Exploratory drilling program of the U.S. Geological Survey for evidences of zinc-lead mineralization in Iowa and Wisconsin, 1950-51

Agnew, Allen Francis, Flint, Arthur E., Allingham, John W. · 1953 · Report

The Upper Mississippi Valley zinc-lead district covers 2, 500 square miles of Wisconsin, Illinois, and Iowa. It is one of the oldest mining districts in the…

Public-domain full text preserved in the Mountain Man Mining Library. Original source: pubs.usgs.gov.

GEOLOGICAL SURVEY CIRCULAR 231 EXPLORATORY DRILLING PROGRAM OF THE U. S. GEOLOGICAL SURVEY FOR EVIDENCES OF ZINC-LEAD MINERALIZATION IN IOWA AND WISCONSIN, 1950-51

UNITED STATES DEPARTMENT OF THE INTERIOR Douglas McKay, Secretary GEOLOGICAL SURVEY W. E. Wrather, Director GEOLOGICAL SURVEY CIRCULAR 231 EXPLORATORY DRILLING PROGRAM OF THE U. S. GEOLOGICAL SURVEY FOR EVIDENCES OF ZINC-LEAD MINERALIZATION IN IOWA AND WISCONSIN, 1950-51 By Alien F. Agnew, Arthur E. Flint, and John W. Allingham Prepared in cooperation with the Wisconsin Geological and Natural History Survey Washington, D. C., 1963 Free on application to the Geological Survey, Washington 25, D. C.

EXPLORATORY DRILLING PROGRAM OF THE U. S. GEOLOGICAL SURVEY FOR EVIDENCES OF ZINC-LEAD MINERALIZATION IN IOWA AND WISCONSIN, 195051 By Alien F. Agnew, Arthur E. Flint, and John W. Allingham CONTENTS Page Abstract Introduction Purpose and scope of exploration History and mineral production of district.. Previous geologic work Acknowledgments General geology of the district The Tete des Morts area, Iowa Results of geologic mapping and exploratory drilling Stratigraphy ; Structure Evidence of mineralization Recommendations Page The Highland area, .Wisconsin 7 Stratigraphy , 9 Upper Cambrian 9 Lower Ordovician 9 Middle Ordovician 9 Results-of geologic mapping 9 Evidences of mineralization 9 Structure 10 Results of exploratory drilling 10 Recommendations 10 Literature cited 11 Generalized logs of drill-hole explorations 12 Tete des Morts area 12 Highland area 21 ILLUSTRATIONS Page Plate Map of the Tete des Morts area showing location of holes drilled by the U. S. Geological Survey In pocket Cross sections of holes drilled by the U. S. Geological Survey in the Tete des Morts area In pocket Map of Highland area showing location of holes drilled by the U. S. Geological Survey In pocket Cross sections of holes drilled by the U. S. Geological Survey in the Highland area In pocket Index map showing location of the Wisconsin-Illinois-Iowa zinc-lead mineralized district Map showing location of the Tete des Morts and Highland areas and the Black Jack-Bautsch trend Stratigraphic column of the Tete des Morts area Stratigraphic column of the .Highland area Figure 1. ABSTRACT The Upper Mississippi Valley zinc-lead district covers 2, 500 square miles of Wisconsin, Illinois, and Iowa. It is one of the oldest mining districts in the United States, as lead mining by settlers began in Zinc has been mined since 1859, and the present production is more than ten times that of lead. Rocks exposed in the district range from Early Ordovician to Middle Silurian in age, and, except for the St. Peter sandstone and the Maquoketa shale, consist mainly of dolomite. Structural compression has resulted in gentle folds and faults; principal trends are northwestward, northeastward, and eastward. Galena (lead sulfide) has been mined principally from vertical joints in the upper, noncherty part of the Galena dolomite. On the other hand, sphalerite (zinc sulfide) and a minor amount of smithsonite

(zinc carbonate) are found as veins, breccia ore, and disseminations in the lower, cherty part of the Galena dolomite, in strata of the Decorah formation, and in the upper beds of the Platteville formation; these "lower-run" ore bodies are in inclined reverse faults (pitches) and associated bedding-plane faults (flats) that are localized along synclinal trends. Lead and zinc minerals are found in beds of the Prairie du Chien group where they are exposed along the northern edge of the district. Since 1942 the U. S. Geological Survey has been studying the geology of the zinc-lead district and has been mapping the structure, stratigraphy, and the occurrences of ore bodies. The program here described was centered in two areas at the margin of the district. Twenty-five holes that totalled 7,466 feet were drilled in 1950-51. In the

Tete des Morts area, Iowa, the drilling showed lithology, structure, and evidences of mineralization that are favorable indications of the possible existence of pitch-type lower-run ore bodies; it showed a lateral extension of the potentially productive part of the district. In the Highland area, Wisconsin, lithology and evidences of mineralization found in strata of the Prairie du Chien group indicate that this unit might warrant further investigation as a potential source of ore at a lower stratigraphic position than that now being prospected in the main part of the zinc-lead district, farther south. Drilling in beds of the Prairie du Chien showed a vertical extension of the potentially productive part of the district. INTRODUCTION Purpose and scope of exploration The exploratory drilling program of the U. S. Geological Survey in Iowa and Wisconsin in 1950 and 1951 was part of a continuing comprehensive geologic investigation of the zinc-lead district (figs. 1 and 2) that began in 1942. The principal purpose of the drilling was to provide geologic data related to the over-all objective of extending laterally, (geographically) and vertically (stratigraphically) the favorable indications of and known potentialities for zinc and lead ore (Agnew and Heyl, 1947, p. 228.) The southern limit of current activity in the Wisconsin-Illinois-Iowa mining district is the Black Jack-Bautsch fold, an ore trend (fig. 2) a few miles south of Galena, 111. Because the currently mined ore bodies are large and rich and were discovered during recent years as a result of new geological ideas regarding the occurrence of ore, it was proposed to explore an area in Iowa, just to the west of the Black Jack-Bautsch mines. Answers to several geologic questions were sought: 1. Is the lighology of the Tete des Morts area similar to that in the Black Jack-Bautsch trend 5 miles to the east? 2. Are structural features (Willman and Reynolds, 1947, pp. 14-15) similar? 3. Are products of mineralization similar? Thus, the exploration in the Tete des Morts area was primarily an attempt to indicate a geographic, or lateral extension of the main ore-bearing zone of the zinc-lead district. Lead and zinc minerals in the Lower Ordovician Prairie du Chien group have been found in several localities, particularly in the northern part of the mining district (Heyl, Lyons, and Agnew, 1951 ). In the Highland area, surface indications of lead mineralization in the Prairie du Chien group are particularly abundant, and a deep shaft had been sunk in this area to mine lead ore. Furthermore, lead was in short supply when the Geological Survey program was being planned. The drilling in the Highland area, therefore, was an attempt to obtain information regarding the (1) stratigraphic occurrence, (2) structural relations, and (3) mineralogic relations of lead in the Prairie du Chien group. It was an attempt to extend vertically the zinc-lead district the search for a stratigraphically lower-producing zone. Preliminary geologic studies in the Tete des Morts and Highland areas were made in the summer of 1950 in order to choose the most promising localities for drilling. Five properties were selected, and 25 holes were drilled by cable-tool rigs between September 10, 1950, and May 25, 1951; the holes aggregated 7,466 feet of drilling. History and mineral production of district The zinc-lead district in Wisconsin, Illinois, and Iowa is one of the oldest mining areas in the United States. The lead mines in the Dubuque area were among the earliest worked by white men, beginning in 1788 with Dubuque's Concession. The annual production of lead increased rapidly in the late 1820's and reached a maximum of about 27,000 tons of lead metal in the middle 1840 's, when the district contributed 85 to 90 percent of the lead produced in the United States. Lead mining in this district declined gradually until 1878, when the annual output was less than 5,000 tons. Zinc production did not begin until 1859, as before that time no market existed. In 1859 zinc carbonate and in 1867 zinc sulfide were first mined, and by 1873 zinc sulfide had replaced' zinc carbonate as the district's major ore. By 1872 zinc production was about twice that of lead. The zinc-lead ratio increased only slightly until World War I when it suddenly became about 20 to 1 in 1917, and the peak of .zinc output from this district was more than 64,000 tons of zinc metal. By 1930 most of the large mining companies had left the district, and for the next 10 years zinc-lead production was generally low until the demands of World War II rejuvenated zinclead activity in 1941. Several large mining companies entered the district after 1944, and a large program of exploration and mining is now under way. Mines in the district produced about 1, 120,000 tons of zinc metal from 1859 to 1947 and about 815,000 tons of lead metal from 1800 to 1947. Previous geologic work The mining district was studied intermittently but rather thoroughly by government survey parties from 1836 until about 1916. From 1916 to the late 1920's the geologic investigations were carried out by company geologists. During the 1930's research by faculty and students of universities nearby kept geologic interest alive; however, except for the work of Behre (1939), these studies were directed toward specific phases of geology rather than general investigations of the entire district. Numerous publications resulted from the previous geologic work, but an adequate resume or bibliography is not within the scope of this brief report. Acknowledgments The Wisconsin Geological and Natural History Survey supplied part of the funds for the supervision of the drilling program. C. W. Tandy, Jr., aided by surveying during the preliminary geologic investigations of the two areas.

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GENERAL GEOLOGY OF THE DISTRICT Much of the bedrock in the Wisconsin-IlMnoislowa zinc-lead district is covered with a mantle of Pleistocene and Recent loess as much as 35 feet thick. The sedimentary rocks exposed in the district range from Early Ordovician to Middle Silurian in age. A generalized summary of the rocks, compiled from outcrop and drill-hole data, is as follows: Silurian system. Kankakee limestone of Savage (1916) Edgewood limestone Ordovician system. Maquoketa shale Prairie du Chien group Cambrian system. TYwo o"Ko fin TirScfh OTI& Dominant lithology j Dolomite, chert Shale, dolomite Dolomite, chert Limestone, dolomite, chert. Limestone, dolomite, shale. Sandstone Dolomite, chert, shale, sandstone. Dolomite, sandstone, siltstone. Sandstone, shale, siltstone. Sandstone, shale, siltstone. Average thickness (feet) 150-1105-200

The zinc-lead district lies on the south side of the Wisconsin pre-Cambrian high (Thwaites,and Howell, 1935); it is just west of the structural extension southward toward the LaSalle anticline in Illinois (Thwaites, Howell, and Jones, 1935). The strata of the district have been gently flexed and broken. Although the folds are of small amplitude and are generally local, general axial trends can be traced for several miles. These trends are northeastward and northwestward; eastward folds of similar continuity are less common. Faults are of relatively small magnitude and are of three general types reverse, normal, and tear. Dip-slip displacement on the reverse faults is less than 6 feet, but strikeslip displacement on the tear faults is known to be at least 35 feet and may be as much as 200 feet or more. Solution effects that accompanied the zinc-lead mineralization accentuated the tectonic structural features and altered the lithologic features of the rocks. Deposits of zinc-lead are found mainly in the lower part of the Galena dolomite ("drab" of local usage), the Decorah formation ("gray, " "blue, " "oil rock," and "clay bed" of local usage), and the upper part of the Platteville formation ("glass rock" and "Trenton" of local usage). Lead was recovered from vertical joint crevices in the upper, noncherty part of the Galena dolomite. The galena in these "upperrun" deposits occurred as isolated crystals (dice lead) or clusters (cog lead) in a matrix of dolomite sand, as veins (sheets) less than an inch thick, and as pods several feet wide. Podlike forms of ore were present in "openings" (Whitney, 1858, p. 438) at favorable stratigraphic horizons. At one or more of these horizons, similar podlike enlargements occurred at intervals along a crevice. At intersections of crevices, "chimneys" or pipes of galena were sometimes found. Individual crevices were mined for lengths as much as 1, 700 feet. In the lower, cherty part of the Galena dolomite, in beds.of the Decorah formation, and in the upper part of the Platteville formation zinc and some lead ore deposits were mined from reverse faults (pitches) and associated bedding-plane faults (flats) in the limbs of synclines. In one of these "lower-run" ore bodies the minerals replaced the rock and filled vugs, constituting a "brangle" (solution-breccia zones of dolomite blocks cemented by sphalerite and marcasitepyrite) type of ore in the "core ground," which lies on the footwall side of and extends to within a few. feet of the pitch. The ore bodies were as much as 30 feet or more high (in the Black Jack mine more than 120 feet), 100 feet or more wide, and 3, 500 feet or more long, although the average length was perhaps 1,000 feet. The Prairie du chien group constitutes a lower, potentially ore -bearing zone, as in a few places in the northern part of the district galena has been mined from dolomite beds in the upper part of the unit. THE TETE DES MORTS AREA, IOWA The Tete des Morts area is in southeasternDubuque County and northeastern Jackson County, Iowa (fig. 2). The area in which drilling was done is about 1 .square mile and is bounded on the northeast by the Mississippi River. Relief is about 160 feet, and the upland is under cultivation. Lead ore was mined in this area by the Indians, and its occurrence was briefly described by Owens (1840),

