Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
DSpace
UBCV
Rice, Harington Molesworth Anthony
Master of Applied Science - MASc
University of British Columbia
[Abstract not available]
A SURVEY OF THE GENERAL AND ECONOMIC GEOLOGY OF THE EAST AND SOUTH CONTACT of the WEST KOOTENAY BATHOLITH By Harington Molesworth Anthony Rice A thesis submitted for the degree of MASTER OF APPLIED SCIENCE In the Department of GEOLOGY The University of British Columbia April, 1931. CHAP I INTRODUCTION " 1 TOPOGRAPHY CHAP II 4 5 Regional Local —•--• • ••— • • 5 ,P,HAP III GENERAL GEOLOGY q Subdivisions 9 Northeast of ba tholith 10 Undivided Purcells — — 11 Upper Purcells Dutch Creek (Gateway, Ross ville & Phillips) 13 Mount Nelson — — — — — 14 Windermere series Toby Conglomerate 15 Horsethief & Hamil formations - — 16 Badshot & Lardeap formations 17 Ainsworth series — 20 Point Woodbury, Sarly Bird, Princess, Ainsworth & Josephine 20 Preeambrian intrusives 21 Paleozoic formations — — — — 2 2 Goodsir formation — — 22 Wonah " „ 24 Beaverfoot-Briaco formation — — — — — 25 Mount Forster & Star bird formations 26 Milford formation — — 27 Mesozoio formations Kaslo series Sloean " Pleistocene & Quarternary — — , , 3 2 Cranbrook Section — Lower Purcell series Aldridge formation Creston " Kitchener " Siyeh " Purcell lava - — -Upper Purcell series — Paleozoic formations 28 29 Jefferson limestone 32 33 35 36 37 38 39 40 Wardner formation 41 Ymir section Priest Birer Terrain — — 42 The Summit series — — 45 Irene conglomerate 46 Irene Toleanies — 46 Monk, Wolf & Dewdney formations 48 Bipple formation — 49 Beehive and Lone Star formations — — 50 Pend d 'Oreille series — 60 Bossland group — - — 53 Bearer Mountain group — — — — 53 Bossland seetion Sutherland schist 56 Bossland roleanies and Hall series 57 Mount Bohson formation — 58 Augite porphyrite sills etc — 59 Sophie mountain and Lake mountain conglomerate 61 Boundary seetion Grand Porks schist — — — — — 64 Knot Hill group — — 65 At twood group Brooklyn formation — 67 Bawhide formation — 69 Kettle Birer formation — 69 Midway roleanies — — 70 Summary of the sedimentary geology — 71 <2BAPJLV IGNEOUS GEOLOGY North east of the Nelson hatholith - — — — 75 Nelson pegmatite-gneiss complex 78 Kuskanax hatholith 81 Kootenay Lake Map Area 83 Lardem and Big Bend Map Areas Nelson hatholith 84 Kuska ax bathol it h — — — — — 86 Ainsworth Map Area Gaeissic Phase — 87 Unfoliated granite — 88 Windermere Map Area — — 89 Post Juras sie Lamprophyre Dykes - 90 Cranhrook section Porcell Sills 91 Pur ce 11 lava — 92 Granitic intrusivas 94 Ymir section Granite porphyry tongues — — — — 97 Monzonite chonolith 99 Sunmit stocks 100 Lost Creek and Bunker Hill stocks — — — — — — — 101 Nelson hatholith 102 Bessland section Trail hatholith 103 Diorite porphyrite tongues — — — 104 Andes ite flows — — — 105 Bos sland monzonite — — — — — — — — — — — — 106 Augite latito flows — — — — — — — — — — — — 108 Porphyritle monzonite stocks — — — — — — 109 Sheep Creek diorite porphyrite — — — — — m Salmon Biver monzonite — — — — — — 111 Coryell hatholith 112 Sheppard granite — — — — — — — — 114 Lamprophyre dykes — — — — — — 115 Boundary section Quartz porphyry — — — — — — — — ng Cascade hahholith 117 Nelson hatholith 118 Augite porphyrite — — — — — — 120 Pulaskite porphyry — — — — — — — — — 120 RMAP v ECONOMIC GEOLOGY Windermere Map Area — — — — — — — — 130 Slocan Map Area — — — — — 139 Kootenay Lake Area — — — — — — — — — — — — — — — — — 142 Cr antro ok Area — — — — — — — — — — — — 144 Ymir Area — — — — — — — — — — — — — — — 143 Bossland Area — 1 5 1 Boundary district Phoenix area — — — — 159 Deadwood area — — — — — — — — — 150 CHAP TI GEOLOGICAL HISTORY Northeast of the Nelson hatholith — — 170 Cranbrook section — — — — 177 Ymir section 181 Bossland section — 186 CHAP VII SUMMARY AND CONCLUSIONS Stratigraphieal geology — — — 194 Economic geology — — — 196 Geological History — 198 BIBLIOGRAPHY APPENDIX Table I General Correlation Table — — Table II Analyses of various Igneous Hocks — — — — — — Table III Tabulation of the Order of Geological events in the various sections — — — — — — Graph of various granitic rocks plotted with respect to their conten of Na20, K-jO an& C a 0 Sice toh Map Showing the General Geology of the Area 0 0 0 A S U R V E Y of THE GENERAL & ECONOMIC GEOLOGY OF THE EAST & SOUTH CONTACTS of the W E S T K O O T E N A Y B A T H O L I T H C H A P I INTRODUCTION General Statement The purpose of the following paper is to discuss the general geology of an area that has proved one of the most economically important sections of British Columbia. In it an attempt is made to unify the work of the various officers of the Geological Survey who have worked in different parts of the area since the days of that veteran pioneer G.M.Dawson. With this end in view an effort has been made to work out correlations and a table has been prepared in which they are represented in tabular form. An area that contains a record from the Precambrian times to the present cannot fail to be of interest and it is the hope of the writer that the information collected within the following pages may prove of value in spite of its failure to do justice to an area so full of geological possibilities. As the writer's personal Knowledge is confined to a rapid examination of a number of the mines in the northern I part of the area in 19S6 the information on which this paper is based is derived largely from the publications of the Geological Survey of Canada. The geographic and topographic features have been little mort than touched on, the greater part of the paper being devoted to a description of the stratigraphic, igneous, and economic geology. Following these is a short description of the geological history of the area. Acknowledgements The writer wishes to take tnis opportunity to ex-press his indebtedness to Drs. S.J. Schofield, and T.C. Phemister of the University of British Columbia for the guid-ance and advice so freely given throughout the preparation of this Thesis. Location The area delt with in the following paper lies in southeastern British Columbia, the southern edge of it being along the International Boundary. Geographically, it embraces an area of country en-closed by a line running from Revelstoke southeast to the Columbia river at the head of Windermere lake. South from here it runs down the Columoia river to the International Boundary south of Cranbrook, then along the Boundary to Midway 2 ELY liJ.P ot/i w b]ie location of "he -rep, 2.0 and then hack east again so as to enclose a strip some fifty miles wide, to the Columbia river below Arrow lake, along it and the Kootenay river almost to Kootenay lake. Just before reaching Kootenay lake the line turns north so as to include the strip along the west shore of Kootenay lake known as the Ainsworth Map area. About fifty miles north of the West Arm of Kootenay lake it turns northwest to cut across Slocan lake to the south end of Upper Arrow lake where it turns north again back to Revelstoke. Geologically, the area lies along the east and south contact of the West Kootenay batholith, considering some regions a considerable distance away from it as well as some included in it as roof pendants. Naturally not all the country within the area des-ignated has been discussed, for, on a great deal of it, the information is very scanty. Enough has oeen treated in de-tail, it is considered, to give a fairly comprehensive under-standing of the different types of sediments, intrusives, and mineralization to be met with. 3 C H A P II TOPOGRAPHY Regional The Pacific Cordillera in British Columoia is the result of the work of erosion on the uplifted and folded sed-iments of the two main orogenic revolutions that have been effective in the province. These are the Jurasside revolu-tion during the late Jurassic and the Laramide revolution during the early Tertiary. This Cordillera has a general north-south trend and has been divided into three belts along the main axes of the ranges. They are the Western belt, the Central belt, and the Eastern belt. The first two of these had their inception during the Jurasside revolution when the sediments were ini-tially folded and elevated, the products of their erosion being laia down in the Rocky Mountain geosyncline to the east. The compressive stresses that culminated in the Laramide fatti revolution produced a complex series of folds and thrust^in these sediments and, with the aid of later additional eleva-tion produced the Mountain ranges of the Eastern belt. The older mountains of the Central and Western belts did not suffer much distortion but there must have been a pronounced vertical uplift, probably of an isostatic nature, which re-juvenated the old land and is one of the causes of the mature topography that exists at the present time. 4 Subsequent erosion and particularly the Pleistocene glaciation, has finally carved these ranges into their modern form. The reader is referred to the paper "The Geological Record of the Cordillera in Canada" Traas., Roy., Soc., of Can. 1922 Sec IV pp 79-103 by S.J.Schofield for a complete discussion of a problem that is outside the scope of this paper. Broadly the three belts are represented along the 49th parallel by the following Mountain Systems, 1. The Western belt a. The Insular System, Vancouver Island, etc., b. The Pacific System, the Coast range, £. The Central belt a. The Interior Plateau system, b. The Columbia System. g. The Eastern belt a. The Rocky Mountain System. Local The area being considered lies almost entirely in the southern part of the Columbia Mountain system whose com-ponents are as follows. The Columbia Mountain System 1. The Selkirk range, a. The Purcell mountains, 2. The Monashee Mountains, 5 2. The Cariboo Mountains. Only the first two occur in the area and they oc-cupy the greater part of the district. They are separated by three valleys of major importance each having a north south trend which are as follows:-1. The Rocky Mountain trench; which separates the Rocky Mountains from the Purcell range; the eastern limit of the Columbia system and really a part of the Selkirk range. This remarkable depression can be traced the whole length of M. /¿oo/e*ay the province and is occupied by the Coiumbia^riveriin the area. 2. The second main valley is the Purcell trench. This deep cleft runs from the Boundary north to join the Rocky mountain trench near Golden. It separates the Purcell mount-ains from the Selkirk range proper, whose easterly flank the Purcell range really is. In the area it is occupied by the Kootenay and Duncan lakes and the Kootenay river. S. The last great valley is that occupied by the Columbia river, on its course south, and the Arrow lakes. It serves to separate the Selkirk mounta_ns from the Monashee mountains, the westerly limit of the Columbia system. The local topography is characterized by its mature aspect, and by the general evidence of recent glaciation. Everywhere the igneous and metamorphie rocks rise into jagged peaked mountains from which almost all trace of the original structure has vanished. The peaks are connected to each other 6 oi by the narrow ridges left between the connecting headwalls Sea* the cirque basins and these basins themselves are tre-nsformed to sylvin meadows, often gemmed with emerald lakes about which a profusion of mountain flowers complete a picture of surpass-ing loveliness. Timber line lies between 6,000 and 7,000 feet and below it the topography is more subdued; long, wooded slopes extending down to the agricultural areas occupying the vdley bottoms. Scanned by UBC Library 7 C H A P III GENERAL GEOLOGY Introduction, A long and varied history of sedimentation is writ-ten for us in the stratified rocks of the area. The oldest rook is from late Preeambrian time (Beltian) and from then to the present a record, very fragmentary and imperfect in many points, has come down to us. In no one place is the whole story, even as we have it, preserved in its entirety, but a fragment here and a portion there have been worked out by different men until we have a more or less united whole. Since the area was first studied in 1887 by Dawson many men have worked on the diffarent parts of it, each with his own idea which may or may not have agreed with that of his predecessor or his neighoour. The task of matching the frag-ments into a continuous whole presents vast difficulties and is far from being accomplished. The writer has attempted to correlate the work of different men and to present it in tabulated form in Table 1, appendix. It has been necessary to make many assumptions which may later prove to be unwarrented. It is felt better to have a definite hypothesis from which to work, even if it be wrong in places, than none at all. The impossibility of presenting the record as a whole in the detail it deserves has maae it essential to div-ide the area up into unit districts. These will be tx'eatea 8 at some length and correlations attempted after which a brief summary will be made in an effort to present a more united picture of the area. In pursuence of this idea it will be divided up into the following sections each of which will be treated separa-tely although an attempt will be made to get the relationship of each one to the other. The main hub of the district, as it were, is the vast complex of intrusives known as the Nelson batholith. Round this lie the sedimentary rocks of the various ages, al-though irregular patches are left stranded within the mass of the granite where erosion has not yet proceeded deep enough to remove them. These sediments have been chopped up oy the intrusion of a vast number of igneous bodies subsidiary to the main batholith, rendering the correlation between areas a difficult task, especially since the intense metamorphism that the intrusion of so vast a quantity of igneous matter could not fail to produce, has destroyed all but a few specimens, and these in a wretched state of preservation, of the once abundrnt life. Subdivisions of the Area 1. North east of the Nelson batholith, including the Windermere, Lardeau, Kootenay lake, Ainsworth, Slocan, and Upper Arrow lake Map Areas. 9 2. Cranbrook Section; including the stretch along the International Boundary to the Kootenay river. 3. The Ymir Section; including the area between the Kootenay river and lake to the Columbia river below the Arrow lakes. 4. The Rossland Section; including the area from the Columbia river to Christina lake. 5. The Boundary Section; including the Phoenix and Deadwood Map Areas. 1. THE NORTHEAST OF THE NELSON 3ATH0LITH Introduction; This section covers the whole area east of the Upper Arrow lake to the Columbia river and south so as to include the Upper Half of Kootenay lake. It has been sele-cted as the first one for study as the most recent work in the whole area has been done on this section and the benefits of these up to date opinions may be of service to correct mis-conceptions in the areas tha„ follow. Within this section, too, the least broken strati-graphic succession of formations is found from the base of the Upper Pureells in the Precambrian to the top of the Triassic Slocan series. This forms a valuable nucleous on which to establish later correlations. Wide differentiation in the granite intrusions has oeen worked out by Cairnes but here correlation is almost impossible. 10 Formations of the Precambrian The oldest rocks known in the area are those of the Pureell group. Table»' -'ives a general correlation between the various formations of the Precambrian rocks as they occur in the area. UNDIVIDED PURCELLS OF THE KOOr ENAY LAKE AREA. The Pureell series, as it occurrs to the South of I 2 the Area, has been discussed cy Daly and Schofield at some 1. Daly, R.A. G.S.C. 88 ptl p 119 FTSchofield, S.J. G.S.C. Mem "76 length. The rocks treated in this section,are, however, des-2 cribed by Walker in 1928 and are probably Lower Pureell in 8. Walker J.F. G.S.C. Summ Rpt 1928 p 124A age. Distribution;- They occur only in the South Eastern part of the Kootenay Lake Map Area to the east of Crawford Bay. Petrography:- This series consists largely of grey to green-ish quartzites, grey, black, and buff to reddish schists and some beas of magnesian limestone. The quartzi^&s appear to form the lowest member with the schists, quartzites and lime-stones at the top. The whole series has been nighly metam-orphosed and folded and has a general northerly strike. Age and Correlation:/ These formations were mapped on the 4 West Kootenay Sheet by McConnelland Brock as being underlain 4 7 West Kootenay Sheet, Explanatory Notes, Map 7'9b 11 by lower Swlkirk formations and considered Cambrian in age. 5 Schofield, however, in 1913 and 1914 considered them, as well as the formations previously mapped in the area as the Sushwap, 5T"Schofield S.J. Summ Rpts 1913 and 1914. Niskonlith, Selkirk and Slocan to oe Beltian in age. Later, t£ however, the finding of fossils in the Slocan placed it, most probably, in the Carboniferous. In 1928 Walker was able to 6T~Schofield, S.J. G.S.C. Mem 117. show that the other series, collectively called by Schofield the Ainsworth series were ^recambrian and to correlate them with the series he called Windermere. He also felt them to correspond with the Lower Pureells series of the Cranbrook Map Area. We may, therefor, assume the Lower Pureells to be Beltian in age. THE UPPER PURCELLS Distribution, The formations belonging to this series are divided into two main groups, the Dutch Creek and the Mount Nelson formations."'" 1. Walker J.F. G.S.C. Mem 148 p 7 Members of the first formation are broadly developed in the southern and western part of the Windermere map area and ex-tend from the south end of Windermere Lake to the divide into the Lardeau ana as far north as Horsethief Creek. Rocks of the Mount Nelson formation appear at Mount Nelson and generally 12 form a Northern border to the Dutch Greek formation in the Windermere Map Area, and occur in isolated patches in the £ Dutch Creek formation in the Kootenay Lake Map Area. 2. Walker J.F. G.S.C. Summ Rpt 1926 p 124A THE DUTCH CREEK FORMATION. Walker has correlated this form-ation with the Roosville, Phillips and the upper part of the Gateway to the south. It is the oldest formation exposed in the Windermere Map Area and in the Kootenay Lake Area it over-lies the Lower Pureells. It is composed of a succession of strata varying from slate and quartzite to magnesisn limestone. The slates form the greater part of the formation and vary from grey to almost black or green. They are fine grained and laminated while some are rendered coarser by the presence of a consid-erable amount of sand. The quartzites are thin bedded and fine grained with a faint greenish colour. Where intense folding has deformed impure quartzites$ quartz schists have been formed. The limestones are crystalline^, magnesian and thin bedaed and grey in colour. The limestones rade from east to west into slates ana argillaceous quartzites. It varies in thickness from 1,600 feet to 2,500 feet but the average thickness is nearer the latter figure. Age ana Correlation, The Upper Pureell series of Walker has been correlated by him definitdy to the Pureells of Schofield 2 in the Cranbrook Area and the latter series bote Schofield 3T"§chofield S.J. G.S.C. Musium Bull 2b 1922. and Samson have proved to be Beltian in age. 12 Petrography» As mentioned, the Upper Pureells have been divi-ded into a number of Formations only two of which appear in the area. The Mount Nelson Formation^rests eoniormably on the £ Dutch Creek formation ana consists mainly of limestones and mifelkfer 7TTT U.S.U. Mfem 148 p TU £. Walker J.F. ft.S.fl. Summ Rpt 13SS p 1S4A slates with a band of massive white quartzite at its base and at the top of the section. The lower quartzite is a massive, white granular rock with a siliceous cement. The limestones are grey, blue, white, purple and brick red and are magnesian. They are chiefly fine grained ana crystalline. The slates are grey to black, green and purplish approaching argillites in places. Sun cracks are present in some places indicating sha-llow water conditions. This formation varies in thickness from £,000 feet in the Windermere to 3,400 feet in the Koot-enay Lake Area and is the Youngest known member of the Purcell series. Following the period of uplift and erosion that closed the period of deposition of the Purcell formations came the deposition of the Windermere series. This series has been widely developed all over the area and probably 1 2 corresponds to the Ainsworth series of Schofield. Exact 1. Walker, J.F. G.S.C. Summ Rpt 19E8 p 1*4 2. Schofield, S.J. G.S.C. Mem 117 1920 correlation between the Ainsworth and the Windermere has not, 14 however, been effected and the two series will have to be treated separately. THE WINDERMERE 3ERIES Distribution; Rocks belonging to this series are widely developed to the west of Windermere Lake, and on both sides of Kootenay Lake and extend in a broad band from the head of Kootenay Lake north west to Revelstoke on the main line of the C.N.R. Age and Correlation; The late Precambrian age of the 3 4 Windermere Series has been pointed out by Walker who found 5Tl?alker, J.F. G.S.C. Mem 148 pTT iTWalker, J.F. G.S.C. Summ Rpt 1928 p 125 them to underlie the base of the Camorian uneonformably. It may be assumed, then, that the series is Beltian in age. 5 Bancroft has correlated the Toby Conglomerate with Daly's 5. Daly, R.A. G.S.C. Mem 38 pt 111 sheet 6 Irene Conglomerate at the base of the Summft^ Series. The formations of which it consists are as follows. 6 The Toby Conglomerate 6. Walker, J.F. S.a.C. Mem 148 p 13 Distribution; These conglomerated occur on the divide oetween the Lardeau and the Windermere and at scattered points in the latter Map Area. Petrography; They form a very variable formation 15 ranging from 50 to 2,000 feet in thickness. The matrix is generally slatey with large fragments of slate and occasional boulders of limestone and quartzite bat becomes quite calcar-ious in places and may even become siliceous with large num-bers of quartzite boulders. Walker describes it as a piedmont deposit and suggests fan structure to account for the varia-bility of the thickness. He also suggests that the material may be mainly derived from the eroded Purcells. The Horsethief Formation Distribution; This formation lies along the divide be-tween the Windermere and Lardeau watersheds and to the north-west of Windermere Lake round Horsethief creek from which the formation was named. Lithology; It is about 4,000 to 7,000 feet thick and consists largely of s;rey, green and purple slate with lenses of quartzite and fine conglomerate at the base of the form-ation. Thin beds of blue grey crystalline limestones are com-mon. This is the youngest member of the Windermere series found in the Windermere Map Area. The Hamill Formation 1 Distribution; The Horsethief formation is overlain conformably by the Hamill formation in the Kootenay Lake Map rrtalker J.F. G.S.C. Summ Rpt 1928 p 1251 Area where it is exposed to the east of the Upper half of 2 Kootenay Lake and thence extends up into the Lardeau area in 2. Walker J.F. and Bancroft M.F. G.S.C. Mem f6T 16 in a belt running north west and cutting across the head of Duncan lake. In the Lardeau it is the oldest known formation and forks the Columbia Yalley south of Revelstoke. It also outcrops quite extensively round the head of the Upper Arrow Q Lake. It has been correlated to the Sushwap of Dawson who traced it through from the Sushwap Lake area. 3. Dawson G.M. G.S.C. Annual Rpt 1889 p 298 Lithology; It comprises a succession of strata varying from 7,000 to 10,000 feet thick and consisting of quartzites, schists and limestones. The quartzites form the base of the series and are white to light green and grey and quite massive. Above these is a succession of mica schists, mica phyliites and limestones. The Badshot Formation Distribution; This formation is really little more than 1 an accentuated member of the Hamill formation . It acts as ITWalker J.F. G.S.C. Mem 161 p~T0 such a good horizon marker, however, that a special name has been given to it. It outcrops in a narrow band from the east of the upper half of K-ootenay Lake in a north to northwesterly direction and then on through the Lardeau Map Area in an al-most unbroken line marking the upper termination of the Hamill formation. In the area round the head of the Upper Arrow Lake it occupies a similar relative position. Petrography; The local name "Lime Dyke" has been common-ly applied to the formation since it is composed entirely of a 17 grey, crystalline limestone somewhat siliceous in places. Its 2 thickness ranges from 100 to 250 feet . F7~Walker J.F. G.S.C. Summ Rpt 1928 p 126A The Lardeau Series or Formation Distribution; This series is the youngest in the Wind-g ermere and is also the youngest Precambrian rock known in the 2T"Walker J.F. G.S.C. Mem 161 p 11 area. It is closed by a period of uplift and erosion and on its erosional surface the sediments of the Mesazoic have been laid down. It has been subject to a great deal of metamorphism in many places which has caused a good deal of confusion at times and on account of which Dawson^and others correlated it TTPawson, G.M. G.S.C. Annual Rpi,. id89 p SIB 2 incorrectly with the Sushwap and Nisconlith series . 