Portions of Atlin district, British Columbia [microform] : with special reference to lode mining

Cairnes, D. D. (DeLorme Donaldson) · 1913 · Historical

At head of title: Canada. Department of Mines. Geological Survey Branch ..

Public-domain full text preserved in the Mountain Man Mining Library. Original source: archive.org.

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Canada

Department Of Mines Geological Survey Branch

Hon, Hovrat Roars, MINisteer; AU Pp Low, Derery Mistorma;

R. W. Baoen, Diasctros,

MEMOIR No. 37

Portions

ATLIN DISTRICT BRITISH COLUMBIA: WITH SPECIAL REFERENCE TO LODE MINING

By

D. D. Cairnes.

Ottawa Government Printing Bureau

No, 1255

——

gens oO <nmoade

: Canada Department Of Mines Geological Survey Branch

How, Heneet oseas, Minter, A Pp R. W. Baoex, Disactos.

Low, Derere Minseres,

MEMOIR No, 87

Portions

ATLIN DISTRICT BRITISH COLUMBIA: WITH SPECIAL REFERENCE TO LODE MINING

Hy

D. D. Cairnes.

Ottawa Government Printing Bureal

Letter Of Transmittal

Yevver erhierty Peart

D Cairnes

Contents.

INTRODUCTION tiencral ; Location and area ; . Accessibility and tran portation History - General Bibliography SUMMARY AND CONCLUSIONS Topography ‘“% General geology Keonomie geolowy ae Prernore GENERAL CHARACTER OF CTITE DISTRICT Topography i “ ’ General account Regional / ; ‘ ee ee Loval .. Werrrs teenie Detailed topography Relief , The uplands The valleys peasirna rE Hanging relations of tributary valley. Cirques Facetted form. Terraces Drainage

Gimate sc svi ethan Tere rere ee eee BSUDa Nd s MOtt) sais ber ss a oo GENERAL GEOLOGY PP nt Per ee General statement Mena es eer Regional Daa e bee - BOCES eiccsgee Gea Aycorerehees Table of formations

Detailed descriptions of for mations Mt Stevens group nner APE tai eet bec oh Ee

Schistose amphibolites Mashed basic voleanics

Giipiespey..o.7.toe Sericite schists Quartzites Limestone , aaeet Structural relations ,. Age and correlation Tak group. 0. .sc, : Distribution nor Lithologieal characters Age and correlation ..., Braeburn limestones Distribution Gin iscesaacecccc.. ithological characters Age and correlation Perkins group Distribution Bete Nee Lithological characters ;

Andesites and andesitic tuffs

Pane

Vi UEOLOGICAL SURVEY, CANADA

Paa

Ib thase : . Mi Diorite Rey ae es “4 Magnesian rock cies ; wi

Ay ind correlation wi Coast Range intrusives : 7 Distribution Shree Uae waieeceres aa es eee 5? Lithologieal characters - ‘ 57 Age and correlation : AL: ; 4 Laherge series Spices Sates ; wg oe Distribution of apusnedeee. kes 59 Lithologieal characters ; - an Mode of origin , : 61 Ace and corre} ‘tion f2 Tantalus conglom: rate ; 63 Distribution , o Terre dEREWRES Rhee 63 lithological characters fi3 Age and correlation fit Chieftain Hill vole mic 64 Distribution “it lithological characters - . 65 Ave and correlation 8% 66 Klusha intrusives ... x ; “7 Distribution Tr : ‘ . ie ace ‘ 67 Lithologieal characters. ate 67

Age and correlation 3 ? 68 Carmack basalts F - F - AP fis Distribution ae - : 68 Litho’ ‘al character ae ; nm "9

Age and correlation ; ‘ . ea Wheaton River vol nies, ; 7 Distribution ...,, aires , 70 Lithologieal charactors 70

Ace and correlation : ; % 70 Quaternary Pe whi Ae Feweats TNE AEE Oe: 71 Distril ution Os ; : F ‘ 71 Lithological characters ‘ Ee ‘ a 71 ECONOMIC GEOLOGY 7 General ae BaaeN ea esate tie Gale tk Ore deposits ra) Prot we 74

APR eeuaheal ben orae force 74

aie ave cco eas Tt

Pere es Rnkeewacen uy ase Rewer Perce ' 714

BUMMAY i... ac) s, SV RUE See Degen ee hdek 75 Geological formation. 0 7. v5 General characteristios of the veins 75 Mineralization ef ths veins sO Development work Wa aeatargte 81 Values ... daeLuRLAo Rea ae a2 Oxidation and enrichment 0.0.0 83

Origin of the vein S4

The fissures . Sates s4

The fissure-fillings CPs k ah F eg merece Mena fe s&

The Gleaner REORD sce ; Hoe : ee a , 89 General see vcccac Lites ONeae doe cgi waka scans 9 Geological formations rived ”

eUGe Verna. es Cre py ere ; 0 Development , ee ee eer CSTR aaa aga eee ce oat

The Kirtland group...) ie UNROire be a's Ue tented ree 1 Gold-<ilver quartz veins ...00 00 ET Te ee General ..:.., Sine wenn o aciidion piatae alrite hike 92 The White Moose group 93 Grenier une cee ae ete eee ee 93 Geological formations 9!

The veins 93

VELEN DISTRO’, Bee, Vil

Pa

The Rupert group ‘ a General . eskas ot Cieologieal formations ‘ wm Deseriptions of vein ‘ "5 Values ... mire : Hi The Lawsan group ., ?. my General , veunt : e585 my Geological formation wa The veins ee Nackes , "7 Development oi cccccexcuis os Toe wa "9 Other claims on Bighorn creek , ag The [Imperial mines east oF ene 0) Goneral ae ie ny Summary , oa Pi ‘ 100 Geological formations ... Veda ta ; ae De-eription of veins , Ree oP eae i) Values and treatment ; 2% Cann ie Developments 25. sich ieee oe ™ es 109 POH Beteia mine io. car ceeveccnesesecs, sever Saeiteces. TOR Bow lder Mountain claims 2007077" 1a EVISTA Feicceul ceases ncccun mn tbat acon ean Coote 103 The White Star BAGO smarionetiesingresee viene dae tate 2104 The Lake View RIGUB Sri cackie cece: 104 General WBITEB Scents co ten hice oe 1) The Laverdiere group , 0 105 General eR PORMaley eebaens Rus tabipnmacwcamae ¢ 105 MNGCAl¥ine “Clattc ccs ches aceon ee ee Sater eer 105 The Brothon claim ,, ; : Saas ee Cupriferous si VERMUGMVOIRES cic rernes io tar cect eye eee 106 Goneral ... F 106) The Petty group 106 The Dunde group 108 The Pelton group 109 Silver-jead veins fee ws Wales's Cte Neue ea ER 109 General cevscscs.s, Piece ee .. 109

iid

Hi

wer vein MWh

Other veins 12 Origin of the deposits 112 Values in the ores 18 Development 113 Other deposits .. F 113 Copper veing te “ von EH Wt

Ny

11s

Ea}

Goista Sah ea eteck belecer ck eee 193

Cither coal 25 hone MPAKTEA SE Os Cie PO ae Pere ees. baud tine 124

Vib teh OE Cmide Ay SURVEY, CANADA

Illustrations

Photographs

Par PRON TISeIRE? Specimens of gold ore from the Engineer mines, Atlin mining district, BC I. Toke landing F 0 lt. The Coast range in the distance, showir x the strik ne and characteristieally uniform sHmmit: level 16 IV. bLeoking tstward across Taku arm showing a typien! View of the Yukon Platean regior 16 A typical rounded summit south of Graham inlet ” Vv Looking across Takin arm and op Raeine valter toward the Coast range .s 20 Vi Newr view of a typical bortion of plain-like upland 4 VII. Looking northeacter y toward Mt. Stovel,,, ° Vitti Looking easterly aeross Taku arm tow tr Sunday peak ; Mehneie ve ebis cee : IX Near view of a dissected Portion of upland ms Looking eastward across Atlin lake ‘ 29

XI. Looking southwesterly from the summit of Pale

. ; mountain Deri eenees ae. & ieee os 24 XII, Looking westerly toward Mt. ¢ live Saned — pz]

NTH. View of a portion of the Coast ranae just west of Whitemoose mountain ; ‘ .eas 34

XIV Looking easterly across Taku arm, Graham inlet and Atlin lake ; cuepatt ; : 6

XV. Looking up Taku a m from near the Yukon and British Columbia boundary ' 26 XVI. Looking southwest rly toward Golden Gate 28 XVIT. Looking across Taku Arm valley, re Cee 28

XVIT. Typical cirqne on Petterly mountains in the Yukon Platean region ss SREB OTE Te LORS ROTM wees an NIX. Near view of the Coast range, ., ion oaens a0 XN. Looking across the upper end oof Taku arm eee Ge

XXT. Looking northwesterty across the extreme head of Taku arm Eien eRe peered ree oo tee

XXII. Showing a typical wide somewhat heavily timbered depression Vins ialcysangeaenae aoe se RE en . &

NNT. Looking across the valley of Fantail river and along the eastern face of Hale mountain... : +4

XXIV Showing the typical hasaltic jointing of some of the andesitic rocks on Ear mountain P enn ee

: XXV. Looking easterly across Taku arm from Hale moun. tein, showing position of the Engineer mines.. ee

XXVI. Entrance to the tunnel No. 5 at the Ungi DPCRTHIINEN aac por ott ant aes Sone REL TREDL US EAS R2 ‘0 NXVIT. Bunkhouse a cookhouse at the Engineer mine 82 XXVIII. Mill at the E Ane pure hdd a eng Sale ae i 42 XXIX. Looking in a southwe ‘terly direction up Taku arm m1 XXN Looking up the valley of Bighorn creck ; ee:

XXXTI. Photographs of polished specimens of ore from the

central portion of the 30 foot mineralized dyke on

the Big Canyon group. Atlin mining distriet, Be, Wh NNN. Mierephoto raphs of thin sections of ore from the

French claim of the Laverdiere group. on Hoboe

ereek. Atlin mining district, British Columbia... 190

Drawings.

te. 1. Geological seetion south of Golden Gate, showing the platean surface truncating the different reek formations, and ent by the valley of Taku arm... brea 2 Diagram showing the strikes of the veins ac the Er mines, Atlin mining district British Columbia... a)

SPEIN bts pate y hee,

Per an Diagram showing the di Of the veins at the bing titties Atlin minir ¢ district British Columbia wh . ‘ § Diagrammatic ketehes oh WING CPOss sections of typical men hers of the elder Quartz lenses on the Bighorn WaT. ute Bighorn creck, Athin Minto district, British Columbia '" Diagrammatic eet on through the werk ties at the Perrone i! Wittes Atlin mining disteiet, Beaty ht Colnimbia he

Diagrams

Pe 2 Sketeh om ) showing the

geographical it tithe istrict, Berti

tation oof Athi hh Columbia

' 2 The physiographic provinces of Yukon and northern British Columban i The mineral locations in Atlin mining listriet British Columbta Map showing the vein oute rops on the Eugineer mines prop erty, and on the Gleaner eres Po OANtlin omthing distepet British Columbia 7

Map

Noo 12st 44. Preliminary map of Taku Arm, Athi

dlistriet, Bat ap Nove

The abovesmentioned map ots only preliminary Detailed geologieal ane topographical Mitprs

wre it preparation and will be oubli hee later

K

Portions Of

Atlin: District, British Columbia:

With Special Reference To Lode Mining,

D. D. Cairnes,

Introduction. General,

Atlin became known as a Productive phicersgold eamn oa: the svenr ISU, and sine: then a number of ereeks on the emst sid of Atin lake, Within ao radius of 1h or 20 miles froa th Town ot Atlin, have made this one of the more important geld prodding centres in Canada, A number ef quartz elaine, also, Were located during the simmer of tse nd properties of this type have been developed more or Joss from time to time, and, although the attention and efforts of most MPsous Interested in mining in this district live been mainly directed to the placer deposits, Yet ou few PTistien tors and mining-men have continued to prospect for. anil dev lop the non-placer ore deposits, and have succeeded in maintaining a Certain amount of interest and hope and even, at times, enthusi ist, eoneerning lode imining in this district,

Since about 1905 greater attention has been given to the lower Mining industry, partly on account of the promising character of ome of the more recent discoveries on Taku arm and alse dy nM the Atlin placer di posits are known to be slow lv becoming exhausted, and those interested jn the Welfare of the district are vatehieg nore keenly than former! the development. of lode-do ts with the hope that they may continue to fost r the mining industry when the gravels qe longer are profitably exploitable. In 1809 Prof, T. ¢ Gwillim reported on Atlin district: for the Geological Survey af

Canada, and a recommaissanece topographical and geological map

28627 --1

berber te AE SURVEY, CANADA

i Hh) reba be ‘ ' . uw the Seue Pete geecd PEMD when the fieldwork for this repert ated many te porter ah, eoreditiotes poor taining to placer minting have tet tateria tltewerd thie greccbeog thee periave t fitpel Well ttidetetood, but cleweloprrent bea beets tates Pape i othe eae of the other ritterat leg t ft tl district Necordingly the writer was instructed by the Direetor tf the Geolotieal Survey t rake Hee eM GUPPED THe bedt f othe peters

repertant mineral clepersit other than those of ple ergold, in

Atlin cdiatriet, and, ji aedelition. to mah + topowraphical and geal

wiewl survey of a belt ineluding Toki arm from the 60th parallel

th past the head of th vater, thus ineluding the greater numb of the more recently: located quartz: propertios; the following ropert ix the pe of this work which was performed during the summe ef Tote Phe weiter desires to expres stheere thanks for the hearts

ipport received by his party and himself from all those interested Hh tinitese in the cistriet with whom the the bh @onitaet Par timularly ix the writer indebted to Mr. &. AL Fraser, Gold Comeau sioner; Mr. J. Cartmel, Mining Recorder; and Captain James exander, Mr BOG. Nieo', and Mi do Diunibai, owners of the

Engineer Mines, for assistanee rendered and for courtesy extended during the stmaner

Tre the perborriiie tthe work a stall gaseline launch and two cainees Were used for transportation on Taku arm and Atlin lake, wid as these waters are subjeet te frequent and very sudden storm ho cepstate rable Vielen the vusoline lavnel het ouls facilitated the werk ino that the parte was able te travel faster with it than With canoes, but work Was made possible on a considerable number of days when, owing to stormy weather, it would have been iniposatble with eanoes A suitable launeh also obviated mueh of the danger

ithached to this work as such a boat is comparatively safe ino an

of the udden storms that Occur, same of whieh, th four or five minutes, become very diiiwerous for ordinary exnoes, One of th canoes used was fitted with aireompartments along Ge sides and

Was found to be much better adapted to the work than ordinary canoes Which are not safe and should not be emploved ino work of

this deseription on these lakes

Dic re i tet er tent t wl [beets fitete thee pipelie breeh @e pers petebeenyt te gee r a thee teeean H ty Thee " i tt babies i f 4 I he reoatoal the cnet whe ‘ ! rh Ris hh y ed tr her t trie lation Wits extended r the diets ' The topogen is Phi te i rite tt [itierteat ipeus thet t ' WH orestels tied trail re Priaveprsed th ! Pisthatie eany it t lettbeteey reli bewee jievne th tt rf ti of he f tr hatter tritinyt Thy r I Pink Were ‘ with tran ich Peeve denny PELTO Pe sttter fey bh dl HE prem tance of Che were te perforniocd with: appre prteds thy He lex ree of aeeuruey as the ¢ Posraphieul, bet jie © topographical map was a ilobeh he tiell, considerable ditt CULIN Wis eENPePioned is ithe yeete peak ie hetele ote Courbbey eel beak beeoteniedsapde i why i tier that thea wore Her be geeurate! HOWE TpOt a leted topeoxraphionl man Mir. €). ti Cribbins Hos: Mi p Peottert Ih.se itil Mer. Jolin dan ssintend the riter during the entire tele en tel peertorine od the renter part f the ¢ arraphiea! work Mi fribbine alee jasisted iy geology when eipeam fines portiritted Al! J harper their clutie tot =atistaetors reed aitide Micitaters LOCATION AND AREA \rl Pevttadtay ti t itriaterd tre thhe bOrTh Weefery eornies ‘ Brit's Colum bn eon north latitudes 54 I owe (th Beit rotten ul Stet rene totigeituel Mh fe Pbk SO weet of Crreenwieh (Dia ! AT! the mor Hiportant lender cerned I ‘ the district were eNamined bY the we during the <umae f TO, and, in ithe peolowica! and t " raphice! survey was mate ot the weste rh pertion of the traet. or as it is here desic Toko Apim belt. Which embraces a hortherls trending area 45 long and about te tithes wiede This belt inelides all the British Colum pert Pal trey Whiteh

rd ie

4 tH PEPEAMOTO NT, ME RVEY, CANADA

treteds torthwarel, coupe tig a ted preveteie its the afea supvevet

The mapping eovers, ae far ae freteible, the loealithes containing

f

Vieenth trletie ed blauty

hie

Moresby y Us

Soule of mites

Diag. 1. Sketch map showing the geographical situaion of Atlin mining district

promising mineral discoveries, ineluding a number that are shown

on Prof. Gwillim's map of Atlin mining district

STEIN Piette ry, wo o

Jocesstrility And Pransportation

A rail atl atentibenat serv iO! eet Atlin with the Pacif

emit wf Shoapwas Cottitinadin ou femme re — traley resilar CPi pi thirevtigebtescst the tour het ween title nint Shapes Nleska, anal

het ween Vaiectiver steed Shige ¥, eliatanee f LtWe ail "Hh, tettle

Feapeetivels From Skagway the White [', iid Yukon railwa

hes heen Cometrieted te Whitedess e, Yukon, a di tatioe of TEL tithes

From Cariheu.! a peimet ¢ the

" ruilwas OE neni le fren Skagway steadier tmrbos tw. fife aw week te J thu Lavteclinng, wehbe hi that tt) triiles f Carthetu anne js “ittiates! at the eastern end af firahwin inhet, an arm of Taku lal ruilway 2 miles Foti extencbe

from Taku Lan re f

hte —) to a Pont of the weetery shore of Athy

eotteets with the town of Nelin euetern store abe + titles distant NTE peitits

lake, wWhetes HW ete utier ere thie

om Atlin lake and

Taku arm ap this directly eonthected by pail and stemrileatt service

with Skugway

Wageoteronds have heen constructed from Atlin up Pine wnd

Spruce Cheeks and their HiOPe Tipeorcune tribitarios

tiles tip Fourth

tratts have been made up Pike river, Mi Ke ereck, and other Impertunt strearys

ofsluly er Ok! Roads

on the east side of Atlin lake

built from Kirtland on the west side of Taku arm to the lode-diseoverios on

A Wregrerpe roud his Alen hens ti Bighorn creek, apa rete have Workitivs at the Engineer mines and Gleaner group with the eit shore of Taku arm

heen constructed connecting the

During the winter “eon aostage runs regularly between ¢

cross and Atlin—a great part of the

ar

Journey being made on the jee:

in the late and early Witter, just before navigation is open and after

it closes, while the ies Is Uncertain, dog-teams carry the mail

hetween these point.

HISTORY General.

Atlin became known itm prod etive

placer camp within a few months of the date of the

discoveries tiade hy Miller and MeLaren

on Pine creek in January of the year 1898, These men made the

‘Originally known as Caribou Crossing,

but now called Car rows hy the Post Office authorities and Car

hou by the railway people

ths wr

eye eae

several tthewer

These British Columbia

figures are

i P eh thee vt f ' + ' j t ' ' no oin bts , . wh) ' meet ite mine tir t weitere ' beset @bt eum , ihe PM et rn © tb tities j TT shit pe ' rel Pelewt phi Teal rail f i shert tr fur ct hs fret Shagway ‘ che peeere® peony bouta red th fia Tin 1 reotite i fren Dae fit Freer ft thee treeth ee r Malt sioibeiperts Vorble itiel or fivicle at PP Felewraph- Te itriatl e ‘ i ill er ruph ‘Pestin tra trett: Colehorat f ward Neh tal Bibliography teputiipe opecrnel Thateret t th ter of M Hritieh ¢ mW m ft ; I ist ued (oom ner at Ath for the " m the re rt f ¢i M VI

Ltt tT

rway

tt

Thin DIS THIGH. &. 4

el others COUEAIE reports vo the Provineral Mitieralowist i ctedel Hoot the ESO volume: shore reports appear by Prof. 4d.) Gwillin qiavte: Heo Low Prot, Cowillin is al Miplosed th (i ‘ Suirye f Canidae in tl listriet hurting the ities of ES cael PMO eed Report on the Attn Minin District h 1 ‘ ih hitb teed Teopre 2rapl If thet wevlourte il thaape Lea oloade ihitery tients tilabole ae eorpinuw the thief up hint fates Whe ! it onOns concerning Nt ly

strict Aelittud ehiopt t tle Vln Gold Con

HiISstotiet

Robertson, Wo Provincial M neralogist), Reports of th

Minister of Mines, PSUS, pp. Sos LOO, pp. CO5-T7O ped Pp. Abies Lowry, RoC, Report of the Mini teroot Mines, Boel. bse, iu

H.C. Report of the Minister of Mines, Bae, ISS),

(wel, Survey of Can. Ann Rep. Vol NER rae, pp. O2A tOA,

“Report on the Atlin mining distriet, British Columbia, Geol, Survey vof Can. Ann Rep. Vol. XI, Pt B Ist

(teot, Survey of Can. Ann Rep. Vol NEE, 100, pp 5ZA-G2A

Notes am Atiin gold Hells.” our Can Min. Trest Pha, pp. f7-bog

Characteristies of Atlin wold helds,” Jour. Can, Min. Inet 102, pp. 21-35,

Young, Rosalind W.. Mining i Atlin,

Jour Can. Min. Tust.. Pan, yy ATT dd

British Columbia,”

Caines, Dy De Canuihinn tllirium-containing ores do

Can. Min. ., Ht, pp. i2-1og,

‘Portions of Atlin distrier, Bae litt. Rem: Geol sarc v,

Dept of Mines Lite, pp. 27-40,

be} GChOLOGICAL SURVEY, CANADA

Summary And Conclusions. Topography.

Taku Arm belt is a northerly trending area about 45 miles long by 16 miles wide. in which Taku arm occupies a median position, and vets as the main drainage chaunel of the district. ALL the streams of the arca empty inte this arm and their water tlows thenes through ‘Tagish and Marsh lakes, and Lewes and Yukon rivers te the Aretie ocean,

The belt lies. for the greater part, in the Yukon Plateau pro

Vinee, bot to the south it includes a portion of the eastern edge of the

Coust range. Thus two contrasting types of topography oecur in the distriet. The Yukon plateau is an extensively dissecte and

eroded plateau, in parts of which almost ne trace of the original Upland remains, and the topography consists of irregular'y dis- tributed rounded hills whose summits may or may not ric te a somewhat uniform elevation; in other localities, however, nimerous Hat-topped interstream areas of uniform heie tain. The valleys are everywhere wide, deep, steepewalled, ivpicatly U-shaped depres: sions.

The Coast range is extremely rugged, consisting mainly of knife- ike ridges, needle-summits, and abruptly incised valleys, and every- Where considerable ice and snow are to be seen throughout the entire year.

These two physiographic provinces are believed to have been Planated to a mature stage and the Plateau region and possibly the Coast range as well, are considered to have been peneplanated. Subsequently these terranes were uplifted, apparently 8.000 te 4,000 feet, the movement being greatest along the axis of the Coast range. and least along the central portions of the Yukon Plateau region. The streams were thus rejuvenated, and soon entrenched deep V- shaped valleys in the uplifted surface. Glacial ice then invaded the district and occupied all the main depressions whieh were both widened and deepened and given U shaped cross-sections, and sueh

well known forms as cirques, hanging-vallevs, roehes mouton-

tiles Jong position, All the vs thenes

rivers to

uth pre re ol the our int ete and original arly dis- fio TO 8 bi nerous © valleys

depres-

of knife- il every-

he entire

we been possibly planated. to 4.004) range. 1 region, deep V- aded the ‘re both ind such

mouton-

ATLIN DIStRIOT, be,

Hees, poteholed valley floars, ete. were produced, Morainal and other glacial material were leposited ji the Hew bottoms, aa ive per diced reversed leapres in nest of the miin valleys CUtistiign the iter te be damned above, in the form of lakes Pawish lake. is

Paku arm, and Racine, Tut hi, Fantail Edgar. and Ne

have all been caused in this way and represent the positie

HCeupies by the last tengues of the retreating dee. which melted rapidly toward the last, that the depression= ther eceupled had net time te become tilled with detrital materia

The wide difference between th topography of the Coast ran

ure and that of the Yukon plateau seems to be cue mainly ote thre Cillises, In the first place . the Coast ratige is composed largely aft

Hatssive granitie rocks whieh do net possess bedaing planes, ues

alternating hard and soft layers te te emphasized by erosion, so that

sub-aerial agencies have had ne reg Har control and have thus pre duecd very erratic terms. The Irregular jointing plains in the rocks have also in places assisted in the production of bold, irregular topographic forms. Secondly, those granitic recks are generall harder and in mest places erode less rapidly than the socks of the

platean and, therefore, have caused the Coast range in this distriet

to retain a greater genoral e'evation than the region to the east Thirdly, sinee, for various reasons Invelving differential erosion and plift, the Coast range is now higher than the Plateau region, it

“tll contains glacial ice although the glaciers have long ago vanished

g from the plateau region. The glacial ie continues te wee atuate t features of the Coast range, whereas in the plateau orovinee, “Ince its retreat. nivation has been aetive in the uplands smoothing over inequalities, Thus once a line of demarcation was established between these two terranes, their features have steadily become more anid more contrasted,

General Geology,

The extreme northern and southeastern portions

of Tak Arm belt are included in the Coast range and consist of Coast Range granitic rocks whieh are mainly grevish, coarsely textured grano- diorites. The remainder of the area extends well out in the Yukon

Leo

Plateau region and contains a considerable variety of

oLlcal

10 Upologloal Survey, Canada

formations whieh range in age from lower Pahoosaie or older to Reeent, and inelude igneous and sedimentary members as well certain metamorphie roeks of obseure origin

The oldest roeks consist of a group of pre-Devonian selistose nd gneissoid members as well as some limestone bands, These have been invaded by and, in places, extensively buried under a wide-spread Eroup of Devonian (4) andesites, andesitt tuts, diabase, diorite, ond magnesite. Dring Devono-Carboniferous time seve ral thousand feet of sediments aeeanulated, whieh are now limestones, slates und possibly ehorts. ‘The cherts are of somewhat obseure origin, ane oceur in only a few small areas. but ure everywhere aasociated with the slates The limestones are very extensive and have an augregate thickness of at least 5,000 feet.

Overlying the limestones, the more recent of the Deyono-Cur boniferous rocks, are Jura-Cretaceous conglomerates, sandstones shales, greywaehes, tutfs, slates, and quartzites, having a thickness inh places, of over 5,000) feet,

Phe Coast Range granitic intiasives that compose the Coast range and if=o form dykes, stocks, ete, in the Yukon PI iu region, are in inost places, greyish, coarsely textured, sranodioniics, and are generally deseribed as having been intruded in Jurassic time. The evidence obtained in Taku Arm belt, however, shows that thes were intruded during ditherent, and widely separated periods, some before and some after the deposition of the Jura-Cretaceous sediments.

The J

intrusives, as well as the various rocks of the district older than

wa-Cretaceous sediments and the Coast Range granitic

these, have been pierced by various voleanies and in places have bean covered oy a considerable thickness of lavas and ussociated tufaceous accumulations, These volcanics range in uge from late Cretaceous or carly fertiary to Pleistocene and inelude andesites, andesitic tufts, granite-porphyry, basalts, basalt tuffs, rhyolites, and rhivolitie tutfs. Overlying all the consolidated geological terranes of the district are Pleistocene and Recent accumulations, consisting chiefly of gravels, sands, ‘lays, silts, muck, peat, and soil, whieh deeply floor the main valley bottoms and also extend well up the side hills and in’ places even cecur abundantly on the uplands and

mountain summits.

VELIN Dis thier, py Li

hOCONOMIC GEOLOGY

Vhe seetion of this Hheetioie led

ling with CTO weolowy tas referen to the entire Atlin mining distrie t, ated this differs £1 the other parts of the ae mor, Whieh refer only to the weet rho peor trom oof the pen. ar it is here designated. ‘Paty Aron belt The various deposits of economieally in wortinit faineras li that placer gold th whieh this temeoie fot copeernped that eeatr in Athin neiming distrier hia tentative lassitionl a

Hows LOI DEPOSEys (¢) CGiold-telluricm quartz vein (6) Cold-silver quartz veins (6) Cuprifereu silver-nroda ils (2) Silver-leud vets (6) Copper veins (7) Amtitnous vets

(0) Contaet-imetatmerphic deposits

H.—CoAL.

Gold-tellurium veins have been found in only one locality. whieh Is sttuated on the west side of Taku arm above Golden Gate, at the Engineer mines and adjoining chtims, and mueh the piehest ores discovered in Atlin mining distriet: have heen obtained fron these properties, The discovery at the Engineer mines of a number (t pockets of quartz worth from #8} te 85 per pound, caused raueh

excitement during the summer of 1910, and had a decided effoet in

arousing enthusiasm in lode-anining. The most wide-spread group of deposits are the gold-silver veins which are found in a number

of localities scattered over the greater part of the distriet. Cupri ferous silver-gold veins have been found only on Table mountain. and only one vein wort! noting has been discovered. A number of strong. well-mineralized veins belonging to the silver-lead division scour on Crater creek and in that vicinity. Copper veins have been found only on the southern end of Copper island, and those far discovered do not appear to be of ap present economic value. Ont

antimony vein is known to occur in the district: it outerops on the

west shore of Taku arin 10° miles below Go'den Gate, but as th

12 GCRhOLOGIOAL StRVEY, CANADA

tlepomit lias been exposed for only about BS feet vers little is kiown coneerting jt Contaet-tetameorphic deposits, so far ue is Kerner ray

eccur only on Pobee creek meur the poer ent of Torres ehannu

und sinee they follow aw single e Htaet, it tay be better te consider thom as a siturle deposit, as there is nothing te indieate that the or does not follow the contuet eoutintiotsty between the points where its oulterats biave been eheountered Vhe ore beuly, whieh CUS ists largely of Hebi fe CAPreN iti Vurwitige otitis of Copper, exeools feet in thickness everywhere ii has been exposed, and is at one Pent LOO tect in thickness, Outerops have been discovers 1 throtih out a distanes of S000 feet or more alone the conuer,

No coal seams in place have been found, but Tantalus eotinle merate, Which is always associated with eonts in southern Yukon, ceetrs ait several points, and a considerable amount. of flout coal has been found te the horthesast of the lower end of Sloke lake where the seams from whieh this is de rived should easily be found

A considerable number of the mineral deposits occur along the shores of Taku arm and have thus direct boat connexion with the railway at Carcross, Most of the other occurrences ure on, or within

short distunces of navigab'e waters. an! are fur from the rail

Way, In couneXion with the utilization of these ores an orde r at the railway commission in 110, that the freight rates charged by the White Pass and Yukon railway on ores, shall not exeeed R175 per ton from Caribou (Careross) to Skagway, is of importance since the ores and concentrates can be sent by boat directly from Skagway to the various coast: smelters,

In conclusion, it may be said, that Atlin mining distriet pos- sesses quite a variety of economically valuable minerals whieh oeeup in places in deposits of considerable size, and that in some of the mineral veitus, pockets of xceptionelly rich gold ore have been found; also that practically all the deposits are readily accessible. The lode-mining industry in the distriet has made a good beginning: and Will probably continue te develop in the future. The results up to the present are particularly encouraging when it is remembered that since 1808, when mining commenced in the district, nearly all persons engaged in this industry have devoted practically all their attention to the gold-bearing gravels, and that. until verv. rece ntly,

there has heen a relatively slight amount of prospecting for quartz.

VEEIN DistRier, nee, Lu

General Character Of The District Lopograptes

General Account.