who stated that by 1839 at least 15,000 pounds of lead ore had been raised from H. H. Gher's diggings (pi. 1). The Tete des Morts diggings, however, have never been very productive and have long since been abandoned. Lead ore has been mined in recent years from shafts on Kohlenberg's land and from shafts a mile and a half southeast of Gordon's Ferry. Zinc minerals were reported in one of the shafts on the Kohlenberg farm. Before the drilling, exploration, which will be described, a reconnaissance survey of the structural geology was made by Agnew and Flint along the Mississippi River bluff and back from the River, up the tributary valleys. Two synclines were found, one northeastward and the other northwestward in trend (pi. 1). Steep dips, a shattered zone in the rocks, and iron minerals indicative of a pitch zone were seen at the southeast end of the meander intheTetedesMorts River in sec. 3. Joint strikes were mapped, and the pattern showed general northwestward, northeastward, and eastward trends. The lowest beds exposed in the Tete des Morts area are a few feet of cherty dolomite at the top of the lower, or cherty unit of the Galena dolomite. The upper, or noncherty beds of the Galena are seen along the bluffs of the Mississippi and Tete des Morts Rivers and provided most of the data fox1 mapping the geologic structure. The lower beds of the Maquoketa shale are exposed in the upper reaches of a few small ravines. Shafts and smaller pits, remnants of lead diggings that are as much as 100 years old, were also located by reconnaissance geologic mapping. The lithology of material on the dump indicated that the productive zone was stratigraphically above the top of the cherty unit of the Galena dolomite. Iron minerals in the exposure of the pitch zone along the Tete des Morts River ranged in stratigraphic position from a few feet below the top of the cherty beds upward for about 75 feet. Between September 10, 1950, and February 15, 1951, two properties in Iowa were drilled; the drilling totaled 13 holes and 4,036 feet. Cuttings were sacked for every 5 feet of drilling and were examined with a binocular microscope. (Summary logs are included on pp. 11-36.) Results of geologic mapping and exploratory drilling Stratigraphy. The St. Peter sandstone was penetrated in only one hole, Schenk 1, which cut through 18 feet of a quartz sandstone (fig. 3). A pyritecemented streak was found in the upper part of the unit; however, such streaks are common in the St. Peter in the upper Mississippi Valley district and have no known significance concerning the proximity of ore bodies. The Platteville formation is 64 feet thick in Schenk hole 1,. the only hole penetrating the base of this formation. In this hole the lower part of the Platteville formation consists of light-brown dolomite (Pecatonica dolomite member), overlying thin green shale (Glenwood shale member). The McGregor limestone member is a gray limestone in Schenk holes 1 to 3, which penetrated its entire thickness. The uppermost member of the Platteville, the Quimbys Mill member or "glass rock " of local usage, is limestone except in Kohlenberg hole 2, where part of the rock is dolomitic limestone. A trace of pyrite in the "glass rock" unit in Schenk hole 7 is the only indication that the rocks of the Platteville formation were mineralized. The Decorah formation, which averages 43 feet in thickness, consists of four units. The lowest, or Spechts Ferry shale member, is green shale; the middle, or Guttenberglimestone member, is brown limestone and shale, called "oil rock"; and the upper two, which constitute the Ion dolomite member, are gray and dark-gray limestone (dolomite in Schenk holes 4 through 9) and shale. In the Tete des Morts area the Galena dolomite, 225 feet thick, is dolomite throughout, except on the Kohlenberg property where the lower 25 to 30 feet contain as much as 90 percent limestone and dolomitic limestone. The lack of limestone, in the Galena dolomite on the Schenk property shows that the dolomite is due apparently to dolomitization associated with mineralization, for, if it were due to regional dolomitization, these beds on the Kohlenberg land would also have been dolomitized. Several "openings" occur in the Galena dolomite in the Dubuque, Iowa, area 15 miles to the northwest and in the Galena, 111., area 5 miles northeast of the Tete des Morts area; the stratigraphic positions of these openings are shown in figure 3. Galena is the common mineral in the openings, but in the Dubuque area sphalerite and marcasite-pyrite are reported from openings that lie below the water table. The openings in the upper, noncherty unit of the Galena dolomite are commonly filled with clay and dolomite sand. However, the "upper flint" opening, the "lower flint" opening, and the mineralized zone (here named the lower Receptaculites opening) that lies 20 to 30 feet above the base of the Galena dolomite are commonly brangle zones. Even though it has great length, the opening type of deposit is relatively narrow, and prospecting for this type of ore zone by vertical drilling is likely to be disappointing. No Maquoketa shale was penetrated in the holes drilled. In Schenk hole 5, however, phosphatic pebbles similar to the material of the depauperate zone occurring at the base of the Maquoketa shale were found below the surficial material; so the basal contact of the Maquoketa was probably within a few feet of the depth at which it was logged. Lithologic information for the Maquoketa (fig. 3) was derived mainly from the study of samples from a well drilled .about 2 miles to the south (W. H. Felderman, wiNEiSEi sec. 15, T. 87 N., R. 4E., Iowa). A capping of loess as much as 35 feet thick is present on the uplands. Structure. One of the major reasons for the selection of the Tete des Morts area was the occurrence of favorable structures.

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Dolomite, as above Bentonite PIPE-CLAY OPENING Dolomite, as above; bands of chert nodules ] UPPER FLINT OPENING Dolomite, as above; less cherty LOWER FLINT OPENING Dolomite, as above; cherty "] 've j-

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Dolomite, as above; very cherty Dolomite, as above; no chert Dolomite and limestone, light-gray, medium-crystalline, gray+specked; fossitiferous greenish gray calcareous shale

Limestone, buff to brown, fine-groined, dense, calcareous, red-specked.; , shale, dark brown Shofe, green, soft; limestone, greenish-gray fine-grained dense; phosphatic nodules Limestone, brownish, medium-granular., sugary; shale, dark-brown

Limestone, gray, fine-to medium-crystalline, fossil If erous, argillaceous; trace gray shale Dolomite, brown, medium-granular, black specks; phosphate nodules at base, sandy at base \Shale, grayish-green; sand, quartz, subrounded. coarse, write cement Sand, quartz, subrounded, fine to very coarse, poorly cemented 70+ Tcf O N If) O i y 18+ in CM CM to

gb Figure 3. Stratigraphic column of the Tete des Morts area, Dubuque and Jackson Counties, Iowa.

A structure contour map (pi. 1) of the top of the cherty unit of the Galena dolomite,prepared before drilling,showed two synclines that appeared to join near the center of the wi? of sec. 3. Drilling corroborated the presence of both synclines. The northeastward-trending syncline is thought to be the extension of the Galena-Shullsburg syncline and has much more relief than the narrower northwestward-trending one, which is like the Black Jack-Bautsch fold. Evidence of mineralization Indications of solution-thinning of the "oil rock" (middle part of Decorah formation) and the "glass rock" (upper part of Platteville formation) were seen in cuttings from one of the holeS( (Schenk 4), drilled near the pitch zone noted previously. Although lines of lead shafts and "sucker holes" (diggings) were found, they are thought to be related to mining of the vertical or near-vertical "upper-run" (in the noncherty unit of the Galena dolomite) or crevice deposits and were not given any weight in the planning of the drilling because the purpose of this program was to explore the "lower-run" or pitch-and-flat type of ore body. Holes 1 through 6 on the Schenk property (sec. 3) were spotted, on 125-foot centers, to cut across the southeastern projection of the pitch zone in the Tete des Morts River. They were drilled on the northeast limb of the northwestward-trending structure. Iron minerals were the only significant evidence of mineralization in Schenk holes 1 through 6. Holes 2, 3, and 5 showed an estimated 3. 5 to 4. 7 percent iron for a thickness of 16 to 39 feet (pi. 2); all the holes except no. 4 had traces of zinc, and hole 3 had a trace of lead. The iron minerals were found at the stratigraphic position of the upper and lower flint openings. As this position is in the upper part of the pitch-type ore bodies farther north and east, the occurrence of the iron is interpreted as a favorable indication of the possible existence of pitch-type lower-run ore bodies in the Tete des Morts area. Although no pitch-type fractures were found in the drilling, the existence of solution-thinning of the "oil rock" and "glass rock" with associated concentration of shaly material found in Schenk hole 4 is believed to justify further exploration for lower-run zinc-lead deposits. Holes 7 through 9 on the Schenk property were alined across the gently dipping southeast limb of the northeastward-trending syncline. In hole 7, iron deposition similar to that in holes 2, 3, and 5 was discovered at the same stratigraphic position as in holes 1 through 6. In addition, a mineral identified as one of the manganese oxides was present at this position of the upper flint opening. This cross section, holes 7 through 9, showed less promise than the one for holes 1-6. The alinement of holes drilled on Kohlenberg's property crossed the northwestward-trending syncline. Hole 1 showed iron deposition estimated at 3 percent for 15 feet at the position of the lower Receptaculites opening, which is near the base of the Galena dolomite. Hole 2 showed traces of zinc, and hole 4 showed the manganese mineral, noted in Schenk hole 7, in the "gray" beds of the Decorah formation. The significance of the manganese mineral is not known; however, the iron in Kohlenberg hole 1 is interpreted as a favorable indication of the possible existence of pitch-type lower-run ore bodies in the Tete des Morts area. All holes drilled in the Tete des Morts area were completed to the desired depth at or near the base of the "glass rock" except Kohlenberg hole 1, which was bottomed in the "gray" beds of the Decorah. In the lower part of this hole, from 215 to its total depth of 244 feet, a joint with a strong flow of water caused such drilling and sampling difficulties that the hole was abandoned. Recommendations The exploratory work here described showed structure, lithology, and type and position of mineralized zones that are interpreted as favorable indications of the possible existence of pitch-type lower-run ore bodies. The Tete des Morts and surrounding area thus constitute a potential extension of the mining district and further exploratory work is recommended. Outcrop mapping is recommended as a means of locating geologic structures along the Mississippi River bluff, the Tete des Morts River, and other areas where exposures are numerous and structural control is good. Where such geologic data are not available, it is recommended that favorable structure be prospected for by means of drilling, .preferably using either a grid, or a series of cross sections across syncline trends. Although the ore bodies are localized along structural trends, not all such trends bear ore bodies, and any one trend can have both ore-bearing and lean or blank areas. Thus, the structural picture must be used only as a guide in finding ore, not as a certain indication of ore. Furthermore, it is recommended that any exploratory program, in this or similar new areas in the district, be planned to include an adequate number of drill holes. Recent experience by mining companies in the district has shown that limited drilling can give only insufficient information regarding any ore discoveries and often it unjustly condemns an area. THE HIGHLAND AREA, WISCONSIN The Highland area (fig. 2) in west-central Iowa County and the adjoining part of Grant County, Wis., includes about 5 square miles. The village of Highland lies in the northeast corner of the area. Maximum topographic relief is approximately 300 feet. The uplands are under cultivation; the valley slopes and narrow stream flood plains are grasslands. Zinc and lead ores in this area have been mined from Middle Ordovician rocks of the Platteville,Decorah, and Galena formations and lead ore has been taken from Lower Ordovician rocks of the Prairie du Chien group. The formations that contain these two orebearing zones are separated by the Middle Ordovician St. Peter sandstone (fig. 4). Because this part of the exploration by the Geological Survey was concerned with the lower ore zone, evidence of mineralization

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in the Prairie du Chien rocks only is discussed. Most of the lead ore from this unit was mined from about 1850 to 1880, and no records of production are available. Areas of diggings (pi. 3) are relatively extensive, more so in the Highland vicinity than in other places where ore has been mined from the Prairie du Chien strata. The Ohlerking mine, near the center of the WiSEisec. 31, T. 7N., R. IE., produced only lead ore. It was operated through a shaft about 180 feet deep, from which about 275 feet of drift was driven (Chamberlin, 1882, pp. 516-517). Although the amount of lead ore recovered is not known, this was the largest operation in the lower ore,zone. A preliminary survey of the geology of the area, including the examination of the old mine dumps, was made by Flint before drilling was begun. A geologic and structural map (pi. 3) based on information gathered during this survey was used for determining the location of the drill holes. The topography was the only other important factor governing the exact location of the holes. Stratigraphy Upper Cambrian. The Upper Cambrian Trempealeau formation is not exposed in the area mapped in the vicinity of Highland but crops out 3 miles north. The upper Trempealeau strata are sandstone. They consist of white fine and medium subangular to surround quartz grains. Green shale partings separate the irregular thin sandstone beds. Lower Ordovician. The Lower Ordovician Prairie du Chien group, which includes the mineralized zones explored by drilling, conformably overlies the Upper Cambrian Trempealeau formation and crops out in the northern half of the Wisconsin-Illinois-Iowa mining district in the more deeply dissected stream valleys. Where observed in the Highland area,this group is from 50 to 215 feet thick. Farther west a middle sandstone unit separates the dolomite strata of the group and permits its division into three formations. An attempt was made to extend this threefold division into the area covered by this report; however, because of incomplete knowledge of detailed Prairie du Chien stratigraphy throughout the mining district, it was not possible to identify positively the middle formation (fig. 4 and pi. 4), if it is present in the Highland area. From the base upward the three formations have been called the Oneota dolomite", New Richmond sandstone, and Shakopee .dolomite. Recent study by-Flint, however, has shown that these members are nor mappable units either in the Highland area or generally in the Wisconsin-Illinois-Iowa zinc-lead district. The Oneota dolomite is mainly a brown-gray medium-grained crystalline dolomite. Chert is common to abundant 30 to 40 feet above the base and in the upper half of the member. Oolitic textures appear near the base in both the chert and dolomite. Glauconite is common as a minor constituent of the rock. Algal (cryptozoon) structures occur locally throughout the formation, and near the base two algal zones are persistent. Lenses of quartz sandstone and arenaceous dolomites occur locally throughout the Oneota, but except in the lower 20 feet, approximately, the quartz represents only a small percentage of the total rock. Banded chalcedony and drusy quartz line vugs in both the dolomite and chert. Shale is present locally throughout the Oneota but does not seem to occupy particular stratigraphic zones. Iron sulfide, mainly pyrite, is a common constituent of the rock. In the Highland area the unit designated as New Richmond sandstone is an arenaceous shaly bed about 5 feet thick. In the one exposure where this bed is readily identified, a dolomitic sandstone layer about 1 foot thick, is present. The sand is medium to coarse in size and very similar to sand grains of the St. Peter sandstone, which is described below. The Shakopee dolomite is more argillaceous and arenaceous than the Oneota. Algal structures are common. The beds are generally thin and irregular. Shaly and sandy strata are common; locally chert is very abundant, and much of it is oolitic. Middle Ordovician. The Prairie du Chien group is overlain by the St. Peter sandstone. Where observed in the Highland area, this formation is from 48 to 221 feet thick. The sandstone is white to buff, mainly medium grained, but coarse at the top and near the base of the formation. The St. Peter is unmineralized except for local iron sulfide concentrations. Above the St. Peter sandstone, the Platteville formation has the thin Glenwood shale member at its base; the Glenwood is overlain by the Pecatonica dolomite member, which is overlain by the McGregor limestone member, the highest stratigraphic unit penetrated by drilling. A mantle of residual boulders, sand, clay, and soil, which is as much as 8 feet thick, covers the area. Results of geologic mapping Evidences of mineralization. Considerable float galena in many of the stream beds in the Ei sec. 3 Land the NWi sec. 32, T. 7 N., R. IE., and in the SWjNWi sec. 6, T, 6 N., R. 1 E. was found by field investigation of the area before drilling. Much of the galena was not broken up and appeared to be near its source. In a sharp ravine in the northwest corner of sec. 32, T. 7 N., R. IE., galena was found in place, where it is associated with a brown-red clay. The dolomite beds are thin and irregular and are warped upward into a small dome, the top of which has been eroded away exposing the mineral. In the quarry in the NWNWi sec. 32 some galena was recovered as a byproduct in the quarrying activities. The lead mineral here occurs near and in a honeycombed chert layer 2 to 3 feet thick. Galena filling the voids in large free chert blocks may be seen near the entrance to the quarry. Abundant float galena occurs in the stream valley in the SWSEl sec. 31, T. 7 N., R. IE., and a lesser amount is in the stream valley in the SWiNWi sec. 6, T. 6 N., R. IE. Two occurrences of galena seen in outcrops are in a zone 110 to 125 feet below the top of the St. Peter sandstone. A third occurrence also seen in an outcrop is in a zone 140 to 150 feet below the top of the St. Peter.