2. Bancroft, M.F. G.S.C. Summ. Rpt 1?21 p £G7K Petrography. This series consists oi slates, phyllites, schists, quartzites and limestones, all exhibiting a consider-able degree of metamorphism and is from 10,000 to 15,000 feet thick. The lowest members consist of black, carbonaceous slates, phyllites ana schists depending on the degree of met-amorphism. These are succeeded by grey to greenish phyllites and schists. A few bands of limestone occur as a development of the calcarious bands. Precambrian Rocks of the Slocan Map Area Distribution;; Rocks of this age occur in an isolated band at the south end of the Upper Arrow Lake and also in a wider band crossing the Lake about fifteen miles north of Nakusp. Petrography; They are entirely composed of highly met-amorphosed rocks including schists, quartzites, limestones, greenstones and paragneisses. The schists are crystalline, medium to coarse grained rocks with a lustrous appearance. Micas, quartz and feldspar are the main minerals, but meta-crystals of such minerals as staurólote, scapolite and garnet are common giving a knotted appearance to the rock. The quartzites are light coloured, massive well banded rocks with both biotite and garnet commonly developed. The limestones are coarsely crystalline, white rocks with some quartz. Graphite, garnet, diopside and epidote are common secondary minerals. The paragneiss appears to grade into gneissic intru-sives of the Nelson Batholith. Quartz, orthoclase, plagiocla-se, biotites, muscoyite diopside, olivine, apatite, serecite, kaolenite, sphene, graphite and sulphides are all present. The greenstone schist is probably an altered vol-canic rock. Age and Correlation. The extend to which they have been intruded by large batholithic messes of granite has so metam-orphosed them that exact correlation has proved impossible up to the present. Cairnes has, however, referred them to uhe 5T~Uairnes, gTET G.S.U. Summ. Rot. 192b p " T O 19 late Precambrian on lithological evidence while Walker and 4 Bancroft have assumed them to belong in part, to the Lardeau T7"Walker, J.F. & Bancroft, M.F. G.S.C. Mem» 161 p IT formation. Precambrian Rocks of the Amsworth Map Area Distribution; Rocks of the Ainsworth series occur in a band on the west shore of Kootenay Lake in the vicinity of the Town of Ainsworth. Lithology. The Ainsworth series consists of the follow-ing. The Point Wood'oury formation, which is largely made up of micaceous|q.uartzites and garnetiferous mica schists and is the oldest rock known in the area. These strata have been intruded by dykes of gneissic granite and pegmetite and so in-tensely metamorphosed. The formation is some 1,800 feet thick. The Early Bird formation consists of a massive, thick bedded, blue-grey limestone and is 2,300 feet thick. The Princess formation; is predominantly a glittering, mica schist, which is often garnetiferous and interbedded with quartzite, and is 1,200 feet thick. The Ainsworth formation; is largely composed of sandy limest-ones with shaly members in places metamorphosed to hornbien-dite and white marble. It has an average thickness of 600 feet. The Josephine formation; represents the top of Schofield's Ainsworth series. It consists of a collection of strata close on 3,000 feet thick and including dark blackish-green mica 20 hornblend schist, which Sehofield believed to be derived from a water sorted tuff, quartzite, limestones more or less alter-ed and capped by a micaceous, black schistose argillite con-taining knots of staurolite ana andalusite. Age and Correlation. As has been previously mentioned, W a l k e r 1 h a s been able^o show that the Ainsworth series of 1. Walker. J.F. G.S.C. Summ. Rpt 1926 p 124A 2 Sehofield could be considered to correspond with the Winder-ST"Schofield, S . J . G.S.C. Mem 117 p 10 et seq mere. Exact correlation, cannot, however be effected and so the two series have been treated separately. Pre Cambrian Intrusives At the close of Windermere time there appears to have been a considerable intrusion of dykes of varying com-position*" in the Windermere Map area. This phenomina was pro-mfelker, J.F. ft.B.C. Uem U S p £7 bably an accompaniment of the uplift that was taking place at 2 this time. Walker , however, considers it quite probable that ST"Walker, J.F. and Bancroft M.F. G.S.C. Mem 161 some if not all of these intrusives are belonging to the Kaslo series and therefor Triassic in age. They are all highly altered ana vary from an acidic rock, coarsely crystalline and largely composed of opalescent quartz, serecite and some plag-eoclase, chlorite and titanite, to a more basic rock composed largely of chlorite, calsite, and quartz some biotite and pla-geoclase. 21 Formations of the Paleozoic The oldest rocks of the Paleozoic Period are the members l of the Ottertail formation, found in the Windermere Map Area. 1 Walker.. J.P. G.S.C. Mem 146 p~2l The Ottertail formation. Distribution; Rocks belonging to this formation outcrop to the east of Windermere Lake in a band striking northwest and also in an erea some five miles long just north of Horse-thief Greek. Lithology; The formation consists of thick and thin-bead-ed, crystalline magnesian limestones with some sandy members. It is generally grey in colour and varies in thickness from 270 feet to 2,000 feet. Age and Correlation; Walker has correlated this formation, on •i'lithological and stratigrophical evidence, with the Otter-tail of the Field Map Area which Allan , on paleontological evidence, 2 Allan, J.A. G.S.C. Mem 55 p 95 determined to be the v.ry top of the Cambrian or even the transitional zone from the Cambrian to the Ordovician. It lies unconformable* on the top of the Horsethief formation of the Windermere Series but this unconformity is apparently absent in places. The Goodsir formation Distribution; The Goodsir formation lies to the east of 22 the Ottertail as described above and parallels it. The same relationship exists in the area north of Horsethief Greek. Lithology; The formation is very variable in thickness and character in different parts of the area. In the tnickest sections the lower part is generally a succession of calcareous shales and thin-bedded, argillaceous limestones grading upward into thin-bedded, blue-grey limestone. In the thinner sections there is much less limestone and some fine interformational conglomerates. Walker suggests that these conglomerates may have been formed by the disturbance and burial of layers of sun-cracked and calcareous mud. In the Field Map ware a this formation is 6,000 feet thick. Age and Correlation; It overlies the Ottertail conformably and Walker correlates it with the Goodsir formation in the Field Map Area. He also identifies it with the Sabina forma-tion of Sehofield'3 3 Sehofield. S.J. Trans Hoy Can Sec lv 1920 p"76 and the Mons formation of Walcott^ and considers that the name Goodsir, 1 Yfalcott. C.D. Smith. Mis. Coll. Vol 75 Nol takes precedence over them. From fossil evidence it is con-cluded that the Goodsir is Lower Ordovician with its lowest members possibly Upper Cambrian. The Glenogle Shale Distribution; This formation is in three narrow outcrops on the top of the ridge to the east of Windermere Lake. In the Horsethief Creek area of Paleozoic rocks it is absent. Lithology; The lower part of the formation, 1,600 feet in thickness is mainly composed of black slates with inter-bedded mud-rocks and bluish limestones. The upper part is 500 feet thick and composed of sandy shales to thin-bedded, arg-illaceous sandstones. Many fossils especially graptolites have been preserved. Age and correlation; It is considered to be the litho-logioal and stratigraphical equivalent to the Graptolites shales of the Field Map area which were determined to be Or-dovician in age by McConnell^ 2 MoConnell. R.G. G.S.C. annual Rpt 1886 Pt D p 24. Leter collections of fossils have determined the formation to be Lower Ordovician, (Beekmantown). It rests conformably on the underlying Goodsir formation. The Wonah Quartizite Distribution; Occurrences of the Wonah quartizites are scanty and occur to the east of Windermere Lake. Lithology; The rocks comprising this formation consist of relatively pure quartzites and form good horizon markers. In places beds of coarse sandstone are present. The thickness varies from 60 to 170 feet. Age and Correlation; The formation has been correlated to the Halysites beds of McConnel and Allan in the Field Map Area. 24 It overlies the Glenogle shale with a marked disconformity in two oases resting on tae Goodsir. There is little discordance in dip and strike but it is evident that a considerable time gap separates the two formations. Walcott has determined their age to be Upper Ordovician (Lower Richmond). The Beaverfoot-Brisco formation. Distribution; These formations are extensively developed along the range to the east of Windermere Lake and also on both sides of Ilorsethief Creek. Lithology; The Beaverfoot consists of a massive, mag-nesian, crystalling limestone while the Brisco is also lime-stone but somewhat thinner bedded and less magnesian. The change is, however, not at all marked. In fact the transition from the Wonah Q,uartixites through calcarious sandstones is quite gradual. They are at least 750 feet thick. Age and Correlation; They overlie the quartzites of the Wonah formation conformably and have been correlated the upper Halysites beds of McConnel and ¿Han. In the Horsethief area they rest in the Ottertail and Goodsir formations. They were first named and their age determined by Burling-1- who decided that they were Upper Ordovician, 1 Burling, L.P. Geol Mag. Vol L1X 1922 p 454 (Richmond} in age. This applies to the Beaver foot formation. The Brisco formation has been determined by Walcott2 to be Silurian in age. 2 Walcott C.D. Smith. Misc Poll vol 75 Wo 1 p~47 25 It is evident that in the Windermere the Richmond is tran-sitional with the Silurian and no division could be made. As a consequence these two formations have been taken together. The Mount Forster Formation Distribution; This formation occurs only in two small patches one on each side of Horsethief Greek. It has a maximum thickness of 600 feet. Lithology; The strata are chiefly light grey to greenish and pink shales with thin interbeds of a semi-crystalline, fine grained limestone. .age and Correlation; They rest conformably on the Beaver-foot-Brisco strata but the lithological change is very marked and may suggest a considerably time interval during which no sedimentation was going on even if active erosion was absent. Upwards they pass into the Upper Devonian formations so that, in the absence of fossils, it has been called Devonian. The Starbird formation Distribution; This formation occurs only at one locality on the North side of Horsethief Greek and is 2o0 feet tnick. Lithology; The formation is essentially a calcarious one. The rocks grade from limestone at the top through arenaceous limestone to limestone and shale at the base. Age and Correlation; The Starbird formation rests con-formably on the Mount Forster formation and grades into it. The formation has been determined to be Upper Devonian on fossil evidence which is comparatively abundant-'-. It is on 26 this determination that 1 Walker. J.F.""cTG.S. Mem 146 p the age of the underlying Mount Forster is based. At this point there is a break in the stratigraphical re-cord since there is no farther sedimentation in the Windermere until recent times and elsewhere in the Map area the formations listed above do not appear. The Mllford Group •Distribution; This group occurs in a band several miles wide extending from the head of the Upper Arrow Lake where it forms several scattered patches, in a south easterly direction to a little to the west of the head of Kootenay Lake, The pro-jection of this band south is not known. Lithology; The formation consists of shales, argillites and limestones with a basal member of conglomerate which is not everywhere developed. This conglomerate is composed of frag-ments of the underlying Windermere rocks. These fragments app-ear to be poorly classified and to have travelled a relatively short distance. Age and Correlation; The lower members of the Milford group have been identified as Carboniferous-1- and probably Mis-sippian^ 1 Walker. J.F. G.S.C. oumm Rpt 1928 p 127A 2 Walker. J.F. G.S.C. Mem 161 p 12 by a study of their fossils, while Triassic fossils have been found in the Upper members. It has not been determined whether 27 they form a continuous aeries or one with several diseonform-able members. The series overlies several members of the Windermere series with remarkably little angular disconformity considering the fact that such a vast time interval has inter-vened. The Kaslo series Distribution; This group occurs in a band to the west of Kootenay Lake several miles south of Kaslo and runs in a north-westerly direction"*" to a point some six miles North-east of the head of 1 Drysdale. G.W. G.S.G. Summ Rpt 1916 p 56 map Slocan Lake". The band is terminated by a granitic intrusive 2 Cairnes, e.g. G.S.G. Summ Rpt 1928 p 9~4.A Map and is also cut in two by another granite tongue near its nor-therly limit. It overlies the Precambrian rocks unconformably in the Slocan Map -area and the upper members of the Milford group near Kootenay Lake. It also occurs in the form of intru-sivos throughout the Lardeau Map -área where they cut both the Milford and tne Windermere series0. 3 Walker, J.F. & Bancroft M.F. G.S.G. Mem 161 p 14 Lithology; This series is really composed of two members; first a series of greenstones that have been variously called the Kaslo Volcanics4 4 Drysdale G.W. G.S.G. oumm Rpt 1916 p 57 and the Kaslo Schists^ but which Gairnes has grouped in the Kaslo Series. 28 5 Bancroft M.F. Summ Kpt 1919 pt B They are made up of greenstones and chlorite schists which are formed from eruptive fragmentals and are now represented by massive fine grained, green, andesitic schists. Associated with these are a number of greenstone dykes and sills that have been observed cutting both the Windermere and Milford groups. Walker considers it probable that some of the dykes and sills of the Windermere Map Area previously consider-ed to have been Precambrian in age belong to this series. Age and Correlation; The age of the Kaslo series is app-arently arrived at by inference only. It overlies the Triassic top of the Milford Group in the Kootenay Lake area disconfor-mably and is in turn disconformably overlain by the Slocan ser-ies which, according to Cairnes, is probably also Triassic. The Triassic age of the Kaslo series seems to be therefor def-initely established. The Slocan Series Distribution; This series is quite widely represented in all parts of the Map Area except the North-east; it is missing in the Lardeau and Windermere. In the Slocan Map Area it is present in a band trending southeast across the lower half of the Upper Arrow Lake and continuous across to the head of Slo-can Lake. From there a band covers the country for some dis-tance on both sides of the Kaslo-Nakusp railway to within a few miles of Kaslo on Kootenay Lake. From this point it turns south and has been traced by Schofield^ 1 Sohofleld. S.J. G.S.C. Mem 117 paralleling the lake to the West arm. Lithology; It has been divided into two formations in the Ainsworth Map Area by Sohofield; the Silver Hoard formation and the Skyline formation. The former consists of a thick, band of argillites bounded above and below by limestones. The argillites vary from a staurolite schist, hornblende schist, andalusite schist and quartzite to a greenish-brown argillite with well-developed biotite. The limestones are greyish-white, coarsely crystal-line rocks somewhat sandy in places. In some parts it is inter-bedded with thin bands of black argillite. The Skyline formation rests conformably on it and consists mainly of greyish-brown argillite with minor bands of dark blue and greyish-white crystalline limestone. Where these series are cut by the granite the rocks are hard and siliceous but show little contact metamorphic phenomina. Fossils are fairly abundant but are poorly preserved. In the vicinity of Arrow Lake, however, the Slocan series, while still being largely composed of slate, argillite, green-stone and limestone contains also a considerable number of distinctly volcanic members. These have undergone a certain amount of metamorphism with a resulting development of shreds of biotite and muscovite and serecite with metacrystals of andalusite, in the argillite. The volcanic members, however, include at least one augite-andesite lava flow several hundred 30 feet thick at the base of a series of waterlain tuffs and beccias. These tuffs grade into impure, ashy argillites anu are hard to distinguish from them. They are partially recry-stallized and show muscovite, ealcite, epidote and sulphides with bunches of chlorite under tne microscope, as well as crystals of feldspar and mafic minerals. The breccias combine fragments of rock and crystals of feldspar and pyroxene in an ashy ground mass. Age and Correlation; The Slocan series in the region of the Kootenay Lake was considered by both Drysaale and Schofield to be Carboniferous in age on fossil evidence. Cairnes, how-ever, determined them to be Triassic on further fossil evidence in the Slocan ^rea, and, since he has traced the connection through from the Slocan to the Kootenay Lake Area^, we must consider the Slocan series of the latter as being Triassic also seeing that he has done the work more recently. 2 Walker. J.ff. G.S.C. Summ ript 1928 p I'cTI The series lies disconforrnably on the Kaslo group and is the youngest sedimentary rock known in the area. The Pleistocene and Quaternery Glaciation was profound all over the area and resulted in the formation of abundant morainic deposits. These were sub-sequently reworked, forming delta and beach deposits which are common all over the country. Subsequent depressions have left these as much as a thousand feet above any large body of water. This concludes the brief survey of the stratigraphic geology of the north east corner of the batholith. We will next consider the geology of the area further south, the first one to be delt with being the Cranbrook section. 2 m a ciui^iioox oEJTioii This section includes the Cranbrook Map Area and the belt along the International Boundary west of the Kootenay river including the section round Moyie. It lies entirely in the Purcell range of mountains. In this area rocks deposited in the western margin of the Rocky Mountain geosyniciline have been folded to form the Purcell Range of mountains during the Jurassiue revolution-1-. 1 Schofield. S.J. G.S.C. Mem 76 p 19 The rocks include some of the oldest in the entire province which have been ¿.rouped as the Purcell series. This series has been farther subdivided in the Kootenay Lake area by Walker^ into the Undivided lower Purcells and the 2 Walker. J.F. G.S.C. Summ Rpt 1928 Upper Purcells. This division was made so as to place the Dutch Greek and Mount Kelson series in the Upper Purcells. Walker has correlated the lowest formation of the Dutch Greek series with Schofield's Gateway formation. Using Walker's subdivision:— Lower Puroell Series ^ildridge Formation Distribution; The Aldridge formation occurs in three main bodies in the Granbrook Map Area. The central one extends southwest from the town of Cranbrook to Greston on the Crow's Nest branch of the G.P.R. near the Kootenay river. Two other large areas lie one to the north and one to the south of this. Its extension further west is cut off by a large granite stock. It is probable that it is present on the east siae of Kootenay Lake north of this stock although Walker has not been able to make an exact correlation. A band of rocks of lower Purcell age has been mapped by Walker to the east of Crawford Bay and south to Kootenay Lake and it is possible that some member of this may represent the same formation fou$d in the Crenbrook area. Lithology; The formation is made up of a series of ar-gillaceous quartzites, purer ouartzites and argillites. About 33 three-quarters of the series is made up of the argillaceous quartzites which are fine-grained, dark rocks. In thin section they show small, angular interlocking grains of quartz 0.05 to 0.10 mm in diameter, cemented by argillaceous material. Small amounts of feldspar, muscovite, biotite and garnet are also presint. This rock grades both ways into a relatively pure quartzite and to argillites which are relatively rare. It is interesting to note that Schofield suspects the presence of an acidic Pre Beltian Schist in the vicinity of the Selkirk Mountains to the west, from which, in part at least, the quartzitic rocks of the Aldridge formation may have been derived. Metamorphism has not been as pronounced as might be sus-pected by the relative age of the rocks. One exposure of a portion of the argillaceous quartzites where it has been ex-tensively metamorphosed shows the possibilities in this direc-tion. Here the rock has been transformed into a garnetiferous mica schist with the extensive development of muscovite and boitite, and subordinate amounts of garnet, quartz and silli-manite. Schofield concludes, from the fact that sillimanite is a high tempex^ature mineral, that this points to the prox-imity of an intrusive body. He also points out that many of the major ore-deposits occur in this formation. Age and Correlation; Since no fossils have ever been found in the Pux-cell series the division into formations has 34 to be made purely on lithological and stratigraphical grounds. Schofield1 has definitely proved, however, that the whole of 1 Schofield. S.J.. G.S.C.. MissIum~Bull pp 5-15 the Purcell series lies unconformably under the base of the Cambrian. He also shows that the unconformity has little ang-ular discordance and relegates the whole series to the Beltian. The Alaridge formation is the oldest formation exposed in B.C., and is the lowest known formation of the Purcell ser-ies. Its base is, however, nowhere exposed so that it is im-'possible to say on what it may rest. It may, nevertheless, be regarded as fairly early in the Beltian since sufficient time elapsed before the close of the Precambrian to allow for the deposition of at least 33,000 feet of sediments. Schofield has estimated the thickness as about 8,000 feet. The base is, however, not exposed and the top of the formation is so badly folded that Schofield found it impossible to make any accurate observations. The Creston Formation Distribution; This formation, like the Aldridge, is also well developed in the Cranbrook Area. It lies in two bands separating the three exposures of the Aldridge and also to the east of the southern exposure and in a small patch to the west of the northern outcrop. Schofield reports its thickness as 4,500 feet and Daly1 measured a section of it in the 1 Daly. R.A.. G.S.C.. Mem. 38 International Boundary over 8,000 feet thick. 