Pawnee coal bed, had significant areas 10-ft thick or greater in thickness and were therefore correlated and assessed. The Deep 1, 2, and 3 coal beds were also correlated, but these beds remained rela tively thin and insignificant from a resource standpoint. In the SWPRB assessment area, the Deep 1, 2, and 3 coal beds had significant areas greater than 10 ft in thickness. For the MTPRB assessment report, local names were used for coal beds stratigraphically lower than the Pawnee bed such as the Knobloch (fig. 13). A "dash" was used for formal hyphenated names such as the Flowers-Goodale. Beds with equivalent local names were separated with a virgule (/) for example, the Rosebud/Knobloch bed. The final task of the correlation process was to unify the coal bed nomenclature of the four assessment areas into a single database to support coal bed mapping on a basinwide scale. The first step in this process was to complete the cor relations for deeper coal beds below the Pawnee bed which were not originally assessed in the Gillette coal field report (Luppens and others, 2008). The eastern limit of the Gillette coal field assessment was the subcrop of the thick Anderson and Canyon beds; therefore, the area east of the depth where the deeper coals would crop out was not evaluated. To complete the evaluation of these deeper coal beds, the East Gillette coal field extension was assessed (fig. 2). Setting the east boundary of the extension area at the limit of Tertiaryage rocks in the basin also coincided with the NWPRB and SWPRB assessment area eastern boundaries (fig. 2). The East Gillette coal field extension assessment required supplement ing limited drilling information from the original Gillette coal field database with data entry of additional oil and gas wells. With these additional data, the correlation of the deeper coal beds from the Gillette coal field was expanded towards the east margin of the basin (fig. 8). The last step in developing a unified, correlated database for the PRB was melding the Wyoming and Montana coal bed correlations into a single nomenclature. Since the Wasatch Formation is essentially confined to the Wyoming PRB, there are no significant State-to-State nomenclature issues. The prin cipal coal beds within the Wyodak-Anderson coal zones were also straightforward as bed names such as the Smith, Anderson, and Canyon are used in both Wyoming and Montana. The coal bed nomenclature below the Wyodak-Anderson coal zone is especially problematic. Using StratiFact to display onscreen cross sections effectively resolved equivalent coal beds. Dual bed names separated by a virgule (/) were adopted where it made sense to keep ties to the regional nomenclature. For example, the Deep 3 bed in Wyoming correlated with the Flowers-Goodale bed in Montana. The final name used for this coal bed was the Flowers-Goodale. Figure 13 summarizes how the coal bed names evolved through the four assessment areas and the resultant coal bed nomenclature used for this summary report. As a result of the correlations and unification of coal bed nomenclature, many coal bed names used in other reports were not used in this report. Names eliminated include: Badger, Broadus, Carney, Carlson, Carson, Elk, Kendrick, Kennedy, King, Mackin-Walker, Poker-Jim, Sawyer, Swartz, and Waddle. Coalbed Modeling The next step of Phase two of the assessment (fig. 14) was the creation of digital coal bed models to determine the original resources for all 47 beds. Preliminary coal isopach maps were created using the single-bed modeling program Surfer (Golden Software, 2002) to review coal bed areal extent. The basic assumption used to qualify coal beds for potential coal resource evaluation was a thickness of at least 2.5 ft (Wood and others, 1983). The integrated multibed modeling program PC/Cores (Mentor Consultants, 2005) was used to produce gridded coal bed models for the 47 coal beds identified in the PRB assess ment (fig. 13). This modeling program is designed for coal and mineral assessments and is especially effective for coal bed modeling because of the capability to simultaneously grid multiple beds. The program provides a considerable reduction in total modeling time compared to other programs that grid only one parameter at a time. Grids must be made for coal thickness, parting thickness, coal height (coal plus parting), roof and floor structures, and overburden and interburden
12 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana thicknesses for each bed. The roof grid for each coal bed must be individually subtracted from the surface grid or the floor grid for the next stratigraphically higher coal bed. Most multiple coal bed modeling programs are highly automated with a sophisticated subroutine that uses individual coal bed structure grids to check for drill holes too shallow to penetrate a given bed. This feature produces more accurate digital models without the need for extensive manual editing. The PC/Cores® program code was further modified to allow correlations to pass through the sections of the drill holes that were not logged to reduce the generation of "false zero" thickness values. Quality control methods to verify coal bed correlations and coal bed areal distributions were essential to this assess ment. This was accomplished by generating preliminary isopach and structure contour maps for each modeled bed to check for "bull's eye" anomalies. Also, a routine within the PC/Cores modeling program was used to identify anomalous locations by comparing collar elevations to the digital eleva tion model (DEM) of the Earth's surface; many location errors were resolved using this technique. Methods to reduce the effects of projected contours were also devised to limit erroneous data projections. A circle with a 0.75-mi radius was generated around every data location with at least one coal bed intercept. A line was then digitized through the updip sides of the circles using the locations clos est to the basin margins. This digitized line was used as a grid ding boundary to prevent gridding projections where coal data were insufficient. The boundary line was especially important on the west margin of the basin where the strata are steeply dipping and coal beds are thinning or pinching out (figs. 3, 8, and 9). To generate isopach grids for coal bed geometries, the use of an option in the PC/Cores modeling program known as "pinching" was used. While extracting X, Y, and Z coal bed thickness files to be gridded, the pinching option caused a negative thickness to be generated for a hole where the bed was missing. This resulted in the zero thickness value placed halfway between the nearest positive thickness data point and the actual zero value location. Therefore, use of the pinching function provided a slightly more conservative projection of coal bed areal extent, particularly where data points were more widely spaced. For the final coal bed model, 5 grids including thickness, roof, floor, bed height, and parting, were generated for each coal bed for a total of 235 grids for the 47 coal beds modeled. The coal bed models were gridded at a resolution of 150 meters (m) (about 500 ft) with a total of about 3,954,000 cells in a single grid. The file size of individual grids ranged from about 25 to 45 megabytes. The grids for the coal resource model (coal thick ness, parting thickness, roof elevation, floor elevation, and bed height) for each of the 47 coal beds were converted in PC/Cores to a generic ASCII grid format. These ASCII grids were then exported to ArcView (Environmental Systems Research International, 2006) to perform the last step in Phase two of the assessment, modeling restrictions to mining. Restrictions to Mine Models The final step in Phase two of the assessment was to create grids of land-use and technical restrictions to mining by coal bed. The objective of this step in resource planning is to determine the amount of available coal resources. This pro cess is accomplished by first subtracting the amount of mined coal and clinker from the amount of original resources; the result is remaining resources. Subtracting the amount of landuse restrictions and technical restrictions from the amount of remaining resources yields available resources. The follow ing discussion details the methodology used in determining available resources. The coal bed model files created in PC/Cores were imported into GIS. The GIS was used to allocate coal resources, by first subtracting amounts of various restrictions to mining (fig. 19) (for example, mined coal, towns, National forests, alluvial valley floors) in order to calculate the amount of available coal. ArcView and the ArcView Spatial Analyst extensions (Environmental Systems Research Institute, Inc., 2006) were used to perform the various GIS analyses and ultimately calculate the amount of coal resources. In addition, ArcGIS (Environmental Systems Research Institute, Inc., 2006) was used to project digital coverages, shapefiles, and grids to the assessment area's base map projection. The geographic referencing base for the digital data used for the GIS analysis was the Universal Transverse Mercator (UTM) map projection, using the following parameters: map units meters; zone 13; datum NAD27; and spheroid Clarke, 1866. For this GIS assessment, a grid cell size of 30 m (about 100 ft) was chosen. This smaller grid size was required to better define restrictions to mining. All grids used for the GIS analysis were either originally created with a grid cell size of 30 m or resampled to 30 m from another cell size. In the case of the digital coal model grids, the cell size was resampled from 150 m to 30 m. The first task in the GIS process involved the creation of ArcView (Environmental Systems Research Institute, Inc., 2006) grids from ASCII data representing files for coal, parting, and overburden isopach grids that were created from the digital coal models. These ArcView grids were then used to create a total thickness (coal plus parting) grid, and the areal extent grid for each coal bed to be evaluated. Grids were then created to categorize an extent of a specific theme for the entire PRB. These grid themes consisted of mined-out areas, burned coal areas, land-use restrictions, technical restrictions, overburdento-coal-bed ratios, counties, mineral ownership, stripping ratios, resource reliability categories, and coal bed depth.
Methodology 13 The grid theme for burned coal areas was developed from digital surface clinker information obtained from the Montana Bureau of Mines and Geology Geographic Information Systems Lab (2012) and Coates and Heffern (1999) (fig. 7). To estimate the amount of coal within the PRB that has been burned, it was assumed that there is up to a 3:1 ratio of clinker thickness to burned coal thickness (Coates and Heffern, 1999). Consequently, to estimate the areas of coal within each bed that has been burned, a combination of surface clinker extent, coal overburden thickness, and coal bed thickness was used during the assessment. Specifically, wherever surface clinker is present over a coal bed and the thickness of the overburden is three times (or less) the thickness of the coal, the coal within the bed was considered to be completely burned. This calcula tion produces a conservative estimate of the amount of burned coal throughout the PRB. The grid theme for mineral ownership was obtained from the USGS (2012, available at http://pubs.er.usgs.gov/ publication/ofr981) (fig. 20). The grid themes for mined coal, land-use restrictions, and counties, were derived from digital information obtained from the Natural Resource Information System GIS Data List of the Montana Bureau of Mines and Geology Geographic Information Systems Lab (2011) and the Wyoming Spatial Data Clearinghouse (2009) (fig. 19). The remaining grid themes were developed internally within the USGS using ArcView (Environmental Systems Research International, 2006). The grid of land-use restrictions includes various buffer zones that surround each restricted area. The location and width of these buffers are typically mandated by State or Federal regulations. One of the important improvements in this USGS assessment methodology was revising a technique for defining surface restrictions at depth. Previous economic assessments applied a standard vertical projection downward through the coal beds when applying regulatory surface buffers (such as a 300-ft buffer around an inhabited house) below the surface. Because of the additional setback distance required to main tain a safe mining-pit highwall angle, a restricted area actually widens with depth when surface-mining operations are consid ered. Figure 21 illustrates the effect of depth on overall land-use restriction size. For example, a circular restriction having a diameter of 600 ft at the surface encompasses an area of about 282,600 square feet (ft2), or approximately 6.5 acres. However, at a depth of 200 ft, this same restriction has a diameter of 858 ft and encompasses an area of about 577,900 ft2, or approximately 13 acres. At a depth of 500 ft, the same restriction has a diam eter of 2,144 ft and encompasses an area of about 3,608,400 ft2, or approximately 83 acres. The grid for mined coal accounts for all prior mining within the PRB including those mines shown in figure 12. The coal mineral ownership grid was divided into Federal, State, and private ownership categories (fig. 20). The resource reli ability grids were divided into measured, indicated, inferred, and hypothetical coal categories (Wood and others, 1983). The overburden grids were reported in 5 depth categories: 0-500 ft; 500-1,000 ft; 1,000-2,000 ft; 2,000-3,000 ft; and greater than 3,000 ft. For this assessment, overburden depth is calculated where the coal bed is 2.5 ft thick or greater. The next step in the methodology was to combine indi vidual grids into one composite theme grid. The composite theme grid was then combined with each respective coal bed areal-extent grid. This was done in order to define the PRB resources on a bed-by-bed basis, using all attributes of the grid. Areas within each coal bed that represented mined coal, land-use, and technical restrictions were removed from consid eration. Supplemental to this report are GIS data created using Esri ArcGIS 9.3.1 (Environmental Systems Research Inter national, 2006) that can be used to show mineral ownership, mined out areas, land-use and technical restrictions for all 47 coal beds in map view, along with other pertinent data layers (Kinney and Scott, 2015). Although coal resources were calculated using a minimum thickness of 2.5 ft, coal beds less than 5.0 ft thick were considered technically restricted, for surface mining operations. Consequently, separate PC/Cores® models were produced for coal beds that excluded areas where the coal resources were less than 5.0 ft thick. Coal resources were allo cated to separate stripping ratios for coal beds included in the economic evaluation. Factors Affecting Extraction of Coal Resources Many factors affect the availability of coal for min ing and a four-step screening process defined in the 43 Code of Federal Regulations (CFR) 3420.1-4 was used to deter mine which areas of Federal coal are acceptable for leas ing (Office of the Federal Register, 2003). The following 20 coal-leasing unsuitability criteria are listed in the Code of Federal Regulations, Title 43 Subpart 3461.5 (43 CFR 3461.5). Unsuitability criteria Alluvial valley floors Bald and golden eagle roost and concentration areas Bald or golden eagle nests Critical habitat for threatened or endangered plants Critical habitat for animal species Dwellings, roads, cemeteries, and public buildings Federal lands containing active falcon cliff nesting site Federal land systems Floodplains Fish and wildlife habitat for resident species Habitat for migratory bird species Historic lands and sites Lands used for scientific study Lands with outstanding scenic quality Municipal watersheds National resource waters Natural areas State listed threatened or endangered species State or Indian tribe proposed criteria Rights-of-way and easements (for example, railroads) Wilderness study areas
14 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana These criteria are used to determine if an area is unsuitable for leasing and surface mining and were originally established by the Surface Mining Control and Reclamation Act (SMCRA) of 1977 (30 U.S.C. 1201et seq.). Although developed for lands owned by the Federal government, many of the unsuitability criteria are also applicable to State owned and privately owned lands (fig. 20). For example, areas containing threatened or endangered plant or animal species are protected from destruc tion wherever they occur. Municipal watersheds are also protected from detrimental actions regardless of land owner ship. Not all criteria in the Unsuitable Criteria list affect mining development within the PRB. Other potential land-use restric tions to mining include airports, archaeological areas, coalbed methane wells, oil and gas wells, pipelines, power lines, rivers, lakes, streams, and towns. Restrictions to mining vary with location and local land management regulations. This report follows practices govern ing restrictions to mining in the PRB. In addition, BLM person nel in Casper, Wyoming, and Billings, Montana, provided guid ance concerning restrictions to mining and the distances to be buffered around specific features. Required buffer distances can change through time; however, buffer distances for this assess ment were selected based on current regulations (October 2014). A more detailed determination of restrictions and other avail ability considerations would be necessary as part of the leasing and mine-planning phases for any mining operation. Figure 19 shows areas of land-use restrictions within the PRB; a discus sion of identified mining restrictions follows. Airports The Broadus airport is located near the town of Broadus, Montana, about 2.5 mi northwest of the central business district (fig. 19). For this assessment, the airport (including a 300-ft buffer surrounding the airport) is considered a restriction to mining. The Colstrip airport is located about 4 mi southwest of the central business district of Colstrip, Montana, and is located on reclamation land that is surrounded by adjacent mining areas of the Rosebud Mine. Therefore, the Colstrip airport is not considered to represent a separate restriction to mining for this assessment. The Sheridan County airport is adjacent to the city of Sheridan, Wyoming, and is included within the town of Sheridan restriction buffer area (fig. 19). The Johnson County airport is adjacent to the city of Buffalo, Wyoming, and is included in the town of Buffalo restriction buffer area (fig. 19). The Campbell County airport is adjacent to the city of Gillette, Wyoming, and is included within the town of Gillette restric tion buffer area (fig. 19). Alluvial Valley Floors Areas identified as alluvial valley floors, where mining would interrupt, discontinue, or preclude farming, are consid ered restrictions to mining, according to the Surface Mining Control and Reclamation Act of 1977 (30 U.S.C. 1201 et seq.) (fig. 19). In addition, areas outside the alluvial valley floors may also be designated unsuitable where mining might damage the quantity or quality of water supplying the alluvial valley floors. This assessment did not include these specific areas in the delineation of restrictions. Archaeological Areas No major archaeological areas that would prevent mining have been identified in the PRB. However, there are several minor archaeological and historic sites within the PRB. A mitigation plan would need to be developed before coal min ing disturbed any of these areas. Therefore, coal within these known sites was not excluded from this resource assessment. Coalbed Methane Disputes over ownership of CBM resources have arisen between coal mining and CBM development companies as to whether the CBM resources belong to the owner of the oil and gas estate or the owner of the coal estate. Determination of the ownership of CBM resources was resolved by the U.S. Supreme Court in 1999, ruling that CBM resources are part of the oil and gas estate (Supreme Court of the United States, Amoco Production Co. v. Southern Ute Tribe (98-830), 526, U.S. 865 (1999). In addition, the court specified the owner of a CBM lease has the right to gain access and to develop its estate, and owners of the land surface should be adequately compensated for damage to their property resulting from CBM extraction. The BLM has established Conflict Administration Zones to guide development of CBM leases in the path of near-term coal mining (Bureau of Land Management, 2013). In these zones, standard guidelines offer a process for settling conflicts and scheduling development of each resource under a Federal mineral estate. The production of CBM produces large volumes of groundwater that is pumped from the coal bed. The groundwater is generally discharged to holding ponds for consumption by livestock, discharged to existing drainage systems, released into the atmosphere through the use of misting towers, or reinjected into another stratigraphic unit. Rice and others (2000) investi gated concerns over potential environmental effects of CBM development including possible contamination of surface water, water quality in holding ponds, formation of saline crust on the ground surfaces, lowering of the water table, and possible groundwater contamination or depletion of existing aquifers. Since the early 1980s, more than 27,000 new CBM wells have been drilled in the Wyoming PRB (Wyoming Oil and Gas Conservation Commission, 2011) (fig. 15). Production of CBM is mostly from the Wyodak-Anderson coal zone (Smith, Anderson, and Canyon coal beds). The area of high CBM potential in Wyoming is controlled by the distribution of thick coal beds (fig. 22). In 2008, about 535 billion cubic ft of CBM was produced from 24 unique coal deposits in 10 Tongue River Member coal zones that occur in the Wyoming PRB (Jones, 2010a). The CBM resource in the Wyoming PRB is estimated to be 37 trillion cubic ft assuming 65 cubic ft of CBM per ton of in-place coal (De Bruin, 2009; Nick Jones, Wyoming Geological Survey, oral commun., 2009). The production life
Methodology 15 of CBM wells is estimated to be about 10-12 years, although production from multiple beds can extend the life of the well by an additional 10-30 years (De Bruin and others, 2004). CBM development in the Montana PRB began in about 1991, but has proceeded at a much slower pace than in the neighboring Wyoming PRB. Approximately 1,100 wells have been drilled near the Decker Mine, along the Montana- Wyoming border (Montana Board of Oil and Gas, accessed June 2011, at http://www.bogc.dnrc.mt.gov). CBM development in the Montana PRB is restricted to a relatively small area in Big Horn County that includes T. 8-9 S., R. 39-41 W. (fig. 15). Although current (October 2014) CBM production is from the Smith, Anderson, Dietz 2, Dietz 3, Canyon, Werner/ Cook, and Gates/Wall coal beds, there may be additional potential for production from deeper coal beds in the Montana PRB. Van Voast and Thale (2001) identified areas of high, moderate, and low CBM potential for the MTPRB (fig. 22). The lack of CBM expansion in the Montana PRB is because of a combination of less favorable coal bed targets and increased distance from existing infrastructure. Coal beds in the Montana PRB are not as well suited to CBM develop ment as coal beds in the Wyoming PRB because they lack the overall depth and thickness when compared to the central and southern PRB coal beds. Coal beds become shallower and eventually crop out to the northern portion of the MTPRB in response to structural and topographic control. Although this may be advantageous for surface mining, it is not beneficial for CBM development. Coal beds at shallow depths or near outcrop are likely to have lower hydrodynamic pressures (the pressures necessary to retain the adsorbed methane). Under reduced pressures, methane gas in coal beds can migrate towards the outcrop and eventually escape. Although there are thousands of CBM wells within the PRB, designating all of these wells and their accompanying pipeline infrastructure as being restrictive to mining would exclude a significant volume of coal resource from min ing consideration. For the purpose of this assessment, it is assumed that coal within any part of the PRB will be mined after CBM operations have ceased in that area; therefore, the wells and accompanying pipeline infrastructure are not consid ered a restriction to mining. Dwellings and Buildings Individual dwellings and buildings that exist outside of incorporated areas (such as Colstrip, Montana) are not consid ered restrictions to mining within the PRB. These structures are typically purchased by a coal company, which could move or raze them in order to proceed with mining. Federal Land Systems Almost 86 percent of the coal in the PRB is owned by the Federal government and must be leased in order to be mined. The largest contiguous parcel of Federal-owned land in the PRB is the Custer National Forest, in the Montana PRB (fig. 19). The Custer National Forest covers an area of about 783 mi2 in western Powder River County and extends into southern Rosebud County. The same unsuitability criteria and land-use conflicts discussed earlier in this report apply to coal mining in the Custer National Forest. Therefore, the national forest is a restriction to surface coal mining, and the restric tion includes a buffer that extends 300 ft beyond the forest's boundary. However, the BLM could develop coal leasing and mining stipulations in cooperation with the U.S. Forest Service (USFS) for underground coal mining. Federal subsurface coal ownership is shown in figure 20. Fort Keogh National Wildlife Refuge is located imme diately southwest of Miles City, Montana, at the northern boundary of the Montana PRB (fig. 19). A national refuge is typically a restriction to mining. Because the mapped coal beds do not extend into the refuge, the Fort Keogh refuge did not restrict any assessed resources. The southern part of the Gillette coal field is part of the Thunder Basin National Grassland that includes scattered Federal lands under the jurisdiction of the USFS. The same unsuitability criteria and land-use conflicts discussed in this report apply to coal mining on the Thunder Basin National Grassland. Where the mineral ownership is Federal, the BLM develops coal leasing and mining stipulations in coopera tion with the USFS. Therefore, the Thunder Basin National Grassland is not considered a restriction to mining. Historic Lands and Sites The site of the "Battle of Wolf Mountains" is about 3 mi southwest of Birney, Montana, along the valley of the Tongue River (figs. 1 and 19). This site is the location of the last major battle of the Great Sioux War of 1876-1877 (National Park Service, 2012) and was added to the National Register of Historic Places in 2001. In 2008, the site became a National Historic Landmark; therefore, the 1,300-acre site is a restric tion to mining. Oil and Gas Development The Hilight gas plant is approximately 7 mi northeast of the town of Wright, Wyoming, and connects to several major pipelines for gas and crude oil, as well as a pipeline for gas processing products (fig. 19). This installation, with a 100-ft buffer is considered a restriction to mining. The Kitty gas plant also connects to several major pipelines for gas and crude oil, and gas processing products. However, the plant is within the jurisdiction of the buffer zone restriction surrounding the town of Gillette, Wyoming. Current infrastructure for production and transport of oil and gas in the area includes roads, pipelines, compressor sta tions, and separators. Generally, there is little conflict between coal development and conventional oil and gas development in the PRB, as oil and gas reservoirs are primarily in stratigraphic units below minable coal beds. Where oil and gas development and coal mining occur in the same areas, mining is confined to areas outside a specified buffer distance from wells, pipelines, and other oil and gas related structures. Resolution of land-use
16 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana conflicts between coal mining and the oil and gas field devel opment will depend on economic conditions, regulations, and negotiations between oil developers and coal developers. Thousands of oil and gas wells are located throughout the PRB. An area around a major cluster of active wells might be eliminated from mining activities until these wells are no longer actively producing, or mining activities might proceed around individual active wells that are given a buffer zone. Conversely, specific wells might be plugged and then reestab lished after mining. For this assessment, it was assumed that the wells will no longer be actively producing when mining operations affect them; they are not considered to be restric tions to mining. Pipelines There is a network of underground oil and gas pipelines throughout the entire PRB. Most of these pipelines could be moved so that surface mining could proceed. However, mov ing and restoring them would represent an added economic cost to mining. In any case, pipelines were not considered to be restrictions to mining for this assessment. Power Lines All power lines within the PRB could be moved to accommodate surface mining operations and are not consid ered a restriction to mining in the PRB. Railroads There are two main railroad routes through the Gillette coal field in the Wyoming PRB (fig. 19). The generally eastwest route in the north part of the Gillette coal field is a rail line of the Burlington Northern Santa Fe Railway that runs northwesterly through Sheridan, Wyoming. The north-south route in the eastern part of the Gillette coal field is a combi nation of rail lines of both the Burlington Northern Santa Fe Railway and the Union Pacific Railroad. This combination of rail lines is referred to in this report as the "Joint Line" and runs from Gillette, Wyoming, south to Douglas, Wyoming. In addition to the main rail lines, a number of additional spur rail lines serve existing coal mines. However, these spur lines can be moved as the mining operations progress, and they are not considered a restriction to mining. Although it is conceiv able that the main lines of the existing rail routes could also be relocated to allow mining to proceed, it is assumed that these main rail lines would not be moved and are restrictions to min ing. The total restricted width for each main rail line, including the right-of-way and a 100-ft buffer along each side, is 600 ft. The main railroad route through the Montana PRB is an east-west rail section of the Burlington Northern Santa Fe Railway that is in the extreme northern part of the basin. It is not considered a restriction because coal beds do not extend into this area (fig. 19). In addition to the main rail line, there are three spur rail lines that exist over coal resource areas within the Montana PRB. Two of the spur lines connect to this main rail line and extend south to Absaloka and Rosebud Mines. The third spur rail line connects to the main rail line of the Burlington Northern Santa Fe Railway south of the assess ment area (near Sheridan, Wyoming) and extends north to the Decker and Spring Creek Mines. It is assumed that the spur lines would be moved as necessary for mining. They are not considered to be restrictions to mining. Rivers, Lakes, and Streams The most significant rivers in the PRB are the Powder and the Tongue. All of the rivers and tributaries in the PRB are shallow and slow moving. Surface mining operations could temporarily relocate the courses of smaller streams and then return them to their pre-mining locations during mine reclamation. Only the parts of these water courses that have been designated by the State Land Quality Division as alluvial valley floors significant to farming would need to be preserved with no modification. In contrast, the Yellowstone River is a more prominent water course and is considered to be a restriction to mining (fig. 19). However, like the main rail line and Interstate Highway 94, the Yellowstone River lies in the extreme northern part of the PRB beyond the extent of coal beds and subsequently has no restriction effect. The North Platte River flows through a small part of the southern end of the Wyoming PRB (fig. 19). This prominent water course is considered a restriction to mining. In addition to the width of the river, the restriction includes a 100-ft buffer on each side. The most significant body of flowing water in the Gillette coal field is the Belle Fourche River. It is shallow and slow moving; therefore, surface mining operations could relocate the course of this river and return it to the pre-mining location during reclamation. Shallow lakes and small ponds that exist within the PRB could either be temporarily moved during mining or simply reformed after the mining operation ceased. However, the Tongue River Reservoir, a recreational site and water supply source located about 2.5 mi northeast of Decker, Montana, is considered to be a restriction to mining for this assessment (fig. 19). The restriction includes a 100-ft buffer surrounding the reservoir. Lake DeSmet, a recreational site and water sup ply source located about 6 mi north of Buffalo, Wyoming, is considered a restriction to mining and includes a 100-ft buffer surrounding the lake (fig. 19). Roads County roads within the PRB are not considered to be a restriction to mining because they could be relocated or temporarily blocked off to allow mining to proceed. A number of State and U.S. highways including Interstate Highway 94, Interstate Highway 90, and Interstate Highway 25, are present within the area (fig. 19). For this assessment, it is assumed that any State highway could be relocated to allow for mining. The Interstate highways are considered a restriction to mining. The total restricted width is 450 ft, including the highway right-ofway and a 100-ft buffer on each side.