Kt HN AL

The greater pert of northern British Columb tand Yukon Ter

Fitery may be broadly divided inte three PUNSstographic provitiens

Which persist southedsterls through British Columbia, and to the westward through Alaska Named in order from southwest to north

eust, these provinces ares the ¢ oustul system, the Interior “Veter,

and the Rocky Mountain svstem These terranes Cotstitute the

Cordillera of northwestern North Aimeriea, and follow in a general

Way the peculiar concave contour of the Pacific coast line They thus

all trend northweste rly through British ¢ columbia, strike in a Westerly

direction through Alaska. and in Yukon, in between. they follow an intermediate course, Lying to the ne rth, northeast, and east of the Roeky Mountain “Ystem ure plains or lowland tracts—the Aretie Slope region, the Mackenzie lowlands, and the Great Plains (Diag. 2.),

The Yukon Plateau province constitutes the entire Interior aya tem in Yukon and in northern British Columbia southeastward to about latitude 58°, whence for thout four degrees of latitude the Peston is oun tanous and Consists, according to Dawson,’ of disturbed Cretaceous rocks. Beyond this mountainous portion of the Interior system the surface gradually declines to the upland of the Interior plateau, which continues southeasterly. to a point a few miles of the 4th parallel?

From about the 50th to near the 60th parallel, the coastal avatem

south

embraces only the Coast range. if the islands to the West be eon.

sidered to form part of a ~eparate range? but the simplicity of this

' Dawson, G. M “Geological record of the Rocky Mountain region oon Canada”; Geol, Soe, of Amer., Vol. 12, p. 61.

Daly, ROA, “The nomenclature of the North American cordillera hetween the 47th and 53rd parallels of latitude,” Geog, Jour., June, 105, Pp. OS8,

Dawson has separated the Vancouver range from the Coast range, See: Dawson, G. Mo. Trans. Roval Soe. of Can., 1890, Vols, See. 4, D:.

Geol, Soc, of Amer., Vol. 12, pp. 61, 62

‘ he 2

rf ; fe)

- — oe 5 ; - 3 - : gS: - io : So 3 SS Oe Sond - : a F a rt ae eae Ig¢é a - zs ‘ Gaze s eS &. res 2 : I ma oS: - es - + - - - 3 7 E

r. Be 2 mW beovelithute 4 i ‘ Thee t Patras er fe wit ‘ t titte fps thee Ihe h ¢ tabi t weer thre Peeegeed ! teal. y behind St. Elias range. and fer the Prertaited ta eHifee forth pil ti trit tile ttheeset eaeter portion tty tetal " thet of Tass brat the rary Pistisally beceevrnic he ! teiteent Here tte the Yukon platen tewe Dake Khiane, at batinuds St and longitude Iss ge Phe ¢ i h ‘ ' jo wenere toate arregrulae Hiplen ed prey se wiedpes, thiat press but little svinmetry other Chetty ot pevcale sabieeetpenet perallel te a nerthw ster y-tretudin iN} The range has ever vhiere

b precipitous knite-edged epost Hits. and sharply incised valleys.

and jagged aspeet, and eo t larwely of

even needle-like The stmimits

rigged. or suit sottthern Pritial

Columbia rise te uniform altitudes of from SAM te OOD fot

ea-level, but to the north they medtduntly deepejise

in Yukon stand at only 5,000 te 6.000 feet hh altitude,

above nel

eVation, an

above the seu, This chang: Is wo gradual that it does not break ‘pPorent uniformity of summit-elevel whieh.

though reat,

the

owever, bears no pela

Hon te structural features. This te rrane has thus been eon idlered by a number of geolog Vio have st

Pep Powe nt

died it topographically, to re heplat atod

thature te ob stirfiuce of vated (Plate IP)

Phe Yukon Plateau pre

ro at least a erosion,

subsecque ntly le

thee stretches freer the the Coastal system to the

“oof the Roeky

iti tiered Pitignes af the dork parallel of latitude (the Y

Trhotitituites ukon-Britiah ¢ olumbia In northern British Col

iid, Tiewy

woutidary ), Is 250 to S00 miles wide imbia some well defined ranges lie within this region,* and in Yukon and Alaska mat single peaks and miner

iy rittiges ri

se above the platea below Dawson, G. M E Report B.C.” Ann Rep., Geol, Sury

on the area of the Hayes, C. W., “An

i Kemloop Hap shew of Can., Vol, Vil, Ist,

t p 10K expedition through Yukon distriet,”"” Nat. Gy he Mag., Vol, 4, p. 128. Spencer, A. C., Bull, Geel. Sox of Amer., Vol It, p. 12 Brooks, A. HL, “Geography and No,

$5, Pp. 286-200,297, “Dawson, G Mountain

Cieology of Aloska.’

S. Geol, Survey.

M., ‘On the region in py. 4, 5.

Prof. Paper

later physiographical geology of the Roeky Canada,” Trans, Royal Soc, of Can., Vol. 8, Se 1 Portymile atlas sheet, U.S. Geel Survey Spurr, J. E., “Reconnnissance in southwest rm (reol, Survey, pt

iA VII, 1898-99, pp. Bas-o4o

ho.” 20th Ann, Rep

he GEOLOGICAL SURVEY, CANADA

Pita t prloetet fier thy eee Yueh rrich tevethern PHertich ‘ " the thee lraite t have iterme channels varying r i BRE Fog pth, thie proahweing a very bere rf t h I hie fitter f this trent he ohi tiet erly tt f i tere hae why ¥ ve plate whrbely sberpe t rel this th tel reevetl t Phe phitests. seen frons a stent tt al le a it the level of the tplaned, wil tiptoe the ob ever ith tee ti ithe Veep tT ter three beevpi +. ttl bepekeet i bhevt iteel thhert ttesd, pesetebtiaey trraewe that whee alan tl ' ral level I plate, however Cut. the fed tee ri rr eres bet itig beowedleud ¢ ipturie of tho hard + well Te striate in faet, ite surface bs entirety cbbeeordare te the highly eomtorted, motamorphie pocks that Heetkkes tape teetierl the polate ih, os ts miore fully clisewesedd later, be evidently in ftevl satech ebbsweceteed perepelate prodiiowd by long-eontinuedl ub rial er th cbtering a period of erustal atabitits (Plate TEP)

\long the gorthern portion of the Coast pan e, the general stnreipenet fee ewe ite that of the Yukon plateau, fie a tater Mutesting the syuebpogou puitation’ of theme twee provinees, vit that ts held by Brooks, Speneer, and others: but luring th VarPiortl Vertiong: tevemenuts that have atfeets 1 threw rrities, the

HEE Has beon greatest along the axis of the Coust range and least

thong that of the Yukon Plateau provines, which terrane is thus

en the contour of a huge thoring trough whose median line

mow general way, marked by the present position of Yukon river

from teste ite howdwaters in northern Beit Coluiwbia te Bering

Arn obelt, whieh was sureewed during Do pO,

! er part Witt in othe western part oof the region, but also extends a short distance Miter the

ust rane Phere, wo distinet line of ch mMareation indicat tf

boundary between the plateau and mountain provinees; these, i

oeach other, so that a transition belt oer urs, general!

frome - ote b miles wile, in which many of the points eannot

vtinitely be said to belong to either terrane

Speneer, A. C., Bull. Geol, Soe, o Brook A. H Cieowrapl thief No. $5, pp, 286-200, van ToS

f Amer, Vol. 16, p. ie geology of Alaska Prot Paps

RO PU wey 4 OB AINE? pee tere

25 Hui Iemays anuergs 7 eu

ee

ATLIN DISTRICT, Bc, 17

Lema

Phe portion of Atlin district - irveyed during the simmer of 1910, 43 previously mentioned, is a northerhs trending belt that extends about equal distances on both sides of Paki arm from the oth perallel south to past the Upper end of this water, and ineludes th

portion of Atlin lake. Sinee the main physiographic terranes i northern. Jortish Columbia trend northwesterly, and Taku arm ruus almest due north, the southern portion of the area mapped

budes part of the Coast range, while the northern limit reaches Wea vce inty the Yukon Plateau region (Diag. 2). The transition from the plateau to the mountain portions of Atlin district is very gradual, so much so, that it is, in places, difficult to determine where ene ends and the other begins.

The plateau topography is characterized by two striking fea- tures, the numerous, irregwarly-distributed, wide, deep, steep-walled valleys, and the elevated and in Places slightly undulating, juter valley, upland areas, The upland-surfaces jn spite of dissection aii eros are in muy pl Ces extensively preserved, and there, as els Where in the Yukon plateau, bear no relation to rock struc tures, but, instead, the sandstones, shales, granites, schists, lime- stones, voleanics, ete,, have been truneated, regardless of their respective degrees of hardness, structural features, ete. (Fig. 1)

Standing on one of these Upland tracts, well back from the edges of any valley-wall, and so situated that his field of vision includ s the uplands and not the deeply trenched valleys, an observer sees these areas as portions of one plain, and it is easy to pleture it a continuous undissected surface, as it once probably was. The topo graphy, as seen from such a viewpoint, has buat slight relief, and obviously was produced by a long continued period of erosion, at the end of which a mature te old stage in the physiographie eyele was reached. Nearer the edges of the present depressions, topographic uncontormities are everywhere in evidenes at the intersection of the abrupt valley-walls with th plateau-surface. Near the lower end of Taku arm the upland is approximately 3,300 feet above the lake level, or 5,460 feet above the sea, and towards the southern end of the arm the plateau-surface is somewhat higher.

Oceasional hills rise above the general level, and represent the

28627—2

Canada

Survey,

Geological

@D —

LIT NEE] yo Aaya @

Pics

oot

000%

Ag 3N9 PUP SUONRUWIOY 404 JUaZAYIP OY) buNrouns Bons Nrazr}d ayy Hulmoys ‘eJED UEPlOL) JO YWNOS UONVES jROIHO}OeL) By

] 000986. 7 35 2M

Itt)

nee af PY¥D/

VILIN DISPRICT, By ©, Li

only considerable masses that the aneient rosive agenvies left stand ina above the old plain like SUrtiiee, erosion having been interrupted before the work of destruetion was completed. Mt. Clie and Sunday peak are notable Satnplos of such mountain remnants

Over considerable Portions of the district, the Pliteau SUrtaee lias been almost if not quite destroyed by later erosis ny, and in suel places the topography consists of irregularly-distributed, rounded hills, many of them gently Contoured and with summits hat are many cases remarkably uniform in el vation (Plate LV).

The principal valley in the district is that occupied by Taku irm, the upper 45 miles ot Which lie in British Columbia, The arm is int most places from 14 to 2 miles wide, but the entire Valley bottom has, in places, a width of as much as 4 miles. At its upper or southern end, the arm turns abruntly to the West, the southward continuation of the main depression being vecupied by Hale creek und Edgar and Nelson lakes,

Numerous cross-valleys Join the main Taku Arm valley, +

u the lurger of which lakes and their outlet streams, or arms and inlers of Taku arm occur, the more important of whieh are Graham inlet, Valaha bay, Tutshi lake and river, Racine lake and river (Plate V), and Fantail lake and river, All these valleys are U shaped, deen, wide, and steep-walled. The streams joining these larger drainagy channels almost invariably have hanging valleys, and the smaller the stream the higher its valley is hanging above that of the larger depressions.

Towards the south and west the surface of the Yukon plateau adually rises and becomes more and more dissected, and the topo ofaphy consequently assumes an increasingly rugged aspect until the Coast range is reached, whieh is charaeterized by knife-edged crests, needle-summits, and sharply-ineised valleys. In the precipi- tous valley-walls numerous ice-masses nestle and the ice increases in amount southwestward until, a few miles above Atlin lake and Taku arm, the great Llewellyn glacier is encountered, which oyer- rides all except the loftier peaks and spurs. Sometime subsequent to the deposition of the Jura-Cretaceous beds—the most recent of the consolidated sediments in the district

the tract now included in the Yukon Plateau region of southern

20 Geological Survey, Canada

Yukon and northern British Columbia, was apparently subjected, a already indieated, to a long period of sub-aerial erosion which con tinued until a plane-like surfae resulted, having an elevation slightly above that of the sea, and with only oveasional residuary peaks and ridges rising above the general level; from the attainment of these results it may be inferred that the land during this time remained in a state of almost perfect stability, This erosion-eycle wae .erminated by a gradual uplift of the Yukon Plateau region tovether with adjoining portions, at least, of the Coast range, Erosive processes thus received hew life and energy, causing the streams to rapidly entrench their channels in the elevated terrane, The effects of ‘tream action, in this respect, Were later accentuated by glaciativ... The main ice-masses occupied the master-depressiona such as that of Taku arm, and both straightened and planed their slopes, and widened and lowered their floors, ‘The valleys thus produce ] were wide, deep, and steep-sided. The ice also acted in a constructional eapacity and eaused the valleys, in places, te become floored to considerable depths with giacial silts. sands, gravels, boulder-clays, ete. The formation of such lakes as Taku arm ond Tutshi lake, which now occupy the portions of the valley-bottoms that were last occupied by these glaciers, is owing to the fact that the ice retreated up the valleys so rapidly that only the lower portions were filléd with glacial debris, causing reversed slopes and effectually impounding the water abeve.

In t'e present plateau-region the only representatives of the former glaciers are the few small iee-masses that still oceupy ocea- sional cirques; so that in the uplands nivation’ or snow-drift action has been at work and has tended to smooth over inequalities in the land-surface rather than aecentuate them. In the Coast Range region, however, on account of its higher altitudes, the ice is still abundantly present and cirques on opposite sides of the ridges

and around the summits are being exeavated downward and bhaeck-

? Nivation in its different phases, relations, results, ete., is discussed in the two following articles

Mathes, F. E., Glacial sculpture of the Bighorn Mts.,” Wyo., U.S Geol. Surv., 2ist Ann. Rep., Pt. IT 7° ‘%, pp. 173-190.

Hobbs, W. M., “Cycle of mountain glaciation,’ Geog. Jour., Feb., 110, pp. 147-163,

Plate IV

28627—p. 20,

e portions of the

of considerat

ans ate characterist

‘egion

Such mount.

summit south of Graham inlet.

ded

A typical r

Yukon Plateau r

SURE SOD ou PsEMOY ‘AayjEA ou 8 Gn pur wie Nye) ssoude furyoo

' ‘ ‘ Zt ‘ t ' I t ! xegenl j eet ' Detailed Topography ] 1 Over port Ta Nr f Piitewu ¢ i an eute ohwe eriat ire iff I rvecd, andy reel Pitarin Fovabten that r i ' i trletect PHGEEER LER poste f rial erosive hi t lente the hel ie fines Hhak tel Diveeteivs " tite Hered thet tiple these plat NiMea eit aiih tl} ' irfa oastbl everal miles over bar i taf ' fated about S400 te S500 feet aheve the lewed Paku hag Vio Over consicerabl portions of the diatriet, et the tr the former iplarel remains aed the fopomrapl eon t if routed hiils, many of th minits of whieh 4 f ition of the plate wu trtie fit pla t i eeewded: po per the plateau rhe tired tel coal hi Preguiner ty remain Whieh show n conecordanes it tren level (Plate Vil the (ois? Partie plateste fragt if tl ine or Pare irrewe ite theoviee Vere hie ted ty l i \rin helt Phe Peateai surface te be observed to the hest advantag ist he hwo from: fiterstrenmn prottits, ttttedd sen istiunies from the edges of the ama fer ible from eh positions the eve gently rolling character of the plateau is <triking! ppurent rh irface bears no relation to reek structure iid the pee Dy bist Htorted schist id gneisses, the JuraCretaecous tuff Warekes, sandstones, shales. and contlomernts nil the : thie re wil tritmeated, romapdle f their striet ire, lua position or other qualities fe generally rounded, summits as those of Mt. Clive. and Sunday peak, are the onhs tt =peuat elevations ri ing above the were ral level

ny

The plateau surtice ¢

hus re presents

plain of erosion tl

been produ ed rains h ord rar. OPresive tVehrey

rodueed by ghaedat

kotehation,

if it has heey

a. as

Ical Burvey, Canada

flace would be everywhere atrewn with foreign giacial materials, which ia, getierally, not the eam In places there is evidences such aa the ook urrenes f atria and erraties, that ice haa moved over the

plateau surface, but the greater part of the upland ia covered with local material pratueed by ormlinary erosive ard weathering agencies

This plateau surface thus appears to form part of a region that during a long period of crustal stability was alimost completely base-levelled, and waa reduced te a condition of dd age, At the titne of planation the Taku Arm uplatel must thus have formed a portion

of a plain the edge of which Was at or nearly at se level Phe

reaidual mountains that now constilute thotiadnoeks Fieitty above the plateau level, represcat the only considerable elevations that fetnained to break the monotony of the former landseape Base levelling processes, which tended to reduce the entire plateau region to sea-level, were interrupted, before the reduction of these remaining hills, by an uplift whieh affected a great portion, at least, of British Columbia and Yukon

The time during which this planation oeeurred, as well us the date of the subsequent uplift, are sotrmewhat in ceubt Phe ev dence obtainable in Taku Arm belt showa only that some time after the intrusion of the Coast Range batholith, whieh is thought to have occurred in Jurassic times, and also after the Jura-Cretaceous Laberge beds were dep sited and aomew hat defortn d, thi porti th of the Yukon plateau, as well possibly as the adjoining portions of the Coast range, were reduced to a contition of but slight relief and that subsequently, but in preglacial time this district was uplifted to about ita present position in pre-glacial time Investigations Is different geologists in various pertions of the Yukon plateau and neighbouring terratse ndieate. however, as described under “Gener il Geology,” that this planation occurred during Eocene, or pre-Pliocene post Eocene time, and that the planated tract waa subses up lifted during the late Mioeene, Phoeene, or early Pleistocene epox h

The amount of uplift is also somewhat indefinite Taku arm

about 2.160 feet above sea-level, and Lewes and Yukon rivers, whieh earry thi# water to the sea, have grades much in excess of rivers traversing a distriet in ita old age Further, if seems very improbable that the area prior te uplift, wa drained by a longer

water avatem than the present eirenitous one: in fact, investigations

atte fted

ated eral sone

wer

ions

Pune vi

Pate Vill

Looking easterly across Taku arm toward Sunday peak, which is prominently shown in

the centre of the view. This is one of the typical, rounded, isolated mountains that characterize portions of the Yukon Plateau region.

Pap SwPesjS jews 94} JO SAajen Gulbuey 19e)6-u0u ‘pedeus A dueys 94} Suimoys ‘puejdn J0 UONL0d paessip e JO MOIA

4Pon

"Yt MPid

blate x

Looking eastward across Atlin lake, she

owing a typical view of the district to the east 23627 —p.

ATLIN DISTRICT, B.C. 2c

have tended to show that the district was drained into the Pacitie by a much shorter system,! The Beneral surface of Taku Arm belt was thus probably less than 2,160 feet above sea-level, when the uplift commenced, while now the upland has an average elevation of about 5,700 feet. The vertical extent of the movement was, therefore, greater than the difference between 5,700 and 2,160 or B40 feet: and probably was 1,700 tr 5,200 feet,

When the Yukon Plateau region of northern British Columbia and southern Yukon was uplifted at the beginning of the present erosive cycle, it assumed the form of a broad, shallow trough the sides of which sloped downward toward a median line, The results of this differential lift are well illustrated in the Taku Arm belt where the upland surface inclines upward toward the southwest and gradually riges until the level of the Coast Range summits is reached (Plate XI).

The majority of Canadian and United States geologists, in cluding Brooks, Spencer, and Dawson, who have studied the Coast range, vonsider that it also represents a peneplanated and subse- quently uplifted surface, and Brooks, Spencer, and others are con- vinced that the Coast range and Yukon plateau were ayn- chronously planated and uplifted. MeConnell on the other hand maintains that the Coast range, where examined by him, shows no evidence of ever having been peneplanated.

In Taku Arm belt, the striking uniformity in elevation of the mountains of the Coast range suggests that this terrane may be an uplifted and dissected plain of erosion. Moreover, the upland surface of the Yukon plateau merges with the summits of the Coast range in a manner suggesting the synchronous planation and subsequent uplift of the two provinces (Plate XID). When the Yukon Plateau region was uplifted, the adjoining Coast range must also have been forced upward unless faulting occurred between the two terranes and there is no evidence of this; nowhere, for instance, are valleys known to exist along the junction between the mountain and plateau regions, which might indicate faulting. It thus seems prav- tically certain tt these provinces suffered erosion during the same

‘ Brooks, A. H., “Geography and geology of Alaska,”” Prof. Paper, No. 45, U.S. Geol, Surv., 1906, p. 294.

Dawson, G, M., Trans, Roy. Soc. of Can., Vol. VIII, See. 4, 1890, pp. 15-24,

! peu i ' thie ipl best three serve thier ae j TT bse ite thie t t rh ! te tite ‘ belt Phi nid of the vit t 1 4 thi the platen

Pleistocene t ‘ riviilat both ‘ree cleger thitte there 4

ae

Atlin District, B.C. 25

innumerable rills to Heighbouring depressions, These effects of th work of quiescent néve, called nivation', have resulted in grading, ty a Considerable extent. the already gently rolling surface of the plateau region, and aecount te a considerable extent for the great amount of fine material that fills all the Minor depressions in the uplan surface, The presence of the snow also helped to preserve the smooth outlines of the topography, by protecting the surfaces from streain uetion,

Thus the following causes appear to mainly aeeount for the contrasting topographies of the Const range and Yukon plateau In the first place, the Coast Tunge was uplifted more than the pla- teau tract and was consequently subjected to a greater degree to erosive agencies: and as the Mountains of the Coast range fire composed mainly of homogeneous — grano diorite the forms produced by erosion are noticeably extremely irregular since no bedding planes or dines of hard and soft layers exist. to be emphasized by degradation. Seeondly, the rocks of the Coast range are generally harder and more resistant to ordinary sub-aerial agencies than are the rocks to the east, and the more nearly the rocks of the plateau approach those of the mountains in physical properties th less apparent, and more gradual is the change from plateau to mountain provinces, Thirdly, the Coast range is sutliciently high to still hid great amounts of glacial ice which is actively employed accentuating the features of the mi tains and giving them a typical fretted appearance, the case of the Yukon plateau, on the other hand, the ice, except for small masses in occasional cirques, has long since vanished from the region, and instead of the features there continuing to become more pronounced, they are being raunded and smoothed over by nivation. Thus once a difference of elevation between these two provinces was established, their features became continually more and more contrasted. This appears to account mainly for the striking difference in the physiography of the two terranes, although apparently synchronously planated and uplifted.

' Nivation in its different phases, relations, results, ete. is discussed in the two following articles —

Matthes, F. EB. “Glacial s¢ ulpture of the Bighorn Mountains, Wyo.," U.S. Geol, Surv., 2ist Ann, Rep., Pt. TT, 1899. pp. 173-190,

Hobbs, W, M., “Cycle of mountain glaciation,” Geog. Jour., Feb., 1910, pp. 147-163,

26 Gec Logical Survey, Canada

The Valleys.—-The main valleys in Taku Arm belt are character- istically wide, steep-sided, flat-tloored, U-shaped depressions with decided topographic wunconfermities everywhere in evidence at the contact of the upper edge of their walls with the upland surface (Plates V and X). The master valley of the district is that occupied by Taku arm, which is about 59 miles long (Plate XV). The lower (northern) 54 miles of this water has an almost due northerly trend, but above there the arm turns abruptly to the west at right angles to its previous course. The upper 45 miles of the arm lie within British Columbia and occupy a median position in Taku Arm belt. The water itself is in most places from 14 to 2 miles wide, but the entire valley bottom has in places width of as much as 4 miles.

The depression occupied by Edgar and Nelson lakes and Hale creek is really the southward extension of Taku Arm valley, but has been so filled with glacial debris at the point where it joins the southeast corner of the arm that this water has been excluded.

A number of important tributary valleys having easterly or westerly trends, join the valley of Taku arm. The more important of these are occupied by Tutshi lake and river, Racine lake and creek (Plate V), Fantail lake and river, Talaha bay, Graham inlet, and the extreme upper end of Taku arm and the glacial creek emptying into it. These are all steep-walled, U-shaped depressions and much resemble Taku Arm valley, differing from it mainly only in being narrower. Those of the tributary depressions that contain lakes drained by streams into Taku arm have had large amounts of glacial materials deposited in them, which have dammed back the waters above, forming lakes. In addition to these large valleys, a number of smaller streams, occupying less prominent depressions, have hanging-valleys.

The U-shaped steep-walled character of all the main valleys, and the reversed slopes of many, causing lakes to form in them, are due, mainly at least, to glacial action. The upwarp of the dis- trict, previously discussed, gave the streams renewed life and energy, and they immediately began vigorously sinking their channels in the uplifted surface. Throughout the area deep V-shaped incisions were rapidly made, and these, in Pleistocene time, were invaded by

racter- at the urface cupied lower trend, gles to within . Arm has 4

y, but ns the d. rly or ortant e and inlet, creek ssions mainly s that large mimed larger ninent

alleys, them, 1e dis- nergy, els in ‘isions

led by

Plate XIV

28627 —p. 26

The wide U shaped valleys are here weil lustrated.

Looking easterly across Taku arm, Graham inlet, and Atlin lake.

Aah way NP] fo saPpeTEYD Bur .eyy af

84) Buimous

Auepunog BiqQuinjog ysizt

49 Puke UvOYN, Oy) UKeU wOsj Wue Nyey dn Buryoo7

“AX Pig

Atlin District, B.C, 27

glaciers from the mountains to the south, southwest, and west, which have profoundly effected the topography of the district,

When a broad ice-sheet covers a district, it moderates the tope graphic features and reduces the relief, by eroding material from the higher elevations and depositing it in the depressions, but where the ice occupies only the valleys, as was the case over the greater part of Taku Arm belt, much greater results are seen and of a different kind; the interstream areas maintain their even character unaffected by ice, while the valleys are widened and deepened, th maximum effect being produced in areas which have been previously prepared to receive the ice by having deep valleys alr uly made in which the ice can operate. Taku Arm belt is believed to have been so prepared, and in it V-shaped valleys have been transformed into wide, deep, U-shaped depressions, and hanging valleys, cirques, roches moutonnées, and other well-known glacial forms have heen produced,

The main valley glacier in the district moved northward through Taku Arm valley and was joined by smaller bodies from the tributary valleys from the south and west. A considerable tongue of ive moved easterly dewn the valley occupied by the exireme upper end of Taku arm, and a similar body moved in a parallel direction dows the valley of Fantail lake and river, and was in turn Joined by ice moving northward down the valley of Bighorn creek. Other valley glaciers moved westward down the valleys of Racine lake and creek, and Tutshi lake and creek, The main ice mass in Taku Arm valley divided at Golden Gate (Plate XVI), and a portion moved eastward along the valley of Graham inlet and joined the greater glacier in the valley of Atlin lake. The ice thus all had a general trend north- ward as the water has to-day, but, similarly, many tributary jce- streams moved in various directions to join the master-valleys,

In addition to being mainly destructive, the glaciers also acted in a constructive capacity, and contributed vast amounts of morainal and other materials which in places deeply covered the floors of the master-depressions (Plate XVII). The waters of Taku arm ani! Tagish lake are impounded by glacial materials deposited in the valley of Tagish lake, and all the small lakes in the district occupy reversed slopes produced partly, at least, by glacial debris deposited in

on CPROLOGICAL SURVEY, CANADA

the lower portions of their valleys, Tt may, however, be possible that the ice ploughed deeper into the underlying bed-rock along certain portions of some channels than along others and so caused reversed slopes, but no proof of this has been obtained and the Pleistocete deposits are always in evidenee at the foot of each lake. The pos tions now oeaupied by these bodies of water apparently represent those of the laat tongues of the retreating ice which finally melted rapidly that the depressions did not have time te become tilled

with glacial products.

Hanging Relations of Tributary Valleys.—-The small streams that traverse portions of the plateau surfaee flow over the upland in wide, flaring, depressions, with comparatively gentle gradienta, bur at the edge of the elevated platform, they plunge suddenly, by successive falls, through gorge-like incisions, to join the master streama below. In other words, the tributaries have hanging valleys, and the smaller the stream the more its valley is hanging above the master depression.

Many of the smaller streams have only well nicked the walls of the master valleys, and several on Lanning mountain, Stovel moun- tain (Plate IX), Hale mountain, and other places, fall preeipit ously more than 2,000 feet to join the larger streams below, One particularly striking example of such a valley occurs on the west face of the hilf just south of Golden Gate and facing Hale mountain (Plate XXV). The larger valleys such as that of Lanning ereek, have been occupied by considerably larger ice and water streams, and the hanging relationship is less pronounced, Bighorn ereek is one of the largest creeks in the district (Plate XXX) and at its junetion with Fantail river, almost no hanging relationship is noticeable. All gradations between these different conditions are to be found.

Various explanations have been edvanced to account for etream- having hanging valleys, and although a number of causes such as certain structural features, meander cut-off, ete., may account for this phenomenon in individual localities or cases, still when it is general thre ighout a district the hanging relationship has heen discovered to be always in some way due to glaciation. In thi connexion, it has been suggested thet since tributary valleys are

more or less contined and higher that larger depressions, the ic

ble that eertain reversed patietie 1 posi present moltert ie filled

ins that land in ita, bur nly, by Hhastet valleys,

ove the

valls of

precrpit P One he west

ura teeits 4 ereek,

ma, and

tm crite

net ion

le ATL E

etreatis such as unt for ‘mh it ts

is heen

ee]

Plate “KWt

‘cated by the arrow

unconform ities everya

toward Gokden Gate ind

%. and the topographic

Looking southwesterly

28627—<p, 28,

The wew alse shows the wide flarin U smapes onar 9 U € acter of we ma mere encountered at the upper edge of The sey ealls

valley

ATTN tematic BR. at)

® romain longer in thor atl protect them from water ¢ Potion and weathering ageneios, while the Parent etream lowered i¢s chaans Possible ae this tplanati ti tha nent ee tt ia ft acount for the

hanging vallevs thease sh thet lie fimeree Promeunceed aad pientiful on

slejee foeing the north than om those fa iti the acreet) hie does

het appear to cold true in Taku Arm belt alth igh if ia claimed t do 1 in certain other loealities.! In this diatriet the hanging felatiotehip apiwars te le due part

at least, to the glaciers in the Master Valleys favitia erect ayel

steeper theie contain tls to the extent that the lower por tions of tie tributary af ‘the Were entirely planed away, Sines the disappearance of th ee, the tributary streame, on coming to the erlges of the parent valleys, fall precipitously over their abrupe wlaeially -ateeperres Ie ts join the lakes or latwer streams below The larger the how tributary valley, the more teariy will ior ated water or i epe pauew with that in the parent depres sion, amb eur i the iailer vall is left hanging; and where tw, thierie he heating relation

ship resulting: from

Cirques {irques ao i t ! promitiont ul character istie features of the Coast ba rt the distriet, but only a few were noted in the Yukon Plateau portion, and most ef these oeeur wfound the summits of high individual mountains. Op Lasuniny

and Fetterly mountains and elsewhere, well preserved cirques oe

noted, but these generally contain little or no glacial ies; in eaeh as a rule holds a small lake which is generally in the pre being ree aimed, by ordinary erosive agencies (Plate Nearer the Coast range, however, the cirques contain more ir cirque on Coeaner mauntain is partly filled with it durin entire Year

Ss the Coast Range mountains are approached, Cirqiesa becenn: tore numerous and glacial ice more and more plentiful, until the ereat Llewellyn glacier is encountered, which overrides all but the ftier peaks and spurs, The cirques oecur around the rugged sum

mits and along the ides of the various idges, and excavation eon-

‘Garwood, E. J.. " Features of alpine scenery due to glacial protec- tion,” Geog, Jour., Sept.. 1910. p. 317

26627 —§

30 Geological Survey, Canada

tinues backward and downward wantil the cirque-walls from opposite sides of ridges aud crests meet. Knife-like arréts and needle aum- mits are thus produced, and the topography assumes the typically fraved or fretted aspect so characteristic of the Coast range (Plate XIX).

Facetted Forms.—The great masses of ice in the master depres- sions planated the valley slopes, reducing all projecting spurs, ridges, ete., and bringing them into alignment to form in many cases quite regular walls, Since the close of the glacial epoch, the numerous small tributary streams from the upland have been cutting channels in these walls and have been enlarging the pre-glacial incisions in them. The result is that numerous V-shaped trenches are cut in the steeply-inelined valley slopes, and between them are left facetted forms, carved on the valley walls (Plate xm):

These features are quite pronounced along the head of Taku arm (Plate XXT) and are of common occurrence in the upper por- tions of the various transverse valleys leading from the west (oward Taku arm.