35 Lithology; In general the Creston formation consists of argillaceous quartzites, purer quartzites and argillites, with beds about a foot thick. The quartzites are generally light grey in colour. In this section the rock is observed to be made of very fine grained quartz particles. In other partic-ulars, including the degree of metamorphism, the rooks are very like those of the older formation. The shallow nature of the deposit is well marked in places for ripple-marking and mud-cracking can be seen clearly. Scho-'field notices a progressive decrease in the size of grain going from west to east in this formation. This points strongly to the conclusion that the land mass from which the sediments were derived lay to the west of the basins of sedimentation while the presence of such quantities of sandstone suggests that this land mass can have been at no very great distance. Age ; This series lies conformably over the iildridge formation grading gradually into its uppermost member, there being little lithological difference between the two except that the Greston quartzites are sligntly purer. The Kitchener formation Distribution; Both to the north and to the south of the town of Granbrook rocks of this formation are exposed resting conformably on the Greston formation. Some twenty miles east of Cranbrook an area of Kitchener rocks have been faulted into the Aldridge and Greston formations. These rocks, on their westward extension, phase into the Selkirk series found round »6 Kootenay Lake1. This further establishes the identity of the 1 Schofield. S.J.. G.S.C., Mem 76 p 52 Selkirk with the Pur cell formation as is brought out by Soho-field^ in 1913. Sehofield measured a section carefully on 2 Sohofield. S.J.. G.S.C., Summ Rpt 1915 and 1914 the C.P.R. at Upper Moyie Lake and found it to be 4,500 feet in thiokness. Litnology; The formation consists, in general, of cal-careous and argillaceous quartzites, quartzites and limestones. They phase into the members of the Greston formation below and the Siyeh formation above. Age; The Kitchener formation rests conformably on the Greston but represents a considerable change in conditions. There is a very large increase in the amount of lime present. On the othei* hand the shallow nature of the sea is unchanged since ripple-marking and mud-cracking is still common. Seho-field suspects that the deposit is mainly continental in nat-ure although some marine phases may be present. The giyeh formation Distribution; Rocks of this formation run in a band al-most north and south from Cranbrook to the International Boundary. Another broad band occurs on the Boundary at a point a little to the east of the first band and runs north for some twenty miles. ^ third small exposure occurs right on the boundary to the west of the first band. The approximate thick-ness is 4,000 feet. 37 Lithology; The lower part of the formation is composed of thin-beaded, green, purple and black, mud-cracked metargillitea and sandstones-1-. A bed of conglomerate was seen in one place 1 Schofield. S.J.. G.S.G.. lius Bull. ¿5 j 11 which was succeeded by a chocolate brown sandstone, .about half way up the section siliceous, concretionary, grey limestones occur totalling a thousand feet in thickness. These are suc-ceeded by purple and green metargillitea again which, except for the occurrence of the flows mentioned continue to top of the formation. Age; The Siyeh formation lies conformably upon the Kitchener formation which passes into it without any marked contact. At the top of the formation a number of lava flows known as the Purcell la.Vc.a occur separated by bands of sedi-ments. These sediments are both similar in character to those of the Siyeh formation and markedly different from those of the Gateway which lies directly above. Daly-1- defined the top of the Siyeh formation to.be the base of tne Purcell lava; 1 Daly. R.A.. G.S.G.. Mem ¿8 it now seems necessary to assume that the lava flows extruded during the last part of the Age but that the sediments between them should be related to the Siyeh formation and that the top of it should be taken as the base of the last lava flow. The Purcell Lavas Distribution; These geological bodies occur in the Granbrook area wherever the top of the Siyeh is exposed. 38 Lithology; Daly'J considers these rocks to he basalts and gives a detailed description of them. In association with the 2 Daly. R.A.. G.S.C., Mem 38 pp 207-220 flows he found some sills and dykes cutting the older rocks that he had little difficulty in correlating with the Purcell lavas. These will he treated later under igneous rocks. UPPER PUP.CELL SERIES The Gateway formation Distribution; Rocks, of this formation are exposed in a broad, north-south band lying between the two main exposures of the Siyeh formation. Lithology; The base of the series is a fine grained grit with pebbles of the Purcell lava and quartzite. Above this is a zone of conglomerates and alternating beds of siliceous lime-stones. Beds of dolomite, sandstone and greyish-brown argiil-ite are common. Casts of salt crystals and ripple—marks are common. Age and Correlation; Walker has correlated this upper part of the formation with the Dutch Creek Series described at Kootenay Lake and this forms a link between the formations ex-posed on the north-east corner of the HeIson batholith and those to the east of the Cranbrook Map Area. Schofieid has shown that the Gateway is overlain conformably by the Phillips and Roosville formations further east and that the latter marks 39 the top of the Preeambrian1. These two formations do not 1 Schofield. ¿.J., G.S.C.. Mas. Bull« 55 occur in the district, however, so the top of the Gateway for-mation may be assumed to be the youngest Preeambrian rock in the area. Daly gives the thickness as 2,025 feet. Paleozoic Formations Schofield has recognized two groups of this Era 1 Schofield. S.J.. G.S.C.. Mem 76 p 5o one Devonian and one Carboniferous. He has grouped the.m toge-ther on the map as it proved impractical to attempt to treat them separately. Distribution; The area underlain by these rocks lies to the south-east of Granbrook along the west side of the Koot-enay river. The Jefferson Limestone Schofield measured 150 feet of this formation but neither the top nor the bottom was exposed. Litholojgy; These rocks are mainly massive to thin-beaded siliceous limestones some members of which are very sandy. Age and Correlation; The Jefferson formation rests with no discordance of strike or dip on the members of the Gateway, Purcell lava and the Siyeh formations which shows the remark-able passive nature of the uplift that closed the Preeambrian. The evidence of disconformity is commonly present, however. 40 The age has been determined as being Devonian. It was suggest-ed by Dr. Kindle that they might be the equivalent of the Jefferson limestone of Montana and for this reason Schofield tentatively adopted that name for the formation. It is very probable that the formation may be the equivalent of the Star-bird formation of the Windermere. Atrypa reticularis and Schiiophoria striatula1 are common to both formations. 1 Walker. J.F.. G.S.G., Mem 148 p 55 The Wardner formation Schofield roughly estimates the thickness of this form-ation to be 1,000 feet. Lithology; The Wardner formation consists almost entire-ly of grey, thin-bedded limestones some beds of which contain chert nodules. Age and Correlation; The contact was not clearly seen but the Wardner formation is believed to overlie the Jefferson formation conformably. Examination of a fossil collection seemed to indicate the Mississippian age of these limestones. They may be the equivalent in part, of the Milford Group but no direct evidence is forthcoming. These beds are overlain by the unconsilidated sands and gravels of the Pleistocene. 41 Ymir Section The next area to be considered is that lying 600U bourn/-between the Kootenay river and thc^ Columbia river and south of the West Arm of Kootenay lake; an area lying in the Selkirk Mountains. The most recent work in the vicinity has been done in the Ymir Map Area. The Priest River Terrane Series Distribution; The oldest rocks in the area were studied by Daly1 in 1911, who found outcrops of highly metamorphosed and altered 1 Daly, R.A., G.S.C., Mem. 38 p 258 quartzites and schists outcropping along the boundary west of the Kootenay river. To this series he gave the name Priest River Terrane. The area underlain by these rocks lies along the Kootenay River from Kootenay lake to the boundary and thence 2 west for a distance of miles. 2 Walker, J.P., G.S.C., Mem "148 map y 18' Lithology; Daly found that this series comprised a number of formations running in bands roughly north-south. These he numbered from A. to G. but had considerable difficulty in obtaining much definite information regarding them. To the west they form a hetrogeneous group of rocks 42 including biotite, chlorite, and serecite schists, sheared quartzites and dolomites. On the western contact there is a predominence of schist but, a mile to the east^beds of dolomite up to 450 feet thick are common. At this point, in fact, the dolomites are more plentiful than at any other place. East of this zone again the dolomites appear to die out and schists again predominate. Here dark, greenish grey phyllites occupy the area. These in turn, phase into sheared quartzites intercalated with narrow bands of serecite and chlorite schist and dolomite. Profound metamorphism of these rocks have taken place near their contacts with the major granitic intrusives extending a distance of two miles from the actual contact. There the micaceous minerals have, been altered to large crystals of biotite and muscovite completely altering the appearance of the rock. This metamorphism becomes more widespread going east where the dominant rock is a highly sereritic schist with large biotite crystals extensively developed along the plains of schistosity. Pale red garnets are also common. In places remnants of but slightly altered, sheared quartzites are found showing what the original rock has been. The rocks on the eastern margin of the area, next the Kootenay River, show the greatest amount of metamorphism. 43 The intrusion of two large batholithic masses has added the finishing touches to the dynamic metamorphism which had already obscured the original nature of the rock. The effect has been to turn the original rock into schists of various kinds with a very high development of rnuscovite and biotite. Tourmaline, epidote and red garnet have commonly developed. Daly has ascribed a thickness of 18,000 feet to this series but the difficulty of measuring a series in which the repetition of beds cannot be seen clearly is enormous. Age and Correlation; Daly experienced great difficulty in determining the age and structure of this series on account of the intense metamorphism and the difficult nature of the physiography. He finally placed them in the Precambrian and suspected them of being Pre-beltian. He found that they are identical, in part, with the Upper Selkirk of McConnell and Brock3 WHO BELIEVED THEM to be Cambrian, TlifeBt Koolenay Sheet G.S.C. and was able to show that the Kisconlith-Selkirk series on that map were reversed. Daly considered the Irene Conglomerate to 4 be a basal member of the Purcell series hut Drysdale suggested that they were the 4""Drysdale. G.S.C., Summ~Rpt 1916 p 61 basal member of a younger series. This made it possible to correlate the Priest River Terrane with Schofields Purcell 5 Series as exposed across the Kootenay River. 44 Ffalker, J.F. G.S.C., Mem 148 p 16 Table 1 According to Walker the most likely correlation is with the lower members of the Lower Purcell series as exposed in the Cranbrook Map Area. The SIMMST SERIES Distribution; This series lies to the west of the Priest River Terrane and extends in a band along the boundary to within about fifteen miles of the Columbia river. They also extend north almost to the West Arm of Kootenay lake although here they are considerably broken by granitic intrusives. Daly has found them to be 32,000 feet thick. Age and Correlation; When first described by Daly1 he correlated 1 Daly R.A., G.S.C., Mem 38 p 141 them with the Purcell Series, assuming that the Irene con-glomerate represented a basal member lying unconformably over 2 8c 3 the Priest River Terrane. In 1916 Drysdale worked in the Ymir area and,while 2 Drysdale, C.W., G.S.C., Mem 94 pp 25 and 149 3 Drysdale, C.W., G.S. C. , Summ Rpt 1916 p 60 accepting Daly's classification,was far from satisfied and later suggested that Daly*s Priest River Terrane might be the metamorphosed equivalents of the Lower Purcell series with the 45 Irene conglomerates as a basal member for some younger series. Later Bancroft correlated the Toby conglomerate with the Irene conglomerate as reported and accepted by Walker1. The Summçt series may,therefor, be assumed to be the T"Walker, J.F., G.S.C., Mem 148 p T 5 equivalent along the International "Boundary of the Windermere Series to the north and therefor at the top of the Beltian. Irene Conglomerate Lithology; This series is the basal member of the Summét Series and is, as its name implies, a conglomerate. Daly records a profound unconformity with the Priest River Terrane. The thickness as measured by Daly is nearly 8,000 feet. He implies a doubt, however, by suggesting that they may have been forset beds and the thickness, therefor, in-correct. The pebbles forming the conglomerate are well worn and rounded and are up to a foot or more in diameter. They are mostly composed of quartzite and smaller pebbles of dolmite. Occasional pebbles of phyllite and biotite granite are seen. Some angular fragments of porphyrite and diabase are occasion-ally seen from the overlying Irene volcanics. All these have been deformed by mountain building. The cement was probably impure, sandy muds which have been metamorphosed into schis-tose and crystalline rocks. Metamorphism is severe with the 46 accompaniment of the usual development of metamorphic minerals. Baly notes with interest that, while there is little doubt that the conglomerates were formed of material derived from the formations of the Priest River Terrane the rocks bounding the ancient beaches were much less metamorphosed than they are today and that the conditions that produced the great develop-ment of mica and serecite was impressed at a later period. The absence of feldspathic material is also noted by Daly who concludes that any Priest River Terrane granitic intrusive had not been exposed by erosion as yet* The Irene Volcanic formation Lithology; This formation overlies the Irene con-glomerates conformably being, in fact, interbedded with the upper members of them. They consist chiefly of a number of thick, basic lava flowe in which a few subordinate layers of basic tuff, a thick band of conglomerate breccia and a strong bed of dolomite are intercalated. Daly assumes 6,OO0feet to be the thickness measured conservatively. Typically the rock is a highly altered andesitic lava, now greenstone. It is a dark greenish-grey schist; the amygdules being drawn out into thin lenses. No primary minerals could be distinguished the thin section showing a mass of uralite, chlorite, epidote, quartz,calcite, limonite, serecite, saussarite with bitoite, magnetite and ilmanite developed as accessories. Occasional altered broken plates of plagioclase are seen. 47 The Monk formation; Lithology; This formation overlies the Irene volcanics conformably and Daly estimates 5,500 feet as a minimum thick-ness for it. The original nature of the rock evidently varied from quartz sandstone to argillite which metamorphism has altered to sheared, serecitic, light greenish grey quartzites and phyllitic slates. The only type not included between these two is the occurence of the conglomerate beds. The usual metamorphic minerals are developed. The Wolf formation; Overlying the Monk formation confor-mably are a mass of very heavily bedded sandstones, grits and fine-grained conglomerates which Daly has grouped as the Wolf formation. Lithologically they are identical with the coarser phases of the Monk. They are composed largely of a very massive, feldspathic quartz grit or conglomerate with thin beds of argillaceous sandstone. The larger pebbles of the conglomerate are of vitreous quartz or quartzite; occasion-ally slate, and are round to subangular. Daly estimates their thickness to be £,900 feet. The Dewdney formation The wolf grades insensibly into the overlying Dewdney formation which, while very similar, is finer grained and thinner bedded. 48 The main body of the rock is composed of well banded quartzites with intercalated thin beds of what may have been argillaceous sediments but which have been turned into a felt-ed mass of quartz, feldspar, biotite, serecite and iron oxides. The quartzite is similar to the fine grained phases of the Wolf formation. Rippie-markings are common throughout. Beds of conglomerate with pronounced cross bedding occur at two points in the upper half of the stratigraphic column. The pebbles are water worn and vary in size up to a foot in dia-meter, and consist of glassy quartz, grey or greenish quartz schist and, rarely, black slate. The cement is now a variable, schistose dark greenish-grey rock. Daly estimates its thick-ness to be 2,000 feet. The Ripple formation Conformably overlying the Dewdney formation is a heavily bedded mass of white quartzite to which Daly gave the name Ripple formation. The principle features of the occur-ence is the extremely well preserved ripple-marking at various horizons and exposed in a most spectacular fashion. Neither Daly nor Drysdale1 were able to 1 Drysdale, C.W.. G.S.C., Mem 94 p 22 detect any feldspar whatever, in fact the rock was composed almost entirely of quartz grains in a siliceous cement. The thickness of the formation proved to be 1,650 feet. 49 The Beehive formation This very thick, 7,000 feet and hetrogeneous for-mation lies conformably on the white quartzites of the Ripple formation. The formation consists principly of thin-bedded quartzites metargillites and serecite schists with one bed of light grey limestone. Some feldspathic phases of quartzite were seen in the field. Dynamic metamorphism has been very severe converting the metargillites to phyllites and is more pronounced towards the top of the formation. Ripple-marks, rill-marks, sun cracks, and occasional annelide trails and borings are common. The Lone Star formation. This formation forms the top of the Summit series and rests on the Beehive formation. Daly found an unconfor-mity between the two formations but believes that he may have been deceived by the wild disorder the intense metamorphism has produced. For this reason, too, the 2,00<>feet of strata measured by him can be taken as a rough indication only. The formation consists of dark-grey or greenish grey, carbonaceous phyllites with greenish serecite-quartz schist and then interbeds of light grey quartzites. The Pend D»0reille group Distribution; This group covers an area lying to the west 50 of the Summit series, and extends from a point two or three miles east of Belson south to the International Boundary along which it runs to the west to within about four miles of the Columbia River, It like the Summit series is considerably cut up by granitic intrusives. The boundary between it and the Rossland volcanic Group is not very clear, and may even be imaginary, Lithology; The rocks of this group consist chiefly of metamorphosed sedimentary rocks, including dark argillaceous and arenaceous members which have been altered, near the gran-ite contact, to andalusite and mica schists. Phyllites, met-argillites, impure quartzites, altered tuffs and siliceous marbles are present in certain localities. Age and Correlation; Daly1 found a considerable thick-ness of Daly, P..A., G.S,C.. Mem 38 p 271 of limestones and schists overlying the uppermost member of the Summit series with apparent conformity. Intense dynamic metamorphism produced by the orogenic movements that have flung the strata into the wildest disorder combine to make the task of disentangling the puzzle a most arduous one, Daly, as a consequence, suspected the presence of a discon-formity and tentatively placed the Pend D'Oreille series in the Carboniferous on lithological similarity with the strata of that age at Rossland. He also points out that this series 51 corresponds with that defined as the Nisconlith by McConnell 2 and Brock who 2 West fcootenay Siheet G.S.C.» Map 792 considered it to be lower Cambrian. Lithological similarity with the Slocan series was noted both by Daly and later Drys-3 dale but since the Tlbrysdale R.A.. G.S.C.. Mem 94 p"%7 age of this series was still in dispute not much help could be obtained from this source. 4 In 1917 Bancroft definitely established the conn-ection 4""Bancroft» M.F»» G.S.C.. Summ. Rpt. 1917 p 29B between the Slocan series and the Pend ©»Oreille series and the age of both was assumed to be Carboniferous on the evid-ence of fossils found in the former. This was accepted by Walker5 in 1926. Further FWalker. J.F.. G.S.C.. Mem 148 p 18 Map. fossils found in the Slocan series in the Slocan Area by „ . 6 Cairnes (TCairnes, C.E.. G.S.C., Summ Rpt. 1928. p 99A were determined and fixed the age of that series as Triassic. The Pend ©»Oreille series is, for these reasons judged to be Triassic. 52 The Hossland Group Distribution; In the area to the east of the Colum-bia River, the rocks of the Rossland group are quite widely developed covering the whole area west of the Pend D.Oreille series to the Columbia and south of the Kootenay river except where it is intruded by large masses of granite and one area in the middle that is underlain by the Beaver Mountain group. The detailed description of this group will be deferred until the account of the Rossland Area is taken up. Igneous Rocks At the close of the Triassic the orogenic movements common to the whole of British Columbia were felt here as elsewhere and resulted in the extensive intrusion of granitic masses and accompanying igneous stocks of Jurassic age. These will be taken up in detail on the Chapter on Igneous Rocks. The Beaver Mountain Group Distribution; As mentioned above this group occurs in a patch overlying the Rossland Volcanics lying some ten miles east of the Columbia River and the same distance from the International Boundary. Lithology; Two different types of strata are common; sediments and volcanics. The former consists of water lain, 53 dark, thin bedded shale and greenish grey sandstones. One stratum of massive conglomerate is present. The sandstones grade into thick beds of tuffs and volcanic breccia which are alternated with vesicular flows. Over 1,000 feet of these sediments have been measured by Daly. Pebbles of granite, quartz and slate have been observed in the conglomerate. The volcanics consist mainly of augite andesite with minor quantities of Olivine free basalt. Chemically the pyroclastics are similar and are obviously derived from the same magma. They are very sililar to the flows of the^oss-land group but show very little metamorphism. 1 2 Age; Both Daly and Brock recognised this group as being T"l)aly R . A .. G.S.C.. Mem 38 p 352 1T"West Kootenay Sheet G. S. C., Map 2927 younger than the underlying Rossland Volcanics but were unable to ascribe a very definite age to it. Brock placed it tenta-tively as Post Cretaceous. Both suggest the possibility of other areas of the same formation occuring that have not, as yet, been separated from the Rossland Group. The Beaver Mountain Group is the youngest rock in the area with the exception of the recent gravels and clays and the glacial overburden. 54 4 Rosaland Section The next area to be considered is that along the International Boundary between the Columbia River and Christ-ina lake and north to Arrow lake. This section is also known as the Rossland Mountains1 area 1 Daly. R . A .. G.S.C.. Mem 36 p 319 since it contains that range of the Columbia System. Pend ©»Oreille Series The oldest rocks known in the area are the members of the Pend D*Oreille series which lie along the Boundary for about five miles and are an extention across the Columbia, of the larger exposures to the east of that river. As these have already been described no further mention will be made of them. Several patches of rocks occur scattered over the area that Daly considered to be Carboniferous and contempor-aneous with the Pend D*Oreille series. Recent work has shown the latter series to be Triassic so that it is possible that the remnants described by Daly may either be older than the I Pend D*Oreille or else that they are younger than Daly bel-ieved. They consist in the main of Carbonaceous limestones and breccias and are bedded with tuffs in many places. 