Methodology 17 State Lands and Trusts Two State parks are within the Montana PRB: the Rosebud Battlefield State Park and the Tongue River Reservoir State Park (fig. 19); both parks are considered to be restrictions to mining. The Rosebud Battlefield State Park is about 15 mi northwest of Decker, Montana, and the Tongue River Reservoir State Park is about 6 mi northeast of Decker. The restriction for each park includes a buffer that extends out to a distance of 300 ft beyond the park boundary. Also within the Montana PRB are a fishing access site (Twelve Mile Dam) and two conservation easements (fig. 19). The fishing access site and one of the easements are under the jurisdiction of the Montana Fish, Wildlife & Parks. The other conservation easement is overseen by the Montana Land Reliance. These lands are considered to be restrictions to min ing; however, they have no restriction effect on the coal beds because the coals do not extend into their locations. Towns The municipalities of Colstrip and Broadus are within the PRB and are permanent restrictions to mining (fig. 19). In addition to the actual incorporated area, the mining restric tion for each municipality includes a buffer that extends 300 ft beyond the municipality limits (extraterritorial jurisdiction). The entire municipalities of Buffalo, Clearmont, Gillette, Ranchester, Sheridan, and Wright, and parts of Douglas and Rolling Hills are within the Wyoming PRB (fig. 19). In addi tion to the actual incorporated area for each municipality, the mining restriction includes a buffer that extends beyond the municipality limit. Phase Three (Assessment of Resources and Reserves) The methodology for resource assessment in the geologi cally complex PRB was accomplished in two stages. The PRB was divided into five geographic areas to manage database size and publish more timely results. Four of those areas are in the Wyoming PRB and one is in the Montana PRB: (1) Luppens and others (2008) reported on the first assessment area, summarizing geology, coal resources, and reserves for the Gillette coal field; (2) Scott and others (2010) summarized the second assessment area and presented results on geology, coal resources, and reserves for the Northern Wyoming Powder River Basin assessment area (NWPRB assessment area); (3) Osmonson and others (2011) summarized the third assess ment area and presented results on geology and coal resources in the Southwestern Powder River Basin assessment area (SWPRB assessment area); and (4) Haacke and others (2013) summarized the fourth assessment area and presented results on geology, coal resources, and reserves for the Montana Powder River Basin assessment area (MTPRB assessment area). The fifth area (East Gillette coal field extension) extends east from the Gillette coal field and was evaluated for this report specifically to provide a more comprehensive map ping of coal beds below the Wyodak-Anderson coal zone and to complete the assessment of the entire PRB. The Gillette coal field was assessed first, followed in order by the NWPRB assessment area, the SWPRB assessment area, and the MTPRB assessment area. This report represents the final stage of the PRB assessment, which includes the results of the four regional studies and the east extension of the Gillette coal field. This report provides the first published maps of individual coal beds for the entire PRB. Two factors critical to this accomplishment were: (1) completion of the correlation of coal beds stratigraphi cally lower than the Wyodak-Anderson coal zone, including additional data entry in the east Gillette coal field extension (fig. 2) and (2) resolution of the proliferation of local bed names throughout the entire basin. Figure 13 illustrates the progressive inclusion of deeper coal beds through the four assessment reports. It was anticipated that minor revisions to coal bed correlations and names would be encountered between assessment areas. Correlations within the WyodakAnderson coal zone remained essentially consistent through out each of the three Wyoming assessments; however, there were revisions in names for beds stratigraphically lower, especially from Wyoming into Montana. The discussion of the coal bed correlation process under the Phase two section of the Methodology section of this report addresses the con ventions used to derive a uniform coal bed nomenclature for the entire PRB (fig. 13). The data entry and correlation effort to produce this report represents approximately 14 man-years of work with more than 250,000 digital well logs and multiple onscreen cross sections viewed. The completed database was used to generate the final geologic model which included coal thick ness, roof, and floor grids for each modeled coal bed. The following sections provide a brief description of each assessed coal bed, including a discussion of cross sec tions to illustrate the regional coal geology trends, a summary of coal resource volumes, and perspectives on the deposi tional history provided by the geometry of the individual beds. The economic analyses for each of the assessment areas provides estimates of the volumes of available coal (after all restrictions to mining are subtracted) that are currently classified as reserves or potentially recoverable to a 10:1 stripping ratio. Coal Bed Assessment Coal resources were classified according to geologic assurances (certainty of existence) or reliability, which are directly dependent on the density of geologic data points (fig. 15). The different reliability categories are: (1) mea sured (0.25 mi from point of measurement); (2) indicated (0.250.75 mi from point of measurement); (3) inferred (0.75-3.0 mi from point of measurement); and (4) hypotheti cal (greater than 3.0 mi from point of measurement) (Wood and others, 1983). Supplemental to this report are the GIS
18 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana data created using Esri ArcGIS 9.3.1 (Environmental System Research International, 2000) that can be used to show reli ability categories in map view for all 47 coal beds, along with other pertinent data layers (Kinney and Scott, 2015). Original, remaining, and available resources were cal culated for all 47 coal beds in the PRB and are reported by reliability category (table 4), overburden category (table 5), ownership category (table 6), and assessment area name (table 7). Tables 4-7 also show tonnages for burned coal (clinker), mined coal, land-use restrictions, and technical restrictions for each coal bed. In this report, the areal extent for overburden depth maps match the areal extent of the 1.0 ft (or greater) thickness isopach maps. The greatest depth to the top of the coal for most coal beds is along the axis of the basin. A typical surface mining sequence begins at the ground surface; therefore, the following descriptions of coal beds in the PRB are discussed from young est to oldest. Seven coal beds occur in the Wasatch Formation (Upper Healy, Healy/Lower Ulm, Murray, Ucross, Upper Felix, Felix, Lower Felix); the remaining 40 beds are in the Tongue River Member of the Fort Union Formation (fig. 23). Wasatch Formation Coal Beds The Buffalo-Lake DeSmet area contains Wasatch Formation coal beds that have been previously evaluated for potential mining (fig. 12) (Osmonson and others, 2011). These coal beds are collectively known as the Lake DeSmet coal zone (fig. 13) and are estimated to be 250 ft thick (Mapel, 1959; Obernyer, 1978, 1980). Obernyer (1978, 1980) suggested that the Lake DeSmet coal zone represents the coalescing of several major coal beds, possibly in response to basin-margin faulting in Eocene time. To calculate resources for this assessment area, the Lake DeSmet coal zone was divided into four coal beds (Upper Healy, Healy/Lower Ulm, Murray, and Ucross). Despite the fact, that the Lake DeSmet coal zone is the thickest known coal in the United States (Jones, 2010b), no significant, large-scale mining has occurred in the area. The largest coal resource in the Lake DeSmet coal zone is within the Upper Healy and Healy/Lower Ulm coal beds, which have a composite stripping ratio greater than 5:1, making it unfavorable from a mining standpoint. Land-use restrictions for Buffalo, Lake DeSmet, and Interstate Highway 90, negatively affect the availability of the coal beds for mining (fig. 19). Also, the upper portions of these coal beds have been burned or baked over much of the area (Smith and others, 1972; Glass, 1997). The extent of the resulting clinker can be seen in figure 7. Finally, the coal quality in the Lake DeSmet coal zone is significantly inferior to coal quality currently being produced from the PRB, which would pose a competitive disadvantage for developing these resources (Luppens, 2011; Osmonson and others, 2011). Upper Healy and Healy/Lower Ulm Coal Beds The Upper Healy is the uppermost (youngest) coal bed in the Wasatch Formation and is areally limited to the westcentral part of the Wyoming PRB (fig. 24). This bed is the uppermost bed that composes the Lake DeSmet coal zone of Obernyer (1978, 1980). The Upper Healy, which was identi fied on 186 geophysical well logs, has a maximum thickness of 77 ft and averages 12 ft (fig. 23). Of the 6.9 BST of original resource, about 5.3 BST are considered as available resources (tables 4-7). Depth to the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed to about 1,000 ft along the western extent of the bed. About 98 percent of the available resource is at a depth less than 500 ft (fig. 25, table 5). Of these available resources, about 69 percent of the coal mineral estate is owned by the Federal government (table 6). The Healy/Lower Ulm coal bed identified in this assess ment correlates to the Healy coal bed of Mapel (1959). This bed has approximately the same areal extent as the Upper Healy coal bed and is known as the Healy in the Lake DeSmet area and the Lower Ulm in the central part of the Wyoming PRB (fig. 26). Both areal extents are defined by outcrop and clinker. More than 50 percent of the area of coal bed thickness exceeds 20 ft with one small area of thickness more than 40 ft. The bed, which was identified on 658 geophysical well logs, has a maximum thickness of 83 ft and an average thickness of 14 ft (fig. 23). Of the 13.0 BST of original resource, about 10.7 BST are considered as available resources (tables 4-7). Depth to the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed to about 1,000 ft along the western extent of the bed. About 87 percent of the available resource is at a depth less than 500 ft (fig. 27, table 5). Of these available resources, about 65 percent of the coal mineral estate is owned by the Federal government (table 6). Murray Coal Bed The Murray coal bed was correlated in this report with the Murray coal bed of Mapel (1959) and is present only in the west-central Wyoming PRB (fig. 28). The coal bed has approximately the same areal extent as both the Healy/Lower Ulm and Upper Healy coal beds. Identified on 785 geophysi cal well logs, the Murray has a maximum thickness of 14 ft and an average thickness of 3 ft (fig. 23). Of the 2.7 BST of original resource, about 0.6 BST are considered as available resources (tables 4-7). Depth to the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed, to about 1,000 ft along the western extent of the bed. About 62 percent of the available resource is at a depth less than 500 ft (fig. 29, table 5). Of these available resources, about 63 percent of the coal mineral estate is owned by the Federal government (table 6). Ucross Coal Bed Equivalent to the Ucross coal bed of Mapel (1959), this bed is the lowest coal bed in the Lake DeSmet coal zone and is limited to the west-central Wyoming PRB (figs. 13 and 30). As seen in the isopach maps of the Upper Healy/Lower Ulm, Healy, Murray, and Ucross coal beds, (figs. 24, 26, 28, and 30) the areal extent of all four beds is similar. The Ucross was identified on 591 geophysical well logs, has a maximum thick ness of 40 ft, and an average thickness of 7 ft (fig. 23). Of the
Methodology 19 6.8 BST of original resource, about 4.5 BST are considered as available resources (tables 4-7). Depth to the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed, to about 1,500 ft along the western extent of the bed. About 34 percent of the available resource is at a depth less than 500 ft (fig. 31, table 5). Of those available resources, about 53 percent of the coal mineral estate is owned by the Federal government (table 6). Upper Felix, Felix, and Lower Felix Coal Beds The Upper Felix coal bed is an upper split of the Felix coal bed and is geographically limited to the central Wyoming PRB (fig. 32). This coal bed, which was identified on 1,989 geophysical well logs, has a maximum thickness of 19 ft and an average thickness of 4 ft (fig. 23). Of the 2.1 BST of original resource, about 1.2 BST are considered as available resources (tables 4-7). Depth to the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed, to about 1,000 ft along the western extent of the bed. About 95 percent of the available resource is at a depth less than 500 ft (fig. 33, table 5). Of those available resources, about 94 percent of the coal mineral estate is owned by the Federal government (table 6). The Felix coal bed has a larger areal extent than the Upper Felix and is limited to the central Wyoming PRB (fig. 34). The coal bed, identified in 4,444 geophysical well logs, has an average thickness of 12 ft and a maximum thickness of 55 ft (fig. 23). Of the 18.8 BST of original resource, about 16.8 BST are considered as available resources (tables 4-7). Depth to the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed, to about 1,500 ft where the coal bed is thickest; about 85 percent of the available resource is at a depth less than 500 ft (fig. 35, table 5). Of those avail able resources, about 93 percent of the coal mineral estate is owned by the Federal government (table 6). The Lower Felix is the lowest coal bed identified in the Wasatch Formation and is present in two large areas in the central and northwestern Wyoming PRB (fig. 36). Identified on 4,109 geophysical well logs, this bed has an average thickness of 7 ft and a maximum thickness of 53 ft (fig. 23) along the western margin of the Wyoming PRB. Of the 19.4 BST of origi nal resource, about 14.9 BST are considered available resources (tables 4-7). Depth to the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed, to about 2,000 ft along the axis of the basin; about 23 percent of the available resource is at a depth less than 500 ft (fig. 37, table 5). Of the total available resource, about 69 percent of the coal min eral estate is owned by the Federal government (table 6). Available coal resources in the Wasatch Formation coal beds (Upper Healy, Healy/Lower Ulm, Murray, Ucross, Upper Felix, Felix, and Lower Felix) in the PRB total about 54 BST (tables 4-7). Of the total available coal resource, about 75 percent of the coal mineral estate is owned by the Federal government. Available coal resources less than 500 ft in depth total about 64 percent (tables 4-7). Fort Union Formation Coal Beds Although coal beds can be present in all three members of the Fort Union Formation, minable beds in the PRB are limited to the Tongue River Member (fig. 5). Forty coal beds occur within this formation with some attaining a thickness of over 200 ft (fig. 23). Coal beds exposed at the surface in the PRB are progressively older in the northern part of the basin because of the south-dipping structure of the Montana PRB, combined with a decrease in topography. The Fort Union Formation contains some of the thickest and most extensive deposits of subbituminous coal in the world (Molnia and Pierce, 1992). Most of this coal is in the Wyodak-Anderson coal zone in the Gillette coal field in the Wyoming PRB (Flores and others, 1999). Generally, coal beds below the Wyodak-Anderson coal zone that are present in the Montana PRB tend to be thinner and more discontinuous, with the exception of the Pawnee, Rosebud/Knobloch, and FlowersGoodale beds (fig. 23). Roland (Upper Rider), Roland (Lower Rider), Roland (Baker), and Roland (Taff) Coal Beds The Roland (Upper Rider) coal bed is an upper split of the Roland (Baker, 1929) bed and is present in the central and northern Wyoming PRB, where it reaches a maximum thickness of 32 ft (figs. 23 and 38). The bed, which was identified on 5,710 geophysical well logs, has an average thickness of 4 ft (fig. 23). Although most of this bed is less than 10 ft thick, it is significant because it marks the contact between the Wasatch and Fort Union Formations. Of the 13.5 BST of original resource, about 8.3 BST are consid ered as available resources (tables 4-7). Depth to the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed, to about 2,000 ft along the axis of the basin. Only about 30 percent of the available resource is at a depth less than 500 ft (fig. 39, table 5). Of the total avail able resource, about 90 percent of the coal mineral estate is owned by the Federal government (table 6). Identified on 1,619 geophysical well logs, the Roland (Lower Rider) bed has a maximum thickness of 20 ft and an average thickness of 4 ft (fig. 23). Although less continuous extent than the Roland (Upper Rider), it is present in several small areas in the central and northwestern Wyoming PRB (fig. 40). Of the 3.3 BST of original resource, about 1.7 BST are considered as available resources (tables 4-7). Depth to the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed, to about 2,000 ft along the axis of the basin; only about 7 percent of the available resource is at a depth less than 500 ft (fig. 41, table 5). Of the total avail able resource, about 87 percent of the coal mineral estate is owned by the Federal government (table 6). For this assessment, the Roland of Baker (1929) is referred to as the Roland (Baker) coal bed. The bed was identified in 9,987 drill holes, has a maximum thickness of 40 ft, and averages 10 ft thick (fig. 23). The coal bed is present in a large area in the central and northwest Wyoming PRB
20 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana extending into the Montana PRB near the Decker and Spring Creek Mines (figs. 12 and 42). It crops out to the north and east and thickens to the northwest. The largest coal resource is in the northwestern part of the Wyoming PRB, where it attains a thickness of 40 ft. Of the 47.8 BST of original resource, about 43.3 BST are considered as available resources (tables 4-7). Depth to the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed, to about 2,000 ft south of the Decker and Spring Creek Mines; about 35 percent of the available resource is at a depth less than 500 ft (fig. 43, table 5). Of the total available resource, about 83 percent of the coal mineral estate is owned by the Federal government (table 6). The Roland (Baker) was included for the economic analysis to determine the coal reserve base. The Roland of Taff (1909) is the oldest bed of the Roland coal bed sequence. Hereafter the Roland of Taff (1909) will be referred to as the Roland (Taff) coal bed. The areal extent of the Roland (Taff) is limited to the northwest Wyoming PRB, extending into the southwest Montana PRB (fig. 44). This coal bed was identified in 953 geophysical well logs, has an average thickness of 3 ft and a maximum thickness of 27 ft (fig. 23). One small area along the western extent of the bed contains coal that exceeds a thickness of 20 ft. Of the 3.4 BST of original resource, about 1.3 BST are considered as available resources (tables 4-7). Depth to the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed, to about 1,500 ft over the areas of the thickest areas the coal bed; about 52 percent of the available resource is at a depth less than 500 ft (fig. 45, table 5). Of the total available resource, about 78 percent of the coal mineral estate is owned by the Federal government (table 6). Upper Smith and Smith Coal Beds For this assessment, the Upper Smith, Smith, Anderson Upper Rider, Anderson Lower Rider, Anderson, Lower Anderson, Dietz 1, Dietz 2, Dietz 3, Dietz 4, Upper Canyon, Canyon, Lower Canyon, Upper Ferry, Ferry, and Werner/Cook coal beds constitute the Wyodak-Anderson coal zone (figs. 13 and 23). The Upper Smith is stratigraphically the uppermost bed in the Wyodak-Anderson coal zone. The Upper Smith bed is present in small areas in the southwestern part of the Wyoming PRB and in the southwestern part of the Montana PRB (fig. 46). This coal bed was identified on 326 geophysical well logs, has a maximum thickness of 36 ft, and an average thickness of 3 ft (fig. 23). This coal attains a thickness of about 20 ft in a small area near the abandoned Dave Johnston Mine (fig. 12). Of the 1.0 BST of original resource, about 0.4 BST are considered as available resources (tables 4-7). Depth to the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed, to about 2,500 ft along the axis of the basin; about 46 percent of the available resource is at a depth less than 500 ft (fig. 47, table 5). Of the total available resource, about 81 percent of the coal mineral estate is owned by the Federal government (table 6). The Upper Smith coal bed has approximately the same areal extent as the Roland (Baker) bed (fig. 42) in the western one-half of the Wyoming PRB, extending into the southwestern part of the Montana PRB near the Decker and Spring Creek Mines (figs. 12 and 48). The limits of the bed gradually thin and eventually pinch out. To the northwest, interburden between the Smith and the Anderson becomes very thin; however, the Smith does not merge with the Anderson in any drill holes. The bed thickens dramatically west of Wright, Wyoming, towards the center of the basin where it is locally referred to as the "Big George" coal bed (fig. 8). Jones (2010a) also verified that the Smith and Anderson do not merge by showing an angular relation between the Roland coal beds (Baker and Taff) and the lower Wyodak Rider coal zone (Smith Rider and Smith/Big George coal beds). The largest coal resource in the Smith bed occurs in the central to southern part of the extent of the coal bed, where the bed attains a thickness of over 200 ft (fig. 48). The Smith coal bed, as interpreted from 9,334 drill holes, has a maximum thickness of 278 ft, and averages 24 ft thick (fig. 23). Of the 126.4 BST of original resource, about 122.9 BST are considered as available resources (tables 4-7). Depth to the top of the bed ranges from shallow subcrop along the eastern extent of the bed, to about 2,500 ft along the axis of the basin (fig. 49); only about 4 percent of the available resource is at a depth less than 500 ft making the strip ratio of coal to rock undesirable for surface mining. Therefore, despite the thickness of the Smith coal bed, most of the resource would be considered too deep for surface mining, but is a potential resource for future underground min ing. Of the total available resource, about 88 percent of the coal mineral estate is owned by the Federal government (table 6). The Smith bed was included in the economic analysis to deter mine the coal reserve base. Anderson Upper Rider, Anderson Lower Rider, Anderson, and Lower Anderson Coal Beds The Anderson Upper Rider bed is the uppermost of two splits above the Anderson coal bed and is present only in small, isolated areas in the central part of the Wyoming PRB (figs. 23 and 50). This coal bed was identified in 343 drill holes, has an average thickness of 3 ft, and a maximum thick ness of 18 ft (fig. 23). Of the 0.3 BST of original resource, about 0.04 BST are considered as available resources (tables 4-7). Depth to the top of the coal bed ranges from shallow subcrop along the eastern extent, to about 1,500 ft over the thickest portion of the coal bed; about 59 percent of the available resource is at a depth less than 500 ft (fig. 51, table 5). Of the total available resource, about 71 percent of the coal mineral estate is owned by the Federal government (table 6). The Anderson Upper Rider was included in the eco nomic analysis to determine the coal reserve base. The Anderson Lower Rider bed is the lower of two splits above the Anderson coal bed. This coal bed was identified in 480 drill holes, has a maximum thickness of 20 ft, and
Methodology 21 averages 8 ft thick (fig. 23). The coal bed is only present in one small area in the south-central Wyoming PRB (fig. 52). Of the 0.8 BST of original resource, about 0.5 BST are con sidered as available resources (tables 4-7). Depth to the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed, to about 3,000 ft over the thickest portion of the coal bed; about 96 percent of the available resource is at a depth less than 500 ft (fig. 53, table 5). Of the total available resource, about 94 percent of the coal mineral estate is owned by the Federal government (table 6). The Anderson is the principal minable coal bed in the Wyodak-Anderson coal zone in the Gillette coal field and also a principal CBM production target coal bed in the Wyoming PRB. The bed is present in much of the Wyoming PRB and extends into the Decker and Spring Creek Mine areas in the southwest Montana PRB (figs. 12 and 54). A large area of thin coal separates the bed into two thick pod-like areas in the northwestern part of the Wyoming PRB (about T. 56 N., R. 78 W.) (fig. 54). A channel area in T. 46 N., R. 70 W. bisects the thickest part of the Anderson bed where the bed thins or is absent. The Anderson, Dietz 2, and Dietz 3 coal beds are presently mined at the Decker and Spring Creek Mines in the Montana PRB (fig. 12). The Anderson coal bed was first correlated by Baker (1929) as the Dietz 1 bed. It was also referred to as the Dietz 1 by the Pittsburg and Midway Coal Mining Company in the PSO lease area in the Sheridan coal field (figs. 2 and 12). However, the Anderson and the Dietz 1 are correlated as separate beds for this report. Identified in 11,774 drill holes, the Anderson bed has an average thickness of 24 ft, and a maximum thickness of 225 ft near the Jacobs Ranch Mine (figs. 12 and 23). The Anderson bed crops out to the east and defines the eastern boundary of the Gillette coal field (Luppens and others, 2008). Of the 125.5 BST of original resource, about 101.8 BST is considered as avail able resources (tables 4-7). Depth to the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed, to about 2,000 ft near the axis of the basin; about 40 per cent of the available resource is at a depth less than 500 ft (fig. 55, table 5). The available resource percentage doubles to 89 percent for depths less than 1,000 ft. Of the total avail able resource, about 89 percent of the coal mineral estate is owned by the Federal government (table 6). The Anderson was included in the economic analysis to determine the coal reserve base. The Lower Anderson bed splits from the base of the Anderson coal bed. It is interpreted from 883 drill holes, has a maximum thickness of 44 ft and an average thickness of 4 ft (fig. 23). The coal bed is present in the north-central Wyoming PRB as small isolated areas extending into the south-central Montana PRB (fig. 56). Of the 3.4 BST of original resource, about 2.0 BST are considered as available resources (tables 4-7). Depth to the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed, to about 2,000 ft near the axis of the basin; about 42 percent of the available resource is at a depth less than 500 ft (fig. 57, table 5). Of the total available resource, about 90 percent of the coal mineral estate is owned by the Federal government (table 6). Dietz 1, Dietz 2, Dietz 3, and Dietz 4 Coal Beds The Dietz 1 coal bed was identified on 672 geophysical well logs, has a maximum thickness of 29 ft, and averages 4 ft thick (fig. 23). Dietz 1 coal thickness greater than 20 ft is limited to a small area in the northwest Wyoming PRB and small areas in the southwest Montana PRB (fig. 58). Of the 1.1 BST of original resource, only about 0.5 BST are considered as avail able resources (tables 4-7). Depth of the Dietz 1 coal bed ranges from shallow subcrop along the eastern extent of the bed, to about 2,500 ft along the axis of the basin (fig. 59, table 5). Identified in 930 drill holes, the Dietz 2 coal bed has a maximum thickness of 37 ft, and averages 6 ft thick (fig. 23). It is present in a small area in the Decker and Spring Creek Mines (fig. 12) in the Montana PRB, where it is mined along with the Dietz 3 (fig. 60). The Dietz 2 is also present in a small area in the north-central part of the Wyoming PRB. Of the 3.0 BST of original resource, about 2.0 BST are considered as available resources (tables 4-7). The Dietz 2 coal bed ranges in depth from shallow subcrop along the eastern extent of the bed, to more than 1,500 ft near the Decker and Spring Creek Mines (fig. 61, table 5). The Dietz 2 was included in the eco nomic analysis to determine the coal reserve base. The Dietz 3 coal bed is the thickest and most areally extensive of the Dietz coal beds. Interpreted from 4,816 drill holes, the Dietz 3 has a maximum thickness of 119 ft and an average thickness of 13 ft (fig. 23). The bed is present in two distinct areas; one near the Decker and Spring Creek Mines in the Montana PRB, where it exceeds a thickness of more than 40 ft, and the other in the north-central Wyoming PRB, where the bed attains a thickness of about 119 ft (fig. 62). Both northeast-trending and northwest-trending channels can be defined by observing where the bed thins and disappears, thus separating the bed into several pod-like areas. The combined Smith, Anderson, and Dietz 3 coal beds formed the most significant minable sequence of coals in the Decker and Spring Creek Mines (fig. 12). The Dietz 3 bed is a primary minable coal bed for the PSO lease area of Pittsburg and Midway Coal Mining Company (fig. 12). Of the 50.9 BST of original resource, about 45.1 BST are considered as available resources (tables 4-7). Of the total available resource, about 85 percent of the coal mineral estate is owned by the Federal government (table 6). Depth ranges from shallow subcrop along the eastern extent of the bed, to about 3,000 ft near the axis of the basin; about 29 percent of the available resource is at a depth less than 500 ft (fig. 63, table 5). The Dietz 3 was included in the economic analysis to determine the coal reserve base. The Dietz 4 coal bed is present in relatively small, isolated areas in the northwest part of the Wyoming PRB and in the area surrounding the Decker and Spring Creek Mines (fig. 12) in the Montana PRB (fig. 64). This bed was identified
22 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana on 624 geophysical well logs, reaches a maximum thickness of 20 ft and has an average thickness of 3 ft (fig. 23). Of the 1.8 BST of original resource, about 0.8 BST are considered as available resources (tables 4-7). Depth ranges from shal low subcrop along the eastern extent of the bed, to more than 3,000 ft along the axis of the basin (fig. 65, table 5). Upper Canyon/Cox, Canyon, and Lower Canyon Coal Beds The Upper Canyon coal bed is an upper split of the Canyon coal bed and correlates to the Cox coal bed identified by Haacke and others (2013) in the Montana PRB. Figure 66 shows that the subsurface extent is limited mostly to one large area in the west-central Wyoming PRB and small, isolated areas are in the south-central Montana PRB. The coal bed was identified on 725 geophysical well logs, has a maximum thickness of 31 ft, and averages 7 ft thick (fig. 23). Of the 6.0 BST of original resource, about 4.7 BST (86 percent) are considered as available resources and about 4.0 BST has Federal mineral ownership (tables 4-7). Depth of the coal bed ranges from shallow subcrop along the eastern extent of the bed, to more than 3,000 ft along the axis of the basin (fig. 67, table 5). The Canyon coal bed, originally named the Monarch in 1909, is equivalent to the Canyon coal bed of Baker (1929) (Law and others, 1979). Since 1929, it has been referred to as both the Canyon and the Monarch. The coal bed is present in much of the Wyoming PRB, extending northward into the southwest Montana PRB (fig. 68). The Canyon, along with the Anderson, is one of the principal CBM production targets in the Gillette coal field in the Wyoming PRB. Where the Anderson bed exceeds 60 ft thick in the Gillette coal field is where the Anderson and Canyon beds are a single thick bed (fig. 54). The Canyon bed was identified in 9,353 drill holes and reaches a maximum thickness of 183 ft, with an average thick ness of 21 ft (fig. 23). Of the 147.4 BST of original resource, about 135.4 BST are considered as available resources (tables 4-7). Of the total available resource, about 89 percent (120.3 BST) of the coal mineral estate is owned by the Federal government (table 6). Depth from the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed to more than 3,000 ft along the axis of the (fig. 69). About 19 percent of the available coal resource is at a depth of less than 500 ft (table 5). For the economic analysis, the Canyon was used in determining reserves. The Lower Canyon coal bed is a lower split of the Canyon coal bed. It was identified in 4,374 drill holes, has a maximum thickness of 85 ft, and averages 11 ft thick (fig. 23). The coal bed is present in a large area in the west-central Wyoming PRB and extends into the Decker and Spring Creek Mine area in the Montana PRB (fig. 70). About 52.0 BST of the 59.5 BST of original resource are considered as available resources (tables 4-7). Only about 12 percent of the available coal resource is at a depth less than 500 ft (fig. 71, table 5). Of the total available resource, about 83 percent (44.8 BST) of the coal mineral estate is owned by the Federal government (table 6). Depth ranges from shallow subcrop to more than 3,000 ft near along the axis of the basin (fig. 71). The Lower Canyon bed was included in the economic analysis to deter mine the coal reserve base. Upper Ferry and Ferry Coal Beds The Upper Ferry bed is an upper split of the Ferry coal bed and is present in a small area in the north-central Wyoming PRB (fig. 72). Based on 145 drill holes, it reaches a maximum thickness of 10 ft and has an average thickness of 4 ft (fig. 23). About 0.5 BST of the 0.8 BST of original resource are considered as available resources (tables 4-7). Depth to the top of the coal bed ranges from shallow sub crop to more than 1,500 ft near the center of the basin; about 0.1 percent of the available coal resource is at a depth less than 500 ft (fig. 73, table 5). The Ferry coal bed was identified in 744 drill holes and is limited in areal extent to the northwest part of the Wyoming PRB and the southwest Montana PRB (fig. 74). The bed has a maximum thickness of 28 ft and an average thickness of 5 ft (fig. 23). About 4.3 BST of the 6.4 BST of original resource are considered as available resources (tables 4-7). Of the total available resource, about 84 percent (3.4 BST) of the coal mineral estate is owned by the Federal government (table 6). Depth to the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed, to more than 3,000 ft along the axis of the (fig. 75). About 16 percent of the available coal resource is at a depth less than 500 ft (table 5). Werner/Cook Coal Bed The Werner/Cook bed, identified in 4,459 drill holes, has a maximum thickness of 90 ft and averages 13 ft thick (fig. 23). This is the oldest coal bed in the Wyodak-Anderson coal zone and is present in much of the Wyoming PRB, extending five townships northward into the Montana PRB (fig. 76). The Werner/Cook bed is known as the Werner coal bed in the Wyoming PRB and is equivalent to the Cook coal bed of Montana. The thickest part of the coal bed is present north of the Decker and Spring Creek Mines in the Montana PRB, where it exceeds a thickness of 60 ft. About 63.3 BST of the approximately 74 BST of original resource are consid ered as available resources (tables 4-7). Of the total available resource, about 88 percent (55.7 BST) of the coal mineral estate is owned by the Federal government (table 6). Depth to the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed, to about 2,500 ft along the axis of the basin (fig. 77). About 26 percent of the available coal resource is at a depth of less than 500 ft (table 5). The Werner/ Cook was included in the economic analysis to determine the coal reserve base. Upper Otter and Otter Coal Beds The Upper Otter bed is an upper split of the Otter coal bed and is present in small, isolated areas in the north-central Wyoming PRB (fig. 78). Based on 328 drill holes, it reaches a
Methodology 23 maximum thickness of 21 ft and has an average thickness of 4 ft (fig. 23). About 0.6 BST of the 0.9 BST of original resource are considered as available resources (tables 4-7). Of the total available resource, about 84 percent (0.5 BST) of the coal mineral estate is owned by the Federal government (table 6). Depth to the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed, to about 2,500 ft along the axis of the basin (fig. 79). About 0.6 percent of the available coal resource is at a depth less than 500 ft (table 5). Distribution of the Otter coal bed is shown in figure 80. Based on 3,642 drill holes, the bed reaches a maximum thickness of 170 ft and has an average thickness of 14 ft (fig. 23). Areas of greatest thickness occur in the center of the Wyoming PRB where the depth to the top of the bed is more than 1,500 ft. The Otter crops out along its northern extent and thins and eventually pinches out to the south and east. About 64.3 BST of the 71.0 BST of original resource are considered as available resources (tables 4-7). Of the total available resource, about 90 percent (58.0 BST) of the coal mineral estate is owned by the Federal government (table 6). Depth to the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed, to about 2,500 ft along the axis of the basin (fig. 81). Only about 5.5 percent of the available coal resource is at a depth less than 500 ft (table 5). Gates/Wall Coal Bed Known as the Gates bed in Wyoming and the Wall bed in Montana, this bed is present in a large area in the central and northern Wyoming PRB, extending into the southwestern Montana PRB (fig. 82). The Gates/Wall crops out along its northern extent and thins and pinches out to the south and east. Identified in 3,412 drill holes, the coal has a maximum thickness of 125 ft, and averages 9 ft thick (fig. 23). About 57.9 BST of the 66.4 BST of original resource are considered as available resources (tables 4-7). Of the total available resource, about 86 percent (49.8 BST) of the coal mineral estate is owned by the Federal government (table 6). The top of the coal bed ranges from shallow subcrop along the eastern extent of the bed, to more than 3,000 ft along the axis of the basin (fig. 83). About 8 percent of the available coal resource is at a depth less than 500 ft (table 5). Pawnee Coal Bed The Pawnee coal bed is present in the northern Wyoming PRB and extends into the southern one-half of the Montana PRB (fig. 84). The Pawnee crops out along its northern extent and thins and pinches out to the south and east. The coal bed was identified in 1,368 drill holes, has a maximum thickness of 34 ft, and averages 7 ft thick (fig. 23). About 17.0 BST of the 24.5 BST of original resource are considered as available resources (tables 4-7). Of the total available resource, about 85 percent (14.5 BST) of the coal mineral estate is owned by the Federal government (table 6). Depth to the top of the coal ranges from shallow subcrop along the eastern extent of the bed, to more than 3,000 ft near the axis of the basin. About 30 percent of the available coal resource is at a depth less than 500 ft (fig. 85, table 5). In the Montana PRB there is significant area of thick coal less than 500 ft in depth, which is potentially surface minable (fig. 85). Brewster-Arnold Coal Bed The Brewster-Arnold coal bed, identified in 110 drill holes, has a maximum thickness of 19 ft and averages 5 ft thick (fig. 23). This coal bed is present mostly in the cen tral Montana PRB and small isolated areas in the Wyoming PRB (fig. 86). About 0.5 BST of the approximate 2.0 BST of original resources are considered as available resources (tables 4-7). Of the total available resource, about 0.3 BST of the coal mineral estate is owned by the Federal government (table 6). Depth to the top of the coal ranges from shallow sub crop along the eastern extent of the bed, to more than 1,500 ft along the axis of the basin (fig. 87, table 5). Odell Coal Bed Identified in 1,052 drill holes, the Odell bed is present in the northern Wyoming PRB and extends into the southern Montana PRB (fig. 88). The bed has a maximum thickness of 26 ft, and averages 4 ft thick (fig. 23). Of the 11.7 BST of original resource, about 6.6 BST are considered as available resources (tables 4-7). Of the total available resource, about 85 percent (5.7 BST) of the coal mineral estate is owned by the Federal government (table 6). Depth to the top of the coal ranges from shallow subcrop along the eastern extent of the bed, to more than 3,000 ft along the axis of the basin (fig. 89, table 5). Cache Coal Bed The Cache bed is present primarily in the southern Montana PRB (fig. 90). The bed, which was identified on 247 drill holes, reaches a maximum thickness of 26 ft, and has an average thickness of 3 ft (fig. 23). Of the 3.3 BST of original resource, about 0.8 BST are considered as available resources (tables 4-7). Of the total available resource, about 0.7 BST of the coal mineral estate is owned by the Federal government (table 6). Depth to the top of the coal ranges from shallow subcrop along the eastern extent of the bed, to more than 2,000 ft along the axis of the basin (fig. 91, table 5). A Zone Coal Bed The A Zone bed is correlated in several drill holes in a cross section by McLellan and others (1990) and is present only in small isolated areas in the Montana PRB (fig. 92). The bed, identified in 24 drill holes, has a maximum thickness of 9 ft and averages 3 ft thick (fig. 23). Of the 0.1 BST of original resource, about 0.01 BST are considered as available resources (tables 4-7). Depth ranges from shallow subcrop along the eastern extent of the bed, to about 1,000 ft along the axis of the (fig. 93, table 5).
24 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Upper Rosebud and Rosebud/Knobloch Coal Beds Identified in 44 drill holes, the Upper Rosebud is an upper split of the Rosebud/Knobloch coal bed and is present in a small area near the Absaloka Mine (fig. 12) in the Montana PRB (fig. 94). The Upper Rosebud is referred to as the S1 coal bed by the Westmoreland Resources, Inc. Mining Company (J. Speake, Jr., Westmoreland Resources, Inc., oral commun., 2010). The bed has a maximum thickness of 15 ft and aver ages 3 ft thick (fig. 23). Of the 0.2 BST of original resource, about 0.05 BST are considered as available (tables 4-7). Depth to the top of the bed ranges from shallow subcrop along the eastern extent of the bed, to about 1,000 ft along the axis of the basin (fig. 95, table 5). The Rosebud/Knobloch coal bed is one of the thickest minable coal beds in the Montana PRB. The bed is known as the Rosebud west of Rosebud Creek and as the Knobloch east of Rosebud Creek (fig. 96) (Haacke and others, 2013). The Rosebud/Knobloch is equivalent to the Deep 1 coal bed in the SWPRB (Osmonson and others, 2011) and correlates to the Rosebud coal bed of Roberts and others (1999c) and the Sawyer coal bed of McLellan and others (1990). Near the town of Ashland, the Rosebud/Knobloch correlates to the Calvert and the McKay/Nance coal beds of Roberts and others, (1999a). This coal is mined in the Rosebud and Absaloka Mines and was also mined at the abandoned Big Sky Mine (fig. 12). Identified in 2,203 drill holes, the coal bed has a maxi mum thickness of 73 ft, and averages 12 ft thick (fig. 23). Some of the thickest coal is located under the Custer National Forest (fig. 19). This bed is the minable bed target for the Otter Creek lease area (fig. 12). In the Montana PRB, the Rosebud/ Knobloch crops out along Otter Creek and pinches out to the east and west. About 47.1 BST of the 64.4 BST of original resource are considered as available resources (tables 4-7). Of the total available resource, about 80 percent (37.4 BST) of the coal mineral estate is owned by the Federal government (table 6). Depth to the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed, to about 1,500 ft in the Montana PRB and about 4,000 ft along the axis of the basin in the Wyoming PRB. About 27 percent of the available coal resource is at a depth less than 500 ft (fig. 97, table 5). The Rosebud/Knobloch was included in the economic analysis to determine the coal reserve base. Calvert Coal Bed Present only in the Montana PRB, the Calvert coal bed was identified in 86 drill holes, has a maximum thickness of 18 ft and averages 3 ft thick (fig. 23). Near the town of Ashland (fig. 1) the bed is part of the base of the Rosebud/ Knobloch (fig. 98) (Roberts and others, 1999a). About 0.2 BST of the 1.2 BST of original resource are considered as avail able resources (tables 4-7). Depth to the top of the coal ranges from shallow subcrop along the eastern extent of the bed, to about 2,000 ft deep along the axis of the basin (fig. 99, table 5). McKay/Nance and Lower McKay Coal Beds The McKay/Nance coal bed is a lower split of the Rosebud/Knobloch coal bed. The thickest portion of the Rosebud/Knobloch coal bed east and south of the town of Ashland (figs. 1 and 96) reflects the area where the Rosebud/ Knobloch and McKay/Nance coal beds form a single bed. The McKay/Nance coal bed splits off the Rosebud/Knobloch coal bed peripherally from the thickest area of the Rosebud/ Knobloch coal bed (fig. 100). This split results in a corre sponding thinning of the Rosebud/Knobloch coal bed in all directions. In the Montana PRB, the McKay/Nance coal bed is known as the McKay coal bed west of Rosebud Creek and the Nance coal bed east of Rosebud Creek (Roberts and others, 1999c). The bed is present in both the Rosebud and Absaloka Mines, and the abandoned Big Sky Mine areas (figs. 12 and 100). The McKay/Nance crops out along its northern extent and thins to the east, south and west (fig. 100). The coal bed is also present throughout the Wyoming PRB, but at considerably greater depth. The McKay/Nance coal bed is equivalent to the Deep 2 coal bed identified in the SWPRB (Osmonson and others, 2011). The coal bed was identified in 2,499 drill holes, has a maximum thickness of 36 ft, and averages 5 ft thick (fig. 23). Of the 33.3 BST of original resource, about 22.6 BST are considered as available resources (tables 4-7). Of the total available resource, about 78 percent (17.7 BST) of the coal mineral estate is owned by the Federal government (table 6). Because of a topographic high (Little Wolf Mountains) (fig. 101), depth to the coal bed ranges from shallow subcrop along the eastern extent of the bed, to more than 2,000 ft between the Absaloka and Rosebud Mines (figs. 12 and 101). About 20 percent of the available coal resource is at a depth less than 500 ft (fig. 101, table 5). The Lower McKay bed, identified in 63 drill holes, has a maximum thickness of 7 ft and averages 3 ft (fig. 23). The coal bed is present only in small areas near the Absaloka Mine in the Montana PRB (figs. 12 and 102). The Lower McKay is also referred to as the S2 coal bed by Westmoreland Resources, Inc. (J. Speake, Jr., Westmoreland Resources, Inc., oral commun., 2010). Of the 0.2 BST of original resource, about 0.01 BST are considered as available resources (tables 4-7). Depth to the top of the coal bed ranges from shal low subcrop along the eastern extent of the bed, to more than 1,500 ft (fig. 103, table 5). Flowers-Goodale Coal Bed The areal extent of the Flowers-Goodale is present in both the Montana and Wyoming PRB assessment areas (fig. 104). In the Montana PRB, the Flowers-Goodale bed crops out along the northern and eastern limits of its extent. Several lenticular pods of the bed are present in the central Wyoming PRB. In Wyoming, this bed is equivalent to the Deep 3 coal bed (Osmonson and others, 2011). Identified in 2,752 drill holes, this bed occurs in a large area in the southern one-half of the Montana PRB and throughout the central part of the Wyoming PRB (fig. 104).