The pits and caved shafts of mines other than the Ohlerking mine appear to have been no deeper than 30 or 40 feet; in fact, most were very shallow and seem to have been dug to recover only residual galena concentrated at the bedrock surface. Where galena is seen in outcrops,it is associated with thick chert layers and with solutional thinning of beds. No zinc mineral was found in any of the exposures. Structure. The upper surface of the St. Peter sandstone was chosen as the datum plane for structure contours because of the exceedingly irregular upper surface of the Prairie du Chien group. Much of this irregularity is primary and not a reflection of warping and flexing of the strata after deposition of the Prairie du Chien. However, the relief on the upper surface of the St. Peter sandstone is believed to represent adjustment to stresses applied to the strata, and these adjustments account for the fractures that localize mineralization. As seen on the map of the Highland area (pi. 3), the basic structure is a southward-dipping homocline. Superposed on it are northeastward-trending minor corrugations that may be purely superficial because stream dissection has produced moderately steepwalled valleys, and the resulting mass movement of both surficial material and the sandstone bedrock may account for the minor warping. Furthermore, the trend of this minor structure locally tends to parallel the topography. Nevertheless, this structure was prospected because areas of float galena and old lead diggings seem to be located along its trend and because such gentle' structures localize mineral deposits in the upper ore zone in the main part of the mining district. Groups of drill holes alined normal to the trend of the corrugated structure were drilled at three places (pi. 3). Results of exploratory drilling Twelve exploratory holes were drilled between February 22 and May 17, 1951, five on the Steil property, Ni sec. 6, T. 6 N., R. IE., five on the Williams property, SEi sec. 31, T. 7 N. , R. IE., and two on the Wiest property, Si sec. 29, T. 7 N., R. IE. (pi. 3). Samples were taken of cuttings recovered from each 5 feet of drilling and were examined through a binocular microscope. (Summary logs are included on pp. 11-36.) Three holes penetrated zones containing galena, samples of which assayed as high as 1. 2 percent lead, and traces of galena were found in samples from other holes (pi. 4 and summary logs, pp. 11-36). Zinc sulfide in present in the samples only as traces. Iron sulfide is a common constituent of Prairie du Chien rocks, and significant amounts are present in samples from all the exploratory holes except Steil 3 which penetrated the very thick St. Peter sandstone and only 46 feet of dolomite beds of the Prairie du Chien group. Concentrations of iron sulfide occur in two general zones, one being 150 to 160 feet below the top of the St. Peter, the other 195 to 205 feet below that surface. Several samples were estimated to contain more than 10 percent iron sulfide, and an estimate that iron sulfide comprised as much as 25 percent of one of the samples was corroborated by assay. The iron sulfide seems to increase slightly in amount from northwest to southeast in each property as is shown in the cross sections prepared from drill-hole data. This trend is significant because in the upper mineralized zone in the main part of the mining district the larger zinc deposits commonly have an iron sulfide halo that extends peripherally for some distance beyond the zinc ore. At least two periods of chert emplacement are indicated. The earlier chert, which is similar to that common in the Prairie du Chien over a wide area, is glassy and is commonly gray or brown; the later chert is porcelaneous, white or cream, and is seen in the cuttings to have partly or completely Replaced the dolomite. In some of the exploratory holes the later chert seems to be associated with the iron deposits. Considerable drusy quartz and banded chalcedony occur locally in the dolomite and chert. Late dolomite is present in the vugs also. No obvious relation was noted between the late dolomite, the quartz, and the zones mineralized with iron sulfide, although one may exist. The general knowledge of Prairie du Chien stratigraphy has been augmented by data from the drilling. Oolite zones and more poorly defined zones of abundant and sparse chert (pi. 4) were recognized in the study of the samples. Changes in lithology and rock textures were observed, and it was established that the New Richmond sandstone cannot be distinguished with certainty in the Highland area. The drilling indicated that, as in the southern and central parts of the district, the lithology of the Prairie du Chien rocks varies laterally in short distances. Recommendations Continued district-wide study of Prairie du Chien stratigraphy is desirable. At present not enough data regarding these strata in and near the mining district are available to locate and describe persistent zones and stratigraphic markers. Stratigraphic factors affected emplacement of lead and zinc in the Galena- Decorah-Platteville ore zone, and probably the same is true of mineral zones in the Prairie du Chien. Thus a detailed knowledge of the stratigraphy of the mineral-bearing rocks is an important and necessary consideration for prospecting in this group. Although some galena-bearing rock was penetrated in the area drilled, no conclusions about the presence or absence of zinc and lead ore in the, Prairie du Chien strata, generally, can be drawn from the limited drilling described in this report. Future investigation of mineral deposition.in the Prairie du Chien in the Highland area should include: 1. Additional drill holes southeastward along the lines of the exploratory holes drilled in 1950-51. Such drilling may provide data on the increasing concentration of iron sulfide in that direction and on the structural possibilities in these localities.

2. The cleaning out of the shaft and inspection of the old Ohlerking mine workings. The shaft reaches a depth at which it should penetrate the zones of iron deposition recorded in the drill holes on the Williams property. Examination of stopes and drifts in this mine should reveal structural and stratigraphic controls, and the manner of mineral emplacement. Such information can be obtained only partly by drilling. LITERATURE CITED Agnew, A. F., and Heyl, A. V., Jr., 1947, Recent developments in the Wisconsin-Illinois-Iowa leadzinc district: Iowa Acad. Sci. Proc. 1946, vol. 53. p. 228. Behre, C. H., Jr., 1939, Wisconsin-Illinois district, in Bastin, E. S., and others,, Contributions to a knowledge of the lead and zinc deposits of the Mississippi Valley region: Geol. Soc. America Special Paper 24, pp. 67-70. Chamberlin, T. C., 1882, The ore deposits of southwestern Wisconsin: Wisconsin Geol. Survey, Geology of Wisconsin, vol. 4, pp. 516-517. Heyl, A. V., Jr., Lyons, E. J., and Agnew, A. F., 1951, U. S. Geological Survey exploratory drilling in the Prairie du Chien group: U. S. Geol. Survey Circ. 131. Owen, D. D., 1840, Report of a geological exploration of part of Iowa, Wisconsin, and Illinois, 1839: Cong. Doc. 26th Cong. 1st sess., H. Ex. Doc. 239, 161 pp. Thwaites, F. T., and Howell, J. V., 1935, Topography of pre-Cambrian surface: Kansas Geol. Soc. 9th Ann. Field Conf., fig. 227. Thwaites, F. T., Howell, J. V., and Jones, D. D., 1935, Structure of St. Peter sandstone: Kansas Geol. Soc. 9th Ann. Field Conf., fig. 230 Whitney, J. D., 1858, _in Hall, James, and Whitney, J. D., Report on the geological survey of the State of Iowa, vol. 1, pt. 1, Geology, pp. 438-440, [Albany, N. Y.] Willman, H. B., and Reynolds, R. R., 1947, Geological structure of the zinc-lead district: Illinois State Geol. Survey Rept. Inc. 124, pp. 14-15.

GENERALIZED LOGS OF DRILL-HOLE EXPLORATIONS Tete des Morts area, Jackson and Dubuque Counties, Iowa Schenk 1 Location: 3,470ft north, 1,510ft east of southwest corner, sec. 3, T. 87 N., R. 4 E., Iowa. Driller: John Hauser, Sept. 21 to Oct. 5, 1950. Collar elevation: 702. 4 ft. Total depth: 362 ft. Depth to water: 45,137| ft:- 1 Sample study and logging: A. F. Agnew, Oct. 5, Surficial: Soil, loess, dark-brown, silty Depth (feet) Galena dolomite: Noncherty unit: Dolomite, light yellowishbuff, medium-granular, in part crystalline, cinnamon-specked Dolomite, orange-brown, coarsely crystalline Dolomite, light-brown Dolomite, as above, in part medium-granular... Dolomite, medium - granular, in part crystalline, dense Dolomite, as above, red-specked Cherty unit: Dolomite, as above; chert, estimated as 30 percent or lesa Dolomite, drab to brown, coarsely crystalline; drab chert, estimated as 10 percent or less Dolomite, buff-drab, coarsely crystalline; gray to white chert) estimated as 25 percent or less Dolomite, light-brown to grayish-brown; brown chert, estimated as 20 percent or less Dolomite, brown, coarsely crystalline; white chert, estimated as 25 percent or less Dolomite, as above; chert, estimated as 5 percent or less Dolomite, as above; chert, estimated as 40 percent or less 702 - 92i 92-100 132|-155 155 -167| 167|-175 190 -197| 197i-217| 217|-236 1 Driller's log shows 0-22 feet surficial. Depth (feet) Decorah formation: Ion dolomite member ("gray" and "blue" beds): Dolomite, light-gray, coarsely crystalline, silty, black-specked Dolomite, brown, coarsely crystalline, blackspecked; darkgray, mediumcrystalline, and coarsely crystalline, mottled darkgray dolomite . Ion and Guttenberg members: Limestone, gray, dolomitic, very black specked and mottled; sandy with fine to medium quartz and fine phosphate nodules; brownish-gray coarsely crystalline slightly dolomitic sandy limestone; light-brown coarsely crystalline mottled and specked limestone; fossil - iferous Guttenberg limestone member ("oil rock"): Dolomite, brown, fine- to medium-crystalline, mottledbrown; fossiliferous 260 -262| Limestone, brown to lightbrown, finely crystalline, dense, red-specked; fossiliferous . 262-275 Spechts Ferry shale member ("clay bed"): Shale, green, hard, blackspecked 275 -282| Platteville formation: Quimbys Mill member ("glass rock"): Limestone, brown to dark-brown, fine-grained and crystalline, dense, black-specked; dark-brown hard black-specked shale . 282-290 McGregor limestone member ("Trenton"): Limestone, dolomite, grayishbrown, silty, slightly mottled brown; fossiliferous; trace of gray hard shale 290 -29?i Limestone, light-brown, fine-grained, dense; fossiliferous; grayisholive hard brown-streaked shale 297i-302| Limestone, grayish, finegrained, dense, silty