55 KcConnell and Brock both found fossils in them but in a very poor state of preservation. Sutherland Schistose Complex Distribution; An exposure of rather greater size is that of the formation called by Daly the Sutherland schistose complex. This formation covers the area to the east of the lower half of Christina lake and between it and the western limit of the Coryell batholith, Lithology; The whole formation is highly complex in nature being very thoroughly metamorphosed and, as a conse-quence the stratigraphy and correlation almost impossible to arrive at without an undue ammount of field work. Crystalline schists of all sorts are common, the commonest being garnet schist, serecite schist, biotite-epid-ote schist, actinolite-biotite schist and so on. Some marble is present in irregular beds and with it is greenish, massive quartzite, With these sediments are associated many irregular bands of gneissic gabbroid rocks and amphibolites. Daly concludes, form the presence of these old and highly altered formations, that there is a probability that the whole west slope of the Selkirks and the east slope of the Columbia mountains is underlain by old rocks equivalent to the Pend D'Oreille series and possibly ranging through the top of the Paleozoic into the Triassic, 56 The Rossland Volcanic Group Distributions This series of rocks is developed all along the Boundary in a narrow belt and two belts run north at each side of the area about half way up to Arrow lake, A narrow belt connects the northern extremities of the two north-south zones. The extensive development in the area to the east of the Columbia river has already been described. As originally defined this group comprises the Hall series of the Ymir Map area, the augite porphyrite and the Mount Roberts formation of Rossland and the Rawhide, Brooklyn and Knob Hill formations of Phoenix.1 1 Le Roy. O.E». Guide Book No 9 p 64 The Hall Series 2 Lithology; These have been described by Drysdale as a series 2 Drysdale. C.W., G.S.C., Mem 94 p 27 of sedimentary formations within the volcanics of the Rossland Group proper. In the Ymir Map Area Drysdale worked out the thickness to be 7,000 feet. They consist mainly of coarse to fine conglomerates, (arkosic) sandstones, and argillites; all considerably altered. The conglomerates are very hetrogenius and are composed of pebbles of a mixture of the olderjformations. 57 The sandstones are generally red in colour. Age and Correlation; Drysdale believes that they were largely laid down subaerially, probably on a delta into the epicontinental sea during a lull in the volcanic activity. He suggests a land of moderate relief and a semi-arid climate with 1 seasonal rainfall « 1 Barrel!, J.. Jour of Geol 1908 pp 292, 293. Drysdale correlates this series with the Nicola 'series in which Triassic fossils have been found. The members are also related to the Rossland Volcanics with which they are interbedded and which are believed to be Triassic: They may therefor be considered Triassic. The Mount Robson formation This is the oldest formation found in the Rossland 2 Map Area and has been described by Drysdale. IHbrysdale, C.W.. G.S.C., Mem 77 pTSIf Lithology; It consists essentially of highly sillici-fied slates some of which are carbonaceous and calcareous. Interbedded with these is a thick series of tuffs, the whole formation having a thickness of 1,200 feet. Age and Correlation; In 1906 Brock found some poorly preserved fossils that have been tentatively determined as Upper Carboniferous. Drysdale indicates a correlation with 8 3 Le Roys Knobhill and Brooklyn 58 T"le Roy, O.S,t G.S.C.» Mem 21 pp 30-54 1 2 formations at Phoenix and with Dawsons Cache Creek Group in TTDawson» S.K., G.S.C.» Ann Rpt Vol Vll 1894 p 57B 2 Drysdale, C.W., G.S.C., Summ Rpt 1912 pp 130-132 the Eamloops District. They are believed to be a part of the Rossland formation, however, which has been assumed to be Triassic.. The Augite Porphyrite Sills, Flows and Pyroclastics The rocks included in this group are extensively developed throughout the area being considered. Lithology; They consist mainly of flows, intrusives and pyroclastics having the composition of augite porphyrite, augite-feldspar porphyrite, amygdaloidal basalt and a few similar types. These have generally been considerably altered and sheared, fresh specimens being rare. The augite porphyrite is the commonest type and is 3 described by Drysdale as being a dark greyish to greenish black rock with augite rDrysdale, C.W., G.S.C., Mem 94 p 50 phenocrysts in a dense groundmass. In places it assumes a brecciated structure which Drysdale, quoting from G.A. Young, believes to have been formed by an injection of material be-fore the initial injection was fully cooled. In thin section 59 phenocrysts of augite, hornblende and plagioclase are seen in a fine groundmass composed chiefly of hornblende and feldspar. The hornblende is probably mainly secondary after the augite and the feldspar is labradorite. 4 Daly describes these flows very fully, giving a number of analyses not recorded here. He points out the 4 Daly. R.A., G.S.C., Mem 38 p 525 variation in composition among the various members of the series. Probably a part of the same series is the Volcanic agglomerate that overlie the Mount Roberts formation. These are composed of fragments from dust to blocks four feet across and appear to be entirely unsorted by water. Age and Correlation; The Rossland Volcanic group has been tentatively correlated to the Nicola group of Dawson^ 2 and is therefor considered to be Triassic, Cairnes believes TTftrysdale, C.W., G.S.C., Summ Rpt. 1912 p T5!T 2""Cairnes, C.E., G.S.C., Summ Rpt 1928 p 99A them to be the equivalent of the tuff beds found in the Slocan series in the Slocan Map Area which he definitely de-cided to be Triassic. JURASSIC IGNEOUS INTRUSIVES A widespread amount of igneous activity took place to-60 wards the close of the Jurassic as an accompaniment of the Jurasside revolution. The results have produced the following bodies of igneous rocks; The Diorite Porphyrite, the Trail batholith, the Andesite flows and pyroclastics, the Rossland Monzonite and the Augite Latites. These have all been more fully described in the chapter on igneous rocks. SOPHIE AND LAKE MOUNTAIN CONGLOMERATE Distribution; Rocks of this formation occur at two main points in the area. The main exposure occurs at Sophie Mountain on the International Boundary about half way between the Columbia River and Christina lake and the second a few miles north of the boundary^on Lake Mountain to the south and east of the Town of Rossland. Two other small patches occur on the Boundary to the west of the one on Sophie Mountain. Lithology; Daly describes these coarse, massive con-glomerates whose pebbles are composed of grey and greenish quartzite siliceous grit, quartz, phyllite and slate. With a few pebbles apparently of granite. On Lake Mountain no pebbles of trap rocks of the Rossland Volcanic group are to be seen but on Sophie mountain a few appear while in the two most westerly occurences they are quite common. The cement is generally arenaceous. Age and Correlation; While it is assumed that all the 61 exposures are of the same age that is not a definitely estab-lished fact, Daly points out that going from east to west the pebbles become more and more rounded and the number of them that are found of the adjacent Rossland Lavas rapidly increases. He suggests that they "represent a heavy mass of river gravels, and that one or more streams flowing westward from the site of the present axis of the Selkirk range were responsible for the accumulations. The deposit of dicotyledefcous leaves in the ,coarse Sophie Mountain conglomerates strongly indicates the fresh-water origin of that mass at least.—---—-- The high probability is that they are all pre-Miocene and post-. . 1 Jurassic.* 1 Daly, R . A ., G.S.C., Mem 38 p 552 Drysdale has put them tentatively in the Eocene. TERTIARY IGNEOUS ACTIVITY The renewal or continuation of the causes producing the Mesazoic intrusives lead to the introduction of further igneous rocks during the early Tertiary. These have been described in the chapter on igneous rocks and will only be mentioned here to preserve the continuity of the record. They are the Porphyritic Monzonite in the Rossland area and the Salmon River monzonite in the Ymir area which may be closely related. Following them are the widespread 62 intrusives of the Coryell batholith which are typically alka-lic syenites and pulaskite. Closely related to them are the Sheppard granites and granite porphyries and probably related to the whole epoch of igneous activity are the widespread lamprophyre dykes. The record of igneous activity appears to close with the Miocene. As a result of the widespread glaciation, a mantle of glacial detritus covers the greater part of the district. 63 THE BOUNDARY SECTION. This area includes the country lying to the west of Christina lake along the International Boundary to include the parts round the towns of Phoenix and Deadwood and extending north to the contact with the Nelson batholith. The earliest work in the area was done by Brock1 in 1901 1 Brock. R.W., G.S.C., Summ Rpt 1902 2 and 1902; at a later date Daly examined the area in connection 2 Daly. R.A.. G.S.C., Mem with his survey of the International Boundary. The area was 384 next visited in 1908, 1909 and 1910 by Le Ro^, 3~Le Roy, O.S., G.S.C., Mem 19 4 Le Roy, 0.3.. G.S.C. Mem 21 The Grand Forks Schists Distribution; These are the oldest rocks in the area and occur widely developed in the vicinity of the town of Grand Forks and south to the International Boundary along which they extend about half way to Christina Lake. Lithology; Daly describes these rocks as being a group of schists so highly metamorphosed that their primary 64 nature is often in doubt. He considers the greater part of them to be basic extrusives of andesitic or basaltic compos-ition with minor intrusives and sedimentary argillaceous rocks. Age and Correlation; Brock states that "These rocks have a strong lithological resemblance to the Archean rocks of the Shushwap series and are the oldest rocks found in the 1 area.* Walker TWalker, J.g.» G.S.C., Summ Rpt 1928 p 123 A has shown that the series formerly called the Shushwap at Ainsworth is the same as the Ainsworth series and Beltian in age. Daly, however, favours the opinion also voiced by Brock that they may be more highly metamorphosed members of the argillites and limestones found elsewhere in the area. No age can therefor be assigned to this formation. The Knob Hill Group Distribution; This group of rocks underlies large portions of the area and possibly the whole of it beneath the overlying younger formations or where not stopped out by in-trusives. Lithology; Le Roy describes the rocks as cherts, jasperiods and tuffs with small redidual masses of argillites and crystalline limestones. The jasperiods are grey in colour and consist of a 65 series of pebble like chert fragments embedded in a matrix of calcite, quartz and chlorite. The rock is originally believed to have been sometimes a tuff or more commonly a limestone and the present character produced by a partial silicification along capillary openings. The cherts are grey to bluish, dense, silicious rocks and are believed to have been derived in a similar manner from tuffs or argillites. The tuffs are fine grained, dense rocks and show partial alteration to jasperiods and cherts in places. The whole series shows intense sillicification whose source Le Roy is at a loss to account for. He suggests a deep seated igneous body of which the quartz porphyrites are off shoots. Probably related to the above tuffs Le Roy found a considerable development of a highly altered porphyrite. Mineralogically they are very similar to the tuffs and occur in two groups. One probably extrusive at the same time and the other intrusive into them. The exact age of the latter group has only been guessed at and Le Roy suggests that it may correspond to Brocks PhoeniK Volcanic Group. Age and Correlation; Le Roy believes this group to be Paleozioc but Drysdale1 has correlated them with the Mount Roberts 1 Drysdale, C.W., G.3.C., Mem 77 p 66 formation which is considered to belong to the lower Triassic Attwood Series This is the name that has been given by Brock to a series of metamorphosed sedimentary rocks that outcrop widely over the part of the area lying west of the town of Grand Porks, Together with the Knob Hill formation it has been 2 correlated with the Rossland volcanic group • It is in the members of this series that the ore 2 Le Roy, O.E. , G.S.C., Guide Book No 9 p 62~ bodies of Phoenix and Leadwood lie. Le Roy has divided it into two main groups.; the Brooklyn and the Rawhide. The Brooklyn formation This is the lowest member of the Attwood series. Lithology; The prevailing rock composing this for-mation is a limestone which has suffered various degrees of metamorphism. Typically it is compact and crystalline throughout with a varying grain. The colour ranging from grey to pure white. The first degree of metamorphism gives a rock which consists of small oval grains of chert embedded in a matrix of light grey crystalline limestone. Further metamorphism 67 results in an increase in the silica content until areas of pure chert of considerable size are produced. This rock has 1 2 been called a "Jasperiod" by Spurr • Le Roy suggests 1 Spurr, J.E., Mono.51 p 219 U.S.G.S. "Geology of Aspen District** 2 Le Roy. Q.E., G.S.C., Mem 21 p 37' a common origin for the Jasperiods of both the Knob Hill and Brooklyn formations. He believes that ascending siliceous solutions replaced the limestones differentially effecting the metamorphism and that these solutions came from a deep seated source. He further suggests that the main batholith at an early stage in its invasion may have been this source. Together with the Jasperiods, occurs a series of tuffs and argillites. There is no doubt that these occured as inter-beds in the limestones. Associated with them are a number of dykes and sills of porphyrite. Extensive mineralization hs.s occured in places replacing the limestone by epidote, garnet, etc and in these zones all the low grade ore bodies of the Phoenix region occur. Age and Correlation; Daly considered this formation to be similar to rocks he believed to be Carboniferous in the Rossland area and which have since been assumed to be Triassic. The correlation between them and the Hall and Mount Roberts formations seems to be very reasonable and they may therefor be assumed to be Triassic. 68 The Rawhide formation This formation is confined to the Phoenix area where it has a limited occurence. Lithology; It consists of a dark, slightly carbone-ceous argillite, thinly-bedded. Age; It appears to overlie the Brooklyn formation conformably and is the upper member of the Attwood series. It may therefor be considered to be a part of the Triassic Ross-land Group. After the deposition of the above formation an ele-vation of the land took place with a consequent cessation of sedimentation and an accompa.nying period of igneous activity. The igneous rocks intruded during this time will be mentioned here only as they will be described more fully in the chapter on Igneous Rocks. They are; the Diorite Porphyrite, the Gas-cade gneiss and the various igneous stocks, dykes etc, related to the Nelson batholith. The Kettle River formation Distribution; This formation has a rather limited development occuring only in a narrow band running in a north-south direction through the eas end :f the town of Phoenix. Lithology; The formation consists mainly of conglo-69 FeUifia/iit *mds/d*tsrt cier/f wt'(/< merate^contain pebbles of the Knob Hill group. , Age and Correlation; LeRoy believes this formation to be a fresh water deposit and may even be the delta into an old lake the basin of which has since been eroded away. The for-mation has been definitely determined as Oligocene on fossil 1 evidence. Daly found the Kettle River formation to overlie his Anarchist series T"Paly, R.A., G.S.C., Mem 38 p 594 unconformably. This series does not occur in the area, however, but the lower contact of the Kettle River series is always unconformable. Daly gives a thickness of 2,100 feet for the formation but is probably unreliable. The Midway Volcanics Distribution; This formation is developed along the International Boundary for eleven miles with the town of Mid-way near its eastern limit, and extends north for about fif-teen miles. A considerable exposure also occurs to the east 1 of the town of Phoenix. LeRoy concludes that the entire area had, at one time, been covered 1 LeRoy. O.E., G.S.C., Mem 21 p 44 but that subsequent erosion has removed a large portion of it, laying bare the older formations beneath. Lithology; The formation consists of a series of lava 70 flows of composition varying from basalt to trachyte. Vasi-cular or amygdaloidal types occur but are not common. They vary from light brown to black with white feldspar phenocrysts. Daly found nine different types of lava including, olivine basalt, augite andesite, hornblend-augite andesite, biotite-augite andesite, hornblende-augite-biotite andesite, biotite andesite, trachyte, extrusive rhomb-porphyry and an analcitic lava. Tuffaceous beds also occur. Only the trachyte is developed at Phoenix. Age and Correlation; LeRoy found that a period of erosion had intervened between the formation of the Kettle river formation and the outpouring of the Midway Volc-anics. Both he and Daly therefor place them as post Oligocene and probably Miorene. SUMMARY OF THE S2DIM3I.rTAP.Y GEOLOGY The record of the sedimentary geology of the dis-trict opens in the Cranbrook Map area during Beltian time. The age relationship of the rocks formed then in B. C. with the Precambrian sediments in other parts of the world is not definitely known but it is evident that it represents the top of the Precambrian since it has been shown to underlie the Cambrian without marked unconformity. Lower Purcell Series. The oldest sediments con-sist of a succession of siliceous grits and argillites with minor amounts of limestone forming the Lower Purceljts 71 The Epoch was closed hy a period of vulcanism of relatively minor importance. Upper Purcell series. Overlying these with hut slight unconformity are the formations of the Upper Purcells. These have a rather wider distribution being found in the Winder-mere Map area and along the Kootenay lake as well as to the east of the Cranbrook Map area. In that area only the bottom is exposed the remainder, if deposited, has since been removed by erosion. They consist of similar rocks to the Lower Pur-cell's but with a higher proportion of limestone. Windermere series. Resting, with marked unconformity, on the top of the Purcells is the series of formations known variously as the Windermere series, the Ainsv/orth series, and # the Sumrriet series. They are developed extensively in the Kootenay lake area, the Ainsworth area and the Ymir section, and are also present in part in the Lardeau, Windermere and Slocan Map areas. Generally the base is a conglomerate for-mation grading upwards into schists, quartzites, fine con-glomerates, argillit.es, and liirestones. In the south, on the Boundary, a. considerable amount of volcanic material appears, giving an indication of volcanic activity there during the lower Windermere time. Paleozoic Era Closing the Precambrian is a marked unconformity and deep erosion that still does not appear to have been accompanied by much mountain building. On this 72 erosional surface early Paleosoic sediments were laid down in the Windermere Area where a fairly continuous record of sed-imentation was continued to the close of the Devonian. Prom the Upper Cambrian, the earliest Paleozoic period to be re-presented, a succesion of limestones and argillites with minor amounts of sandstone and conglomerates were laid down until Ordovician time. During the Ordovician the seas were drained and, on the erosion surface so formed, a. further succession of quartzites grading upward into limestones ran from Upper Ordovician to the close of the Silurian. On the eroded sur-face of these strata shales and limestones of Devonian age were laid down. Mesozoic Era. During the Paleozoic except for some Devonian limestones in the east of the Cranbrook area, no sedimentation was going on elsewhere in the area. With the closing of the Paleozoic the disturbances of the Permian, or Appalachian revolution, brought about wide flooding of the land and sedimentation once more took place in the Lardeau, Kootenay Lake, Ymir, P.ossland, Eoundary and Slocan districts. In the Lardeau and Kootenay lake this was commenced in the Carboniferous but in the other parts it appears not to have commenced until the early Triassic. The early sediments were argillites, limestones, sandstones and conglomerates, but very soon the entense vul-canism that produced thousands of feet of tuffs and agglomer-ates during Triassic times all over British Columbia and 73 Chapter IV Igneous Geology The long and complicated history of the igneous, and par-ticularly the plutonic, geology of the area is a problem that is far from being unravelled. The obvious facts reveal the many periods of intrusion as well as the great number of relat-ed intrusives. The relationships of one to another and to the mineralization is far from clear and dependent on the whole theory of batholithic invasion which is itself still an obscure problem. Owing to the number of men that have worked in al-most as many different parts of the area correlations are generally the merest speculation and, for the purpose of detail study, each section will have to be delt with separately as with the sedimentary formations. Afterwards some conclusions will be attempted. A graph has been drawn on which the granitic rocks whose analyses could be obtained have been plotted with respect to their content of KgO, and Ua20, and CaO, in an effort to dis-cover their relationships chemically. See appendix. 