Terraces.—Terraces are of somewhat rare occurrence in Taku Arm belt, but a number were noted on the west side of ‘Taku arm in the vicinity of the mouth of Tutshi river. They range in elevation from 10 to 250 feet above the arm and are composed dominantly of fine well-rounded materials. Similar terraces are of common oceur- rence in most of the main valleys throughout the Yukon Plateau physiographie provinee, and have been deseribed by a number of writers.)

The origin of these terraces is somewhat in doubt. Dawson and Spurr considered that subsequent to the uplift of the Yukon plateau, and after the valleys had bee me deep!y trenched, a submergence vceurred in late Pliocene or Pleistocene time. The valleys are thus

thought to have become partly filled with gravels, sands, silts. ete.

‘Dawson, G.M,, Trans. Roy. Soc., Can., Vol. VIII, Sec. 4, 1890, pp. 36-41, 48, 49, McConnell, 1. G.. Ann. Rep, Geol, Surv., Can., Vol. IV, 1888-89, pp. 47D-28D. ? Russell, T. C., Bull. Geol, Soe, of Amer., Vol, I, p. 139. Sparr, J. £., Geology of the Yukon Gold district ’; Eighteenth Ann. Rep., U.S. Geol. Surv., Pt. TIT, 1890-97, pp. 268, 269. Nordenskiold, Otto. The Amer. Geol., Vol. XXIIT, pp. 291-292. Brooks, A. H., Prof. Paper, No. 45, U.S. Geol. Surv., 1906, p. 296.

opposite

le sum- ; ypically : 5 (Plate 3 depres- ridges,

ps quite

uced the cirque has long since disappeared

merous dannels ‘ ions in é in the Fy acetted g Zo ee SE r Taka $3 ©é wer por - € oward 2 a3

gion

1 Taku arn in vation ntly of oceur- *Jateau

ber of

and erosive agencies are now active

on and lateau, Trence ‘e thus Its, ete.

), pp.

‘Cypical cirque on Fetterly mountains, in the Yukon Plateau re

ISSSK-89, 28627—p. 30,

h Ann.

4 4© pus 40ddr ay) JO Yynos ysr w0sj @bUB SPOD BY) yO mars sBON

as JO WORE: yeroes6 03 any

) Gaajs 943 smoys main o 7 wae Ny¥ey JO pua seddn auy

ss0.08 fHuryooq

se sens een eessoeenen-enietenenen

XX Sg

“xy ?%g

a6 Bul ye

use Oy) BAOgGE Spey

3d asd By, SMOYs Man Oyy

Poe6 ay) pur ‘siyem tise OME] JO PROY QuWaZ} Ke ay) sx

© Asaysamyysou Hur xo07

ATIIN bisithior, Bw, bl

After a brief period, elevation eemmeneetl and at the atreama it down through the debris, terraces were left linging to the valley valls, the amounts of the subsidence and uplift being indicated by the terraces

The postulation of a submergence and sul vequent uplift appears to the writer to be quite uncalled for t explain the origin of these terraces, It is true that a eertain amount of uplift haa oeeurred in recent times and may be still in progress as indicated by es rtain reck terraces along Yukon river above Dawaon and elsewhere. but these appear to have had an origin quite distinet from th: wrave sand, and silt terraces which eharacterize many of the valles of northern British Columbia and Yukon. ly whatever manner the terraces were formed, they must have originated ainee the wlacial period, otherwise the valley glaciers would have entirely obliterated them, It is further evident that no great amounts of material have heen deposited in the vallewa eines glacial time, as in many d ‘pres eions, such as along the White Pass and Yukon railway between Careross and Whitehorse, around Annie lake’, and in places alony Taku arm (Plate XVID), the valle floor is pot-holed and minuteds rough, and possesses etill the characteristic appearance of a surface

that has reeently heen overlain by jee

Brooks und others have supposed the terraces to be due to changes in the erosive powers of the streams, and in places this appears to be true, but in Atlin district and other portions of Yuko territory where the terraces reach high pon the valley walls. th theory calls for the former existence of vast amounts of mat rial ever the present valley floors, which, as shown above, cannot be the case, in some localities, at least.

It has been also Sup yy sed that the terres are really remnants of lateral moraines formed along the edges of the valley glaciers und that they consist thus partly of ground-up debris accumulated by the iee itself, and partly of materials that rolled down the sidehills fromm

ubove, and gathered along the upper surface of the ice, As the ice

!

retreated and stood at sueceessively Je wer ele itiens, other aeeynu

lations would tend to form, and those left. above would remuin

Cairnes, D.D.. “ Wheaton district,” Geol. Suprs Branch, Dept. of Mines, Can, (Memecp No. 31. 1912

ue GEOLOGICAL SURVEY, CANADA

; the form of terta ine! ! valley walle The thost per sistent and prominent of rt would this mark elevations at hich the jee maintained stunt elevations for exceptional lomg periods

Its certain valleys where the terraces have been poorly pi

served it is diffieult to disprove thia theors lov over, at points Wheaton district and elsew jiiit eXtensive flat Ct terrace 4 ilatietis remain in e mottla of the tributaries, and esxtetid out flash with the edges of the walle of the master valleys lt thi terraces Mithatoat due tou ice action, the ice would alan have inverted tl mouthe of th ty thafles if the entire lower prove tieetin

of aueh would not now contain Hat-toppel accumulations,"

It this aeotia oy it. vated by Nordetekjold andl other, that these terreces are ni ita t least, lake terfaces and repre cent auecoss elevations at wi 1 the water stood in post wtlacial tithe 1 his calle for a damming f th dr Vi SVetOE scree whe rr along the lower Yukon river. As the terraces indicate that the period of submergence was brier, the a ning wee probably cee

to accutmulations of jee or other glacial mareriale

Dehain Age

All the waters of Taku Arm belt drain into Taku arm and are thence conveys throwush ‘Pasish ike, Maral ev, bew riser, ated Yukon river, to the Aretic oeean corn tipios a median prosibieny ttt the diatpiet, is i tiheasl pl i from thet , banilers Wide, aed tiie a lenge f about 30 miles of wh thee Ggeer BO enile The i h Coluatl With the exeeption of the or “ hh tren eustertl t hii OLN alist bidee there thie

(iraham inlet, ch is 16 miles long and about a o wid Faku arm fr he cust, at Golden Gate Phe titers of At

Irainm throw Athin river ane Geral: niet t i

The prineiy wlics of water in tl t re keigar Fantail, Racine, and Tu hiake I to ! by rapid streams flowing through channel ortit in glacial and post-glacial ris The more important <tr ire these draining the Taal hieh Fag river is the :f nh addition, B

Cairt ss Ue i) eyt Ser ection on terra “

ATEIN Etim datey "4

hoen reek, tril fury ef PF aatail ri f ‘

atreaim A lore, wlacial ere ke, alee, Hiplies info the extrerny iter mat per

ent of Takw arm atid thows theretearh Wivle flats

treed of hone at which ope till being rapidly produced by the Miaeior i hom and along the sides af the valley (Plate X NI) Phe other trean the distriet are of mince iy aa Nil the streams op thy ly pn to fapid floods, as js evirletieed by the prownee of Wihe grave! at itite 1)

vend tate and bare in the mor topertant drainage voller.

Es tengopne

es, and valleys CLIMATH © have wen el Hie elimate of Atlin distriot and adjoining portions of morther - British Columbia and southern VYukor bes been, and by many ati ; is, thoughe to be much more sever that it really is, Pt is true thar , mi ce , furing the earls Fueh inte Atlin in Petes tied PSH) preat hapdel) en a wi re codured in sor cases, uted lives even we re lost, but whom it “0 an es rethetiberod t] The tmajority of the wed wukers Vere aeru rent ‘ fod ee ne he ert om ote Fewion hor to encounter the ordinary Tree t ms oof tpiaes teorthvotn Latittichess : that tany of the por ‘ p r tout on re pttesst with cobs the Vaitiest netion of th Posie be traversed. that ¢he route chosen was often eoreer cot thye tinder th Histine ss; gid that a here pr portion aft ‘ j hors trade th rp daring unfavourabls Puss it Pay ate! ber rperis that tsualties oeeurred, rather than a. Law ‘see icicles inee this te Pass and Yukon railway was mmatrocte aver Hits ¢ Pa t. and teuiliet sere place Loon the HaV bagi eit tee erron ress thet y the e imate of Atlin ha lernel I To octied thre beeing wemerully better wld ; Urn ul irt rly delightful, 4 hi y oNe A i t i sfitticl ther H i Petty Ful ml for for mpi rt ! heta Njur wl Phe Tad) nt t ' ni ith res l i riding te their

; cae evation i rex ‘ t I rl tow? hi ei : Js mt well noth Plat i that ;

MICROCOPY RESOLUTION TEST CHART (ANSI and ISO TEST CHART No. 2)

Ffefeeee Eeer

fre r fr

APPLIED IMAGE inc

1653 East Main Street

Rochester, New York 9300 - Phone

14609 Sa

(716) 482 (716) 288 - 5989 - Fox

Ot tj ROLOGLIOAL SURVEY, CANADA

is inelined to be dry, although searcely sutheiently so te be termed mebbil arid,

Vegetation in the lowlands is luxuriant and its growth extremely rapul ‘The growing season seems short in number of days, but this is counterbalanced by the length of time the sun remains above the horizon, and the consequent increase in the number of hours of insolation. Wild fruits of several kinds cecur plentifully and grow to large size, Agriculture bas nowhere been ser ously attempted, but gardens containing most ef the common varieties of vegetables were seen in ceveral places and all wore doing: very well and com pared favourably with those seen in southern Byitish Columbia.

Tne rivers and creeks generally open early in May, but) on some of the lakes, ice remains until the tirst week in Pune, Slack water stretches freeze over any time after the middle of October, but some years the rivers and Jakes remain open until December.

Surface placer-mining operations may generally be commenced early in May and continued until about the first ot November, and all outside and surface work in connexion with mining and similar industries may be conducted for six mouths im th year; and on account of the long days, work may be performed during a con- siderable portion of the summer by night as well as by day, without

the aid of artiticial light.

Fauna And Flora,

The valleys are generally well forested, but trees of any con- siderable size ure not commonly found more than 500 feet above the valley bottoms; however, in some places the forests extend to 1.500 fect, and quite large trees were found in some sheitered spots, as much as 2,000 feet above this level (Plates XXUH, NXIID. The main varieties of trees that occur are white spruce (Picea alba), black spruce (Picea nigra), balsam tir (Abies subalpina), black pine (Pinus Murrayana), aspen poplar (Populus tremuloides), balsam poplar (Populus balsamifera), willows (Salix), dwarf birch (Betula glandulosa), and a species of alder. Of these the white and black pruce, which occur in about equal numbers, are the most abundant and valuable, and furnish strong, easily worked, timber well suite]

for the usual mining needs and for purposes of construction gener-

tertied

‘tremely but this rove the ours of id grow cipted, wetables

nd Com

nbia. but on Slack

October, ember.

nmenced ber, and similar and on roa con

without

any Con- et above xtend to ed spots, Ey. ‘Fhe va alba), lack pine

balsam (Betula nd black abundant ell suited

ym gener-

Piste XX.

The timber is also seen reach Mg in places wel: up on the valley slopes.

Showing a typical, wide somewhat heavily timbered depression

ee

28627—p, 34,

Looking across the valley of Fantail river and along the eastern face of Hale mount

ain his is one of the most thickly timbered portions of the Taku Arm belt

Fite te tt ‘ ' i ‘ te k 1h epee rrien feet ft feet ine cbeeente te He tt ' j Per HHP Cee ePED ER per pel tte 1 thy tfrer trees tips Vater bhaek pis Is thet eet j' th r pe ted Paredy enNeeeds Pe pied rom t Mrounels tf bs ceeustonally foci! tite wr t thre i OFmitw sepurate groves, but the Pu rows ot tichy bee i the thitin strean Phe balsam tir. whieh Wy t 1 Tithber, thrives best cu the sterpaes bree fptpebeeg t ere on I Sore observed having fv t Ps ined Ciitenpes ! plies moet fat bordering ‘Taku arm, the best of the titebepr heen cut ‘ cob trates Lupeaber Nesp popiiee ated barbeane pn re ' have pucrt forest growth beth in three vaytley roth tileieds have over TO itpely strimipes, aeted thy Of valite tails ws fuel, Willows, dwarf bireh ane alder ocetrer pleartifuly nt tte Hel oon the bop and the clward DIPCH, tte places, extends te the Plateatelewel, aod with the willows whe alder, int phi hetitut dense ua grow de that vilhinw tate very dithend Several Virieties of wild fruit. Were preted fo owhieh oy Woof Heather berries (Binpetrum Megr tHe), ate the most pleutit til ire Tortied ahundantiv in mest places to above tinaber-Titne Ns the trries are very juiey and palatable, thes are tauch prized by miei tain climbers in these horthern distriets. Lew h sli erunhery (Vaccinium o weaoecus), NWigh-bush eranberries (Pity, pres Hori), ved currants (Riles rubrum), black currants (Aibes uduon fentm), gooseberries (Rises lay ustris),

unvifotiny, raspberries (Rubus strigosus Fe diginosum and V

heer florida) alse occur in many parts of Moose, caribou, sheep and genat

localities,

the

The caribou is the large giant (Rangifer oshorne)ys the

Lout

is the white an HOnEAHUS) +

and the sheep are of two varie ties

Ovis dally, and the snddle-bac k o7 I fai nintt)

Black, brown, and grizzly bears wolf, wolverine. beaver, offer, marten,

iitie

strawberrios

eh SOT NN

faunin’s Mountain stv

(lh radari

blue berries (Va ceaspitosiuim), ayd Saskatoon

Cretan berries (Amelan district hat plentiful iy Hn Variety, Osborn’s enrthe

lope fout (Greamnos

Dall’s Mount tit

op t Owes

are also plentiful, The

INnN Are

somewhat

aS Sek gE

aly GhOLAMICAT, SURVEY, CANADA

moon. Ordinary red texe= ae well aa cross, black, ated silver foses re oeemsnonally tered Ptarmigan re exceedingly plentiful, of thick the pock ptartviwan (hagepus raupestrin) wot whiteetailed

Plarmisan (Lagepus leneurue) are found abewe timber line and

luring the sumitner teotuths ive tainly the highest, often anmeow Pr The willow ptermisan (Lagepus lagopus) exist during the summer months at about timber lin Bhie grouse or

Richordeon grouse (Mendragepus Richardson), fool hens or Frank lin arouse (Canachites franklin), willow grotwe or Oregon ruffed grouse (Bonasa umbellus sabintjars fairly plentiful and an occasional prairie ehieken or northern sharpetailed wrous:) (Pediaecctes phasi Cnellus) was also seen; these live mainly in the timber and preferably in the valley flats. Rabbits, which are periodieally plentiful, have heen almost extinet for the past three years, but during the past slimmer they were noticed to be amuin rapidly ineroasing in numbers

Ihe lukes are generally well supplied with fish, mainly lake troct, Whitefish, and wray ing. Grayling are aleo plentiful tio many

of othe streams

GENERAL GEOLOGY. GENERAL STATEMENT Regional.

The main physiographic provinces of rorthern British Columbia,

as previousiv vertioned, are coextensive with those of Yukon and

Alaska to and follow in a general way the trend of the Pacitie C iw. 2). As topegraphie features are often, te a certain xpressions of the bed-roek structure and con position, it e expected, that in all probability, the s general

geologiea! horizons whieh compose the cordillera in’ Alaska and Yukon might extend southerly and southeasterly thracgh the northern portions, at least, of British Columbia, and to a) limited extent this has been found to be true

Dr. G. M. Dawson' has shown that there is a certain continuit' mad litholowieal uniformity along the strike of some of the geologie

terranes in British Columbia, In addition, a geological map of

Dawson, G.M.,. “ Geological record of the Rocky Meuntain region, Canada,” Bull. Geol, Soc. Amer., Vol. 12, p. 60.

ferMere ful, of ro tatlet ne and + anow

ouee of Frank

ruffed ‘neional pliasi

eferably tl, have he past umbers ily lake

tho rebar

slumbia, kon ane dot the ften, te mid eam general “ka ane uh othe

limuted

yitinuit geologye

map of

n region,

STLEIN ‘BT RICT. By oe

Weetert: © ated) eotmpibee harwedy tec the otk f Da werrny fl

MeContie ule shews thot the Hhistribution of the tore important

wechomie features exhibits in oa browd way, a tiathed parallelism, and

rees rotuchly with the tain physiographic divisions Brooks has

in Alaska, althougl

ir rthier sbierwvee that thie tes ssc tlegpree: breatche te tet fer the sine extent ox further ter the tthevat, anal that cope

of the larwer ge logic terranes extend thers Yukou, and Alaska, fn northern Heit

ith British Columbia

Columbia this paralelicn

Hel fo some extent conformity of teclogie formations te the steike

ef the plivsiograph Prov ites are WIS apparent when a bese

triet is Cotmnered, and ape most evident wher the entire norther

pertion of the Province is viewed

Phe Coast range consists of an inecus complex of granitic

rocks, largely granediorites, intruded mainly as a great bathelitl

tore than baa mith in length, that reaehes from south of the dork

to reuply TOO) rites orth of the Hoth paraclel (the British Colunibin

and Yor beotrrelary) Phis bathotith extends alone the th

ester and Western portion of Taku Api belt and te the one peadls

Prominent geologie feature thar tute any morked trend puratlel te

the coust Lins and the main physiographic features of northern Brit Columbia and southern Yukon. In fuet the

h main ber of these

KPanitie poeks coincides practic ily with the Coast Runge topographic

Province, aithough in places these intpusives extend out inte the y kon plateau The fortnations composing the Yukou Plateau provines in

northern British Columbia and southern Yukon, in few places

show any tendeney to parallelism with the topographic terranes. bast

instead are generally very irresularly distributed throughout the

district. Only a small portion of this tract has been mapped or at

all closely studied. so that the geologies!] information eon riiitie it

is very incomplete, Still, the general distribution of some of thy

larger subdivisions of the gee logical column has been ascertained

and the formations are known te range in age from lower or older to Recent.

The Most anerent rocks Colsist of a se ries of pre-Dk Votan

schists, gneisses, and lime stones, which have suffered intense dyna-

Geological map of the Dominion of Canada, Western sheet, No TS3, (ieo!, Surv., Canada

ry 1 Peper . § heoth af tf ‘ t ti F hiiertly rely f lower ting bute trier benerttabeert bty Peet a rie t ritvite teh i fates reuse that r ‘ i i ‘ Riictige batheotitt t; i t i 1 bisene r pierPer peeconet thieare the t pitt pane ene t ’ i et tl thee Hh, atid i i i pate ith ‘ t ire cet ferent thet i re, bet eevee t Phe aedimentory roeks, with the exeeptian of thewe ttretttebed 14 th vehasstiiod metamertplin pou Ti lewd ltete theres sole thiewee t Pilwovor thers et Meaezene ane thieves (Jiaternars age Phe igtienus poet ripeiee both pateristye tel ent is Hepabet yeh Petteae ! gre Pertie ctpprerspiinatieeds bee Piheosoie to Recent The Pulwovote sediment i tof wv series, several theataaned feet theky ceeenepy od meatal Pdeevertace Cocaphwotnttererte bitters tenes ates, ane artvites, and possibly also imelude the chert the mentioned Phe lower meni f are elites qpuartziters anid fate with their u crated chert mel sve Tittte stone bates, whereas 1 tipepret breed iP prinengaedls Hieay b Saeedelerd Pepppersterte The linn

totes capped ter te mueh more extensive than the lower members and eoretitute cnaportaret teriace ith tee pens taanne’s Wins north westerly trend parallel te that ef the Coast range the west, One

auch range beoreler Dawes river, ohiethy alors thy eusterny miter,

from its headwaters for a ebbsturies f ever LOO) miles Phe Mesozerte eubioent op if confortable seriea of con glotnerates, sandstones, wrey wie! hales, tuffls, and breeeias, of Jiura-Cretvecotie age whieh eovor extensive tracts, tect 14 th places an ageregiate thickness of ax titel: aa 6,000) feet To j

north, the bends gradually the Pesse! th extent wd relative in ae

e

tanee, while the associated volennies deerease

Phe Q)iaternars depe sits eonsiat of Pleistocene and Reeent

materials which are lithologieally early identieat, ned, in sotme instanees grade into cach other ; most places geological studies

hive not proceeded far enough te alow of their differentiation Vhe

Yoistovrene aecumubttions consist of uneon tlidated @ravels. sands

are tute tee i tettite ' ! i - tee t r ' j 7 Thre U ' he Const Ht wt ' tl or Pi thed tt t j ! ' pit xt theres ‘ t ( i ite i t stil rite the rt hee ere t Raat teathyotee F tte ia i ‘ Thies pebittecadt r t t t wa) L tee beeeve Preverty ite fewt Pp % uUreut+ t eri t, tm dacs titi steel evotistiturte: thee dost pareneteendt tt tes ' fentiipe ih terthweetern British Cotumbia ame ithe il ern Vukeot ate Newer thin the alter mienibers of the €oast Range HitPites Has U Hhe-spreited series of aide ‘tes and andesitie tulfs cdl breeeiias, lim etn Vhrcet ee: emp terrepres tea tientpe f bl settee newer thate the ee Purat'retaeeois sediments. Yoore peerent ! itiedemitie meee horth rt ertain ite Tortior wy Plopetocen rrin trite One the formu exterirve: thaw Odrys ty thy evel: nonmt forms th Wo midde, valls of Miles canvon near Whitehorse nyine these, in plac re eX tetpses eevee teat berth salt Py he wn Po eens HHL steve} ite ured swenites purr i bth Med nat a 8 about this time, bur it is ot kaowe ol r after tl waite Th usult Phe most recently conseliduted ro , i rhyolit richst sul haetites HE POF poured over the eountey jo place. ; t ; nh thieknema: they were beer prttpbeed eut ! 1 Recent hrecoins sare atindies

‘In southern Yukon a faver in places as much

sana ‘no aren estimated to he of, at feast, 25.000 spare Mii fes

10 Ppolaotcat Survey, Canada

Local

Repre eerstative f the bifferene 9 j ' that t hee tea Pileel a tering ttt the Conet Range amd Yukow Piates portiotia of northern Hritiel Columbia and eouthern Yo von,

ip in Taku Agm belt, a that on aeeount of the dis reity of age

eharweters f the war is fortation= comprising these greet the geol gy of this ara tilPieate Phies peeks inee tied fee Edeew eres bats ateepehitbeliters, mwedebete, weterians tel Litttes tities tian ¢ 7) sheet intl alates, well as stiches ite eteeepiter, ebbatea btied thiegttie site Carhetpiferette Etre tore Dterieate Pititie bever ‘ Pura Peta eerie eotighotietites, sancdatenes shales, gpevwackes ital tuffe; Pertiars sth) Pleistewene € 7) aticlesi tticlesitice tuff wratiite porphyry, basalt, baeale tuff tfhvelites, aml rhyelitic tuff. nt QQhuoternar if wPuvels ite, till peat wrestitieb-iee, trethele, ete The olsbest tex Whe Wee fee enrertep top the eblbetpiet r tevettelerd tue

the Mt. Stevens group whieh cotsiat= chietly of schistose amphibolites,

Hitshed boosie velewiies, mien: and hernblendewneleses, serleithe Hebets, epenartyitese peel Titeeeetertes Phese ceeur mand tee thee southwestern part of the aroa, in the form of a more or bes een

nected belt generally from 7 to 10 miles wide, that extends alonug the enuetern edge of the Coast 4 ite Phe amphibolites are prevailingl eth

fissile to slightly schistose, The mashed voleanies present the

nels textured, greenish rocks that vary in structure from deci

ippearanece of laminated atidesites, are dark green in colour, geteralls fine-grained, and although quite schistose, in most places, break inte irregular fragments The gneisses ore, in the main, grevish te greenish, medium te coarsely textured rocks of decidedly gnets teh hal it Whieh tniea and hornblende are generally conspieuass componentis Phe serieiti schists are light eok rredd, generally eofe ard frinb'e, flnedy textured rocks possessing fiesility ina high dewre The quartzite in the few plices in Which they were encountered, ape hard, fine-pr red only slinhtels woh peters rocks runging in colour

from nearly white to pale greenish. The limestones secur in bod

‘What follows under this heading contains in condensed form all the main facts of the general geology of Taku Arm belt, and is written partienlarly for those readers who do not wish to follew the details of the geology, but rather wish to obtain in a few pages the main points concerning the subject, and so be in a position to turn at ones to the chapter on economie geology,

A LIN bimittite yr, Bw il

' Etimts bP Ff t th os 5 tiul af ifimatel $ stat ; — : lat ' : ayes a 3 spre - E teeth ef stall ti th-orvetallitne Nil theres Ve my ene metborm an " om, Biceehy poliewte Hel eretitopteed. atic hiwt Heotannecepl i thet ds age thimtiy prelees the ortwinal characters of the pucks have heen entin if theatre 1, ated it tipeoemitvle try be even © al Page POSS iy hentar Prge ete sits fi eur P bitte Ebtie @ gest peettion of Yukon ap we Piritiah Cod Heluching the @reater part at least of Taku Arum ps cee belt se bvecdeord by the sen ared re ined imuredateet until. at f tulle; Well tities © arteomifere a the steel ral thertesated feet of Dh pyaar Carbontforous armitlaes A ituel culewrecis —s Ts ‘ Were cepesited, ated thaw eometitute the salutes and possi] : : , eherts of the Taku Kroup, and the Heraebirn too hee oa itt Phe thembers of the Taku Kroup oterop ss the . tibotites, aPoue. ated cometet muatnly of lepts erie slates eherts pat pigs colour from light and dark gre ¥ to black, grey and black Varieties wu predominating, but in places on weathered surfaces they are pecddi ser oWity fo the oxidation of stall ame tite cf ccemtiim ad ppetpect thy ee the #fe alee hand ated beritth: and break inte sharpeodwed, jrrewulart we a shaped, fragments, An ana'ysis of a te pieal specimen of theee ehes si on (See under Taku group) indicates that they are highly mn ene : iD tioep lg od theese ms ocldtments The fesoeinted slates eter eneralls possess a wellcleveloped slaty tru: ure, cleave readily into th ate plites, and are dark, or nearly black “4 eolour Jeu te Phe Braeburn lheppemtestien iteropy extensively iy Pb: Aves, by sttiets

and compose the hills on both sides of Paku arm for vo

Mite Preetts precio a

Pavish lake They are at least [twee feee thiek,

J VFS FE at ribet pe lly weft

Trem setiterv=talline to crveatalline ane range in colour fred eure

ith blie to atmost white red, are

The time interval between the ¢ trboniferous and the

‘ eolour ;

of the Jora-'r theeotis deposition be tet represented by ans tj

in bed :

ments, and probably during this interval Atlin cistejet Wie a part

orm all of a land area subjected te efosion and intermittent welecas written

Hh Vib= berths etails of 1 points In probably post-Carboniferous, pre-JPurassic time, andesite. e to the

indesitie tuffs diahase, dic rite, at

d tiagnesion rocks, al’ of whiel

aie

$. (hObOGHONE SURVEY, CANADA

ire considercd as qiembers of the Perkins group, invaded the oldey rocks and buried them in places under considerable thiekuesses ot lavaound titaeeous toateriah Certain members of this werotip, bos ever, nay have originated as early as Dovorntan tine Phe Perkins rocks are of considerable prominence and extent, and are found on various places throughout the Yukon Plateau portion of the distri

Phe andesitie reeks are iuvariably dark-green toe aimost blaek in colour, are finely-testicred, and generally extremely hard and britth Only one small area of dinbase was found and this consists ot

ks that

median textured, dark green, distinetly holoerystalline consist mainly of basie plagioclase, uralite, and chlorite. The diorit: also was found outeropping over only one small area, and is a holo erystalline, granular, greyish to greyish ereen, tinely-textured roel in which plagioclase, hornblende, and wugite are visible to the unaided eye, The magnesian reeks consist largely of feldspar, Inawnesite, and iron, and are tinely-text red, light te dark green in colour, und have generally a schistose strueture. Portions of these rocks are much more susceptible to weathering agencies than others, s) that their exposed surfaces become very rough and are always iron stained owing to the oxidation of the contained iron-ore minerals.

A wide-spread crustal movement, possibly the greatest in’ the history of the district, occurred in Jurassie and probably late Jurassic time, and was accompanied by the injection of vast amounts of igneous material including a great part, at least, of the granitic rocks of the batholith composing the Coast range. This batholith is composed mainly of grano-diorites, considerable portions of which were, however, intruded at a later date and subsequent to the deposi- tion of the Jura-Cretaceous sediments. These Coast Range intru- sives in addition to constituting the Coast range also form numerous dykes aunt isolated, irregularly shaped areas in the plateau district to the east. They are prevailingly fresh and unaltered in ippear- ance, and are predominantly greyish in colour, although sutticient orthoclase occurs in places to give them a somewhet pinkish or reddish aspect. In places these rocks are quite porphyritie and contain feldspar phenocrysts as much as 14 to 2 inches in length.

At the close of the Jurassic disturbance a considerable area was above the sea, and what was probably a short period of erosion ensued. This was followed by a gradual sinking of the land in

Hie cobehevg esses of tipo, bierss Perkins

round ve

distriet Udiveh tn 1 britth sists oof

s that

e cliorit: sa hole red roel

to the feldspar, yreen in of these 1 others, Ws iron erals.

in the Jurassic

nts of

granitic atholith f which - deposi- Pp intru- merous district i ppear- utticient kish or tie and .

rea was erosion land in

ATLIN DISTRICL, bee I

Jura retaeeous tin ted this cemptiertterd tara \le Thatss including the grester portion at least Paki Nera beds

subinerged,

Phe materials ac

tntatod in this PiraCretaecous seas in Taku Ari belt, were ehieth sueh as have produced, upon consolidation,

conglou rutes, sandstone z, shales, cond Rrevw whkes, Whiic h have lene th

ehassed as members of the Lab hye series This serie so Conta hah and other materials apparently deposited ipon diane “Phe Tan talus conglomerate beds that overlie the Laberge roeks. adee appeae

to be largely consolidated river gravels

Phe rocks of the Lake PRE sefies outerop over jn sstlely one thie of the Taku Arm bet and consist of shales, sandste hes, Conmlomerate greywackes, tufts, slates, and quartzites, whieh have wn aggregate thickness of at least 5.000 feet Only one small exposure of Tantalus conglomerate Was found and there only the lower 30 feet of the bed- remain, the overlying portions having been removed hy erosion, Adi the important coal seams so far discovered in southern Yukou ane northern British Columbia have been too nd either in or imtnediatels under Tantalus conglomerate which js readily distinguishable from other somewhat similar rocks, since all the component pebbles con- sist of quartz, chert, or slate. The other conglomerates of the region contain various other materials such as granite, Tinestoane, and fragments of various voleanie pocks.

This Jura-Cretaceous period was a'so charaet rized by voleanic activity, as evidenced by the tufaceous materials found intercalated with the normal sediments. These voleanies all appear to be andesitic in character and to be related to the Chieftain Hill voleanie: chieh consist mitinly of andesites and andesitic tuffs and breecias whieh have extensively invaded the Jura-Cretaceous sediments and in places buried them under grest aecumulations oof lava. ashes. breecias, ete.