Depth (feet) Platteville formation Continued McGregor limestone member Con.. Limestone, as above; grayish argillaceous material abundant . 307i-312| Limestone, grayishdrab, fine-grained, very silty, with grayish argillaceous material 312-321 Pecatonica dolomite member: Dolomite, brown, finely granular, sugary, brown resinous blebs; trace of brownish-gray organic shale ' 321 -325 Dolomite, mottled-gray, medium-granular, black-specked . 325 -330 Dolomite, caramel, mediumgranular, crystalline 330 -335 Dolomite, brown, finely granular, sugary, very silty; black phosphate nodules; trace of coarse subrounded quartz sand... . 335 -342 Pecatonica and Glenwood members: Dolomite, as above, also sandy with coarse subrounded quartz; phosphate nodules; grayishgreen sandy shale, with organic specks; coarse subrounded quartz sandstone; argillaceous and pyritic cemented 342-346 St. Peter sandstone: Sandstone, quartz, medium to coarse, subrounded; dolomitic and siliceous cement 346 -350 Sandstone, quartz, fine to medium, angular to subangular 350 -352| Sandstone, quartz, coarse to very coarse . 352-358 Sandstone, quartz, fine to medium . 358 -362 Schenk 2 Location: SENWi sec. 3, T. 87 N., R. 4 E., Iowa; 123 feet N. 15° E. from Schenk 1. Drillers: John Hauser, Michael Griffin, Oct. 6 to Oct. 17, 1950. Collar elevation: 730. 0 ft. Total depth: 350 ft. Depth to water: 140 ft. Sample study and logging: A. F. Agnew, Nov. 1950. Depth (feet) Surficial: Loess . Loess; trace of buff granular dolomite 40 - 50l 1 Drillers' log shows 0-40 feet surficial. Depth (feet) Galena dolomite: Noncherty unit: Dolomite, light-gray, medium-granular; yellowish coarsely granular cinnamon specked dolomite . Dolomite, buff to brown, fine- to medium-grained, crystalline to granular Cherty unit: Dolomite, as above; white to brown chert, estimated as 40 percent or less Dolomite, drab, coarsely crystalline; chert, estimated as 25 percent or less... . Dolomite, as above, mottled-gray; chert, estimated as less than 10 percent . Dolomite, brown, coarsely crystalline . Dolomite, as above; buff, chert, estimated as 25 percent . Decorah formation: Ion dolomite member ("gray" beds): Dolomite, grayish-brown, 'coarsely crystalline, black-specked, silty; trace of grayish shale ("felue" beds): Limestone,, gray, coarsely crystalline, silty, very mottled, fossiliferous Ion and Guttenberg-members: Limestone, light-brown, fine-grained, fossiliferous, sandy with medium subrounded quartz Guttenberg limestone member ("oil rock"): Limestone, brown to lightbrown, finely granular to dense, yellow-specked, very fossiliferous . Limestone, as above; limestone, dark-brown, granular, argillaceous Spechts Ferry shale member ("clay bed"): Shale, bluish-green, flaky,*" black-specked; gray-brown hard shale. Drab very finegrained dense very fossiliferous limestone, with phosphate nodules. White limestone . Platteville formation: Quimbys Mill member ("glass rock11 ): Limestone, brown to darkbrown, medium-granular, sugary, fossiliferous; trace of dark-brown hard shale 309-31513

Depth (feet) Platteville formation--Continued McGregor limestone member ("Trenton"): Limestone, gray to grayishbrown, fine-grained, silty; trace of grayish-brown brownspecked shale . [No sample] . [325-330] Limestone, gray to olive, very fine grained, very dense; very fossil - iferous; silty, with greenish argillaceous areas Pecatonica dolomite member: Limestone, dolomitic, grayishbrown, finely granular, silty, yellow-specked . Estimated iron content Galena dolomite--Continued Noncherty unit--Continued Dolomite, yellowishbuff, medium-granular to coarsely-granular, crystalline [No sample] Cherty unit: Dolomite, brown to drab, medium - crystalline; brown-mauve -cream chert Depth (feet) [155-160] Depth (feet) Percent 160-165 2 165-170 4 17.0-175 3 175-180 3 180-185 4 185-190 Decorah formation: Ion dolomite member ("gray"and"blue" beds): Dolomite, drab, coarsely crystalline, gray-specked; trace of dark-greenishgray, silty shale . Guttenberg limestone member ("oil rock"): Limestone, brown to light-brown, finely granular, brownspecked . Spechts Ferry shale member ("clay bed"): Shale, green, fossiliferous; olive hard blackspecked shale Tr. 295-300 Tr. 300-304 304-305 Schenk 3 Location: SEirNWi sec. 3, T. 87 N., R. 4 E., Iowa; 113 ft S. 20° 45 ft W. from Schenk 1. Driller: John Hauser, Oct. 18 to Oct. 27, 1950. Collar elevation: 719. 7 ft. Total depth: 351 ft. Depth to water: 95,145 ft. Sample study and logging: A. F. Agnew, Dec. 1950. Depth (feet) Platteville formation: Quimbys Mill member ("glass rock"): Limestone, buff to brown, finely granular, crystalline, dense; fossiliferous; trace of dark-brown brownspecked shale McGregor limestone member ("Trenton"): Dolomite, grayish-brown to brown, coarsely granular, mostly crystalline Limestone, brownishgray, fine-grained, dense; fossilif erous; argillaceous. Grayish medium-granular silty % dolomite . Dolomite, drab, slightly mottled gray, finely granular, silty Pecatonica dolomite member: Dolomite, as above, but with brown specks; not silty . Estimated iron content Surficial: Loess Galena dolomite: Noncherty unit: Dolomite, gray, mediumgranular; yellowish-brown coarsely granular very cinnamon-specked dolomite , 1 Driller's log shows 0-37 feet surficial. Depth (feet) 180 -182i Percent

Schenk 3--Continued Estimated iron content Continued Depth (feet) Depth (feet) 305 -307i Percent Tr. Tr. Tr. Schenk 4 Location: sec. 3, T. 87 N., R. 4 E., Iowa; 216 ft S. 22° W. from Schenk 1. Drillers: John Hauser, R. E. Griffin, Oct. 28 to Nov. 11, 1950. Collar elevation: 726. 0 ft. Total depth: 335 ft. Depth to water: 97 ft. Sample study and logging: A. F. Agnew, Dec. 20, Surficial: Loess, brown Loess; glacial sand, quartz, chert, quartzite, jasper, coarse to very coarse, subangular . Galena dolomite: Noncherty'unit: Dolomite, light-gray, granular, crystalline; light-brown medium - granular red-specked sandy dolomite; trace of depauperate material . Dolomite, buff to brownish, otherwise as above . Cherty unit: Dolomite, as above; gray to light-brown chert Dolomite, grayish or drab, otherwise as above Dolomite, brown to light-brown, mottled 1 Driller's log shows 0-50 feet surficial. Depth (feet) Decorah formation: Ion dolomite member ("gray" beds): Dolomite, gray to buff, medium-crystalline, black-specked ("blue" beds): Dolomite, light-gray, medium-granular, crystalline, very black specked; in part sandy with medium sub rounded quartz and medium black phosphate nodules Guttenberg limestone member ("oil rock"): Limestone, brown to cream, mediumcrystalline, brownspecked; cream to tan very fine dense red-specked limestone . Spechts Ferry shale member ("clay bed"): Shale, green to grayish, soft; orange-buff fine-grained medium-granular, crystalline fossiliferous limestone; trace of phosphate nodules Platteville formation: Quimbys Mill member ("glass rock"): Limestone, dark-brown to brown, fine-grained, dense, dark-brown specked; trace of dark-brown shale McGregor limestone member ("Trenton"): Limestone, buffish-gray, mottled, finely granular, silty Estimated iron content Depth (feet) Percent Tr. Tr. Tr.

Schenk 4--Continued Estimated iron content--Continued Depth (feet) Depth (feet) Percent Tr. Decorah formation--Continued Spechts Ferry shale member ("clay bed"): Shale, green; limestone, brown, phosphate nodules; trace of light-gray bentonite Schenk 5 Location: sec. 3, T. 87 N. , R. 4 E. , Iowa; 318 ft S. 21° W. from Schenk 1. Drillers: John Hauser, R. E. Griffin, Nov. 14 to Nov. 29, 1950. Collar elevation: 731. 8 ft. Total depth: 340 ft. Depth to water: 145 ft. Sample study and logging: A. F. Agnew, Jan. 1951. Platteville formation: Quimbys Mill member ("glass rock"): Limestone, light- to dark-brown, finely granular, crystalline, dark-brown specked Estimated iron content [ No visible zinc except for a trace at the 65- to 70-foot -depth.] Surficial: Loess, brown . Loess, as above; glacial sand, estimated as much as 70 percent; gray till Till, as above; trace of sand, as above; depauperate pebbles, estimated as 25 percent or less . Galena dolomite: Noncherty unit: Dolomite, brown to lightbrown, finely granular to medium-granular, cinnamonspecked. Cherty unit: Dolomite, light-brown to grayish-brown, mediumcrystalline; white to brown chert . Decorah formation: Ion dolomite member ("gray" and "blue" beds): Dolomite, brown-gray, medium-crystalline, gray-specked; trace of greenish shale . Ion and Guttenberg members: Limestone, dolomitic, grayish-brown, mediumcrystalline, gray-specked; sandy with medium subrounded quarts '.. . Guttenberg limestone member ("oil rock"): Limestone, light-brown to tan, fine-grained, dense; fossiliferous; dark-brown argillaceous matter Depth (feet) Depth (feet) Percent Tr. Tr. Tr. Tr. Tr. Tr. Tr. Schenk 6 Location: SEiNWi sec. 3, T. 87 N., R. 4 E., Iowa; 252 ft N. 24* E. from Schenk 1. Driller: John Hauser, Nov. 30 to Dec. 14, 1950. Collar elevation: 733. 7 ft. Total depth: 315 ft. Depth to water: 150 ft. Sample study and logging: A. F. Agnew, Dec. 1950. Depth (feet) 1 Drillers' log shows 0-57 feet surficial. Surficial: Loess, brown) trace of depauperate pebbles at base..,

Depth (feet) Schenk 6 Continued Estimated iron content Continued Galena dolomite: Noncherty unit: Dolomite, yellowishbrown to brown, mediumgranular, mostly crystalline Cherty unit: Dolomite, grayish-drab to buff, medium - crystalline to coarsely crystalline; brown to flesh-colored chert varying to cotton rock Depth (feet) Decorah formation: Ion dolomite member ("gray" beds): Dolomite, gray to buff, medium-granular, grayspecked. 264-277 ("blue" beds): Limestone, dark-gray to brown, mottled; argillaceous; very fossiliferous; subrounded quartz sand and phosphate nodules Guttenberg limestone-member ("oil rock"): Limestone, light-brown, medium-crystalline, mottled; fossiliferous; silty. Light-brown to tan fine-grained dense argillaceous limestone; with brown specks Spechts Ferry shale member ("clay bed"): Shale, green to gray-green, very fossiliferous. White to light grayish-brown fine-grained limestone containing phosphate nodules and fossils 210-215.. 225-230 . 230-235 . 265-270 . 275-280 , , Schenk 7 Percent Tr. Tr. Tr. Tr. Tr. Tr. Location: NEiSWi sec. 3, T. 87 N., R. 4 E., Iowa; 1, 086 ft S. 32° 30 ft E. from Schenk 1. Drillers: John Hauser, Gilbert Reiter, Dec. 21, 1950, to Jan. 5, 1951. Collar elevation: 720.0 ft. Total depth: 312ft.' Depth to water: Sample study and logging: A. F. Agnew, Jan. 16, 1951. Depth (feet) Surficial: Loess, brown Platteville formation: Quimbys Mill member: Limestone, gray-brown, fine-grained, dense; argillaceous; trace of dark-brown shale Galena dolomite: Noncherty unit: Dolomite, yellowish-buff, medium-granular, crystalline, cinnamon-specked... Cherty unit: Dolomite, brownish-drab, medium-crystalline; gray to brown chert Estimated iron content [No visible zinc except for a trace at the 285- to 290-foot depth] Depth (feet) 165-170 ... 170-175 ... 175-180 ... 180-185 .. 185-190 Percent Decorah formation: Ion dolomite member ("gray" beds): Dolomite, light-gray to brown, medium-crystalline, grayspecked; trace of green hard silty shale ; . ("blue" beds): Dolomite, calcareous, gray, medium-crystalline, gray-specked; in part sandy; greenish argillaceous areas . 1 Drillers' log shows 0-27 feet surficial.

Depth (feet) Decorah formation Continued Guttenberglimestone member ("oilrock"): Limestone, cream to brown, fossiliferous, brown-specked . Spechts Ferry shale member ("clay bed"): Shale, green; bentonite; gray limestone Platteville formation: Quimbys Mill member ("glass rock"):, Limestone, brown to cream, fine-grained, fossiliferous; brown argillaceous areas; trace of dark-brown shale McGregor limestone member ("Trenton"): Limestone, light-gray, fine-grained, silty Depth Estimated iron and manganese content Depth (feet) Percent Iron Manganese 145-150 Tr. 150-155 0.5 155-160 2 Tr. 160-165 6 165-170' 170-175 6 175-180 5 180-185 4 Tr. 185-190 3 Tr. 190-195 Tr. Schenk 8 Location: SEiNWi sec. 3, T. 87 N., R. 4 E., Iowa; 1, 240 ft S. 47° 45 ft E. from Schenk 1. Drillers: John Hauser, Robert Dagenhardt, Jan. 10 to Jan. 18, 1951. Collar elevation: 718. 4 ft. Total depth: 301 ft. Depth to water: 125 ft. Sample study and logging: A. F. Agnew, Feb. 27, 1951. Depth (feet) Decorah formation: Ion dolomite member ("gray" beds): Dolomite, gray, mediumgranular, and buff, mediumcrystalline, gray-specked; some greenish argillaceous matter 250-260 ("blue" beds): Limestone, gray, medium-crystalline, very fossiliferous; in part sandy; greenish argillaceous and shaly material 260-270 Guttenberg' limestone member ("oil rock"): Limestone, cream to buff, fine-grained, dense, fossiliferous; brown shale . 270-285 Spechts Ferry shale member ("clay bed"): Shale, green, flaky, soft; very fossiliferous. Lightgreenish fine-grained limestone containing phosphate nodules . 285-290 Platteville formation: Quimbys Mill member ("glass rock"): Limestone, tan to dark-brown, fine-grained, dense; brownish argillaceous areas. Darkbrown shale . 290-300 McGregor limestone member ("Trenton"): Limestone, gray, finely granular, sugary . 300-301 Schenk 9 Location: SWiNEi sec. 3, T. 87 N., R. 4 E., Iowa; 1, 634 ft S. 62° E. from Schenk 1. Driller: Robert Dagenhardt, Jan. 20 to Jan. 31, 1951. Collar elevation: 720.4 ft. Total depth: 305 ft. Depth to water: 125 ft. Sample study and logging: A. F. Agnew, Feb. 27, Depth (feet) Surficial: Loess, brown. Surficial: Loess, brown Galena dolomite: Noncherty unit: Dolomite, yellowish-brown, medium-granular, crystalline Cherty unit: Dolomite, grayishbrown; chert Galena dolomite: Noncherty unit: Dolomite, lightbrown, mediumgranulaE Cherty unit: Dolomite, grayishbrown; grayishbrown chert 0- 38* 1 Drillers' tog shows feet surficial. 1 Driller's log shows 0-35 feet surficial.