1 THE HOHTH-SAST OF THE HiLSOK BATHOLITH 75 The Poat Triaasio Granitic Intrusivea The period of crustal activity at the close of the de-poaition of the Slocan series resulted in the production of sweeping folds, and into these folds the granites of the Bath-olith were injected and have since been exposed by erosion. This batholith is a very complex one and the presence of several periods of intrusion are at once apparent. The most extensive of the recent work is that done by Sairnes in 1928 in the Slocan and Upper Arrow Lake areas and r~Calrnes. G. I. G.S.G. Sumrn Rpt 1926 p 10QA that will now be discussed as a type section. Gairnes recognizes two main batholiths intruded at diff-erent timea the earlier of which he calla the Nelson batholith and the later the Xuskanax batholith. He further subdivides the Nelson batholith into three members known respectively as the Nelson Gabbro-Gneiss, the Nelson Granite and the Nelson Pegmatite-Gneiss Complex. The Nelson Gabbro-,gneiss These rocka occur in a narrow band having a maximum width of one and a half miles and running in a northwesterly direction and having their southern extremity about a mile from the east shore of the Upper Arrow Lake just north of Nakusp and crossing the lake some eight miles north of that town. Age and Correlation; Where the Kuskanax batholith is in 76 contact with this rock it shows every evidence of cutting it from which it is argued that it may he correlated with the Kelson batholith. To support this Gairnes suggests the sim-ilarity in their composition and the extent of deformation. He takes the relatively basic composition to imply an early phase of the intrusion. Lithology; It is a medium-grained rock greenish in colour and carrying more than bOfo of ferrornagnesian minerals. These are predominently a dark green amphibole (Hornblende), epidote and small quantities of biotite. Plagioclase makes up the greater part of the remainder of the rock although some quartz is present. Deformation has strongly foliated the rock and along the shear zones of the gneiss alteration to a chlorite mineral is considerable. Pyrite is quite ubiquitous. The Nelson Granite Distribution; Two exposures of this rock are present in the area. A tongue crostes the head of Slocan lake in the vicinity of Rosebery and another mass of it appears just be-low the south end of Upper Arrow Lake. There is some likeli-hood that these two areas may be connected since the geology between the two has not been worked out. Litholofi'y; The Nelson Granite is typically a medium to coarse-grained rock in which large crystals of orthoclase and occasionally microcline are conspicuous, giving it a character-istically porphyritic texture. The rock has been classified as a granite although it phases into granodiorite and quartz 77 diorite in places. The essential minerals are quartz, orthoclase, and plag-ioolase. Hornblende and biotite are present in minor quant-ities. Where the Nelson granite phases into the Nelson peg-matite-gneiss complex, muscovite is characteristically present. The plagioclase is generally albite to albite-oligoclase except in the quartz-diorites when it phases into oligoclase-anaesine. The rock is generally massive, and although crushed and foliated in places, not commonly so. The extensive mineralization of the Slocan district is commonly ascribed to this rock. Not only is the overlying Slocan series heavily mineralized but the granite itself has proved a host for valuable ore deposits. The inference at least is obvious that no earlier phase of intrusion could have been responsible for the presence of the mineralizing solutions. Age and Correlation; The relation between this rock and the one that forms the subject of the preceeding section can-not be accurately determined since they have never been observed in contact. It is, however, assumed to be younger on grounas that have already been mentioned. The Nelson Pegmatite-gneiss Complex Distribution; This member occupies a considerable portion of the map area west of the southern part of the Upper Arrow Lake. Lithology: It consists of two distinctly different types of rocks, one a typically pegmatitic granite and the other 78 distinguished by a well-developed gneissic structure, which are in intimate association. The pegmatite is essentially a coarse-grained rock with an uneven texture and contains quartz, plagioclase, orthoclase and muscovite as essential constituents. Tne quartz is very abundant and has a smoxey appearance and is but little strain-ed, The plagioclase is white and its crystals vary greatly in size. It is very finely twinned and tne twinning lamellae ap-pear to die out before reaching the boundary of the crystal. Pegmatitic intergrowths are common. The muscovite occurs in books up to half an inch in diameter. Sere cite is a common seoondary mineral. The other phase has a greater uniformity of texture and can be easily distinguished by its gneissic structure. The pegmatite has been observed both cutting it and grading into it but never appears to have been earlier. It is a medium-grained, grey, finely laminated gneiss except for some localities where this structure is not apparent and the rock seems to be comparatively fresh. The presence of red garnets is a distinctive feature, and a vuggy or pseudom-iarolitic texture, in the cavities of which crystalline cluster of amythistian quartz, calcite, limonite, and black tourmaline occur, is common. The rock has rather a granular appearance in thin sections suggesting recrystallization and derivation at least in part, from pre-existing rocks. Quartz is abundant and little strained while plagioclase is commoner than ortho-79 raicrocline very rare. Both biotite and muscovite aye common and aereoite occurs as a secondary mineral. Micro-pegmatitic intergrowths are not uncommon. Sphene, magnetite, iron oxides, chlorite, kaolinite, red garnets and sulphides are common accessory minerals. They have been classed as rang-ing from binary granite to quartz monzonite. In places inclusions of Precambrian rocks are so common that Cairnes1 had considerable difficulty in drawing a boundary 7~gairnea. G.F. G.S.C. Summ Rot 1928 p 102A between the complex and the true Precannrian rocks. Cairnes came to the following conclusion as the origin of the complex which is an interesting one. He believes that, "In working its way towards the surface, the Nelson batholith everywhere encountered and was forced to penetrate the Precam-brian rocks before reaching the later formations. The Precam-rocks were thus the first to be affected by the advancing bath-olith, Localities were noted where a single stratum could be traced along its strike from a rock definitely pre-batholithic in age to a banded gneissic rock the equivalent in appearance and composition of the gneiss of the pegmatite-gneiss complex. In fact the field evidence in general supports the view that the banded structure so characteristic of the gneiss might be attributed to conformity with bedding lamsllea of completely assimilated rocks. The conclusion is that the pegmatite-gneiss complex is, in essence, a deep-seated contact phase of the Nelson batholith with Precambrian rocks." 80 Age and Correlation: This rock is easily distinguished the other granites in the area although its boundary with the Uelson batholith is a gradational one. It appears to be less deformed and altered than the rocks previously mentioned and has therefore been considered later than them. The Kuskanax batholith Distribution; This batholith occupies an area lying to the east of the Upper Arrow Lake, and crossing it at the head. In width it extends from within a short distance from Upper Arrow Lake to a point west of Duncan Lake and then south to about half-way between Slocan Lake and Kootenay Lake and pass-ing a few miles north of the former. Its main trend is north-west and it is roughly eliptical. Llthology; The rock is, in general, a medium to fine-grained type which;along parts of the margin shows a well-defin-ed porphyritic texture. Cairnes has recognized two main types. One is a syenite which grades through a quartz syenite into a granite and is developed as an apophysis along the southern border of the main intrusive and tonguing into the sediments to the west almost to the shore of the lake. Elsewhere the rock is mainly granite wnich is generally finer grained than the syenite. Both rocks carry minor quantities of ferromagnesian minerals and are light coloured in consequence. Both types also have abundant orthoclase and microcline and relatively little plagioclase which occurs, when present, in the form of perthitic intergrowths together with both potash feldspars. til tjfttity in the granite if® is but little strained and occurs in considerable The characteristic mafic mineral is A dark green to "bluish-green amphibole partially altered and is, with the exception of occasional biotite, the only such mineral present. Accessory minerals are sphene, apatite, mag-netite, yellow garnet, and some sulphides while the following secondary minerals are present: kaolin, chlorite and calcite. A feature of the Kusxanax batholitn there observed by Cairnes is the remarkable paucity of mineralization in it or connected with it, which is a direct contrast to all phases of the Nelson batholith and the Nelson granite in particular. Age and Correlation; As mentioned, the rocks of the Kuskanax batholith have been observed cutting the Nelson Gabbro-gneiss, the only member of the Nelson batholith with which it comes in contact, and, on the strength of this evidence, Cairnes consideres the Kuskanax batholith to be younger than the Nelson. Additional evidence is the difference in the mineralogical com-crnJ nnfi/re. of position between the two as well as the degree^ uf. an. t "iiuurphiiijBi ttsd the accompanying metamorphism. The southern border of the blocan Map area between blocan Lake and Kootenay Lake and south of the Kaslo-Naxusp railway is underlain entirely with the granite of the Nelson batholith. This would appear to connect up with the Nelson granite of Cairnes and LeRoy1 says the following referring to it:-l. Lettoy. O.a. (i.ij.u. summ Rot T9TP pTF5" 82 "The rook varies from mica and hornblende granites to granodiorite and even more basic types. They range from med-ium to coarsely porphyritic in texture and in colour from light grey to almost white. Genetically connected to this batholith is the gr-eat series of sills, dykes and stocks of finer grained porphyritic varieties of the above plutonios, which are widespread throughout tne area, with the gre&test development in the rocks of the Slocan Series. " LeRoy's account is very incomplete but there is nothing in it that leads one to suspect this of being anything but a phase of the Kelson granite. The Kootenay Lake Map Area Distribution; Granites occur in tnree parts of this area. They lie to the west of the southern half of Kootenay Lake and are apparently continuous with the granites occuring in the southern part of the Slocan Map area. They also occur at the two points on the east short of the Upper half of Kootenay Lake. Lithology and Correlation; The granite mass to the west of the lake consists of a light ¿-'rey, porphyritic granite1 ITWalker. J.F. G.D.C. Surnm Rpt 1928 p 127a and appears most probably to be the Kelson granite. On the east shore of the lake dust north of Crawford Bay an outcrop of granite and pegmatite intrudes tne Lardeau series as sill-like injections, the sediments being themselves highly altered. 83 r ' i this is probably related to Gairnes Kelson Complex. The larger body further north is light grey and of medium texture and appears to be a pnase of the Kelson granite. The Lardeau and Big Bend Map Areas In this area both the Kelson and Kuskanax batholiths occur and mill be treated separately. The Kelson batnollth Distribution; The three main exposures of this formation occur in the area the largest being to the west of the Columbia River between Re^elstoice and Upper Arrow Lake. A large area of the Kelson batholith also occurs running east from Revelstoke along the Main line of the C.P.R. The last exposure lies im-mediately to the east of the above. Lithology; The area to the east of Revelstoke appears to be underlain by rocks similar to Cairnes1 Kelson Pegmatite-gneiss complex and have been described in some detail by Gunning. Here a series of mica schists, quartzites and limestones have been extensively intruded by irregular bodies of gneissic granite. In other places the rock showing resembles a true gneiss which Gunning suggests may be either a paragneiss or an orthogneiss. Pegmatite dykes cut the whole series. One mass nas been described by Jaly^ as ranging from au£ite—gubbro HfDaly. R.A. G.S.C. Mem 68 p liO through augite-diorite to fine monzonite and may possibly re-84 r i present a phase similar to Gairnes Nelson Gabbro-gneiss. Tne petrography, in general, is similar to that of the Nelson com-plex. One area examined in detail by Gunning is described as being a typical granite containing a large quantity of micro-dine and orthoclase 'and small amounts of Albite-oligoclase with abundant quartz. Micrograpnic intergrowths of quartz and feldspar are common. Accessory minerals were biotite, muscovite, apatite, sphene and pyrite. lied garnet is common in the pegmatitic phases. A few small crystals of beryl were noted. It is suggested that the whole complex represents the contact phase of a deep seated intrusive with Precambrian sediments. The pegmatitic phases seems to be the last pnase everywhere. In the more northerly part of the area a number of isolated outcrops of granite occur. These granites are all more or less porphyritic and are commonly characterized by the presence of microcline up to three inches long. The rest of the rock is composed^lagioclase, ortho^clase, quartz and varying amounts of green hornblende biotite, epiuote, sphene, apatite anu pyrrhotite. The plagioclase is zoned and ranges from oligo-clase in the center to aluite on the eages. They vary from granites to granodiorite. It seems highly probable that they are related to the Nelson granite. Walker and Bancroft con-sider the eastern granite mass to be of the same age and Gunning gives the following discription of a petrographic 85 study of the west end of it near Albert Canyon. He says that it is a "typical, rather fine-grained granite containing miorooline, orthoolase, oligoclase, quartz, biotite, Muscovite, titanite, apatite, and magnetite. Some of the plagioclase is zoned." Further east Yialker and Bancroft found it to be porphyritic. Age and Correlation: The area east of the Columbia and that round Revelstoke appears to be the same kind of rock and can be correlated on petrographic evidence with the Nelson Pegmatite-gneiss complex as described by Cairnes. Gunning1 rtkuraing. H.C. Summ Rpt 1928 p 148 places the age of the granites in the Big Bend Map Area as between early Jurassic and early Tertiary. The Kuskanax batholith Distribution; The northern margin of Cairne's Kuskanax batholith is exposed in the Lardeau running northwest from a point west of the head of Kootenay Lake to the head of Upper Arrow Lake. Lithology; It has already been described and the only new feature in the area is the presence of aplitic and dior-itic phases. Correlation; It has been traced to the part of the batholith worked on and named by Cairnesl and which he decided l*"~Cairnes. C.E. G.XC. Summ Rpt 1928 part A 86 was definitely younger than the Nelson batnolith. The Alnsworth Mao Area Two varieties of granites are recognized in this area by Schofield1; a gneissic phase and an unfoliated phase. 1 Schofield. S. J.. G.S.G., Mem. 117. p 19 & 20 The Gneissic phase Distribution; This rock occurs as dykes and sills intrud-ing the earlier sediments on the west side of Kootenay Lake in -the vicinity of the town of Ainsworth, and four larger masses in the same region having a general elongation parallel to the lake. Lithology; The rock is light grey in colour with a dis-tinctly gneissic texture. It has a fine-grained, even texture and is composed of quartz, feldspar, and biotite. The rock, in the thin section, can be seen to be distinctly crushed and the feldspar to be predominently orthoclase with minor amounts of microcline and plagioclase. Age and Correlation; Schofield points out the similarity in composition between these rocks and the Nelson granite and accounts for the development of the structure by supposing that the smaller injections had cooled before the cessation of the orogenic movements either on account of their smaller size or because they were intruded at a slightly earlier time. 87 xmw Unfoliated granite Distribution; This granite occurs ail along the western border of the area parallel to Kootenay Lake and two or three miles west of it. It is evidently a part of the same mass of granite observed round Arrow Lake and Slocan Lake. Lithology; The rock is light grey in colour and is mant/ characterized by large phenoerysts of pink orthoclase,, of which show Carlsbad twinning. The following is an analysis of the phenoerysts made by Gwillim1:- The Nelson granite was studied in some detail by Brock^ who records the analysis (1) given in table 2 appendix. T Gwillim. J.C.. Can Reo So Vol Vll 1897 p 295 i~Brook. R.W. G.S.C. Annual Rpt Vol XV 1902-1902 p 101A Sohofield also records another analysis (2) by Gwillim which is also given. Brock considers that the Nelson granite is intermediate between the alkali and the lime-soda series of rocks and is about on the boundary between granite and diorite. The contact metamorphism of the surrounding sediments is not very great. The regional metamorphism is, however, more severe; argillites being changed to andalusite schists and limestones to marbles. p Age and Correlation; Schofield^ has snown that the 2 Schofield. S.J. G.S.C. Mem 76 pp 95-97 revolution producing the mountain building conditions under 88 which the intrusion of the granite took place at the close of the Triassic and continued at intervals throughout the Jurassic and possibly even into the Cretaceous. He found granite pebbles in the Upper Cretaceous formation in the vicinity of Blairmore showing that the intrusion of the granite was effected at a previous date and that sufficient time had elapsed since its injection to unroof the batholith at this point. The evidence seems very strong, therefor, that the Kelson batholith was intruded in the main during the latter half of the Jurassic revolution or, as Schofield calls it the Jurasside revolution. The Windermere Map Area Apart from a Stock some seven and a half miles by three miles in dimentions that occurs north of Horsethief Creek there is little granite in the area. Lithology; The rock is light-coloured, medium to coarse grained and, in general, porphyritic. The phenocrysts are of pinkish microcline up to an inch and a half in size. It con-sists essentially of microcline, microperthite, sodio plagio-clase and quartz. In other respects it differs little from the granites already described. It is slightly banded in places while some of the smaller dykes and sills are pegmatitic and contain black tourmaline. Metamorphie minerals in the intruded rocks described by Walker are actinolite, diopside, epidote, garnet, vesuvianite and talc and in the limestones, 39 Walker suggests that these granites were intruded as the last phase of the mountain building since he found them cutt-ing already highly folded sediments. He also noted that the apophyses were never deformed. The presence of the pegmatitic phases would suggest the possible relationship to the Nelson Pegmatite-gneiss complex which Gairnes had placed as the last phase of the intrusion of the Nelson batholith. Age and Correlation: Walxer1 has compared this with the FlTalker. J.F.. G.S.C.. Mem. 148 p 101A" 2 stock at Fry Greek east of Kootenay .bake which Bancroft 2~Bancroft. M.F.. G.S.C.. Summ Rpt 1920 p 101A has related to the Nelson batholith. The granite in the Win-dermere area may, therefore, be considered to be of the same epoch as the Nelson batholith but an attempt t o make a closer correlation appears to be inadvisable. POST JUR^bSIC LxiMPhOPHYiul Dl^S Distribution; Dyxes of this character occur sparsely in .I various parts of the area particularly near the town of Ains-worth1 and in the Windermere^ area. n?chofield. S.J.. G.S.C. . Mem 117 .p 23 2 Walker. J.F.. G.S.C.. Mem 143 p 37 Age; The age of these intrusives suggested by ochofield 90 some period later than the Jurassic or early Cretaceous since '•rl&ey contain fragments of the batholithic rocks. On the other vt hand they have "been altered by the mineralizing solutions in the Ainsworth area which would indicate that they were intruded not long after the injection of the batholithic magmas. Lithology; The commonest rock in the Ainsworth area is Gamptonite which Schofield describes. It is a dark grey to brown rock containing phenocrysts of hornblende and biotite, the former being up to three inches in length in places. The rock is also commonly fine grained with a few phenocrysts of plagioclase and hiotite. Apatite and magnetite are quite abundant» Walker found augite in the Windermere area. 2 The Cranbrook Section The Purcell Sills These sills outcrop in various places throughout the Cranbrook Map area wherever the tilted beds of the Purcell series into which they have been intruded have been eroded so as to expose them. The main showing, however, occurs just to the south west of the Town of Cranbrook. Lithology; Speaking of these sills Schofield finds that they range from a hypersthene gabbro to a very acid granite or granophyre, with all intermediate phases. In texture tney vary from fine grained to porphyritic. Three main rock types have yi een recognized by him; a gabbro, a quartz-diorite, and a granite. The Gabbro is the most basic type and is a dark grey, crystalline rock of granitic texture in which plagioclase and augite can be distinguished. A surprising and unusual feature is that the rock is quite fresh. In thin section the essential constituents are found to be labradorite and pyroxene the latter being both hypersthene and augite. Uralitization is common. In table 2 is given an analysis of this rock, ¿is variations from this hypersthene gabbro occurrences of hornblende gabbro are not uncommon. Schofield believes that these are but a metamorphic form of the former. Daly gives an analysis of this that is also given in table * • Within the body of the sill bands of various differentiate occur varying from aplitic and pegmatitic phases to more basic ones occuring as schlieren. The Quartz-diorite is the transitional rock from the gabbro to the granite. It is a light greyish-green rock show-ing quartz, feldspar, hornblende and biotite in the hand speci-men. In thin section labradorite to andesine plagioclase is found to be plentiful while the hornblende lies embedded in a ground mass of quartz and micropegmatite. Chlorite and Zoisite occur as secondary minerals. Daly1 again gives an analysis Daly. R.A. "Festschrift zum siebzigsten Geburtsta&e von H Ros-that is reported in table 2. 92 The Granite usually ooours near the upper contact of the t aills and is a fine-grained, holocrystalline to porphyritic, pinkish granophyre, with biotite, quartz and feldspar as the prominent minerals. In thin section micropegmatite, microper-thite and a plagioclase {probably andesine) can "be distinguish-ed. Magnetite, titaniferous magnetite, apatite and a little garnet also occur. An analysis "by Daly2 for the granophyre ITBaly. B.A.. Am. Jour. Sci. 4th ser Vol 20 1025 p 122 is given in Table 2. Age and Correlation; Daly1, as has already been mentioned ITaly R.A.. G.S.C.. Mem 38 considers these sills to be related to the Purcell lavas and therefor occuring in the top of the Precambrian betv;een the top of the Siyeh and the bottom of the Gateway. With this opinion Schofield2 concurs. FlSchofield. S.J,. G.S.C. Mem 76 Schofield calls attention to the beautiful examples of differentiation that are presented in these sills. He describes two of them, the Moyie and the St. Mary sills in detail4. He 4~lachofield. S.J.. G.S.C.. Mem 76 pp 70-75 points out that the original source of the magma was an inter-crustal reservoir in which differentiation had proceeded to a certain point allowing for magmas of different compositions being drawn off at different points. These, when injected, further differentiated giving the composite sills. He dis-93 oussed it further in a paper on "The origin of Granite in the Puroell Sills"5. 5 Sohofield. S.J.. G.S.C.. Mua Bull Ho 2 p 1 THjl PU'EJ^L LhYA As mentioned the Puroell sills have been related to these flows; it may therefor "be of interest to oonsiaer tnem in a little detail. Schofield finds that the dominent rock of this formation is usually a highly altered amygdaloidal or porphyritic basalt. He finds the flows generally to be very hetrogeneous in char-acter. The amygdaloidal basalt is a dark green to black rock with the amygdules filled with quartz and sometimes nemetite. In the porphyritic phases crystals of labradorite up to la inches in length are set in a grouncL-'mass composed mainly of labradorite and a decomposed hornblende. Alteration is pro-found resulting in the production of secondary hornblende, zoisite and epiaote. J&ly^ gives the analysis (7) given in Table 2. Granite Intrusives Distribution; The exposures of granite are not very extensive in the area occuring as stocks and bosses scattered throughout the district. Litholo,s;.y; Two special occurrences have been described 94 ; The Rykert batholith, and the Bayonne batholith. llttly describes the Rykert granite as a coarse-grained, gneissic rook, varying from light grey in colour to pinkish-grey. Large phenocrysts of alkaline feldspar and sometimes of sodic plag-eoclase are common. The rest of the rock is mainly composed ©f quartz, feldspar and biotite. Pegmatitic phases are common in the apophyses. In thin section the phenocrysts are seen to be chiefly orthoclase and microcline and occasionally oligo-clase while the groundmass is quartz, orthoclase, oligoclase, mierolcline, microperthite, biotite and muscovite with mag-netite, apatite and titanite as accessory minerals. Dynamic metamorphism is common. Daly gives the following analysis (8) for this rock: The Bayonne batnolith appears to be generally more basic, 'it is similar in appearance but phases to a quartz augite diorite in places. Large phenocrysts of orthoclase are common while quartz and plageoclase, microcline and perthite are abun-dant in the groundmass. Biotite and hornblenue both occur. The more basic phases show about equal proportions of orthoclase and plageoclase, the latter characteristically zoned. Horn-blende occurs as a secondary product from augite and still shows the augite as a core to the crystal in places. Titanite and apatite are quite abundant in ideomarphic crystals. The piagioclase varies from andesine to labradorite. Daly gives an analysis of this basic phase. 