These Chieftain Hill voleanies in Taku Arm belt ceeur miaints in two areas, one of which extends from Taku Landing northwesterly toward the mouth of Tutshi river, and is 2 to 6 miles wide and possibly 25 miles long: the other area lies to the west of the Engineer mines and Edgar luke and is 4 to 6 miles wide and apparently about

10 miles long. Other small exposures and dykes were noted in

44 Geological Burvey, Canada

Various localities. These rocks are mainly mica-, hornblende-, an augite-andesites, and andesitie tuffs and breeeias, They vary con siderably in mineralogical con:position, and have a wide range o colour showing many shades of red, blue, green, and brown, but thes genera ly Possess a typical undesitie habit,

The Jura-Cretaceous sediments have been extensively invade: by the Coast Range intrusives which are, in the field, indistinguish able in character from the grano-diorite pebbles and boulders tha constitute, to a considerable extent, the lower conglomerate beds 0: the Laberge series, It is evident, therefore, that intrusions of grano diorite have occurred, apparently from the same magma, at differen and, in some cases, widely separated periods,

The Jura-Cretaccous period of sedimentation was terminated by a wide-spread deformation, at the close of which a considerable area including Taku Arm belt, and the greater part, at least, of northert British Couumbia and southern Yukon, was above the soa. Dera dation Lecame active, and no evidence has been obtained to show that from that time to the present, any portion of that region has beep subjected to marine conditions. The historic records in Taku Arm belt from the time of the Jura-Cretaceous disturbance until the glacial period are few and indetinite, and show mainly that the Jura-Cretaceous beds were considerably deformed and meta morphosed, that erosion continued until a nearly base-levelled surface Was produced, and that this surface has been subsequent’y uplifted and dissected. Since, however, no sediments occur that are more recent than he Jura-Cretaceous beds and older than Pleistocene, there is no evidence within Atlin district to indicate either during what period the planated surface was elevated, or whether or not there has Leen more than one erosion cycle and subsequent uplitt

After the invasion of the distriet by the Chieftain Hill voleanies and during a period believei to ineude portions of the Tertiary and also perhaps of early Pleistocene, Taku Arm belt was subjected to at least three volcanic invasions by the Carmack basalts, the Klusha intrusives, and the Wheaton River voleanies. The Car- mack basalts appear to be the oldest of these rocks, and oceur either as dykes injected into the older formations or. in places, as flows that poured over the land-surface, accompanied locally by tufaceous

accunmlations, Only two small exposures of extrusive basaltie ma-

nde-, and vary von: range of . but ther

y invaded stinguish- ders that e beds of

of grano- . different

inated by uble area, northern Degra- show that has beep aku Arm until the that the 1 hela d surface uplifted Ure bore pistocene, ry during ror not uplitt voleunie Tertiary elt was k basalts, The Car- ur either as flows ufaceous

tie ma-

Atlin District, B.C, 45

terials were noted; and these occur, respeetivery, near Wirthitd on the west shore of Taku arm, and on the southwest faces of Armstrong peak, The basaltic rocks range from tine to medium in texture. and from dark-greenish to dark-reddish in colour. Many of them are heavily impregnated with iron-ore minerals, and ino most specimens wigite, olivine, and basic plagioclase are visible te the unaidad eve

The Klusha intrusives are represented in ‘Taku Arm bele by numerous dykes of granite-porphyry, which cut the older formations and are of about the same age as the Carmack basalts, but whether younger or older is not detinite'y known. They are light grey to pinkish, coarsely crystalline rocks of granitie habit.

The Wheaton River voleanics are more roeent than the Carmack basalts and consist of rhyolites and tuffs, which cecur as dikes ani also as tlows and tufaceous accumulations. They are, typically, ulmost white to light yellow roeks, although in places they are iron stained, and decidedly red on weathered surfaces, The Wheaton River voleanics appear to be connected with the Klusha granitic intrusives and may be synchronous with them.

In upper Cretaceous time a transgression of the sea teok place slong the present Yukon basin to the north of Taku ..rm belt, aud also probably extended to other portions of Alaska and northern Yukon, Deposition continued well into the Eocene, although ‘in the Upper Yukon basin, the Eocene is represented only by fresh water beds which seem to have been laid down in isolated basins,” In Koeene or Miocene time, a gradual uplift occurred which, though of an orographie character, was accompanied by voleanie activity and by a considerable local disturbance of the Eocene beds. The exact date of this orogenic movement is somewhat in doubt. Daw- sen’ refers the uplift to the Eocene, but Brooks has produced con siderable evidence to show that the dynamie revolution occurred during late Eocene or early Miocene time. A long period of crustal stability ensned, during whieh what is now the Yukon pliteau, as well, possibly, as the Coast range and other adjoining traetst were reduced to a near'y featureless plain which was subsequently ol wated

Brooks, A, H. Prof. Paper, No. 45, U.S. Geol. Survey, 1906, p. 266.

Dawson, G, M., “Geological record in the Rocky Mountain region of Canada,” Bull. Geol. Soc, of Amer., Vol. 12, p. 79.

Op. cit., pp. 292, 293,

‘Spencer, A.C.. ‘ Pacifie Mountain system in British Columbia and Alaska,” Bull. Geol. Soc. of Amer., Vol. 14, April, 193, pp. 117-132

Th FRORAMCEOAE SERVEY, © VN ADA

Dawson! maintains that the planation was aecomplished dhurtig tf Kocene epoch, that the Mioeens Wasa period of vuleaniam, deposition tnd accumulation, and Brooks! aerees with hint in cousidering the the subsequent uplift occurred in Pliocene or carly Pleistocene tinn Spurr, however, shows that the erosion of the Yukou plateau wa vontemporancous with the deposition of the Miocene strata im the lower valley of Yukon river, und, therefore, urges that the Yukou Plateau was planated in Miocene time and Wie subsequently upliftas in late Miocene or early Pliocene time. It is not known, to wha extent Taku Arm belt was affeeted by these various movementa and disturbanees, but it. is probable that the Jura-Cretaeeous sediments were largely deformed by the Eocene or Miocene (post-Laramie) dynamic movements, thet. the district’ was peneplanated during Kocene or pre-Pliocene post-Mocene time, and that this planated tract was uplifted to practically its present position during late Miocene,

Pliocene, or early Pleistocene time

After the last great uplift of the district, the streams began rapidls trenching their valleys and Sout deep V shaped incisions resulted, and the water-ways and valley systems of to-day wer estublished, It was after these Conressions were well formed thas the Carmack basalts and Wheaton River volcanics, and probably hi

Klusha intrusives as w HW, invaded the district,

Ata later date the mountains to the west and south of Taku Arm belt’ became the gathering grounds for glaciers, and huge tongues of ice came down from them and occupied Taku Arm valley and its various tributaries. These depressions were deepened arn! widened by ice-aetion. and: vast amounts of morainal and other glacial accumulations were deposited on the floors and along the

lower portion of the walls of the valleys.

Overlying these Pleistocene deposits are the R cont aecuniila tions, composed of fluvial and littoral sands, gravels, and silts of

the present waterways, muck. and soil.

*Dawson, G. M., Trans. Rov. Soc. of Can. 1890, Vol. VIII, Sec. 4, 1s90, pp. 11-17,

Brooks, A. H., Op. cit., p, 290, 292, 293.

‘Spurr, J. E logy of the Yukon Gold district. Alaska Geol, Surv., Pt. TIT, 1898, p. 260, 262, 62

ATUUN Potmiitie 4 iH. 4 ‘7

hiring thy rABLE OF PORMATION leposition, t that Sedimentary Rocks erties i

erhies Chinas

iteuu woe \ue Portiation tithe ' harheter

ta im the

) Yul (Puoternary Surpertioncd depamits Chiefly wravels, sands, boulder clas i ukou silts, mek, peat, and seal

y uplifted

to what Tantalus conglomerate. Conglomerate chiefly with sone ear

stone and shale

lente and

soditments ira Cretacecu

: Laberge series Conglotie rates, sandstones, gre Laramie wackes, tuff, <hale late anid d during ephart sites ated tract

Miocene,

Corbonmiferotie Braeburn litesteties Doitties te one

Igneous Rocks.

lis began incisions lay wen Wheaton River voleanies Chietly rhyolites and rlyolitie: tulf

ned that

, Carmack basalts Basalts and basalt tutfs ntbly thi Pleistocene te early Cretaceous —prob ably meainty Per). reer’ rs Wlusha intrusives Chiefly granite porphyry of Taku nd huge Chieftain HE voleanics, Chietly andesite. and andesitie tuff and breecias m Valley ned aril . Puirassie (7) Coast Rane cotriusive Chietly grano-diovites ul other long the beet Probably all upper Perkins group Chietly andesites, andesitie tuft Paleozoie diahase, diorite, and magnesite

OUMEEM at

silts of , Unclassified Rocks.

1) vonian i group - Cherts and slate

I, Sec t, Pre. Devonian, pro- Mr. Stevens gy mp Chietly schistose aniphibolites, mashed

bably Ul lower basic voleanics, mica,- and horn

Palweoz blende- gneisses sericite- schists Alaska,” quartzites, and limestones, GR

48 Grological Survey, Canada Detailed Descriptions Of Formations

Mt. Stevens Group. PPS THB, EP tees

Phe roeks of the Mt. Stevens Brow oeeur onky in the south vestern part oof Toku Arm Lelt, and there adjoin aml Hie te the east of the Coast Range intrusives Which oeeupy the extreme southwest eooiuer oof the area In facet, wherever jn southern Yukon and horthern British Columbia, the eastern edge of the Coast range lias Peon esplored, these Mt. Stevens rocks oceur in the form of a more or sees connected belt bordering the granitic intrusives. In Taku \rm belt, the Mt. Stevens members ouferop throughout an ares Which south of Taku arm is about 4 mites wide, and to the north is much wider, but how much so is not known, as its Western edge lies without the surveyed belt, The area throughout whieh thes rocks o terop within the discrict is about 20 miles long in a north

Westerly direction, and from 4 te 10 miles wide PEPE heme vy PARAC TRS,

Phe Mt. Stevens group cousisis of a compex mainky of amphi bolites, mashed basie Voleanies, miea- and hornblende-gneisses, sericite-schists, quartzites, and limestones, which in most places occur so intimately associated that it would be exe edingly ditheult

te separately map the individual members,

Schistose Amphihotites.x—The schistose amphibolites are finely- textured, dark geen, reeks that have everywhere a laminated structure, but are rarely tissi'e, and frequently break aeross the structural planes almost as readily as alone them.

Under the m scope, thin sections of typical varieties are seen

to consist largely of plagioclase, hornblende, and biotite, with some acces- sory iron-ore and considerable secondary chlorite and calcite, as well as

some Zolsite. About one-half of the rocks appear, in most cases, to be plagioclase, mainly acid plagioclase, The hornblende is the next most important constitnent and oceurs mainly as pleochroie shreds, A large

number of irregular pieces of biotite are also generally present.

Vashed Basie Vuleanics.—The mashed baste volegnies ape prevailingly tirm and compact, and appear, moga eopieally, as. tine

to medium textured, grenish rocks having an andesitie habit They

conti le ist thiwest nh oaned ue thas L tore Taku bores north n edge these

herth

phi cisses, places

ithieult

inely- hated

seen ACCES. rell as to be most large

ATLIN DISTRICT, B.C, iD

have always a laminated stevet re, hever bed they may or may not cleq long their follation planes, but rally break into sharp angular fragmenta

Typical specimens examined under the microscope appear to be mashed indesites, and constat chiefly of plagioclase & emall amount of quartz, considerable fibrous chlorite, some caleits and accessory tron-ore In ome sections distinct traces of a holocrystalline porphyritie texture preserved, in which large plagioclase Phenoeryata have been prominent Fine particles of magnetite are also liberally peppered through the groundmasa,

are

frre Phe Mhieissea are previah to dark ereenish, thie ! thi

tu coarsely textured rocks which huve a decidedts Eneissoid habit

ind in whieh orthoeluse, plagioclase, and either biotite or horn

blende or both, can be readily detected with the unaided ev

Under the Microscope these roeks are seen te consist largely of ortho clase, microcline, plagioclase biotite, hornblende, epidote, chlorite, and accessory tron-ore, ‘The feldspars vary considerably in relative amounts; in some specimens the alkali feld-pars predominate, but in others the lime- alkali feldspars constitute the greater portion of the rock mass. Chlorite and epidote as well as goisite are generally prominent, and in tions the original ferro-magnesian mins rals oes been entirely replaced kenerally, however, varying amounts of biotite and hornblende sty tain,

SOMME ser

re

Serteite NSchists,—-The sericite-schists are light

ures tinwile rocks whieh are generally somewhat soft and friable, and have pre Vailingly a bright, glistening, appearance, due to the great amount of sericite they contain. In places these rocks contain considerabl iron-ore which oxidizes and givy them a decidedly reddish eolour

Microscopically these schists are seen to consist mainly of quartz and sericite, but contain als, some erthoclase, plagioclase, and sec ondary cal- cite. The original feldspars have been for the greater part alkali feld “pars, and are largely replaced mainly by sericite and to some extent alse by calcite, The rocks appear to have been mainly rbyolites that have

been mashed and sheared, and so transformed into their present fori,

(Qutrtzites.—The quartzites normally are light greyish to almost white colour, but are in places stained reddish by limonite. These rocks ive generally a fine gneissoid structure, and megascopieally

appear to consist entirely of quartz.

Thin sections examined under the microscope, however, are seen to consist chiefly of irregularly shaped, quartz grains, intergrown with which are some of alkali feldspar that are much altered to sericite 4 few graing of plagioclase also occur, but are mainly transformed to cal- cite, Numerous shreds of brown biotite, as well as some aces ssory zircon and magnetite, were also noted.

Limestones.—The limestones vary from white to light-bluish,

and from suberystalline to crystalline, and ean generally be dis-

28627—7

50 GChOLOGTOAL SURVEY, CANADA

tiiguished for a long distanee on aeeount of their light) eolour Ti places they are somewhat argillaceour, but are more frequently iewots in composition They generally oecur in massive beds 10 te OO feet in thiektiess, but in seme places, where considerable

icliminoure of argillaceots tiatter oeeur, they become somewhat

“thie Tt HEEL ANTES

Vt these schistose aud gneissoid rocks of the Mt, Stevens group have been subjected to folding, faulting, mashing, shearing, and distortion, and have been so metamorphosed that in many places their original characters have been masked or even totally destroyed Even the limestones are folded, crumpled, and so involved with th vtler members, that their relative ages are uncertain.

These rocks invariably occur along the eastern edge of the Coast Range intrusives, and wherever found in Taku Arm belt,

vonstittite portions of the walls of the Coast Range batholith

Veal VN 8) ¢ ORME E ATION

In Taku Ari belt no fossils have been found in the members of the Mt, Stevens group, and it is only known that these comprise the oldest rocks exposed in the area, Tlowever, from the descriptions of MeConnell’ in Dawson distriet, and of Brooks! and others in Alaska, it is evident that the Mr. Stevens rocks correspond with the lower Paleozoic terranes of those districts, Ditferent members of McConnell’s Older Schistose Rocks’ are lithologically apparentls mitite similar to those of the Mt. Stevens group. The gneisses appear to correspond to the Pelly gneisses,” at first considered to be \rchwan, but now believed to be much more recent, and probably Palwozoic, Certain limestone bands carrying Silurian fossils oceur intercalated in the schistose rocks in Alaska, and these limestones,

both in their asseciation and oecurrenee, resemble those in Taku

‘McConnell, R.G., The Klondike gold fields,” Ann, Rep,, Geol. Surv., Can., Vol. XIV, p. 17. 1901.

Brooks, A. H., “The geography and geology of Alaska,”’ U.S. Geol. Surv., Prof, Paper, No. 45, 1906, pp. 208-218

*McConnell, R. G. The American Geologist, Vol. XXX, July, 1902.

colour jently wale 10

he rable

pew hat

wreotp g, and places troved th thie

of the i belt,

th

enibers TEP OP hme iptions ers an 1 with embers irently appear to be robably stones,

Taku

\rin bet The Mi. st group lererd te & Fs Devonian, and pProtuehl ill ‘ ’

The name Mt Stevetia gf Pp Whe ret tet hea , tlistriet,' Yukon, hepe the Fim iter Tr aively In the Sriter report s th Lewes ted Noopebes Rivers al area, Yokon, rocks are aleo dew Pileed tider tl tt

Razor Mt. group hat in all proba f Preeti tye! the We Stevens Croup t theet etal y rarle ma ferop coeur ther rrelat i omewhat uneertaiy

The nv Moers tie ded uteder di bston IX on Pred

(iw map, and in his report’ on Attin inbining distriet, ales Presperel te those of the Mt. Stevens gre Taku Group. DEST HIBE E}ON Outerops of rocks belong hw te the Paku wee po are ditnitedd

Taku Arm belt to three stall sreas, the largest on the northern end of Penin ula mountain This

miles long in a northwestern direet{: nh, and has an

average width about one-half mile. The Taki rocks alse occur throughe i) Area possibly three-fourths of t mile in diamete r. Sititated at the eeitl “astern corner of Turtle lake. and thu thout 24 miles in a ith

easterly direction from the larger area A third stall area, appar

ently only a few hundeed feet in diameter, oceurs on the south shore

of Taku arm, opposite the mouth of Tutshi river, Owing tet]

presence of superticial deposits the size of the two an aller areas is

only approximately estimated

1 Hologioal Characters,

The members of the Taku group in Taku Arm belt are ma

cherts and slates. The cherts range in colour from '~ht and dark

urey to black, but in places they are reddish on weathered suplacs due to the oxidation of small amounts of contained iron ore, These

'Cairnes, D. D., “ Wheaton distriet, Yukon,” Mines, Memoir No 31, 1912

*Gwillim, J. C., “ Repert on Atlin mining district, British Columbia.” Geol. Surv., Can... Ann Rep., Vel. XI, 1899, Part B, p. 16

28627—74

Geol. Surv., Dept. of

o2 GCROLOGICAL BURVEY, CANADA t i tt se it i f tha i ! froailael Kaperd, fragtuents Phe Pig: f th ‘ rt ie thet fefinitely determinable fron theie lLthoalogien! charaeters, but ine the OUR beret f lesa thtitnately a iated with the alates f th Fuku Av reertap, the rte thesaght be probably, for the wereater pure en highly metamorplemet! silieeous sediments typieal they f theese heret wa itulvyeesd by the Mines Plraneh of th Dopartiment Mir howing the rork to eontain oa fell a0 96.2 Vie 118 Pea 6 Pet ov Myth trace Minti trace fat) trace Naw O08 KO Om HO cat tle oe} trace HO tabowe Te ¢ Oo TW oe% Pt) oat co Organ hatter mall pereentage Potal 7.76 Bperitie gravity 266 , . ' ij , This alse indicates that these ¢ herts are of purely sedimentar origin

The associated slates generally Postega a well developed slaty structure, cleave readily into thin plates, are dark or nearly blac! in colour, and are folded, broken, and distorted

Age And Correlation,

The rocks of the Taku group underlie the Carboniferous (7) Brae- burn limestones and appear to correspond with the members of Dr Dawson's Lower Ciehe Creek series’, of more southerly portion. of British Columbia; they have, therefore, been considered to be probably of Devonian age.

These rocks also occur in Windy Arm distriet, Yukon’, and were there referred to the Lower Ciche Creek group. Since, how-

‘Dawson, G.M,, Rep. of Prog., Geo!. Surv., Can., 1876-77, pp. 55-58

Dawson, G,M., Ann. R p., Geol, Sarv., Can., Vor, TIT, Pre B, 1887 88, pp. 170-179

Dawson, G. M., Ann, Rep, Geol. Surv., Can., Vol. VIT, Pt. B., 1894, pp, 37-49

*Cairnes, D. D., Portiona of Conrad and Whitehorse mining di triet.” Geol, Surv., Dept. of Mines, Can., 1908, pp, 26-29

ATLI Pisthter, B. ¢€

ever, thie correlation Hhatrle etitively trom De. Das tions and without the wrier having secon the

Creek roeks, it seen possible that th oe

cortespond, and the new name Taku epeus ha th wlepted in Taku Arm belt

This group corresponds to division VEEP on Oh

and im ? report on Atlin minin eliatriet

Braeburn tis Hes syerernny the entire nmeorths

f Taku Arm belt and are extensively developed thenes

ind east. They thus extond up Taku arn the mouth

river on the west shore, and continue southeasterly + northeastern part of Pesinsula mount tin, and the hills

to the east of Sunday peak

LETH Omst AL CELAMAG TE HM

These limestones are gone rally tinely texture and r from greyish blue to almost white Phey alse vary

talline to crystalline in structure, but are prevailingls

of marble, and tany specimens are handsomely and curiously ma

with grey and black lines and spots. Some beds eontain consid

silica and weather rough, and occasional layers particularl

the bottom of the series, are composed largely of cherty mut

These limestones are over 3,000 feet in ieknesa, and heavily bedded, and eonmicde rably metamorphe od

rare cases are definite bedding-planes disting <hable

Age And Correlation

The name ‘ Braeburn limestones’ waa first applied

burn Kynoeks area’ from where these rocks have been

tinuously to Taku Arm belt. These limestones are also

aa those ineluded under the Upper Cache Creek sepies

wia deseriy Loweg Chobe ab togrert he effete erty witlirn map, tern rt to the port of Tuteh o inelude the minediate| Hee iti ool trot ber

iti tite aire genera that in on!s in the Brae traced con the aan

f Conral

*Cairnes, D. D., “Preliminary memoir on the Lewes and Nordenskiéld

Rivers coal district, Yukon Territory,” Geol. Surv., Dept, of Mines

Memotr No. 5 1016 pr, 29.40

Can,

‘ t aA SERA ' i Ph i ty f eo a bree bie f bevel t tt t tipper ¢ Cres ‘ He h tal ; Wis made entipety Peet i Pif ' i f ! i t ' bate ' tt breve I th h t i fal pat i VW et f t f t f : thee # aefies tarhit pe thi . ' Pevrre ' ? ’ t ' fevl Perkina Group Ps PHBE Ti Lair i i ferve thevtet the members the Py t tel t 1 thes re all wittiates| rth t Ft ti larivest apea cen ita 1 t h t rti ‘ ill j ‘ pretrentily ty the MH) feet in chameter Appears ‘ tt rt t ot Cup ttilet t © pith weat of Tuky I i i th rel amall ive i t WE Fever t Hifthetog if ‘ t th western roer of Stnday mountain fourth devel LU t Hithes long inom 4 rthiesterly direction by one hal tithes Wiebe. The th of ‘Hit mountain; and a considerable porti f the extrem evitlied end of Peninauta Mevntain iteelf drier these ¢ hire HOTA, CRLAHACTEIS li ereibers f the Perkins gre ip Cots ehietty iidesites rlesit ff Habise, di rite, and magnesite andesites and Andesits T ufhs The andesitie membera have leritiffedd orbs h Penineula mountain. nd are there for t reater part heayi rou-stained and considerably: dees Imposed Dawson, GA WOR of Pra ti ' Car WATR.77, op 8 Dawson, GQ Moo Ann R Geol 8 Can vl. Sit. Kh, IS, pp. S749 Dawson, GM Ann R Geol Sur Cc ISS7-84, pp TOT

1h, OM

; ; ; rely i lh places th , t f Pu byte f tuff ti This ti i L ' re fie f thee evi ft ‘ t l # t F I i fi th the ¢ ‘ Mics pieally the ate oh te pert ‘ ‘ ; P t yp! feluse, hornblencte i boiotit wit . trefaliine er heloerty talline groutedn i feldspar of the firat eration preva lingty labraderite, but hig f honts te betewnit ated shitite (Winning a eerdis te th thee he t¢ hart ta /anal structures are alan of frequent urret ad represent vaviatior sMHonnt Of lithe preset The ¢ ‘ ‘ lant a Pinel fel fafige if ee fF fe fF t ' ther fan inokh long, Comer , bile ' tt nt of the coloured conetituent stl ger ' ‘ Hoot . tially ¢ uw" ciated with tt rniblene hat ' ’ t ol fer romeagte ah) im t te ft ros mw rhtle f ry apatite ati magnetit fri Pree The pgreundma has frequen! pileftas:t fa ' t f I f ke wel plawiorlase need] hernblencd snd r Fel ote grait (Hfen a rtain mnt of i ' th ther materials giving the groundmass a hvalonilit t 7 i The roek coneatittient. at th Eerst eyes heicerab sit t ks consist fo a great extent of chlor prebote t t " jartz, ane trom ore which latte ' : bet i ' hroughout the groundma These alterat featu #1 ' te Hiatingnish these rocks from the Chieftain FLL welear ty Dialane Dishase wae found only in he te trial ifen, u it MM) feet in diameter # Sunday mountain ind ie a ma ve, firm

lark greenish t rrevishogres medium textuped, r that megaaeopieally seen to he holoerwetalline ind te eonaiat largely f plagive'ase and a dark ferro-magnesian mineral 4 Under the Microseane the r pre he composed large brat plagioclase, uratite, chlorite, ge ‘ tprtite, ilmenite and’ ifs alteratior prednet leteoosene ind magnetite The greater part ¢ tt t ma onsets of plagioclase and uralite, with alee consider echt te I e rock prosteases quart 1 tlecidest ophitie structu ariel ‘ name cdttbase t Diovit Diorite waa found in Ta Arm belt u loealitv whieh j witttated pust west f Table n lnital Th : i ' megascopically, a holoerystalline, granular, grevish to grevish green, , homogeneous, finely textured rock in which feldepar and hornblende

ite distinetly visible

56 GEOLOGICAL st RVEY, CANADA

Microscopically this rock is seen to consist largely of plagioclase, horn- blende, wugite, chlorite, and accessory tron ore. The greater part of the rock is composed of plagioclase whic hots prevailingly in allotriomorphie prismatic pieces, The hornblende occurs as numerous long brownish shreds with indefinite terminals, and also as diamond shaped idiomorphie to hypidiomorphic Brains. A few auyite individuals oceur but are ygen- erally much altered, mainly to epidote. The chlorite is largely derived from the amphibole,

Magnesian Rocks. -Magnesite and related rocks high in magne- sia, occur in two localities, viz., on the north shore of Graham inlet 34 miles west of Taku Landing, and immediately to the south of the southern end of Peninsula mountain, These rocks weather rough and are, in most places, heavily iron-stained. On fresh frac- tures, however, they are grevish to dark greenish in colour, and are seen to be finely textured, and to have generally a schistose structure A considerable portion of these rocks, and in places bands several inches wide, consist of almost pure magnesite,

Under the mic roscope these magnesian rocks are seen to consist mainly of plagioclase and magnesite. All the feldspar has wayy extinction, and exhibits a consertal fabric, the particles heing interfingered together. The magnesite shows a decided tendency to he crystalline, and has domin- antly largely a consertal arrangement. The rocks also contain subor- dinate amounts of calcite, dolomite, epidote, and iron ore, and have heen

mashed and given a histose structure They all appear to he much altered igneous intrusives high in magnesia,

Age And Correla’ Ion,

Concerning the age of the members of the Perkins group, it was only detinitely determined, in Taku Arm belt, that they are all younger than the Mt. Stevens froup whieh is considered to be pre Devonian, and are older than the Jura-Cretaceous sediments and Coast Range intrusives. The Laberge series contains many pebbles of the Perkins rocks, and in several places the Coast Range granitic rocks were noted to cut them. The rocks correspond to the Perkins group of rocks in’ Wheaton district, Yukon,? where the name Was first adopted. The andesitie members also are probably of the same age as the rocks in Whitehorse district deseribed by MeConnell as ‘ Porphyrites?? and Which are more recent than the Carboniferous

limestones,

'Cairnes, DP, D., ‘‘ Wheaton district, Yukon,” Geol. Surv., Dept. of Mines, Can., Memoir No. 31, 1912,

McConnell, R:. G., “ The Whitehorse Copper helt, Yukon Territory,” Geol. Surv., Dept. of Mines, Can.. 1909. pp. 9-12

Atlin District, §, ©, 57

The Perkins rocks also correspond close ly to the Gold series’

described by Gwillim in his report on Atlin mining 4j triet; th Gold series, however, uppears to include under greenstones, andesitic rocks which are more recent than the Perkins rocks and are in this memoir included under the Shieftain Hill voleanies

In the writer's report on ‘ Portions of Conrad and Whiteliors mining districts,’ rocks corresponding to members of the Perkins kroup are included in the Lower Cache Creek series, considered as being of Devonian age; but since Mr, Met ‘onnell’s work in White horse Copper belt, it appears that at least the ands sitic, and possibls other members as well of the Perkins group are post Carboniferous, pre-Jurassic, so all have been provisionally placed under upper Palwozoic. It is Possible, however, that some members, the dinhass or magnesite for example, may he as old as Devonian

Coast Range Intrusives.

Distribution,

All the extreme southwestern corner of Taku Arm belt consist

vf the Coast Range intrusives which also form a considerable portion of the top ef Lanning mountain and the high ridge to the south of Racine lake, Besides these larger areas a number of smaller exposures a few hundred or a few thousand feet in diameter occur In various localities through the district. These rocks also compose the Coast range of mountains lying to the west of the district and are probably the most extensive individual geological terrane in

iorthwestern British Columbia or southwestern Yukon,

Lithological Char Ac Ters,

The Coast Range intrusives are for the most part fresh

unaltered in appearance, are predominantly greyish inc lour, have the general appearance of typieal, medium to coarsely texture granites. The orthoclase is, locally, sutciently prominent

these rocks a pinkish colour, but this is exceptional, In places these iutrusives become porphyritie in structure and contain numerous urge feldspar phenoerysts as much as 14 to 2 inches in length. Hornblende, biotite, and augite. are generally present and are in

most cases readily visible to the unaided eve.

os GEOLOGICAL SURVEY, ¢ LN ADA

When examined under the micros Ope, Most sections of these rocks 4te seen to consist chiefly of alkali feldspar, an acid bime-alkalt feldspar, quartz, hornblende, biotite, and augite. Both orthoclase and microcline severally occur and together are characteristically about equal in amount to the acid plagioclase, ‘The feldspars frequently exhibit zonal structures showing these individuals to vary in composition from the centre outwards,

The hornblende. biotite, and augite are. in typical seetions, about equal in amount, although occasionally one or even two of these minerals May be missing, The hornblende and augite are in places intimately intergrown, and the biotite usnally occurs as large fresh individuals, all these minerals being prevailingly allotriomorphic, In addition, zircon, “patite, and magnetite are frequent accessories, The rocks have either a typical granitic structure or contain large feldspar phenoc rysts in a grani- tic groundmass and so have a holocrystalline porphyritie structure

These intrusives thus have predominantly a mineralogical composition midway between a yranite and a quartz clorite, and have been called grano-diorites In places in the Coast range, with increasing ortheclase

and decreasing plagioclase and wugite, typical granites have been voted; also locally the plagioclase and augite inerease and the orthoclase o.sap Pears, RIVING Vise to diorites, Such extremes were not found. he wever, in Taku Arm belt, Oe- jonally with the introdnetion of a porphyritie struc- ture, these granitic cks might be almost equally well termed either por- Phyritie grano-diornes or grano-diorite porphyries; but since the rocks everywhere are coarsely textured and alwavs have a ty pieal pranitie habit,

the orm porphyritie grano-diprite seeme preferable in all cases. Similarly po ritie granites and diorites may oceur,

A typical specimen of these intrusives was analysed by the Mines

Branch of the Department of Mines, giving as follows:—

sid

Alo

heO

keO

MgO

Cad

Na.)

Ko ;

HO (at 1W0e

HO (above 110.) , Tio

Plo

Co ; Mino ‘ z trace

Total : 1 45, Specific gravity==2°69,

This analysis indicates that this particular specimen might be termed either a caleie granite or a grano-diorite, but under the microscope, as described above, the rock appears to be decidedly a grano-diorite,

The term monzonite has been adopted by the United States geological survey, and is used by many geologists both in Canada

and the United States for rocks midway in composition between

veks par, line ‘unt ires rds. ot roils tely als, ‘on, roa ini-

ion led ise ed; ap in uc- Oor- eke bit, rly

1e3

Ntlin District, B. ¢ 5

tittes or svenites, and diorites hal acer

Hog to this thomenclariue

those rocks are pre vailis

porphyritic quartz monzonites, The name Adamellite has been used b bros ver! as a con

Vetiont term to signify an seid quartz monzonite

In places, as on the northeastern corner of Mt. Cli

ive, ba ferentiation prodiets of the frattocdiorit it IVKes euttin e grano-diorites and the surre nding Laberge beds An averag ne Of one siuely dvke examined tiniele r the Thie Pees Proves bie hornblende Kersantite ane is typiea Hhied 1 aye Consisting mainly of plagioclase, bietit nd hornblends Nha Pagioclase oceurs in long, lathe-Like allotriomorphie or limpid morphic forms of very uniform. size. The biotite and hornblend

occur as allotriomorphie particles scattered between the feldspar which form a sort of web or base containing therm The Klusha Intrusives are probably the later acid differs Nflation products of the grane-diorites,

AGE AND CORRET TON Phese granitic intrusives which eo Hose the ¢ lith, have been studied by geologists in British Columbia Alaska and Yukon, and there appears to he a general consensiis of opini mm

that they were intruded in aout Jurassic time. In Taku Arm belt however, although large pebbles and boulders of these intrusive

eceur in the lowest beds of the Jura Cretaceous Laberge series, yet

wherever contacts have been discovered between these sedimentarics and the intrusives the granitic rocks distinetly cut even the Upper

most Laberge beds, showing that the ( ‘oast Range rocks, although they

are all lithologieally very similar, were intruded at different times, separated by wide time intervals. The greater part, at least, of thes: rocks in Taku Arm belt are more recent than the Laberge beds, all of which appear to be Jurassic or Jurassie and possibly lower

Cretaceous, Laberge Series. DISTRIBU TION,

The Laberge series js the most extensive geological terrane Taku Arm belt, and its

in members outerop in a general way through- ' Brogyer, W. C.—' Die Eruptionsfolge der

nsfolg triadischen Eruptiongesteine be Predazzo in Stidtvrol.’ p. Ol

6o CROLOGIOAL SURVEY, CANADA

out the central, southwestern, and northwestern portions of the district. The group of hills east of Taku arm and south of Graham inlet; the greater part of the area north of Fantail lake and south of Tutshi lake, on the west side of Taku arm; and Sunday moun- tuin and the western portion of Taku mountains, are all largely composed of these rocks.