Methodology 25 The bed has a maximum thickness of 40 ft and averages 8 ft thick (fig. 23). Of the 60.5 BST of original resource, about 51.0 BST are considered as available resources (tables 4-7). Of the total available resource, about 85 percent (43.4 BST) of the coal mineral estate is owned by the Federal government (table 6). Depth to the top of the coal bed ranges from shal low subcrop along the eastern extent of the bed, to more than 3,000 ft in depth near the axis of the basin. About 12 percent of the available coal resource is at a depth less than 500 ft (fig. 105, table 5). The Flowers-Goodale was included in the economic analysis to determine the coal reserve base. Upper Witham and Robinson/Witham Coal Beds The Upper Witham coal bed has limited areal extent and is present only in the Montana PRB near the abandoned Big Sky Mine (fig. 106). Identified in 150 drill holes, the bed reaches a maximum thickness of 29 ft and has an average thickness of 4 ft (fig. 23). Of the 0.1 BST of original resource, about 0.07 BST are considered as available resources (tables 4-7). Depth to the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed, to about 500 ft near the abandoned Big Sky Mine (figs. 12 and 107, table 5). The Robinson/Witham is known as the Robinson coal bed west of Rosebud Creek and as the Witham coal bed east of Rosebud Creek in the Montana PRB (fig. 108). The bed crops out north of the Rosebud Mine (fig. 12), was identified in 1,491 drill holes, has a maximum thickness of 41 ft, and aver ages 7 ft thick (fig. 23). The bed is also found in a large area in the west-central part of the Wyoming PRB and correlates with the Robinson coal bed of Roberts and others (1999c). Of the approximate 20.7 BST of original resource, about 15.0 BST are considered as available resources (tables 4-7). Of the total available resource, about 65 percent (9.9 BST) of the coal mineral estate is owned by the Federal government (table 6). Because of a topographic high (Little Wolf Mountains) (fig. 108), depth to the top of the coal bed ranges from shal low subcrop to more than 3,000 ft between the Absaloka and Rosebud Mines (fig. 12). About 30 percent of the available coal resource is at a depth less than 500 ft (fig. 109, table 5). Roberts/Terret Coal Bed The Roberts/Terret coal bed, identified in 1,768 drill holes, is present throughout much of the central part of both the Montana and Wyoming PRB (fig. 110). This bed cor relates with the Roberts coal bed in Wyoming (Molnia and Pierce, 1992) and in the NWPRB assessment area of Scott and others (2010). The bed reaches a maximum thickness of 42 ft, and averages 8 ft thick (fig. 23). Of the 51.9 BST of original resource, about 44.5 BST are considered as available resources (tables 4-7). Of the total available resource, about 84 percent (37.1 BST) of the coal mineral estate is owned by the Federal government (table 6). Depth to the top of the Roberts/Terret coal bed ranges from shallow subcrop along the eastern extent of the bed, to more than 4,000 ft near the axis of the basin (table 5, fig. 111). Burley Coal Bed Identified in 50 drill holes, the Burley coal bed is present in two small areas in the Montana PRB and one isolated area in the Wyoming PRB. The largest area in the Montana PRB is near the Otter Lease, the other is south of the Rosebud Mine (figs. 12 and 112). The bed has a maximum thickness of 10 ft and averages 3 ft thick (fig. 23). Of the 1.6 BST of original resource, about 0.7 BST are considered as available resources (tables 4-7). The depth to the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed, to more than 2,000 ft along the axis of the basin (fig. 113, table 5). Upper Stag and Lower Stag Coal Beds The Stag coal bed is correlated in several drill holes in a cross section in McLellan (1991). The name was expanded in this report to include an Upper and Lower Stag for correlating two minor coal beds. The Upper Stag bed is limited in areal extent to the northern Wyoming PRB extending into the south ern Montana PRB (fig. 114). The bed, which was identified on 91 well logs, reaches a maximum thickness of 13 ft, and has an average thickness of 3 ft (fig. 23). Of the approximate 1.9 BST of original resource, about 0.8 BST are considered as available resources (tables 4-7). Depth to the top of the coal bed ranges from shallow subcrop along the eastern extent of the bed, to more than 3,000 ft along the axis of the basin (fig. 115, table 5). The Lower Stag bed is present in small, isolated areas in the southern Montana PRB (fig. 116); this bed is the lowest (oldest) coal bed evaluated in the PRB. The bed, which was identified on 8 well logs, reaches a maximum thickness of 6 ft and has an average thickness of 3 ft (fig. 23). Of the 0.2 BST of original resource, about 0.01 BST are considered as avail able resources (tables 4-7). Depth to the top of the coal bed ranges from shallow subcrop to more than 2,000 ft along the axis of the basin (fig. 117, table 5). Coal Bed Cross Sections Three cross sections (figs. 8-10) illustrate some of the more important features of the coal bed geometry in the PRB. The west-east, dip-oriented section labeled A-A' (fig. 8) illus trates the stratigraphic relation between the thick Anderson/ Canyon beds in the Gillette coal field to the thick Smith bed in the SWPRB area and the rapid splitting and thinning of the coal beds towards the western edge of the basin. In response to the Bighorn Mountains uplift along the western margin of the basin, several northeast-trending faults developed and terminated the coal beds from cropping out along the western margin of the basin (Ellis and Colton, 1994). Previous studies (Molnia and Pierce, 1992; Flores and others, 2010) correlated the Anderson/Canyon beds with the Smith coal bed; however, the large volume of new data for the current assessment pro vided sufficient control to confirm that these two coal beds are not equivalent (Luppens and others, 2008; figs. 16 and 17). A comparison of the Anderson bed isopach maps from the 2002
26 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana and 2008 coal assessments (Ellis and others, 2002; Luppens and others, 2008) illustrate the substantial differences in coal bed correlations afforded by the abundance of additional data. This revised interpretation is supported by several other recent studies. Ashley (2005) and Jones (2010b) have both correlated the Anderson/Canyon and the Smith (Big George) as separate coal beds. Cross section C-C′ from Jones (2010b) is remarkably similar the A-A′ cross section in this report (fig. 8). The revisions of the thick coal bed correlations within the Wyodak-Anderson coal zone have several ramifications. Rather than the Anderson and Smith beds (Big George) being a single continuous, thick bed as shown in figure 17, there is an interval in figure 8 where the Smith, Anderson, and Canyon coal beds are all relatively thin. The new correlations effec tively result in a downdip, geological barrier to westward advances of surface mining of the thick Anderson/Canyon beds in the Gillette coal field (Luppens and others, 2008). Several other important features of coal bed geometry in the PRB can also be observed in these three cross sections (figs. 8-10). The west-east, dip-oriented section B-B′ (fig. 9) through the northern portion of the NWPRB assessment area illustrates both the asymmetric nature of the basin and the thickening of the Wyodak-Anderson coal zone northward relative to the A-A′ cross section (fig. 8) through the Gillette coal field and SWPRB assessment area. In addition to the thickening of the Wyodak-Anderson coal zone, the thick coal beds in the Gillette coal field and the SWPRB assessment area split farther northward. Thinner coal beds spread over a larger stratigraphic interval and present a different set of mining conditions than currently found in the Gillette coal field where the thick, relatively shallow Anderson and Canyon beds are currently mined. The northwest-southeast, strike-oriented section C-C′ (fig. 10) demonstrates the splitting and thinning of the thick Anderson and Canyon coal beds and an overall increase in thickness in the Wyodak-Anderson coal zone northward from the Gillette coal field into the NWPRB and MTPRB assess ment areas. The Wyodak-Anderson coal zone is limited to the southernmost portion of the MTPRB where these beds crop out. Locally, thicker parts of coal beds below the WyodakAnderson coal zone (Rosebud/Knobloch, Flowers-Goodale, and Pawnee) crop out farther to the north. Another important factor in the coal bed geometry is that any differences in the hydrochemistry of produced water may be explained by the updated correlations described in this report. For example, the Anderson (Big George) was previ ously assumed to be the same thick coal bed; however, in this assessment it was determined that the Anderson and the Big George are separate thick coal beds (Luppens and others, 2008) (figs. 8, 17, and 18). In-Place Coal Resource Volumetrics Calculation of coal resource volumetrics first requires converting the surface topography and coal thickness, roof, and floor grids for each coal bed from the final PRB geological model to ASCII grids. Using ArcView (Environmental Systems Research Institute, 2006), USGS in-house GIS resource allocation planning (RAP) scripts were developed to apply the appropriate density value to the coal thickness grids to calculate the tonnage of coal contained within each assessed area. Finally, additional RAP scripts were used to apply the original, remaining, and available coal tonnages to the grids of coal ownership, reliability categories, depth to coal, and assessment areas to create an even more detailed analysis of the assessment area's coal resources. Original coal resources were calculated for all coal beds at least 2.5 ft thick and with no restrictions applied. Remaining resources were calculated using the volume of the original resource minus the volume of coal that had been mined. Land-use environmental) and technical restrictions were then calculated and subtracted from the remaining resource to determine available resources. A total of 47 coal beds were identified during this final assessment. With no restrictions applied, the total original resource for these 47 beds was calculated to be about 1.16 trillion short tons (TST) (fig. 23, tables 4-7). Available coal resources, which are part of the original coal resource after subtracting restrictions to mining and areas of burned coal, were calculated to be 975 BST. Restrictions included railroads, Federal Interstate highways, urban areas, alluvial valley floors, State parks, national forests, and mined coal areas. Figure 118 provides the amount and percent of origi nal coal resources for 12 significant coal beds with about 50 BST resources or greater. Of these 12 beds, 6 are within the Wyodak-Anderson coal zone (Smith, Anderson, Dietz 3, Canyon, Lower Canyon, and Werner/Cook). Collectively, the Wyodak-Anderson coal zones represent 50 percent of the total original in-place resources. The 12 major coal beds total about 81 percent of the original resources with the remain ing 35 assessed beds totaling about 19 percent of the original resources. These 12 beds offer the most potential for recover able coal resources. The total coal resource number of 1.16 TST is about 0.09 TST greater than the sum of 1.07 TST of original resources of the four assessment areas (Scott and Luppens, 2013). The inclusion of deeper coal beds below the WyodakAnderson coal zone for this report, especially in the Gillette coal field, East Gillette coal field extension, and NWPRB assessment areas, accounted for the increase in this final inplace resource estimate. Tables 4-7 provide resource summaries based on reliabil ity, overburden thickness, coal ownership, and assessment area categories. Table 8 presents the summary results of tables 4-7 to facilitate comparisons of the different coal resource catego rizations. About 6.5 BST of the original resource was estimated to be burned (clinker) and 6.4 BST was previously mined, leav ing a remaining resource of about 1.15 TST. Approximately 174 BST (15 percent) of the original resource is affected by restrictions (mined coal, too thin, land use, and technical). Subtraction of these restrictions from the 1.15 TST leaves about 975 BST (84 percent) of the original resource available for potential development in the PRB (tables 4-7). The same set of coal resource summaries are included in each of the four
Methodology 27 PRB area assessments if more detailed information is needed (Luppens and others, 2008, Scott and others, 2010, Osmonson and others, 2011, Haacke and others, 2013). Coal resources for the 47 assessed coal beds are reported by reliability categories in tables 4, 8, and 9. The resources were classified according to geologic assurance of existence or reliability, which are dependent on the density of geologic data points. The different reliability categories— measured (0.25 mi from point of measurement); indicated (0.25-0.75 mi from point of measurement); inferred (0.75-3.0 mi from point of measurement); and hypothetical (greater than 3.0 mi from point of measurement)—were established on the basis of distance from a data point (Wood and others, 1983). About 76 percent of the original resources for all assessed beds can be classified as measured or indicated (table 9). About 99 percent of the original resources are in the measured, indicated, or inferred categories (table 9). This reflects a much higher relative degree of confidence than previous studies as a result of the substantial amount of new data incorporated into this assessment. Table 9 compares PRB resources in Ellis and others (1999) with resources in this assessment as well as a comparison of the total resources and reliability catego rizes. The resources in the measured and indicated categories increased from 38 to 78 percent with a corresponding three fold decrease in the inferred and hypothetical categories from the 1999 assessment to the current assessment. It is interesting to note that the difference between the total esti mated resource volumes for the two PRB assessments of the Wyodak-Anderson coal zone (table 9) was only about 16 BST. Thus, reasonable total coal resources can be estimated with less data using a net thickness isopach for a coal zone. How ever, more data were needed to confidently correlate the individual coal beds given the complex coal geology within the PRB if estimates of recoverable coal are required. An example of this revised coal bed correlation is shown in figures 16 and 17. Although the net total resources for the area represented in the two figures are similar, figure 17 represents a significantly different stratigraphic and mining economics scenario than figure 16. Coal resources for the 47 assessed coal beds are reported by overburden depth categories in tables 5 and 8. Nearly 90 percent of the available resources are less than 2,000 ft in depth. Only 22 percent of the resources are less from 0 to 500 ft in depth, which is the interval where most of the current coal resources in the reserves category would be expected. Coal resources for the 47 assessed coal beds are reported by ownership categories in tables 6 and 8. Eighty-six percent of the available coal resources are under Federal coal owner ship for the greater PRB. South of T. 4 S. in Montana, the Federal coal ownership exceeds 90 percent (fig. 20). North of T. 4 S. in Montana, Federal coal ownership is less than 50 percent in most townships. In July 1864, the Northern Pacific Railroad was chartered (Malone and others, 1991) and the U.S. Government used a portion of the public domain (Federally owned land) to assist and encourage the building of transcontinental railroads. This land was granted in alternate sections, creating a checkerboard pattern, within an area lying 40 mi on either side of the pro posed Northern Pacific Railroad right of way (fig. 20). Coal resources for the 47 assessed coal beds are reported by assessment area in tables 7 and 8. Of the four assessment areas, the MTPRB assessment area contains the least amount of available resources. The dominant Wyodak-Anderson coal zone is limited to the southernmost four townships in Montana. Coal beds in the Wyodak-Anderson coal zone are much thinner in Montana relative to those beds in the Gillette coal field and SWPRB assessment area. The Werner/Cook bed, at the base of the Wyodak/Anderson coal zone, crops out in the southern one-half of Big Horn and Powder River Counties (fig. 76). Perspectives on Environments of Deposition The primary goal of this assessment was to quantify and evaluate coal resources in the Powder River Basin. However, it is difficult to assess the coal beds in the PRB without specu lating on the depositional history of such thick, extensive coal beds. Mapping of individual beds for the first time through out the entire PRB was required to complete the economic assessment of in-place as well as recoverable coal resources. The correlation of the discrete coal beds in this assessment offers more information than simply the coal bed isopach maps needed for the coal resource inventory. The individual bed maps also enable the generation of interburden isopach maps between adjacent coal beds which provides the ability to investigate patterns of clastic deposition between periods of peat accumulation. The purpose of this section was not to revise depositional models, but to review several theories and to briefly discuss how the results of this assessment may provide new perspectives regarding depositional environments of the extraordinary PRB coal province. Several depositional models have been proposed to explain the origin of the thick coal beds in the PRB. These models attribute the development of accommodation and the nature of coal splitting (parting geometry) to sedimentary processes (differential compaction, channel switching, and crevasse splay deposits) within specific depositional environ ments (raised mires, deltas, and basinwide wetlands) (Jones, 2010a). Most of these models are based on peat-to-coal compaction ratios ranging from 3:1 to 20:1 (3-20 ft of peat compacts to form 1.0 ft of coal). Jones (2010a), however, proposes that sequence stratigraphy of coal beds and base ment-related structural effects explain the origin of these thick coal deposits. Flores and others (1999) proposed that the coal in the Fort Union Formation formed from peats that accumulated in swamps of northeast flowing fluvial systems. The sedi ments that formed these rocks were deposited in channels, overbank floodplains, floodplain lakes, and crevasse channel splays drained by meandering, anastomosing, and braided streams. Thick, low-ash, low-sulfur coal beds of the Tongue River Member formed in raised swamps that developed in
28 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana interfluvial environments and on abandoned stream deposits. The regional paleogeographic patterns of the merged coal zones appear to be affected by peat deposition on noncom pactable, sandstone-dominated, alluvial-belt deposits super imposed on paleotectonic platforms. The lateral migration, avulsion, and abandonment of these platforms resulted in random distribution of the merged coal bodies (Flores and others, 2010). Several of these channel systems were mapped in the Gillette coal field by Luppens and others (2008). Some channel locations can be seen on the drill hole location map (fig. 15) as areas of less dense drilling, because of relatively thin or absent coal beds in these channel areas. Examination of geophysical logs delineated a major basin-axis channel system. This channel system extends northward from T. 40 N., R. 73 W. (fig. 15). A relatively narrow, east-west trending channel can also be seen by the lack of drilling from T. 46 N., R. 71 W., west about three townships until it intersects the north-south channel system on the west side of the Gillette coal field (fig. 15). Ayers (1986b) proposed a fluvial deltaic model where sediments filled the basin, primarily from the eastern margin, in a series of northeast southwest-trending delta systems with thick coal beds forming in an interdeltaic setting. Ayers and Kaiser (1984) stated that there is no evidence for a basin-axis fluvial system, as suggested by previous research (Flores, 1982), as sand percentages are lowest along the axis of the basin. However, using geophysical logs, Luppens and others (2008) defined a channel system parallel to the basin axis. Furthermore, the split line between the Canyon and Anderson beds, especially in the south portion of the Gillette coal field, is also oriented to the basin axis with the split thickening westward. This basin-axis fluvial system and associated split geometry is perpendicular to the deltaic sand body framework geometry which trends northeast southwest (Ayers, 1986b). An important factor regarding the deltaic models is the concept of peat compaction (Jones, 2010a). The raised mires model and the interdeltaic wetlands model both need tremen dous amounts of accommodation to allow for great thicknesses of peat to accumulate. These models are based on the concept of peat-to-coal compaction ratios, wherein a given amount of peat is compressed to form a given thickness of coal. An alternate hypothesis has been proposed to explain the genesis of the thick PRB coal sequences, based on chronostratigraphic correlation (sequence stratigraphy) of coal beds, basement-related structural effect on differential development of accommodation within the basin, and the coalification process (not compaction) (Jones, 2010a). Recur rent movement along postulated basement faults resulted in stacked organic deposits, alternating organic and clastic deposits, and heterogeneous clastic deposits. Subtle changes in surface topography resulting from structural movement of these basement blocks disrupt the process of peat accumula tion by changing the water table, shifting fluvial systems, and affecting the stabilization of shorelines. Jones (2010a) provides evidence that the thick PRB coal deposits are not a result of organics that accumulated in single, long-lived, stable wetlands; rather, these coal deposits are composed of numerous, stratigraphically adjacent coal beds that developed intermittently between periods of organic accumulation and periods of nondeposition and weathering. A key to this depositional concept is the coalification pro cess. As peat accumulates, it undergoes progressive aerobic to anaerobic bacterial decay with depth. The end product of this bacterial reduction of accumulated plant material is a dark brown to black, semi-amorphous, organic-rich gel, known as gotta. During periods of subaerial exposure, the layer of partially decomposed peat is readily oxidized and prone to erosion when dried and thus, is often not preserved. Data that support subaerial exposure of the gotta include thin paleosols such as fusain layers (discrete horizons of oxidized coal), evaporate minerals (for example gypsum and anhy drite), and variable ash content of the coal above and below the thin oxidized surfaces. The bottom and top of these paleosols mark periods between different depositional facies, and the spacing of these chronostratigraphic surfaces (time lines) represents equal amounts of time. These time lines are important because they indicate that thick coal deposits did not form from a singularly thick deposit of peat, but that thick coal deposits actually formed from numerous, stacked, thinner accumulations of gotta. The thickness of a coal bed generally corresponds to the final cumulative thickness of the relatively incompressible gotta layers. The heat-driven process (thermogenesis) converts the gotta to various grades of coal (Jones, 2010a). A lineament-based depositional model is summarized in figures A and B contained in a report by Jones (2010a). In this model, organic accumulation in a lower energy wetland environment supported subaqueous reducing conditions. Subsequent development of differential accommodation because of fault reactivation of basement blocks occurred along split lines. A period of high energy, localized clas tic deposition occurred in the downthrown blocks, while topographically higher blocks were subjected to subaerial exposure and oxidation of the gotta surface. Repetition of the differential development of the accommodation pro cess resulted in the unique geometry of coal deposits in the Tongue River Member of the Fort Union Formation in the PRB (fig. B in Jones, 2010a). To test this model, several individual coal bed isopach maps, a combined isopach map of the major Wyodak-Anderson zone beds (Canyon, Anderson, and Smith), and an isopach of the interburden between the Anderson and Canyon coal beds were examined to see if there is a relation between coal thickness trends and lineament orientation trends in the basin. The isopach maps for the Flowers-Goodale and Roberts/Terret coal beds and superimposed lineaments are shown in fig ures 119 and 120. Interburden between these two beds ranges from about 125 to 200 in thickness. Flores (2010) States that the thicker (merged) coal bodies are randomly distributed.
Surface Coal Resource Assessment 29 However, several of the thicker areas of coal in both beds overlie each other. They are generally bounded by the north west-trending Buffalo/Douglas, Lightning Creek, and Black Butte lineaments, and the southwest-trending Casper/Bill, Fiddler Creek, South Coyote Creek, and Rozet lineaments, suggesting some structural effect. The isopach map of the Smith, Anderson, and Canyon coal beds, with superimposed lineaments, is shown in fig ure 121. The thickness distribution appears to be controlled by the northwest-trending Buffalo/Douglas, Lightning Creek, and Black Butte lineaments, and the southwest-trending Fiddler Creek, Rozet, Tensleep/Harding, and Big Horn/Custer lineaments, which again suggests some structural influence. There also seems to be structural control affecting areas of little or no coal accumulation or "want areas" (Flores, 2010). This want area, bounded by the southwest-trending Tensleep/ Harding and Big Horn/Custer lineaments (fig. 121), coincides with the marked thickening of the Wyodak-Anderson coal zone interval, as well as the splitting and thinning of the coal beds within that zone just south of the Montana State line. By mapping individual coal beds rather than net coal isopachs, the generation of interburden isopachs can be accomplished by subtracting the roof elevation grid of a lower bed from the floor elevation grid of an upper bed. When a coal bed splits, the net thickness of the two splits may be similar to the unsplit coal bed. Therefore, relying on net coal isopachs may mask the split line orientation of the parting between the two coal beds. Interburden isopachs can define the parting geometry. The interburden isopach between the Anderson and Canyon beds in the Gillette coal field (Luppens and others, 2008) and the superimposed lineaments is shown in figure 122. The parting orientation in the southern portion of the coal field is parallel to the northwest-trending Lightning Creek linea ment. The parting split line in the northern part of the coal field coincides with the Rozet lineament. The east-west parting in the central part of the coal field (T. 46 N. and T. 47 N.) is a fluvial channel system that splits the merged coal bed. This channel system is parallel to the Sussex/Osage lineament (fig. 122). Flores (2010) stated that this east-west "want" area was not parallel to lineament trends. However, that appraisal was based on a net coal isopach map with less data control than the current assessment, which precluded definitive orien tation of the channel system. Surface Coal Resource Assessment The objective of the USGS Coal Assessment Project is to refine the Nation's coal resource estimates and conduct the systematic determination of the coal reserve base on a regional basis in the major coal provinces in the Nation. The final and most important step in the coal assessment process is to derive estimates of that portion of in-place resources that can currently be classified as reserves and those resources that are potentially recoverable based on economic analyses. Regional estimates of coal reserves can provide energy planners a more meaningful appraisal of the amount of coal that is potentially recoverable in the foreseeable future. Therefore, the develop ment of a regional mining economics model for each of the four assessment areas is essential to accomplish the goals of the PRB coal assessment. Surface Mine Modeling Developing regional mine models is challenging because there are significant differences in the coal geology between the Gillette coal field (Luppens and others, 2008) and the other assessment areas within the PRB, which can appreciably affect the economic analysis. Mine engineering practices must be adapted to specific geologic conditions. Therefore, the mine modeling methodology was customized for each of the four PRB assessment areas. Despite geologic variations between assessment areas, a common methodology was followed (fig. 14). Replicating all assessment methodologies in this report would be impractical, but the individual PRB assess ment reports include specific mine modeling details (Luppens and others, 2008; Scott and others, 2010; Osmonson and others, 2011; Haacke and others, 2013). The USGS developed both surface and underground regional mine models for the assessment areas because there are significant areas within the PRB that are underlain by thick, deep, coal beds that are not amenable to surface min ing recovery. Although no coal in the PRB is currently nor is anticipated to be recovered by underground mining in the fore seeable future, it was determined that for a holistic assessment of the coal resources in the PRB, underground mining should be evaluated at least on a preliminary basis. Geologic Aspects of Surface Mine Model Development Bed thickness is one of the most important factors affect ing coal recoverability; thin coal beds may be unrecoverable. There is a significant inverse relationship between bed thick ness and the mining disturbance area (Luppens and others, 2009). A 4-ft bituminous coal bed requires 22.1 mi2 for a 100 million-ton resource block, whereas a 50-ft bed requires only 1.8 mi2. Clearly, it would be preferable to recover the thickest coal bed. However, coal bed thickness is not the only important criterion affecting coal recoverability. The depth of a coal bed also affects coal recovery eco comics, especially for surface minable resources. The most important cost component in surface mining is the expense of removing the volume of rock above a minable coal bed (overburden) (Luppens and others, 2009). The cost of surface coal mining increases with increased depth because of the greater volume of material that needs to be removed per unit of coal. The relation between coal bed depth and thickness is
30 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana referred to as the stripping ratio, which is the most significant economic factor in the evaluation of surface mining potential (Luppens and others, 2009). This ratio represents the volume of rock both above and within (parting) coal beds expressed by the number of cubic yards that must be mined to obtain one ton of coal. Although not an exact conversion, the stripping ratio can be estimated by dividing the thickness of the rock above the coal bed by the coal thickness. For example, given a 10-ft-thick coal bed and a 50-ft-thick bed, both at 100 ft depth, the approximate stripping ratios would be 10:1 and 2:1, respectively. Therefore, for the 2:1 stripping ratio area only 2 cubic yards (yd3) of rock would have to be removed per ton of coal produced, compared to 10 yd3 for the 10:1 area. Obviously, the 2:1 ratio area would have a significant produc tion cost advantage. It is the combination of extensive, thick, relatively low stripping ratio resources, coupled with relatively low-sulfur and low-ash content in the PRB that has stimulated the rapid development in this region during the past 40 years. A maximum stripping ratio of 10:1 was used for the economic analyses. While a stripping ratio of 10:1 is higher than current (October 2014) average mining conditions in the PRB (typi cally less than 4:1 or less ratio), mining to 10:1 stripping ratios have been reported elsewhere in the United States (Schobert, 1995; Kaiser, 1999). Modeling Stratigraphic Sequence for Surface Mining The first step in conducting a mining economic evalu ation is deciding which coal beds to include in the mine models and then parsing out the coal resources by composite stripping-ratio increments. The criteria used to select coal beds for the mine models were depth, thickness, and areal extent. Generally, only beds with an areal extent of at least several townships, thicknesses 5.0 ft or greater, and depths less than 500 ft were evaluated. The minimum thickness of 5.0 ft (Bureau of Land Management, 1986) and the maxi mum incremental stripping ratio of 4:1 criteria for beds below the Anderson or Canyon were selected on the basis of current mining practices in the Gillette coal field (Luppens and others, 2008). Subsequent to bed selection for the mining economic evaluation, a composite stripping-ratio map was generated and the recoverable coal resources for each strip ping increment from 1:1 to 10:1 were calculated. For the Gillette coal field assessment, the exception ally thick Anderson and Canyon bed sequence dominated the economic evaluation. These two coal beds are generally close to each other stratigraphically with little or no separa tion by parting material. The Roland and Smith coal beds stratigraphically above the Anderson and Canyon beds were also included in the Gillette coal field mine models. No coal beds below the Canyon bed were economically assessed. The Anderson and Canyon beds accounted for about 82 percent of the total recoverable coal resources in the Gillette coal field (Luppens and others, 2008). Additionally, this thick coal interval represented more than 90 percent of the resources to the 6:1-7:1 stripping-ratio interval. Use of the USGS CoalVal program (Rohrbacher and McIntosh, 2010), which aggregates all coal beds into a single composited bed mine model provided an appropriate regional mine model for the Gillette coal field. In the northern portion of the Gillette coal field, the Ander son and Canyon beds begin to separate and thin significantly to the north and northwest into the NWPRB assessment area con tinuing into the MTPRB assessment area. Similarly, the Canyon bed separates into the Canyon and Lower Canyon beds in these directions. Typically, mining costs are higher for the recovery of multiple beds as opposed to a single bed scenario, which was used in the Gillette coal field assessment. To address the mining conditions in the NWPRB and MTPRB assessment areas, a new surface mine model program was developed to evaluate multibed sequences, rather than the CoalVal program used for the Gillette coal field assessment (Scott and others, 2010). For the NWPRB assessment area, DCF mining costs were as much as $6/ton higher than the costs for the same stripping ratio incre ment for the Gillette coal field (Luppens and others, 2008). The same methodology to parse out coal resources by composite stripping ratio increments in the Gillette coal field assessment (Luppens and others, 2008) was used for the NWPRB assessment area. However, with more beds having thinner average thicknesses throughout a larger stratigraphic interval, the approach to the coal reserve evaluation model for the NWPRB assessment area had to be modified. The Roland (Baker), Smith, Anderson, Dietz 3, Canyon, Lower Canyon, and Werner beds were selected for the economic evaluation. However, not all beds are present everywhere in the NWPRB, further complicating the development of a regional mine model for this area. This is especially true for lower stripping ratios. For example, in the 2:1 ratio areas, some areas contain the Werner and Lower Canyon or Lower Canyon and Canyon, or other bed combinations. For strip ping ratios of 5:1 or greater, five or six of these assessed beds are typically present. Interburden thicknesses between the beds are also variable. Developing a single regional model with bed and interburden variability represented a challenge. A straightforward modeling approach was needed that still addressed the multibed situations in this area. The regional mine models for the Wyodak-Anderson coal zone for the NWPRB and MTPRB assessment areas were formulated on a representative model-bed section based on approximate average thicknesses for the coal beds and average interburden intervals assessed for reserves. An example of a regional mine model stratigraphic sequence used for the economic evaluation of the NWPRB assess ment area is shown in table 10. All strata in this model are assumed to be near horizontal. One coal bed is modeled at the 1:1 ratio, and additional coal beds are added from the 2:1 through 4:1 ratios. Because the coal beds in lower
Surface Coal Resource Assessment 31 ratio models are highly variable, the coal beds are labeled beds 1-4, rather than using specific bed names. For the 5:1 through 10:1 stripping ratios, six coal beds are modeled (table 10). To simplify the models, interburden thicknesses remain constant and overburden is increased for the 5:1-10:1 ratio models. Although the mine model used is a simplifica tion of the actual conditions, this approach still provided a more realistic representation than the single-bed model scenario used in the Gillette coal field assessment (Luppens and others, 2008). Active coal mining in Montana occurs in two strati graphic zones (Haacke and others, 2013). Coal mines near Decker, Montana, (figs. 2 and 12) are recovering coal from the upper Wyodak-Anderson coal zone (Anderson to the Dietz 3 beds) (fig. 13). For the MTPRB assessment area, a representative regional model was developed based on approximate average thicknesses of five coal beds (Roland (Baker), Smith, Anderson, Dietz 2, and Dietz 3) (Haacke and others, 2013). The first coal bed was modeled at the 1:1 strip ping ratio; additional coal beds were added for stripping ratios from 2:1 through 4:1. To simplify the models, interburden thicknesses remained relatively constant and overburden was increased for the 5:1-10:1 stripping ratio models. Currently, coal beds in the lower part of the WyodakAnderson coal zone are not mined in the MTPRB assessment area. However, there are areas where the Canyon and Werner/ Cook coal beds are relatively thick and occur at shallow depth with stripping ratios less than 10:1 (figs. 129 and 130). There fore, in addition to the regional mine model sequence, single bed mine models of the Canyon and Werner/Cook coal beds were evaluated for reserve potential. Active mining below the Wyodak-Anderson coal zone is unique to the MTPRB assessment area (Haacke and others, 2013). Several mines are recovering coal from the Rosebud/ Knobloch coal bed (fig. 13) near Colstrip, Montana (figs. 2 and 12). In addition to the Rosebud/Knobloch bed, the Pawnee and Flowers-Goodale coal beds locally contain thicker pods of coal below the Wyodak-Anderson coal zone at stripping ratios less than 10:1 (figs. 131-133). Therefore, single bed mine models of the Pawnee, Rosebud/Knobloch, and FlowersGoodale coal beds were also evaluated for reserve potential (Haacke and others, 2013). For the SWPRB assessment area, a number of adverse geological factors were encountered. The most important factor was the thinning and splitting of the deep WyodakAnderson coal zone towards the southern and western flanks of the PRB shown on figures 8 and 9. Relatively steep dips (10-25°) (Flores and others, 1999) of coal beds on the western flank of the PRB, such as in the Sussex coal field (fig. 6), are also a limiting factor. Thin coal beds combined with relatively steep dips severely limit the potential for mining (Osmonson and others, 2011). Coal quality is an additional adverse factor in the SWPRB assessment area. Associated with the thinning and splitting of the coal beds in this area is the presence of numerous thin, high-ash partings within individual coal beds. These part ings negatively affect coal quality by increasing ash content and lowering calorific values (Luppens, 2011). The potential for even lower grade coal quality was a factor in the deci sion to close the Dave Johnston Mine in 2000, the only large commercial mine developed in the SWPRB (fig. 12). Factors contributing to the mine closure were an increase in the strip ping ratio, coupled with inherent adverse geologic conditions and deteriorating coal quality (PACIFICORP, 2008). Clo sure of this mine reflects the trend of decreasing coal quality along the shallow southern and western flanks of the SWPRB assessment area. The lack of extensive, thick, shallow coal bed explora tion targets coupled with poor coal quality has resulted in a lack of sufficient drilling (both conventional coal exploration holes and coalbed methane) in this area. Additional drilling is necessary to adequately assess surface recoverable coal resources for the SWPRB assessment area on a regional basis. No economic analysis of surface recoverable Fort Union Formation coals-Roland (Baker) and Smith-was performed for the SWPRB assessment area. The Wasatch Formation in the SWPRB assessment area locally contains thick coal beds (fig. 23), but these typically have higher ash and sulfur contents and lower gross calorific values (table 2) (Luppens, 2011; Osmonson and others, 2011). The Lake DeSmet area in the SWPRB assessment area contains thick Wasatch Formation coals that have been commercially evaluated a number of times for potential min ing. Despite the fact that the Lake DeSmet coal zone in the Wyoming PRB is the thickest known coal zone in the con tiguous United States, no significant, large-scale mining has occurred in the Wasatch coal beds in the PRB. Luppens (2011) noted that published coal quality values for the Lake DeSmet area (Mapel and others, 1953) were overly optimistic as all partings greater than 3/8 inch were included from the core samples prior to analysis. Furthermore, at least one of the cores (Bureau of Reclamation core) from Mapel and others (1953), experienced unaccounted moisture loss, which resulted in anomalously high calorific values. The results from the USGS-1 core hole (Mapel and others, 1953) were evaluated to estimate the effects on reported coal analy ses using more likely moisture levels and with the estimated impacts of compositing the originally excluded shale, pyrite, and other high-ash parting material. The predicted moisture increased about 1.5 percent. More importantly, the predicted ash contents increased to a range of 12.9-15.6 percent with a corresponding decrease in calorific values with a range of 6,986-6,694 Btu/lb depending on volumetric or mass weight ing (table 11). The predicted quality is significantly lower than the original reported ash and calorific values of 5.0 percent and 7,970 Btu/lb, respectively (Luppens, 2011). It is suspected that the relatively inferior predicted coal quality may be a con tributing factor to the lack of development in the area.