95 Daly olassea the rook as a basic granodiorite but suggests * that there may be a more acidic phase further north. This Sehofield has been able to confirm. Age and Correlation; Sehofield believes them to be late Jurassic in age since he relates them to the folding that took plaee during that period; direct evidence is not present, how-ever, in the area. Their genetic relationship with the Helson batholith is suggested by the increase both in number and size of the intrusions going westward. The Rykert batholith, occur-ing on the International boundary west of the Kootenay river, has been considered by Daly1 to be late Jurassic but the I~T)aly. R.A.. G.S.C.. Mem 58 p 316 Bayonne batholith, occuring round the south of Kootenay lake, he believes to be Miocene. Further evidence has lead Sehofield2 £ Sehofield. S.J.. G.S.C.. Mem 76 p 84 rfce to place this granite with the rest ofoccurrences in the Cranbrook area in the late Jurassic or early Cretaceous. 3. THE YMIR SBCIIOH This district includes the area between the Kootenay Lake and River and the Columbia river and south of the West .arm of Kootenay Lake to the International Boundary. Distribution; Granites in great profusion have been in-96 into the folded strata of this area and subsequent deep erosion has exposed large areas of them. This is particularly-true to the north where direct connection to the Helson batho-lith can be traced. Granite Porphyry Tongues Drysdale1 records a number of these bodies of igneous rock I""Drysdale. C.W.. G.S.C., Mem 94 p S2 occuring in the Ymir series and suspected that they were genet-ically related to certain of the ore bodies in the region. Lithology; \7hen fresh the rock is green or greenish-grey and generally spotted with crystals of orthoclase up to an inch in length, embedded in a fine-grained groundrnass of quartz and feldspar. Apatite and zircon are also present as accessories. The rock is very generally metamorphosed and sneyred and shows secondary quartz and incipient sericitization of the orthoclase. Hornblende and calcite have also developed as a result of metasomatism. Inclusions of schist have been found in it. Age and Correlation; Drysdale found that the porphyry is intrusive into the members of the Hossland group but that it was cut by the Nelson Granite. He, therefor, concludes that they represent the earliest manifestations of tne Jurasside revolution. He suggests a correlation with the diorite porphyry of Rossland although the tongues are more alkalic. Kelson batholith Drysdale correlated the main na sses of granite intruding 97 the sediments of the Ymir area with the Kelson batholith. He finds that the rock varies tremendously from place to place ranging from a granite to a diorite. Lithology; The rook varies in texture from a fine-grained granodiorite to a coarse porphyritic granite. The porphyritic granite is light grey to pinkish-grey in colour, coarse in grain and with a tendency to produce a well-developed augen or gneis-sic structure. Large phenocrysts of orthoclase and microcline and occasionally of plagioclase are embedded in a groundmass of quartz, orthoclase, microcline, biotite and serecite with accessory magnetite, apatite and titanite. Drysdale relates this porphyritic phase to Daly's^ Rykert granite which has al-ready been described. ITaly. R.A.. G.S.G.. Mem 28 p~284 A commoner rock is, however, a grey granddiorite of medium texture in which orthoclase, plagioclase (chiefly andesine), biotite or hornblende and quartz are extensively developed and microcline, titanite, magnetite, apatite, and zircon are access-ory constituents. Chlorite, epidote, kaolin and limonite are common products of alteration. Drysdale found, connected with these intrusives, many dykes, some of which had the same composition while others varied widely from aplites to lamprophyres. Dynamic metamorphism has had considerable effect in alter-ing the granite and rendering it gneissic. Drysdale concludes 98 from the faot that both gneiss and intruded sohist have the same general strike that the orogenio movements of the Laramide revolution at the end of the Cretaceous had its effect on both. Age; Drysdale ascribes these rocks to the Jurassic period on general evidence. Monzonite Chonolith Distribution; A short distance south west of the town of Ymir occurs the body of rock that Drysdale has called a Monzonite Chonolith. Lithology; It is greenish-grey to black rock with dark pyroxenes scattered among tne light coloured feldspathic con-stituents. Drysdale classes it between an augite-biotite syenite and a normal monzonite. The essential constituents are augite, biotite, orthoclase, and acid plagioclase; with iron ore, apatite, hornblende and quartz as accessory constit-uents. The usual alteration products are present. Age and Correlation; The monzonite appears to be fresher than the Kelson granodiorite showing considerably less the effect of orogenic movement. It is clearly younger than the granite porphyry and yet older than the main period of mineralization and the Salmon River Monzonite and Pulaskite. Drysdale suggests that it is very likely a late phase of the Kelson batholithic invasion and therefor probably late Jurassic or early Tertiary. 99 Drysdale suggests that similar rooks appear in the vicinity of Rossland. The Summit Stocks These bodies of granite are related by Daly1 to the Ba; onne l"~Daly. R.A.. G.S.C.. Mem 38 p 296 batholith to which he believes they are genetically connected. Li til o logy; It is a medium-grained, lignt pinkisn-grey rock witn quartz, micropertaite, ortnoclase, and minor quantit-ies of microcline and oligoclase developed. Biotite, titanite, magnetite, apatite, and zircon are sparingly present. Primary muscovite is intergrown with biotite. Daly found evidence of absorbtion along the contact, together with a vast amount of included fragments. The conglomerates especially show abundant evidence of having been partially absorbed. He found that the cementing material showed all stages of alteration to complete replacement by granite. He also suggests that the mus-covite may be formed from the serecite and feldspar of the countx4y rock. With these stocks Daly connects a number of small irregular intrusives having the form of an Appophysis of quartz aiorite. The difference in mineralogical composition from the parent magma is rather striking. The dominant feldspar is and-esine occuring as idiomorphic crystals. addition to this quartz and biotite are also important. Titanite, magnetite, 100 ziroon and musoovite are common accessories. Ho trace of alkali feldspar was found, Age and Correlation; Daly "believes that "both types of rocks are connected with the Bayonne batholith which is bel-ieved to be a part of the Kelson batholith by Schofieldl and nTchofield. S.J.. G.S.C.. Mem 7b p 84 therefor late Jurassic in age. Daly further believes, from the intensity and size of the metamorphic aureol surrounding the stocks that the main mass of the granite cannot be very far below. The Lost Creek Body This body of granite, too, Daly connects with the Bayonne l~"Daly, R.A.. G.S.C.. Mem 38 p 302 batholith through the medium of the Summit stocks on minera-logical and lithological evidence. Lithology; The rock is quite alkaline with microperthite and orthoclase as the dominant feldspar. Oligoclase is present in subordinate amounts together with other accessory minerals as in the Summit stocks. The Bunker Hill Stock This body of granite lies to the south of the Town of Salmo and was correlated, on lithological grounds, with the 101 smaller Summit Stocks and the lost creek body since the min-eralogical composition is very similar. The granite has, however, a distinctly gneissic texture and, near the contact is distinctly more basic and resembles the quartz dioritic phase. Main Kelson Batholith The rocks underlying the Kootenay river from Kootenay Lake to Arrow Lake are of the southern edge of the Nelson batholith, from which many tongues and genetically connected stocks and bosses intrude the sediments to the south. This p portion of the batholith has been described by LeRoy as vary-2 LeRoy. 0.33». G.S.C.. Guide Book No 9 p 61 ing from a light grey granite to a dark grey quartz diorite or even to a more basic type. In places he found porphyritic typ' with feldspar phenocrysts from' 1 to 2 inches in length. LeRoy gives the following as a typical analysis (10) of the Nelson Granite;-The Salmon reiver Monzonite Both Daly and Drysdale1 found stocks of coarsely granular 1 Drysdale. C.W., G.S.C.. Mem 94 p ¿8 monzonite occuring in the area. These Drysdale has correlated to the Coryell batholith of the Rossland Map Area and consid-eration of them will be deferred until that area is described. 102 4 The Rossland Section The igneous rocks of this area are but a continuation of the rocks found in the Yrair district to the east. Granitic igneous bodies of considerable size are common throughout the area and represent a very considerable range in time of in-trusion. They vary in size from comparatively small stocks to the intruslves of batholithic dimentions such as the Coryell and Trail batholiths. The Trail Bathoiith Distribution; The Trail bathoiith occupies an area surr-ounding the Town of Trail on the Columbia river and is about ten miles long and rather less than tnat in width. There is little reason to doubt that it is an offshoot of the Kelson bathoiith and both Daly1 and Drysdale2 think that the entire 1 Daly. R. A.. G.S.C.. Mem '¿8 p ¿46 2 Drysdale. C.W.. G.S.C.. Mem 77 p 212 area is unuerlain by granite of the Nelson batnolith and at no very great depth. Lithology; The granodiorite of the Trail bathoiith is a greyish, granular, crystalline rock varying from medium grained to coarse grained and oomposed of plagioclase and orthoclase, biotite,hornblende, and small quantities of quartz. Gneissic structure is common and is an evidence of the stress which the 103 5*0ok has been subjected. In thin section the plagioclase is 8? j •found to be an acid labradorite to a basic andesine, the latter being frequently zoned. Quartz, biotite, and hornblende are also essential constituents. Common accessories are magnetite, apatite, and titanite. Bpidote is commonly developed as a secondary mineral. Daly gives the following (11) analysis of a typical specimen of the granodiorite and (12) is from a specimen of Drysdale's; Tahle 2. Daly found more acid phases grading to a biotite or horn-blende granite, in which the feldspar is mainly orthoclase. Daly also records the fact that the a outheastern contact of the batholith exhibits a zone of pronounced shattering. Age and Correlation: There is little doubt that this body of granite rocks is a part of the main Kelson batholith to which Daly, McConnell, and Brock have all assigned the age of late Jurassic. Diorite Porphyrite Tongues Distribution; Drysdale describes this as a border and dyke phase of the Trail batholith. They are particularly well developed north of the Town of Rossland. Lithology; They range in colour from light grey to dark greenish-black and are composed of hornblende, pyroxene and feldspar crystals in a fine, crystalling groundmass. There is a considerable amount of variation the end products being a 104 hornblendic phase and a feldspathic phase. The hornblende is developed as fine aoioular crystals a twentieth of an inch in length. In thin section Drysdale found the rock to contain plagioclase, from andesine to acid labradorite (considerably zon-ed, hornblende and pyroxene in a fine groundmass of feldspar, quartz and hornblende. Drysdale notices that the Diorite porphyrite is developed chiefly where the batholith and" its offshoots are in contact with the augite porphyrite of the Rossland group. The question arises as to the possibility of assimilation of the intruded rooks by the invading magma naving effected its composition. Drysdale1 gives the following analysis (13) of a specimen of n>ryadale. G.>/.. G.5.C.. Mem 77 p 26 the diorite porphyrite. Age and Correlation; DZ^sdale believes that the diorite porphyrite is closely related to the main intrusion but considers that it is, in all probability, slightly oluer than the grano-diorite of the main body which stopes it out in places. It is, however, referred to the late Jurassic. The Andecite Flows and Pyroclastics Distribution; Tnis formation is sparingly developed on Mount Roberts. Lithology; Drysdale describes it as a holocrystalline, porphyritic, aphaenitic dark greenish-grey rock. In thin 105 section it shows hornblende and pla^ioclase (labradorite and andesine) as phenocrysts and small amounts of magnetite and orthoclase. The groundless is composed of a felted mass of the same minerals with a trachytic structure. The hornblende is considerably altered to chlorite. The tuff beds are dark, dense and well stratified with in-tercalated flows of andesite. Age and Correlation; Drysdale believes these t o be the extrusive equivallent of the granodiorite on account of there lithological similarity and tnere stratigraphic position. They may, therefor, be consiuered to be late Jurassic in age. The Rossland Honzonite Distribution; The main exposure of this rock occurs in a large Chonolith, oval in shape, having an east-west elongation of about five miles and a maximum width of about one and a half miles. The town of Rossland is situated on it near its west-ern margin. Drysdale remarks on the similarity of some stocks oocuring in the Ymir region a description of which have already been given. Lithology; A study of these rocks was made in 1906 by R. '.7. Brock and G. A. Young the results of v/nicn were never published. A large portion of the manuscript of Dr. Young has been quoted by Daly1 and again by Drysdale2. He describes tne 106 I~Daly, K.A.. G.S.C., Mem 5d p ¿58 £ Dryadale. C.W.. G.S.C.. Mem 77 p 191 et seg. rock as being a generally eoarse-grainea monzonite very variable in composition and texture in different parts. The coarse phase is usually dark in colour and consists of dark pyroxene and sec-ondary hornblende, biotite, and feldspar. The augite and horn-blende often forms the bulk of the rock. The feldspar is al-most always plagioclase and usually labradorite. A bonded structure is sometimes present in which the feldspars are al-most absent. In some puases of the monzonite alkali feldspars are quite abundant. Tne following analysis (14) snow the char-acter of the rock and with it is given an analysis (15) showing an average of four of the augite latite flows. The correspon-dence between the two is most significant. Daly points out tntt the increase in silica in the extrusive ia typical. Young, as quoted by Drysdale, suggests that the Chonolith in 107 question represents tne top of a much larger body that has not been unroofed as yet. Drysdale believes it to be a part of the main Nelson batholith and may therefor represent a portion of the top of that vast intrusive where it has not been deeply disected nor even entirely unroofed. In this connection it is interesting to note the differentiation that hus apparently been in progress and the consequent changes in composition ana tex-ture. Young can offer no explanation for the metnod of entry of the body nor could he see any evidence of absorption of material by the monzonite. Drysdale believes that the monzonite is late Jurassic and represents a late phase in the intrusiOB of the Nelson batholith. Augite Latite flows Distribution; The augite latite was found by Daly at wide-ly spaced localities in the area. Lithology; When fresh Daly1 detoribes the rode as a deep 1 Daly, R.a.» G.S.C., Mem 38 pp ¿¿¿-¿£6 greenish-grey to almost bl&ck rock with abundant pnenocrysts of plagioclase and pyroxene. Very little alteration is present. The plagioclase varies from labraaorite to bytownite. Zones taking the form of an orthoclase rim to the plagioclase crystals are not uncomnon. The pyroxene is usually green augite. The groundmass is usually more altered, uralitization beine present; chlorite, biotite and serecite are also usually present. Shreds 108 rf -Î of glass with microlites can be seen in the thin section. The following is an analysis (16) of this rock. Metamorphism has, nowever, profoundly altered the rock in many places transforming it into a massive green rock showing porphyritic character only by the presence of broken and alter-ed feldspar phenocrysts. Apart from tnis complete reconstitu-tion of the rock has taken place with the production of epiaote, calcite, quartz, chalcedony chlorite, biotite, amphibole (ura-lite and actinolite), zoisite, pyrite, etc. Age and Correlation; Since the augite latite always appears above the andesite flows and tuffs in the section, it is felt to be younger than them and also than the diorite porphyrite. Its similarity in composition with the monzonite has lead Drysdale to class it with tne Monzonite and probably a very late phase in the intrusions accompanying the Jurasside revolution. The Porphyritic Monzonite Stocks Distribut ion; These stocks are quite common in the area to the west of Rossland. Lithology; Young, as quoted by Drysdale, remarks on the fact that the rock in any one body shows little variation. Typically it is a light grey coarse-grained rock and composed of dark green pyroxene and secondary hornblende, biotite and feldspar. I n thin sections the feldspar is seen to be tne alk-ali variety frequently twinned with plagioclase. Piagioclase 109 a common "being more finely crystalline and is composed of and-f * ij esene. In a few places "biotite is developed at the expense of the pyroxene with the plagioclase approaching the composition of acid labradorite; the alkali feldspar being less abundant. Age and Correlation; Young believes that the porphyritic monzonite is younger tnan the monzonite although definite proof of this is not forthcoming. Drysdale1 also suggests that it is older than the Nelson granodiorite. In the vicinity of Sneep I^rysdale. C.W.. G.S.C.. Mem 77 p 235 Creek, dyke-like masses of the porphyritic monzonite seem to have intruded into the granodiorite. Young points out that the porphyritic monzonite and the monzonite are mineralized very similarly and hence suggests a close relationship between the two. He believes that the porphyritic type may be a later phase of the monzonitic invasion. Drysdale also points out that cer-tain contact facies of the Coryell batholith are monzonites and suggests that the porphyritic monzonites may be genetically connected with them. A stock of porphyritic monzonite near Ymir has a core of pul^askite very similar to that of the Coryell batholith. Drysdale also points out the pipe-like nature of the out-crops and suggests the possibility of their being old volcanic necks. Drysdale places them tentatively in the Oligocene. 110 Sheep Greek Dlorite Porphyrite Distribution; This consists of a large dyke cutting the grano-diorite and the porphyritic monzonite that occurs on the west side of Sheep Greek a mile west of the town of Rossland. Lithology; This rock differs from the diorite porphyrite mentioned earlier and is a pink porphyritic rock with pheno-crysts of feldspar with the crystals up to an inch in length, and with them quartz. In thin section the dyke is found to be composed of plagioclase, quartz, and highly altered augite in a fine groundmass of plagioclase, orthoclase and quartz. The dyke shows aphenitic borders where the rock becomes lamprophyric. This phase consists of a mosaic of plagioclase, biotite, augite and quartz. Age; Young suggests that it may represent a late phase of granodiorite but Drysdale, from the fact that it cuts the por-phyritic monzonite, places it tentatively in the Oligocene. The Salmon River Monzonite Distribution; A very interesting occurrence is that of a stock described by Drysdale1 as the Salmon River monzonite. l~Dryadale. C.W.. G.S.G.. Mem 94 p «¿8 It occurs about a mile south of the town of Ymir. Lithology; It consists mainly of a coarse grey rock con-taining augite and biotite in a matrix of feldspar. In thin section the augite is found to be diopside; sodic orthoclase 111 and labradorite eompriae the feldspar. Apatite and magnetite are the main accessories. A typical specimen from a similar stocic was collected by Daly2 and the result of the assay is 2 Daly. R.A.. G.S.J.. Mem 38 p 305 given in the table below. "7aWe The most interesting feature of the occurrence is the fact that the core of the body is composed of a typical granular pulaskite almost identical with that of the Coryell batholith. Drysdale believes that the Salmon river stock is an eroded core of an old volcanic conduit, and that the central core of pula-skite represents the last stage of vulcanism. Any acidic flows that may have been produced have been entirely eroded off. Age and Correlation; Drysdale, on the evidence of the pulaskite core, suggests that the Salmon river monzonite may be correlated with the boruer phase of the Coryell batholith. He has considered them to be Oligocene, but no definite evidence ia forthcoming. The Coryell Satixolith Distribution; G. A. Young, as quoted by urysuale, believes this to be one of the youngest igneous rocks occuring in the area. The main development takes tne form of a batholith some ten miles in diameter occupying the greater part of the area between Rossland and Christina lake, A number of uykes and apophyses cut the older formations in the vicinity of Rossland. 112 Lithology; The rock is characteristically a pulaskite or alkali syenite. It is typically a medium to coarse grained, occasionally porphyritic rock, the feldspars running up to two inches in length. Young notes tne rapid variation nortn in texture and composition within short spaces. The rock is us-ually fresh and reddish to pinkish-brown in colour. Hornblende and biotite are the cnief femic constituents ana the preaomin-ent feldspar is a coarse intergrowth of orthoclase and albite. The following table^gives 17, an analysis of a typical specimen collected by Brock and 18, the analysis of the more basic, contact phase, and 19, an analysis of the Salmon River monzonite collected by Daly. Along the southern contact Daly found a well-developed basic phase which contained a large amount of hornblende, dio-pside and biotite. Andesine was the prevailing feldspar and is accompanied by orthoclase and microperthite. The accessories are apatite, magnetite and titanite. Age and Correlation; Drysdale, quoting from Young, says "The palaskite seems to represent one of tne last igneous in-trusives within the area of the camp (Rossland). The syenite distinctly cuts all other types of rocks with the exception of the Sheppard granite porphyry and certain of the lamprophyre dykes and the latter seldom cut the syenite in spite of the fact that they are so numerous in the district." Brock and McConnell1 decided that the rock was Tertiary and Drysdale has 113 h I~*G.S.C.. V7est Kootenay Sheet. Map No 792 placed it tentatively in the Miocene on the strength of the 11-thological similarity to Miocene intrusives in the Boundary district described by LeRoy2, the Coryell batnolith and the 1T"LeRo.y, 0.3. . G.S.C.. Mem 21 pp 49-52 Salmon river monzonite and through them, possibly, to the Rossland Monzonite. The Sheppard Granite Distribution; Just to the '«vest of tne town of Rossland a number of dykes of pinkish to ^rey granite cut both the grano-diorite and the Pulaskite. Two larger bodies, taking the form of stocks, have been mapped by Daly to which Drysdale has corr-elated these dykes. These occur one on the boundary just to the west of the Columbia river and the otner a little to the north of this and just south of the soutn end of the Trail batholith. Lithology; It is composed of quartz, micropertnite, orthoclase, and oligoclase, hornblende and a little biotite. It is generally porphyritic, the phenocrysts generally being acid plagioclase and the groundmass quartz and orthoclase. The following three analyses (20), (21), (22) are of different phases of the Sheppard granite. Table 2. Age and Correlation; Daly1 observed the Sheppard granite 1 Daly, R.A., G.S.C., Mem 38 p~355 clearly cutting the Pend D*Oreille schists, the Rossland Vol-114 canics, the Trail granodiorite and the lake Mountain conglomer-ate and also noted that it is quite uncrushed. This is the more striking in view of the fact that one stock occurs within a very short distance of the shatter zone of the Trail batholith, suggesting that it was intruded after the relief of the stress that occasioned that phenominon. While there is a strong res-emblence between this rock and phases of the Trail batholith, in view of the evident time gap, a close relationship between the two appears unlikely. Daly suggests that it may repr us ent a similar stage in the differentiation of a batholith that is not exposed in the area. Drysdale correlates the granite porphyry with Daly's Sheppard granite on lithological resemblence and suggests that it may represent an apiitic differentiate of the Coryell syenite. He considers the rock to be an apiitic, alk-aline biotite granite and has placed it tentatively in the miocene. Lamprophyre Dykes Distribution; The whole Rossland area is noted for its profusion of lamprophyre dykes of all varieties and tnis fact is, as far as is known, true of the whole area. Lithology; These dykes are generally very dark grey or green and fine-grained but distinctly holocrystalline. They are frequently porphyritic. Young found dykes that could be classed as typical minettes, kersantites, spessartites and 115 vogesites and may intermediate types. Besides these a more aoid group of rocks was also present. Age and Correlation; It has not been possible to distin-guish the various ages of the different types. From the fact that they cut everything and preserve a very uniform character throughout the area suggests a comparatively recent age for them as a group. Drysaale suggests that the sub-alkalic var-ieties, (kersantite and spessartite) may be genetically related to the Nelson granodiorite; the intermediate varieties ¡to the 'monzonites and the alkalic varieties (minette and vogesite) to the Coryell syenite and pulaskite. 