Lithological Characters,

The Laberge series consists of shales, sandstones, conglomerates, greywackes,' tuffs, slates, and quartzites, which have an aggregate thickness of at least 5,000 feet. Possibly the most conspicuous members are greyish to greenish, finely textured to medium grained, homogeneous looking, massive rocks, which in many cases exhibit no distinct bedding planes, except when viewed from a distance, and are in places with difticulty distinguished from some of the Chieftain Hill voleanics to which they appear to be directly related. These beds constitute the greater part of the upper portions of the Laberge series and occur, also, but to a less extent, lower down. They are apparently predominantly pyroclastics but grade into ordinary water- laid sediments. Associated with these greenish rocks, in places, mainly in the lower third of the series, are numerous beds of dark grey to almost black, generally friable, shales, accompanying which are numerous bands, generally only a few inches in thickness, of tinely textured, brownish sandstones.

The middle portion of the series is characterized by shales that are in most places heavily iron-stained on weathered surfaces, and can be distinguished for long distances. When broken, however, they are generally seen to range from light grey through dark green to almost black in colour, and are hard and brittle. and break generally into sharp angular fragments. They oceur prevail- ingly in layers one-fourth to 1 inch in thickness, and are associated to some extent with greywackes and sandstones, but ihe shales pre-

dominate.

‘In this memoir the term greywacke is intended to include consolid- ated sediments consisting mainly of prevailingly angular fragments of feld- spars, quartz, mica, and perhaps hornblende and angite, as well as of various rocks, all in a groundmass having about the composition of a clay slate. The term sandstone, on the other hand, includes those cons lidated sediments that consist largely of quartz grains |ound together with some simple cement such as calcite or silica.

the am ith

ithe

ely

ATLIN DISTRIE Far ee SS,

Le low the reddish shale horizon the be freenish greywWackes and interealated clark rey ft

soft, somewhat friable shal Near the bert

characteristic, course Conglomerate by Is, the

boulders of which are intinly granc-diorite, lin eat e, and

igneous rocks derived apparently from the Perkine rrouy

6 to 8 inches in diameter are of

MMON occurres ind son ver hefed as much as 24 feet long In the vicinity of intrusive rocks, particularly the t Ra intrusives, the Laberge beds boeomae hard, ce Nee, dthart ied cherty. On Mt. Clive, Mt. Lanning, and elsewhs te, tor over 50 fer

from the granitie rocks, the Laberge beds ar distinctly erystalline

ind in places hard and quartzitie. In plices, al o pressure has alreg

the shales into true slates.

Under the microscope the greenish,

medium text Ired rocks are Set 'o consist largely of angular fragments of feldspar, hornblend biotit tugite, quarta, and voleanie rocks, and also contain particles of iron or In some specimens there has been almost complet disintegration of t4 varent rock into its component minerals, but in other places this procs 18 less advanced, With increasing amounts of yol

hie materials th fragments largely of vol its of feldspar, quartz, hornblende. weur In a voleanioc gr The rocks that consist largely of mentary materiale are elas as grevywackes, but where the vol matter predominates they are ¢ asidered to be tuffs. In places these y "re greatly altered mneinty to calcite, kaolin, and chlorit.

rocks grade into distinct tuffs in’ which rocks, but also of v.

MODE OF ORIGIN, Considerable portions of the Laberge series are undoubtedly

onlinary water-lain sediments, but voleanie fragments are it

In plae very plentiful and increase in amount in places, to the almost omp exclusion of the sedimentary materials, It appears probable that vuleanism was active during Jura-Cretaceous sedimentation,

that showers of ashes and breecia fell into th and beeame both directly and indirectly associate with and water sediments. Some of the I the

and e sea and on the land, le land ziberge beds were deposit 1 in sea, as they contain marine fossil remains, but portions appear to have been d posited

considerable on the land largels

stream-action. These beds are characterized by occasional isolated

und widely separated pebbles, up to several inches long, included in

a fine groundmass, Pebbles in sea-shor deposits invariably occur

close together and are of somewhat uniform size, due to the sorting

action of the water.

GROLOGIOATL SURVEY, CAN ADA Gh ASD CORRELATION

Fhe name Laberge series was tirst applied in the Braeburn- Kynocks coal area,’ where beds oceur very similar to those in Taku Arm belt, and in these a number of poorly preserved fossils were liseovered which were examined by Dr. Whiterves, who elassed them as Jura-Cretaceous These beds are overlain in the Taku Arm belt by ‘Tantalus conglomerate from whis ho plant remaina, determined to be of Kootanie age, were collected This would indi cute that the Laberge series ure entirely Jura ale,

In Wheaton district, Yukou, numerous specimens of Prioneyelug woolgart have been found in the shales on Mt, Follé and Idaho hill, of which Dr. Whiteaves said: ‘Prioneyelus woelyari (Mantell)—several crushed specimens of an ammonite, that are possibly very young individuals of this speeles, Tn the upper Mis. sourt country, and elsewhere in the United States, P. woolgari is regarded as a characteristic fossil of the Fort Benton group.’

On Bee peak, in Taku Arm belt, a few poorly preserved speci- mens of 2, woolgart were also found,

The Laberge series, together with the overlying Tantalus eon- glomerate, correspond to division IIL on Gwillim’s map, aud in his veport on Atlin mining district’ Gwillim collected fossils T. W, Stanton write

from these rocks on Atlin lake, of whieh Dr. ‘These may possibly be Triassic, but L think it more probable that they are carly Jurassic. They are certainly not so late as the Cretaeeous,’

The infor lation concerning the age ot these be ds is thus very fragmentary and to some extent conflicting, but the weight of evi- dence seems to point to a Jurassic age for the greater portion, at least, of the series. Until more information is obtained, therefore, the series muy best, perhaps, be cousidered as Jura-Cretaceous.

The Laberge series also probably corresponds closely to Dr. Dawson's Jackass Mounts! group’ whieh, however, appears to inelude the coal-bearing Tantalus conglomerate, These rocks are

*Cairnes, 1). D., “ The Lewes and Nordenskiéld Rivers coal district. Yukon Territory,” Geoi. Surv., Dept. of Mines, Can., Memoir No. 5, 1910. a : willim, J. C., “ Report on the Atlin mining district, British Colum- hia.’ Geol, Surv., Can., Ann. Rep., Vol. XIT, 1899, Pt. 3, pp. 23-27

Dawson, G. M., Rep. of Prog., Geol. Surv., Can., 1875-76. pp. 253-

Siti itt fije

Ieee at part oof Poe D I’ includes great amounts ot viel ‘ to the Chieftain Pht Y Ml Leael ‘ rill Porphyrite sepic in the Butkh t SKeena RR district has wiven the imat Tf Tantalus Conglomerate. bist win Only one small ONprostry ' therate w : th Taku Arm belt: this oc 1 i mmit ont ith side of Graham inlet about + Mitte ei thwe Peku Las Hi, atid jst more than a few hundred foot in ttiete Similar ks als hear Sloko lake shel prota t

LUT Opem te yt. ¢ tAl f Puntalas Obie torerute: Leved hh t tl I ' Inerate, the CoMmpotiett pobb les Which ape itz, chert ; hese rocks ean thus be re udily listing shod frets othe r rl

erates in the distriet, all of which contain pebbles of vari Material

such aa, limestoy 8 granitic rocks, voleanic rocks, ot The Tantal conglomerates ape prevailing homogeneous in appearance, dark jt colour, and even in texture, the component pebblea bel § rarely over

2 or 3 inches in diameter \ssoeiated with, and int realated in thes conglomerates are a few

shale beds, and in most ither places wher

any considerable portion of the cong omerate section has been seen

coul seams have been found.

In Tantalus esal area the

On omerates ure over 100g feet in thickness, but in Taku Arm belt erosion has rem ved all but about 30 feet of the beds, and the pertion remaining does not contain eval rhe great thickness of thee conglomerates, alone js a strong jd eation that they are continental leposits,"

Dawson, G. M., Rep. of Prog., ho DP

‘ , , 5-72 Leach, W. W “The Telkwa river ard vieinity, Ba Sury Can, 1907, pp, 10, 11, Leach, W W.. Sum Reports, Geol, S irv., Dept, of Mines. ¢ aq 1907, p. 20; 1908, p. 41

Leach, W. W . Sum. Rep., Geol. Sup Dept p. o4, Barrell, Joseph, “ Relative

littural, and marine sedimentation.’

of Mine Can,, 1910

importance of continental

of Geol, Vol. XIV, Nos. 4

ot GEOLOGICAL SURVEY, CANADA

Veh AND CORRELATIONS

No fossils were found in these beds in Taku Arm belt. but the overlie the Laberge rocks, apparently eonformably

Phe name ‘Tantalus conglomerate was first applied in Tantalus coal area’ Where these rocks are of considerable economy iM portance oh aeeount of the coal they contain. Fossil plants were collected from the eon tims at the Tantalus mine, and were examined by Dr. Pentiallow, who mas All the specimens from the Tantalus mine present a flora with the same facies as those from the Norden+

Kd river, and the whole conform to the flora of Kootanie ae

Pantalua conglomerate oocurs in: Wheaton district rege oree ontiitia Valliable seats of eoal,

A conglomerate having the lithological characteristics of thie Pantalus conglomerate cecurs in Moose Mountain district,’ Alberta, and is there considerod to be the lowest member of the Dakota formation, and directly overlies the Kootunie which contains the tnost Valuable coal seams of the district Phe conglomerate ther generady from 10 to 40 feet in thickness

Similar conglomerates have been found by Me, Leach! in Bulkh Valley associated with valuable eoal aw ams, but ure there over vor feet im thickness. Similar conglomerates and possibly of the same ite have been deseribed by Dr, Dawson and included in his Jacka Mountain gr indd Porphyrite series, referred to under Laberg: series These beds thus appear to have a wide distribution in British Columbia and AUberta and to increase in thickness towards the north,

Chieftain Hill Volcanics. DISTRIBL TION, The most important development of Chieftain Hill voleani occurs as a northwesterly trending belt, 1 to 6 miles wide and abou:

miles long, extendiag from the southern edge of Table mountain

*Cairnes, D. D., “ Preliminary memoir on the Lewes and Nordens- kidld Rivers coal district, Yukon Territory,” Geol. Surv, Dept, of Mines, Can., Memoir No. 5, 1910, pp, 35-39,

*The Koctanie is by some regarded as lower Cretaceous, but is gen

erally ussigned to the Jura-Cretaceous, and js considered to be either lower Cretaceous or upper Jurassic. *Cairnes, D. D., “The Moose Mountain district, Alberta.’ Geo!

Surv., Can., 1907, pp. 31-33 *Leach, W. W., Sum. Reports, Geol. Surv., Dept. of Mines, 1907, 1908

it

bia bite oh CnPuhanmi cilet Paka arm Phe on @xeupt as dvkesa, ineluchew nit of adjoining peak to the nort j ‘

Lhe Chieftain Lil vel ire 4 siiwite ndesites and atielesit tufl sitlePubiy in Ppeu tiation il j rev, lie, wreet, atid by li, bith ye ri

distinct porphyriti truet

teerysts commonly of feldspar and

itd biotite are ge herally visible. On however, dark-greenish dletise, — thtvel

occur in whieh mone of the u ral eon disecrnible. These rocks close resem

anee and composition, and frequentls

Jointing (Plate XXIV). Rocks with a wresish, or gteenish, groundia in wh ire prominent are the commnonest type and Bar mountains truetures are Tutls and breecias ire of Wide-spread

Texture from microseopic tufls, to coarser

frigments several feet in i

Hneter eee

tain im places ao con iderabe admixture

' . r ! mer Mounfuinh btied ff tly tea hotublende-, and ‘ i iy ¢ Ww link bitte tikes! ‘

fe is prevailingly noticeable, and

iu rure t her

thi if itain and elsewhere, ‘ reel ipl icles ite t deta i wii te i t alt th in appear ith PPoMmnent Prietnats

dense, aphanitic, reddish, sell formed plagioclase In places on Peninsule preserved t oveurrence and vary in rocks in whieh individual Phese clastic poeks cor

foreign materials an

‘ppear fo pass gradually into the Laberge tuffs ind groywackes In places the Chieftuin HH hics 80 close resemlil ‘ andesitie members of the Pork froup that it ditheult to d Tinwiish one from hie The Perkins po ire generally t] more altered of the two, but in places there is not this distinetion Microscopically the Chieftain Hil yolea r en to have a e siderable range in structure and 1 ineralegical composit but eor chiefly of plagioclase, occasional ortho lose, hornblende, biotite, and d side. The plagioclase is the chiet mponent of th and nce) in both generations. The plagioe’a phenoerysts range from an ' bytownite, and are generally well ; d andtwinned acenr ling to ti albite and frequently the Capla! Wand perieline laws as well: gonal tr tures are also plentiful. An acid plagi is alwa nt} 1 Mass and is prevailingly andesi hut ol ! t ‘ 1 . Varictics also ceeur, Orthoclase hoted e Hhadet and is frequently present in the groundm M rerthit but is rot at alf a charact t oi stit t € k

P8G27 ..8

Heth yient tered it ith bietit Rrown biotite focka aa th

present

Haron

but

although ite to he

only fefreo hero pant

quently ooetra ppered

t + obundant, bat be not as atit

tfe alee The minerals de, and

ommon

focka are ale

and he prevails ' Varies ts ae t ‘ holoervetal rare i tltin ta tructure seteristi nbn ' ‘ ney tthe tt the apy

ributed, and filled itm hetween ' In places a certain amour

the structur

ur ha

ed ment

iry mate !

Klusha Intrusives

(bho bemebo vt ANADA

typieal specimen from a dyk south side of Craha was unilvsed by the Mines Branch of the Department she wing the rock te be composed of the following

sie

Alo

Feo

eo

Mut)

Mn

Cao

Na.

Koo

Ho Oat lie

HO above Hac

Two

ro

The specitio gras ity

Nep Corre Dn Tton

The Wlhisha iutrusives are very reeent and, with the exception of the unconsolidated Quaternary deposits, may be the newest

- in the district. Whether they are r or me r than t Carmack basalts is not known, ‘They are, however, closely related fo the Wheaton River volcanics, differing from them chietly in texture. It is thought, therefore, that beth the Klusha introsives and th Wheaton River volcanics may belong to the same period of igneoit activity; if se, the Klusha rocks are more recent than the basalts,

The name Klusha intrusives was first employed in Braeburn- Kynoeks eoul area, to represent aoseries of svenite porpliy ries that much resemble the syenite: and granite-porphyries in other portions of Yukon and northern British Columbia, Similar rocks have been described in the writer’s report on a Portion of Conrad and White- horse mining distriets” under the name granite-porphyry. and in that district were found to pass from granite- to syenite-por-

phyries without any marked difference in their general appearance

The Klusha intrusives are also desevibed in the writer’s report on Wheaton district.

Carmack Basalts. DISTRIBL TION Carmack basalts were noted in Taku Arm belt in only two localities, the more souther], of which is situated on the west shore

of Taku arm south of Fantail river. There these rocks ar

ipparently develo; tlong the shore

one-fourth to one-halt thwest

corner of Armstrong peak, Where ek lt nin te i

area about 1000 feet in iat

LITHO oe

The Carmack basal wn aphanitic groundmass thr f olivine, and augite, ean often ure, in places, sufficie ntly large and mediim textured, granular, Uppearaner of these rocks are main y tuffe and b in size from tie rescopie tad of Kirtland, just hoof the

PoeRs ure predotud ntly tuths and i)

Microscopically these rocks are se n to be typ pot structure and to consist largely of Plagioclass augite d olivin becasionally considerab accessory iron ore. The Plagioclase oeour both generations, the phenocrysts being prevailinely diverse-tabular form and embedded in a groundmass composed mainiv of Plagioelas

augite, and olivine, with their alteration products, ‘The aupite phenoery are large, idiomorphic, and generally but slightly altered. The ivine partly, and in places entirely replaced mainly by serpentine, but also some extent by calcite and iron. The olivine and angite phenocryst prevailingly much larger in size than the teldspar

Hand Correlation,

No evidence is obtainable in Taku Arm belt oncerning t]

age of the Carmack basalts, except that they pierce Carboniferous

limestones. In Wheaton district, however, they intersect

tain Hill voleanies and are in turn cut by the Wheaton volcanics, They have been described in the writer's rey ‘Lewes and Nordenskiild Rivers coal district’ where the Carmack basalts was first applied, and also in the report *On portion of Conrad and Whitehorse mining districts’ under term *scoria and basalt. McConnell has also described th

in Whitehorse district, under the nai “basalt.” In all the

the basalts are seen to be pre-glacial, but to have owed into. deposited in the valleys after these had been eroded to almost present form. The Carmack basalts thus Appear to

Tertiary or Pleistocene age

Wheaton Rive: Volcanics. STH

Arm bet main prevailingwis £0 toe Zo feet in thiekness Sever if cond

these dikes were mote

mothe eastern porti n ot Taku motuntait ind one development approximately 500 feet wide at the immed BOO fee

one-half mile Littl

Phe Wheaton River voleane al Arm belt are tiainly rhvelites in which white to light grey col prevail. In places, however, they contain pyrite which oxidizes, giving them a bright red to brownish er yellowish red colour. These rocks have characteristieally a felsophyrie groundtass in which phenocrysts of

orthoclase, ane ovcasionally plagioclase oceur, The quartz frequently in distinet dihexihedrons which are as much as of an inch in diameter Well formed meyaphenoerysts orthoclase and plagioclase also oecur, but those of the alkali feldspar ore plentitu The rocks when considered as to their relative amounts of phenocrysts and groundmass might be described as varying from perpatic or those extrem ly rich in vroundmass, to dopatie, in which the groundmass is dominant.

Microscopically tl rhyolites are 6% ays have a porphyritic tructure, the phenocrysts bemg predom gascopic and consisting of quartz and alkal and lime-alkali telds, hoclase is cunsiderably the most abundant mineral of the first ¢ von and occurs in large diomorphic forms which often exhibit Curisbad twinning and are fre- quently much altered to muscovite. Quartz exists mainly in 6-sided t-sided forms which are often consi lerably corroded. Large acid pk lase individuals are o¢¢ asionally present and are gt nerally much altered to kaolin and quartz. Accessory iron ores are also commonty present and apatite and zircon occur.

fhe groundmass 1s generally holocrystalline, although in some instan- ces it is hypohyaline and might then be deseribed as ranging from per crystalline (extremely crystalline with some glass) to docrystalline dominantly crystalline). The fabric of the groundmass 1s characteris tically micropegmatitie, and beautiful intergrowths of quartz and feldspar are seen, representing the crystallization of eutectic mixtures of these minerals. Muicrogranitic fabrics also occur, but are less common than the micropegmatitic. In such cases the groundmass is holocrystalline gran ular, and consists chietly of quartz and alkali feldspar

Age And Correlation,

The Wheaton River voleanics are the most recent, consolidated

rocks: in the district, except possibly the Klusha intrusives

ah it sthee th it i yMposition nel lithes ! P

hey re hear 1 t I

The name Wheat ! Wheaton

trict re ft ! t

!

hacia vit to have eome into ¢] ill t 4

i been in ised t Itoet pre t t

t f Jat Pertiny F f

Quaternary, rH

All the main vall the district are thore| ‘) ! eposits wile Wh paces I Con lerable t 1 The I V thick in fact ty Cause reversed - mes, Tnpoumling wrest water. All ihe lakes of the district neluding ‘Ta rm, are tiel| position hy dams of this kine. These deposit ip t whe re in the lowlands or flats ny t tl i places appear to be 100) feet or more in thickne 1 frequently out-crops through them. The Pleistocene mater well up the valley walls, and in places reach nearly or quite t tea surface, The terraces noted near thet t f Tuts) ! H elsewhere, appear to be composed entirely of Pleistoeens deposits A thin mantle of Recent materials ecovera thes irfaee of the 5

nearly everywher no osteen stone nd ¢ rome. LIPHOLOGIO ME CHARACTERS

The Pleistocene and Recent terranes of the district. are logically very similar, and grade into each other to such an extent

that it Is, in places, dificult to distinguish th m. The Pleistocene deposits consist chiefly of gravels, sands, silts, and

houlder-clays, and as these have been only slightly dissected in most places, cross-sections of them are almost lacking: genera ly only the surfaces of these materials are to be seen, but little erosion having occurred since Pleistocene times, In places, however, it could be seen that the deposits of unsorted morainal materials and boulder-

clays, as well as sands and silts deposited in streams and lakes, were

of considerable thiekness.

Grologiocat, Survey Anada

Reeent deposits are composed of glicial, thivial, and littoral,

ind graves produced by the present streams and glaciers

ground-ice, peat, muck, and soil, The sands, gravels,

expo od long tlie presen t ith lakes, rane

inh many places persistently present a few inches or a

few feet beneath the <urfaece Peat and muek oceur mainds in the wide tlats and uround the lakes, whieh lie in poorly drained portion fo the valleys and henee are favourable localities for such aecuma

The glacial silts, such as those which are at present being le

lations posited in the tlats at the head of Taku arm, are quite similar to the

Pleistocene silts; and the other Reeent glacial materials forming

along the edge of the Coast range are lithologieally almost identien with the deposits formed in the early Quaternary. A thin

of soil constitutes the uppermost dene in the valleys, on the up-

laver

ane, abd, mm Wwaices, on 1 Valley Wi + thie mountain slopes. land, and, in pl the vall Is and tain sl

Economic Geology.

General,

Placer-gold) was first mined on the Atlin creeks early in the vear ISOS, and since that time this industry has been the mainstay of the town and surrounding district. During these vears a certain amount of attention has also been paid to various quartz discoveries, und recently those interested in the welfare of the camp have begun to hope that this class of properties may continue to produce after the gravels have become exhausted, and so prolong the life of Atlin as a mining district. Although a complete diseussion of the economic veology of Atlin district would primarily treat of the placer-deposits, for the reasons given in the introductory paragraphs of this report, this chapter will deal only with the non-placer mineral occurrences, including the ore deposits and coal not only of the Taku Arm belt

that was surveyed during 1910, but of Atlin district generally,

For convenience of description, the non-placer mineral! deposits

may be classified as follows :—

One Per

OO) Ceeodebets luriuen ‘jliayt I (h) Gioldesi] er quart ve (©) Cupriferon Wer-pold vedt

@) Silver-lead vein (ey ( opper vein

/) Antimony 4

yy

Contaet metoariarpl

Coat

Crold-tellurium veins wee been Totthd only at the Eng

and on adjoining claims whi: hear

“Cuated on the west jie of md inueh the richest district has been obtained

above Golden Crate, liscovered in At from tliese Properties The

Engineer mines of wekets of quartz worth from &5 to &

Nmelinige at the

) ber por caused considerable excitement during the sUminer of he thid had a decided effect in areusing enthusiasm in quartz ning gold-silver veins ure the most wide spread type of dep. ind

found in a number of localities distributed over th. greater part of the district, ( upriferous silver-gold veins have been found Tab’ mountain, Where, however, only one deposit of any 4

Yromis been 'iscovered. A number of strong.

We'l-mineralized veins, belo;

ing to the silver-lead division, eur on Crater creek and in that

vicinity. Copper veins have been found on the

southern end of Copper island, but those SO far discovered do not

uppear to be !

Present, economic importance, One antimon VeIp ods

ANOWnh ‘ occur in the district; it outerops on the west sl

ore of Taku arm Ww miles below Golden Gate, but as the deposit has been exposed for about 15 feet, very little is known concerning it. Contact-meta morphie deposits, so far as is known, occur only on Hoboe creek near

the upper end of Torres channel. Thess possibly should ell by

sidered as belonging to a single ore body since they are situated along

the same geological contact nd it seems probable that tl between the points where it

leoOre porsists oiterops or has been encountered. The ore-material consists largely of magnetite cartying varying amounts of copper, and wi ver it has been exposed exceeds %0 feet one point 150 feet in thickness. Ont rops have

throughout a distance of at least 3.000 feet,

. and is at

heen discovered

Cott DE poset

Gold-Tellurium Veins

in Atlin d cast side ot

of the veins occur at

of the rich ore in this type of de-

Phyo Partnership

L.G. Nicol

Jornt sto ‘o., Who held believed to have ind partners who held the

resent owners

' t Mines of B t olumbia, for @ach ear, contait the report of the told Commissions of Atlin distriet. in which information is given ¢ erning the development, ete., Pe the wious quartz claims in the distri As these deseriptio: y ronerally vy briet they are not referred in the lists of references h property. ? Robertson, W. F. (Provincial Mineralogist), Report of the Minister of Mines. BC 1900, pp. THO-TH2: 1904, pp. Ge SAG Gwillim, 7. C.. “ Report on the hia,’ Geol neve, Can., Ann. Rep ‘Aa i “Canadian

' ‘

M

Diag. 3. Mineral locations in Atl

ns in Atling

mint

& district, B.C,

Placer Claima are not indie

6 Geological Survey, Canada

Hub A (Diag. 4) is at least 200 feet wide at its widest Point, aie is over 300 feet in length, but owing to a eovering of superficial materials neither the entire length nor width of the vein was ascer tained, The mass consists largely of quartz, but also contains a large proportion of intercalated bands of shale and slate. In places, bands of shale 1 to 2 inches thick alternate with stringers of quartz of similar thickness. At other points the rock has been much breceiated and the particles have been cemented together nainly with quartz and calcite, The relative amounts of secondary minerals and original rock vary greatly, so that in some places there is a predominance of rock, and in others, the vein consists almost entirely of quartz and calcite.

Three veins, A 1, A 2, and A 3, have been definitely traced to a junction with hub A. In addition, A 4, A 5, and A 6 strike toward the hub, and although, owing to superficial covering, they could not be followed to the central arca, their strike indicates that they join it. The strike and form of the quartz of the northern end of hub <A, also

indieate the presence of a wide vein as indicated by A 7, but this ‘s

not exposed.

ATLIN DisTRICT 4h, ©,

rye?

Legend

Lanl

Diag. 4. Map showing the vein out fops on the Engineer min Atlin mining district, B.C.

8S property, and on the Gleaner

amount

reality

of the vein, the

vein

N

N

N

ot

to bevdenes de

intercalated and

n compound vein, It

is exposed to view, but neithe

proportion of roel

eontimives: ta ire reuse, prods i

Al Survey, Canada

Hub B is very similar in appearance to hub A, contains a large

breeciated

shale and slate, ! it least

270 feet wide, !

r wall was found.

and is in

as this much

‘Toward the edges gradually increases, and probably

ug walls of an indefinite charaeter, The following tables give the main characteristics of all the ‘ exeept the two hubs whieh have just been described. Strike Dip Phicktiess. Distance Rernark traced Nous Wosee to NOE 6 to lO teet 300 feet. Comsists tiainky of quartz N. 70° W 0 Apparently 20 to 30 feet, 4000. feet Consixte mainly of quarts nearly ver teal. No IS Wo Nearly cer Average of 350 fret Poward southern end and tical, Wi feet hear the shore, the Vern splits up inte sey uo veins 6 inches to 2 feet in thieknes Vein includes consider able interealated shale, In places up te LO pte of tts welumie s the re mainder of vein mainly quartz HOO W THe to 80% to 2 te 8 feet. 250 feet, Consists mainty of quartz S.E 4 WosO) te NOE. 2to lO inches 800 freer Consists mainly of quartz O49 WF) te 80 tod to BO feet 200 feet Where thin, vein cor ts Ne

matinty of quartz, but in’ thickest portions melndes up to 30) p.e. of intercalated shale layers. Vein toa con siderable extent lies conformable to bedding

planes of formation,

ind so ditfers from: the

majority. of the vear

rT, B,

EEE fesper

Nearly verts

wa for

OO font

feet

Geological Survey, Canada

No. & N13) W. 80® to SW, 10 to 15 feet, 300 feet, Breeciated vein composed almost entirely of broken ind comuninuted pet tions of shate and slate cemented together chief ly by quartz and also te some extent by calcite The proportion of the gangue minerals in the vein varies from pros sibly 75 poe. of 80 pre to lews than 50 p.

No... Apparent 4 1M) feet Strike indicates that it vN. Ow? joins hub B, whieh it Ws much resembles in char acter, being a typical breeciated vein

\pproxtma- 75 feet .. Consists mainly of quartz

tely 4 feet and varying amounts of intercalated shale and altered rock.

All bearings in this report, unless otherwise mentioned, are mag- netic, The magnetic variation in this district is about 33°K,

Mineralization of the Veins.—-The gangue and ore minerals of these veins consist mainly of quartz, ealeite, native gold, one ot more telluride minerals, pyrite, limonite, and native antimony. ‘The majority of the narrower veins are composed almost entirely of quartz with relatively small amounts of calcite; however, as mentioned above, the fissure-filling of No. 7 vein consists predomi- nately of calcite. A number of the veins, particularly the hubs and wider veins, contain in addition to these two gangue minerals, much intercalated and brececiated shale and related materials, and also a greenish chloritic mineral which appears to result from the alter ation of the wall-roecks.

The quartz is characteristically well crystallized, and long delicate prisins are very common; these oceur in parallel! bands with the familiar eomb-structures, or radiate from some central particle or mass of rock or ore. In the inter-erystal spaces, that thus result, the

metallie minerals have largely been deposited. Dense, massive quartz

oecurs in places, mainly in the larger veins, but even there, vugs

lined with quartz erystals are of frequent occurrence, In many

ALLIN Disikit fr, B. Cc,

cuses the Walla of th,

with calcite ervatal Native gold js ¢

and is’in place + phenti

ore, cither ith tithe herp

trite leaves a halt ihe “) ws ‘ a Wi ‘ j if eeeastonal minute and imperfect telluride the principal bas

bably mainly calaverit A few specimens of native

' Uso found. Oeceusional particles of pyrite and

duct, limonite, also occur In seme of the veins

Development Work,—'The original Bngineer ran i Cross-cut tunnel about 300 feet long tap hub A, but Instead of lnterseeting thi CPoss-cut vein AZ, and did not reach the larger deposit feet of drifts and CPoss-cuts Were driven Company also sank a shatt about 20 tect dep on vein point where it comes to the shore of Taku arm; they also sank a compartment shatt that was intended te tap vein Ad, just back the prosent mill; this shaft was tilled with water when visited the writer, but is suid to be about TO feet de Pp. In addition, a few

small surface cuttings were made by this Company,

The Northern Partnership deepened the 20 foot shaft on vein A 4,

but had to cease operations until Winter on aecount of

Two tunnels were commenced on veins No. 5 and No, 7 from the water's edge, and were driven about 10 feet; a tunnel was started on vein No. 1 (Diag. 4), and was run about 30 feet. Vein No. has been followed almost continuously for 600 feet by trenchine from 6 inches to 6 feet deep. A treneh 1 to 7 feet dee p has also been du along the outerop of vein No. 2 for about 200 feet. In addition, few shallow trenches and open-cuts have been made in hub A an hub B, and on veins AS, A 6, B3, No. 3, No. 4, No. 6, and No, 8 This constitutes practically all the development work that has been so far performed on the Engineor mines property. During the past season the work performed by the Northern Partnership was practically all done on the surface, with the object of determining as far as possible the number of yeins and the portions of them that con-

28627 —9

&2 Geological Survey, Canada

tain ore immediately available for milling. This surface prospecting and development was carefully, although necessarily slowly conducted, wid has given very satisfactory result.

A 2 stump Josua THlendry mill, the construetion of whieh was commenced several years ago, Was completed early in the seasen and

Wis in operation during part of the samuner

Values. —Few assays have been made by the Northern Partner ship of the ores on their property; instead, the owners have depended vlinost entirely for guidance in development upon the presence absence of visible gold, with the result that no reliable estimate can be formed as to the probable amount of gold that the hubs and Jarger veins contain. Minute specks of native gold, however, are to be seen in all the larger deposits, and the few assays that have heen made gave resilts ranging im most causes, from traees to about ten dollars per ton. Vers rich ore occurs in poekets or shoots in ao uumber of narrower veins, the best being obtained from veins No. 1, No. 2, Noo 5, No. 7, and Ads in addition, a number of sacks of

good ore Were tuken from No. 3, No. “, A 5, und A 6.