32 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana A surface mining reserve analysis was not performed for the Upper Healy or the Healy coal beds due to a combination of negative factors within the Lake DeSmet area including unfavorable stripping ratios, restrictions to mining including extensive areas of clinker, and predicted inferior coal quality. Although limited areas of these beds could possibly be mined in the future, this scenario was not addressed because of the regional scope of this assessment and the lack of sufficient data necessary to outline specific small areas for potential surface mining (Osmonson and others, 2011). Regional Surface Mine Modeling Once a simplified geologically based mining sequence was developed for an assessment area, the USGS estimated potential recoverable coal resources and evaluated the cost of developing and operating a typical coal mine. For each of the four assess ment areas, a regional surface mine model was developed to calculate expected mining costs based on the bulk volume and mass excavation of overburden and coal, respectively. How ever, the Gillette coal field was an exception. Field mine plans from recently filed State mining permits and discussions with mine operators in the southern part of the coal field indicated that mining progress could be affected by the joint Burlington Northern Santa Fe and Union Pacific Railroad (Joint Line) (fig. 19) within 10-12 years (Luppens and others, 2008). In 2006, two coal lease-by-applications (West Jacobs Ranch and West Hilight Field) confirmed that coal mining companies were planning to develop new mining pits west of the Joint Line (fig. 19) (Bureau of Land Management, 2013). Mining west of the railroad would require a deep box cut to extract the coal resources. The expense of this box cut would significantly affect the cost of mining west of the railroad, which would require a separate mine plan. Additionally, leaving the Joint Line intact produced two new restrictions to mining. One restriction accounted for the amount of coal resources affected beneath the Joint Line right-of-way, and the second estimated the amount of coal resources affected by the box cut development west of the Joint Line for overburden storage and mine facilities. USGS regional modeling is different from evaluation of specific mining properties. With a single basinwide approach, some generalizations must be made. Certainly, customizing mine plans for each unique property within an assessment area would be better, but prohibitive in terms of time and manpower requirements. The regional mine models are used to produce a prefeasibility or conceptual level evaluation to determine which portion of the recoverable coal resources (reserves) could be economically extracted at the time of the determination. A conceptual economic study should have error limits of 30 to 50 percent (Rupprecht, 2004). The USGS assessment methodology is also consistent with EIA DRB criteria. Some USGS coal availability studies have already been used to update the EIA Agency coal resource and reserve data (U.S. EIA Agency, 1997). The regional mine model developed for the Gillette coal field is a set of 10 mine models, one for each stripping ratio from 1:1 to 10:1. The 10:1 ratio was chosen based on geolog ical constraints. The 10:1 stripping ratio limit in the Gillette coal field approximately coincides with a north-southtrending distributary channel against which the Anderson and Canyon coal beds thin and pinch out. This channel effectively poses a down dip barrier to surface mining in the Gillette coal field (Luppens and others, 2008). The USGS CoalVal program (Rohrbacher and McIntosh, 2010) was used to evaluate the regional mine model for the Gillette coal field assessment. This program combined total coal bed and burden thicknesses. To better address the thinner coal beds and larger interburden intervals for the NWPRB and MTPRB assessment areas, multibed regional mine models were created by USGS personnel using Microsoft EXCEL (2007) spreadsheets. Both mining programs were used to calculate recover able coal resources and capital and operating costs on a DCF basis. The DCF cost to produce a ton of coal is applied to all available coal resources within each stripping ratio incre ment of the ratio model. The breakeven cost is compared to the current (December 2013) sales price of coal on a per ton basis. The coal is economically minable when the DCF is less than the sales price and is uneconomical when the DCF cost is greater than the sales price. Surface Mine Model Design Assumptions Oral communication with existing PRB coal mining companies was valuable to the development of the regional mine models. Although many PRB mines have been in operation for 30 years or more, a 20-year economic life was used for all assessment models. Production rates were chosen for each assessment area based on a reasonable tonnage rate between the minimum and maximum yearly production rates for several mines within an assessment area. For the Gillette coal field, a production rate of 35 million short tons per year (MST/yr) for the regional mine model was used. A nominal production rate of 10 MST/yr was selected from numerous mine models as being most representative for mining cases for the NWPRB and MTPRB assessment areas. Overburden removal for the Gillette coal field con sisted of a large dragline used together with truck-shovel pre-stripping. This cost effective overburden removal system takes advantage of dragline efficiencies and the flexibility of the truck-shovel operation to strategically place the spoils near final reclamation grade. The dragline operation uses cast-blasting to move a portion of the overburden into its final location across the open pit rather than using mining equipment. Cast-blasting is more cost effective than moving the same volumes by dragline or dozers. The dragline and asso ciated stripping dozer operation is scheduled to remove 140 ft of overburden directly above the Anderson coal bed. This schedule allows the dragline and its associated equipment and manning requirements to remain constant from model to model. As the stripping ratio increases, more equipment and
Surface Coal Resource Assessment 33 manning requirements were added to the model. The mine models were designed to assume that new, optimally-sized equipment would be purchased and operated on a 24-hoursper-day, 7-days-per-week schedule. Except for the dragline, 10 holidays were scheduled for all equipment operations. The amount of stripping equipment and coal production equipment was determined from truck-haulage simulations, shovel productivities, and reported dragline productivities at existing mines in the Gillette coal field (oral communication with various mine managers). For the southern one-half of the Gillette coal field, where the Joint Line Railroad is located on available coal resources, a new box cut would be required to access the coal west of the railroad (fig. 19). This box cut is a challenge both economically and logistically (Luppens and others, 2008). The projected time required to open a box cut using truck shovel equipment could vary from more than one year for a 3:1 ratio box cut, to nearly three years for a box cut at a 9:1 ratio (Luppens and others, 2008). Such operations would require additional equipment separate from the mining operations east of the Joint Line, which exacerbates the financial effects of the new box cut. During development of the new box cut, coal production would continue in the pits east of the Joint Line, as no coal would be produced during the new box cut construction. The long lead times necessary for box cut development presents a major tim ing challenge. Production in the new box cut west of the Joint Line must be ready to start as production east of the of the Joint Line finishes. When the dragline overburden removal operations east of the Joint Line are finished, the equipment would have to be moved across the railroad to begin overburden removal in the next cut. Back-filling the eastern pit with spoil from the box cut pit would not be possible, leaving an out-of-pit overburden dump immediately west of the Joint Line as the only feasible option for the box cut spoil. Conventional truck-shovel operations were used for the NWPRB and MTPRB assessment area models, which facili tated more complex, multibed mining scenarios. The multibed model considered each bed in the stratigraphic sequence as a separate mining operation with the uppermost bed recovered before the next lower bed. A load-out capacity was calculated for each mining pass or bench. Equipment for overburden and interburden stripping and coal loading and hauling was sized for a 10 MST/yr mining operation. Shovel loading and rear dump-truck haulage were used to provide a common basis for the comparative modeling results produced in this assess ment. Stripping shovels were sized for operating at 89 percent availability and 95 percent utilization for 6,300 hours per year. Coal-loading shovels were sized for operating at 89 percent availability and 85 percent utilization for 5,633 hours per year. These efficiencies allowed the calculated stripping volume to remain in advance of coal loading. Both operations were con ducted on a two shift per day, 350-days-per-year basis. Strip ping and coal-loading shovels have a range of 15-60 cubic yards in bucket capacity. Mining support equipment costs were included for haul-road maintenance, night illumination, in-pit water handling, and transportation. In addition to the multibed model for the MTPRB assess ment, single bed mine models were evaluated for five coal beds below the Dietz beds, including the Canyon, Werner/ Cook, Pawnee, Rosebud/Knobloch, and Flowers-Goodale coal beds. The same surface mining assumptions and parameters used for both the multibed and single-bed models. The singlebed models were comparatively simple as the logistics for the overburden stripping operations for multiple beds are more complex. All coal beds in the Gillette coal field are blasted before loading. In the NWPRB and MTPRB assessment areas coal beds are ripped and heaped before loading. The mine models include initial capital, replacement capital, and operating costs for each major operational activity. Operational activities included overburden and interburden removal, coal loading and hauling, reclamation, general mine equipment application, and facilities use. Equipment and staffing costs and produc tivities were obtained from a variety of sources including the Society of Mining Engineers of The American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. (1973), Caterpillar, Inc. (2012), InfoMine USA, Inc. (2010), and discussions with coal companies (oral commun., 2006, with various PRB coal companies). Surface Mine Plant Facilities The mine plant contains those facilities essential for sup porting mining. The mine plant facilities include an adminis tration building, change house, maintenance shop, warehouse, laboratory building, emergency building, utility building, and guard house. This assessment includes several mining scenarios (stripping ratios of 1:1-10:1) for which different plant space requirements are anticipated, and the buildings were sized accordingly. Coal handling at the mine plant includes truck scales, inclined and horizontal belt conveyors, stacking tubes, scalping screen, coal breaker, coal silo, belt sampler, belt scales, rail loop or spur, railcar mover, and associated equip ment. The mine plant also includes multiple elevated steel structures, enclosures, and concrete foundations. Preliminary designs for a truck dump to accommodate a wide range of large rear-dump truck capacities and a railroad loop were developed, from which unit costing was performed. The cost of a typical mine plant for the mining models were calculated for all case studies, which included costs for the following items: land improvements buildings coal handling equipment and structures truck dump railroad loop and access miscellaneous structures mobile and stationary equipment
34 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Surface Mine Reclamation Reclamation is an additional ongoing function and significant cost factor in the surface mine model. A fleet of earthmoving and farm-type equipment perform a variety of activities from removal of vegetation and topsoil through contouring spoil piles, seedbed preparation, and planting. Scrapers remove and transport top soil to temporary storage piles and later transport top soil to contoured spoil piles for covering. Bulldozers remove brush, trees, and other debris during land clearing, rip topsoil, and assist scraper load ing. Motor graders contour and scarify bare spoil piles for revegetation. Farm tractors with disc and seeder apparatus reestablish vegetation and mulch blowers are used to cover spoil piles. Surface Mine Supplies and Utilities Additional costing items in the surface mine model include equipment operating items, personnel wages, explo sives, mulch, and seed. Utilities include electricity and natural gas/propane. Surface Mine Reserve and Recoverable Resource Evaluation Results All current mining operations in the Wyoming PRB recover coal from beds in the Wyodak-Anderson coal zone of the Fort Union Formation. The Wyodak-Anderson coal zone represents about one-half of the total remaining available coal resources in the PRB (fig. 118). The coal beds within this zone dominate the recoverable resource analyses. All coal beds in the Wyoming assessment areas that have been economically evaluated were within the Wyodak-Anderson coal zone. Sev eral beds below the Wyodak-Anderson zone were evaluated in the Montana PRB. Some additional data entry, coal bed correlation work, and consolidation of local bed names were completed for this final PRB assessment report. This work was essentially limited to beds stratigraphically below the Wyodak-Anderson coal zone in the three Wyoming PRB assessment areas and were not included in the reserve analyses for the four regional assess ment reports. No significant recoverable coal resources were found in the East Gillette extension area, which was completed following the four PRB regional assessments. Therefore, revised reserves analyses for this report were not necessary. Determination of Reserves Once the available coal resources were allocated and economic mine models completed for an assessment area for each stripping ratio mine model (1:1-10:1), reserves were estimated from a portion of the total in-place (remaining) coal resources. The term "reserves" relates to that portion of demonstrated resources that can be recovered economi cally with the application of extraction technology available currently or in the foreseeable future (EIA Agency, 1997). Furthermore, the term "reserves" need not signify that extraction facilities are in place or operative (Woods and others, 1983). To derive a reserve estimate for each assessment area, a composite cost curve was developed for the total recover able coal resources by incremental DCF costs. Cost curves provide a straightforward method of relating recoverable tons of coal to current (December 2013) sales prices (for example, see figure 123). All of the recoverable tons of coal to a 10:1 stripping ratio in a given area are sorted from lowest to highest DCF costs per ton and plotted against DCF cost. If the current (December 2013) market price for coal is $12.00/ton (fig. 123), 30 BST tons by definition would be considered reserves (potentially produced at or below market price). Because a coal reserve estimate is based on a single reference point in time, the use of cost curves is particularly useful given typical fluctuations in the market price. From the cost curve, the rela tion between changes in the sales price and estimated reserves can readily be demonstrated. If the market price increases to $18.00/ton, the estimated reserves would double to 60 BST, assuming mining costs were similar. Because reserves refer to that portion of the recover able coal resource that can be mined at a profit at the time of the assessment, it was necessary to determine the current (December 2013) FOB market price. The sale of coal is normally based on heating value (Btu/lb, as-received basis); therefore, the average regional coal heating value for each PRB assessment area was required. On the basis of pub licly available data, an average heating value (Btu/lb) was derived. Average coal quality was used because the lack of specific data for every coal bed precluded development of more precise coal quality models. For the Gillette coal field and MTPRB assessments, an average heating value of 8,800 Btu/lb was used; an 8,400 Btu/lb average was used for the NWPRB assessment area. The following sections provide a synopsis of the eco nomic analyses for three of the four assessment reports and a summary of reserves and total recoverable coal resources for the entire PRB (table 11). As previously discussed, no economic analysis was conducted for the SWPRB assess ment area because of a combination of negative factors. The individual PRB coal assessment reports (Luppens and others, 2008; Scott and others, 2010; Haacke and others, 2013) can be reviewed for more detailed information. The DCF costs used a common 8 percent rate of return (ROR) for all assess ment areas. Gillette Coal Field Assessment Area Six coal beds selected for the economic analyses in the Gillette coal field are listed in table 12. Four of these are of minor importance (Roland [Baker], Smith, Anderson Upper Rider, and Dietz 3). The total recoverable coal resources are dominated by the thick Anderson and Canyon bed sequence, which represents 83 percent of the total recoverable coal resources in the Gillette coal field (Luppens and others, 2008).
Surface Coal Resource Assessment 35 The combination of extensive, thick, coal beds at shallow depth, with low-ash and low-sulfur content, makes the Gillette coal field the most important coal field in the United States. All current coal production in the Gillette coal field is from the Anderson and Canyon coal beds along the eastern margin of the basin. As mining continues down dip from the east margin, progressively younger beds (Smith and Roland [Baker]) that lie above the primary Anderson-Canyon target beds would be exploited (fig. 10). The combination of exten sive, thick, coal beds and relatively moderate topography resulted in broad areas in the Gillette coal field with stripping ratios of 10:1 or less (fig. 124) (Luppens and others, 2008). With a January 2007 sales price of $10.47 per ton for the 8,800 Btu/lb coal from the Gillette coal field for the Anderson and Canyon beds (Platts, 2007), an estimated 10.1 BST of the total 77 BST of recoverable coal resources are considered coal reserves (fig. 125). As of March 2008, the sales price for the Gillette coal field had increased to $14.00 per ton (Platts, 2008). Assuming that operating costs remained essentially unchanged during the 15-month period since the reserve study was completed there would be approximately 18.5 BST of reserves (fig. 125). Thus, an increase in the sales price of only approximately $3.50/ton nearly doubled the reserves estimate. Northern Wyoming PRB Assessment Area Northward from the Gillette coal field, the coal beds split and thin presenting a different mining scenario. The Roland (Baker) and six beds from the Wyodak Anderson coal zone (table 12) were selected for the economic evaluation (Scott and others, 2010). There are two regions of shallow coal with cumulative stripping ratios of 10:1 or less (fig. 126). The more extensive of the two areas is found on the eastern side of the NWPRB assessment area where the regional dip is relatively low (fig. 9). The area of 10:1 ratios or less north of Sheridan, Wyoming, is much more restricted areally because of steeper dips on the west side of the basin. The most noteworthy aspect of figure 126 is the limited extent of areas less than a 5:1 stripping ratio, where resources considered reserves would be found. Although mining has occurred in the NWPRB assessment area, there are no active mining operations in this assessment area. With a January 2010 sales price of $9.30 per ton for the 8,400 Btu/lb coal from the PRB (Platts, 2010), an estimated 1.5 BST of the total 50 BST of recoverable coal resources are considered as coal reserves (table 12). The relatively low reserve estimate is directly related to the limited areal extent of resources found at less than a 5:1 stripping ratio (fig. 126). The mining costs for the NWPRB assessment area are higher than those for the Gillette coal field assessment (Scott and others, 2010) because of the more complex coal geology and multibed mine models that are inherently more costly than the simpler single-bed model used for the Gillette assessment. Also, the mine model for the NWPRB assessment area used truck-shovel operations exclusively for more coal beds with thicker interburden intervals. For the Gillette coal field, a dragline operation combine with truck-shovel operations for prestripping was used to take advantage of the lower unit strip ping costs that a dragline offers. The cost curve (fig. 127) readily demonstrates the relation between sales price and estimated reserves. On January 5, 2009, the sales price per ton for the 8,400 Btu/lb coal from the PRB was $11.00 per ton (Platts, 2009a). An estimated 3 BST would be a reserves equivalent at this price. The $11.00 per ton price held steady through April 6, 2009, then suddenly dropped to $8.00 per ton in one week (Platts, 2009b, c). By November 23, 2009, the sales price had bot tomed out at $7.65 per ton (Platts, 2009d), which would be a reserves equivalent of 0.8 BST at this price. The sales price as of January 2010, for 8,400 Btu/lb coal from the PRB was $9.30 per ton (Platts, 2010) (fig. 127). The changes in the sale price during the 10-month period corresponded to a 1.9 BST swing in reserves estimates from a maximum of 3 BST to a low of 0.8 BST, emphasizing the value of preparing cost curves. Montana PRB Assessment Area The coal geology in the Montana PRB differs from the Wyoming PRB. The coal bed thicknesses in the MTPRB assessment area are more variable than in the NWPRB assess ment area of Wyoming (Scott and others, 2010). Areas of thicker coal (greater than 20 ft thick) are more pod-like as illustrated by the isopach maps of the Dietz 3, Canyon, Lower Canyon, Werner/Cook, Pawnee, and Flowers-Goodale coal beds (figs. 62, 68, 69, 76, 84, and 104). Deeply-dissected drainages limit the areal extent of shallow, surface-minable coal beds in the MTPRB assessment area. Figure 10 illustrates the more deeply incised topography in Montana. The MTPRB assessment area is the only area in the PRB that contains potentially minable coal beds, below the Wyodak-Anderson coal zone (fig. 13) (Pawnee, Rosebud/Knobloch, and FlowersGoodale beds), that are both sufficiently thick and have a significant areal extent at stripping ratios at or less than 10:1 (figs. 128-133). Ten of the 18 coal beds had sufficient areal extent and thickness to be further evaluated for recoverable coal resources (Haacke and others, 2013). Five of these beds, the Roland (Baker), Smith, Anderson, Dietz 2, and Dietz 3 were combined into a regional, multibed mine model. Por tions of this sequence are currently being mined at the Decker and Spring Creek Mines in the southwestern portion of the MTPRB assessment area (fig. 12). The stripping ratio map for this mine model sequence is shown in figure 128. In addition to the regional mine model sequence, the Canyon, Werner/Cook, Pawnee, Rosebud/Knobloch, and Flowers-Goodale coal beds were evaluated for reserve poten tial (table 12). Of these five beds, only the Rosebud/Knobloch bed is currently being mined in the Colstrip area (figs. 1 and 12). Additionally, the Rosebud/Knobloch bed is the primary target in the Otter Creek lease area (fig. 12). The stripping ratio maps for these coal beds are shown in figures 128-133.