Depth (feet) Decorah formation: Ion dolomite member ("gray" beds): Dolomite, light-gray to grayish-brown, mediumcrystalline, gray-specked; in part silty . ("blue" beds): Limestone, gray, medium-granular, crystalline, grayspecked; fossiliferous; in part sandy Guttenberg limestone member (oil rock"): Limestone, brown to buff, fine-grained, dense, mottled; fossiliferous; brown shale . Spechts Ferry shale member: Shale, green, very fossiliferous; cream finegrained dense fossiliferous limestone, containing phosphate nodules . Platteville formation: Quimbys Mill member ("glass rock"): Limestone, brown to darkbrown, fine-grained, dense; trace of dark-brown shale McGregor limestone member ("Trenton"): Limestone, light-brownish gray, finely granular, sugary, slightly mottled Kohlenberg 1 Location: 4, 302 ft north, 504 ft west of southeast corner, sec. 4, T. 87 N., R. 4 E., Iowa. Drillers: John Hauser, Gilbert Reiter, Dec. 6 to Dec. 26, 1950. Collar elevation: 732.0 ft. Total depth: 244ft. Depth to water: 215 ft. Sample study and logging: A. F-. Agnew, Jan. 16, Surficial: Loess, brown; glacial sand . Depth (feet) Galena dolomite: Noncherty unit: Dolomite, yellowishbrown, medium-granular; in part silty Dolomite, as above; caramel dull gravel caved).. 1 Drillers' log shows 0-15 feet surficial. Depth (feet) Galena dolomite Continued Noncherty unit Continued Dolomite, brown, mottled, granular, brown-specked . Cherty unit: Dolomite, as above; caramel to brown to pink chert; buff to cream fine- and medium-grained limestone; much calcite Dolomite, as above; grayisnbrown medium -crystalline vuggy dolomite; calcite, limonite; chert, as above 155-205 Dolomite, brown as above; dolomite, calcareous, buff, calcite. 205-210 [No sample] [210-230] Dolomite, brown and buff, as above . Decorah formation: Ion dolomite member ("gray" beds): Limestone, lightbrownish, mediumgranular; in part grayspecked; much calcite; trace of olive-green black-specked silty shale [No sample] [231-240] [240-244] Drillers reported considerable difficulty in the lower part of the hole. At 214 feet a "pitchoff" (fracture that turned the bit away from vertical) was penetrated. The rock was hard drilling until 219 feet, where a second pitchoff was struck. From 219 to 225 feet, soft drilling was accompanied by sanding of the hole. At 225 feet the hole was reamed and casing was set to stop the sanding. From 225 to 230 feet drilling required 2 days (normal footage per,day is 30 to 40 feet). The hole was reamed to 230 feet and casing set at that depth. From 215 to 230 feet no cuttings were recovered because flow of water underground washed them away in a fracture. Drilling proceeded in soft rock to 244 feet, where two bits and the bailer were stuck. After these were recovered, rocks and a fence post .thrown into the hole were carried away by the underground flow of water, as were the cuttings for the 240- to 244-foot interval. The hole was abandoned. The cuttings from 230 to 240 feet indicate that the trouble was caused by an "opening" in a crevice zone and not by a slump joint. Estimated iron content Depth (feet) Percent Tr.

Kohlenberg I Continued Estimated iron content Continued Depth (feet) Depth (feet) Kohlenberg 2 Percent '5 Platteville formation: Quimbys Mill member ("glass rock"): Limestone, cream, finegrained; dolomitic brown fine-grained argillaceous limestone, containing fossils; trace of darkbrown shale McGregor limestone member ("Trenton"): Trace of limestone, light-gray, finely granular, sugary Location: NENE-? sec. 4, T. 87 N., R. 4 E., Iowa; 442 ft N. 44° E. from Kohlenberg 1. Driller: John Hauser, Dec. 28, 1950,to Jan. 9, Collar elevation: 689. 0 ft. Total depth: 245 ft. Depth to water: 110 ft. Sample study and logging: A. F. Agnew, Jan. 16, Galena dolomite: Noncherty unit: Dolomite, yellowishbuff, medium-granular, silty Cherty unit: Dolomite, as above, mottled; chert Dolomite, calcareous, light-brown, mediumgranular, crystalline; white medium-crystal-

line limestone; chert Depth (feet) Kohlenberg 3 Location: SEiSEi sec. 33, T. 88 N. , R. 4 E. , Iowa; 965 ft N. 23° E. from Kohlenberg 1. Driller: John Hauser, Jan. 15 to Jan. 23, 1951. Collar elevation: 734. 7 ft. Total depth: 291 ft. Depth to water: 160ft. Sample study and logging: A. F. Agnew, Feb. 28,1951. Depth (feet) Surficial: Loess, brown, Galena dolomite: Noncherty unit: Dolomite, yellowish-brown, medium-granular Cherty unit: Dolomite, as above; chert Dolomite, as above; in part calcareous Decorah formation: Ion dolomite member ("gray" beds): Dolomite, gray to buff, mediumcrystalline, mottled; greenish and brownisholive black-specked shale . ("blue" beds): Limestone, dolomitic, gray, mediumcrystalline, argillaceous; mottled, silty; fossiliferous Guttenberg limestone member ("oil rock"): Limestone, cream to brown, fine-grained, very fossiliferous Spechts Ferry shale member ("clay bed"): Shale, green, splintery; phosphate nodules; bentonite 1 Driller's log shows 0-2% feet surficial. Decorah formation: Ion dolomite member ("gray" and "blue" beds): Limestone, brown to cream to gray, in part mottled olive; trace of olive shale Limestone, as above, silty, black-specked, fossiliferous; fine phosphate nodules Guttenberg limestone member ("oil rock"): Limestone, cream to brown, fine-grained, dense, brownspecked; brown shale Spechts Ferry shale member ("clay bed"): Shale, green, soft; grayish-brown fine-grained fossiliferous limestone, containing phosphate nodules 275-281 Platteville formation: Quimbys Mill member ("glass rock"): Limestone, light-brown to gray, fine-grained, dense, fossil-, iferous

Kohlenberg 4 Estimated manganese content Location: NEiNEi sec. 4, T. 87 N., R. 4 E., Iowa; 42ft N. 44°31 ft W. from Kohlenberg 1. Driller: John Hauser, Jan. 25 to Feb. 15, 1951. Collar elevation: 734. 5 ft. Total depth: 287 ft. Depth to water: Sample study and logging: A. F. Agnew, Feb. 28, Depth (feet) Percent 235-240 Highland area, Iowa and Grant Counties, Wis. Surficial: Loess, glacial sand Depth (feet) Galena dolomite: Noncherty unit: Dolomite, buff, mediumgranular, cinnamonspecked; trace of Silurian-type chert (caving) Cherty unit: Dolomite, as above; chert Dolomite, as above; white medium - crystalline limestone Decorah formation: Ion dolomite member ("gray" beds): Limestone, light-gray to buff, mediumcrystalline, grayspecked; green and olive silty shale ("blue" beds): Limestone, light-gray, finely crystalline, mottled, fossiliferous, sandy Guttenberg limestone member ("oil rock"): Limestone, cream to tan, finely crystalline, granular, dense, brown-specked, fossiliferous Spechts Ferry shale member ("clay bed"): Shale, green, fossiliferous, phosphate nodules Platteville formation: Quimbys Mill member ("glass rock"): Calcareous rock flour, tan; trace of dark-brown shale McGregor limestone member ("Trenton"): Limestone, gray, finely granular Wiest 1 Location: 1,130 ft north, 1,805 ft east of southwest corner, sec. 29, T. 7 N. , R. IE., Wis. Drillers: J. Hauser, R. Dagenhardt, Mar. 22 to Apr. 14, 1951. Collar elevation: 1, 084. 8 ft. Total depth: 275 ft. Depth to water: 115 ft. Sample study and logging: Arthur E. Flint, Apr. 20, [Percentages estimated] Soil, residual clay, Platteville formation: Glenwood shale member: Shale, gray-green, partly arenaceous Depth (feet) St. Peter sandstone: Sandstone, quartz, lightgray, buff, medium-coarse; coarse upper 10 feet, 65 to 75 feet, and lower 20 feet. Many grains show crystal overgrowths, local dolomitic cement . Prarie du Chien group: Shakopee dolomite: Dolomite, buff, fine- and medium-grained; green arenaceous shale, very common; chert, sparse; quartz sand (caved), common Dolomite, as above; oolitic chert, abundant; green shale, caving(?) common; quartz sand, caved, common; iron 1 percent Dolomite, as above, partly arenaceous; chert, as above; quartz sand, common; iron 1 percent Dolomite, buff, fine-grained; oolitic chert, very common; quartz sand, common; iron -|'percent'

Depth (feet) Prairie du Chien group--Continued New Richmond sandstone(?): Dolomite, brown, very arenaceous; green arenaceous shale; chert, sparse; quartz sand, abundant; iron 1 percent . Oneota dolomite: Dolomite, brown, fine- and medium-grained; chert, abundant; green shale and quartz sand, common; iron -1 percent Dolomite, as above; chert, common; green shale and quartz sand, sparse; iron -7f percent Dolomite, as above; chert, very abundant; green shale, common; iron 1 percent . Dolomite, as above; chert, very abundant; green shale, sparse; iron -1 percent . Dolomite, as above; chert, very abundant; shale, as above; iron -1 percent Dolomite, as above; chert, very abundant; limonite and hematite estimated as 3 percent . Dolomite and chert, as above; green shale, very common; iron percent... Dolomite and chert, as above;trace of glauconite . Dolomite, as above; chert estimated as 90 percent of sample; green shale, sparse . Dolomite, as above; chert, very abundant; iron 1 percent Dolomite, gray, fine- and medium-grained; chert, common; iron -1 percent . Dolomite, as above, medium-grained; chert, common; trace of glauconite Dolomite, as above; chert, common to sparse; iron -1 percent Dolomite, brown, mediumgrained, granular; chert, as above; iron I percent . Dolomite, as above; chert, abundant; iron 4 percent Prairie du Chien group Continued Oneota dolomite Continued Dolomite, as above; chert, sparse; iron 1 percent Dolomite, as above; browngreen shale, common; iron 1 percent . Dolomite, as above; chert and shale, sparse . Dolomite, as above; green shale, sparse . Dolomite, as above; oolitic chert, abundant Dolomite, as above, granular; green shale, common . Dolomite, as above, partly oolitic; green shale, oolitic chert, and quartz sand, sparse . Dolomite, as above, arenaceous; chert, as above; green shale and quartz sand, sparse Dolomite, as above; mediumcoarse rounded quartz sa'ndstone, abundant Dolomite, as above; chert, sparse; sandstone, as above, abundant . Depth (feet) Wiest 2 Location:. Sec. 29. T. 7N., R. 1 E., Wis.; 315 ft S. 52°E. from Wiest 1. Drillers: R. Dagenhardt, J. Dagenhardt, May 3 to May 17, 1951. Collar elevation: 1, 083. 4 ft. Total depth: 235 ft. Depth to water: Sample study and logging: Arthur E. Flint, May 27, 1951. [Percentages estimated] Soil, residual clay, St. Peter sandstone: Sandstone, quartz, lightgray and buff, medium and medium-coarse except coarse near top andbase.., Depth (feet) Prairie du Chien group: Shakopee dolomite: Shale, buff, very abundant; oolitic chert, abundant; brown- gray dolomite, sparse Dolomite, brown, fine- and medium-grained; buff shale, very abundant; quartz sahd, very common (caving)

Depth (feet) Depth (feet) Prairie du Chien group Continued Shakopee dolomite Continued Dolomite, as above, fine- and medium-grained; oolitic chert, abundant; quartz sand, sparse; iron -1 percent Dolomite, chert, and quartz sand, as above . Dolomite, as above; partly oolitic chert; quartz sand as above; iron -1 percent Dolomite and chert, as above; quartz sand, common; green shale, sparse; iron -1 percent Dolomite, as above; chert, as above, abundant; red-brown shale, very common; quartz sand, sparse;iron 1 percent Dolomite, as above, partly arenaceous; chert, common; iron -1 percent Dolomite, as above; chert, very common; green shale and quartz sand, sparse . Dolomite, nonarenaceous, and chert, as above; quartz sand, sparse; iron -1 percent' . Dolomite, brown, finland medium-grained; chert, common; iron +1 percent Dolomite and chert, as above; quartz sand, common; iron -1 percent New Richmond sandstone(?): Dolomite, as above, partly arenaceous; green-brown arenaceous shale, common; chert, common; iron -1 percent . Oneota dolomite: Dolomite, as above; chert, abundant; iron -1 percent . Dolomite, brown, fine- and medium-grained; chert, common Dolomite, as above; chert, as above, sparse to common . Dolomite, as above; chert, as above; iron -1 percent . Dolomite, as above; chert, abundant; redbrown shale, sparse to common; iron 3 percent . Prairie du Chien group Continued Oneota dolomite Continued Dolomite, gray-brown, fine- and medium-grained; chert, abundant; iron 5 percent . Dolomite, as above; chert, very abundant; iron 6 percent . Dolomite, as above; chert, abundant; iron 2 percent; trace of zinc . Dolomite, gray, mediumgrained; chert, very abundant; iron 1.percent; trace of zinc Dolomite and chert, as above; iron 1 percent; trace of zinc Dolomite, as above; chert, sparse to common; iron