The pockets uppear to oecur inostly at points where the veins are intersected by cross-tissures; they also vary considerably in size, some holding only a portion of a sack while others contain several sucks, The greater part of this pocket-ore has a value of from #1 te #5 per pound. The only body of rich ore of sutticient size to be termed a shoot, that has so far been explored, is in vein No. 1; this has an average thickness of from 1 to 2 feet, is at least 20 te 30 feet in length, measured along the strike of the vein, and has been followed downwards for 3O) feet) without any apparent depreciation in vahues. This shoot might possibly better be deseribed as a portion of the vein in wheh pockets are more common than is usual, but practieally all the material so far obtained from it has been pay-ore

The tirst 800 pounds of selected ore that was milled durin, this past season yielded 20 pounds 5 ounces (Troy) of gold and the next 1,000 pounds gave 20 pounds 8 ounces (Avoirdupois); in addition,

the tailings in each case are claimed to contain approximately 30

percent to 40 percent of the original gold content, but this was not

verified. The ore taken from the various prospecting trenches, open- cuts, short tunnels, ete., during the season up to September 1, was

28627—>p, 82,

STLIN Pete i nic

vaabitend itt ‘te Bree is werkt Hiilliont wy

In aelalit: tte Peiahews (Hartz between the poeliets cts Wi preccbeeeds! pret t tail phied Freetee BTM) fey Morey fer ton Traetion of the ermpaller of thew The etitire feet ‘ ith the

OW Pe ti ares

bare Lieerte cobvt tithe’ Prete

Ser LO feet aed trot

wf F hie

sliwlitty xilizesl, lapels bewuiise izuble timeeale Seepe oeod nal part sHefiaoe, bave been olf, resl tes litneonsite

fi woled-nthver vei of othe il Cemmennon te thee a decided! eppetedy tHleposit. die te the redeetion jas the retioval of a Ptr totbebatitoyst jetty ¢ ate Iphices. fie the wold-tellur HER Werdtis tanned wold te a great extent appears imi arboreseeut forn definitely crystallized ted se intimately inte rer ti ts to feave no doubt as te it Prithary opi purty les hive “ brows tatteeti aud ape al thet] piteBeots

represent an oxidation produet of the ti Trick Phoere

Hoe evidence of any considerable rhice enrichment probah

because the deposits contain ditt Caleite and aliaost no OVER TE those Hck exietoel the Colebpens of the waters int latrtude would very much retard chemical reaetion ing place “tnee the deposits hav been lightiv* altered Paetieals no zone of secondary enrichment 1 groundwater level The veins, therefore. jy eontinie for a conside rable portion if their erty tain almost the simme characteristics and min ralizat surface; with greater depth, however, there js liable +

ines ge in tellurides iitl wo corre ponding decrease in on

ino? ft

o4 GEOLOGICAL SURVEY, CANADA

Origin of the Veins.—-Before the materials composing veins can he deposited, spaces must lave been formed to contain them; a possible exception to this statement, however, exists in the case of veins produced by metasomatie replacement, where the solution of the ori- ginal material and the deposition of the seeondary vein matter are thought to occur simultaneously, In diseussing the origin of the gold-tellurium veins at the Engineer mines,’ the fissures or vein- containing eavities will be first considered and the tissure-fillings or veins will be treated later

The Fissures.—The majority of the fissures, at least, have some- What slickensided walls, showing that faulting has occurred, though, as an examination of the bedded wall-roeks shows, che displacements are generally slight, and often less than one foot. In only a few places has sutticient stripping and development work been done tu enable the relative movement of the walls to be accurately measured, but in none of the cases where this was possible, did the displace- ment appear to be more than 10 feet.

Practically the only other characteristics these fissures possess that appear to assist in the investigation of their origg, are their dips and strikes. The dips are all highly inclined and where not coinciding with, or detinitely intluenced by that of th mtaining rocks, are nearly vertieal. The strikes are the most peculiar and characteristic features of the fissures, in that they radiate outwards

in Various directions from certain central areas, or hubs. The

bedding planes of the containing rocks have naturally greatly

influenced the strikes, the greater number of which are northwesterly as the prevailing strike of th containing formation is N. 60° W. However, a glance at Fig. 2 will show that the fissures have a con- siderable range in strike, and the map of the veins at the Engineer mines (Diag. 4) shows the majority of the fissures radiating from two central hubs. Further investigations and development work may show that the remainitig fissures also join some central quartz area.

A few of the veins, as No. A4, have been deposited to a greater or less extent along the bedding planes of the enclosing clastic rocks, and in these cases the spaces between the strata have been

sufficient to allow the veins to commence forming. ‘This discussion applies also to the gold-tellurium veins on the ad- joining Gleaner and Kirtland groups.

Atlin District, B,C, S5

The forces operative in the earth's erast that eommoniy produces fissuring are those of torsion, tension, and compression, all more or less aided by gravity, Dacbreé! has deme nstrated experimental!

that whenever torsional forces are effective. two systems of fracturing

Fiy. 2. Diagram showing the strikes of the veins at the Engineer mine Atlin mining district, B.C,

tend to be produced, nearly at right angles to each other, Becker”

and Van Hise® have also shown that compressive forces operative

*Daubreé, A., “ Etudes Synthétiques de Géologie Expérimental,” pp.

Becker, Geo. F., ‘‘ Finite homogeneous strains, flow. and rupture of rocks,” Geol. Soc. of Amer., Bull., Vol. IV, 1893, pp. 13-29.

*Van Hise, C. A., Principles of Pre-Cambrian North American Geo- logy, Sixteenth Ann. Rep., Pt. I, U.S. Geol, Surv., pp. 633-682.

86 Geological Survey, Canada

in an approximately homogeneous substance, also give rise normally to two sets of fissures; these occur at about 45° to the direction of the applied force and, therefore, at aboot 90° to each other. Tensional forces tend always to produce a single set of parallel fissures, Fissures forming in the Laberge beds at or in. the vicinity of the Engineer mines, would be greatly influenced by the bedding planes, but still, even taking these into account, none of the forces above enumerated seem to at all adequately account for these radiating ore-containing fissures, so a special explanation is required.

It is evident that if these rocks were subjected to an upward

pressure from below, and this foree were concentrated largely at certain points, that there would be a tendency for fissures to be formed radiating from these points; but as the resisting strength of

w

Fig. 3. Diagram showing the dips of the veins at the Engineer mines, Atlin mining district, B..C.

these beds is much less along their strike than at right angles to this direction, there wou'd be a strong tendency for the fissures to haye northerly strikes. This is what is seen at the Engineer mines, and the fissures there were apparently formed by such localized, upward- pressing forces. Only two probable causes suggest themselves. to account for such phenomena.

The Engineer mines are situated near the eastern edge of the great Coast Range granitic batholith and dykes of related granite- porphyry have invaded the formation there. It is also quite pro- bable that the formation at these mines is wnderlain by great masses of this granitic material; if this is so, it is possible that this

intrusive i. dy may have exerted the upward pressure required ta

ATLIN DISTRICT, B.C, 87 form the fissures under consideration. On the other hand uch an Mitpusive mass if exerting an upward pressure would probably do so not at a very limited number of points each only a few feet in dia meter, but over considerable areas or along certain lines,

An alternative explanation for the origin of the fissures and one which seems more probable will now be given. According to thi- theory, the positions now oeeupied by the hubs were originally weak places in the formation which thus became readily fractured: and ot these points the mineralizing solution~ therefore found easy ace and commenced depositing their quartz and other dissolved materials It has been shown by Becker and Day! that the foree exerted by a erystal while forming, is equal to that required to crush it when con- solidated, and that many fissures have been considerably altere by the growing force of minerals being deposited in them, Accordinets as more and more quartz was deposited and continued te ervstalli/ within these small fractured areas, a great and increasing pressure would be exerted, whieh would naturally find relief in sets of radiat ing fractures such as have been produced at the Enginesr mines, Thi- theory is further strengthened by the fact that the smaller veins eon sist almost entirely of quartz and related vein-materials, but the hubs and larger veins contain a great amount of breeciated and inter ealated rock indicating the friable nature of the rocks there and th: probability of its being much fractured and broken before the deposi- tion of the quartz which consequently formed around and between the fragments. The widths of the hubs are thus probably largels conditioned by that of the friable zone of rocks which had probably heen breeciated by the regional forces that caused the folding aud ti'ting of the formation.

It is also probable that the force exerted by the growth of the quartz, has been an important factor in the formation of a'l the fissures, as once a small opening was produced sufficient for quartz containing solutions te enter and deposit even a small amount of their burden, it is thought that the force of crystallization would be sufficient to gradually force the walls apart to make room for itself and additional solution.

‘ Becker, Geo. F., and Day, Arthur E., ‘ The linear force o growing crystals,” Wash. Acad, of Sci., Proc., Vol. 7, pp. 283-288, 1905.

fH POLGGLOAT SURV ¥, CANADA

Metasomatic replacement has been also a factor here in the production of these veins, but does not appear to have been at ail extensive

The Fissure-tillings.—A study of ore deposits shows, in ger ral,

that they are divisible into the follow ng zones :—

(1.) Oxidized zone. fo {2.) Secondary enrichment zone, ‘ (3.) Upper vein zone, ) (4.) Deepor vein zone,

(5.) Pneumatolytice zone, Primary.

!

(6.) Magmatie zone—ore soliditied

from fusing, J

In any particular deposit, however, one or more of these zones may be missing, or the entire deposit may belong to one zone. During recent years, a number of geologists have studied the various vein- forming minera's with a view to determining their mode of occur- renee and origin, and have discovered that certain mineral com- binations are characteristic of cach of these vein zones.' Also cer- tain individual minerals are diagnostic of particular zones, but us such minerals are prevailingly of rare occurrence, the mineral com- binations are the more useful jn considering the genesis of an ore de posit.

These gold-tellurium ores are only slighty Oxidized, and, as explained previously, are largely at least primary; they are also decidedly not of the magmatic zone; so must belong to divisions 3, f, or 5. Further, none of the minerals are found that are character istic of the deeper vein zone,-such as albite, amphibole, biotite, diop- side, garnet, hornblende, seapolite, spinel, topaz, graphite, ilmenite, pyrrhotite, specularite, ete., and there is a decided lack of the minerals characteristie of pneumatolytic veins, ie, those that are now recognized to be directly connected with plutonie intrusion rocks and have been derived from these through the agency of magmatie gases dissolved in them at the time of their intrusion, and existing therefore, at high pressure and above the critical temperature of

Lindgren, Waldemar, “ The relation of ore-deposition to physical conditions,” Econ. Geol., Vol. IT, No. 2, pp. 105-128.

Emmons, W, H., ‘ A genetic classification of minerals,” Econ. Geol., Vol. HII, No. 7, pp. 611-427,

\ELIN bDisiniey,

Water, Seme of the minerals most Valuable in al

belonging to the pHheumatolytic zone are tourmaline,

spodumene, muscovite, alkali teldspars, cassiterite, wolframite,

molybdenite, magnetite, bornite, and arsenopyrite

It follows by a process of elimination that these gold-tellerium Veins beong to the upper vein zone Moreover the minerals eom posing the deposits are mainly quartz, ealeite, native gold, tellurides, and pyrite. Of these the quartz, pyrite, and native gold are known to frequent deposits of all zones and sv, by themselves, athird little information, The ealeite is alse somewhat persistent, but tellurides are only known in the deeper vein, and upper vein zone It is thus apparent that these deposits belong to the upper vein zone, as they possess a mineral combination characteristic of it, and have none of the peculiarities of the other zones,

That ore-bearing quartz veins are deposited fron cirelating Waters containing dissolved gases and metalliferous eomiy nds, is a now well recognized fact. It is further gi nerally supposed that th Waters are associated with the intrusion of igneous rock. In. the case of these gold-telluriuin veins, granite-porphyry dykes oeenr in the vicinity and the veins are located near the eastern edge of the Coast Range granitic batholith to which the dykes ar’ related. It would thus appear quite probable that the veins are genetieal!s associated with these granitie rocks and that the materials composin:

them were deposited from solutions derived from the granitic magma

THE GLEANER Group.

General.—The Gleaner group consists of three claims and a fraction that lie to the east of and adjoin the Engineer mines (Diag 3). These claims were located jn 1900, and in 1901 the own ors formed a joint stock company, known as the Gleaner Mining and Milling Con vy, who still hold this property. This Company js capitalized f 8250,000, the president is Mr. David Stevens, the secretary-treasirer is Mr. P. F. Scharsehmidt of Whitelor-e. YI and the board of directors include the above named officers and Mr. R. Butler of Atlin, B.C., Dr. Lindsay of Calgary, Mr. D. Yon Cramer of Vancouver, Mr. M. H. McCabe of Victoria, and others.

Robertson, W. F. (Provincial Mineralogist), Report of the Minister of Mines, B.C., 1904, p. G81.

00 Geological Survey, Canada

A wagon-road 4,300 feet long with a good grade was constructed during the past summer from the tunnel en the Gleaner group (Diag. 4) across the Engineer property, to the shore of Taku arm, from which point there is direct steambout connexion with Caribou on the White Pass and Yukon railway, 65 miles distant.

Geological Formations.—The rock formations on the Gleaner claims are the same as at the Engineer mines, ie, they consist mainly of the Jura-Cretaceous shales, slates, greywackes, and tuffs, of the Laberge. series, which have been invaded by occasional dykes of andesite and granite-porphyry, The sediments are in places some what folded, faulted, and distorted, but in a general way have a fairly uniform strike of about N. 60° W. ant dip 30° to 40° to the Hortheast, under the high mountains in that direetion,

The Veins.—The ores on these claims are in quartz veins which ov cur mainly in the dark, finely textured beds of the Laberge series, and four veins at least have been discovered on the property (Diag. 4). No. 1 and No. 2 veins are simple fissure-fillings and consist mainly of quartz, These are exposed on the south bank of Butler creek, strike about N. 20° W., and are from 20 to 30. feet apart. A vein from 3 to 10 inches thick, whica is, in all probability, the extension of either No. 1 or No, 2, outcrops on the north side of Butler creek, where it is broken and offset by a number of faults having dis- placements of from a few inches to several feet each. On the wagon-road about 750 feet from where these veins cross Butler creek, a vein is exposed (marked No. 4, Diag. 4) which is traceable about 100 feet, strikes N. 20° W., is from 1 to 2 feet thick, and is probably also the extension of either No. 1 or No. 2 veins. On the south side of Butler creek about 80 to 100 feet above No, 2 vein, No. 3 vein is exposed and has a thickness of 3 to 4 feet; this is really only a faulted zone in the formation into which has been introduced a considerable amount of quartz which occurs mainly in the form

of narrow stringers and also as a cement uniting the various rock-

fragments. About 700 feet from there in a southerly direction in

the apparent line of strike of No. 3, is a similar zone or compound vein about 10 feet thick, that is apparently the extension of No. 3 and has been traced for at least 400 feet with a general strike about N. 25° W. No. 5 vein is exposed about 100 feet to the south of the

ATLIN DISTRICT, B. ©, Ol

(Gilewner tunnel, is apparently about 2 foot in thickness, and strikes

approximately No 1s? W

Quartz is practically the only ganmgue minerol in. thes veins and with the intercalated lavers and fragments of wall rock, eat stittites nearly the entire veinetilling, with the oxes ption of th small amounts of native gold, iron pyrite, and iron oxide, Whore gold occurs it is generally finely disset inated through the quart it in places, thin leaves and flakes 4 inch across have been teu This mineral has so tar been obtained chietly in poeket~ or shoats which are generally small, but during the latter part of this post summer pocket or shoot was discovered on the north side of Butler ereck that contained several sacks of ore, through all of Whieh

free gold was plentifully visible to the naked eve

Development_—Some small open-euts and trenches have beer made on the veins outeropping along Butler ereek, and a tunnel 10 feet long has also been driven from a point about 1.000 feet te th south of the creek, that was intended to eroe-eut vein No. 3, but

so far this quartz deposit has not been encountered.

THLE SIRTLAND GRoOt Pp,

The Kirtland group is owned by Thos. Kirtland and Captain W. Hawthorn. R.N., and consists of six claims that extend along the vast shore of Taku arm from the Engineer group southward te Loo feet or so across Hale creek, a distance of approximately §,000 feet The geological formation on this property is the same as at the Engineer mines and on the Gleaner group, and the veins that hav: so far been discovered resemble those found on these properties However, on the Kirtland group, only a slight amount of prospecting has as yet been performed and this has practically all been eon tined to the Jersey Lily claim which adjoins the Engineer gro p Several simple quartz veins a few inches in thickness, and ove brecciated vein 2 to 3 feet thick have been diseovere’ Two shafts about 10 and 14 feet deep respectively have bee ak cad a few open-cuts and trenches have been dug.

Since this property adjoins the Engineer mines the torma-

tion is apparently identical on the two properties, it is hoped that

02 herhemele ath SURVEY, CANADA rich ores will also be discovered on the Kirtland group when th claims have leeome more thorought prospected, So far, only 4

slight amount of gold haa been found

Gold-Silver Quartz Veins CENPHAL

The wold-silver quarts veins are the moat widels distributed type of ore deposit in Atlin district, and have been fo nd at a number points, the most important of whieh are: on the White Mooa group and Rupert group on ihe west side of Taku arm above Golden Gate; on the Lawsan group on Bighorn ereek: at the Beavis mine near the town of Atlin; on Munroe and Boulder mountains east of Atlin; and on the Brothon and Alvino chiims on Hoboe creek near the head of Forres channel, an arm oof Atlin lake.

Phese veins oceur in a number of formations including ehloritic and micaceous schists, basie voleanies, and grano diorite, and have Various dips, strikes, ete, but sinee they occur in widely separated parts of Atlin district, some of which were, while others were Hot geolowieully mapped by the writer, sutlicient general informa: tion has not been obtained to determine whether these veins are genetically related or not, or whether they were formed at the same time or produced by the ame agencies, ete, They have been grouped together solely heeause they possess similar mineralogical character- isties

Generally these veins consist cainky of quartz, but some also contain calcite as an associated gangue mineral. Galena and pyrite are the thost common metullie minerals, but in addition chaleopyrite and tetrahedrite frequently oceur, and native gold and native silver are occasionally found, The ores are generally of value mainly for their gold content, but they always contain more or less silver which in places even excocds the gold in value

In most places the veins are only slightly oxidized, and everv- where primary minerals are expo-ed within 5 or 10 feet of the surface, and generally are to be seen in the outerops., The ores are thus for the greater part primary, and contain everywhere mineral

combinations characteristic of the upper vein zone! The veins

different vein zones cre disenssed under ‘ gold-tellurinm ins’

have ale apparent ri ee titiotia whiely ot pe aivitit deri h f Phertee GeitPumve pattie rook reed ine the py rif f there tipenr for tM b Metpety t thie thataape t t the aeanitie rect t the clistriet tithe Weiet rome GHOE TE

lreonera The Whitt Mow MPoup ie sittiated ‘ vent et Taku arm opposite the Engineer mines (Dia and ti emtht claims which wre owned by fous Pereotia, three of whom ue

Dr TES, Young, and Messrs, J. Johnson and Robe Grant. ‘I

Veins, distinguished as the North and South veins re ‘peetively, have heen discovered on this property, Five claims have been located in the valley-bottom along the strike of the North voit, amd tl

extend southward along the shore the length of the tive claims from a point about one-half mile above the mouth of Buchan ereek, The other three claims have been located aloug the South vein which strikes in a northwesterly direction: and the Host eusterty of the claims extends to the shore of Taku arm an wbjoins the most

northerly of those located on the North vein

Geological Formations The rock in th: vieinity of the White Moose group, with the exception of oecasional dykes, all belong to the Mt. Stevens group of lower Pahwosvic age and consist main!y of tinely textured, greenish, sehistose amphibolites that are much

eontorted, faulted, and metamorphosed.

The Veins.—Outerops that an thought to all be portions of the same vein—the North vein-cecur at intervals for a distance of over 5.000 feet, strike in a general direction N. 40° Wy and dip to the northeast at angles ranging from 40° to 60°, Tt is possible, how ever, that these various exposures represent more than on vei, but they all lie in the same general line of strike, dip to the north eust, contain identical mineral combinations, and in every was appear to have a common origin and to be parts of one fissure: filling; so all these vein-portions are here, for convenience in description, at least, considered as belonging to the same vein

This so-called ‘North vein’ varies in thiekness from 18% inchea

to + feet, and consists mainly of quartz whieh is) predominate

wi UROLOGICAL SLEVEY, CANADA

Hiteeive, briaht, aid white ter ecdourke In places elightts stevthep white quart, oewnrs, ane oomuni tial small ported if hite eu'eits vere alee toted. fn wddition to these gamgue mitterals, the vein is faiely well mineralized ehietly with argentifernds totralendpite Fes

' hut walena aticl

eopperh, prymte, ated chalepeypitg opper pe ritey ithtliehite (green Copper stain) aban ceeue At the mest northerly of thie Vent, whee it ce te perge at thee bros + stral fiat

fweone stitile; theme the vein ia about feet thick amd in place ett pret alenicvet entitely of tHetalliferay Hibherals tmeainly tetrahe Heite, chaleopwrite, and galena, with stibortinate pyrite and giataehite Foward the southern end of the claims on this vein. some tren hes vid open-cuts have been made, a shallow Prospect shett h boeverty “unk, and ao erowecut tunnel fas been commenced, whieh has. he ever, net tapped the or vet The vein at the haft ovel in the Vieinity has an average thickness of about @ fewt, eo oabewe the tunnel is 7 fewt thick, but is there net se well minerelived as it Haeces where the thiekness is lew. Et is net known at all detiniteds hew much gold and <ilver the ore in thix ve nh Carries, but wo omdmber ef the assays that have been made wave results of from MLO to @1S in gold and from 20 to 100 ounces of silver per ton

Ihe South vein is from 6 ty LO foet inh thee pees, strikes appr Ni nately N. 57° W., dips to the southwest at angles ranging fren wh te TO, and as composed mainly of querty contaimming Carvine Hnounts of disseminated gala aid chalecepyrite; the metallic constituents were nowhere noted, however, in suthe rent quantities ty cohstitite any considerable pertion of the veinematerial. [Tt ie not

known as vet what this quarts assays

PH) REVERT Got Pp

(reneral.— The Rupert group is owned by Messrs. Allan Rupert and James Johnson and consists of S claims located on the east

face of Whitemoose mountain which is <ituated on the west icle

and near the upper (south) end of Taku arm (Diag. 3 and Phat NXIX), The property is thus on the lakefront. very favourably

situated for mining purposes

Geological Formations.—The general yock formation here is

the same as on the White Moose property and consists of the mem

ee

here

Shieh are lege

pretest. bypciens,

Dexcriptios

eeoup, ate the

f the Mt Stews

shee tele

taf Ves

AVLIN [rs

the wPeeup

tly derbi be tems

He At lew

Howt from a iath

© pp Peontriiately + pe

chiteetl é shore of Tub bieas beet pette teeth towe

Ve in No

about LL 7ier fee

theve afr

ibe rest

rd the ¢

t above

from 2 te feet in

tHeaetited titike on

from 2

Wl steikes pred dips practically puralle

eFulied styl

theinl the

YRie t fe € us

te) huve been eheared ¢ ke

eivl hewh!y egeetane tprlerseed

t ve veces terete cone thee Of his been fot; thee all ip epe

ee leet expersert ote the pce

itt the weet of Hiya et tage crta Che Por comventet: tH cheseription these wt coneecutively, begittting at the Wernt

poof the

aku arr thick tees

vertically, whowe Neo

W., and has a nee

te Sb foet in thiektess, cute Peep

etihtam

1 woterops promiaentiy tio a wuleh at au edevati '

atfikes about No so” W +t

i” No, 2 vein Fie uabeccat heme eer? from to ™ feet its thick iy perpermdlioular attituedl tT

about TO feet aberce

with No, 2 N b sein

ipprosinately G50 feet Cimeasured verti: ) ubowe Ne. 1 lips at High wegles to the southwest, and is from ft to 22 inches in thick hem ein Ne. 4 appears to be ahout 4 feet in thick pe thirt

itiatted approximately 100 feet above Noo t, but it was otbs poted at

one point wad the strike and d p could net be determined ou ae

of the mall extent of (oe. erop Nos

traceable

1, 2,

1, tad & are en

persistent atrike.

ized throm thet voilingly whit vesicular erye! stained reddi

enineral present

(Pher cpeeartz gratigzine

tlso oceur No

and in one place 6 feet of well-mineralized ore occurs

2 vei

uiony the bis f te weve ral

the

httidred feet, huwe facets Wh appear te be similarly mineral t mainky of quartz whieh is pr h ovvasional vies and bunehe f

ted. und it places th iarty

Colona is the prevailing metallic

paringly distributed through rucles of pyrite and native gold vily mineralized than the others

The best spree

mens of native gold are believed to have been found in vein No. 4

On the top of the hill above No. 5 vein, and Iving along ‘s

northern edge of the glacier, are a great number of angular pi

of ore some of

which

are as mnue

h as several hundred pound. in

Ht) Geological Survey, Canada

weight. This ore is different from that of the other veins, so far discovered on the hill, as the meta'li minerals pyrite and galena wre more abundant in it, and frequently exceed in amount the wiungue; also pyrite is there the most abuadant metallic constituent, whereas in the lower veins, pyrite is of somewhat rare occurrence, AN heavily mineralized vein of apparently considerable thickness

Inust, therefore, exist under this glaeior

Values.—-It is not known what amounts of gold or silver these Veins contain, but assays running from #100 to $500 per ton are claimed .to have been obtained; however, it is probable that average tests would give results not exceeding a fraetion of the smaller of these amounts. The information that has been obtained concerning these veins, however, appears te at. least Warrant their further

exploration and development

THE LAWSAN Got P,

General—The Lawsan group is owned by Fred Lawsan, ‘Thos, Kirtland, Wm. Powell, Robt. Pelton. Dan Sullivan, and Agnew A. Lawsan, and consists of six claims located on. the west side of the valley of Bighorn ersek (Plate XXX), ‘This property was first staked in 180s, has since this time been owned by several parties, has lapsed twice, and was located by the present owners in 1909, The greater number of the veins that have been discovered are on the Bighorn claim Where all the development work has been expended. The British Columbia government during the summer of EHO constructed a wagon-road from Kirtland on ‘Taku arm up the valley of Fantail river to Bighorn creek, and thence up the valley of this stream to the lower terminal of the aerial tramway on the Lawsin group, a distance of 10 miles, so this property is now readily accessible,

Geological Formations.—The rock formations on this group and in the vicinity, with the exception of occasional dykes, consist of the members of the Mt, Stevens group, of which the finely textured, greenish, amphibolites predominate, and in these the mineral veins prevailingly oceur, In addition, mieaceous and sericitie schists as well as quartzites occur. Some of the Mt. Stevens rocks are in

places quite fissile, and all are decidedly achistose, and have been

folded, faulted, crumpled, and so metamorphosed that their original

O00 Wid

28627—p, 96

ATLIN DISiKICT, B.C, v7F

character has been masked and in some cases entirely destroyed They have also been invaded by numerous Post-Palwozoie dykes of andesite, rhyolite, and #ranite: porphyry Phe formation in a general way strikes about No 1s Band dips to the northeast ut angles

up te 15

The Veins —— Soins on this property are lens shaped and Li prac tieally twas. cond nable to the foliation Planes of the enelos Ing roek No fissure vey intersecting the forination Were noted lhe lenses are divisib into two groups which were formed ut different — tiny and the older were affeeted x pronounced dyhamie activity before the Hewer Veins came into existence, A l the lenses are quite stnilar in their genera] appourance, and the twa Kroups can only be distinguishes in the field by obser ing the

lutilting,

Che carlier veins are i taore broke than tf fer ots in fact although quartz veins and veins fraginent re onlentifull distributed throughout the formation in this vieinit J and outerops from i fracti moof an men ¢ several foot In Widt re ey whe re

to be seen, vet entire lenses more than a few inches in thie ness ani

5 or 6 feet in length, are ot Fare occurrence, Some lenses are so

faulted that one end only is removed: others qe: irtuiled at both ends; and the original fragments have, in vlaee<. beer ain sub- divided so that a considerable variety of forms pesult One fraement

4 te 5 feet in thickness was noted that bad Jost beth ends, and only a central portion 10) feet long remained Anothey etm with an average thiekneas of s inches oliteropped for GO fost md one end Was complete and terminated in regular lens-fashion, while the other end terminated abp ptly showing that an original portion removed, Many lenses and lens fragments occur up te 200 feet in length and as much as 2 feet in thickness (Fig. 4)

A few lentiewlar veins ocene. however, associated with those Just deseribed, that have bes formed since the greater part of the faulting occurred, and so have been unaffected by theen movements The largest quartz lens noted was from to 4 to 24 Inches jn thickness and over 200 feet in length. This is the vein on which the bulk of the work on the Bighorn ela m Bas been performed

The veins or lenses are omposed of quartz whieh is in place rust-stained and carries small amounts of galena. chaleopyrite

28627 —10

ts GPROLOGICAL SURVEY, CANADA

pyrite, and native gold. Some specimens were seen in whieh parti cles of gold existed, which were as much as tao of an inch in dia

meter. In other places small flakes or leaves of go'd were noted up

Sl

the Bighorn clas

lenses on

ical members of the older quartz

Scale 6ttto tun

a

.] ba & & E

: : e E o ¢

. e jeweut

© é % e ° £ a ® es P

°

a E fa)

Fig

fan inch across. Also from the limited amount of pre- specting and assaving that has been performed it has been fairly

nelusively demonstrated, for the Bighorn elaim at least, that the

Atlin District, Bl ©,

geld occurs in economically Important amounts only in the a veins, and that the older more broken lenses are praetical y barren The owners claim that the 200 foot lens will average 8160 in ell

and silver to the ton —the bulk of this amount being in gold.

Di velopment, Two tunnels 5D und 80) feet long respoetivels have been driven, and some open-euts and trenches have been ash Also a temporary aerial tramway 1,700 feet long has been eon

ttructed to carry the ore from the tunnels down to the vallev-hotterm

Other Claims On Bighiorn Creek,

About 14 miles orth of the Lawsan group, and also on th Western slope of the Bighorn valley at a point ebout opposite Peter's cabin (Diag. 3 and Plate XXX), a fissure-ve oouterops, whieh traccable for a distance of at least 3.000 feet, and throughout this distanee is remarkably persistent in dip, strike, thickness, and mineralization. This vein cuts the sehistose and gneissoid members of the Mt. Stovens wroup oof roeks, has an

thiekness of about 34 feet, strikes N. 56 My and has an almost

, perpendicular attitude, The tissure-tilling consists almost cutirely

of quartz throughout whieh are occasional particles of pyrite. Thi- vein is remarkable for its persistency and for thi faucet that it the only ftissure-vein noted in this locality. The quartz is believed to carry a few dollars per ton in gold, but none of the known assays so far obtained have given more than #10 per ton in gold and silver. At least two claims, the Birdie’ and. the ‘Gold Cup’, owned respectively by Win. Powell and Fred Lawsan, are located ont] vein, and on the Gold Cup two tunnels 35 feet and 1600 feet

length respectively, have been dri on in on the quartz ! 1

The Imperiar Mines!

General. —The Tmperial mines Jones, and di mes Stoke f Atlin, Nanaimo, B.C., and eonsist

the south side of Miners

direction from the town

Robertson, Wo BL. Rey TBS. 759: 1904, pp. G74. GT. Gwillim, J. C., Report bia,’ Geol. Surv., Can., Anr

Osfe7—1 0)

Loo GELOLOGIOAL SURVEY, CANADA

beon constructed ¢ Diag b); the entranee to the bower tiinmel is 10g0 feet in elevation abowe Atlin whos This property was first located in TS), and in 0) was bonded to the Nimrod Syndicate of London. England, whe surveyed and erown-granted the claims, built a tive stump mill and bunk house on the property, and did considerable development, At the end of a year this syndieate abandoned the property and Mr. THerbert Pearce obtained an option on it for 2 years, POR? Sinee this time no work has been performed on the property

Summary, All the work ut the se’ TELE LIOs has been expended it

developing a single quartz lode whieh vecurs ca a tinely-textured roek that ranges from a hornblende-diorite to a hornblende-Jorite porphy- rite. The lode strikes N. 70° E., and dips at angles of 50° to 60 to the southeast. ‘his deposit includes two or three close, parallel, mineralized fissures which contain an aggregate thickness of 2 to 3 feetof Veln material consisting mainly of quartz, sparsely distributed through which are particles of galena, chalcopyrite, pyrite, mala- chite, and occasionally, native gold, A considerable pertion of the

quartz is thought to contain from &LO te &50 per ton jis gold ane

shiver, the silver he Wig ret lativels sthall 11 ghthhotund Two cross-cut tunnels have been driven, whieh tapped the vein at i and 112 feet respectively, and from these over 400 feet of drifts have been driven.