36 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana The individual coal bed stripping ratio maps demonstrate the relation between the deeply-dissected surface morphology and coal thickness. A comparison of the isopach map and stripping ratio map for a given bed illustrates this relation. For example, the more extensive area of less than a 10:1 ratio in R. 39 E. to R. 41 E. for the Werner/Cook bed (fig. 130) corresponds to the thickest portion of the Werner/Cook bed (fig. 76). Elsewhere, the less than 10:1 ratio areas for the thinner por tions of the Werner/Cook bed are confined to narrow bands along drainages. A total of 39 BST, at a stripping ratio of 10:1 or less, remains in the 10 beds assessed for reserves. After mining and processing losses were subtracted, about 35 BST of coal were considered recoverable coal resources (table 12). To derive a reserve estimate for the MTPRB assessment area, a composite cost curve was developed for the cumulative total 35 BST of recoverable coal resources using the November 2011 FOB sales price for 8,800 Btu/lb coal from the PRB of $13.20 per ton (Platts, 2011a). The reserve estimate for the MTPRB was about 13 BST (table 12, fig. 134). Combined PRB Reserve and Recoverable Resource Summary Resources and reserves of the Gillette coal field, NWPRB, SWPRB, and MTPRB assessment area as well as total PRB resources and reserves are summarized graphi cally (fig. 135). The total coal reserves estimate for the PRB is 24.5 BST from the three areas assessed for surface min able coal. The most striking feature of these bar graphs is that the reserves are a small fraction (about 2.3 percent) of the total, original in-place resources. A significant amount of coal affected by all restrictions to mining (coal too thin, depth, towns, and other restrictions) and mining losses precludes recovery of most of the original in-place coal resources. The relation of original resources to reserves is consistent with previous USGS coal assessments, which typically determine the reserve fraction to be less than 20 percent (Luppens and others, 2009). The value of economic-based assessments is to provide resource planners with realistic estimates of resources that are recoverable and an understanding of the importance of differentiating between in-place resources and reserves. The PRB assessments were completed sequentially and consequently market prices were different at the time the cost curve for each study was generated. To simplify the process of generating a single, unified reserve estimate for the entire PRB, all recoverable coal resources needed to be evaluated on a common market sales price basis. The DCF costs for all the individual stripping ratio mine models from the Gillette coal field, NWPRB assessment area, and MTPRB assessment areas were combined into a single cost curve. The result of the aggregation of mine model costs is the cost curve shown in figure 136. Using the FOB sales price of $10.90 per ton as of July 15, 2013 for PRB 8,800 Btu/lb coal (Platts, 2013), the coal reserve estimate for the entire PRB is about 23 BST (fig. 136). This is slightly lower than the simple addition of the reserve estimates from the Gillette coal field, NWPRB assessment area, and MTPRB assessment area reports because of a small decrease in market price in June 2013. This difference in reserve estimate underscores the fact that reserve estimates are a constantly moving target, as sales prices continually fluctuate, responding to variations in market demand. For example, in November 2009, the sales price for PRB 8,800 Btu/lb coal had dropped to $8.90 per ton (Platts, 2009c), and subsequently increased to $15.15 per ton in December 2011 (Platts, 2011b). The effect of this market price variation on the range of reserve estimates was a low of 10 BST to a maximum of 43 BST (fig. 136). The use of cost curves provides flexibility to adjust the reserves estimates to fluctuations in market price. Single estimate results are essen tially frozen in time based on the economic conditions at the time of the assessment. While the estimates of reserves are important, the relation between reserves and recoverable coal resources is equally significant, especially in light of the fundamental mission of the USGS Coal Assessment Project which is to determine the coal reserve base in all major U.S. coal basins. The coal reserve base includes identified resources that meet specified minimum criteria related to current mining and production practices, including those for quality, depth, thickness, and rank (Woods and others, 1983). These recoverable coal resources are essentially equiva lent to coal resource categories included in the EIA-estimated recoverable reserves (ERR) database (Energy Information Administration, 1997). The ERR, which is updated by the EIA periodically, is currently the only published national summary of potentially recoverable coal in the United States. The ERR is the portion of the DRB coal that may be recoverable, based on regional estimates of coal resource accessibility and mining recovery rates. It is especially important to understand that the coal reserve base may encompass those parts of a resource that have a reasonable potential for becoming economically recoverable within planning horizons that extend beyond those which assume proven technology and current economics (Energy Information Administration, 1997). The ERR includes those resources that currently are classified as reserves and recoverable coal resources that may be mined in the future. It is a common misconception that any given estimate of reserves implies that the volume of coal in the reserves category is all that is left to recover. From figure 136, it can be seen that as market prices increase, the reserve estimate increases while the amount of remaining currently uneco nomic recoverable coal resources decreases and vice versa. Reserve estimates are by nature a moving target. Typically, as mining progresses in a basin, resources become progressively more expensive to produce. Sale prices generally increase as long as demand supports higher prices. With continued favorable sales prices and increased productiv ity and advances in mining technology that positively affect economics, resources once considered to be subeconomic may be elevated to the reserve status. For example, typical average stripping ratios in the Gillette coal field in 1990 were about 2:1 or less; therefore, resources greater than a 2:1 ratio would have
Underground Coal Resource Assessment 37 been placed in the recoverable coal resources category. PRB coal reserves currently mined include coal resources up to ratios ranging from 3:1 to 4:1 Reserve studies should be considered a cyclic process and models should be adjusted periodically using the most recent data and reassessed using the most current recovery technology and economics. Underground Coal Resource Assessment A significant volume of coal resources in the PRB are con tained in relatively thick coal beds at depths that may be imprac tical for surface mining. While no coal in the PRB is currently recovered by underground mining methods, nor expected to be in the near future, significant resources at depths of 2,000 ft or less are easily within the range of current underground min ing technology. An evaluation of potential underground coal resources was also conducted to determine a preliminary esti mate of the magnitude of underground resources. There are precedents for transitioning from surface to underground mining operations. Several other surface coal mines in western United States basins have converted to under ground longwall systems as surface coal reserves were depleted. For example, the San Juan operation near Farmington, New Mexico, consists of an underground mine accessed via the high wall of a closed strip mine (Mercier, 2010). The underground longwall operation has successfully extended coal extraction in a location where increasing overburden created unfavor able economics for further surface operations (Mercier, 2010). A similar situation developed at the Jim Bridger Mine near Rock Springs, Wyoming (PACIFICORP, 2011). The life of the mine was extended by developing an underground mine as surface minable reserves were nearing depletion to continue to provide fuel to the power plant for an additional 20 years (PACIFICORP, 2011). Underground longwall mining methods are used in a coal bed that has as much as 1,000 ft of overburden (PACIFICORP, 2011). The assessment of underground resources consisted of two parts. First, a mining method was selected and then a mine model was selected to generate estimated DCF cost per ton. This cost could then be compared to the cost of surface mining. The amount of deep coal in the PRB that was amenable to development by the selected mining system was inventoried. Two principal underground mining systems are used in the United States: continuous mining (commonly referred to as room and pillar) and longwall mining. The longwall min ing system was chosen as the preferred method for several reasons. Although a longwall system requires higher capital and installation costs, it has higher productivity and recovery rate than the continuous mining system. Additionally, the longwall system offers safety improvements, and offers the best opportunity for automation (U.S. EIA Agency, 1995). The minable coal bed thickness for longwall systems ranges from 5 to 13 ft (Thomas, 2002). Although longwall shearers are commonly used for bed thicknesses between 5 and 20 ft (Myszkowski and Paschedag, 2009), a 10-ft mini mum was used as a more conservative estimate of potential underground resources for longwall operations. For portions of coal beds that exceeded 20 ft in thickness, only a 20-ft slice of those beds was included to the underground resources estimate. All of the coal beds greater than 20 ft were consid ered unrecoverable by current underground technology. As with other coal basins, only a fraction of the total underground resource is typically recoverable. Factors such as adverse roof, floor conditions, slope of the coal beds, and essential safety barriers are restrictions to mining. Although recovery in multiple bed areas is generally most efficient by mining from the uppermost bed downward, that situation is impossible to control. Interburden between beds must be thick enough to prevent interbed structural problems. Underground Mine Model Design A preliminary underground mine model provides a reasonable estimate of the economic tipping point where underground mining might be a more viable alternative to surface mining, which establishes a limit on recoverable coal resources by surface mining. No underground mines are cur rently operating in the PRB as discussed in the NWPRB (Scott and others, 2010), SWPRB (Osmonson and others, 2011), and MTPRB assessment areas (Haacke and others, 2013). For each of these assessments, a separate underground mine model was developed. The NWPRB assessment area model was based on a production rate of 11 MST/yr and the SWPRB assessment area model was based on a production rate of 6 MST/yr. The SWPRB assessment expanded the scope of both the NWPRB and the MTPRB assessments, by considering the effects of coal thickness and depth. Potential underground coal reserves in the PRB assess ment area were evaluated using a conventional, single-pass, continuous, longwall mining methodology. Current face shearer and roof support design are available for mining up to 20 ft thick (Myszkowski and Paschedag, 2009), which is a reasonable thickness in portions of the PRB. With the excep tion of the Gillette coal field, underground mine models were developed for all the PRB assessment areas to estimate poten tial deep, recoverable coal resources. To provide an example of the level of detail in the conceptual underground mine model, the following sections describe the underground mine design used for the MTPRB assessment area. Underground Mine Layout Design The underground mine model incorporates longwall technology, which includes four primary components: (1) sur face mine plant; (2) underground mine plant; (3) development excavation; and (4) longwall panel. All openings, support pillars, and longwall panel dimensions were sized to provide an annual production of 6 MST/yr which is an average size for currently operating longwall mines (Paul Pierce, oral commun., 2013). This average annual production is acquired
38 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana through development, production, and pillar recovery opera tions. The model can be used to evaluate mining thicknesses that vary from 8 to 20 ft and depths from less than 500 to 3,000 ft. The model can also be used to evaluate a wide range of annual production rates with some adjustment to longwall panel access openings and pillar sizes. The mine model was designed for primary entry to the longwall panel through five parallel main drifts. Additional excavation included a three-entry headgate for incoming airway and main access to longwall mining and two entry tailgates for return airway and supplies. Both the headgate and tailgate open ings extend perpendicular from the main entries to the full panel length and are separated by the width of the longwall panel. An initial longwall face opening is excavated at the far end of the longwall panel that connects the headgate and tailgate. Annual production for the underground mine model is the sum of coal mined from main access, headgate, and tailgate excavation, longwall production, and pillar recovery. Physical dimensions of the longwall panel and associated mine open ings are adjusted to maintain 6 MST/yr of production. The effects of increased mining height and depth have been cor related with variable panel barrier-pillar size and overall pillar recovery. The longwall panel width varies only with mining height and the panel length and is adjusted to provide the over all annual production from entries, panel, and pillars. Surface Mine Plant Coal handling facilities are the primary purpose of the surface mine plant. The surface mine plant for the under ground mine are those facilities essential for supporting mining, including buildings, coal handling equipment, rail loading facilities, and mobile and stationary equipment. The mine model surface plant includes an administration building, change house, maintenance shop, warehouse, laboratory build ing, emergency building, utility building, guard house and tool sheds, and hoisting and ventilation facilities to support underground operations. Other facilities include a stacking tube, horizontal and inclined belt conveyors, scalping screens, coal breaker, coal silo, waste bin, rail loadout structure, rail loop, various elevated steel structures and housings, preparation plant, and concrete foundations. The inclined belt conveyor is included with the surface mine plant and the excavation for the incline is included with the underground mine plant. The use of a tan dem ramp and shaft arrangement is assumed for medium mine depths. Shallow underground mines will likely use ramps and deep mines will use shafts. All stationary coal handling facili ties have been oversized to move in excess of the 6 MST/yr production rate. Hoisting facilities are included in the surface mine plant and shaft excavation and furnishing are included in the underground mine plant component of the mine model. One dedicated ventilation shaft is included in the mine plant, but hoisting facilities have not been provided. Ventilation facili ties include two 10-ft-diameter 800-horsepower surface mine fans, ducting, concrete foundation, electrical controls and switchgear, and appropriate enclosures. Ventilation facili ties are constructed adjacent to a dedicated shaft for primary incoming airflow. Underground Mine Plant Three excavations (men-and-materials shaft, ventilation shaft, and ramp) connect surface and underground mine plants. A nominal depth of 1,000 ft has been used for shafts and an inclined length of 2,280 ft for a ramp. Both shafts have been excavated with large-diameter drilling equipment and lined with concrete. The ramp is excavated with a continuous mining machine and lined with rock bolts, wire mesh, and shotcrete. Primary excavations at the bottom of the underground mine plant at the men-and-materials shaft include a ware house, shop, lunchroom, refuge chambers, water sump, electrical substation, and connecting runaround access way. The bottom of the ramp is located some distance away and has excavations for refuge chambers, electrical substation, and runabout access way. Both the shaft and ramp stations are lighted. Stationary equipment in the shaft station includes air compressors and centrifugal water pumps. Both the shaft and ramp stations include concrete flooring, steel equipment bases, and electrical cable distribution. Fresh air provided by surface fans supplies the secondary air distribution using rigid ventilation ducts, which are boosted with auxiliary ventilation fans. This secondary system is used throughout the underground mine. Underground Mine Development Excavation Underground excavation that extends some distance beyond the shaft and ramp stations occurs prior to production mining as described for the production unit section of this assessment and is performed as a construction activity. Coal removed during this project phase is transported to the surface and disposed as a waste product. Development excavation includes five parallel headings with connecting crosscut openings. These headings extend to the edge of the mine plant barrier pillar. This barrier pillar is sufficiently sized for underground mine plant facilities protec tion from structural instability because of mining production. All excavation during this phase is performed by a continuous miner and supporting mobile equipment. Longwall Nanel and Nillar Pecovery The production unit is generally centered near the long wall panel. All pre-longwall mining following development excavation is considered production and transported offsite for sale. The production unit includes the main access way extending from the initial development excavation, gateway excavation, longwall opening, and longwall panel. Gateway excavation starts at the main access way and extends to the full length of the longwall panel. A three-entry arrangement is developed for the headgate and two entries for the tailgate. A single longwall opening is excavated to connect the ends of the gateways. A longwall panel that is 1,000-ft
Conclusions 39 wide is included in the underground mine model design. This panel size is estimated to provide sufficient coal for a con tinuous year of operation without moving to a new area. A complete suite of standard equipment is included in the model (face shearer, roof supports, armored face conveyor, and sup porting systems). Pillar recovery provides substantial coal production as a final activity in the typical production unit. This operation involves trimming single pillars to an extent that coal can be produced without collapsing the immediate roof area during the activity. Pillar recovery is included in the underground coal mine model for chain pillars, panel barrier, and main access pillars for the typical longwall unit. High vertical stresses are applied to the lateral edges of the longwall panel as the shearer cuts across the face of the long wall and progresses toward the end of the panel. These stresses tend to concentrate over the rib line of the opening adjacent to the panel. The forward edge of the first row of support pillars in the gateways on either side of the panel, are expected to partially collapse. This collapse is likely to cause a yield zone that extends some distance into the pillar interior. The remaining portion of the pillar is expected to be competent enough to allow significant recovery by a continuous miner. The vertical stress concentration over the outer pillar line in the headgate should be less than the stress over the longwall panel periphery, and a higher pillar extraction rate can be expected. All the coal on the panel side of the barrier pillar is expected to be unrecoverable. Pillar recovery will need to be conducted from the main access way. Excavation of the barrier pillar will be conducted in concert with main access-way pillar recovery. Only partial recovery will occur to leave sufficient natural support for retreating from the area. Underground Coal Resources Results Eleven coal beds within the PRB were assessed as poten tially minable by underground operations. These coal beds, which have favorable thicknesses, depths, and areal extents for possible underground extraction in the future are the Roland (Baker), Smith, Anderson, Dietz 3, Canyon, Lower Canyon, Werner, Otter, Pawnee, Rosebud/Knobloch, and FlowersGoodale. Total resources in beds between 10 and 20 ft in thickness and 500 ft or greater in depth are about 304 BST (table 13). About 99 percent of the resources assessed were less than 2,000 ft in depth. Almost one-half (48 percent) of those deep resources are found in just two of the coal beds (Smith and Canyon) (table 13). Two-thirds of the deep resources are found within the SWPRB assessment area. This is not surprising given the extraordinary thickness of the Smith and Canyon beds in the deeper portions of the PRB. Because of slightly different geological conditions and mining assumptions used in the three assessment areas evalu ated for underground resources, the breakeven cost per ton ranged from $20 per short ton to about $31 short ton (Scott and others, 2010; Osmonson and others, 2011; and Haacke and others, 2013). Given the current sales price of about $11 per short ton for 8,800 BTU/lb for PRB coal (Platts, 2013); the estimated cost of underground mining is about 2-3 times the current (December 2013) FOB sales price. Therefore, none of the coal resources in the 11 deep coal beds in the PRB can currently be classified as reserves. A factor that will improve underground coal mining economics is that the heating value of coal increases with depth. The estimated calorific values of the deep coals range from about 9,300 Btu/lb at 1,000 ft depth to 10,000 Btu/lb at 2,000 ft depth (Luppens, 2011; Osmonson and others, 2011). The higher cost of underground mining might be partially offset by progressively higher quality coal with depth. Various restrictions, such as the geotechnical constraints of adverse roof and floor conditions, local coal bed thinning, and hydrology issues, would reduce the amount of coal resources ultimately recovered. The deep, thick coal beds in the PRB represent a significant future, long-term resource. The longwall model analyses demonstrate that as the surface mining depths continue to increase in other parts of the PRB, underground exploitation of deep, thick coal, in the SWPRB assessment area may become an increasingly viable alternative as long as the demand for coal supports higher prices. Conclusions This report presents the final results of an 8-year effort to collect sufficient data to map and model 47 significant coal beds individually for the entire PRB. Previous resource assessments in the PRB have relied on net coal isopach maps, which provide reasonable estimates of in-place resources, but are insufficient for conducting economic analyses to derive reserve estimates and the total amount of recoverable coal. The tremendous amount of CBM development in the PRB during the last 10 years has provided a wealth of new, publicly available data, especially in the Gillette coal field. Because the PRB is the single most important coal basin in the United States in terms of yearly coal production, incorporating as much of these data as practical was warranted. Some of the key results of this assessment are: The total number of holes in the final PRB database increased to 29,928, about 13,700 holes entered and interpreted by USGS personnel. In the Gillette coal field alone, the original database was expanded from about 2,391 to 10,210 data points. Additional data and support were provided by the Wyoming State Geological Survey and the Montana Bureau of Mines and Geology. The increased data control significantly improved the geological interpretation, including revision of coal bed correlations and increased geological assurance for the resource and reserve estimates. This report is groundbreaking as it provides the first published maps of the individual coal beds for the entire PRB. Unification of local bed names was crucial to this achievement.
40 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana The new geologic coal bed models provide a more robust assessment of recoverable coal resources and also facilitate other resource planning, such as develop ing CBM and evaluating the environmental effects of energy-related production. The methodology for assessing the restrictions to mining was improved from the previous "cookie cut ter" approach to allow for safety setbacks needed to maintain stable highwalls in the mined coal beds rather than simple surface-only expressions around identi fied buffers. An additional relatively deep box cut will be required in the southern one-half of the Gillette coal field to recover coal resources west of the Joint Line Railroad. The need for this additional box cut will result in a significant increase in overall mining costs for coal resources in that area. An important distinction of the SWPRB assessment area compared to the other PRB assessment areas is the absence of the extensive, thick, shallow WyodakAnderson coal zone. While no coal in the PRB is currently recovered by underground mining methods, nor is it expected to be in the near future, there are significant deep resources within the range of current underground mining tech nology. Underground resources for coal beds 10-20 ft thick and 500-2,000 deep were estimated at 304 BST. The mapping of individual coal beds for the first time throughout the entire PRB was required to complete an economic assessment of both available and recoverable coal resources and offers a unique perspective com pared to previous work, which relied on less effective net coal isopach maps. This in turn may provide new viewpoints regarding depositional environments of this extensive, exceptionally thick, coal sequence. Regional prefeasibility mine models were developed to conduct mining economic evaluations to estimate the portion of the available resources that meet the defini tion of reserves and recoverable coal. Estimates of reserves and resources are important, however, the relation between reserves and recoverable coal resources is equally significant in understanding the potential coal reserve base of the United States. The coal reserve base provides estimates of coal resources that are currently economic (reserves), and those recoverable resources that may become eco nomic using current technologies. This information is important from a national energy security and policy standpoint regardless of time frames. The cumulative results from the four PRB assessment areas are 24.5 BST of coal reserves and a total recover able coal resource (coal reserve base) of 162 BST in coal beds greater than 5 ft in thickness and less than a 10:1 stripping ratio. With continued favorable sales prices, increased pro ductivity, and technological advances in mining that posi tively affect economics, resources once considered to be subeconomic may be elevated to the status of reserves. There fore, reserve studies should be considered a cyclic process and models should be adjusted and assessed periodically using the most recent data, which uses the most current recovery technology and economics. Acknowledgments This report was produced through the efforts and coop eration of many people. Susan Tewalt, Michael Brownfield, Tom Judkins, and David Ferderer, all presently or formerly of the USGS, provided in-depth technical reviews of the manuscript. Nicholas Jones (formerly with the Wyoming State Geological Survey), the staff of the Wyoming State Geological Survey, and Jay A. Gunderson of the Montana Bureau of Mines and Geology, supplied data and information pertain ing to the Powder River Basin. 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Glossary 47 Glossary The present study includes determinations of original, available, and recoverable coal resources; reserves, and reserves, which are economically recoverable coal resources. This termi nology has been used in many USGS coal studies (see Wood and others, 1983; Carter and Gard ner, 1989; Eggleston and others, 1990; and Molnia and others, 1999). The following definitions were applied in this resource evaluation: Coal resources Naturally occurring concen trations or deposits of coal in the Earth's crust, in such forms and amounts that economic extraction is currently or potentially feasible (Wood and others, 1983). Continuous mining Mining in which the con tinuous miner machine cuts or rips coal from the face and loads it onto conveyors or into shuttle cars in a continuous operation (Thrush, 1968). D Delta The low, nearly flat, alluvial tract of land at or near the mouth of a river, com monly forming a triangular or fan-shaped plain of considerable area (Jackson, 1997). Deltaic Pertaining to or characterized by a delta (Jackson, 1997). Demonstrated coal reserve base (DBR) Includes publicly available data on coal mapped to measured and indicated degrees of accuracy and found at depths and in coalbed thickness considered technologically minable at the time of determinations (U.S. Department of Energy, 2013). Dip (dipping) The angle at which a bed, stratum, or vein is inclined from the horizontal (Thrush, 1968). Discounted cash flow (DCF) The stream of the net after-tax cash flows where the cash outlays include all operating costs, taxes, and investment costs, and where revenues include cash payments of product sales (Association for the Advancement of Cost Engineering, 1997). F Facies The aspect, appearance, and charac teristics of a rock unit, usually reflecting the conditions of its origin, especially as differenti ating the unit from adjacent or associated units (Jackson, 1997). A Alluvial Pertains to or composed of alluvium (sediments) deposited by a stream (Jackson, 1997). Available coal resources Remaining coal resources that are thick and shallow enough to be mined by either surface or underground methods and that are unencumbered by land-use, environmental, societal, regulatory, or techno logic restrictions as they may apply in a specific State or region (Carter and Gardner, 1989). B Box cut The initial cut driven in a property, where no open side exists; this results in a high wall on both sides of the cut (Thrush, 1968). Chronostratigraphic The organization of rock strata into units on the basis of their age or time of origin (Jackson, 1997). Coalbed methane (CBM) Primary coal bed gas collected from unmined coal beds (Clarkeenergy, http//:Clarke-energy.com/gas-type/coalgas, accessed on May 7, 2013). Coal reserves Virgin or accessed parts of a coal reserve base which could be economically extracted or produced at the time of determina tion considering environmental, legal, and tech nologic constraints. The term "reserves" need not signify that extraction facilities are in place or operative. Reserves include only recoverable coal; thus, terms such as "extractable reserves" are redundant and are not a part of the classifi cation system. Reserves can be categorized as "measured" and "indicated," as underground or surface minable, by thickness of overburden, by thickness of coal in the bed, and by various qual ity factors (Wood and others, 1983). Coal reserve base The tonnage estimate for coal consisting of the sum of the estimates for measured and indicated reserves, marginal reserves, and a part of the measured and indicated subeconomic resources (Wood and others, 1983).
48 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana A fracture or fracture zone along which there has been displacement of the two sides relative to one another parallel to the fracture (Thrush, 1968). Fluvial Of or pertaining to a river or rivers (Jackson, 1997). Freight on Board (FOB) A reference to the place where purchased goods will be shipped without transportation charge. G Gytta A dark, pulpy, freshwater mud charac terized by abundant organic matter that is more or less cohesive, and deposited or precipitated in a marsh or in a lake whose waters are rich in nutrients and oxygen (Jackson, 1997). H Headgate The primary roadway access and egress through which equipment, personnel, and supplies are provided to a longwall face, through which coal is conveyed to the surface, and through which fresh air flows (Stermole, 1974). Hypothetical resources Tonnage estimates computed by extrapolation of thicknesses of coal for a radius beyond 3.0 mi (4.8 km) from a point of measurement. Hypothetical resources are a class of undiscovered resources that are either similar to known coal deposits which may be reasonably expected to exist in the same region under analogous geologic conditions, or are an extension from inferred resources (Wood and others, 1983). Identified resources Resources whose loca tions, rank, quality, and quantity are known or estimated from specific geologic evidence. Identified coal resources include economic, marginally economic, and subeconomic components. To reflect varying distances from points of control or reliability, these subdivi sions can be divided into demonstrated and inferred, or preferably into measured, indicated, and inferred (Wood and others, 1983). Indicated resources Tonnage estimates com puted by extrapolation of thicknesses of coal for a radius of 0.25 to 0.75 mi (0.4 to 1.2 kilo meters [km]) from a point of measurement (Wood and others, 1983). Inferred resources Tonnage estimates com puted by extrapolation of thicknesses of coal for a radius of 0.75 to 3.0 mi (1.2 to 4.8 km) from a point of measurement (Wood and others, 1983). In-place resources Resources that currently exist within a geographic area. The term inplace resources is equal to the term available resources in this report. Interburden The rock between two coal beds. When two potentially minable coal beds occur within a minimum acceptable distance above or below one another, one will not be mined-often the thinner of the two (Carter and Gardner, 1989). Interdeltaic A term used by Ayers and Kaiser (1984) to describe coal beds forming between deltas. Land-use restrictions Constraints placed upon mining by societal policies to protect those sur face features or entities that could be harmed by mining. Since laws and regulations can be modi fied or repealed, the restrictions, including indus trial and environmental restrictions, may change. Land use restrictions include railroads, cities, and towns, airports, and Interstate highways. Longwall mining A system of underground mining on straight faces 80 yards (73 m) or more in length (Thrush, 1968). M Measured resources Tonnage estimates com puted by extrapolation of thicknesses of coal for a radius of 0.25 mi (0.4 km) from a point of measurement (Wood and others, 1983). Mined coal Coal that has already been extracted from a deposit (Association for the Advancement of Cost Engineering, 1999). A small piece of marshy, swampy, or boggy ground (wet spongy earth) (Jackson, 1997). O Original coal resource The total amount of coal in-place before production. Where mining has occurred, the total of original resources is the sum of the identified resources, undiscov ered resources, coal produced, and coal lost in mining (Wood and others, 1983). Overburden Rock including coal or uncon solidated material that overlies a specified coal bed. Overburden is reported in feet or meters and is used to classify the depth to an underlying coal bed (Wood and others, 1983). That part of a rock formation (coal bed) that appears at the surface of the ground (Thrush, 1968).
Glossary 49 P A soil that formed on a landscape in the past with distinctive morphological fea tures resulting from a soil-forming environment that no longer exists at the site (Jackson, 1997). A thin layer of stratum or non coaly material within a coal bed which does not exceed the thickness of coal in either the directly underlying or overlying benches (Wood and others, 1983). An unconsolidated deposit of seminar bonized plant remains in a water-saturated envi ronment, such as a bog or fen (Jackson, 1997). R Recoverable coal resource Coal that is or can be extracted from a coal bed during min ing. The term "recoverable" should be used in combination with "resources" and not with "reserves" (Wood and others, 1983). Reliability categories Based on the distance from points of measurement or sampling. The measured, indicated, inferred, and hypotheti cal resource categories, as defined, indicate the relative reliability of tonnage estimates as related to distance from points of thickness control of particular parts of a coal deposit. The reliability categories are not indicative of the reliability of the basic data (that is, the accuracy of coal mea surements, or the accuracy of location of the coal outcrop). It is assumed that all basic data used in resource estimation have been judged reliable by the estimator and that unreliable data have been discarded (Wood and others, 1983). Remaining resources Represent resources in the ground after subtracting coal that has been previously mined from the original resource (Carter and Gardner, 1989). Restrictions to mining Include land use restrictions, technical limitations, and unsuit ability criteria that would prohibit mining. Royalty A lease by which the owner or lessor grants to the lessee the privilege of mining and operating the land in consideration of payment (Thrush, 1968). S Strip (stripping) ratio Represents the ratio of the volume of overburden or interburden (waste) that must be removed to gain access to a unit amount of coal. For this assessment, the ratio is expressed as cubic yards of overbur den to tons of coal. The stripping ratio can be approximated by dividing the total thickness of waste by the total thickness of coal. For example, given a coal bed, 10.0 ft thick, at 100 ft in depth, the stripping ratio would be 10:1 (in cubic yards to a ton of coal) (Thrush, 1968). Subaerial Means conditions and processes, such as erosion, existing or operating in the open air on or immediately adjacent to the land surface (Jackson, 1997). Subbituminous coal Rank class of nonag glomerating coals having a heat value con tent of more than 8,300 Btu and less than 11,500 Btu on a moist, mineral-matter-free basis (Wood and others, 1983). Surface coal mining (strip) Mining at or near the ground surface and is generally done where the overburden can be removed economically. A strip mine is a surface mine in which the overburden is removed from a coalbed before the coal is removed (Thrush, 1968). T Tailgate The secondary roadway access or egress from a longwall face and through which return air flows (Society of Mining Engineers, 1973). Technical restrictions Constraints, relating to economics and safety, placed upon mining by the state of technology or prescribed by law. These restrictions can change with advances in science and technology, or modifications in the law. In the report, some geologic factors are included as technologic restrictions. Techni cal restrictions include coal between 2.5 ft and 5.0 ft thick and areas of clinker. U Unsuitability criteria Specific legal con straints used to determine if an area can be mined by surface mining methods. These include, but are not limited to, Federal land systems, dwellings, and alluvial valley floors.
Figures
Figures 53 Figure 1. Map showing location of the Powder River Basin, Wyoming and Montana. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. Birney Decker Colstrip Broadus Birney Gillette Buffalo Wright Gillette Miles City Miles City Buffalo Douglas Casper Douglas Moorcroft Moorcroft Decker Colstrip Broadus Ashland Ashland Forsyth Forsyth Lame Deer Lame Deer Casper Wright Glenrock Sheridan
CROW RESERVATION CROW RESERVATION NORTHERN CHEYENNE RESERVATION NORTHERN CHEYENNE RESERVATION Powder River Basin Powder River Basin NIOBRARA COUNTY CONVERSE COUNTY BIG HORN COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY POWDER RIVER COUNTY CROOK COUNTY CAMPBELL COUNTY WESTON COUNTY NATRONA COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES BURLINGTON NORTHERN SANTA FE RAILROAD BURLINGTON NORTHERN SANTA FE RAILROAD BURLINGTON NORTHERN SANTA FE AND UNION PACIFIC RAILROADS BURLINGTON NORTHERN SANTA FE AND UNION PACIFIC RAILROADS
54 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 2. Map showing location of individual assessment areas in the Powder River Basin, Wyoming and Montana. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. Glenrock Birney Decker Colstrip Broadus Birney Gillette Buffalo Wright Gillette Miles City Miles City Buffalo Douglas Casper Douglas Moorcroft Decker Colstrip Broadus Ashland Ashland Forsyth Forsyth Lame Deer Lame Deer Casper Wright Glenrock Glenrock Sheridan Sheridan ANTELOPE MINE NORTH ANTELOPE/ ROCHELLE MINE JACOBS RANCH MINE BLACK THUNDER MINE CORDERO ROJO MINE COAL CREEK MINE WYODAK MINE DRY FORK MINE BUCKSKIN MINE BELLE AYR MINE CABALLO MINE RAWHIDE MINE ROSEBUD MINE ABSALOKA MINE BIG SKY MINE (ABANDONED) SPRING CREEK MINE DECKER MINES DAVE JOHNSTON MINE (ABANDONED) BIG HORN MINE EAGLE BUTTE MINE CARTER COUNTY CROOK COUNTY NIOBRARA COUNTY CONVERSE COUNTY CONVERSE COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY WESTON COUNTY NATRONA COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES Gillette coal field assessment area (OFR-2008-1202) Northern Wyoming Powder River Basin assessment area (USGS OFR-2010-1294) Northern Wyoming Powder River Basin assessment area (USGS OFR-2010-1294) Montana Powder River Basin assessment area (USGS OFR-2012-1111) Montana Powder River Basin assessment area (USGS OFR-2012-1111) Southwestern Wyoming Powder River Basin assessment area (USGS OFR-2011-1134) Southwestern Powder River Basin assessment area (USGS OFR-2011-1134) Belco lease area Belco lease area Stevens North lease area Stevens South lease area Stevens North lease area East Gillette coal field extension East Gillette coal field extension Stevens South lease area PSO lease area PSO lease area Otter Creek lease area Otter Creek lease area
Figures 55 Figure 3. Map showing structure contours drawn on the top of the Tullock Member of the Fort Union Formation. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. CONVERSE COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CROOK COUNTY CAMPBELL COUNTY CAMPBELL COUNTY WESTON COUNTY NATRONA COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY MONTANA WYOMING MONTANA WYOMING 1,250 1,500 1,750 2,000 2,250 2,500 2,750 1,000 3,000 -250 -500 -750 -1,000 -1,250 3,000 4,000 4,500 4,250 4,000 3,750 3,500 3,000 WYOMING MONTANA Powder River Basin LOCATION MAP 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES EXPLANATION Contour (feet) Basin axis Contour interval 250 feet (76 meters) 3,000 Powder River Basin
56 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 4. Map showing generalized surface geology of the Powder River Basin, Wyoming and Montana. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY NIOBRARA COUNTY CONVERSE COUNTY CONVERSE COUNTY NATRONA COUNTY CARTER COUNTY WYOMING MONTANA Powder River Basin LOCATION MAP 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES Basin axis (approximately where dashed) Quaternary alluvium and terrace deposits Tertiary White River Formation Tertiary Wasatch Formation Tongue River Member Tullock Member Tertiary Fort Union Formation (undifferentiated) EXPLANATION Lebo Shale Member Tongue River and Lebo Shale Members Tft Tfl Tftrl Tftr Tfu Tw Twr Qal Tftr Tw Tftrl Tftrl Tfu Tft Qal Qal Twr Twr Tfl Tfl Powder River Basin Powder River Basin WYOMING MONTANA
Figures 57 Figure 5. Generalized stratigraphic column for the Powder River Basin, Wyoming and Montana. Wyoming Montana Quaternary Age Stratigraphic units in the Powder River Basin Late Cretaceous Tertiary Wasatch Formation Lance Formation Hell Creek Formation Fox Hills Sandstone Bearpaw Shale Mesaverde Formation Pierre Shale Tongue River Member Lebo Shale Member Fort Union Formation Eocene Oligocene Paleocene White River Formation Surficial deposits Tullock Member Cody Shale Niobrara Formation Carlile Shale Greenhorn Formation Belle Fourche Shale Mowry Shale Muddy Sandstone Thermopolis Shale Fall River Formation Lakota Formation Frontier Formation Early Cretaceous Cretaceous
58 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 6. Map showing location of coal fields in the Powder River Basin, Wyoming and Montana. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY BIG HORN COUNTY TREASURE COUNTY CUSTER COUNTY FALLON COUNTY NIOBRARA COUNTY NATRONA COUNTY ROSEBUD COUNTY CARTER COUNTY POWDER RIVER COUNTY CROOK COUNTY CAMPBELL COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY BIG HORN COUNTY TREASURE COUNTY CUSTER COUNTY FALLON COUNTY NIOBRARA COUNTY CONVERSE COUNTY NATRONA COUNTY ROSEBUD COUNTY Little Powder River coal field Powder River coal field Moorhead coal field North Extension Sheridan coal field Sheridan coal field Spotted Horse coal field Spotted Horse coal field Gillette coal field Buffalo coal field Buffalo coal field Barber coal field Sussex coal field Pumpkin Buttes coal field East Gillette coal field extension Forsyth coal field Ashland coal field Coalwood coal field Birney-Broadus coal field Miles City coal field Rosebud coal field Mizpah coal field Dry Cheyenne coal field Lost Spring coal field Glenrock coal field Powder River Basin Powder River Basin
Figures 59 Figure 7. Map showing location of significant clinker in the Powder River Basin, Wyoming and Montana. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CROOK COUNTY SHERIDAN COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY NIOBRARA COUNTY WESTON COUNTY NATRONA COUNTY WASHAKIE COUNTY JOHNSON COUNTY BIG HORN COUNTY NIOBRARA COUNTY CONVERSE COUNTY CAMPBELL COUNTY CONVERSE COUNTY CARTER COUNTY CROOK COUNTY CAMPBELL COUNTY WESTON COUNTY NATRONA COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY MONTANA WYOMING MONTANA WYOMING Clinker (burned coal) Clinker (burned coal) WYOMING MONTANA Powder River Basin LOCATION MAP 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES Powder River Basin Powder River Basin
60 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 8. West-east cross section A-A' showing subsurface distribution of significant coal beds through the southern part of the Powder River Basin, Wyoming. B Powder River Basin WYOMING MONTANA A A' Gillette Wright LOCATION MAP 20 MILES 20 KILOMETERS 2,000 3,000 4,000 5,000 ELEVATION ABOVE SEA LEVEL (FEET) 1,000 A Southwestern Wyoming Powder River Basin Wyodak-Anderson coal zone (Flores and Bader, 1999b) Smith (Big George) Werner Rosebud/Knobloch Axis of the basin Gates/Wall A' Roland (Baker) Smith Canyon Lower Canyon Anderson Dietz 3 Pawnee Flowers-Goodale Roberts/Terret Wyodak-Anderson coal zone (Flores and Bader, 1999b) Gillette coal field East Gillette coal field extension Approximate land surface Felix
Figures 61 Figure 9. West-east cross section B-B' showing subsurface distribution of significant coal beds through the central part of the Powder River Basin, Wyoming. Powder River Basin WYOMING MONTANA B B' Sheridan LOCATION MAP 20 MILES 20 KILOMETERS 2,000 3,000 4,000 ELEVATION ABOVE SEA LEVEL (FEET) 1,000 B B' Roland (Baker) Smith Anderson Dietz 3 Canyon Lower Canyon Werner Gates/Wall Pawnee Rosebud/Knobloch Flowers-Goodale Roberts/Terret Axis of the basin Approximate land surface Wyodak-Anderson coal zone (Flores and Bader, 1999b)
62 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 10. North-south cross section C-C' showing subsurface distribution of significant coal beds through the Powder River Basin, Wyoming and Montana. Powder River Basin WYOMING MONTANA C' Gillette Wright LOCATION MAP 20 MILES 20 KILOMETERS 2,000 3,000 4,000 5,000 ELEVATION ABOVE SEA LEVEL (FEET) 1,000 Approximate land surface Felix Anderson Dietz 3 Werner Gates/Wall Pawnee Rosebud/Knobloch Flowers-Goodale Roberts/Terret Wyodak-Anderson coal zone (Flores and Bader, 1999b) Wyodak-Anderson coal zone (Flores and Bader, 1999b) Canyon Roland (Baker) Lower Canyon MONTANA WYOMING C' Smith
Figures 63 Figure 11. Map showing approximate location of faults within the Powder River Basin, Wyoming and Montana. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY CONVERSE COUNTY BIG HORN COUNTY TREASURE COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES Faults (approximate) Basin axis (approximate where dashed) Faults (approximate) Basin axis (approximate where dashed) Powder River Basin Powder River Basin
64 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 12. Map showing locations of mines, lease areas, and average coal quality basis within the Powder River Basin, Wyoming and Montana. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY CONVERSE COUNTY BIG HORN COUNTY TREASURE COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES ABSALOKA MINE ROSEBUD MINE BIG SKY MINE (abandoned) SPRING CREEK MINE DECKER MINES BIG HORN MINE (abandoned) DAVE JOHNSTON MINE (abandoned) ANTELOPE MINE NORTH ANTELOPE/ ROCHELLE MINE JACOBS RANCH MINE (abandoned) BLACK THUNDER MINE CORDERO ROJO MINE COAL CREEK MINE (abandoned) WYODAK MINE DRY FORK MINE BUCKSKIN MINE BELLE AYR MINE CABALLO MINE RAWHIDE MINE EAGLE BUTTE MINE Stevens North lease area Stevens South lease area PSO lease area British thermal unit per pound average=8,750 Ash average=8.80 percent Sulfur average=0.75 percent Sheridan coal field area Decker/Spring Creek area Colstrip area Gillette coal field/north Gillette coal field/middle Lake DeSmet area Otter Creek lease area Sheridan coal field area Decker/Spring Creek area Colstrip area Glenrock coal field Glenrock coal field Gillette coal field/north Gillette coal field/middle Lake DeSmet area Otter Creek lease area Gillette coal field/south British thermal unit per pound average=9,400 Ash average=4.15 percent Sulfur average=0.39 percent British thermal unit per pound average=8,110 Ash average=5.50 percent Sulfur average=0.15 percent British thermal unit per pound average=9,300 Ash average=5.7 percent Sulfur average=0.60 percent British thermal unit per pound average=6,800 Ash average=15.0 percent Sulfur average=0.70 percent British thermal unit per pound average=7,581 Ash average=12.1 percent Sulfur average=0.45 percent British thermal unit per pound average=8,807 Ash average=5.43 percent Sulfur average=0.28 percent British thermal unit per pound average=8,459 Ash average=5.86 percent Sulfur average=0.35 percent British thermal unit per pound average=8,203 Ash average=6.29 percent Sulfur average=0.39 percent Belco lease area Lake DeSmet Powder River Basin
Figures 65 Figure 13. Coal bed and coal zone names used in this assessment and previous publications in the Powder River Basin, Wyoming and Montana. Formation name Kent and others (1980) Pierce and others (1990) Flores and others (1999) Gillette coal field, Luppens and others (2008) Northern Wyoming Powder River Basin, Scott and others (2010) Southwestern Wyoming Powder River Basin, Osmonson and others (2011) Montana Powder River Basin, Haacke and others (2013) PRB this assessment Coal bed names Lake DeSmet coal zone Wasatch Upper Healy Upper Healy, Healy Upper Healy Healy/Lower Ulm Healy Murray Murray Ucross Ucross Ucross Upper Felix Upper Felix Felix Felix Felix Felix Felix Lower Felix Lower Felix Lower Felix Fort Union (Tongue River Member) Roland (Upper Rider) Roland (Upper Rider) Roland (Upper Rider) Roland (Lower Rider) Roland (Lower Rider) Smith Roland/Badger Roland Roland (Baker, 1929) Roland (Baker, 1929) Roland (Baker, 1929) Roland (Baker, 1929) Roland (Taff, 1909) Roland (Taff, 1909) Roland (Taff, 1909) Wyodak or Upper Wyodak (Anderson/ Canyon) Wyodak-Anderson coal zone=Smith (Swartz), Badger, School, Sussex, Big George, Wyodak, Anderson, Dietz, Canyon (Monarch), Werner Upper Smith Wyodak-Anderson coal zone Smith Smith Smith Smith Smith Anderson Rider Anderson Upper Rider Anderson Lower Rider Upper Wyodak Anderson Anderson Anderson Anderson Anderson Lower Anderson Lower Anderson Dietz 1 Dietz 1 Dietz 1 Dietz 2 Dietz 2 Dietz 2 Dietz Dietz 3 Dietz 3 Dietz 3 Dietz 3 Dietz 4 Dietz 4 Dietz 4 Upper Canyon Cox Upper Canyon/Cox Canyon Canyon Canyon Canyon Canyon Canyon Lower Canyon Lower Canyon Lower Canyon Lower Canyon Upper Ferry Ferry Ferry Ferry Werner Lower Wyodak Werner Werner Werner Werner/Cook Werner/Cook Upper Otter Otter Otter Otter Otter Gates/Kennedy Upper Kennedy Gates Gates Gates Gates/Wall Gates/Wall Pawnee Pawnee Pawnee Pawnee Pawnee Brewster-Arnold Brewster-Arnold Odell Odell Odell Cache Cache A Zone Upper Rosebud/51 Rosebud Dietz 1 Rosebud/Knobloch Rosebud/Knobloch Calvert Calvert McKay Dietz 2 McKay/Nance McKay/Nance Lower McKay/52 Dietz 3 Flowers-Goodale Flowers-Goodale Upper Witham Upper Witham Robinson Robinson/Witham Robinson/Witham Roberts Roberts Roberts/Terret Roberts/Terret Burley Upper Stag Lower Stag
66 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 14. Flow chart showing generalized U.S. Geological Survey methodology used for coal resource and reserve assessment. Correlate coal beds Create coal bed models Create land-use and technical restrictions by bed Coal bed geology (extent, thickness, partings, structure, overburden) Factors affecting extraction of coal (land-use and technical restrictions) State and county jurisdiction and coal ownership Coal quality information, coal sales price, tax information Calculate tonnages and areas for original, mined out, restricted and available resources by bed Create mine models (by stripping ratio) Calculate available resources by mine model Calculate mining costs by mine model PHASE THREE—RESOURCE/RESERVE ASSESSMENT PHASE TWO—GEOLOGIC AND GEOGRAPHIC INFORMATION SYSTEM MODELING PHASE ONE—DATA COLLECTION
Figures 67 Figure 15. Map showing mines and nonproprietary drill holes and paleochannels within the Anderson coal bed in the Powder River Basin, Wyoming and Montana. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY TREASURE COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Drill hole location (approximate) Mine location (approximate) EXPLANATION Paleo channel areas (approximate) 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES Powder River Basin Powder River Basin
68 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 16. Cross section A-A' showing correlations used in the U.S. Geological Survey Miscellaneous Investigations Series Map I-1959-D by Molnia and Pierce (1992). A A' B B' Wright Gillette coal field Gillette A A' Gillette coal field Wright LOCATION MAP 40-005-33013 49-005-24816 Upper Wyodak (Anderson) Lower Wyodak (Canyon) Felix Roland 49-005-24358 Oil and gas well substituted for original well 49-005-23052 49-005-24213 Total distance is approximately 9.0 miles (14.5 km) Total distance is approximately 20.5 miles (30.0 kilometers)
Figures 69
s Investigations Series B' showing comparison of coal bed correlations made in the Gillette coal field report to the U.S. Geological Survey Miscellaneou - Cross section B
Figure 17. Map I-1959-D by Molnia and Pierce (1992).