+1 percent . Dolomite, as above; chert, sparse;, iron + 1 percent Dolomite and chert, as above; iron -1 percent . Dolomite, as above; iron -1 percent . Dolomite, as above; chert, sparse to common Dolomite, as above; chert, sparse . Dolomite and chert, as above;iron 1 percent Dolomite, as above; gray shale, very common; iron -1 percent . Dolomite, gray, medium- . grained, granular; gray shale, abundant Dolomite, as above; chert, sparse . Dolomite, as above; chert, sparse to common; iron percent . Dolomite, as above; chert, sparse . Williams 1 Location: 1,455 ft north, 1, 700 ft west of southeast corner, sec. 31, T. 7 N., R. IE., Wis. Driller: R. Dagenhardt, Feb. 22 to Mar. 5, 1951. Collar elevation: 1,116. 6 ft. Total depth: 330ft. Depth to water: 50 ft. Sample study and logging: Arthur'E. Flint, Mar. 10, [Percentages estimated] Soil, residual clay, weathered limestone fragments Depth (feet)

Depth (feet) Depth (feet) Platteville formation: McGregor limestone member: Limestone, brown and gray, medium- and fine-grained, fossiliferous Pecatonica dolomite member: Dolomite, gray and buff, medium-granular, arenaceous in lower 2 feet; phosphatic nodules common near base Glenwood shale member: Shale, gray-green; a few phosphatic nodules; limonite common St Peter sandstone: Sandstone, quartz, light-gray and buff, medium-grained except coarse near base in the 85- to 90-foot sample and near top of formation; limonite common near base . Prairie du Chien group: Shakopee dolomite: Shale, light-green and gray; oolitic and arenaceous chert, common; limonite, common . Dolomite and dolomitic siltstone, buff, finegrained; oolitic chert, very abundant; green shale, common; quartz sand (caving) and limonite, common; trace of glauconite . Dolomite, light-brown, some arenaceous, fine- and mediumgrained; chert, much is. oolitic, abundant; gray and green shale, very common . Dolomite, as above; chert, some oolitic, very common . Dolomite, as above; chert, very common; quartz sand cemented with silica, very common Dolomite, as above, much is arenaceous, and dolomitic sandstone; chert, sparse; quartz sand, common New Richmond sandstone(?): Dolomite, as above; chert, sparse; green shale, common; quartz sand cemented with limonite, common . Prairie du Chien group--Continued Oneota dolomite: Dolomite, as above, some medium-grained; chert, sparse to common; quartz sand, common . Chert, light-gray, glassy, estimated as 80 percent of sample; dolomite, as above Dolomite, as above, medium-grained; chert, as above, abundant Dolomite, as above; chert, some oolitic, very abundant . Dolomite, as above; chert, some oolitic, very abundant; green shale, sparse . Dolomite, as above; chert, some oolitic, very abundant . Dolomite, as above; chert, some oolitic, common . Dolomite, as above; chert, some oolitic, common . Dolomite, gray, medium-grained; chert, some is oolitic, very abundant; iron, trace . Dolomite, as above; chert, some arenaceous, very abundant; green shale, very common; iron +2 percent . Dolomite, as above; chert, very abundant; quartz sand, common; iron +2 percent . Dolomite, as above; chert, very abundant; iron 2 percent . Dolomite, as above; chert abundant; quartz sand, common; iron +2 percent Dolomite, as above; chert, very common; quartz sand, as above; iron -1 percent Dolomite, as above; chert, sparse,to common; quartz sand, as above; iron -j percent . Dolomite, as above; chert, sparse to common; iron -1 percent . Dolomite, as above; chert, sparse;iron -1 percent .

Prairie du Chien group Continued Oneota dolomite--Continued Dolomite, as above; chert, very common; iron 2percent Dolomite, brown, mediumgrained; chert, sparse; iron 1 percent Dolomite, as above; chert, some oolitic, common; green shale, common; iron 1 percent . Dolomite, gray, mediumgrained; green shale, very common; chert, sparse; iron 1 percent . Dolomite, as above; chert, sparse; iron -1 percent . Dolomite, brown, mediumgrained; chert, some oolitic, sparse to common; quartz sand, common . Dolomite, as above; chert, sparse; gray arenaceous shale, sparse to common; quartz sand, common . Dolomite, as above; chert, sparse; quartz sand, very common . Dolomite, as above; chert, oolitic, very common; quartz sand, sparse Dolomite, as above; chert, partly oolitic, abundant . Dolomite, as above; chert, nonoolitic, very common . Dolomite, as above; chert, a little is oolitic, common; quartz sand, common . Dolomite, as above, arenaceous; quartz sand, common Dolomite, buff, arenaceous, oolitic,, and dolomitic sandstone; chert, sparse to common . Dolomite and dolomitic sandstone, as above;. chert, sparse; quartz sand estimated as 30 percent of sample; trace of green shale . Sandstone, dolomitic, buff, mediumcoarse, rounded, and arenaceous dolomite; quartz sand, abundant; trace of glauconite . Depth (feet) Depth (feet) Trempealeau formation (Cambrian): Jordan sandstone member: Sandstone, quartz, clear, medium-grained, poorly sorted, some dolomitic cement Williams 2 Location: Sec. 31, T. 7 N., R. 1 E., Wis.; 335 ft N. '318 10 ft W. from Williams 1. Driller: R. Dagenhardt, Mar. 7 to Mar. 16, 1951. Collar elevation: 1,097. 1 ft. Total depth: 295 ft. Depth to water: 105 ft. Sample study and logging: Arthur E. Flint, Mar. 20, [Percentages estimated] Soil, residual clay, weathered limestone. Platteville formation: McGregor limestone member: Limestone, gray-brown, fine- and medium-grained, fossiliferous . Pecatonica dolomite member: Dolomite, gray and buff, medium-grained, arenaceous in lower 3 feet; phosphatic nodules and limonite common near base . Glenwood shale member: Shale, gray-green, arenaceous in part; phosphatic nodules and marcasite partly oxidized, common, St. Peter sandstone: Sandstone, quartz, lightgray and buff, mediumgrained except coarse at top and through lower 20 feet, rounded, some grains frosted, pitted . Depth (feet) Prairie du Chien group: Shakopee dolomite: Shale, gray; brown-gray dolomite, sparse Dolomite, brown-gray, fine- and medium-grained, some is arenaceous; oolitic chert, very abundant; some caving sandstone . Dolomite and chert, as above; gray-green shale, common; trace of glauconite

Prairie du Chien group Continued Shakopee dolomite Continued Dolomite, as above, much is arenaceous; chert, some is oolitic, abundant; shale, as above, common to very common Dolomite, gray, as above, little is arenaceous; chert, as above, common; trace of glauconite; shale, as above,, common . Dolomite, as above; chert, sparse to common; shale, as above, very common; trace of glauconite . Dolomite, as above; chert, sparse; shale, as above, common . New Richmond sandstone(?): Dolomite, gray and brown, fine- and medium-grained, much is arenaceous; chert, sparse; green shale, common; a little quartz sand . Oneota dolomite; Dolomite, as above; chert and gray shale, sparse . Dolomite, as above, partly arenaceous; chert, abundant . Dolomite, brown and buff, fine- and medium-grained; chert, abundant; gray-green shale, sparse; lead i percent . Dolomite, as above; chert, common; green shale, sparse; trace of lead . Dolomite, as above, partly arenaceous; graygreen shale, sparse to common; chert, sparse Dolomite, as above, nonarenaceous; chert, abundant; trace of green shale; iron 1 percent Dolomite, as above; chert, abundant; iron 1 percent Dolomite, as above; chert, very common Dolomite, gray, fine- and medium-grained; chert, very common; green shale, sparse to common; iron +3 percent... Dolomite, as above; chert, abundant; iron+3 percent Depth Depth (feet) (feet) Prairie du Chien group Continued Oneota dolomite Continued Dolomite, as above; chert, abundant; iron +2 percent Dolomite, as above: chert, sparse to common; iron +2percent . Dolomite, as above; chert, common to sparse; iron -1 percent; trace of lead Dolomite, as above; chert, sparse; iron i percent . Dolomite, as above; chert, common to sparse Dolomite, as above; chert, sparse; iron 1 percent Dolomite, as above; chert, sparse; iron -1 percent; trace of lead Dolomite, brown, mediumgrained; chert, sparse to common; iron -1 percent . Dolomite and chert, as above; gray-green shale, very common; quartz sand, common; trace of glauconite; iron -1 percent . Dolomite, as above; chert and shale;sparse . Dolomite, gray, fine- and medium-grained . Dolomite, as above; trace of arenaceous green shale; dolomitic sandstone, common to sparse . Dolomite, brown, mediumgrained; green arenaceous shale, common; quartz sand, sparse . Dolomite, as above; trace of chert and green shale; quartz sand, sparse . Dolomite, as above; chert, partly oolitic, very common . Dolomite, as above . Dolomite, as above, arenaceous Dolomite, as above, arenaceous and oolitic; trace of chert, oolitic

Williams 3 Location: Sec. 31, T. 7 N., R. IE., Wis.; 265 ft S. 43° E. from Williams 1. Driller: R. Dagenhardt, Mar. 17 to Mar. 30, 1951. Collar elevation: 1,093. 3 ft. Total depth: 290 ft. Depth to water: 155 ft. Sample study and logging: Arthur E. Flint, Mar. 3, Depth (feet) [Percentages estimated] Soil, residual clay, weathered limestone, Depth (feet) Platteville formation: McGregor limestone member: Limestone, brown-gray, fine -grained Pecatonica dolomite member: Dolomite, gray and buff, medium-grained, arenaceous near . base Glenwood shale member: Shale, gray-green, a few phosphatic nodules St. Peter sandstone: Sandstone, quartz, lightgray and buff, rounded, medium-grained except coarse in upper 8 feet and lower 10 feet Prairie du Chien group: Shakope'e dolomite: Dolomite,; buff, fine- and mediumgrained; oolitic chert, common; green glauconitic shale, common Dolomite, as above; chert, sparse Dolomite, buff, medium-grained Dolomite, brown, fine- and medium-grained; chert, sparse to common Dolomite, as above, partly oolitic; chert, sparse Dolomite, as above, nonoolitic; oolitic chert, very abundant; green arenaceous shale, common Dolomite, as above; oolitic chert, abundant; gray-green shale and quartz sand, common Prairie du Chien group Continued Shakopee dolomite Continued Dolomite, as above, but fine-grained, dense; oolitic chert, very abundant; shale and quartz sand, as above . Dolomite, as above, finland medium-grained; chert, common to sparse . Dolomite, as above, fine- and medium-grained . New Richmond sandstone(?): Dolomite, brown, mediumgrained; chert, sparse . Oneota dolomite: Dolomite, as above; chert, very abundant . Dolomite, as above; chert, very abundant Dolomite, gray, fine- and medium-grained; chert, abundant Dolomite, brown, fine- and medium-grained; chert, sparse to common Dolomite, gray, fine- and medium-grained; chert, common . Dolomite, as above; chert, abundant . Dolomite,as above; chert, abundant; iron 2 percent Dolomite, as above; chert, common . Dolomite, as above; chert, abundant Dolomite, gray, mediumgrained; chert, abundant Dolomite, as above; chert, abundant . Dolomite, as above; chert, abundant; iron + 1 percent . Dolomite, brown, mediumgrained; chert, abundant; iron -1 percent . Dolomite, gray, mediumgrained; chert, sparse to common; iron - § percent Dolomite, as above; chert, sparse Dolomite, as above; chert, abundant; iron 3 percent . Dolomite, as above; chert, abundant; iron 2 percent . Dolomite, as above; chert, sparse; iron -i percent

Prairie du Chien Continued Oneota dolomite Continued Dolomite, gray, granular; chert, partly oolitic, sparse Dolomite, as above; trace of chert Dolomite, brown, medium-grained, arenaceous; angular quartz sand, very abundant Dolomite, as above, nonarenaceous; quartz sand, as above, very abundant Dolomite, as above; chert, abundant Dolomite, as above, partly oolitic; oolitic chert, abundant; quartz sand, sparse to common Dolomite, as above; partly oolitic chert, abundant; quartz sand, as above Dolomite, as above, partly arenaceous and oolitic;chert and quartz sand, sparse Dolomite, as above, arenaceous and oolitic; oolitic chert, common; quartz sand, sparse; iron I percent Dolomite, as above, arenaceous, glauconitic; chert and quartz sand, sparse Depth (feet) Depth (feet) Williams 4 Location: Sec. 31, T. 7 N., R. 1 E., Wis.; 525 ft S. 45°50 ft E. frpm Williams 1. Driller: R. Dagenhardt, Apr. 6 to Apr. 17, 1951. Collar elevation: 1,080. 2 ft. Total depth: 280 ft. Depth to water: 145 ft. Sample study and logging: Arthur E. Flint, Apr. 20, [Percentages estimated, except where assay values are indicated] Soil, residual clay and chert Platteville formation: Glenwood shale member: Shale, gray-green, oxidized in part to red Depth (feet) St. Peter sandstone: Sandstone, quartz, licrhtgray and buff, rounded, many grains frosted, medium-grained except coarse in upper 10 feet and lower 8 feet, traces of white porcellaneous'chert in lower 30 feet (may be caved) Prairie du Chien group: Shakopee dolomite: Shale, brown-buff; dolomite, buff, sparse . Dolomite, brown, fine- and medium-grained; oolitic chert, sparse; quartz sand (caving) . Dolomite, as above, partly arenaceous; chert, sparse; quartz sand, as above . Dolomite, as above, fine- and medium-grained . Dolomite, as above, partly oolitic; partly oolitic chert, very common; brown shale, sparse Dolomite, as above, nonoolitic; partly oolitic chert, abundant . Dolomite, as above, partly arenaceous; very oolitic chert, abundant; green arenaceous shale, common . Dolomite, as above, some very finegrained; partly oolitic chert, abundant; quartz sand and green shale, sparse to common . Dolomite, as above, partly arenaceous; quartz sand, sparse; trace of glauconite . New Richmond sandstone(?): Dolomite, brown, partly arenaceous, and dolomitic sandstone; green shale, sparse to common . Oneota dolomite: Dolomite, brown, fine- and medium-grained Dolomite, brown and gray, medium - and fine -grained; chert, abundant . Dolomite, as-above; chert, very common .