Plenty of water is available at the base of Munroe mountain for crushing and milling requirements, and the falls on Pine creck hearbs, would afford ample power for any ordinars mining require- nents

Phe property thus possesses many natural advantages and con- tains a considerable tonnage of ore which, although low grade, shoubkl

prove profitably workable by modern economical methods. Ceologi-al Formation.—The formation at the Imperial mines

appears to be chiefly a dark greenish to brownish green, dense, tinely textured, rock that is either megascopically entirely apha. .cie or contains Visible hornblende phenoerysts in an aphanitie ground- mass, and ranges from a hornblende-diorite to a hornblende-diorite porphyrite, Under the mieroseope a typical sample proved to be composed largely of plagioclase and pale brownish hornblende, with

-ome aecessory iron ore, the hornblende occurring in shreds and

ATLIN DISTRICT, be, Lol

irregtilor pristiatic forts impertectts terminated and eonustituting

nearly half of the rock mass

Description of Veime All the Work om these tine iat bewete

expended in developing one main vein or lode Which strik tp pret

mately NJ ft dips from 50° to dO" te the outheust, contain here

it tia bean expemed, from bite 7 feet oof vein material, and has been

traced for a distanee of over S00) feet The vein is not simple jn

form but ineludes, ia nmiest places, the quarty atid asscetated mninera

Which have heen deposited in seve ral close paratlel tiesures, and have

also replaced there or less oof the original intervening wallerocd

Phe ven is this a compote Ven, of sition replacement heats teow effective to a considerable degree in altering the intervening: ane intercalated rock-pertions, the term lode is probably most ripper priate On account of its compound mature this vein naturals 7

considerably in thickness, and is alee irregular in. trike and dips The main mineralized fault zone whieh Constitutes this lode is fairly persistent; but the various small ineluded members are quite erratic and in most places the lode is divisible into two or more distinet parts. Tn the upper tunnel on the property a rather typical seetion

gives (-——

It In Hanging wall (Quartz, ete 9 1 Rock somewhat replaced 2 " Fra pe ete Eee “ 7 ack considerably altered and heavily iron stained 1 “ (Quartz ne 0 7 Foot-wall Another section 30 feet to the northeast shows: ht In Hanging wall (iartz, ete ee: oO Kock, heavily iron stained and somewhat de com posed ? 7 ‘uartz, ete 1 1 Foot-wall The vein thaterial appears to have an average iugeregate thiek ness of from 2 to 3 feet and consists mainly of quartz whieh is often

iron stained or rose-coloured, and frequently exhibits Crustifievation

and comb-structures, but is also in places quite massive in appear

anee, Sparsely distributed through the quartz ure particles cdf

fay CRORE CEO AE mERVEYV, CANADA

duleua, chalcopyrite, pyrite, maleehite ind free gold. Pockets or shoots oeeur, however, in whieh thea: metallic minerals oceur plenti fulby

In addition to this main lode, numerous othe r veins and stringers @Xist on the property, and the lower tunnel has cross-cut several festires that contain from 6 te & inches of quartz am! mesoeiated

metallic minerals

Values and Traalment—The ave rage umounts of gold and silver this main lode contains are onty approximately known, but a con siderable portion of the quarts contains probably from #10 ty #0 per ten in these minerals, and asiays have been made that ran aa high as $149 per ton. In 1902 a test sample of this ore weighing 3,207 pounds net, was sent t Pellow-llarvey, Bevant, and Giiman

of Vancouver, B.C., who reported the ore to contain:

Ciold, 1:29 os. valued at 20,00 per coe RIM Silver, 126 o#s, valued ot $20.52 per oz tooose OB BOM sesso exizide - veer beeeKee ss $26

This firm also adds: The beat method of treating this ore

would he first to save the gold by amalgamation on the plates from

rai lower Tunnel. 2 ee ee ee +a oe

' ‘ '

coed

” Gana of horizontal direction Fig. 5. Diagrammatic section through the workings at the Imperial mines, Atlin mining district, B.C. : ey .

a stamp-battery, and then evanide the tailings, when a tota

extraction of about 97 per cent of the gold and silver contents should

a) e saved

ATLIN EtebHICT, B ¢ li

No -ron, comtinued for sever vous the Netived avril cate in 1900 upon the ome et this vein, gave, aecordi: to their

published report, a littl: over @lo per ton in wold

Development As the average lope of the south face of Mune mounwin is about 40°, and the vein dips in the same dir etion, but at an average of approximately 35°, the ore wradually wets farther from the surface of the Hethitain, but cnmtil the foot of the mountain

la (Fig

is Poached the vein ix readily aeeossible by eros eure Cirine J Wo efossscut tunnels have been cbpiven the upper tunnel tapped the vein at a distance of 25 feet and the lower one reached the or itt 112 feet From the ends of these tunnels, drifts have been driven in beth directions, and S80 feet, in all, of unde ryround work has beet

performed

THE Be ANES aeENe.!

Phe Beavis mine is owned by the Gold Group Mining Compan Limited, in whieh Messrs. HL Maluin and Wynn Johnson are the prineipal shareholders, "This property cotisists of nine mineral claitn three of which are eroWhecranted, aid is situated on the east hore of Atlin lake 14 miles north of the Atlin post-ottice (Diag. 5)

Several thousand dollars have been expended in the development of these claims, mainly by two shafts whieh when visited in Ok tober 1910, were tilled with water, so that no detinite information eo tld be obtained concerning their depths or the charaect roof the ore deposit From the material exposed on the dump, the rock in the shafts appears to be maint black chert and chert breecia, but a granite porphyry dyke also cuts the formation in. this vieinits Phe ore apparently consists of a quartz vein, carrying some pyrite aud free

gold.

Bol Lder Mountain: Claims.

General.—A number of cleo. iv been located on the east

slope of Boulder mauutein ‘ Sore ond Baulder creeks, about

12 miles in a northeasterl, dir from Atlin: of these the White

Star Group” (Diag. 3) of three Clavie owned by Captain Wm

' Robertn, W. F.—Report of ‘i Minister of Vf es, BC. 1904. pn. 78d *Robstin W. F. Report of a Min uf “fines, BC.. 1904. p G 76, G77.

ith4 SERVEY, CANAD Ilathorne RN veel phe Luke View gre

re laimes owned be Jf

Wy have beew the tmeowt explored, Other is between ated adjoining these ge if are yl being held, and

is ar tof fireent te ind on the Lake View aml White Seas

ste of therm the an ve outerop that are

ie rties The Proverticm tae thee vious ftom laine cConaiste of the ethers le Mit. Stevens gre f ¢ ss, tainty Che arrephikvolite Cpe tziters. aned tevtie

Gromp—On the White st

#foup tw Veltia eon di Vereud, of tliese, thy or one ’ tis e th tine Stured seliixtose qaophibolite, rem 4 te feet im thick tees trikes No fo W lip to the sentl tat Ohtles fanyong ft “th” to id outerops at an elevation of [ato f et above the lower d “iepe hiake Phin vein COTES t Ee Be ‘ ‘quarty whi ! tinerulized with gulerna, PY Fite, ani total part ‘ ativee probed A tute! Ss feet lore has her riven on the r FoNitnately Bt feet down the meouwnta per from th jie 14 UN ONpesure of quarts aer Whiel tre h oe fee iim he en ug with fo oewemin fer af chee t the diy trike, ete thy hey ieet peer ty The ‘yilar Crebityit oocustonal iptietle ho pax rte ti t NI by t ety found te rr thi netull reittye The Lake Vi i OF Lai ut t ein have also bees vet that at t MP fon ipa thd rine epprosximatels i the direction of the if wrouy Phewe theoueht by ol Vibe? prob th ‘ t® thome four on the Whote Star i r h ' fot vet ‘ pertormed tes justify on The ipitwer t Vie 4 feet shied the lower ernie . t 1) he thi Khe jiuort f beth i Hi tw i i ith ley pyrite, at re speck of mati hd Yt iel ‘ Lith fave nh length has been vo sl i! : 25 eet deep reapeetively have been i nd mytann r ! Hehes and epen-cnut have been dug th Rober Ww Minister of Mines, BC. 1904. iti fiwil 1 Ann. Rep., Geel ., ¢ Vol XPT, 1899, p. 764

NEEES Etta pette 5 i. ¢ lth

@reup of claims, with the pesuie ef the te ithe Clee rence

traced for sewepal by Hiclpeed feet

forneral tatu few einapole haw aot tuttind fy Hethber Mountain feqeesite that assuverd from, 10) te Bhd ME a one oF two ure even clainwal te have given hieher ¢ ' i average f thie Weite w thel piprosabel tert eXeeesd ML and wiit he sspmewhat fe Preis the vortices text that ha tet hiw ver, it te hy feed th f thi eptterty will p fer these when teh eon he ers econo ionthe I) il preerbveed t Hitters other wert will be evereed in thy tit ; the Mountain is it Mest places covered with a manth ipeeet

materiols that hide the bedrock #tel whatever open ie

THE LAVERDIPHE Chot Pp

General Phe Laverdier: Broup ts owned by three beat ore, Messrs, Noel, Frank, and Photos Laverdiore, and itheiat t ‘ claima, three of whieh are crown wranted, and two fractional loin The. Property is sitisaterd cott thee west siefer of Hloboe creek ils t Wiles from where it runs inte Weet bes Which forte the per etd

of Torres channel, an arm of Atlin lake Phe principal ore-bealy the Laverdiere group, or at least the one tiest highly valued ated that on whieh the bulk of the development has ben Spericdert

dese ribed nider eotituet ine tanorphije deposits.’ Ih wlelition ty fissure-veins have been discovered on the Alvine and Brothon respectively, that appear from the limited amount of work that

been performed on them, to belong to the ‘gold-silver quart ein and se will be here deseribed It Is possible, however, that ¢

would be tore appropriatels Classe under high tance silver ve

The Aleine Clarm Phe vem oon the Alvine claim trike approximutely N..d0? W.. haa an average thickness of alae fenet and oceurs in the Coast Range granitic rocks, This dene it tH

f

sists almost entirely of a gangue of quartz whieh is in tuost place

somewhat stained with iron-oxide, and with whieh j ussociated

small amount of white ealeite Disseminated through this wane early everywhere mere or less argentiferous tetrahedrits wee pper containing silver); occasional small particles and flakes of

nat erates ceeur Tt is not known what thie ore will acces

Microcopy Resolution Test Chart

ANSI and ISO TEST CHART No. 2)

— nN @ bd ey

rPrEEcE nN NO

Eee

rrr ‘

——— a —

Mes Mk Was

PPLIED IMAGE Inc

Log GEOLOGICAL SURVEY, CANADA

but its general appearance warrants the expenditure of sutticient work to more thoroughly explore the vein.

The Brothon Claim.—On the Brothon claim, another mineralized fissure cecurs in the Coast Range granitic rocks, strikes N. 25° E., has an almost vertical attitude, and can be traced from near the level of the valley-bottom several hundred feet up the mountain side. In places this fault ine!udes between its walls several inehes of quartz which is associated with some calcite, and contains more or less galena and tetrahedrite, and also occasional particles and flakes of native silver. Near the valley this fissure inc! des only about one- fourth of an inch of decomposed clayey materia! through which, and the somewhat altered and replaced walls for 6 and 14 inches on each side of the fault, is a certain amount of disseminated argentiferous tetrahedrite and native silver. Assays of the mineralized wall-rock have been obtained that gave results as high as 600 ounces and it is claimed that a zone 12 to 14 inches in thickness, bordering the fissure, will average from 20 to 30 ounces of silver per ton.

Cupriferous Silver-Gold Veins. GENERAL.

The veins considered in this report as belonging to the cupri- ferous silver-gold class, have been found in Atlin district only on Table mountain which is situated on the north shore of Graham inlet opposite Taku Landing. The only two deposits on this moun- tain that have been at all developed occur on the Petty and Dundee groups respectively, and occur in granite-porphyry which is intrusive in Chieftain Hill andesites and andesitic tuff’, The veins consist mainly of quartz, calcite, galena, chalcopyrite, pyrite, malachite, and azurite, which minerals occur also to some extent disseminated through the wall rocks. The Petty vein where exposed is from 6 inches to 2 feet in thickness and has been traced for over 100 feet; the Dundee vein has a maximum known thickness of 2) feet, but has not been fo'lowed more than 50 feet.

The Petty Group,

The Petty group is owned by Mr. Tra Petty and consists of two claims which are situated on the southeastern corner of Table moun-

Atlin District, B.C. 107

tain, overlooking Graham inlet. and are about 34 miles in a north. westerly direction from Taku Landing (Diag, 3),

The rock formation in this vieinity consists mainly of the Chieftain Hill voleanies which are bere prevailingly greenish ande- sites and andesitie tutfs. These have been extensively invaded yy dykes of jranite-porphyry, belo. ging to the Klusha intrusives,

Only cone main vein has been so tar exploited on the Potts group, and this cecurs in the granite-porphyry, strikes N, goo E, and has an average dip of about 40° to the northwest. The vein consists mainly of quartz, calcite, galena, chalcopyrite, pyrite, mala- chite, and azurite, and one small cavity was found to be lined With smuali crystals of the rare mineral linarite (a basic sulphate of lead and copper), The quartz is generally rast-stained and occurs associated with varying amounts of caleite which in Peces even exceeds the quartz in amount. Galena and chalcopyr te are the most abundant ore-minerals present, and occur. in approximately equal amounts and in suticient quantity in places to constitute the greater portion of the vein-material, This vein has a thickness, at the widest point so far discovered, of about 2 feet, but rapidly diminishes to 6 inches or less within a distance of 50 feet in each direction, and has not been followed for over 100 feet, It is possible, however, that further development may show the vein to extend 4 somewhat greater distance. In addition, several other mineralized fissures occur in places on both sides of this main fissure, and within distances of 1 to 2 feet from each wall; and the rock between these is to some extent replaced and impregnated with various ore- materials; so that at the main shaft the ore might be considered to have a total thickness of 3 feet at the surface, but towards the bottom of the shaft its thickness is much less. The ore ia claimed to contain four or five dollars per ton in gold, with the main values in silver and copper; but so few tests have been made. that it is uncertain what average amounts of these metals the ore carries.

An inclined shaft 90 feet deep has been sunk on the ore, eom- mencing at the most promising-appearing point on the surface, and within 50 feet an open-cut has also been dug. A trail has been made from the shore up to the wordings, which are about 1,200 feet it elevation above, and directly overlooking Graham inlet.

10s GEOLOGICAL SURVEY, CANADA

Pith DE ND bb Gott pr,

Phe Dundee group is owned by the British Crown Gold and Copper Mining Co, of Victoria, B.C. This Company was incor- porated November 29, 1900, for $1,000,000, with Mr. Seott I, Wallace, of Seattle, Wash,, as Secretary-Treasurer, and Messrs. W. W. lger, F. G. Holder, A. C. Pellissier, and Wm. F. Howe as directors. The property consists of two adjacent claims one of which, the Dundee, adjoins the Petty group to the northeast in the supposed direction of strike of the Petty vein (Diag. 3). The formation on the Dundee xroup is the same as on the Petty claims, and the ore also CUS associated with a granite-porphyry dyke Only one vein has been developed on this property and this strikes N. 30° K., dips to the northwest at 40° to 50°, is lens-shaped, and for 10 or 15 feet has a thickness ranging from 1 to 24) feet. Thirty feet to the northwest from this point of greatest thickness at the surface, the vein is not more than 1 inch thick, and it cannot be traced more than 20 feet to the southwest. It has been supposed that this is the same vein as that on the Petty group, as both strike in the same direction; how- ever, there appears to be no support for this assumption as the vein on the Dundee claim distinctly terminates within 100 feet, at most, of the places where it outcrops, in the direction toward the Petty claims; this is clearly evident from the fact that the rocks are all well exposed in a draw 100 feet from the outerop of the Dundee vein in a direction toward the Petty shaft, and although any vein crossing this draw would readily be seen, none is to be found. Further, if the vein continued from the Petty shaft in the line of strike it ther maintains, it would pass considerably above the showing on the Dundee claims.

The Dundee vein is similar in appearance to that on the Petty group and consists of a quartz and calcite gangue highly impregnated with galena, chalcopyrite, malachite, and azurite. The wall-rock also contains a considerable amount of these minerals disse nated through it. Instead of following a fissure in the central portion of a granite-porphyry intrusive, however, as in the Petty group, the vein continues near the edge of a granite-porphyry dyke, but was nowhere seen to depart from this rock into the adjoining andesitie materials.

Two tunnels having lengths of approximately 20 and 150 feet

et

Atlin District, B.C. 10

respectively, have been driven on the Diitidee claims, but

neither

have cross-cut. the ven; two

tall open-cuts have also been dug A trail has been constructed from the shore of Graham inlet up te the higher of these Workings whieh is about 700 feet abowe and direet

ly overlooking the water

Pk PELTON Ghotp,

The Pelton group is owned by Mr. Ro LL. Pelton, of Taku Landing, and consists of two claims Which adjoin the Dundee group in the direction of the general line of

strike of the vein on this property (Diag. 3). The

rock formations on the Pelton claims are the same as on the Petty and Dundee groups, but no ore has as yet been en countered,

Silver-Lead Veins.

GENERAL, Silver-lead veins are known to occur in Atlin distriet, only on Mt. Leonard, on the north face of which, in the vicinity of Crater creek, are located the main deposits of this class examined by the

writer. When the locality was visited in October, 110, about a dozen claims were held on Crater creek una in the vicinity: of the-e, those on which the most development had been performed, and which have the most promising appearance, belong to the Big Canyon group (Diag. 3), Two smaller veins on adjoining ground ; were also seen. A number of other veins are known to oceur in the vicinity, but owing to the lateness of the season and stormy weather

with considerable snow, these were not examined, The veins seen are all strikingly similar and vary chietly only in size and degree of mineralization The ores all occur in dark-

greenish diabase dykes which have invaded the surrounding granitic

formation, and the general description given below of the deposits

on the Big Canyon group applies to all the veins in the vicinity.

Big Canyon Group?

Summary.—The Big Canyon ¢ roup consists of four claims which were located in 1899 and are owned by Messrs. John Malloy, Thomas

‘ Robertson, W. F., Report of the Minister of Mines of British Col- umbia, 1900, p. 760.

Gwillim, J. C., “ Report on the Atlin mining district, British Colum- bia,” Geol. Surv., Can., Ann. Rep., Vol. XII, 1899, p. 45B.

2

Llu CROLOGIOAL x. RV EY, CANADA

Vaughan, and M. Summers Iwo main veins occur on this pro perty, the lower of which erosses Crate rereek just below the forks of the “treuin, and the Upper Vein Crosses the West bran: h of the crook A short distance above the forks In addition, several smaller veins have been found,

The veing are really mine ralizew diabase ivkex whieh eut the general granitic formation. The ‘pper mineralized dyke, above mentioned, has a width of about 80 feet and is traceable for at least 5.000 feet, and wherever noted is from 8 to 15 fect thiek The lower main ore-bearing dyke is 30 feet thick and is traceable on the surface for several hundred feet. From one-third to one-half of both dykes appear to consist of ore-minerils, chiefly galena, arsenopyrite, pyrite, zine, blende, quartz, taleite, and anukerite These minerals cecur filling fissures and other cavities in the dykes, and also. in place 4, have more or loss replaced the breeeiated dyke material,

The veins contain only small amounts of gold. generally less

than $4 per ton, but are be lieved to contain more important amounts of lead and silver, and are at least deserving of further earefu! exploration and development,

‘eological Formations, The formation on the Big Canyon group consists mainly of a coarsely textured, light coloured, granitic rock Which in many places js porphyritie and contains feldspar pheno- erysts often exceeding an inch in length, This formation has heen extensively invaded by dark-green, tinely-cextured, diabase dykes which are everywhere in evidence The ore deposits occur preyail- ingly entirely within the voleanie intrasives, but in a few places were nod to lie at the contact between these and the granitic

rocks, and in all eases scem to he geneticaily related to the dykes.

Description of the Ve ins.—Two main mineralized dykes or veins veeur on the Big Canyon group; of these, one crosses the right branch of Crater creek possibly 300 or 400 feet above the forks of the stream and the other meets the main ereek a short distance below the forks

Upper Vein.—The upper dyke strik:y . N. 40° E.. dips at 80° to 5 to the northwest, has an average thickness of about 30 feet, and is traceable on the surface for at least several hundred feet. This dvke where *xposed and explored on the left bank of the creek, is roughly

divisible into three parallel bands or zones of about equal thickness,

Pilate Many

Photographs of polished Specimens of ore from the central portion of the 39 feet mi dyke on the Big Canyon group, Atlin mining district, B.C other ore minerals are seen penetrating and re

2662/—p, 110,

neralized The galena, zine blende ankerite, and Dlacina the original dyke mater.al

ATLIN DiaTRicT, Be, tl

The upper zone has been subjected to repeated faulting, and jow eos sista dominantly of brecelated fragments cemerited together tain! with infiltrated quartz, there be tg an inereasing propertion of coment as the central portion of the dyke fs approached. The upper edge of the dyke thus eonsists mainly of reck whieh deerevaes eradually until at a distance of about 10 or 12 feet. there ia a pre dominance of vein materials,

The middle zone of the dyke containa the bulk of the one Which oeeura partly in on or more fis#ure-veing and numerous nar row veinlets, and ales te a vonsiderable extent in irregularly shapont bodies, bunches, ete, which He between or have replaced the breeeia fragments, Metasomatic replacement is here vi ry clearly and vividly ilustrated—rock-fragments occurring in all stages of transition. from those consisting entirely of original dyke materials. to others eam pletely altered to secondary ore- and Veinematter, with the original shapes generally still preserved. Galena and ara hopyrite (arsenieal iron pyrite) are the prevailing ore minerals, but pyrite, zine blends, and ankerite' also oeeur, In addition to these minerals, a certain amount of quartz and ealeite, and more or less altered dyke rock occur constituting the gangue of the ore, In places, however, the ore contains almost no quartz or calcite, and in one of the tunnels in this dyke a body 4 feet in thickness was noted composed almost entirely of galena,

The lowest 10 feet of the dyke has been only slightly alerted: hut lying along the foot-wall is a vein of ore about 1 foot chick composed mainly of galena, arsenopyrite, and altered dyke-rock

Lower Vein.—The lower of the two main ore-containing dykes on

Big Canyon group strikes N, 40° I., dipe at angles 80° te 90

he northwest, is traceable for at least 3,000 feet and possibly

usiderably farther, and is wherever seen from 8 to 13 feet wide This dyke, in a general way. much resem es the upper one jist des- eribed, but is not characterized by distinct zones or persistent bands, and the ore varies in position from place to place, being generally best, however, near the foot-wall. From 4 to 12 feet of this dyvk: is heavily iineralized mainly with galena, zine blende, and arsenc

*CaCO,+ (Mg, Fe, Mn) CO,, or a dolomite in which magnesia is

more or less completely replaced by protoxide of iron or of iron and Inahyanese

Iie CPOE CMTC ATL, MEARVEY, OUN VES

pyrite, but pyrite ae well an ehaheopes rite Couper pyrite) ghee ceaue As in the upper vein the ore oeeurs is fisstires ated tetegilar euvitios Hil ales constitutes irregular bodies, bunehes particles, ete. repehas ing the original dyke rock. In the eavity-fillings considerable quarts atid ealeite coeur, but thee minerals ate almost entirely absent wher thetascmatic processes have heen prevailingly effeetive

Other Veing,-In addition to these twe main bodies, a number of stiall veina, generally a few inches in thickness, were noted, which poms the same geteval ippedaratoe and characteristios that dis

tinguieh the larger deposits

Origin of Deposits —In the Heporits on the Big Canyon wrovup, tm Well us those elaewhere jn the vir inity, both the filling of cavitic ineluding flesures, and the replacement of the original rock have been inetrumental in predueing the ope deposits; but, of the twe processes, replacement appours to have been the more effective

A most striking feature in conPeston with these thepomite is the persisteney with the jaulting sol subsequent mineralization adhere to tho andesitie dykes, In one place a fault, or rather a fuult zone, was followed for over 3.000 feet, anc for thie entine i fanee it remained confined te a dyke that nowhere exeoeds 1 fet in width; and at no peint, as would almost: be expected, does the Tructuring extend inte the gronitie rook om eithes side Phis plete Menon is upparently due to one or both of two eatmes. In the first place, there appear to bea number of old well-defined thes of weak Hess inh the formation in this locality and at the time of the andesitie intrusion the main dykes followed these, and sinee this time the Virtliots stresses to which the earth's crust haa been here subjected have found relief along the same lines. It may also be that the dyke materials are more brittle and less resistant to the forees that have here been aetive than the granitie rocks, and that on this account mainly the fractures have been confined to the dykes. Whatever the wise, it is evident that faulting has been active along these detinite iines for a jong period. commeneing before the andesitie intrusion und continuing possibly to the present time, but at least until long after the bulk of the ore and vein-materials were deposited in the faulted and breeciated dykes, aa more recent veinleta were dis covered cutting portions of the deposits in practically their present

condition

ATLIN Diateter, Be, 1i3

Values The op f ie tt haritee chepieatt tt thee Bie Cativen

gPoup contain only amall ameutte of g Hl, generally fee than #4 per ton. They an believed to carey more important amounts of lead and silver, althe h, however, it io not definitely kpaw? even What average ameitita of theme imetala thers Contain; but troy tiformation obtained? it ja the ht that, altheigh they are dewicdes| low-grnde, these ores a, ertheless, sufficiently extenaive, aid Eokd enough lead, ativer, and wohl to make them worthy of earetaul

exploration and investigation

Development. Ou te Upper vein two tunnels have been driven the lengths of whieh could sot be detern ined of aeeount of jee them, but thes probably have an aggregate longth of over 100 feo On the lower vein a shalt possibly 40 oF 50 feet deep has been sunk and several open-cits and ahallow pite have been dug. Two eroi eut tunnels have boen commenood but have not tapped the ore aa yer, There are in addition a number of opetycuta, trenches, ete, at different points on this property,

Other Deposits,

A dyke crosses Crater creek at a point about 500 feet lower, in attitude, than the outero, of the upper vein of the Big Canyon group, on the right fork of the stream. This dyke strikes N. 27° E., dips from 80° to ° to the southeast, und is about 5 feet in thickness Where it is exposed on the right bank of the creek, about 2 inches of ore occurs on tho hanging-wall of the dyke, and on the left bank of the creek, where the ore is claimed to be considerably thicker, a short tunnel has been driven which when visited had so eaved in that the hanging wall side of the dyke was not visible. The ore seen w is very similar to that in the Big Canyon veins,

At approximately 1,500 feet in an easterly direction from the showings on the B'* Canyon group on Crater creek, another dyke occurs which is al feet in thickness, strikes N. 40 K., and has an almost perpen. iar attitude. This dyke has been subjected to faulting and breeciation until it is new com med almost ent’ ely of rock-fragments more or less cemented with quartz, calcite, galena, arsenopyrite, and zine blende. In places the secondary minerals constitute ebout half of the filling between the granitic walls. A shaft about 10 feet deep has been sunk on this material,

Bi

tid GRLOGIOAL st hVEY, CANADA

Besides these, a np thHher of similar, amd prombeing thepiereite of ore afe beliewed te oeeur fn the Vieimity, but on aeeourt of the lutenesa of the seuein nd the prev sting stormy weather. they wer frast erxathined

Copper Veins.

General. —Copper veina are known to oeeur in Atlin district at only ote point which js sittiated on the southwosters: corner of Copper island’ in Atlin lake (Diag. 3). Several claima were held there for a number of yeara by the Lave riiere brothers, but were

allowed to lapse during the year 1010

fiealogical Formations The rock formation conmaiate of fechlish and greenish, prevailingly coarsely textured, olivine basalta and tuffe; the tuffe however, predominate and in pices Cosist vlimeat entirely of basaltic fragments. but wrade into rocks containing o predominance of sedimentary materials

The reddish basalta range in colour from brownish red te wreenish red, and are distinetly basaltic in habit The groundmass is always eryptocrystalline and contains phenoerysta of olivine and augite at well as particles of iron and oceusionally native copper all of which are readily visible to the unaided eve. In places the groundmass becomes relatively small in amount, eausing the rocks to have a decidedly granular appearance

Under the microscope typical specimens of this reddish basalt proved to be composed largely of basic plagioclase, augite, olivine, and iron oF The feldspars occur in diverse-tabular, lathe-shaped, forms somewhat aitered to saussurite The augite phenocrysts are mainly idiomor phic and qgui'e fresh in appearance, The original olivine individale are dio morphic, but have become almost entirely altered to serpentine, calcite and magnetite, The feldspar, augite, and olivine with their alteration products, also eeeur in the see nd generat, and with the iron ore, econstitute the groundmass which varies in amount from about one-half to one-seveath of the entire rock. Tron ore, with woh in associated par- ticles of native copper, in places constitutes the a eater part of the ground masa,

The greenish basalts are characteristically dark olive-green in eolour, and differ from the reddish varieties, chiefly, in containing

mich less iron, to whieh is due the red coloration.

The Veins.-A number of veins from a fraction of an inch to

6 inches in thickness oecur in fissures in these basaltic rocks, and

Robertson, W. F., Repe- ff the Minister of Mines of British Col umbia, 1964, p. OO

Gwillim, J. C.. “ Kepert on the Atlin mining district, British Colom. bia,” Ann. Rep., Geol. Surv., Can., Vel. XIE, 1899, pp. 689A and 46R

eoteiet tainly ' eabeite, but abe H plaees, cratain pasticles biel Witeees of tative om Pier, the larweet of whlety armewhi te have heen found, ia Fepferte i to have weighed about i forts tebe A certain ate! of Malachite (oon fh green copper stain}, as wall iF particles af eupfite Cred oxide of copper), and tenorite (black oxi of Copper! oceur aa siclat n Products of © Rative copper

Oridin af the ¢ ap pe bhi copper beth in the vette atid adjoining basalts usedottsteadtly fortied of wae deposited in the

ative form aa it how @Xiate, us there jis te ev idence, eHeh ax rein hatte of tittoxidizest sulphides, t heate in any way that this mineral ia a produet of the Nicdized gone The magnetite with whieh the copper is associated i wenerally quite fresh, and the rocks and Vveing are only slightly oxidized except at the very surface: gle: the copper, both on ¢ surface and in the Various elaim workings, is all native exkeopt the slight amount of surface Oxidem chorivod from it In addition, even if there were no other evidence to how that the copper is a prithary mineral here, it is known that throughout thie horthern district where surface Waites ure eold and bet chemically inactive, oxidation Processes pp rodead very slowly and mn ore deposit haa been discovered where pritary tmiterale de pet exist within 10, and wenerally 1 or 2 feet of the surface, Therefore, it ia entirely improbable that on Copper island oxidation would have suceeeded in #o completely altering the original copper minerals both in the veins and adjoining rocks that no traces them now remain. It thus secm# safe to assume that al! + copper in that locality was deposited in the native form,

It remains to determine whether the copper in the As in it primary constituent or has been introduced since their formation As this mineral occurs intimately associated with the iron whieh lecidedly primary to the basalts, it might be supposed that the copper had the same origin. Howey r, the copper both in the veins and walls ia quite the same, and that in the veins in a caleite gangic ie unquestionably secondary to the basalts. Some have suppose! that the vein copper has been leached from the adjoining wall where this mineral js thought to be a primary constituent. If this were the re would be Aa ee reasing amount of copper in the walls as the veine are approached. Tnstead, quite the opposite appears te he the ease, and the copper is much more plentiful ty

aeigt in

116 Geological Survey, Canada

the basalts adjoining veins and other fissures. It, therefore, seems evident that all the copper both in the walls and veins was deposited at the same period and was introduced by uprising solutions, pro- bably deriving their mineral content from the still heated lower portions of the basaltic mogma, and that the great amount of iron cre in the upper cooler portions of the basalts caused the copper to deposit in the native form.