70 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 18. Isopach map showing combined thickness of the Smith, Anderson, and Canyon coal beds and areas of thin or absent coal ("want area" after Flores and others, 2010) within the Powder River Basin, Wyoming and Montana. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY TREASURE COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION 300 and greater Mine area Thickness (feet) 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES Powder River Basin Powder River Basin "Want Area" "Want Area"
Figures 71 Figure 19. Map showing land-use restrictions in the Powder River, Wyoming and Montana. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY CONVERSE COUNTY BIG HORN COUNTY TREASURE COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING
WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Alluvial valley floor
Area of joint line box cut offset Mine area
40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES Powder River Basin Powder River Basin Broadus Airport Broadus Airport Broadus Airport Montana Fish, Wildlife, and Parks Conservation Easement
Montana Fish, Wildlife, and Parks Conservation Easement
Twelve Mile DamMontana Fish, Wildlife, and Parks
Montana Land Reliance Conservation Easement
Twelve Mile DamMontana Fish, Wildlife, and Parks
Fort Keogh National Wildlife Refuge
Fort Keogh National Wildlife Refuge
Montana Land Reliance Conservation Easement
Custer National Forest
Custer National Forest
Rosebud Battlefield State Park
Rosebud Battlefield State Park
TONGUE RIVER RESERVOIR AND STATE PARK TONGUE RIVER RESERVOIR AND STATE PARK WOLF MOUNTAINS BATTLESITE NATIONAL HISTORIC LANDMARK
Wolf Mountains Battlesite National Historic Landmark
THUNDER BASIN NATIONAL GRASSLANDS BURLINGTON NORTHERN SANTA FE RAILROAD THUNDER BASIN NATIONAL GRASSLANDS BURLINGTON NORTHERN SANTA FE RAILROAD THUNDER BASIN NATIONAL GRASSLANDS Hilight Gas Plant
THUNDER BASIN NATIONAL GRASSLANDS Hilight Gas Plant
BURLINGTON NORTHERN SANTA FE AND UNION PACIFIC RAILROADS BURLINGTON NORTHERN SANTA FE AND UNION PACIFIC RAILROADS Lake DeSmet
Lake DeSmet
Ye o w s t o n e R Ye o w s t o n e R N o r t h Pl a t t e
R N o r t h Pl a t t e
R Be ll Fo uche
R er Be ll Fo uche
R er Miles City Miles City Broadus Broadus Broadus Colstrip Colstrip Decker Decker Clearmont Clearmont Sheridan Buffalo Sheridan Buffalo Gillette Gillette Wright Wright Rolling Hills Glenrock Casper Douglas Ranchester
72 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 20. Map showing coal mineral estate ownership in the Powder River Basin, Wyoming and Montana. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY CONVERSE COUNTY CONVERSE COUNTY BIG HORN COUNTY TREASURE COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Private coal State coal Federal coal 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES Powder River Basin Powder River Basin
Figures 73 Figure 21. Illustration showing the effect of coal-bed depth upon restricted resource because of mine-pit highwall setback requirements. Coal bed Mine accessible coal-bearing rock Additional restriction due to required mine pit highwall angle (coal unavailable for mining) Surface restriction and buffer projected downward (coal unavailable for mining) Restriction to mining EXPLANATION Horizontal limits of vertically projected surface restriction and buffer Mine bench Mine bench Surface restriction Buffer distance Buffer distance 2,144 feet 300 feet 300 feet 26° 26° 200 feet 500 feet 858 feet
74 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 22. Map showing location of areas of low, moderate, and high coalbed methane potential in the Powder River Basin, Wyoming and Montana. Campbell Powder River Birney 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY CONVERSE COUNTY BIG HORN COUNTY TREASURE COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES Powder River Basin Powder River Basin Area of low estimated coalbed methane potential Area of low estimated coalbed methane potential Area of moderate estimated coalbed methane potential Area of moderate estimated coalbed methane potential Area of high estimated coalbed methane potential Area of high estimated coalbed methane potential Area of low estimated coalbed methane potential Area of low estimated coalbed methane potential Area of low estimated coalbed methane potential Area of low estimated coalbed methane potential
Figures 75 Figure 23. Coal bed stratigraphy, original and available resources, and maximum and average thicknesses for coal beds in the Powder River Basin, Wyoming and Montana. Coal bed stratigraphy, original and available resources, and thickness Formation name Coal beds identified in this assessment Original resources calculate (millions of tons) Available resources calculated (millions of tons) Maximum thickness (feet) Average thickness (feet) Wasatch Upper Healy 6,863 5,327 Healy/Lower Ulm 13,004 10,738 Murray 2,664 Ucross 6,808 4,492 Upper Felix 2,122 1,205 Felix 18,759 16,784 Lower Felix 19,385 14,929 Fort Union (Tongue River Member) Roland Upper Rider 13,506 8,304 Roland Lower Rider 3,257 1,693 Roland (Baker, 1929) 47,774 43,336 Roland (Taff, 1909) 3,403 1,290 Upper Smith 1,036 Wyodak-Anderson coal zone Smith 126,433 122,868 Anderson Upper Rider Anderson Lower Rider Anderson 125,481 101,825 Lower Anderson 3,382 2,039 Dietz 1 1,138 Dietz 2 2,992 2,032 Dietz 3 50,880 45,063 Dietz 4 1,765 Upper Canyon/Cox 5,968 4,711 Canyon 147,450 135,454 Lower Canyon 59,528 52,056 Upper Ferry Ferry 6,396 4,277 Werner/Cook 73,986 63,353 Upper Otter Otter 71,021 64,310 Gates/Wall 66,426 57,851 Pawnee 24,498 16,964 Brewster-Arnold 1,968 Odell 11,676 6,581 Cache 3,303 A Zone Upper Rosebud/S1 Rosebud/Knobloch 64,401 47,091 Calvert 1,162 McKay/Nance 33,289 22,614 Lower McKay/S2 Flowers-Goodale 60,544 51,064 Upper Witham Robinson/Witham 20,677 15,007 Roberts/Terret 51,866 44,467 Burley 1,632 Upper Stag 1,870 Lower Stag TOTAL TONS 1,161,851 974,751
76 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 24. Isopach map of the Upper Healy coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. POWDER RIVER COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY TREASURE COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES EXPLANATION Thickness (feet) Powder River Basin Powder River Basin
Figures 77 Figure 25. Map showing depth to the top of the Upper Healy coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. POWDER RIVER COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY TREASURE COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES EXPLANATION Depth to top of coal in feet Basin axis 1,000 1,500 Powder River Basin Powder River Basin
78 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 26. Isopach map of the Healy/Lower Ulm coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 79 Figure 27. Map showing depth to the top of the Healy/Lower Ulm coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Depth to top of coal in feet EXPLANATION Basin axis 1,000 1,500 Powder River Basin Powder River Basin
80 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 28. Isopach map of the Murray coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin Thickness in feet EXPLANATION LOCATION MAP Powder River Basin Powder River Basin
Figures 81 Figure 29. Map showing depth to the top of the Murray coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Depth to top of coal in feet EXPLANATION Basin axis 1,000 1,500 Powder River Basin Powder River Basin
82 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 30. Isopach map of the Ucross coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 83 Figure 31. Map showing depth to the top of the Ucross coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet Basin axis 1,000 1,500 Powder River Basin Powder River Basin
84 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 32. Isopach map of the Upper Felix coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 85 Figure 33. Map showing depth to the top of the Upper Felix coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet Basin axis 1,000 Powder River Basin Powder River Basin
86 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 34. Isopach map of the Felix coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 87 Figure 35. Map showing depth to the top of the Felix coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
88 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 36. Isopach map of the Lower Felix coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 89 Figure 37. Map showing depth to the top of the Lower Felix coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
90 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 38. Isopach map of the Roland (Upper Rider) coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 91 Figure 39. Map showing depth to the top of the Roland (Upper Rider) coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
92 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 40. Isopach map of the Roland (Lower Rider) coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 93 Figure 41. Map showing depth to the top of the Roland (Lower Rider) coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
94 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 42. Isopach map of the Roland (Baker) coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 95 Figure 43. Map showing depth to the top of the Roland (Baker) coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
96 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 44. Isopach map of the Roland (Taff) coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 97 Figure 45. Map showing depth to the top of the Roland (Taff) coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
98 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 46. Isopach map of the Upper Smith coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 99 Figure 47. Map showing depth to the top of the Upper Smith coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
100 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 48. Isopach map of the Smith coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION 100 and greater Powder River Basin Powder River Basin
Figures 101 Figure 49. Map showing depth to the top of the Smith coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 3,000 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
102 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 50. Isopach map of the Anderson Upper Rider coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 103 Figure 51. Map showing depth to the top of the Anderson Upper Rider coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
104 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 52. Isopach map of the Anderson Lower Rider coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 105 Figure 53. Map showing depth to the top of the Anderson Lower Rider coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 3,000 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
106 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 54. Isopach map of the Anderson coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION 100 and greater Powder River Basin Powder River Basin
Figures 107 Figure 55. Map showing depth to the top of the Anderson coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 4,000 3,000 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
108 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 56. Isopach map of the Lower Anderson coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 109 Figure 57. Map showing depth to the top of the Lower Anderson coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
110 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 58. Isopach map of the Dietz 1 coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 111 Figure 59. Map showing depth to the top of the Dietz 1 coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
112 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 60. Isopach map of the Dietz 2 coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 113 Figure 61. Map showing depth to the top of the Dietz 2 coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
114 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 62. Isopach map of the Dietz 3 coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION 100 and greater Powder River Basin Powder River Basin
Figures 115 Figure 63. Map showing depth to the top of the Dietz 3 coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 4,000 3,000 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
116 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 64. Isopach map of the Dietz 4 coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 117 Figure 65. Map showing depth to the top of the Dietz 4 coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
118 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 66. Isopach map of the Upper Canyon (Cox) coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 119 Figure 67. Map showing depth to the top of the Upper Canyon (Cox) coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 4,000 3,000 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
120 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 68. Isopach map of the Canyon coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION 100 and greater Powder River Basin Powder River Basin
Figures 121 Figure 69. Map showing depth to the top of the Canyon coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 4,000 3,000 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
122 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 70. Isopach map of the Lower Canyon coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 123 Figure 71. Map showing depth to the top of the Lower Canyon coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 4,000 3,000 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
124 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 72. Isopach map of the Upper Ferry coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 00' 30' 00' 30' 00' 30' 00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 125 Figure 73. Map showing depth to the top of the Upper Ferry coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Depth to top of coal in feet EXPLANATION Basin axis 1,000 1,500 Powder River Basin Powder River Basin
126 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 74. Isopach map of the Ferry coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 127 Figure 75. Map showing depth to the top of the Ferry coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 4,000 3,000 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
128 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 76. Isopach map of the Werner/Cook coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION 100 and greater Powder River Basin Powder River Basin
Figures 129 Figure 77. Map showing depth to the top of the Werner/Cook coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 4,000 3,000 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
130 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 78. Isopach map of the Upper Otter coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 131 Figure 79. Map showing depth to the top of the Upper Otter coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet Basin axis 4,000 3,000 2,500 1,000 1,500 2,000 Powder River Basin Powder River Basin
132 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 80. Isopach map of the Otter coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION 100 and greater Powder River Basin Powder River Basin
Figures 133 Figure 81. Map showing depth to the top of the Otter coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 4,000 3,000 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
134 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 82. Isopach map of the Gates/Wall coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION 100 and greater Powder River Basin Powder River Basin
Figures 135 Figure 83. Map showing depth to the top of the Gates/Wall coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 4,000 3,000 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
136 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 84. Isopach map of the Pawnee coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 137 Figure 85. Map showing depth to the top of the Pawnee coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 4,000 3,000 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
138 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 86. Isopach map of the Brewster-Arnold coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 139 Figure 87. Map showing depth to the top of the Brewster-Arnold coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
140 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 88. Isopach map of the Odell coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 141 Figure 89. Map showing depth to the top of the Odell coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 4,000 3,000 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
142 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 90. Isopach map of the Cache coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 143 Figure 91. Map showing depth to the top of the Cache coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
144 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 92. Isopach map of the A Zone coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 145 Figure 93. Map showing depth to the top of the A Zone coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Depth to top of coal in feet EXPLANATION Basin axis 1,000 Powder River Basin Powder River Basin
146 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 94. Isopach map of the Upper Rosebud coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 147 Figure 95. Map showing depth to the top of the Upper Rosebud coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet Basin axis 1,000 Powder River Basin Powder River Basin
148 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 96. Isopach map of the Rosebud/Knobloch coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. Ro sebud Cre ek 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin Little Wolf Mountains, approximate trend
Figures 149 Figure 97. Map showing depth to the top of the Rosebud/Knobloch coal bed within the Powder River Basin. Ro sebud Cre ek 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 4,000 3,000 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin Little Wolf Mountains, approximate trend
150 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 98. Isopach map of the Calvert coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. Ro sebud Cre ek 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin Little Wolf Mountains, approximate trend
Figures 151 Figure 99. Map showing depth to the top of the Calvert coal bed within the Powder River Basin. Ro sebud Cre ek 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin Little Wolf Mountains, approximate trend
152 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 100. Isopach map of the McKay/Nance coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. Ro sebud Cre ek 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin Little Wolf Mountains, approximate trend
Figures 153 Figure 101. Map showing depth to the top of the McKay/Nance coal bed within the Powder River Basin. Ro sebud Cre ek 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 4,000 3,000 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin Little Wolf Mountains, approximate trend
154 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 102. Isopach map of the Lower McKay coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. Ro sebud Cre ek 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin Little Wolf Mountains, approximate trend
Figures 155 Figure 103. Map showing depth to the top of the Lower McKay coal bed within the Powder River Basin. Ro sebud Cre ek 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin Little Wolf Mountains, approximate trend
156 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 104. Isopach map of the Flowers-Goodale coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 157 Figure 105. Map showing depth to the top of the Flowers-Goodale coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES Powder River Basin Powder River Basin CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 4,000 3,000 2,500 Basin axis 1,000 1,500 2,000
158 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 106. Isopach map of the Upper Witham coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 159 Figure 107. Map showing depth to the top of the Upper Witham coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet Basin axis Powder River Basin Powder River Basin
160 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 108. Isopach map of the Robinson/Witham coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. Ro sebud Cre ek 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin Little Wolf Mountains, approximate trend
Figures 161 Figure 109. Map showing depth to the top of the Robinson/Witham coal bed within the Powder River Basin. Ro sebud Cre ek 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 4,000 3,000 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin Little Wolf Mountains, approximate trend
162 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 110. Isopach map of the Roberts/Terret coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 163 Figure 111. Map showing depth to the top of the Roberts/Terret coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 4,000 3,000 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
164 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 112. Isopach map of the Burley coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 165 Figure 113. Map showing depth to the top of the Burley coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 4,000 3,000 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
166 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 114. Isopach map of the Upper Stag coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin Thickness in feet EXPLANATION LOCATION MAP Powder River Basin Powder River Basin
Figures 167 Figure 115. Map showing depth to the top of the Upper Stag coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet 4,000 3,000 2,500 Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
168 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 116. Isopach map of the Lower Stag coal bed showing extent of coal at least 1.0 foot thick within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet EXPLANATION Powder River Basin Powder River Basin
Figures 169 Figure 117. Map showing depth to the top of the Lower Stag coal bed within the Powder River Basin. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP EXPLANATION Depth to top of coal in feet Basin axis 1,000 1,500 2,000 Powder River Basin Powder River Basin
170 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 118. Pie diagram showing tonnages and percentages of individual coal beds in relation to the total 1.16 trillion short tons of original resources in the Powder River Basin, Wyoming and Montana. Gates/Wall 66 billion short tons 5.7 percent Rosebud/Knobloch 64 billion short tons 5.5 percent Flowers-Goodale 61 billion short tons 5.2 percent Roberts/Terret 52 billion short tons 4.5 percent Remaining 35 beds 216 billion short tons 18.6 percent Roland (Baker) 48 billion short tons 4.1 percent Smith 126 billion short tons 10.9 percent Anderson 125 billion short tons 10.8 percent Dietz 3 50 billion short tons 4.4 percent Canyon 147 billion short tons 12.7 percent Lower Canyon 60 billion short tons 5.1 percent Werner/Cook 74 billion short tons 6.4 percent Otter 71 billion short tons 6.1 percent
Figures 171 Figure 119. Isopach map of the Flowers-Goodale coal bed showing extent of resources at least 1.0 foot thick and location of lineaments described by Jones, 2010a, in the Powder River Basin, Wyoming and Montana. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 Lineament data modified from Jones (2010a) 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING Powder River Basin Powder River Basin Cross Creek Belle Creek Big Horn/Custer Parkman/Baker Tensleep/Harding LM Springen Ranch Rozet Weston/Hat Creek Sussex/Osage South Coyote Creek Gose Butte Fiddler Creek Clareton Trend Black Butte Lightning Creek Buffalo/Douglas Arminto/Upton Natrona/Ross Casper/Bill Orpha/Redbird Gillette/Keeline WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet Lineament and identifier EXPLANATION Rozet
172 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 120. Isopach map of the Roberts/Terret coal bed showing extent of resources at least 1.0 foot thick and location of lineaments described by Jones, 2010a, in the Powder River Basin, Wyoming and Montana. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING Powder River Basin Powder River Basin Cross Creek Belle Creek Big Horn/Custer Parkman/Baker Tensleep/Harding LM Springen Ranch Rozet Weston/Hat Creek Sussex/Osage South Coyote Creek Gose Butte Fiddler Creek Clareton Trend Black Butte Lightning Creek Buffalo/Douglas Arminto/Upton Natrona/Ross Casper/Bill Orpha/Redbird Gillette/Keeline WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet Lineament and identifier EXPLANATION Rozet Lineament data modified from Jones (2010a)
Figures 173 Figure 121. Isopach map of the Smith, Anderson, and Canyon coal beds showing extent of resources at least 5 feet thick and location of lineaments described by Jones, 2010a in the Powder River Basin, Wyoming and Montana. 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' T. 3 N. T. 5 N. T. 7 N. T. 33 N. T. 35 N. T. 37 N. T. 39 N. T. 41 N. T. 43N. T. 45 N. T. 47 N. T. 49 N. T. 51 N. T. 53N. T. 55 N. T. 57 N. T. 9 S. T. 7 S. T. 5 S. T. 3 S. T. 1 N. T. 1 S. R. 57 E. R. 55 E. R. 53 E. R. 51 E. R. 49 E. R. 45 E. R. 43 E. R. 41 E. R. 39 E. R. 37 E. R. 35 E. R. 47 E. R. 65 W. R. 67 W. R. 69 W. R. 71 W. R. 73 W. R. 75 W. R. 77 W. R. 81 W. R. 83 W. R. 85 W. R. 87 W. R. 79 W. 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY MONTANA WYOMING MONTANA WYOMING Powder River Basin Powder River Basin Cross Creek Belle Creek Big Horn/Custer Parkman/Baker Tensleep/Harding LM Springen Ranch Rozet Weston/Hat Creek Sussex/Osage South Coyote Creek Gose Butte Fiddler Creek Clareton Trend Black Butte Lightning Creek Buffalo/Douglas Arminto/Upton Natrona/Ross Casper/Bill Orpha/Redbird Gillette/Keeline WYOMING MONTANA Powder River Basin LOCATION MAP Thickness in feet Lineament and identifier Mine area EXPLANATION Rozet Lineament data modified from Jones (2010a) 300 and greater
174 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 122. Isopach map showing interburden thickness between the Anderson and Canyon coal beds in the Gillette coal field and location of lineaments described by Jones, 2010a in the Powder River Basin, Wyoming. T. 53 N. T. 52 N. T. 51 N. T. 50 N. T. 49 N. T. 48 N. T. 47 N. T. 45 N. T. 44 N. T. 43 N. T. 42 N. T. 41 N. T. 40 N. T. 39 N. R. 76 W. R. 75 W. R. 74 W. R. 73 W. R. 72 W. R. 71 W. R. 70 W. R. 69 W. R. 68 W. Buckskin Rawhide Eagle Butte Dry Fork Wyodak Caballo Belle Ayr Cordero Rojo Coal Creek Jacobs Ranch Black Thunder North Antelope/ Rochelle Antelope T. 46 N. Clareton Trend LM Arminto / Upton Gose Butte Buffalo / Douglas Gillette / Keeline Weston / Hat Creek South Coyote Creek Sussex / Osage Rozet Springen Ranch Lightning Creek Fiddler Creek Black Butte Tensleep/Harding 44°30' 44°00' 43°30' 105°45' 105°15' Wright Gillette CONVERSE COUNTY CAMPBELL COUNTY WESTON COUNTY CAMPBELL COUNTY 20 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 20 MILES WYOMING MONTANA Powder River Basin Gillette coal field LOCATION MAP Thickness in feet EXPLANATION Gillette coal field boundary Mine area and identifier Lineament and identifier Rozet Lineament data modified from Jones (2010a) Anderson/Canyon merged
Figures 175 Figure 123. Generic cost curve showing 12.8 billion short tons (BST) reserve estimate at $13.20 per ton for the Powder River Basin, Wyoming and Montana. $0 $10 $20 $40 $30 $50 $70 $60 Current market price, in cost per ton Total recoverable resources Cummulative tons reported in billions of short tons (BST) Reserve estimate at $18.00 per short ton 30 BST 60 BST Reserve estimate at $12.00 per short ton
176 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 124. Map showing areal extent for the composite stripping ratio of the Roland (Baker), Smith, Upper Anderson, Anderson, Dietz, and Canyon coal beds in the Gillette coal field, Wyoming Powder River Basin. T. 53 N. T. 52 N. T. 51 N. T. 50 N. T. 49 N. T. 48 N. T. 47 N. T. 45 N. T. 44 N. T. 43 N. T. 42 N. T. 41 N. T. 40 N. T. 39 N. R. 76 W. R. 75 W. R. 74 W. R. 73 W. R. 72 W. R. 71 W. R. 70 W. R. 69 W. R. 68 W. Buckskin Rawhide Eagle Butte Dry Fork Wyodak Caballo Belle Ayr Cordero Rojo Coal Creek Jacobs Ranch Black Thunder North Antelope/ Rochelle Antelope T. 46 N. 44°30' 44°00' 43°30' 105°45' 105°15' CONVERSE COUNTY CAMPBELL COUNTY WESTON COUNTY CAMPBELL COUNTY 20 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 20 MILES WYOMING MONTANA Powder River Basin Gillette coal field LOCATION MAP Stripping ratio EXPLANATION 3:1 1:1 Less than 1:1 2:1 4:1 5:1 6:1 7:1 8:1 9:1 10:1 1,000 feet depth to Canyon coal bed Mine area and identifier Gillette coal field boundary
Figures 177 Figure 125. Cost curve showing reserve estimates at $10.47 per short ton (as of January 2007) and $14.00 per short ton (as of March 2008) for the Gillette coal field, Wyoming. $0 $10 $20 $40 $30 $50 $70 $60 Current market price, in cost per ton Reserve estimate at $14.00 per short ton Reserve estimate at $10.47 per short ton Cummulative tons reported in billions of short tons (BST) 10.1 BST 18.5 BST Total recoverable resources (77,000 BTS)