Prairie du Chien group--Continued Oneota dolomite--Continued Dolomite, as above; chert, sparse; trace of lead Dolomite, gray, medium-grained; chert, sparse . Dolomite, as above, fine- and mediumgrained; glauconitic chert, abundant Dolomite, brown, ve.i*y fine and medi um - grained, partly arenaceous; chert, abundant . Dolomite, as above; chert, very abundant; iron 2 percent; lead if percent Dolomite, as above; chert, very abundant; green shale, sparse; iron 2 percent; trace of lead Dolomite and chert, as above; iron I percent; lead i percent Dolomite, as above; chert, abundant; iron percent; trace of lead . Dolomite and chert, as above; iron if percent Dolomite, as above; chert, very common; iron f percent; trace of lead Dolomite, gray, finland medium-grained; chert, sparse; trace of lead . Dolomite, as above, medium-grained; chert, sparse Dolomite, as above; chert, common to sparse; iron assayed 12. 65 percent of sample; zinc assayed trace . Dolomite and chert, as above; iron 8 percent . Dolomite and chert, as above; iron 6 percent . Dolomite, as above; chert, sparse; iron 2 percent . Dolomite and chert, as above; iron 1 percent . Dolomite and chert, as above; iron 2 percent... Depth (feet) Depth (feet) Prairie du Chien Continued Oneota dolomite Continued Dolomite, brown, medium-grained; chert, sparse;iron 1 percent Dolomite, as above Dolomite, as above; partly oolitic chert, very abundant Dolomite, as above; chert and quartz sand, sparse to common Dolomite, as above; partly oolitic chert, common; quartz sand, sparse Dolomite, as above; partly oolitic chert, common to sparse Dolomite, brown, mediumgrained, arenaceous, partly glauconitic; quartz sand common; trace of iron Dolomite, as above, arenaceous, and oolitic; partly oolitic chert, sparse; quartz sand, sparse Williams 5 Location: Sec. 31, T. 7 N., R. IE., Wis.; 860ft S. 46°45ftE. from Williams 1. Driller: R. Dagenhardt, Apr. 18 to Apr. 28, 1951. Collar elevation: 1, 072. 2 ft. Total depth: 275 ft. Depth to water: 25 ft. Sample study and logging: Arthur E. Flint, Apr. 30, [Percentages estimated] Soil, alluvium, silt and fine quartz sand Depth (feet) St. Peter sandstone: Sandstone, quartz, lightgray and buff, medium - grained exeept coarse in upper 5 feet, 35- to 50-foot sample, and lower 17 feet, rounded, some grains frosted, overgrowths on grains in upper 15 feet common

Depth (feet) Depth (feet) Prairie du Chien group: Shakopee dolomite: Shale, green; oolitic chert, common; arenaceous fine- and mediumgrained dolomite, sparse . Dolomite, buff, finland medium-grained, arenaceous; oolitic chert, abundant; buff arenaceous shale, common; quartz sand (caving), common . Dolomite, brown, as above; oolitic chert, very common; quartz sand, sparse . Dolomite, as above; oolitic chert, sparse to common; green glauconitic shale, common; quartz sand, sparse Dolomite, as above, partly arenaceous; chert and quartz sand, sparse; iron -1 percent New Richmond sandstp,ne(?): Dolomite, as above; green arenaceous shale, very common; quartz sand, sparse; iron +1 percent Oneota dolomite: Dolomite, as above; chert, abundant; green shale, sparse; iron 1 percent Dolomite, gray, nonarenaceous; chert, abundant; green shale, common; trace of lead Dolomite and chert, as above; shale, as above, sparse; trace of lead Dolomite, as above; chert, sparse; quartz sand, sparse . Dolomite, as above, partly arenaceous; chert and shale, sparse Dolomite, as above; chert, common to sparse; trace of lead Dolomite, gray, granular, mediumgrained; green-brown shale, very common; chert, sparse; trace of glauconite; iron percent. Prairie du Chien group--Continued Oneota dolomite--Continued Dolomite, brown, gray, fine- and medium - grained; chert, common . Dolomite, as above; chert, very abundant; green shale, very common Dolomite, as above, partly medium-grained; chert, abundant; green shale, common; iron 2 percent . Dolomite, as above; chert, very abundant; iron + 1 percent . Dolomite, as above, medium-grained; chert, abundant; iron percent . Dolomite and chert, as above . Dolomite, as above; chert, sparse . Dolomite, gray, mediumgrained; chert, sparse; iron4 percent Dolomite, as above; iron 5 percent . Dolomite, as above; iron 2 percent . Dolomite, gray-brown, medium-grained; iron +1 percent . Dolomite, gray, mediumgrained; iron Dolomite, light-buff, medium-grained; white decomposed chert, sparse; iron percent . Dolomite, brown-gray, medium-grained; chert, sparse . Dolomite, as above . Dolomite, as above; oolitic chert, very common; green-brown arenaceous glauconitic shale, common; trace of glauconite . Dolomite, brown, mediumgrained, partly arenaceous; green glauconitic arenaceous shale, common Dolomite, as above, arenaceous and oolitic; shale, as above, common; chert, sparse; iron percent . Dolomite, as above, very arenaceous and glauconitic; iron 2 percent Dolomite, as above, arenaceous and oolitic; oolitic chert, sparse; iron -i percent .

Steil 1 Location: 165 ft south, 1, 685 ft east of northwest corner, sec. 6, T. 6 N., R. 1 E., Wis. Driller: John Hauser, Feb. 22 to Mar. 1, 1951. Collar elevation: 1,119. 8 ft. Total depth: 350ft. Depth to water: 45 ft. Sample study and logging: Arthur E. Flint, Mar. 8, Depth (feet)' [Percentages estimated] Depth (feet) Soil, residual clay and weathered limestone (Quimbys Mill?) in lower 8 feet Platteville formation: McGregor limestone member: Limestone, mediumgray, mediumgrained 20 to 33 feet; otherwise fine- and very fine grained; fossiliferous Pecatonica dolomite member: Dolomite, mediumgray, weathers buff; quartz sand and phosphatic nodules at base Glenwood shale member: Shale, gray-green, arenaceous; limonite, phosphatic nodules, very common St. Peter'sandstone: Sandstone, quartz, lightgray, rounded, mediumfine except coarse in upper 10 feet and lower 15 feet Prairie du Chien group: Shakopee dolomite: Shale, green, arenaceous 151 to 153 feet; graybrown fine- and mediumgrained dolomite; some arenaceous oolitic chert; glauconite, common._, Dolomite, as above, nonarenaceous; quartz sand (mostly caving), 15 percent of sample; trace of green shale . Dolomite, as above, some arenaceous; oolitic chert, abundant . Dolomite, as above; chert, a*s above, partly oolitic, abundant; sparse green shale and quartz sand (caving) Prairie du Chien group--Continued Shakopee dolomite Continued Dolomite, as above; chert, as above, some oolitic, common; quartz sand, sparse . New Richmond sandstone(?): Dolomite, buff and light brownish-gray, fine- and very fine grained, partly arenacous; light-gray and light-yellow chert, much is oolitic, abundant; green shale, sparse; quartz sand, common . Oneota dolomite: Dolomite, buff, fine- and medium-grained; partly oolitic chert, common; quartz sand, common (caving from New Richmond?); iron 1 percent Dolomite, light -brown - gray, mainly fine-grained; chert, common . Chert, light-gray, 80 percent of sample; dolomite, as above . Dolomite, as above; chert, common . Dolomite, light brownishgray, medium-grained; chert, abundant; quartz sand, sparse; iron 1 percent . Dolomite, as above; chert, common; trace of glauconite . Dolomite, light browngray, fine- and mediumgrained; chert, as above Dolomite, light to medium brown-gray, mediumgrained; chert, common; iron -1 percent . Dolomite, as above; chert, abundant; quartz sand, common; iron 1 percent Dolomite, as above; chert, as above, abundant; quartz sand, common; iron 3 percent Dolomite and chert, as above; quartz sand and green shale, common; iron 3 percent.. Dolomite, as above; chert, abundant; quartz sand, common (part is caving); iron +1 percent . Dolomite, as above; chert,common; quartz sand and green shale, sparse; iron -1percent .

Depth (feet) Depth (feet) Prairie du Chien group Continued Oneota dolomite Continued Dolomite, as above; chert, very common; yellow-buff shale and quartz sand (caving?), common; iron -1 percent . Dolomite, as above; chert, as above; quartz sand, as above;iron +2 percent Dolomite, as above; chert, common; quartz sand, as above; iron +1 percent . Dolomite, as above; chert and quartz sand, sparse to common; iron 1 percent . Dolomite, as above; chert and quartz sand, , sparse . Dolomite, as above; green-gray shale, abundant;' trace of glauconite . Dolomite, light- and medium -b rown, medium-grained; shale, as above, common . Dolomite, as above Dolomite, as above; chert, sparse . Dolomite, as above; chert, much is oolitic, very common . Dolomite, as above; chert, very common . Dolomite, as above; a little greenish-gray siltstone; chert, common Dolomite, as above; chert, sparse to common; quartz sand, very common Dolomite, as above, much is arenaceous and oolitic; oolitic chert, common; quartz sand, common; trace of glauconite . Dolomite, as above, most is arenaceous and oolitic; arenaceous and oolitic chert, common; quartz sand, abundant; light-green shale, common Prairie du Chien group Continued Oneota dolomite Continued Dolomite, as above; chert, sparse; quartz sand, abundant; iron 3 percent Sandstone, quartz, fine to coarse-, poorly sorted; dolomite, arenaceous 20 percent of sample., Trempealeau formation: Jordan sandstone member: Sandstone, quartz, fine to coarse, poorly sorted, in part dolomitic cemented Steil 2 Location: Sec. 6, T. 6 N., R. IE., Wis., 245 ft N. 63°30 ft W. from Steil 1. Driller: John Hauser, Mar. 3 to Mar. 16, 1951. Collar elevation: 1,113. 8 ft. Total depth: 325ft. Depth to water: 225 ft. Sample study and logging: Arthur E. .Flint, Mar. 18, [Percentages estimated, except where assay values are indicated] Soil, residual clay, decomposed buff limestone . Platteville formation: McGregor limestone member: Limestone, gray, weathers buff, fine- and mediumgrained, fossiliferous, Pecatonica dolomite member: Dolomite, medium-gray, medium-grained, arenaceous near base . Glenwood shale member: Shale, grayish-green, iron,common Depth (feet) St. Peter sandstone: Sandstone, quartz, rounded; many grains frosted, pitted, medium-fine except coarse in upper 10 feet and mediumcoarse in lower 12 feet Prairie du Chien group: Shakopee dolomite: Shale, light-buff; dolomite, buff, arenaceous; chert, sparse; limonite, common..