Eeonomic Imporlance.—The copper so far discovered in these veins is not sufticient in amount to be of commercial importance, and although native copper is believed to be distributed to some extent throughout all the reddish basalts on the southwest corner of Copper and adjoining islands, still from the tests so far made it does not appear to oceur in sufficient amount to make these rocks with their inelnded veins profitably workable. It is possible, how- ever, that points may yet be found in this basalt belt, where copper is much more plentiful than at the points so far exploited.

Antimony Veins.

Antimony veins were noted in Atlin district at only one point which is situated on the west shore of Taku arm about 10 miles below (north of) Golden Gate. Two claims, the ‘ Lake Front’ and the ‘ Antimony,’ have been located there by Messrs. James Johnson and C,. B. Dickson (Diag. 3) respectively.

The ore occurs in the form of bedded veins that conform, in a general way, to the stratification planes of the enclosing rocks which lie almost flat and consist mainly of the dark greyish to almost Llack, finely textured, shales of the Jura-Cretaccous, Laberge series.

The main vein is from 3% to 4 feet in thickness and is composed chietly of quartz and stibnite (antimony sulphide) with also some galena, and includes, as well, varying amounts of intereal- ated shale. In some places the entire 3 or 4 feet are com- posed of vein-materials, but in others, beds of shale occur separating the layers of quartz, and constitute about one-half of the material which is, in a general way, regarded as the vein or ore-body. The quartz is generally quite heavily mineralized.

In addition, a number of bedded veinlets ranging in thickness from a fraction of an inch to 2 or 3 inches oceur within 6 feet of

the upper edge of this veir.

Atlin District, B.C. 117

As these ore-muterials occur practically at the water's edge, und lie almost flat, it is not known whether there are other parallel veins below the main deposit or not. The bed-rock is there also nearly everywhere covered with Pleistocene and Reeent superticia! muterials, so that the veins have not been traced more than 10 feet along the surface. Further, a drift about 15 feet in length eon- stitutes the bulk of the development on these veins, so that very

little is really known concerning them,

Contact-Metamorphic Deposits.

General.

Contact-metamorphie deposits of economie interest have been found in Atlin district in only one locality which is situated on Hoboe creck near the upper end of ‘Torres channel, an arm of Atlin lake (Diag. 3).

The valley of Hoboe creek has an average width of about one- half mile, is flat, and contains numerous, swampy meadows which are the result, to a great extent, of beaver dams at different points on the stream. Schists, quartzites, limestones, ete., of the lower Paleozoic (4) Mt. Stevens group apparently underlie a considerable portion of this valley and, for a distance of approximately 2 miles from Torres channel, extend up its western slope as well. Adjoining these rocks on the west are the Coast Range granitic intrusives which constitute the high, steep-sided hills to the west ina south. The contact-metamorphie ore deposits are included in the Mt, Stevens rocks near their contact with the granitic intrusives

Along this contact, the Laverdiere and the Callahan groups of claims have been located (Diag. 3).

The Laverdiere Group,

General.-The Laverdiere group is owned by three brothers, Messrs. Noel, Frank, and Thomas Laverdiere, and consists of six claims, and two fractions. Three of the fractions were located in 1899 and have since been crown-granted. In addition to the contact deposit which is here described, two mineral veins have been discov- ered on this property and are described above under ‘ gold-silver veins.’

Robertson, W. F.— Report of the Minister of Mines of British Col- iumbia, 1904, pp. G79, G 80.

118 Geological Survey, Canada

The main workings on the Laverdiere group are situated on the west- ern edge of the valley of Hoboe creek, 14 to 2 miles from the mouth of the stream.

Ceological Formations, —The Mt, Stevens rocks which outerop along the western edge of the valley consist prevailingly of finely textured, greenish, schistose amphibolites, greenstone schists and limestone. Cutting these and lying to the west and southwest of them are the Coast Range granitic intrusives whieh are prevailingly light grey or pink coarsely textured, granodiorites, The ore pre- vailingly occurs in the older rocks and near their contact with the intrusives,

Description of Deposits. —The ore-deposit is at one point approxi- mately 150 feet in thickness, and wherever a section of the rocks below the granitic intrusives has been seen, at least 30 to 40 feet of ore-material has been found; this consists mainly of magnetite, hematite, chalcopyrite, tetrahedrite (grey copper), malachite, cobalt bloom, and various silicates including considerable yellow garnet, apparently grossulurite, and some biotite. Typical samples of these ores were supplied to Mr. R. A. A. Johnston, Mineralogist, of the Geological Survey, who states: ‘ These specimens consist of an associa- tion of magnetite, chalcopyrite, and oceasional small amounts of tetrahedrite with altered gangue material made up of mixed carbonates and silicates of indefinite composition. The more important minerals in these specimens are sometimes suthiciently well segregated to admit of easy recognition, but in general they are so intimately mixed with each other and with the gangue materials that they can be separated only with very great difficulty; these mixtures are so inti- mate at times as to at first sight present a homogeneous aspect; this intimacy of mixture not only affects the appearances of the different constituent minerals but it also has the effect. of greatly modifying the tarnish colours produced through oxidation: this applies parti- cularly in the case of chaleopyrite which tarnishes to a brownish colour and presents almost the appearance of some pyrrhotite.’

The rock that has been altered and replaced in the formation of the ore-materials appears to have been mainly, if not entirely, the limestone which occurs in bands of varying thickness in the Mt. Stevens series, but in places the limestone has suffered merely

recrystallization and marbleization.

Atlin District, B.C. 119

The best showing is perhaps on the French claim, on which a cross-cut tunnel 158 feet long has been driven of which more than 130 fect is in the ore-body; this assays from 1-65 per cent to 6 per cent copper, and it ia thought that a considerable portion of it will average between 2 per cent and 4 per cent, Numerous faults having displacements of generally only a few inches or a few feet, were encountered in the tunnel, with the result that in some cases blocks of ore were faund adjoining others of rock. The deposit extends up to within a few feet of the granodiorite contact which is about 50 feet in elevation above the valley.

A few hundred feet up the valley from the French tunnel, the contact and its associated ore, by persisting in their southeasterls strike, extend from the hillsides out into the valley-tlat, and are there lost to view, but probably again outerop on the hills to the southeast,

On the Holy Cross claim a tunnel has been driven 35 feet but has not vet been run sufficiently far to reach the main portion of the ore-body. Above the tunnel, however, the ore deposit outerops and is there 40 feet in thickness, and is composed dominantly of granular magnetite, but contains minor amounts of chaleopyrite and malachite as well as erythrite (cobalt bloom) which 1s disseminated through the ore in places and also oceurs coating weathered sur- faces. The ore here, as on the adjoining French claim farther up the valley, extends up the hillside to within a few feet of the contact between the schistose and granitic rocks, which is about 55 feet above the valley bottom. The ore in the Holy Cross tunnel contains less copper than that in the French tunnel and does not, probably, average more than 1 per cent. All the ore on the Laver- diere group is reported to contain small amounts of silver and gold.

Genesis and Age of Deposits.—In studying the eenesis of these deposits a uumber of striking and detinite points have been noted. In the first place, the min-rals constituting the ore-body or ore-bodies are chiefly magnetite, specularite, hematite, chaleopyrite, tetrahedrite, pyrite, yellow garnet, and other complex silicates. This combi nation of hematite and magnetite with sulphides js very character- istie of contact-metamorphie deposits and is practically unknown in fissure veins. Further, when these minerals oceur with Yellow

garnet and related silicates an associatton {is produe:d whieh is

120 Geological Survey, Canada

diagnostic of contact-metamorphism. These same individual minerals may occur in regional-metamorphic ores, but it is highly improbable that a regional-metamorphic deposit should include at one time, and within a few feet, all these minerals which are so characteristic of contact-metamorphic deposits, and no others.

Further, these ore-minerals occur only near tho intrusive grano dicrite contact, and have distinctly Leen produced by replacing the limestones intercalated in the Mt. Stevens series. Plate XXXII shows the ore-materials, largely the garnet and iron-ore, distinetly penetrating and replacing the original rock.

There thus appears to be little or no doubt, but what these ores owe their origin to the neighbouring grano-diorites, ar’ that the miaterials composing them were derived from the grano-diorite magma, as the limestones and adjoining schistose rocks do not con- tain the necessary iron, copper, and su!phur for their production.

As to the cause of contact-metamorphism', petrographers agree that this is due to the heat of the molten magma, combined with the action of water which it contains. In many eases, no perceptible accessions of cabstance from the magma have taken place, while in perhaps as many others, important additions have been received. The amount of material that is derived from the intrusive body appears to be due mainly to two circumstances, the amount of water-gas in the molten igneous body, and the susceptibility of the invaded rock. In many intrusives, there may be present only a very small amount of water-gas, and thus the accession of material to the invaded forma- tion may be slight and the contact phenomena mostly due to the heat of the rock; if, however, the water vapour is abundant, the amount of material given off may be very great. Magmatic waters also vary widely; some contain large amounts of boron, fluorine, chlorine, ete., while others hold none of these, and possess chiefly sulphur, copper, iron, and related minerals. Thus a wonderful variety of contact- metamorphic deposits are tound,

The contact ore-materials on the Laverdiere and Callahan pro- perties are, therefore, in all probability due to magmatic vapours rich in iron, copper, and sulphur, which were derived from the granitic

‘Lindgren, Waldemar, “ The character and genesis of certain con- tact deposits, T.A.I.M.E., Vol. 31.

Barrell, Joseph, ‘ Physical effects of contact-metamorphism,’ Jour. of Sci., Vol. 13.

Amer.

/

euuSvOvONENT NUT OD INS TOn ONT USES vOUEETEDUSONTNS

Plate MAMI,

B. Taken with crossed nicols.

Microphotoyraphs of thin sections of ore from the French claim of the Laverdiere group, on Hoboe creek. Atlin minina district. B.C The dark ora minerals are distinctly seen interpenetrating and replacing the original calcite,

28627 =p. 120.

Atlin District, B, C. 121

intrusive body. If this ia true the deposits were formed during the cooling period of the granitic batholith, which as explained under ‘general geology,’ ia thought to have oeeurred in Jurassic and pro- bably late Jurassic time.

The Callahan Group,

The Callahan group (Diag. 3), owned by Mrs. Callahan, con sists of six claims which adjoin the Laverdiere group on the north and extend in a northerly direction to the upper end of Torres channel, known as West bay. The contact between the Mt. Stevens rocks and the Coast Range intrusives passes through these claims, but is in most places concealed by superficial materials and by forest growth; wherever the contact is exposed, however, ore materials occur in the vicinity much resembling those on the Laverdiere property. These deposits have not been at all developed, the assessment work having been performed on various quartz veins which are generally lens-shap- ed, These occur mainly in greenish schistose rocks and are prevail- ingly only a few inches, but in places are ag much as 6 feet in thick- ness; they show generally only a small amount of pyrite, but ar claimed to contain also native gold.

Coal. General.

No coal in place had been discovered in Atlin mining district to October 1, 1910, but a considerable amount of float and wash coal had been found near the summit of Sloko mountains, at a point to the northeast of and overlooking the lower end of Sloko lake, and a number of claims, generally known as the Sloko Lake claims were located to cover the supposed cos! seams presumed to occur in that locality. The nature vf the detrital coal shows that it has come only a short distance, and Taatalus conglomerate (which wherever found in southern Yukon is associated with coal seams), is exposed immediaiely avove the coal float; it, therefore, appears as if a smal] amount of work should uncover the seams from which the float is derived. As the float and Tantalus conglomerate have been found near the summit of the mountain, the seams when found, unless they can be traced down to lower, more accessible points will not be profitably workable.

123 Grological Survey, Canada

Tantalus conglomerate has been found owhere in Atlin dis trict, and in ail probability coal will yet be found in other places besides in the vicinity of the present Sloko Lake claima.

A seam of coal, 4 feet thick, is reported to oceur on Taku river to the south of Atlin mining district

Sloko Lake Claims,

In 1908 Mr. Alex. MeDonald was informed by Indians of the occurrence of float-coal near the southeastern summit of Sloko mountains, and at a point to the northeast of and overlooking the lower (east) end of Sloko lake. Since then ten claims have been located in the vicinity by Alex. MeDonald, Norman MeLeod, James Johnson, M. A. Dickson, J. Dunham, M. Wynn Johnson, David Gibb, E. Lambert, N. C. Wheeling, and Samuel Johnson, Seven of these claims are now owned or controlled by the Amalgamated Development Co, of Vancouver, B.C,

The rocks outcropping along the shores and on th hills over- looking the lower end of Sloko lake from the north are mainly volcanic flows and tuffs and are prevailingly greyish to yellow in colour except where stained by iron oxide. In composition they appear to be largely midway between rhyolites and andesites, and considerable portions of them might thus be designated us latites or latite tuffs, Occasional basaltic dykes pierce these materials but do not comprise any considerable portion of the general formation, The lava flows or beds lie nearly flat and outcrop horizontally along the walls of Sloko Lake valley, giving rise to benches or terraces forming broad steps up the mountain slopes. These rocks weather and decrepitate rapidly, giving rise to an abundance of talus which in turn decomposes readily to form a fine ash-like material. The mountains are consequently, in most places, rugged and precipitous, and the scenery is wild and imposing.

These voleanic rocks extend to the east down the valley of Sloko river, the outlet of Sloko lake, for approximately 2 miles, where sedimentary rocks belonging to the Jura-Cretaceous Laberge series outcrop and thence continue down the valley for several miles at least. The Laberge beds occur also on the mountain slopes on the north side of Gloko river, where they extend to an elevation of

2.550 feet above Sloko lake at their most northwesterly exposure

nat nenmneunnemaneeer itl saeeieeennenatenenpenanstnnianiidiaenaenend inecsaaeaasiiamanesnieeneeetatoeenadiinenens: neater a

Atlin District, B, 0, 13

about 24 miles in a northeasterly direction from the hortheastern corner of the lake.' There only a narrow tongue of these rocks has been stripped, by erosion and weathering processes, of the original cover of voleanics, and is still surrounded, and overlain ot three sides, by flat-lying beds whieh hide the remaining portions of th. Laberge rocks to the north, east, and west,

The sedimentary beds where exposed strike about N, 70° W dip io the southwest at from 20° to 50°, and consist mainly of dark finely textured shales, sandstones, and #reywackes, and alto include hear the summit of the ridge, some dark conglomerates that belong to the Tantalus conglomerates, and consist entirely of quartz, chert, and slate pebbles, generally tirmly cemented together. All the important coal seams that have been found in northern British Columbia and southern Yukon oeeur in association with these Tantalus conglomerate beds.

The uppermost portion of this sedimentary area just described is, in most places, covered by several feet of weathered and decom. posed material, which is derived from the surrounding and under- lying volcanics and sediments, predominantly from the voleanies, and is in the form of sand, mud, and clay; this in places contains a certain amount of wash-coal which occasionally occurs in layers more or less mixed with other products of erosion and weathering, and near the summit of the ridge, pieces of lignitie coal and earbon- ized wood, as much as 6 inches thick, have been found. Some of the layers of detrital coal were at first thought to be coal seams in place, but they were found on close examination to be float.

When this locality was visited in the latter part of September, 1910, the seams from which the float coal is derived had not been discovered, but it was considered that a small amount of work should expose them. The pieces of coal found are lignitie in character and would make a good fuel, The utilization of this coal, when found in place, will be difficult owing to the fact that it is situated on a mountain-top high above timber-line and in an almost inaccessib'e portion of the district. An attempt should be made to trace the seams, when discovered. te the more accessible

country lying to the east or southeast, in the valleys of Sloko river

*The level of Sloko lake on September 25 was approximately 230 feet above that of the upper end of Atlin lake.

lu4 GROLOGICAL SURVEY, CANADA

or ita tributaries, where it might pay to mine the coal if found in

clean seame of euffleient thickness,

OTHER Coal.

Coal is to be expected wherever the Tantalus conglomerates ceeur, especially where any considerable thickness of the beds rer una. The seuth side of the lower end of Sloko lake and the his along Sloko river are very promising localities and should he carefully proepeected.

Tantalus conglomerates were found on an inconspicuous summit on the south side of Graham inlet about 5 miles southwest of Taku Landing, but only about 30 feet of the beds remains, as the overlying portions have been removed by erosion; however, it is probable that more of the conglomerates occur farther to the south and southwest where the accompanying coal seams should also be found. This probability is very much strengthened by the report that small pieces of coal have been found during the past season

. one of the ereeks running into the north side of Graham inlet

Further, a piece of solid, firm coal, apparently bituminous in character and weighing possibly 20 or 30 pounds, was brought to Atlin by prospectors, and placed on exhibition in the Gold Com missioner’s office. This sample is reported to have been obtained from a 4 foot seam on the Taku river, 12 miles above canoe navi

gation, ad about 30 miles from Juneau,

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Index

A Poe Adamellite, teem aod hy Brégwer a) Alexander, Capt, Jas, assistance of a awtetyed : Alvine claim ... ae Amalgamated Development Co., coal elalae at Sloko lake Ww Snalyaia, Coast Range intrusives BD) ” K'vaeha intrusives , ta Taka group cherta ., S2 Ankerite eons tra ttt Antimony +s ‘ tt, 73, 80, fe claim ., “ 14 veine ., - 4 Are no} trite eens : HHO. 40, 18 sou toulder “Mountain: deposit ‘ 10% Hrothon elaim ore ,. Hawt , Imperial mines ore ay Atlin gold camp, history of... 1,5 ad location and ‘area 8 BR QD soccscasesccecess Ferree ‘i ‘ ve 108, 107, 108

B Besvia mie .. 164 Hibli grapiw .. a Hig ‘ anyon group a Bighorn claim err ; ‘ me, Hiotite - i ° eee 1s Birdie chatin sssesseces a Boulder Mountuin claimea a5 or 1 Beveburn limestones ‘ 6 ; “a british Crown Gold and Copper Mining Ce sy 10" Brothon elaim ... 2500 veeeeee 16 Frown, Edwin, located Engineer mines Kavesecereces vt

Calaverite c.s605. Soereoessces ‘i at Ca ahan SUGED. venntcureat . a Pal Mrs.. owner of Callahan. group , giivete® : 121 Carmack basulte ‘ ci EP 68 Cartme!l, J.. assistance of acknowledged ; : 2 Chaleopyrite ..cccceee oe 92, %, 97, 100, 102, 1086, 107, 108, 112, 118, 119 Chieftain Hill voleanies : paiey Ht Clay, Jow., owner Lake View grou; ‘ Poon a4 Climate Pre ‘ ! GORE cucsacsienvescs bee er re #8, 121, 12s Sloko Lake claims . ae oreyirisie 4 Tantalus eo ' erate . eo . 63, 64, 74, 121, 126 Coast Range intrusives . RiSHAELTES SOR ot enuews siveo bes vy Cobalt bloom ... eeoe ie Saat 18, 119 Contact- metamorphic depo: ts ap SeRRed eERA CE FEERE rer WT Cameet i cesssiverss cs RES Pe i pao ae P 4, 73. 999 - veing .. He Tite- a PPE a ‘ Exevar ees its ba “ eopper in net of commercial importance aieaee Wh Cuprifercus silver-gold veins .. es Tex LeT ES ; 1a DURFUD cccsceccsseses cede Saduececenas eaeeeepne ess fatvskvtesta Ee

Rologicat Survey, © Asada

fhiekeosn, C HK, owner Antimony claim 1 Pratioge Peter Ww Duntee group Las Dunham, J.. asstetatee of aehnow lodged ?

bnginecr mines ,, ; i) ‘

gold-tellarium teins at “

“ : erigin of veine at eee on)

Engineer Mining Co

Fauna and Flora “

Petterty, P. A., assistant in field ae Flora, See Fauna and Flore

Pievmatle , a1, 62.

Praser, J, A., assistance of acknowledged 2

e

Galena . 2, 4, 95, 06, O7, 100, 102, 104, 106, 107, 108, 190,001. 199

Geoloay Big Canyon ‘group 10

Boulder Mountain claims e ‘ ; 104

“ condensed statement of it)

we copper veine tie

. eCOMOMIE ceeeesees eat sh enurde os eeenee ees eeneeene Saat

” @meneral eres oeee : 9,

ed Gleaner claims : ee - sani w

- Imperial mines ‘ve ws er ; 108

y Laverdiere group ee eerenpene er :

Lawaan group . ‘e es tear

be 4 tty group . ‘ ‘ WeKKeass 107

: Rupert group - eke “

“ White FH group , ; we

Oibbina, GO. G., assistant in field a

Gleaner group .. ; ‘ a®

fining and Milling Co , a

field, Beavis mine : ts]

Callahan group ... Py Seer , eov-eersee: Be

Cup claim . , ; ‘ w"

” Engineer mines .. ee ee Seance cee ee MO, SD,

sie (ileaner group aeerves eee re "

Group Mining Co : Sere ae 104

. Imp riaf mimes ees KLERED TERE vs 100, 102

in tiold Cup claim .. ; ‘ an

“in silverlead veins, Big Canyon group 110

- Lake View group 14

Laverdiere group ‘ 119

Lawean group i i 40

placer MINIM cececee oe 8s !

: production of ‘ ; . a

bg rich ores found os revene 12

Rupert group 7 ‘ i,

2 White Moose groop .. e fe Sheer vevee "

“ White Star group ' re ; ' 104

tiold-silver quarts veine ae os Perererrrriyor “FA Ld

Go'd-tellurium weina cece cceees : ; WW 79, ra

Grant, Robt., owner White Moose group rere. . Cy

Gromenlarite oo ...6.ccc cc ees wehat beers Pree errr ys . We

Gwillim, Prof. J. €., ‘yeport on ‘Atlin diatricy seas open PB

; ; H

Ls ReRseNsReors Ciemeetnnee encore: i :hieton encrneeTTteCeee—Esne een ienen-nnete—eeanenmamest te!

encnamanee cameo, setmnentces nes rsemnarsansistes coaeaermenewesunsis ce: (as ake, ata A RR, ee RRR een mame K A) Same! RMN AHS NNR BI OEEHS

ATLIN DIARIO, Be 127 "

Haenwing Vallegs, eaplanation of Ps]

Hawtherne Cape w ewer Houkter Mountain etaine 1a

Kirtland group

Hea ftom @retep at

einatite tte, tte

History 5)

Hlaly Crome 7) 1a

Tetperial mines : an

fiteradnetion ‘ ; !

Iron are in enorme veine ttt

a

Jersey Lily claim : ot

Jolnaon, J, ewner White Moose group : Jas, owner antimony claim 16 ? ps Kupert group

Johnaton, Ro A. A. statement respecting ores of Laverdiere group,, 118

Jones, T. H., owner Imperial mines Hees

a.

Kirtland group . : oe " 7 hos. Owner Kirtland group , at ae Laesan group th)

Klusha iRtrusives or Serve F “?

Laberge eerie. vy be so

Lake Front antimony claim .,.. ’ im”

Lake View group 055., ‘ ; m4

tanning, John, assistant in field .. 4

Laverdiere Bros., copper claims held hy itt

RPOOD cocccoees seve 104, 117

Lawean, Agnew A, owner Laween group a cs Pret. owner Lawsan group . ” i Gold Cup claim .. Ss on - group a¥e ye Reeaey auaness

Limonite énvavdpaveds AO, 81, 89

Linarite

POE POADRECLELDE REY — bKDERRER SS 107 Llewellyn glacier ’ 19, 29 Lode mining : 12 Lowry, R. C., report on Atlin district referred ta ; ? M Magnetite rr - ey OP ESeReS ; 12, 75, 115, 198, 119 Malachite mM, 102, 106, 107. 108," 115,118. 119 Malloy, John, owner, Big Canyon pen de rrr Suan we 109 Marble, handsome and curious atructure RRR EG rea ” Methods of work in field Seeks ben a ; 2 Miller and MeLaren, discoveries by biaceentee cents 5 Monaonite, term adopted by United States Geol Surv. ickioeses ae Moors Wm, A., owner Imperial mines ; eT ee ae ; ) Mt. Leonard, only silver-lead veine on sie a tebe chee Bee c TROVE DOGHO i poe bicsinetendes toukisiccs: as 4a

8 Geological Survey, Canada

Nicol, B. G.. assistance of acknowledged :..0scscrreeenenneeees

Nimrod Syndicate, owners Imperial mines +..++:

Northern Partnership, operations by ..ccccccreeccerreesecevesees owners of Engineer mines

P Pearce, Herbert, option on imperial mines 100 Pelton’ group pee Meee et aL case eeded el AV SESE RUCERERATREST CUES 109 tobt,, owner Lawsan group Was cctetcerivesded beererebecseaaabes 96 “3 R. L., owner Pelton group cesceeceseecceseseseeesunne stece 28 Penhallow, Dr., fossil plants from Tantalus mine examined by . 4 Perking @rOUp oeessscererereeeee cig pia ER Sd GO eaREREVESSERTEESERS 54 Petty gow Eee ee, oye eer ee SEE ies eereehEseceese 106 ra, owner Of Petty Zroup ciccccccecereceeecsreeeeeeeseneeenenes 106 Placer Miming ...ccerscccsccecserrrcee eeeecees 1, 34, 72 Powell, Wm. + owner Birdie claim seceeee . AWSAN QTOUP cessececersreeccers Pyrite ..ccsseee ... 80, 81, 92, 94, 95, 96, 98, 99, 100, 102,

Q Quartz, character of in veins at Engineer minés hite Moose group . Clade cccccccecreccccccceesceses serseneceerveres principal vein filling Gieaner group . ae QuaternAry oo. .cceeceeceseneeeeeees po AkwheRapebbissetiegeseondaaxeneues

Razor Mountain group cecccceee reece settee ee ennennnnnntenereees Rupert, Allan, owner of Rupert group ..

Alvine A rennet “ Brothon claim Imperial mines — Fraverdiere @rOup .cccreceeseeces ceceseeceeeen weanesenes Pomme uate White Moose group

Silver-lead veins e+0%

Table of formations Taku group + ++- Tantelus conglomerate .. as PEAGPEE se pes seecssasseence Tetrahedrite Timber cscccsees Top graphy Transportation facilities sseeeeeeeee Sika lUviceasuenaseeeKees

:

Atlin District, B,C,

Vaughan, Thomas, owner Big Canyon group Veg tation -

w Wieston River volcanics White Moose group - Stur group 3 VelHOW MOGRGE nce ctkcciccasenctasevenss exe bsasue

Younz, Dr. H. S., owner White Moose group...

Zine b'ende ...

SRaey 2

12%)

VPage

al)

os, 1

118, 119

crests@y Ub, 100

. so-so Stet STE eeresssetenee= oo somone aes: 25052

\eaavee reMesnasmenpeRset oes

Canada Department Of Mines

Hox. Lots Coneere, Minister; A, P. Low, Deputy Minisrne ;

GEOLOGICAL SURVEY R. W. Brock, Director

Classified List Of Recent Reports Of Geological Survey.

Since 1910, reports issued by the Geological Survey have been called memoirs and have been numbered Memoir 1, Memoir 2, ete Owing to delays incidental to the publishing of reports and their accompanying maps, not all of the reports have been called memoirs, and the memoirs have not been issued in the order of their assigned numbers, and, therefore, the following list has been vrepared to pre-

vent any misconceptions arising on this account.

Memoirs and Reports Published During 1910

Reports

Report on a geological reconnaissance of the region traversed by th Notional Transeontinental railway between Lake Nipizon and Clay lake iont Ky W. H. Collins No. 1059

Renort on the geslogieal position and ¢ racteristh oft

of Canada By Ry W. ti No. 1107

A reco o nilssanes ro the Macketvte mountains on the Belly, R intl Ciray rivet Yukon and North Weet Territories, By Jareph Keel N 1097

MEMOIRS -iROLnOGTCAT, SERIES

M mow 1. Ne. to Geological Series. Geolowy of the Nipigon Basin, OF turin, Pv Alfred W. G. Wilson

Memoir 2. No, 8, Geological Seric Cieology and ore deposits of Hed ley Mining District. British Columbia, Rw Chartos Cameel!

Mon r 3 No. 3. Geological Serie Palwonisxcid fishes from the Albert Shales of New Brunswieh By Lawrence “tf Lambe

Mem orb New 4 Geatogical Series Pre‘iminary memoir on the Tews and Nerdenskiold Riy Coal district, Yukon ‘Territers

Ry D. DD. Cairne moit 6 No. 5. Geological Series, Geolozy of the Haliburton and Baneroft areas, Provinee of Ontario By Frank D. Adan and Alfred FE. Barlow Memoir 7. No. 6. Geological Seris Geolozv of St. Brune Monuntatr Province of Queher By John A. Dresser

Memoirs “Lopographical Series

Memoir 11. No. 1, Topoaraphical Series Trangniation and spirit: tev ling of Vaneouver I-land, B.C., 1900 By R. H. Chapman

Memoirs and Reports Published During 1911. REPORTS

Report on a traverse through the senthern part of the North West Ter ri ories, from Lav Seul to Cat lake, in 19. By Alfred W. G. Wilson. No

Report on a part of the North West Territories drained by the Winisk and Upper Attowapiskat river-. By W. McInnes. No. 1080

Report on the geology of an area adjoining the east side of Lake Timis-

kat g. By Morley E. Wilson No. 1064.

Memoirs Geological Sertes

Memoir 4. No. 7, Geological Series. Geological reconnaissance along the line of the National Transcontinental railway in) western Quehee. By W. J. Wilson.

Memoir & No. & Geological Series The Edmonton Coal field, Alberta By D. B. Dowling

Memiir 9 No. 9. Geological Series. Bighorn Coal basin, Alberta By G. S. Matloch,

Memoir !'0 No. 10, Geolouical Series An instrumental survey of the

shorelines of the extinet lakes Algonqnin and Nipissing in <onthwestern Ontario By J. W. Goldthwait

AT, netns 4 sameness

uy

NORRDMENETRENRNENESET LIRR Net LFS ssc cone Li recdeas:

Mewwolr Mi tote Memo! Mem

Memo M mor Vemoit Memoir Mi ' ! Me mir Memo r Memoit

Men oit

Is

b

No. 1. Geological Serie Ineeets from the Tertiary lak: depo-ita of the southern interior of Britieh Columbia, e leeted by Mr. Lawrence M. Lambe, tn 1906 iy Anton Haned!irese!

No, 12, Geological Series. On a Trenton Behinoderm Fauna at Kirkfield, Ontario By Frank Springer

No. 12, Geological Series. The elay and shale det ta of

Nova Seotia and portions of New Brunswick By Peis rieh Re ssxiatedt hy Joseph Keele

VEMOTRS BIOLOGICAL SERIES Vv 1. Biological Series New pecies of hella colleeted by

Mr, John Maeoun at Barkley Sound. Vaneouver Island Briti-h Columbia By William FH. Dall and Paul Bartech

Memoirs Published During 1912 MEMOIRS GEOLOGICAL SERIES

No. Wt. Cealogival Serie Southern Vaneouver Island h Charles H. Claon

No. 05. Geological Series The geolory and ore deposits of Phoenix, Boundary Distri British Columbia By ©. 1 LeRoy

No. 16, Geolor Seric Preliminary report on the elag and shale ts of the western provinces By Heinrict

Ries ond Joseph Keele

No 17 Geological Series Report of th Commission appointed to investigate Turtle Mountain, Prank. Alberta

No. 18, Geological Series. The geology of Steeprock lake, O1 tories. Ky Andrew ©. Lawson Notes on fossils from lime stone of Stoeprock Jake, Ontario By Charles D. Walenott

Memoirs Published to Date During 1913.

MEMOIRS GrOLOGICAT SERTES

No. 19, Geological Series. Bathurst district, New Brun-- wick By G A. Young No. 20. Geological Series. Wheaton district, Yukon Terri- tory. By D. D, Cairnes

No. 24. Geological Series. iv and Shale Deposits of the Western Provinces (Part II By Heinrich Ries and Joseph Keele.

No, 22. Geological Series Portions of Atlin district, B.C

By D. D. Cairnes

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Seaie of +

C arady Department of selties

“

he teermre ee By wee

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PRTLIMIN AR) war

4iMiNe POORER TIES

Sv rmbrote

MAP ‘ta

1, Atlin District, B.C

Seaie of mites

by Topography. ul