178 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 126. Map showing areal extent for the composite stripping ratio of the Roland (Baker), Smith, Anderson, Dietz 3, Canyon, Lower Canyon, and Werner/Cook coal beds where the stripping ratios are from 1:1 to 10:1, thicknesses are equal to at least 5.0 feet, and the overburden is less than or equal to 500 feet thick, in the Wyoming Powder River Basin. MONTANA WYOMING MONTANA WYOMING CAMPBELL COUNTY CAMPBELL COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY JOHNSON COUNTY SHERIDAN COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY BIG HORN COUNTY BIG HORN COUNTY BIG HORN COUNTY Sheridan R. 55 E. R. 54 E. R. 53 E. R. 52 E. R. 51 E. R. 50 E. R. 49 E. R. 48 E. R. 45 E. R. 44 E. R. 42 E. R. 43 E. R. 41 E. R. 40 E. R. 39 E. R. 38 E. R. 37 E. R. 36 E. R. 35 E. R. 47 E. R. 46 E. T. 9 S. T. 57 N. T. 56 N. T. 55 N. T. 54 N. T. 53 N. T. 52 N. T. 51 N. T. 50 N. T. 8 S. R. 68 W. R. 69 W. R. 70 W. R. 71 W. R. 72 W. R. 73 W. R. 74 W. R. 75 W. R. 76 W. R. 77 W. R. 78 W. R. 79 W. R. 80 W. R. 81 W. R. 82 W. R. 83 W. R. 84 W. R. 85 W. R. 86 W. R. 87 W. 107°00' 106°00' 105°00' 45°30' 45°00' Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 25 KILOMETERS 25 MILES WYOMING MONTANA Powder River Basin LOCATION MAP Stripping ratio EXPLANATION 3:1 1:1 Less than 1:1 2:1 4:1 5:1 6:1 7:1 8:1 9:1 10:1 or greater Mine area Northern Wyoming Powder River Basin assessment area boundary Northern Wyoming Powder River Basin
Figures 179 Figure 127. Cost curve showing 1.5 billion ton reserve estimate at $9.30 per short ton (as of February 2010) for the Northern Wyoming Powder River Basin assessment area. $0 $5 $15 $10 $35 $30 $25 $20 Current market price, in cost per ton $9.30 Reserve Cummulative tons reported in billions of short tons (BST) Additional resource Recoverable resource
180 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 128. Map showing areal extent for the composite stripping ratio of the Roland (Baker), Smith, Anderson, Dietz 2, and Dietz 3 coal beds where the stripping ratios are from 1:1 to 10:1, thicknesses are equal to at least 5.0 feet, and the overburden is less than or equal to 500 feet thick, in the Montana Powder River Basin. Forsyth Colstrip Lame Deer Crow Agency Lodge Grass Miles City POWDER RIVER COUNTY CARTER COUNTY CUSTER COUNTY FALLON COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY R. 35 E. R. 36 E. R. 37 E. R. 38 E. R. 39 E. R. 40 E. R. 41 E. R. 42 E. R. 43 E. R. 44 E. R. 45 E. R. 46 E. R. 47 E. R. 48 E. R. 49 E. R. 50 E. R. 51 E. R. 52 E. R. 53 E. R. 54 E. R. 55 E. R. 56 E. R. 57 E. T. 6 N. T. 7 N. T. 8 N. T. 5 N. T. 4 N. T. 3 N. T. 2 N. T. 1 N. T. 1 S. T. 2 S. T. 3 S. T. 4 S. T. 5 S. T. 6 S. T. 7 S. T. 8 S. T. 9 S. 107°00' 106°00' 105°00' 45°30' 45°00' 46°00' Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 CUSTER NATIONAL FOREST 30 KILOMETERS 30 MILES WYOMING MONTANA Powder River Basin Montana Power River Basin LOCATION MAP Stripping ratio EXPLANATION 1:1 through 5:1 >5:1 through 10:1 Montana Powder River Basin assessment area boundary
Figures 181 Figure 129. Map showing areal extent for the stripping ratio of the Canyon coal bed where the stripping ratios are from 1:1 to 10:1, thicknesses are equal to at least 5.0 feet, and the overburden is less than or equal to 500 feet thick, in the Montana Powder River Basin. Forsyth Colstrip Lame Deer Crow Agency Lodge Grass Miles City POWDER RIVER COUNTY CARTER COUNTY CUSTER COUNTY FALLON COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY R. 35 E. R. 36 E. R. 37 E. R. 38 E. R. 39 E. R. 40 E. R. 41 E. R. 42 E. R. 43 E. R. 44 E. R. 45 E. R. 46 E. R. 47 E. R. 48 E. R. 49 E. R. 50 E. R. 51 E. R. 52 E. R. 53 E. R. 54 E. R. 55 E. R. 56 E. R. 57 E. T. 6 N. T. 7 N. T. 8 N. T. 5 N. T. 4 N. T. 3 N. T. 2 N. T. 1 N. T. 1 S. T. 2 S. T. 3 S. T. 4 S. T. 5 S. T. 6 S. T. 7 S. T. 8 S. T. 9 S. 107°00' 106°00' 105°00' 45°30' 45°00' 46°00' Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 CUSTER NATIONAL FOREST 30 KILOMETERS 30 MILES WYOMING MONTANA Powder River Basin Montana Power River Basin LOCATION MAP Stripping ratio EXPLANATION 1:1 through 5:1 >5:1 through 10:1 Montana Powder River Basin assessment area boundary
182 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 130. Map showing areal extent for the stripping ratio of the Werner/Cook coal bed where the stripping ratios are from 1:1 to 10:1, thicknesses are equal to at least 5.0 feet, and the overburden is less than or equal to 500 feet thick, in the Montana Powder River Basin. Forsyth Colstrip Lame Deer Crow Agency Lodge Grass Miles City POWDER RIVER COUNTY CARTER COUNTY CUSTER COUNTY FALLON COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY R. 35 E. R. 36 E. R. 37 E. R. 38 E. R. 39 E. R. 40 E. R. 41 E. R. 42 E. R. 43 E. R. 44 E. R. 45 E. R. 46 E. R. 47 E. R. 48 E. R. 49 E. R. 50 E. R. 51 E. R. 52 E. R. 53 E. R. 54 E. R. 55 E. R. 56 E. R. 57 E. T. 6 N. T. 7 N. T. 8 N. T. 5 N. T. 4 N. T. 3 N. T. 2 N. T. 1 N. T. 1 S. T. 2 S. T. 3 S. T. 4 S. T. 5 S. T. 6 S. T. 7 S. T. 8 S. T. 9 S. 107°00' 106°00' 105°00' 45°30' 45°00' 46°00' Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 CUSTER NATIONAL FOREST 30 KILOMETERS 30 MILES WYOMING MONTANA Powder River Basin Montana Power River Basin LOCATION MAP Stripping ratio EXPLANATION 1:1 through 5:1 >5:1 through 10:1 Montana Powder River Basin assessment area boundary
Figures 183 Figure 131. Map showing areal extent for the stripping ratio of the Pawnee coal bed where the stripping ratios are from 1:1 to 10:1, thicknesses are equal to at least 5.0 feet, and the overburden is less than or equal to 500 feet thick, in the Montana Powder River Basin. Forsyth Colstrip Lame Deer Crow Agency Lodge Grass Miles City POWDER RIVER COUNTY CARTER COUNTY CUSTER COUNTY FALLON COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY R. 35 E. R. 36 E. R. 37 E. R. 38 E. R. 39 E. R. 40 E. R. 41 E. R. 42 E. R. 43 E. R. 44 E. R. 45 E. R. 46 E. R. 47 E. R. 48 E. R. 49 E. R. 50 E. R. 51 E. R. 52 E. R. 53 E. R. 54 E. R. 55 E. R. 56 E. R. 57 E. T. 6 N. T. 7 N. T. 8 N. T. 5 N. T. 4 N. T. 3 N. T. 2 N. T. 1 N. T. 1 S. T. 2 S. T. 3 S. T. 4 S. T. 5 S. T. 6 S. T. 7 S. T. 8 S. T. 9 S. 107°00' 106°00' 105°00' 45°30' 45°00' 46°00' Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 CUSTER NATIONAL FOREST 30 KILOMETERS 30 MILES WYOMING MONTANA Powder River Basin Montana Power River Basin LOCATION MAP Stripping ratio EXPLANATION 1:1 through 5:1 >5:1 through 10:1 Montana Powder River Basin assessment area boundary
184 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 132. Map showing areal extent for the stripping ratio of the Rosebud/Knobloch coal bed where the stripping ratios are from 1:1 to 10:1, thicknesses are equal to at least 5.0 feet, and the overburden is less than or equal to 500 feet thick, in the Montana Powder River Basin. Forsyth Colstrip Lame Deer Crow Agency Lodge Grass Miles City POWDER RIVER COUNTY CARTER COUNTY CUSTER COUNTY FALLON COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY R. 35 E. R. 36 E. R. 37 E. R. 38 E. R. 39 E. R. 40 E. R. 41 E. R. 42 E. R. 43 E. R. 44 E. R. 45 E. R. 46 E. R. 47 E. R. 48 E. R. 49 E. R. 50 E. R. 51 E. R. 52 E. R. 53 E. R. 54 E. R. 55 E. R. 56 E. R. 57 E. T. 6 N. T. 7 N. T. 8 N. T. 5 N. T. 4 N. T. 3 N. T. 2 N. T. 1 N. T. 1 S. T. 2 S. T. 3 S. T. 4 S. T. 5 S. T. 6 S. T. 7 S. T. 8 S. T. 9 S. 107°00' 106°00' 105°00' 45°30' 45°00' 46°00' Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 CUSTER NATIONAL FOREST 30 KILOMETERS 30 MILES WYOMING MONTANA Powder River Basin Montana Power River Basin LOCATION MAP Stripping ratio EXPLANATION 1:1 through 5:1 >5:1 through 10:1 Montana Powder River Basin assessment area boundary
Figures 185 Figure 133. Map showing areal extent for the stripping ratio of the Flowers-Goodale coal bed where the stripping ratios are from 1:1 to 10:1, thicknesses are equal to at least 5.0 feet, and the overburden is less than or equal to 500 feet thick, in the Montana Powder River Basin. Forsyth Colstrip Lame Deer Crow Agency Lodge Grass Miles City POWDER RIVER COUNTY CARTER COUNTY CUSTER COUNTY FALLON COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY R. 35 E. R. 36 E. R. 37 E. R. 38 E. R. 39 E. R. 40 E. R. 41 E. R. 42 E. R. 43 E. R. 44 E. R. 45 E. R. 46 E. R. 47 E. R. 48 E. R. 49 E. R. 50 E. R. 51 E. R. 52 E. R. 53 E. R. 54 E. R. 55 E. R. 56 E. R. 57 E. T. 6 N. T. 7 N. T. 8 N. T. 5 N. T. 4 N. T. 3 N. T. 2 N. T. 1 N. T. 1 S. T. 2 S. T. 3 S. T. 4 S. T. 5 S. T. 6 S. T. 7 S. T. 8 S. T. 9 S. 107°00' 106°00' 105°00' 45°30' 45°00' 46°00' Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 CUSTER NATIONAL FOREST 30 KILOMETERS 30 MILES WYOMING MONTANA Powder River Basin Montana Power River Basin LOCATION MAP Stripping ratio EXPLANATION 1:1 through 5:1 >5:1 through 10:1 Montana Powder River Basin assessment area boundary
186 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 134. Graph showing cost curve for the Montana Powder River Basin assessment area showing estimated recoverable coal resources compared to sales price per ton of coal. $0 $5 $15 $10 $35 $30 $25 $20 Current market price, in cost per ton Cummulative tons reported in billions of short tons (BST) Total recoverable resources $13.20 12.8 BST
Figures 187 Figure 135. Bar graph showing resource and reserve summary in the Powder River Basin, Wyoming and Montana. Powder River Basin 107°00' 106°00' 105°00' 46°00' 45°30' 45°00' 44°30' 44°00' 43°30' 43°00' 40 KILOMETERS Base modified from U.S. Geological Survey and other Federal digital data, various scales Universal Transverse Mercator, zone 13N North American Datum of 1983 40 MILES Miles City Douglas Moorcroft Forsyth Casper Total resources In-place resources Recoverable resources Reserves Total resources In-place resources Recoverable resources Reserves Total resources In-place resources Recoverable resources Reserves Total resources In-place resources Recoverable resources Reserves Total resources In-place resources Recoverable resources Reserves 1,070 Powder River Basin total (billions of short tons) Northern Wyoming Powder River Basin (billions of short tons) Southwestern Powder River Basin (billions of short tons) Montana Powder River Basin (billions of short tons) Gillette coal field (billions of short tons) Mine model beds Mine model beds No beds modeled Mine model beds Mine model beds Northern Wyoming Powder River Basin Southwestern Powder River Basin Gillette coal field Glenrock CONVERSE COUNTY TREASURE COUNTY POWDER RIVER COUNTY POWDER RIVER COUNTY CAMPBELL COUNTY CAMPBELL COUNTY CONVERSE COUNTY BIG HORN COUNTY CUSTER COUNTY FALLON COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY BIG HORN COUNTY TREASURE COUNTY ROSEBUD COUNTY ROSEBUD COUNTY CUSTER COUNTY FALLON COUNTY CARTER COUNTY CARTER COUNTY CROOK COUNTY WESTON COUNTY WASHAKIE COUNTY JOHNSON COUNTY SHERIDAN COUNTY BIG HORN COUNTY NIOBRARA COUNTY NATRONA COUNTY Montana Powder River Basin Birney Gillette Sheridan Buffalo Decker Colstrip Broadus Ashland Lame Deer Wright MONTANA WYOMING WYOMING MONTANA Powder River Basin LOCATION MAP
188 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Figure 136. Graph showing cumulative cost curve for the Powder River Basin, Wyoming and Montana (Gillette coal field, Northern Wyoming Powder River Basin, and Montana Powder River Basin assessment areas). $0 $40 $50 $30 $10 $20 $60 $70 Current market price, in cost per ton Cummulative tons reported in billions of short tons (BST) Total recoverable resources Platt's price on July 15, 2013 Powder River Basin coal at 8,800 British thermal units per pound Reserve estimate at $10.90 per short ton Reserve estimate at $15.15 per short ton Reserve estimate at $8.90 per short ton 23 BST 43 BST 10 BST
Tables
Tables 191 Table 1. 2012 and cumulative coal production from the Powder River Basin, Wyoming and Montana (reported in short tons). Area/location/ mine name Dates of operation Coal bed mined production Total production Colstrip area, Montana Absaloka Mine 1974-present Rosebud/Knobloch 12,714,064 2174,377,733 Big Sky Mine 1969-2004 Rosebud/Knobloch Not applicable 2104,210,898 Rosebud Mine 1924-present Rosebud/Knobloch 18,018,098 2429,523,899 Total 110,732,162 2708,112,530 Decker/Spring Creek area, Montana Decker Mine 1972-present Smith, Anderson, Dietz 3 12,758,248 2359,497,693 Spring Creek Mine 1979-present Smith, Anderson, Dietz 3 117,199,485 2282,958,133 Total 119,957,733 2642,455,826 Sheridan coalfield area, Wyoming Big Horn Mine 1944-2000 Dietz 1, Dietz 2, Dietz 3 Not applicable 347,000,000 Other mines 1944-2000 Dietz 1, Dietz 2, Dietz 3 Not applicable 353,000,000 Total 3100,000,000 Gillette coalfield mines, Wyoming Antelope 1993-present Anderson, Canyon 134,316,314 4502,990,481 Belle Ayr 1972-present Anderson, Canyon 124,227,846 4695,975,751 Black Thunder 1978-present Anderson, Canyon 193,082,919 41,630,468,969 Buckskin 1981-present Anderson, Canyon 118,058,827 4431,995,844 Caballo 1978-present Anderson, Canyon 116,841,183 4608,700,789 Clovis Point 1979-1988 Anderson, Canyon Not applicable 418,508,466 Coal Creek 1982-present Anderson, Canyon 17,564,231 4113,262,743 Codero Rojo (Codero Mine) 1976-present Anderson, Canyon 139,204,736 4823,471,485 Dry Fork 1990-present Anderson, Canyon 16,006,787 486,872,662 Eagle Butte 1978-present Anderson, Canyon 122,466,733 4583,877,198 Jacobs Ranch 1983-2009 Anderson, Canyon Not applicable 4666,047,642 North Antelope/Rochelle 1986-present Anderson, Canyon 1107,639,188 41,486,763,140 North Rochelle 1985-2004 Anderson, Canyon Not applicable 4302,549,491 Rawhide 1978-present Anderson, Canyon 114,721,376 4336,434,632 Wyodak 1974-present Anderson, Canyon 14,245,981 4125,189,396 Total 1388,376,121 48,377,108,689 Glenrock coalfield, Wyoming Dave Johnston Mine 1958-2000 Baker (Roland), Smith Not applicable 3104,000,000 Total 3104,000,000 Grand total 419,066,016 9,931,677,045 1Mine Safety and Health Administration (MSHA), Mine Yearly Production Information (www.msha.gov/drs/ASP/Mine). 2Department of Labor and Industry Safety and Health Bureau, State of Montana, P.O. Box 1728, Helena, MT, 59624. 3Wyoming Geological Survey, written commun., 2009. 4Keystone Coal Industry Manual, years (1969-2000) and Mine Safety and Health Administration (MSHA), Mine Yearly Production Information (www.msha.gov/drs/ASP/Mine Action).
192 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Table 2. Typical proximate analysis on an as-received basis of coal from mines in the Powder River Basin, Wyoming and Montana. Area/location/ mine name Owner Coal bed name Calorific value (British thermal unit per pound) Sulfur (percent) Ash (percent) Colstrip area, Montana Absaloka Mine1 Westmoreland Coal Co. Rosebud/Knobloch 8,750 Big Sky Mine2 Peabody Energy/abandoned Rosebud/Knobloch 8,750 Rosebud Mine1 Westmoreland Coal Co. Rosebud/Knobloch 8,750 Otter Creek area (Arch Arch Coal Inc. Rosebud/Knobloch 8,497 Decker/Spring Creek area, Montana Decker Mine1 Kiewit Mining Group (manager) Smith, Anderson, Dietz 3 9,450 Spring Creek Mine1 Cloud Peak Energy Smith, Anderson, Dietz 3 9,350 Sheridan coalfield area, Wyoming Big Horn Mine2 Kiewit Mining Group/abandoned Dietz 1, Dietz 2, Dietz 3 9,300 Lake DeSmet area4 (estimated) Not applicable Lake DeSmet zone 7,559 Gillette coalfield area Wyoming Antelope1 Cloud Peak Energy Anderson, Canyon 8,800 Belle Ayr1 Alpha Natural Resources Anderson, Canyon 8,550 Black Thunder1 Arch Coal Anderson, Canyon 8,800 Buckskin1 Kiewit Mining Group Anderson, Canyon 8,400 Cabbalo1 Peabody Energy Anderson, Canyon 8,500 Clovis Point2 Kerr-McGee/abandoned Anderson, Canyon 8,050 Coal Creek1 Arch Coal Anderson, Canyon 8,325 Codero Rojo1 Cloud Peak Energy Anderson, Canyon 8,400 Dry Fork1 Western Fuels Anderson, Canyon 8,100 Eagle Butte1 Alpha Natural Resources Anderson, Canyon 8,400 Jacobs Ranch2 Arch Coal-combined/Black Thunder Anderson, Canyon 8,800 North Antelope/Rochelle1 Peabody Energy Anderson, Canyon 8,800 North Rochelle2 Triton Coal/abandoned Anderson, Canyon 8,673 Rawhide1 Peabody Energy Anderson, Canyon 8,300 Wyodak1 Wyodak Resources Anderson, Canyon 8,050 Glenrock coalfield, Wyoming Dave Johnston Mine2 Glenrock Coal Co./abandoned Baker (Roland), Smith 7,581 1Guide to Coal Mines, April 21, 2010. 2Keystone Coal Industry Manuals, 1998-2000. 3Minerals Management Service Memorandum July 22, 1982. 4Luppens, 2011.
Tables 193 Table 3. Typical proximate analysis on an as-received basis of coal beds reporting sodium as percent of ash, percent sulfur, percent ash, and calorific value, in coal beds in the Wyoming Powder River Basin compared to the Montana Powder River Basin. [All data from Guide to Coal Mines, April 21, 2010] Mine name and state Coal bed name Sodium, as percent of ash Sulfur (percent) Ash (percent) Calorific value (British thermal unit per pound) Wyoming Antelope Anderson, Canyon 8,800 Belle Ayr Anderson, Canyon 8,550 Black Thunder Anderson, Canyon 8,800 Buckskin Anderson, Canyon 8,400 Cabbalo Anderson, Canyon 8,500 Clovis Point Anderson, Canyon 8,050 Coal Creek Anderson, Canyon 8,325 Codero Rojo Anderson, Canyon 8,400 Dry Fork Anderson, Canyon 8,100 Eagle Butte Anderson, Canyon 8,400 North Antelope/Rochelle Anderson, Canyon 8,800 Rawhide Anderson, Canyon 8,300 Wyodak Anderson, Canyon 8,050 Montana Absaloka Rosebud/Knobloch 8,750 Decker Smith, Anderson, Dietz 3 1.00-8.00 9,450 Rosebud Rosebud/Knobloch 8,750 Spring Creek Smith, Anderson, Dietz 3 9,350
194 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Table 4. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by reliability category for the Powder River Basin, Wyoming and Montana. Reliability categories are based on distance from nearest data point. Measured: less than 0.25 mile; Indicated: 0.25-0.75 mile; Inferred: 0.75-3 miles; Hypothetical: greater than 3 miles. Totals may not sum exactly because of to rounding.—Continued Coal bed name Reliability category Original resources Burned coal Mined coal Remaining resources Land-use restrictions Technical restrictions Available resources Upper Healy Measured Indicated 2,212 2,129 1,885 Inferred 3,672 3,577 2,683 Hypothetical Total 6,863 6,657 5,327 Healy/ Lower Ulm Measured 1,677 1,673 1,539 Indicated 4,794 4,786 4,260 Inferred 6,320 6,306 1,119 4,900 Hypothetical Total 13,004 12,977 1,652 10,738 Murray Measured Indicated Inferred 1,144 1,144 Hypothetical Total 2,664 2,664 2,036 Ucross Measured Indicated 1,820 1,820 1,283 Inferred 4,115 4,115 2,761 Hypothetical Total 6,808 6,808 1,371 4,492 Upper Felix Measured 1,455 1,455 Indicated Inferred Hypothetical Total 2,122 2,122 1,205 Felix Measured 9,838 9,833 9,028 Indicated 6,801 6,798 6,123 Inferred 2,046 2,046 1,626 Hypothetical Total 18,759 18,750 1,246 16,784 Lower Felix Measured 4,376 4,375 3,196 Indicated 6,350 6,350 1,518 4,661 Inferred 8,100 8,100 6,700 Hypothetical Total 19,385 19,384 1,094 3,361 14,929 Roland Upper Rider Measured 4,257 4,257 1,632 2,560 Indicated 5,873 5,873 2,097 3,719 Inferred 3,353 3,353 1,286 2,008 Hypothetical Total 13,506 13,506 5,021 8,304 Roland Lower Rider Measured 1,014 1,014 Indicated 1,473 1,473 Inferred Hypothetical Total 3,257 3,257 1,555 1,693 Roland (Baker) Measured 14,647 14,646 1,171 12,947 Indicated 17,532 17,525 1,336 15,888 Inferred 15,475 15,472 14,460 Hypothetical Total 47,774 47,761 3,471 43,336 Roland (Taff) Measured Indicated 1,017 1,017 Inferred 1,574 1,574 1,161 Hypothetical Total 3,403 3,403 2,079 1,290 Upper Smith Measured Indicated Inferred Hypothetical Total 1,036 1,036
Tables 195 Table 4. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by reliability category for the Powder River Basin, Wyoming and Montana. Reliability categories are based on distance from nearest data point. Measured: less than 0.25 mile; Indicated: 0.25-0.75 mile; Inferred: 0.75-3 miles; Hypothetical: greater than 3 miles. Totals may not sum exactly because of to rounding.—Continued Coal bed name Reliability category Original resources Burned coal Mined coal Remaining resources Land-use restrictions Technical restrictions Available resources Smith Measured 45,930 45,924 45,297 Indicated 61,361 61,348 60,294 Inferred 18,821 18,810 1,243 17,144 Hypothetical Total 126,433 126,400 2,712 122,868 Anderson Upper Rider Measured Indicated Inferred Hypothetical Total Anderson Lower Rider Measured Indicated Inferred Hypothetical Total Anderson Measured 68,140 2,844 64,822 9,953 54,481 Indicated 43,040 1,502 40,692 3,656 1,053 35,983 Inferred 14,172 13,497 1,385 11,304 Hypothetical Total 125,481 1,879 4,484 119,118 14,446 2,847 101,825 Lower Anderson Measured Indicated 1,693 1,692 1,141 Inferred Hypothetical Total 3,382 3,380 1,340 2,039 Dietz 1 Measured Indicated Inferred Hypothetical Total 1,138 1,125 Dietz 2 Measured 1,222 1,172 Indicated 1,160 1,152 Inferred Hypothetical Total 2,992 2,928 2,032 Dietz 3 Measured 14,388 14,177 13,296 Indicated 23,975 23,754 1,068 22,125 Inferred 12,125 12,013 1,683 9,367 Hypothetical Total 50,880 50,329 1,998 3,268 45,063 Dietz 4 Measured Indicated Inferred Hypothetical Total 1,765 1,760 Upper Canyon/Cox Measured Indicated 2,182 2,180 1,784 Inferred 2,636 2,633 2,056 Hypothetical Total 5,968 5,961 1,168 4,711 Canyon Measured 48,817 48,102 2,079 45,737 Indicated 64,531 63,821 2,107 60,838 Inferred 32,607 32,311 2,988 1,397 27,925 Hypothetical 1,495 1,475 Total 147,450 145,708 7,535 2,719 135,454 Lower Canyon Measured 13,948 13,936 13,350 Indicated 27,319 27,273 1,305 25,153 Inferred 17,206 17,120 1,525 2,557 13,038 Hypothetical 1,056 1,036 Total 59,528 59,365 2,827 4,482 52,056
196 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Table 4. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by reliability category for the Powder River Basin, Wyoming and Montana. Reliability categories are based on distance from nearest data point. Measured: less than 0.25 mile; Indicated: 0.25-0.75 mile; Inferred: 0.75-3 miles; Hypothetical: greater than 3 miles. Totals may not sum exactly because of to rounding.—Continued Coal bed name Reliability category Original resources Burned coal Mined coal Remaining resources Land-use restrictions Technical restrictions Available resources Upper Ferry Measured Indicated Inferred Hypothetical Total Ferry Measured Indicated 1,866 1,866 1,472 1,257 Inferred 3,646 3,645 2,471 Hypothetical Total 6,396 6,394 1,774 4,277 Werner/Cook Measured 12,701 12,633 11,235 Indicated 31,534 31,296 1,668 1,487 28,141 Inferred 28,428 28,042 3,053 1,712 23,277 Hypothetical 1,323 1,308 Total 73,986 73,279 6,128 3,798 63,353 Upper Otter Measured Indicated Inferred Hypothetical Total Otter Measured 13,446 13,445 12,851 Indicated 33,479 33,472 1,666 31,601 Inferred 23,742 23,730 3,293 19,822 Hypothetical Total 71,021 71,000 5,781 64,310 Gates/Wall Measured 8,330 8,328 7,776 Indicated 25,828 25,809 1,868 23,481 Inferred 31,072 31,024 4,250 25,905 Hypothetical 1,196 1,195 Total 66,426 66,355 1,574 6,930 57,851 Pawnee Measured 2,105 2,098 1,761 Indicated 7,566 7,506 1,222 5,879 Inferred 13,842 13,689 1,928 2,984 8,777 Hypothetical Total 24,498 24,267 2,603 4,699 16,964 Brewster-Arnold Measured Indicated Inferred Hypothetical Total 1,968 1,892 Odell Measured 1,415 1,414 1,127 Indicated 3,872 3,870 1,237 2,540 Inferred 5,858 5,854 3,030 2,614 Hypothetical Total 11,676 11,668 4,765 6,581 Cache Measured Indicated Inferred 2,040 2,034 1,374 Hypothetical Total 3,303 3,286 2,013 A Zone Measured Indicated Inferred Hypothetical Total Upper Rosebud Measured Indicated Inferred Hypothetical Total
Tables 197 Table 4. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by reliability category for the Powder River Basin, Wyoming and Montana. Reliability categories are based on distance from nearest data point. Measured: less than 0.25 mile; Indicated: 0.25-0.75 mile; Inferred: 0.75-3 miles; Hypothetical: greater than 3 miles. Totals may not sum exactly because of to rounding.—Continued Coal bed name Reliability category Original resources Burned coal Mined coal Remaining resources Land-use restrictions Technical restrictions Available resources Rosebud/Knobloch Measured 7,021 6,442 5,297 Indicated 21,482 20,718 3,249 1,682 15,788 Inferred 34,764 34,203 6,202 2,912 25,088 Hypothetical 1,136 1,079 Total 64,401 1,452 62,442 10,279 5,072 47,091 Calvert Measured Indicated Inferred Hypothetical Total 1,161 1,160 McKay/Nance Measured 4,738 4,640 3,640 Indicated 12,689 12,664 2,692 9,088 Inferred 15,413 15,400 5,026 9,608 Hypothetical Total 33,289 33,146 2,024 8,509 22,614 Lower McKay Measured Indicated Inferred Hypothetical Total Flowers-Goodale Measured 5,647 5,645 4,672 Indicated 20,971 20,956 2,306 17,769 Inferred 32,716 32,686 4,407 27,589 Hypothetical 1,209 1,209 1,033 Total 60,544 60,496 1,986 7,447 51,064 Upper Witham Measured Indicated Inferred Hypothetical Total Robinson/Witham Measured 4,112 4,049 3,376 Indicated 8,259 8,209 1,251 6,167 Inferred 7,714 7,697 2,373 5,029 Hypothetical Total 20,677 20,547 1,479 4,061 15,007 Roberts/Terret Measured 3,453 3,450 2,994 Indicated 15,365 15,348 1,696 13,459 Inferred 31,487 31,448 4,450 26,860 Hypothetical 1,561 1,549 1,153 Total 51,866 51,795 6,930 44,467 Burley Measured Indicated Inferred 1,044 1,043 Hypothetical Total 1,632 1,631 Upper Stag Measured Indicated Inferred 1,239 1,239 Hypothetical Total 1,870 1,870 1,080 Lower Stag Measured Indicated Inferred Hypothetical Total Total beds Measured 301,189 1,126 4,120 295,948 17,827 14,232 263,883 Indicated 463,304 2,744 1,954 458,609 18,056 36,262 405,215 Inferred 381,662 2,389 379,037 25,548 56,915 296,620 Hypothetical 15,688 15,480 2,668 3,775 9,032 Total 1,161,850 6,468 6,306 1,149,072 64,097 110,211 974,752
198 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Table 5. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by overburden depth for the Powder River Basin, Wyoming and Montana. Resource includes coal plus partings. Totals may not sum exactly because of rounding.—Continued Coal bed name Overburden thickness (feet) Original resources Burned coal Mined coal Remaining resources Land-use restrictions Technical restrictions Available resources Upper Healy 0-500 6,681 6,475 5,225 500-1,000 1,000-2,000 2,000-3,000 Greater than 3,000 Total 6,863 6,657 5,327 Healy/Lower Ulm 0-500 11,228 11,202 1,334 9,355 500-1,000 1,774 1,774 1,381 1,000-2,000 2,000-3,000 Greater than 3,000 Total 13,004 12,977 1,652 10,738 Murray 0-500 1,681 1,681 1,292 500-1,000 1,000-2,000 2,000-3,000 Greater than 3,000 Total 2,664 2,664 2,036 Ucross 0-500 1,187 1,187 500-1,000 5,195 5,195 3,749 1,000-2,000 2,000-3,000 Greater than 3,000 Total 6,808 6,808 1,371 4,492 Upper Felix 0-500 2,033 2,033 1,147 500-1,000 1,000-2,000 2,000-3,000 Greater than 3,000 Total 2,122 2,122 1,205 Felix 0-500 15,881 15,872 14,270 500-1,000 2,803 2,803 2,456 1,000-2,000 2,000-3,000 Greater than 3,000 Total 18,759 18,750 1,246 16,784 Lower Felix 0-500 5,777 5,776 2,004 3,460 500-1,000 10,393 10,393 1,247 8,658 1,000-2,000 3,215 3,215 2,811 2,000-3,000 Greater than 3,000 Total 19,385 19,384 1,094 3,361 14,929 Roland Upper Rider 0-500 4,115 4,115 1,462 2,502 500-1,000 6,956 6,956 2,357 4,591 1,000-2,000 2,434 2,434 1,202 1,210 2,000-3,000 Greater than 3,000 Total 13,506 13,506 5,021 8,304 Roland Lower Rider 0-500 500-1,000 1,960 1,960 1,000-2,000 2,000-3,000 Greater than 3,000 Total 3,257 3,257 1,555 1,693
Tables 199 Table 5. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by overburden depth for the Powder River Basin, Wyoming and Montana. Resource includes coal plus partings. Totals may not sum exactly because of rounding.—Continued Coal bed name Overburden thickness (feet) Original resources Burned coal Mined coal Remaining resources Land-use restrictions Technical restrictions Available resources Roland (Baker) 0-500 16,907 16,894 1,108 14,990 500-1,000 17,993 17,993 1,274 16,625 1,000-2,000 12,848 12,848 1,089 11,695 2,000-3,000 Greater than 3,000 Total 47,774 47,761 3,471 43,336 Roland (Taff) 0-500 1,445 1,445 500-1,000 1,000-2,000 1,018 1,018 2,000-3,000 Greater than 3,000 Total 3,403 3,403 2,079 1,290 Upper Smith 0-500 500-1,000 1,000-2,000 2,000-3,000 Greater than 3,000 Total 1,036 1,036 Smith 0-500 6,583 6,550 5,400 500-1,000 41,135 41,135 40,094 1,000-2,000 78,389 78,389 77,053 2,000-3,000 Greater than 3,000 Total 126,433 126,400 2,712 122,868 Anderson Upper Rider 0-500 500-1,000 1,000-2,000 2,000-3,000 Greater than 3,000 Total Anderson Lower Rider 0-500 500-1,000 1,000-2,000 2,000-3,000 Greater than 3,000 Total Anderson 0-500 58,607 1,879 4,046 52,683 10,817 41,046 500-1,000 47,442 47,186 3,301 43,066 1,000-2,000 19,152 19,011 17,531 2,000-3,000 Greater than 3,000 Total 125,481 1,879 4,484 119,118 14,446 2,847 101,825 Lower Anderson 0-500 1,147 1,145 500-1,000 1,640 1,640 1,041 1,000-2,000 2,000-3,000 Greater than 3,000 Total 3,382 3,380 1,340 2,039 Dietz 1 0-500 500-1,000 1,000-2,000 2,000-3,000 Greater than 3,000 Total 1,138 1,125
200 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Table 5. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by overburden depth for the Powder River Basin, Wyoming and Montana. Resource includes coal plus partings. Totals may not sum exactly because of rounding.—Continued Coal bed name Overburden thickness (feet) Original resources Burned coal Mined coal Remaining resources Land-use restrictions Technical restrictions Available resources Dietz 2 0-500 1,677 1,612 1,153 500-1,000 1,000-2,000 2,000-3,000 Greater than 3,000 Total 2,992 2,928 2,032 Dietz 3 0-500 15,437 14,887 1,636 12,287 500-1,000 16,330 16,329 15,532 1,000-2,000 18,558 18,558 1,427 16,844 2,000-3,000 Greater than 3,000 Total 50,880 50,329 1,998 3,268 45,063 Dietz 4 0-500 500-1,000 1,000-2,000 2,000-3,000 Greater than 3,000 Total 1,765 1,760 Upper Canyon/Cox 0-500 500-1,000 1,000-2,000 4,226 4,226 3,766 2,000-3,000 1,055 1,055 Greater than 3,000 Total 5,968 5,961 1,168 4,711 Canyon 0-500 34,020 32,307 5,710 25,947 500-1,000 24,725 24,701 23,452 1,000-2,000 76,241 76,235 1,088 74,722 2,000-3,000 12,459 12,458 11,328 Greater than 3,000 Total 147,450 145,7 7,535 2,719 135,454 Lower Canyon 0-500 10,111 9,951 2,434 1,133 6,384 500-1,000 8,709 8,706 7,747 1,000-2,000 35,317 35,317 1,072 33,981 2,000-3,000 5,371 5,371 1,340 3,941 Greater than 3,000 Total 59,528 59,365 2,827 4,482 52,056 Upper Ferry 0-500 500-1,000 1,000-2,000 2,000-3,000 Greater than 3,000 Total Ferry 0-500 1,449 1,446 500-1,000 1,568 1,568 1,202 1,000-2,000 1,197 1,197 2,000-3,000 2,182 2,182 1,764 Greater than 3,000 Total 6,396 6,394 1,774 4,277 Werner/Cook 0-500 22,968 22,261 4,888 16,549 500-1,000 23,553 23,553 22,406 1,000-2,000 18,304 18,304 1,929 16,181 2,000-3,000 8,710 8,710 7,818 Greater than 3,000 Total 73,986 73,279 6,128 3,798 63,353