5 THE BOUNDARY SECTION Quartz Porphyrite Distribution; This "occurs as irregular dykes and small masses intrusive into the cherts and jasperiods of the Knob Hill group, and in the limestones and lime silicate zone of the Brooklyn formation,"1 l*~LeHo,y, O.E., G.S.C.. Mem 19 p 19 in the De&dwood area. Lithology; The rock consists of phenocrysts of feldspar and amphibole in a groundmass consisting mostly of quartz. In thin section plagioclase is seen and the amphibole appears to be actinolite. The groundmass is quartz and feldspar and a 116 iittle oaloite. Age and Correlation: LeRoy believes these to "be post-Brooklyn and pre-Jurassio and has placed them provisionally in the upper Paleozoic. If we accept the iaea that the Brooklyn formation is Triassic they must have been intruded at the close of this period. The Cascade Batholith Distribution; Daly1, in the course of his survey of the 1 Daly. R.A.. G.S.C.. Mem 38 p 379 International Boundary re-examined the area of rocxs mapped by Brock and McConnell2 as Archean crystalline schists and believes 2 G.S.C. ;/est Kootena.y Sheet Map 792 it to be an intrusive body of relatively old gneissic granite. This formation lies between Christina Lake at the Town of Cas-cade and Grand Forks and forms a belt along the Boundary. Lithology; Daly describes this rock as being intensly crushed and foliated to a high degree. He found the least al-tered specimen he came across to be a light grey, medium-grained gneissic rock in which he recognized, quartz, feldspar, and biotite; with small amounts of apatite, magnetite, titanite and zircon as accessories. He believed the original rock to have been a biotite granite. The greater part of the feldspar was plagioclase (andesine and labradorite) but orthoclase was also quite abundant. rock has a highly handed structure which Daly describes in some detail. The bands differ in both minera-117 logical and chemical composition from each other and from the fresher phases of the rock. The darker bands show a marked in-crease in plagioclase and femie minerals over the lighter ones. Daly suggests that they may have been caused by the leaching out of the more basic minerals and their deposition along def-inite bands. Cairnes3 explanation of the banking in the Nelson 3 Gairnes. J.H.. G.S.O.. Summ Rpt 1928 pp 1U3-104 ^ Pegmatite complex is of interest hexe and suggests the possib-ility that there may be a relationship between it and Daly's Cascade Gnaess. Age and Correlation: No very definite age can be assigned to this rock but Daly believes that he found related dykes and stocks cutting the traps of the Rossland group and the Suther-land schist. This would put it at least as young as the top of the Triassic and the degree of foliation and crushing would suggest that it was intruded early in the Jurassic revolution and that it had been subjected to the major part of the oro-genic movements that accompanied that period of mountain build-ing. The Nelson Batholith Distribution: While the northern boundary of the area is formed by the Nelson batholitn and LeRoy believes that the greater part of the area may be underlain by it actual expos-ures are limited to a number of relutively small stocks and 118 similar intrusives. These are, however, distributed at ran-dom all over the district. Lithology; LeRoy describes the rock as a light grey biotite hornblende granodiorite with associated granite porphy-ries, quartz diorite, porphyries and monzonites. The texture ranges from granitoid to porphyritic. The rock consists ess-entially of feldspar, hornblende, and quartz, .apatite and magnetite are also present. The feldspar is found to range from ortiioclase to acid labradorite. LeRoy also found a more basic phase ranging from a hornblende gabbro-like rock to pure hornblende rocks which he believes belong to the same general period of intrusion. In the Phoenix area LeRoy1 found a small mass of augite r~LeRoy. O.iS. . G.S.C.. Mem 21 p 41 porphyrite which he reletes to tne same general period. It is a dark grey, granitoid rock consisting of feldspar and pyroxene. In thin section it is founa to contain orthoclase and pla£jio-clase, augite, biotite, quartz and magnetite. A considerable degree of alteration has taken place. Age and Correlation; The syenite was found to cut the Triassic Brooklyn and Knob Hill formations and the whole series was correlated with the Nelson batholith on this lithological similarity. They may, therefor, be assumed to be Jurassic in age. 119 Augite Porphyrite Distribution; Thia rock occurs as dykes and sills and stocks cutting all the formations of the area including the Midway volcanics. Lithology; The rock is dark grey in colour and consists of phenocrysts of dark grey feldspar, brown to black pyroxene and hornblende and biotite. In thin section tne feldspar is found to be predominently plageoclase (andesine to labr^aorite) although some orthoclase is present. Tne base is largely fela-spathic with minor amounts of quartz, magnetite and apatite. No. Z'6 Table 2 is an analysis of the augite porpuyrite :-Age and Correlation; ./hile tnese rocks have been fo und to be intrusive into the members of the Midway Volcanics there petrographic similarity with those lavas suggests that they be a late phase of that period of volcanic activity. They have therefor been placed in the Miocene. Pulaskite Porphyry Distribution; This rock occurs as dykes and sills quite widely developed over the whole area. Some of them having a very considerable thickness. Lithology; It is grey in colour and consists of pheno-crysts of feldspar in a fine groundmass also mainly of feld-spar. In thin section the phenocrysts are s een to be plagioc-lase (oligoclase to acia andesine) and anorthoclase. Small 120 amounts of augite, "biotite, quart-z, magnetite, apatite and chlorite make up the balance of the rock. Leiioy suspects the presence of some feldspathoid which has been obscured by alter-ation. A related rock described by LeRoy^" is the monzonite por-1 LeRoy. O.E.. G.S.G.. Mem 19 p £9 phyry, found in the Deadwood area. No. 24 is a chemical analysis of a specimen of this rock collected by LeRoy. No. 25 is an analysis of a specimen collected by Daly2. 2 Daly. R.A.. G.S.C.. Mem 38 p 419 Age and Correlation; LeRoy felt that the igneous rocks of the area were all intemately related and probably had a common source and were intruded during the same general period of activity although that may have been spreaa over a vast time interval if counted in years. There appears to be a reasonable correlation between the pulaskite porphyries of the Coryell batholith and it would appear reasonable to assui.ie a Miocene age for the former. In connection with the igneous rocks of the area it may be of interest to include Daly's tentative table giving tne order of succession of lavas and their related intrusive rocks 121 Lavaa Intrusive rocks ( Analicite lava ) Rhomb porphyry ( ) Youngest group { Extrusive Rhomb-porphyry ) ( Alkaline trachyte Pulaskite porphyry Middle group ( Biotite andesite ( ( Biotite-augite-andesite ( Hornblende-biotite-augite andesite ( Hornblende-augite andesite -*ugite-x>iotite por-phyrite Oldest group ( ( Augite andesite ( Olivine basalt ( Augite porphyrite Augite gf bbro 122 Summary of the Igneous Activity Precambrian The earliest record of igneous activity in the area is that left by the Purcell lavas and sills of the lower Pareell time. These Precambrian igneous rocks were mainly ex-trusive in character although they were generally accompanied by the intrusion of a number of very large sills. They occur in the Cranbrook Section and are particularly well developed round Moyie. The chief interest in them lies in the differ-entiation Schfield observed and also in the mineralization that appears to be directly associated with them. Apart from these no igneous rocks are definitely known until the extrusion of the Irene Volcanics during the last series of the Precambrian. These, too, are of purely local development, being found only in the Ymir Section, their equivalents not being known in strata of the same age further north. Traissic Volcanic Activity The record of the Paleozoic is practically confined to the Windermere and no igneous activity of that age is re-corded there or elsewhere. Very soon after the commencement of the Mesozoic, in the early Triassic, we have evidence of the tremendous outburst of volcanic activity that has made the strata of that period in British Columbia as widespread and long continued a record of such activity as any in the world. 123 It may be of interest to mention, in this connection, that Baddington and Chapin^record volcanic rocks in southeastern 1. Buddington, A.F., & Chapin, T. U.3.G.S., Ball 800 p 43' Alaska during the following periods:-Lower and Middle Ordovician, Middle and Upper Devonian, Lower Permian, Upper Triassie, Jurassic, Lower Cretaceous, Eocene, Pliocene, Quaternary. In the Britannia Map Area at the Coast, the writer has seen several thousand feet of Triassie tuffs and volcanic breccias practically unbroicen in a stratigraphic column. No other instances need be mentioned, although they are present in abundance, to show the widespread igneous activity nor the great quantity of extrusives in this part of Worth America. To return to the district being discussed, it is not wj?[iOfcanH. rocks, of Hi£-Tfi'ass/'cper/odare as w/i/eifrstrdas /¿ereoorc/j surprising, in view of this, that the recordsAof the sedimen-tation of any period. They occur in the Lardeau, Kootenay lake, and Slocan Map areas and in the Ymir, Rossland and Boundary sections. Two of the remaining three sections have had all Mesozoic rocks eroded away so that there, too, these rocks were probably laid down. 124 Immediately following, and probably overlapping, this period of vulcanism, comes the period of Platonic activ-ity represented by the Major granitic, intrusives that are so important a feature of the area. The connection between the two is not clear if it exists at all although the inception of the Jurasside revolu-tion may have caused the opening of the channels for the egress of the Triassic eruptives and may later have developed the tremendous compressive forces that swept the strata of the .geosynclinal basin or basins into the major folds where the Columbia mountain System now exists. Whatever the connection between the Triassic and Jurassic igneous rocks there is no doubt that the tremendous orogenic forces of the late Jurassic produced a differential stress that permitted the ingress of the granitic rocks forming the various batholiths of the area and their related bodies. The whole theory of batholithic invasion is in a very uncertain condition and, with the limited information at the writer's command regarding the area, a discussion of it here would be entirely out of place. A few facts have, how-ever, been brought out that are worth recording. Daly favours the theory of magmatie stopping. A full discussion by him of both this and other theories, will be found in The Mem 38 Part 11 of the Geol., Sur., Can., pp725-767 and in papers by Daly in the American Journal of Science for 1903 and 1908. To these the reader is referred. The 125 theory of magmatic stopping presents a good deal of difficulty to the writer and leaves a great many unanswered questions. Among these is the apparent orientation of "floating clocks", and the immense number of inclusions of all sizes held in sus-pension at all distances from the actual contact. Cairnes^believes that his Pegmatite-gneiss complex is T7"Cairnes, U.fl., G.S.C., Summ Bpt 1928 pp 103A a part of the Kelson batholith and yet finds the sedimentary rocks gradin- into it by alteration imperceptably. Hot only this but he finds a common alignment of bedding ana banding and further can trace some Deds back into bands in the true gneiss. With regard to the Rossland Monzonite Chonolith Young, as quoted by Drysaale, could offer no explaination for its mode of entry nor could he see the least evidence of ass-imilation. The whole period of intrusion lasted at intervals from the Jurassic up to the Miocene. The following is a list of the major igneous bodies that have been discussed in the bo-dy of this chapter:-Jurasslc 1. Nelson batholith, a. Nelson gabbro-gneiss, b. Helson granite, c. Nelson Pegmatite-gneiss complex, d. Rykert batholith, e. Bayonne bauholith, 126 2. Trail batholith, 3. Cascade gneiss, 4. Rossland monzonite, 5. Kuskanax batholith, Oligocene 1. Salmon River monzonite, 2. Porphyritic monzonite. Miocene 1. Coryell batholith, 2. Pulaskite, porphyrits, 3. Sheppard granite, The composite nature of the ¿Vest Kootenay oatholith, taken as a whole, is clearly inaicted by this list of intrus-ives which range in age from Jurassic to Miocene and in comp-osition from alkali syenite through granite to monzonite; not taking into account the different.ites if each as shown in the minor related intrusives. An effort was made to classify these rocks from their compositions but proved of little help. The wide variation in the composition of any single body and the scanty informat-ion making it impossible to pidgeon-hole any of them. It will be seen, however, that there are two dist-inct stages or periods of plutonic activity, one in the Jur^a-ssic and one in the early and middle Tertiary. The former were the hyproducts of the Jurassic revolution and the latter probably of the Laramide. They consist, broadly, of the following classes of rocks. , _ 127 1. Jurassic; a. Gabbro gneiss, b. Granite, c. Syenite, d. Pegmatite, e • Granite porphyry, f. Monzonite, g. Diorite porphrite h. Andesite, i. Augite latite, j. Lamp rp$iy re s, 2. Tertiary a. Monzonite, b. Alkali syenite, - pulaskite, c. Pulaskite porphyry, d. Granite, e. Lamprophyres, The only generalization that is apparent is that the younger group is considerably the more alkaline of the two. Apart from this, the wide divergance of composition of the members of each group suggests a large and deep seated source from which the various types differentiated. There would seem little doubt as to the common origin, an origin that may even have been common to both groups, since the general locus of the occurances is confined to a limited area. 128 SJW Another fact that seems more than likely is that at some stage or stages in the differentiation, possibly differ-ent at different points in the area, there was an escape min-eralizers and the ore-deposits were formed from their passage through suitable openings. One other fact is worth noting and that is that Drysdale believes one of the Salmon River stocks to represent the plug in an old volcanic neck. All trace of any related extrusives have since been eroded away. The pul-askite core of the plug would represent the last stage of vul-*eanism and seems to be related to the alkali syenite group of plutonic rocks an example of which is the Coryell batholith. With the prolific intrusion of the lamprophyre dykes that closed the Tertiary igneous activity the igneous history was also closed for the area. From then to the present time no record is preserved of further rock formation, either ig-neous or, if Yie except the recent glacial drift and as yet un-consolidated deposits, of sedimentry origin. ECONOMIC GEOLOGY Introduction; It is, of course, the economic min-eralization that first attracted attention to the district and since that time, the general geological work done has been with the economic side well to the front. Not much generalization is yet possible, however, although some interesting facts have been brought out. Without further preamble the economic geology of the various map areas will now be considered, and in a summary at 129 the end the various general facts brought out, and som§ con-clusions attempted. Windermere Map Area General Geology; The Windermere Map area lies some thirty miles to the Northeast of the main Nelson batholith. The entire area, with the exception of a strip to the east of Windermere lake and a small synclinal basin in the north, is underlain by Precambrian (Beltian) rocks. These include mem-bers of the upper Purcells overlain by the Windermere series with a marked unconformity between the two. In the two port-ions mentioned, Paleozoic formations are laid down which in-clude all the periods from the Cambrian to the Devonian. The whole area is roughly anticlinal with the axis of the anticline running in a north-south direction up the western half of the area. The Paleozoic rocks east of Wind-ermere lake represent the youngest members of the eastern limb that have elsewhere been eroded away. Rocks allied to the Nelson batholith are not common only being represented by two stocks. Economic Geology; The production of mineral has been very limited in the area, only one property being a steady producer; the Paradise Mine. All the mineral occurences worth mentioning are in the members of the Purcell series and mainly in the limestones and calcareous slates of the Mount Nelson formation. They 130 occur in a zone some ten miles in diameter roughly equidistant from the two stocks. It is interesting to note that this zone is also the one of greatest faulting shown on the map. The occurences are all of lead-silver and lead-silver-ainc and are essentially fissure and bed vein types.^ The gen-ITWalker, J.F. G.S.C., Mem 148 p 43 eral strike of the veins is parallel to that of the folding, -If 30 W. Walker suggests that the relative competency of the beds has played a large part in the location of the veins, only "those oeing mineralized which fractured under the cjnuitions of folding imposed upon them. Mineralization; The metallic minerals occuring are, galena, greatly predominating, with pyrite, small quantities of sj^alerite and tetrahedrite or freibergite as the main silver bearing mineral, in a gangue of quartz & barite; calcite and siderite are present in subordinate amounts. The quartz appea-rs to be of two generations the earlier one varying from vitr-eous to milky and the later one all milky. Walker finds the order of deposition to be; - gangue, pyrite, sphalerite, tetra-hedrite, and galena. Considerable variations were found from this order. Walker oelieves that the zinc content of silver-lead-zinc deposits increases with depth throughout the Cord-illera. THE LARDEAU MAP AREA1 ITvJaiker. J.J'., & Bancroft, M.i?'.» G.S.u.,Mem lbl General Geology; 131 The area lies immediately to the northeast of the margin of the zone of batholithic intrusion and to the west of the Windermere. It is therefor closer to the belt of plutonic igneous activity. It is underlain predominently by rocks of late Windermere age and are therefor among the young-est Precambrian (Beltian) rocks known in British Columbia. They form a broad geosynclinal basin trending northwest-south-east within which minor folding has proceeded to a marked de-gree giving higher dips and considerable contortions every-where. Overlying this area a few patches of Paleozoic and Mesozoic sediments whose most extensive development is along the south east edge of the Kuskanax batholith. The area is bounded on at least two sides by exten-sive granite intrusives which have resisted erosion until they stand out as a ring of mountains. The northern and northwest-ern masses are members of the Nelson batholith classed by Cairnes^as the Nelson granite and the Nelson pegmatite-geiss TTcairnes, C.E., G.S.C., Summ Rpt r§Z& oomplex. The southwest of the syncline is bounded Dy the gra-nitic mass called by Cairnes the Kuskanax batholith. Economic Geology; Gunning^recognized seven different IT Gunning, H.C..G.S.C., Mem 161 p 20 et seq., types of ore deposits. 1. Contact me tarnorohic, deposits, 2. High temperature veins, 3. Gold-quartz veins, 132 4. Silver-lead-zinc veins, 5. Galena-sphalerite replacement deposits in limestone, 6. Quartz tetrahedrite veins, 7. Silver-lead veins in limestone. Mineralization; 1, The contact metamorphic deposits form a small and unimportant group and are of value mainly as evidence for the better understanding of the geaesis of the mineralization of the district. The intrusives responsible for the metamorphism are -granites or related dyke rocks which cut greenstones, banded sediments or limestones. The minerals developed are pyrrhotite, ch^lcooyrite, sphalerite and galena and have never proved of commercial importance. 2. High temperature fissure vein^fs are commonly dev-eloped over the area but have never provea to be of much ec-onomic importance. The mineral association is commonly pyrite, molybd-enite, arsenopyrite, pyrrhotite, sphalerite, ana galena in a a gangue of quartz, tourmaline, calcite, muscovite^albite, and epidote. The wall rocks appear to have little influence on the vein since it cuts indiscriminately, mica schists, quart-zites and a dyke of quartz gatbro diorite; a considerable amount of wall rock alteratijn has gone on however. The relation of these veins to any intrusive is not 133 0 0 clear. They have a general N 30 - 55 W Strike. 3. An economically important group of veins is that oarrying gold in a quartz gangue. The deposits occur in two zones on the same general strike running northwest down the axis of the synclinal basin of precembrian rocks. Gunning found a marked similarity in the different deposits. They are all quartz veins cutting the formations at various angles but predominently paralleling the structures. Silicification of the wall rock has proceeded but alteration is not as severe as in the preceeding case. The mineralization is typically free gold in pyrite, arsenopyrite is common ana often carries good values. Pyrr-hotite, galena, and spalerite are occasionally present. Quartz stringers cutting the country rock may often carry values. The veins have a general Northwest strike although some Northeast ones are known. Gunning puts these deposits in the same class as 1 1 Lindgren^s Mesothermal Deposits. These he defines as "Metal-T7"Llndgren. ¥., "Mineral Deposits 1928" p 598 et secf. liierous deposits formed at intermediate temperatures by ascending thermal watjfiers and in genetic connection with in-trusive rocks." 4. The silver-lead-zinc veins have proved of economic importance in the area. They appear to grade from the gold quartz veins of the previous section. They appear to follow small shear zones cutting the slates, schists and quartzites 134 of the Precambrian rocks at low angles. The vsins are of the true fissure type but replacement of the country rocK has played an important part. The gangue is quartz and ankerite. Some silicification ana serecitization of the wall rock has gone on and where greenstone dkyes have been cut they have i been extensively carbonated. The or^minerals are pyrite, sphalerite, galena, freibergite, and small amounts of chalcopyrite. Gold is com-monly associated with the pyrite. Great variation is found in the silver content of the tetrahedrite. By far the majority of veins are between H 25 W & I 50 I in strike and a great many of them follow the bidding. There are, however, some exceptions and strikes of U.S. & N.E. occur. Gunning classes these deposits with Lindgren's^ I T Lindpren, W.t Mineral Deposits 1928 silver-lead veins of mesothermal origin. 