Depth (feet) Depth (feet) Prairie du Chien group Continued Shakopee dolomite Continued Dolomite, brown-gray and buff, fine- and medium-grained; chert, much is oolitic, very common; quartz sand (caving), common Dolomite, light-buff, some oolitic, very common; light-gray chert, much is oolitic, 70 percent of sample; glauconitic shale and quartz sand, sparse Dolomite, as above; partly oolitic chert, very common; traces of quartz sand and glauconite Dolomite, as above, some arenaceous; chert, as above, very common; traces of quartz sand and green shale Dolomite, as above; chert, common; iron -1 percent; lead assayed 0. 45 percent New Richmond sandstone(?): Dolomite, as above; chert, common to sparse; shale and quartz sand, common; iron +1 percent; lead assayed 0. 6 percent Oneota dolomite: Dolomite, as above; some chert; traces of glauconite; lead assayed 0. 5 percent Dolomite as above; chert, as above; lead assayed (175 to 1. 25 percent; (177i-180 feet) 1. 20 percent Dolomite, as above, medium-grained; chert, much is oolitic, very common; lead assayed (180 to 182| feet) 0. 5 percent; (182f to 185 feet) 0. 85 percent Dolomite, as above; chert, common; lead 0. 25 percent Dolomite, as above; chert, common; iron -1 percent; trace of lead Dolomite, as above; chert, abundant . Prairie du Chien group Continued Oneota dolomite Continued Dolomite, as above, a little is arenaceous; chert, sparse; trace of glauconite . Dolomite, light-brown, medium-grained; chert, abundant; iron 2 percent; trace of glauconite Dolomite, as above; chert, very abundant; iron 2 percent Dolomite, brown and medium-gray, mediumgrained; chert very abundant; light-gray shale, common; iron 4-1 percent . Dolomite, as above; chert, common Dolomite, gray, mediumgrained; chert, common Dolomite, as above; chert, sparse;trace of zinc . Dolomite, as above; chert, sparse; iron 4-1 percent . Dolomite, as above; trace of chert; iron 1 percent Dolomite and chert, as above;trace of iron . Dolomite and chert, as above; iron 4 percent . Dolomite and chert, as above; iron 3 percent Dolomite, light-gray, granular; chert, sparse; iron 2 percent; trace of zinc . Dolomite, brown-gray, medium-grained; chert, sparse;iron 2 percent . Dolomite, as above; chert, sparse; gray shale, sparse; iron 1 percent . Dolomite, as above; chert, sparse; iron -1 percent; trace of zinc . Dolomite, as above; chert, sparse; some graygreen shale . Dolomite, brown, medium-grained . Dolomite, as above . Dolomite, as above; but partly oolitic and arenaceous; light-brown chert, common . Dolomite, as above; chert, some is oolitic, common; quartz sand, 5 percent of sample; trace of glauconite

Depth (feet) Depth (feet) Prairie du Chien group--Continued Oneota dolomite--Continued Dolomite, as above, much is oolitic, arenaceous, and glauconitic; oolitic and arenaceous chert, very common; quartz sand, 5 percent of sample Dolomite, as above; chert, as above, common; quartz sand 10 percent of sample , Dolomite, brown, arenaceous; chert, as above (caving?), sparse; quartz sand 20 percent of sample Note: Bottom of hole is at or very near the Cambrian-Ordovician boundary. Steil 3 Location: Sec. 6, T. 6 N., R. 1 E., Wis.; 210 ft S. 60° 33 ft E. from Steil 1. Driller: John Hauser, Mar. 16 to Mar. 21, 1951. Collar elevation: 1,103. 7 ft. Total depth: 310ft. Depth to water: 200 ft. Sample study and logging: Arthur E. Flint, Mar. 25, Prairie du Chien group: Oneota(?) dolomite: Shale, light-gray and green; light-brown and gray chert, common; iron,common . Dolomite, light-gray and light-brown, granular; light-brown and white chert, sparse to common; iron 4 percent Dolomite, as above; iron 3 percent Dolomite, as above; chert, sparse; trace of glauconite. . Dolomite, as above; traces of chert and green shale . Dolomite, as above; oolitic chert, common; glauconite, common in dolomite Dolomite, light-brown, arenaceous, oolitic; traces of chert, green shale, and glauconite; quartz sand, sparse . Dolomite, as above, but very arenaceous and glauconitic; oolitic chert, sparse; quartz sand, common; trace of green shale [Percentages estimated] Soil, residual clay and weathered limestone Depth (feet) Platteville formation: McGregor limestone member: Limestone, gray-brown, fine- and medium-grained, fossiliferous Pecatonica dolomite member: Dolomite, medium-gray, weathered, buff, medium - grained Glenwood shale member: Shale, gray-green; phosphatic nodules and iron, common St. Peter sandstone: Sandstone, light-gray and buff, medium-grained, locally medium-coarse; gray-green shale, 150 to 175 feet, abundant, and traces in most samples; bright-red hematite occurs with much of shale; iron common in lowest 3 feet . Steil 4 Location: Sec. 6, T. 6 N., R. IE., Wis.; 710 ft. S. '67° 30 ft E. from Steil 1. Driller: R. Dagenhardt, Apr. 28 to May 4, 1951 Collar elevation: 1,073. 9 ft. Total depth: 230 ft. Depth to water: 155 ft. Sample study and logging: Arthur E. Flint, May 9, [Percentages estimated] Soil and residual clay. Depth (feet) Platteville formation: Pecatonica dolomite member: Dolomite, medium-gray, weathered, buff, medium -grained, some limonite mottling Glenwood shale member: Shale, green; traces of limonite and pyrite; a few quartz sand grains

Depth (feet) Depth (feet) St. Peter sandstone: Sandstone, quartz, light-gray, rounded, some frosting of grains, medium except coarse in upper 5+ feet, lower 7 to 8 feet and in sample 45 to 50 feet. Prairie du Chien group: Shakopee dolomite: Shale, light-buff and green; chert, brown, arenaceous; sandstone, quartz, common (caving?) Dolomite, light-buff, fine-grained; lightgray oolitic chert, abundant; light-buff shale, common (caving); quartz sand (caving), common Dolomite, as above, a little arenaceous; chert, sparse; traces of limonite and glaucoriite; quartz sand, sparse Dolomite, light-brown and buff, fine- and medium-grained; chert, sparse; limonite, glauconite, and quartz sand, as above Dolomite, mediumgray-brown, fine- and medium-grained; chert, sparse Dolomite, as above; light-gray oolitic chert, abundant; quartz sand, common Dolomite, as above, some arenaceous; chert, as above, some oolitic, abundant; green shale, common; a little quartz sand (partly caving) Dolomite, as above, some arenaceous; chert, as above, very common; shale, as above, common Dolomite, as above, some arenaceous; light-gray chert, much is oolitic, very common Prairie du Chien group Continued New Richmond sandstone(?): Dolomite, as above, very arenaceous; shale, as above, common; quartz sand, 10 percent of sample , Oneota dolomite: Dolomite, light-buff and light-brown, fine- and medium grained, a little arenaceous; green shale and quartz sard, sparse Dolomite, as above, some medium-grained; traces of chert, shale, and quartz sand Dolomite, as above; chert, very abundant; trace of iron Dolomite, as above, finland medium-grained; chert as above, very abundant; trace of iron Dolomite, as above; chert, as above, sparse; trace of iron Dolomite, light-gray, medium-grained; chert, as above, common; iron 2 percent Dolomite, as above; chert, very abundant; iron 7 percent Dolomite, light-gray, very dense, fine-grained; chert, as above, common; iron 5 percent Dolomite, brown, mediumgrained; chert, abundant; iron 2 percent Dolomite, light- and medium-gray, mediumgrained; chert, as above, sparse; iron + 1 percent Dolomite, as above, medium-grained; chert, sparse; iron 1 percent Dolomite and chert, as above; iron + 1 percent Dolomite, as above; chert, sparse; iron i percent Dolomite, as above; chert, sparse

Depth (feet) Depth (feet) Prairie du Chien group--Continued Oneota dolomite--Continued Dolomite, gray-brown, medium-grained; chert, common; iron i percent Dolomite, as above; chert, sparse to common; green shale, sparse; quartz sand (caving?), common Dolomite, as above; chert, common Steil 5 Location: Sec. 6, T. 6 N., R. IE., Wis.; 1,475 ft S. 74°32 ft E. from Steil 1. Driller: R. Dagenhardt, May 4 to May 12, 1951. Collar elevation: 1, 070. 7 ft. Total depth: 235 ft. Depth to water: 135 ft. Sample study and logging: Arthur E. Flint, May 14, [Percentages estimated] Soil, residual clay, dolomite sand ... Depth (feet) Platteville formation: Pecatonica dolomite member: Dolomite, buff and gray, medium-grained, arenaceous at base Glenwood shale member: Shale, gray-green; phosphatic nodules, limonite and marcasite, common St. Peter sandstone: Sandstone, quartz, light-gray and buff, medium except coarse near top and base Prairie du Chien group: Shakopee dolomite: Shale, green and lightbuff; light-brown chert and light-brown dolomite, sparse Dolomite, gray-brown-, fine- and mediumgrained; quartz sand (caving), very common Prairie du Chien group Continued Shakopee dolomite Continued Dolomite, as above; brown oolitic chert, very abundant; trace of green shale Dolomite, as above; chert, as above, partly oolitic, abundant; green shale, common; quartz sand, common Dolomite, as above; chert, as above, common; quartz sand, common; iron -1 percent . New Richmond sandstone(?): Dolomite, as above, some is arenaceous; dolomitic quartz sandstone, common; chert, as above, oolitic, abundant; quartz sand 30 percent of sample; iron +1 percent . Oneota dolomite: Dolomite, as above, a little is arenaceous; chert, as above, a little is oolitic, common; brown and green shale, common; quartz sand 5 percent of sample; trace of glauconite . Dolomite, as above; chert, as above, common; traces of green shale and quartz sand . Dolomite, as above; chert, sparse to common; shale and quartz sand, as above . Dolomite, as above; chert, very abundant Dolomite, as above; chert, very abundant . Dolomite, as above, chert, sparse to common . Dolomite, as above; chert, very abundant . Dolomite, as above; chert, sparse to common . Dolomite, brown, fine- and medium-grained; chert, abundant; iron 1 percent . Dolomite, as above; chert, very abundant, iron + 1 percent . Dolomite, as above, mediumgrained; chert, very abundant, iron 1 percent .

Prairie da Chien Continued Oneota dolomite Continued Dolomite, as above; chert, very abundant; iron 1 percent Dolomite, as above; fine- and mediumgrained; chert, very abundant; iron 2 percent Dolomite, as above, medium-grained; chert, sparse to common Dolomite, as above; chert, sparse; iron 1 percent Dolomite, as above; chert, sparse; iron 9 percent Depth (feet) Depth (feet) Prairie du Chien Continued Oneota dolomite Continued Dolomite, gray, mediumgrained; chert, common; quartz sand 25 percent of sample; iron 5'percent Dolomite, as above; inert, sparse to common; quartz sand 25 percent of sample; iron 4 percent Dolomite, as above; chert, common; quartz sand 7 to 8 percent of sample ; iron 2 percent Dolomite, as above; chert, sparse to common; iron 3 percent IHT.-DOP. SET... WASH.. D.C.389J7

UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY PREPARED IN COOPERATION WITH THE WISCONSIN GEOLOGICAL AND NATURAL HISTORY SURVEY CIRCULAR fl PLATE 1 EXPLANATION Om Maquaketa shale Og Galena dolomite Structure contour on top of chert, Galena dolomite Dashed where approximately located Strike and dip of beds Geologic contact, approximately located Strike and dip of joints and strike of vertical joints COUNTY COUNTY Outcrop elevation at top of chert, Galena dolomite Churn-drill hole Drilled by U. S. Geological Survey e: number of hole 733.6: elevation at top of collar 57ft elevation at top of chert

6O5 ,@732.O 6O7 H. H. GHER'S DIGGINGS PROPERTY GAYLOR PROPERTY INDEX MAP SHOWING EXTENT OF PROPERTIES MAP OF THE TETE DES MORTS AREA SHOWING THE LOCATION OF THE HOLES DRILLED BY THE U S. GEOLOGICAL SURVEY DUBUQUE AND JACKSON COUNTIES, IOWA Geology by Alien F Agnew and Arthur E.Flint, 1950

UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY CIRCULAR 231 PLATE 2 Center of east 1/2 sec. 3, T87N., R.4E. 300 feet south to center sec. 3, T.87N.,R.4E. Elevations are in feet, datum is mean sea level '"Drab" (nonc herty) Glass rock1 T.D. 245 FT. EXPLANATION "Clay bed1 rock" Zone containing iron-, iron as sulfide,oxide,or both Shows the estimated percent of iron Zone containing manganese oxide Shows the estimated percent of manganese SCALE IN FEET Total depth Drill hole CROSS SECTIONS OF THE HOLES DRILLED BY THE U.S. GEOLOGICAL SURVEY IN THE TETE DES MORTS AREA DUBUQUE AND JACKSON COUNTIES, IOWA

UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY PREPARED IN COOPERATION WITH THE WISCONSIN GEOLOGICAL AND NATURAL HISTORY SURVEY CIRCULAR 231 PLATE 3 EXPLANATION Galena-Decorah and Platteville formation! undivided Prairie du Chien group Zn.. MANNING DIGGINGS Ogdp Geologic contact Dotted where concealed INDEX MAP SHOWING EXTENT OF PROPERTIES Outcrop elevation at top of St. Peter sandstone Elevation to the nearest foot Churn-drill hole Drilled by the U. S Geological Survey Shows elevation at top of St. Peter sandstone Structure contour on top of St. Peter sandstone HIGHLAN 9O Strike of vertical joints Temporary bench mark and elevation Established by the U. S. Geological Survey Mine shaft G: denotes shaft in Galena1 Decorah, and Platteville formations Zn: denotes zinc; otherwise lead Diggings Zn: denotes zinc; otherwise lead // HORNSNOGGLE ft ..;. :..DIGGINGS MAP OF HIGHLAND AREA SHOWING THE LOCATION OF THE HOLES DRILLED BY THE U. S. GEOLOGICAL SURVEY GRANT AND IOWA COUNTIES, WISCONSIN Geology by Arthur E. Flint, I960 IOOO 3000 Feet

UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY PREPARED IN COOPERATION WITH THE WISCONSIN GEOLOGICAL AND NATURAL HISTORY SURVEY CIRCULAR 231 PLATE 4 WIEST / PROPERTY N 3 corner, sec.6,T6N., R. I E. PROPERTY

/Center SWsec. 29, T.7N., R. IE. Abundant liehert,oolitic chert, oolitic Abundant chert Sparse chert Abundant chert, T.D. oolitic 235 FT Sparse chert II Sparse chert Noncherty, shaly 230 FT. EXPLANATION Abundant flchert,oolitic Arenaceous, oolitic Arenaceous* Uoolitic T.D. T.D. T.D. 325 FT. 350 FT. Zone containing lead sulfide Zone containing iron: iron as sulfide,oxide,or both o eoo SCALE IN FEET Total depth CROSS SECTIONS OF THE HOLES DRILLED BY THE U. S GEOLOGICAL SURVEY IN THE HIGHLAND AREA GRANT AND IOWA COUNTIES, WISCONSIN Geology by Arthur E.Flint, 1951