Tables 201 Table 5. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by overburden depth for the Powder River Basin, Wyoming and Montana. Resource includes coal plus partings. Totals may not sum exactly because of rounding.—Continued Coal bed name Overburden thickness (feet) Original resources Burned coal Mined coal Remaining resources Land-use restrictions Technical restrictions Available resources Upper Otter 0-500 500-1,000 1,000-2,000 2,000-3,000 Greater than 3,000 Total Otter 0-500 5,503 5,482 1,100 3,518 500-1,000 10,143 10,143 1,649 8,465 1,000-2,000 38,786 38,786 1,600 37,182 2,000-3,000 16,297 16,297 1,212 15,075 Greater than 3,000 Total 71,021 71,000 5,781 64,310 Gates/Wall 0-500 6,441 6,371 1,039 4,473 500-1,000 10,771 10,771 1,552 9,187 1,000-2,000 26,324 26,324 2,248 23,647 2,000-3,000 2,008 18,512 Greater than 3,000 2,240 2,240 2,032 Total 66,426 66,355 1,574 6,930 57,851 Pawnee 0-500 9,110 8,878 2,562 5,743 500-1,000 5,215 5,215 1,139 4,068 1,000-2,000 5,704 5,704 1,512 4,170 2,000-3,000 2,920 2,920 1,262 1,652 Greater than 3,000 1,549 1,549 1,331 Total 24,498 24,267 2,603 4,699 16,964 Brewster-Arnold 0-500 1,490 1,415 500-1,000 1,000-2,000 2,000-3,000 Greater than 3,000 Total 1,968 1,892 Odell 0-500 2,870 2,862 1,181 1,363 500-1,000 2,352 2,352 1,801 1,000-2,000 1,684 1,684 1,129 2,000-3,000 3,646 3,646 1,193 2,449 Greater than 3,000 1,124 1,124 Total 11,676 11,668 4,765 6,581 Cache 0-500 1,927 1,910 500-1,000 1,198 1,198 1,000-2,000 2,000-3,000 Greater than 3,000 Total 3,303 3,286 2,013 A Zone 0-500 500-1,000 1,000-2,000 2,000-3,000 Greater than 3,000 Total Upper Rosebud 0-500 500-1,000 1,000-2,000 2,000-3,000 Greater than 3,000 Total
202 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Table 5. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by overburden depth for the Powder River Basin, Wyoming and Montana. Resource includes coal plus partings. Totals may not sum exactly because of rounding.—Continued Coal bed name Overburden thickness (feet) Original resources Burned coal Mined coal Remaining resources Land-use restrictions Technical restrictions Available resources Rosebud/Knobloch 0-500 25,243 1,452 23,376 10,264 12,163 500-1,000 13,694 13,656 12,816 1,000-2,000 12,862 12,822 1,717 11,095 2,000-3,000 12,450 12,436 1,543 10,891 Greater than 3,000 Total 64,401 1,452 62,442 10,279 5,072 47,091 Calvert 0-500 500-1,000 1,000-2,000 2,000-3,000 Greater than 3,000 Total 1,161 1,160 McKay/Nance 0-500 7,669 7,541 1,130 1,506 4,904 500-1,000 6,175 6,167 1,686 4,277 1,000-2,000 10,476 10,471 2,706 7,087 2,000-3,000 8,449 8,447 2,366 6,069 Greater than 3,000 Total 33,289 33,146 2,024 8,509 22,614 Lower McKay 0-500 500-1,000 1,000-2,000 2,000-3,000 Greater than 3,000 Total Flowers-Goodale 0-500 8,937 8,889 1,298 6,742 500-1,000 10,832 10,832 1,374 9,358 1,000-2,000 27,593 27,593 2,747 23,851 2,000-3,000 12,303 12,303 1,788 10,472 Greater than 3,000 Total 60,544 60,496 1,986 7,447 51,064 Upper Witham 0-500 500-1,000 1,000-2,000 2,000-3,000 Greater than 3,000 Total Robinson/Witham 0-500 5,900 5,771 4,944 500-1,000 4,029 4,029 1,218 2,801 1,000-2,000 9,185 9,185 1,273 1,750 6,162 2,000-3,000 1,558 1,558 1,095 Greater than 3,000 Total 20,677 20,547 1,479 4,061 15,007 Roberts/Terret 0-500 4,733 4,662 1,307 3,222 500-1,000 3,436 3,436 1,279 2,157 1,000-2,000 18,718 18,718 2,084 16,537 2,000-3,000 17,459 17,459 1,815 15,479 Greater than 3,000 7,520 7,520 7,071 Total 51,866 51,795 6,930 44,467 Burley 0-500 500-1,000 1,000-2,000 2,000-3,000 Greater than 3,000 Total 1,632 1,631
Tables 203 Table 5. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by overburden depth for the Powder River Basin, Wyoming and Montana. Resource includes coal plus partings. Totals may not sum exactly because of rounding.—Continued Coal bed name Overburden thickness (feet) Original resources Burned coal Mined coal Remaining resources Land-use restrictions Technical restrictions Available resources Upper Stag 0-500 500-1,000 1,000-2,000 2,000-3,000 1,027 1,027 Greater than 3,000 Total 1,870 1,870 1,080 Lower Stag 0-500 500-1,000 1,000-2,000 2,000-3,000 Greater than 3,000 Total Total beds 0-500 304,254 6,467 5,712 292,073 49,000 30,633 212,439 500-1,000 286,536 286,201 7,444 27,718 251,042 1,000-2,000 428,340 428,141 6,012 31,597 389,863 2,000-3,000 107,387 107,327 1,481 17,543 109,015 Greater than 3,000 14,871 14,869 2,319 12,405 Total 1,161,850 6,468 6,306 1,149,072 64,097 110,211 974,752
204 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Table 6. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons, by coal ownership categories for the Powder River Basin, Wyoming and Montana. Resource includes coal plus partings. Totals may not sum exactly because of rounding.—Continued Coal bed name Coal ownership Original resources Burned coal Mined coal Remaining resources Land-use restrictions Technical restrictions Available resources Upper Healy Federal 4,277 4,131 3,661 State 1,105 1,058 Private 1,482 1,469 Total 6,863 6,657 5,327 Healy/Lower Ulm Federal 7,863 7,845 7,025 State 1,777 1,774 1,415 Private 3,363 3,358 2,298 Total 13,004 12,977 1,652 10,738 Murray Federal 1,777 1,777 1,385 State Private Total 2,664 2,664 2,036 Ucross Federal 3,457 3,457 2,369 State Private 2,402 2,402 1,573 Total 6,808 6,808 1,371 4,492 Upper Felix Federal 1,975 1,975 1,135 State Private Total 2,122 2,122 1,205 Felix Federal 17,357 17,349 1,118 15,559 State Private Total 18,759 18,750 1,246 16,784 Lower Felix Federal 13,690 13,689 2,945 10,366 State 2,362 2,362 2,033 Private 3,334 3,334 2,530 Total 19,385 19,384 1,094 3,361 14,929 Roland Upper Rider Federal 11,835 11,835 4,272 7,448 State Private Total 13,506 13,506 5,021 8,304 Roland Lower Rider Federal 2,871 2,871 1,398 1,465 State Private Total 3,257 3,257 1,555 1,693 Roland (Baker) Federal 39,324 39,311 2,827 35,764 State 4,049 4,049 3,796 Private 4,401 4,401 3,777 Total 47,774 47,761 3,471 43,336 Roland (Taff) Federal 2,623 2,623 1,610 1,009 State Private Total 3,403 3,403 2,079 1,290 Upper Smith Federal State Private Total 1,036 1,036 Smith Federal 110,339 110,307 2,090 107,947 State 7,242 7,242 6,978 Private 8,852 8,852 7,943 Total 126,433 126,400 2,712 122,868 Anderson Upper Rider Federal State Private Total
Tables 205 Table 6. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons, by coal ownership categories for the Powder River Basin, Wyoming and Montana. Resource includes coal plus partings. Totals may not sum exactly because of rounding.—Continued Coal bed name Coal ownership Original resources Burned coal Mined coal Remaining resources Land-use restrictions Technical restrictions Available resources Anderson Lower Rider Federal State Private Total Anderson Federal 111,597 1,691 4,112 105,793 12,706 2,244 90,844 State 7,624 7,373 6,457 Private 6,259 5,952 4,524 Total 125,481 1,879 4,484 119,118 14,446 2,847 101,825 Lower Anderson Federal 3,021 3,020 1,189 1,831 State Private Total 3,382 3,380 1,340 2,039 Dietz 1 Federal State Private Total 1,138 1,125 Dietz 2 Federal 2,561 2,510 1,776 State Private Total 2,992 2,928 2,032 Dietz 3 Federal 42,885 42,413 1,307 2,712 38,394 State 3,503 3,466 3,169 Private 4,493 4,450 3,500 Total 50,880 50,329 1,998 3,268 45,063 Dietz 4 Federal 1,228 1,224 State Private Total 1,765 1,760 Upper Canyon/Cox Federal 4,976 4,970 4,026 State Private Total 5,968 5,961 1,168 4,711 Canyon Federal 129,764 128,310 5,865 2,125 120,321 State 8,733 8,586 8,033 Private 8,954 8,811 1,336 7,100 Total 147,450 145,708 7,535 2,719 135,454 Lower Canyon Federal 50,659 50,528 2,211 3,515 44,801 State 4,027 4,012 3,561 Private 4,842 4,826 3,694 Total 59,528 59,365 2,827 4,482 52,056 Upper Ferry Federal State Private Total Ferry Federal 5,157 5,155 1,412 3,413 State Private Total 6,396 6,394 1,774 4,277 Werner/Cook Federal 64,995 64,342 5,435 3,253 55,653 State 4,487 4,466 4,021 Private 4,503 4,471 3,678 Total 73,986 73,279 6,128 3,798 63,353 Upper Otter Federal State Private Total
206 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Table 6. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons, by coal ownership categories for the Powder River Basin, Wyoming and Montana. Resource includes coal plus partings. Totals may not sum exactly because of rounding.—Continued Coal bed name Coal ownership Original resources Burned coal Mined coal Remaining resources Land-use restrictions Technical restrictions Available resources Otter Federal 63,828 63,808 4,849 58,097 State 4,167 4,167 3,728 Private 3,026 3,025 2,485 Total 71,021 71,000 5,781 64,310 Gates/Wall Federal 56,968 56,900 1,195 5,861 49,844 State 4,421 4,421 3,929 Private 5,037 5,037 4,078 Total 66,426 66,355 1,574 6,930 57,851 Pawnee Federal 21,156 20,948 2,504 3,939 14,505 State 1,564 1,560 1,191 Private 1,778 1,760 1,269 Total 24,498 24,267 2,603 4,699 16,964 Brewster-Arnold Federal 1,537 1,497 State Private Total 1,968 1,892 Odell Federal 10,013 10,007 3,983 5,712 State Private Total 11,676 11,668 4,765 6,581 Cache Federal 2,935 2,927 1,813 State Private Total 3,303 3,286 2,013 A Zone Federal State Private Total Upper Rosebud Federal State Private Total Rosebud/Knobloch Federal 51,662 50,786 8,947 4,395 37,444 State 2,435 2,335 1,966 Private 10,305 9,321 1,214 7,680 Total 64,401 1,452 62,442 10,279 5,072 47,091 Calvert Federal 1,021 1,020 State Private Total 1,161 1,160 McKay/Nance Federal 26,486 26,454 1,628 7,151 17,675 State 1,736 1,727 1,112 Private 5,066 4,965 3,827 Total 33,289 33,146 2,024 8,509 22,614 Lower McKay Federal State Private Total Flowers-Goodale Federal 51,020 50,995 1,453 6,187 43,356 State 2,984 2,980 2,410 Private 6,540 6,521 5,297 Total 60,544 60,496 1,986 7,447 51,064 Upper Witham Federal State Private Total
Tables 207 Table 6. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons, by coal ownership categories for the Powder River Basin, Wyoming and Montana. Resource includes coal plus partings. Totals may not sum exactly because of rounding.—Continued Coal bed name Coal ownership Original resources Burned coal Mined coal Remaining resources Land-use restrictions Technical restrictions Available resources Robinson/Witham Federal 14,606 14,590 1,332 3,366 9,892 State 1,008 1,002 Private 5,063 4,955 4,402 Total 20,677 20,547 1,479 4,061 15,007 Roberts/Terret Federal 43,088 43,055 5,616 37,146 State 2,876 2,875 2,501 Private 5,902 5,866 4,820 Total 51,866 51,795 6,930 44,467 Burley Federal 1,314 1,313 State Private Total 1,632 1,631 Upper Stag Federal 1,634 1,634 State Private Total 1,870 1,870 1,080 Lower Stag Federal State Private Total Total beds Federal 985,692 4,941 5,293 975,480 50,607 90,959 833,900 State 72,742 72,076 3,117 7,021 61,930 Private 103,415 1,203 101,523 10,372 12,195 78,922 Total 1,161,850 6,468 6,306 1,149,072 64,097 110,211 974,752
208 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Table 7. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by assessment area.—Continued [MTPRB. Montana Powder River Basin; NWPRB, Northern Wyoming Powder River Basin; SWPRB, Southwestern Powder River Basin; GILLETTE, Gillette coal field; East Gillette (area east of the Gillette coal field)] Coal bed name Assessment area name Original resources Burned coal Mined coal Remaining resources Land-use restrictions Technical restrictions Available resources Upper Healy MTPRB NWPRB 1,889 1,845 1,755 SWPRB 4,974 4,813 3,572 GILLETTE EAST GILLETTE Total 6,863 6,657 5,327 Healy/Lower Ulm MTPRB NWPRB 3,669 3,652 3,349 SWPRB 9,026 9,020 1,592 1,672 7,118 GILLETTE EAST GILLETTE Total 13,004 12,977 1,652 10,738 Murray MTPRB NWPRB SWPRB 1,718 1,718 1,356 GILLETTE EAST GILLETTE Total 2,664 2,664 2,036 Ucross MTPRB NWPRB 2,205 2,205 1,261 SWPRB 4,602 4,602 3,231 GILLETTE EAST GILLETTE Total 6,808 6,808 1,371 4,492 Upper Felix MTPRB NWPRB SWPRB GILLETTE 1,496 1,496 EAST GILLETTE Total 2,122 2,122 1,205 Felix MTPRB NWPRB 1,508 1,507 1,287 SWPRB 4,466 4,465 3,803 GILLETTE 12,786 12,777 11,695 EAST GILLETTE Total 18,759 18,750 1,246 16,784 Lower Felix MTPRB NWPRB 5,951 5,951 5,141 SWPRB 10,242 10,242 2,023 7,439 GILLETTE 3,189 3,188 2,347 EAST GILLETTE Total 19,385 19,384 1,094 3,361 14,929 Roland Upper Rider MTPRB NWPRB 4,799 4,799 1,480 3,225 SWPRB 6,681 6,681 2,609 4,016 GILLETTE 2,025 2,025 1,063 EAST GILLETTE Total 13,506 13,506 5,021 8,304 Roland Lower Rider MTPRB NWPRB SWPRB 2,284 2,284 1,464 GILLETTE EAST GILLETTE Total 3,257 3,257 1,555 1,693
Tables 209 Table 7. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by assessment area.—Continued [MTPRB. Montana Powder River Basin; NWPRB, Northern Wyoming Powder River Basin; SWPRB, Southwestern Powder River Basin; GILLETTE, Gillette coal field; East Gillette (area east of the Gillette coal field)] Coal bed name Assessment area name Original resources Burned coal Mined coal Remaining resources Land-use restrictions Technical restrictions Available resources Roland (Baker) MTPRB NWPRB 24,019 24,019 23,303 SWPRB 9,897 9,897 1,884 7,840 GILLETTE 13,130 13,130 1,099 11,555 EAST GILLETTE Total 47,774 47,761 3,471 43,336 Roland (Taff) MTPRB NWPRB 2,994 2,994 1,734 1,227 SWPRB GILLETTE EAST GILLETTE Total 3,403 3,403 2,079 1,290 Upper Smith MTPRB NWPRB SWPRB GILLETTE EAST GILLETTE Total 1,036 1,036 Smith MTPRB 1,869 1,840 1,627 NWPRB 10,273 10,273 1,229 8,919 SWPRB 87,868 87,866 86,501 GILLETTE 26,423 26,422 25,822 EAST GILLETTE Total 126,433 126,400 2,712 122,868 Anderson Upper Rider MTPRB NWPRB SWPRB GILLETTE EAST GILLETTE Total Anderson Lower Rider MTPRB NWPRB SWPRB GILLETTE EAST GILLETTE Total Anderson MTPRB 15,437 1,226 13,744 12,684 NWPRB 19,613 19,603 1,404 17,571 SWPRB 9,442 9,442 1,085 8,322 GILLETTE 79,909 3,986 75,636 12,654 62,733 EAST GILLETTE 1,080 Total 125,481 1,879 4,484 119,118 14,446 2,847 101,825 Lower Anderson MTPRB NWPRB 2,739 2,737 1,087 1,650 SWPRB GILLETTE EAST GILLETTE Total 3,382 3,380 1,340 2,039 Dietz 1 MTPRB NWPRB 1,017 1,011 SWPRB GILLETTE EAST GILLETTE Total 1,138 1,125
210 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Table 7. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by assessment area.—Continued [MTPRB. Montana Powder River Basin; NWPRB, Northern Wyoming Powder River Basin; SWPRB, Southwestern Powder River Basin; GILLETTE, Gillette coal field; East Gillette (area east of the Gillette coal field)] Coal bed name Assessment area name Original resources Burned coal Mined coal Remaining resources Land-use restrictions Technical restrictions Available resources Dietz 2 MTPRB 1,669 1,605 1,160 NWPRB 1,216 1,216 SWPRB GILLETTE EAST GILLETTE Total 2,992 2,928 2,032 Dietz 3 MTPRB 9,682 9,207 1,225 7,338 NWPRB 27,797 27,721 1,502 25,451 SWPRB 12,121 12,121 11,328 GILLETTE 1,279 1,278 EAST GILLETTE Total 50,880 50,329 1,998 3,268 45,063 Dietz 4 MTPRB NWPRB 1,042 1,040 SWPRB GILLETTE EAST GILLETTE Total 1,765 1,760 Upper Canyon/Cox MTPRB NWPRB SWPRB 5,269 5,269 4,590 GILLETTE EAST GILLETTE Total 5,968 5,961 1,168 4,711 Canyon MTPRB 18,999 18,691 3,388 14,996 NWPRB 26,874 26,656 1,346 24,332 SWPRB 65,913 65,913 64,823 GILLETTE 34,938 33,986 2,660 31,004 EAST GILLETTE Total 147,450 145,708 7,535 2,719 135,454 Lower Canyon MTPRB 10,200 10,096 2,165 1,183 6,748 NWPRB 19,080 19,020 2,078 16,370 SWPRB 29,410 29,410 1,166 28,155 GILLETTE EAST GILLETTE Total 59,528 59,365 2,827 4,482 52,056 Upper Ferry MTPRB NWPRB SWPRB GILLETTE EAST GILLETTE Total Ferry MTPRB 2,582 2,579 1,635 NWPRB 3,383 3,383 2,497 SWPRB GILLETTE EAST GILLETTE Total 6,396 6,394 1,774 4,277 Werner/Cook MTPRB 25,428 24,802 4,061 20,033 NWPRB 30,342 30,313 29,334 SWPRB 11,277 11,277 1,501 9,399 GILLETTE 6,627 6,615 1,544 4,423 EAST GILLETTE Total 73,986 73,279 6,128 3,798 63,353
Tables 211 Table 7. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by assessment area.—Continued [MTPRB. Montana Powder River Basin; NWPRB, Northern Wyoming Powder River Basin; SWPRB, Southwestern Powder River Basin; GILLETTE, Gillette coal field; East Gillette (area east of the Gillette coal field)] Coal bed name Assessment area name Original resources Burned coal Mined coal Remaining resources Land-use restrictions Technical restrictions Available resources Upper Otter MTPRB NWPRB SWPRB GILLETTE EAST GILLETTE Total Otter MTPRB 4,990 4,970 2,150 1,933 NWPRB 30,459 30,458 1,633 28,822 SWPRB 28,726 28,726 1,071 27,648 GILLETTE 6,759 6,759 5,894 EAST GILLETTE Total 71,021 71,000 5,781 64,310 Gates/Wall MTPRB 8,676 8,615 2,140 5,609 NWPRB 25,265 25,255 2,212 22,875 SWPRB 21,438 21,438 1,283 19,919 GILLETTE 10,975 10,975 1,226 9,444 EAST GILLETTE Total 66,426 66,355 1,574 6,930 57,851 Pawnee MTPRB 13,923 13,691 2,537 1,927 9,227 NWPRB 6,868 6,868 1,611 5,220 SWPRB 3,303 3,303 1,032 2,265 GILLETTE EAST GILLETTE Total 24,498 24,267 2,603 4,699 16,964 Brewster-Arnold MTPRB 1,852 1,777 NWPRB SWPRB GILLETTE EAST GILLETTE Total 1,968 1,892 Odell MTPRB 2,164 2,157 1,401 NWPRB 7,930 7,930 2,355 5,570 SWPRB 1,537 1,537 GILLETTE EAST GILLETTE Total 11,676 11,668 4,765 6,581 Cache MTPRB 3,217 3,200 1,939 NWPRB SWPRB GILLETTE EAST GILLETTE Total 3,303 3,286 2,013 A Zone MTPRB NWPRB SWPRB GILLETTE EAST GILLETTE Total Upper Rosebud MTPRB NWPRB SWPRB GILLETTE EAST GILLETTE Total
212 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Table 7. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by assessment area.—Continued [MTPRB. Montana Powder River Basin; NWPRB, Northern Wyoming Powder River Basin; SWPRB, Southwestern Powder River Basin; GILLETTE, Gillette coal field; East Gillette (area east of the Gillette coal field)] Coal bed name Assessment area name Original resources Burned coal Mined coal Remaining resources Land-use restrictions Technical restrictions Available resources Rosebud/Knobloch MTPRB 42,141 1,452 40,182 10,277 1,827 28,078 NWPRB 1,149 1,149 SWPRB 9,735 9,735 1,149 8,586 GILLETTE 10,847 10,847 1,019 9,827 EAST GILLETTE Total 64,401 1,452 62,442 10,279 5,072 47,091 Calvert MTPRB 1,161 1,160 NWPRB SWPRB GILLETTE EAST GILLETTE Total 1,161 1,160 McKay/Nance MTPRB 11,139 10,997 1,070 2,622 7,304 NWPRB 5,926 5,926 2,178 3,748 SWPRB 7,484 7,484 2,010 5,451 GILLETTE 7,642 7,642 1,223 5,562 EAST GILLETTE 1,097 1,097 Total 33,289 33,146 2,024 8,509 22,614 Lower McKay MTPRB NWPRB SWPRB GILLETTE EAST GILLETTE Total Flowers-Goodale MTPRB 26,066 26,018 2,465 22,626 NWPRB 2,347 2,347 1,045 1,302 SWPRB 14,259 14,259 1,958 12,301 GILLETTE 16,595 16,595 1,053 1,441 14,101 EAST GILLETTE 1,276 1,276 Total 60,544 60,496 1,986 7,447 51,064 Upper Witham MTPRB NWPRB SWPRB GILLETTE EAST GILLETTE Total Robinson/Witham MTPRB 10,864 10,735 2,696 7,994 NWPRB 2,110 2,110 1,454 SWPRB GILLETTE 6,780 6,780 1,391 4,892 EAST GILLETTE Total 20,677 20,547 1,479 4,061 15,007 Roberts/Terret MTPRB 11,467 11,396 3,199 8,067 NWPRB 16,274 16,274 1,050 15,220 SWPRB 11,373 11,373 1,351 10,018 GILLETTE 11,930 11,930 1,142 10,528 EAST GILLETTE Total 51,866 51,795 6,930 44,467 Burley MTPRB 1,606 1,605 NWPRB SWPRB GILLETTE EAST GILLETTE Total 1,632 1,631
Tables 213 Table 7. Coal resources and restrictions for 47 beds greater than or equal to 2.5 feet thick, reported in millions of short tons by assessment area.—Continued [MTPRB. Montana Powder River Basin; NWPRB, Northern Wyoming Powder River Basin; SWPRB, Southwestern Powder River Basin; GILLETTE, Gillette coal field; East Gillette (area east of the Gillette coal field)] Coal bed name Assessment area name Original resources Burned coal Mined coal Remaining resources Land-use restrictions Technical restrictions Available resources Upper Stag MTPRB NWPRB 1,084 1,084 SWPRB GILLETTE EAST GILLETTE Total 1,870 1,870 1,080 Lower Stag MTPRB NWPRB SWPRB GILLETTE EAST GILLETTE Total Total beds MTPRB 228,542 4,880 1,219 222,543 30,653 31,031 160,848 NWPRB 293,541 293,063 4,277 33,541 255,238 SWPRB 375,881 375,711 6,224 31,041 339,809 GILLETTE 256,632 4,871 251,294 22,500 13,892 214,899 EAST GILLETTE 7,153 6,462 2,063 3,956 Total 1,161,850 6,468 6,306 1,149,072 64,097 110,211 974,752
214 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Table 8. Summary of coal resources by reliability, depth, ownership, and assessment area categories in the Powder River Basin, Wyoming and Montana. [MTPRB. Montana Powder River Basin; NWPRB, Northern Wyoming Powder River Basin; SWPRB, Southwestern Powder River Basin; GILLETTE, Gillette coal field; East Gillette (area east of the Gillette coal field)] Coal bed name Reliability Original resources Burned coal Mined coal Remaining resources Land-use restrictions Technical restrictions Available resources Percent of available resources Coal resources and restrictions for 47 coal beds greater than or equal to 2.5 feet thick, reported in millions of short tons by reliability (see table 4) Total beds Measured 301,189 1,126 4,120 295,948 17,827 14,232 263,883 Indicated 463,304 2,744 1,954 458,609 18,056 36,262 405,215 Inferred 381,662 2,389 379,035 25,548 56,915 296,620 Hypothetical 15,688 15,480 2,668 3,775 9,032 Total 1,161,850 6,468 6,306 1,149,072 64,097 110,211 974,752 Coal bed name Overburden depth (feet) Original resources Burned coal Mined coal Remaining resources Land-use restrictions Technical restrictions Available resources Percent of available resources Coal resources and restrictions for 47 coal beds greater than or equal to 2.5 feet thick, reported in millions of short tons by overburden depth (see table 5) Total beds 0-500 304,254 6,467 5,712 292,073 49,000 30,633 212,439 500-1,000 286,536 286,201 7,444 27,718 251,042 1,000-2,000 428,340 428,141 6,012 31,597 389,863 2,000-3,000 107,387 107,327 1,481 17,543 109,015 14,871 14,869 2,319 12,405 Total 1,161,850 6,468 6,306 1,149,072 64,097 110,211 974,752 Coal bed name Ownership Original resources Burned coal Mined coal Remaining resources Land-use restrictions Technical restrictions Available resources Percent of available resources Coal resources and restrictions for 47 coal beds greater than or equal to 2.5 feet thick, reported in millions of short tons by ownership (see table 6) Total beds Federal 985,692 4,941 5,293 975,480 50,607 90,959 833,900 State 72,742 72,076 3,117 7,021 61,930 Private 103,415 1,203 101,523 10,372 12,195 78,922 Total 1,161,850 6,468 6,306 1,149,072 64,097 110,211 974,752 Coal bed name Assessment area Original resources Burned coal Mined coal Remaining resources Land-use restrictions Technical restrictions Available resource Percent of available resources Coal resources and restrictions for 47 coal beds greater than or equal to 2.5 feet thick, reported in millions of short tons by assessment area (see table 7) Total beds MTPRB 228,542 4,880 1,219 222,543 30,653 31,031 160,848 NWPRB 239,541 293,063 4,277 33,541 255,238 SWPRB 375,881 375,711 6,224 31,041 339,809 GILLETTE 256,632 4,871 251,294 22,500 13,892 214,899 EAST GILLETE 7,153 6,462 2,063 3,956 Total 1,161,850 6,468 6,306 1,149,072 64,097 110,211 974,752
Tables 215 Table 9. Summary of resources by reliability categories for all 47 coal beds assessed in the Powder River Basin and comparison of reliability of previous assessment of the Wyodak-Anderson zone in the Gillette coal field (Ellis and others, 1999) to the current Powder River Basin assessment. Reliability category Measured Indicated Inferred Hypothetical Total Reliability of 47 coal beds assessed in the Powder River Basin Tons (billions of short tons) 301,189 463,304 381,662 15,688 1,161,850 Percent of total Reliability of coal beds in the Wyodak-Anderson coal zone assessed in the Powder River Basin Powder River Basin Assessment Tons (billions of short tons) 206,945 255,974 128,258 4,875 596,052 Percent of total Ellis and others, 1999, Gillette coal field, Powder River Basin: Geology, coal quality, and coal resources, in U.S. Geological Survey Professional Paper 1625-A Tons (billions of short tons) 43,670 167,700 303,700 35,610 550,700 Percent of total Reliability of coal beds in the Wyodak-Anderson coal zone assessed in the Gillette coal field Powder River Basin Assessment Tons (billions of short tons) 94,433 51,950 10,769 157,366 Percent of total Ellis and others, 1999, Gillette coal field, Powder River Basin: Geology, coal quality, and coal resources, in U.S. Geological Survey Professional Paper 1625-A Tons (billions of short tons) 14,000 48,000 51,000 1,800 110,000 Percent of total Table 10. Example of a regional mine model stratigraphic sequence used in the economic evaluation of the Northern Wyoming Powder River Basin assessment area, River Wyoming. Coal bed name Interburden/overburden (feet) Stripping ratio 1:1 2:1 3:1 4:1 5:1 6:1 7:1 8:1 9:1 10:1 Bed 6 Average overburden thickness Average thickness Bed 5 Average overburden/interburden thickness Average thickness Bed 4 Average overburden/interburden thickness Average thickness Bed 3 Average overburden/interburden thickness Average thickness Bed 2 Average overburden/interburden thickness Average thickness Bed 1 Average overburden/interburden thickness Average thickness Total coal Total burden 1,055 1,172 Total interburden
216 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Table 11. Estimated impacts of compositing the originally excluded shale, pyrite, and other high-ash parting material with the coal analyses for the USGS-1 core hole (Luppens, 2011) from the Lake DeSmet coal area, Wyoming. Because these coal quality parameters are reported on a weight basis, mass weighting is the more appropriate method of mathematically compositing samples (Luppens and others, 1992). Lithologies Total core thickness (feet) Analytical parameters Volumetric weighting Mass weighting Ash
Calorific value (British thermal unit per pound) Volume (percent) Ash percent X volume (percent) Calorific value X volume percent (British thermal units per pound) Density (grams per cubic
Thickness X density Mass (percent) Ash percent X mass (percent) Calorific value X mass percent (British thermal units per pound) Shale excluded 1,500 Total coal analyzed 7,813 6,790 6,429 Total 6,986 6,694 1Ash and calorific values are the averages for USGS-1 core adjusted to 30.5 percent moisture and estimated values for the excluded shale. 2Density values are estimated. Table 12. Coal resources and reserves for beds greater than or equal to 5.0 feet thick in each assessment area in the Powder River Basin, Wyoming and Montana. (Reported in billions of short tons.) Resources/reserves East Gillette Gillette coal field Northern Wyoming Powder River Basin Southwestern Wyoming Powder River Basin Montana Powder River Basin Powder River Basin Original Resource for 47 beds 1,156 Resources East Gillette Gillette coal field Northern Wyoming Powder River Basin Southwestern Wyoming Powder River Basin Montana Powder River Basin Powder River Basin Roland (Baker), Smith, Anderson Upper Rider, Anderson, Dietz 3, Canyon Roland (Baker), Smith, Anderson, Dietz 3, Canyon, Lower Canyon, Werner Roland (Baker), Smith, Anderson, Dietz 2, Dietz 3, Canyon, Werner, Pawnee, Rosebud/Knobloch, Flowers-Goodale Roland (Baker), Smith, Anderson Upper Rider, Anderson, Dietz 2, Dietz 3, Canyon, Lower Canyon, Werner, Rosebud/Knobloch, Flowers-Goodale Original (listed beds) Remaining (listed beds) Available (listed beds) Recoverable (listed beds) Reserves
Tables 217 Table 13. Underground resources for coal beds 10-20 feet thick and greater than 500 feet deep in the Powder River Basin, Wyoming and Montana (reported in millions of short tons). Columns may not sum exactly because of rounding.—Continued Coal bed name Depth (feet) Northern Wyoming Powder River Basin Southwestern Powder River Basin Montana Powder River Basin Total short tons by bed Percent of total underground resource Roland (Baker) 500-1,000 6,254 6,254 500-1,500 4,187 4,187 1,000-2,000 9,308 9,308 1,500-2,000 Greater than 2,000 Total 15,672 4,345 20,017 Smith 500-1,000 500-1,500 75,957 75,957 1,000-2,000 3,447 3,447 1,500-2,000 5,945 5,945 Greater than 2,000 Total 4,346 81,902 86,248 Anderson 500-1,000 3,540 4,437 500-1,500 6,420 6,420 1,000-2,000 2,547 2,547 1,500-2,000 Greater than 2,000 Total 6,087 6,473 13,457 Dietz 3 500-1,000 5,610 6,364 500-1,500 8,303 8,303 1,000-2,000 5,322 5,328 1,500-2,000 1,980 1,980 Greater than 2,000 Total 10,972 10,283 22,015 Canyon 500-1,000 3,334 4,163 7,497 500-1,500 28,846 28,846 1,000-2,000 3,319 3,389 1,500-2,000 22,767 22,767 Greater than 2,000 Total 6,777 51,613 4,233 62,623 Lower Canyon 500-1,000 2,408 2,809 500-1,500 10,497 10,497 1,000-2,000 6,125 6,244 1,500-2,000 13,849 13,849 Greater than 2,000 Total 7,481 24,346 2,527 34,354 Werner/Cook 500-1,000 2,871 6,963 9,834 500-1,500 1,000-2,000 4,282 4,321 1,500-2,000 2,386 2,386 Greater than 2,000 3,204 3,204 Total 10,358 3,320 7,002 20,680 Otter 500-1,000 500-1,500 1,972 1,972 1,000-2,000 1,500-2,000 16,596 16,596 Greater than 2,000 Total 18,568 18,568 Pawnee 500-1,000 1,855 1,855 500-1,500 1,000-2,000 1,500-2,000 Greater than 2,000 Total 2,494 2,494
218 Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana Table 13. Underground resources for coal beds 10-20 feet thick and greater than 500 feet deep in the Powder River Basin, Wyoming and Montana (reported in millions of short tons). Columns may not sum exactly because of rounding.—Continued Coal bed name Depth (feet) Northern Wyoming Powder River Basin Southwestern Powder River Basin Montana Powder River Basin Total short tons by bed Percent of total underground resource Rosebud/Knobloch 500-1,000 10,271 10,271 500-1,500 1,000-2,000 1,251 1,251 1,500-2,000 Greater than 2,000 Total 11,522 11,522 Flowers-Goodale 500-1,000 6,468 6,468 500-1,500 1,000-2,000 5,854 5,854 1,500-2,000 Greater than 2,000 Total 12,325 12,325 Total 500-1,000 22,841 56,620 500-1,500 137,116 33,902 137,116 1,000-2,000 34,350 42,328 1,500-2,000 61,348 7,978 65,706 Greater than 2,000 4,497 41,880 4,500 Total 61,688 198,464 304,303 Percent of total underground resource by assessment area Publishing support provided by: Denver Publishing Service Center, Denver, Colorado For more information concerning this publication, contact: Center Director, USGS Central Energy Resources Science Center Box 25046, Mail Stop 939 Denver, CO 80225 (303) 236-1647 Or visit the Central Energy Resources Science Center Web site at: http://energy.usgs.gov/ This publication is available online at: http://dx.doi.org/10.3133/pp1809
ISSN 2330-7102 (online) ISSN 1044-9612 (print) http://dx.doi.org/10.3133/pp1809 Printed on recycled paper Luppens and others—Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana—Professional Paper 1809