5. A common form of deposit in the Laraeau area is that of galena-sphalerite replacement in limestone. Little work has been done on these and information is scarce. The limestone replaced is usually grey to white and crystalline. Gunning states that "Solutions ascended along fissures, bedd-ing plains, or at contacts, in limestones and white quartz,—-small amounts of ankerite and occasionally some siderite, replaced the limestone." The suphides occur in streaks along 135 the bedding and are commonly pyrite, sphalerite, galena, and minor amounts of chalcopyrite. The silver content is general-ly low. Gunning blames the simple nature of the structure for the lack of concentration of the ore, believing that the low, simple folds permitted the ore bearing solutions to es-cape • g This group Gunning classes with Lindgren's "Silver-FTliindgren W., "Mineral Deposits 1928w pp 657 and ¿77 lead replacement deposits in Limestone", also of Mesothermal origin. Lindgren points out the intimate connection between such replacement deposits and veins. 6. The Quartz-tetrahedrite veins are the so-called dry ores of the Slocan and are poorly represented in the area; a discussion of them will therefor be deferred until that area is treated. 7. Several silver-lead veins are found in limestone in the area which differ from any of the previously described forms. Little metallic mineralization is present except silver-bearing galena and freibergite in a gyngue of calcite or milky quartz. Replacement has taken a minor part and the veins are of the true fissure type. Good silver values have been obtain-ed even where no tetrahedrite was found showing that the sil-ver occured with the galena as a solid solution or else as a finely divided silver bearing mineral. 136 GENERAL CONSIDERATIONS The Distribution of the Ore Shoots Gunning} notes with interest that the ore deposits 1« Gunning, H.C., G.S.C., Mem 161 p 2~6 occur in distinct zones following the strike of the sediments which roughly parallel the euge of the batholith forming the western side of the area. These sediments have been tightly folded and dip steeply but have a very uniform strike. It is highly probable that the sediments lie in a trough of granite since granitic rocks occur on three sides. From these granitic rocks, or the magma which was their source, ascending eminations travelled along fissures and shear zones until they had de-posited their load of mineral. The parallelism is easily ex-plained on this ground since the prédominent fissuring and shearing is roughly paralleling the structure of the formations. The zone lying to the east of Trout lake is predom-inently valuable for its silver c ntent, while to the west of the Lardeau river gold is the commonest economic mineral. One of the most pronounced zones in the district occurs to the east of Trout lake. Here the deposits are all fissure veins carrying lead, zinc, and silver and usually some gold. Vary-ing amounts of argentiferous tetrahedrite is present. Relationship of the ore Deposits to the Country Rock The most favourable formation in the area appears to be the grey, carbonated rock ana the beds of limestone. Many fissure veins have developed in the slates, and carbonaceous 137 rT' or argillaceous schists. Few generalizations can he made. Little difference in the degree of mineralization can he observed except tnat the massive greenstones and quartzites and the chlorite schists seem to have heen relatively unfavourable and the limestone the most favourable for replacement. The Genesis of the Ore Deposits. There is little doubt that heated, ascending solut-ions have caused all the different types of ore deposits found >in the area. These solutions, Gunning believes, originated during the final stage of consolidation of the magmas forming the various batholithic masses that surround the district. The range in temperature in the deposits found in close juxta-position from those exhibiting all the phenomina of extre<§®ly high temperature to medium temperature deposits such as the replacement of limestone by galena, is of -nterest as indicating a wide variation of temperature during the period of mineral-isation and even the possibilities of a progressively falling temperature such as would obtain during the last stages of igneous activity. Some of the dykes closely related to the Kuskanax batholith have themselves been mineralized suggesting that the mineralization must have taken place at a very late stage in the igneous activity since Cairnes^has shown that the Kuskanax is the youngest granitic mass in the area. JJo younger igneous l. uairnes, (;.&..G.S.C., Summ flpt 1928 138 rooks are known that could have "been a source of the ore bearing solutions. Gunning could find no trace of more than one period of mineralization. From their association with the Kuskanax batholith as a late phase of its intrusion it seems clear that the mineralization can be considered to be late Miocene or early Tertiary in age. Paragenesis; Despite the widespread nature of the min-eralization there is a striking similarity in its occurence even in the deposits of wiuely differing temperature which points to a community of source for the solutions forming them and to a single period of mineralization. The constancy in the paragenesis bears this out; the order of crystallization being as follows. Pyrite, the earliest mineral, sphalerite, tetrahedrite, and ehalcopyrite, and galena. Pyrrhotite gener-ally succeeds pyrite and proceeds sphalerite. This is the same as that obtaining in the Windermere Map Area. THE SLOCAM AREA General Geology; This area will be taken to include the area lying along the Kaslo-Nakusp railway between those two towns. It is bounded on the south and west by phases of the Nelson batholith and on the north by the Kuskanax bathol-ith and thus represents a fragment of the old sediments surr-ounded on three sides and probably underlain by granite. The formations conprising this remnant range from Precambrian to Triassic, although a great gap exists between the top of the mi the Precambrian which is only developed in two or three f jmall patches, and the bottom of the Triassic Kaslo series. The two Triassic series, the Kaslo and the Slocan, make up practically the whole of the district. A large number of dykes cut both series and are genetically connected to the granite. Economic Geology; The ore deposits of the Slocan are usually classed as "wet" or "dry", the latter being those whose chief value is silver in a gangue which is predominently quartz. Cairnes^found that the dry veins were in or close to IT"Uairnes, C.E., G.S.C.,Summ Rpt 1928 granitic intrusives and generally higher temperature than the wet ones. The silver values in them are usually in association with galena and sphalerite which generally occur in subordinate amounts. The wet ores are composed essentially of galena associated with more or less sphalerite. Siderite is the most important gangue mineral although some quartz and calcite is often present. High grade silver minerals such as freiber-gite, native silver and argentite, & the ruby silvers are common with both types. Pyrite is always present increasing with depth and chalcopyrite and pyrrhotite also occur. Both chalcopyrite and gold have been known to occur in commercial quantities but are generally present in extre^ gifflly small quan-tities or entirely absent. Cairnes believes that two main processes are respon-sible for the occurence and extend of the veins; fissuring and 140 lacement; and of these two he regards the former as the f more important. The shearing and faulting along those fissures was repeated after the consolidation of the earlier stage of mineralization for it was brecciated and healed again at least once. He referrs the ultimate origin of the ore bearing eol-ations to the Nelson batholith, and particularly to the Nelson £ granite , which cuts the various formations with tongues, apo-ST"Calrnes. C.B., G.S.C.. Summ Rpt 1928 p kJBX fhyses and dykes, ^e was interested to note the occurence of mineral within the rocks of the batholith and that there was a decided zonal distribution of minerals with regard to the bath-olith. The ores nearer the main intrusive being predominently of the dry type and those farther away of the wet. This he believes is due to the decrease in temperature as the mineral-izing solutions travel away from their source. It is notice-able also in the vertical zoning of individual ore shoots. There is a predominence Northeast-southwest strike with a south east dip while the prédominent strike of the coun-try rock is northwest-southeast. Cairnes believes that the direction has been controlled by a system of master joints. 1 Replacement has played a very important roll and con-1. Bateman. A.M.. Econ. Geol. Vol XX Ho 6 g 571 sequently the composition of the country rock is of great im-portance. The two factors that control^ the degree of replace-ment are the lime content of the rock and the extent of the ire-mineral brecciation» The former of the two factors is commonly found in the Slocan series where limestones and calcareous argillites are common rocks* © Lindgren classes the Slocan ore deposits as being of mesothermal origin and of the tetrahedrite-galena-siderite ST Lindgren. W.. "Mineral Deposits. 1928" p 645 type. 3 Cairnes points oat an interesting fact that the 3. Cairnes. C.E..G.S.C.. Summ Rpt 1928 p 1Q5A Kuskanax batholith exhibits a remarkable paucity of mineral-ization related to it which is peculiar considering the fact that Gonning^found ores of a similar nature to the Slocan type 4. Gunning. H.C., G.S.C.. Mem 161 to be intemately related to it. THE KOOTEHAY LAKE AREA General Geology; The stratified rocks of this area lie on each side of Kootenay lake which occupies the Purcell trench between the Selkirk range and the Purcell range, the most easterly and the moat westerly representatives of the Columbia and Rocky Mountain Systems respectively. By far the greater part of the area is underlain by Precambrian sediments com-prising members of the Upper Purcell series and the Windermere series (Ainsworth series), the former occupying the northeast-ern and southeastern comers of the area, and the latter both sides of the lake and, in fact, all the rest of the area ex-cept for a small strip of Triassic sediments lying to the west 142 of the lake and paralleling it. The lower half of the area is bounded on the west by the northeastern corner of the Kelson batholith. Two stocks, one of considerable dimension, occupy positions to the east of the lake. A late stage of the bath-olithic intrusion is manifest in a number of lamprophyre dykes. Economic Geology; Apart from the Blue Bell^mine, all the 1. Walker. J.F.. G.S.C., Summ Rpt 1928 p 129A mineral deposits of economic significance occur on the west side of Kootenay lake close to the town of Ainsworth. These are mostly associated with limestone bands in the Ainsworth and Slocan series. The ores consist of pyrite, galena and sphalerite in a gangue of calcite, siderlte, quartz, and fluorite. Native silver occurs as a secondary mineral in a few places. Pyrr-hotite and chalcopyrite are occasionally present. Two types of deposits have been recognized. Fissure g veins and replacement deposits. Schofi^d believes these two HTschofield, S.«T., G.S.C., Mem 117 p 23 et seq. to be entirely contemporaneous in their formation. The fissure veins usually have a strike of KW or HE but both NS & EW strikes occur. Genesis; Schofield concluded that the ore-bearing sol-utions eminated from the granite in the pneumatolitic stage of oooling and ascended the fissures leading from their source until favourable conditions obtained for them to deposit their 143 fcorden of mineral either in the fissure or by replacing the wall rock. This leads to the conclusion that the ore deposits were formed during the last stages of the cooling of the granite masses and were therefore probably late jurassic in age. The similarity between the mineralization of the for-going areas is quite striking. Both types of deposits and the minerals developed are the same and there is little doubt that the solutions that formed them came from the same deep source. The similarity over so wide spread an area suggests to the writer that the source of the mineralizing solutions must be deeper and more universal than the immediate granite mass in the particular section. The fact that Gunning found mineral-ization which appears to be connected with the Kuskanax bath-olith that was essentially similar to that found in the Slocan which was related to the Kelson batholith and not to the Kusk-anax suggests a common source that was deeper than either of these two bodies and may even have been the parent magma from which each was in turn derived. THE CRANBROOK AREA General Geology; The area is underlain almost entirely by rocks of Precambrian age belonging to the lower Purcell series and contains the oldest Precambrian rocks known in British Columbia. In the southeast corner of the Map Area few small patches of rocks of Upper Paleozoic age (Devonian and Mississippian) are found separated from the precambrian rocks 144 a vast unconformity. Igneous activity resulted in the ex-trusion of lava daring the Prec&mbrian times and the intrusion of associated sills over a wide area, but apart from that, iso-lated stocks and dykes of Jurassic, granite form practically the only igneous rocks in the area. Economic Geology; Schofield^has divided the metallic 1. Schofield, a.j., G.S.U.. Mem 76 p 153" mineralization of the district into three main classes:-1. Silver lead deposits 2. Gold quartz deposits 3. Gold copper deposits 1. The silver lead deposits are, at present, by far the most important. They occur in the oldest of the precam-brian rocks (Aldridge) in its quartzitic phases. The mineral-ization consists of pyrite, pyrrhotite and galena either as fissure veins or replacement deposits in argillaceous quart-zltes. The gangue includes garnet, diopside, caicite, and quartz. Arsenopyrite and chalcopyrite rarely occur. Native silver is found occasionally in the oxidized zones. Schofield gives the following as the paragenesis of the ores starting with the oldest mineral to crystallize out. 1. Magnetite, 2. Actinolite, 3. Garnet, diopside, some pyrite and arsenopyrite, 4. Pyrite, pyrrhotite, sphalerite, and galena, 145 5. Calcite, 6. Cerussite, pyromorphite, native silver and limonite 7. Jamestonite. 2 Genesis; Lindgren classes these as hypothermal deposits 2. Lindgren, w., "Mineral Deposits7"l9^b" p 779 g of the lead-silver-zinc type. Schofield considers the presence 3T"5ehofield, S.J.. G.S.C., Mem 76 p llf of the minerals garnet, diopside, actinolite and muscovite which are entirely restricted to the ore deposit, as diagnostic of -fairly deep seated mineralization. Schofield believes, from this and other evidence, that a granite mass, probably related to the Nelson batholith, underlies the district at no very great depth, and from this mass eminated the solutions that were responsible for the extensive mineralization. Schofield and Lindgren consider the silver lead de-posits of the area to be related to the deposits of the Coeur d'Alenes but that the former were formed under less extreme conditions of temperature and pressure. The inferred connection with the Jurassic Nelson batholith suggests the probability that the ores were deposited during late Jurassic times. Two main districts are recoagnized with the following important properties. 1. The Moyie district; with the StEugene, Society Girl and Aurora Mines. 146 2. The Klmberly district; with the Sullivan, North Star and the Stemwinder Mines. The ore deposits of the Moyie district are connected with two main parallel fissures striking a little north of west and dipping about 70° south. They cross the axis of an anti-cline composed of argillaceous quartzites of the Aldridge form-ation. The Kimberly is also underlain by argillaceous quart-sites of the Aldridge formation which from the eastern limb of a large anticline. They strike north south and dip to the east. The ore-bodies eonform to the dip and strike of the quartzites with a commercial foot and hangingwall. A decided zonking appears in the ore bodies which grade from a fine mix-ture of galena and sphalerite in the center to a mixture of pyrite, pyrrhotite, and sphalerite near the margins. The whole ®re body is surrounded by a layer of chert which gradually phases into the unaltered argillaceous quartzite. 2. 'l'he gold quartz veins have a comparatively limited distribution. They occur as true fissure veins of considerable width and persistance cutting the argillaceous quartzites of the Creston formation. They contain free gold and pyrite in a gangue of quartz. 3. The copper-gold veins have a wide distribution throughout the district, although no bodies of great economic importance have been developed in them as yet. They are always 147 ífound associated with the Purcell sills which are almost ex-elusively intruded into the Aldridge formation. The Purcell sills vary in thickness from 2 feet to 2,000 feet and consist mainly of hornblende gabbro with large, irregular differenti-ations of hornblende granite with which the copper deposits are associated. These deposits occur in two forms; a. Large irregular masses or differentiations. b. Veins. a. The differentiations usually occur in the interior of the sills and are as large as 200 or 300 feet in diameter with gradational boundaries. Through these masses chalcopyrite, pyrite and pyrrhotite occur sporadically. b. The veins occur as shear zones cutting the sills and are filled with quartz carrying chalcopyrite, pyrite and pyrr-hotite. Native copper and galena occasionally occur. Schofield^finds clear evidence for associating the mschofield, S.J.. G.S.C., Mem 76 p 14T copper-gold deposits genetically with the Purcell sills. He found all gradations ^ rom differentiates to true veins and that the veins always pinched outjin passing from the sills to the quartzite. The conclusion is therefor unavoidable that these deposits are of Precambrian age. THE YMIR AREA General Geology; This area lies to the north of the town of Nelson and close to the south east corner of the Nelson 148 batholith and there seems little doubt, from the number of intrusives related to that body ooeuring as stocks, basses and dyke-like intrusives, that the whole area is underlain by granites at no great depth. Overlying the granite basement are a succession of the Summit (Windermere) series and the Triassic Pend D^reille and Rossland series. These formations strike roughly North-south and dip, as a whole, to the west. A great number of intrusives have cut these rocks ranging in time from the Augitej^orphyrite of the Rossland group of Trias-sic age to the Salmon River monzonites that have been tentat-ively considered to be Oligocene. The most expensively devel-oped are the granitic stocks and bosses related to the Nelson batholith. Economic Geology; The ore occurences of the Ymir area occur chiefly in quartz veins their economic values being main-ly gold, silver, and lead. They occur both in the granitic rocks of the Nelson batholith and in the metamorphosed rocks of both the Pend D^reille and Rossland groups. No ueposits were found in the Precambrian rocks in the area although in the Sheep Creek^area to the south quartz veins carrying gold values 1. G.S.C., Map 1068, 1909 Explanatory notes in free gold occur in rocks of that age. 1 Dysdale has classified the ore deposits of the Ymir TTPrysdale, C.W., G.S.C., Mem 94 p 41 et seqT area in two ways; as regards form, and mineral association. Form 1. Fissure veins cutting the formations, 149 2. Fissure veins or shear-zones striking with the formation. 3* Replacement in limestone. Mineral Association 1. Auriferous galena, pyrite, and sphalerite. They form the most important ores in the area. 2. Quartz with free gold, and pyrrhotite, chalcopy-rite and pyrite in small amounts. Commonly found associated with the dykes of the Rossland group. 3. Argentiferous galena, with small amounts of pyrite and sphalerite. Mainly in the monzonite. 4. Auriferous pyrite in a quartz gangue. 5. Low grade galena, sphalerite, and pyrite; chief values are in silver. Occurs in limestone. 1. The fissure veins cutting the formations are the most productive in the area. The gangue and the nature of the wall rock has controlled the degree of brecciation and so lo-cated the ore shoots. The mineral association of the types 1«, 2., and 3 are commonly found in these veins. 2. The veins striking with the formation are less important than the first group since the ore shoots are apt to he smaller and more irregular. There seems to be a close connection between these veins and the minor granitic intrus-ives. The typical mineral association from these deposites is 150 type 4. The strike of the veins of hoth the above types vary from N S'E to H 90* E hat few veins lie oat of this quadrant. 3. Replacement deposits are very scarce in this area. The ores are low grade galena, sphalerite, and pyrite with, silver and lead as the economic minerals. The wall rock is the crystalline limestones of the Pend D'Oreille series. Genesis; Drysdale concludes that the deposits owe their origin to ascending thermal solutions and places them in the class described by Lindgren^as Mesothermal Deposits, and further IT Llndgren, W.. "Mineral Deposits. 1928" p as formed at intermediate temperatures by ascending thermal waters and in genetic connection with intrusive rocks. He points out the absence of high temperature minerals and notes banding, comb and druse structures. He relates the formation of the fissures to the Jurasside revolution. The actual min-eralization would be an after effect of the intrusions and therefor late Jurassic. THE ROSSLAND AREA This area lies to the west of the Columbia river as it flows south and is close to the International Boundary and has proved to be one of the great mineral producing areas of British Columbia. General Geology; The oldest rocks in the area are of Triassic age and are cut by a great number of dykes of widely 151 varying composition, from the Triassic augite porphyrites of the Rossland group to the lamprophyres dykes of the late Mioc-ene. The principle intrusive is the Rossland Monzonite stock which was intruded during late Jurassic time, The whole area, is, however, characterized as being one of unusual igneous activity over a widespread period of time. Economic Geology; The Rossland ores are characterist-ically massive pyrrhotite and chalcopyrite with the main values in gold although some copper and silver is also present. Drysdale^describes the deposits as being formed by replacement IT~Drysdalet U.W.. G.S.C., Mem 77 p 44 along fissures and sheeted zones so forming veins. The origin-al fracturing has been localized oy structural features which have, consequently, influenced the position of the ore-bodies. He recognized five main types of deposits. 1. True replacement vein fissures. These show a uniform-ity in width and nature of ore minerals. These are best deve-loped in those veins traversing the augite porphyrite. E. Ore deposits occuring along sheeted or shear zones. These are generally in lenses and separated by barren sections of the zone. One or both walls are usually commercial. To this type belong the great majority of commercial ore deposits, 2. Cross fractures or fault fissures. These are of relatively little importance, but their intersection with main fractures may, sometimes, show enrichment. A'hey occur most 158 i'V gommonly in the upper portions of the mines. 4. Irregular impregnations, occur in very erratic form generally in members of the Mount Roberts formation. They are also found, however, in and around small pegmatite and aplitic syenite dykes. A considerable amount of gold has been mined from such deposits on occasions. 5. Gold bearing quartz fissure veins carrying pyrite, ohalcopyrite and galena. These are relatively unimportant and are more cavety fillings than replacement deposits. Over 90$ of the ore mined in the Rossland area eomes from the first three types. The Fissure Veins. From the foregoing the importance of the fissure veins can easily be seen. They stride roughly east-west and dip steeply to the north. They show a striking ten-dency to correspond to the strike and dip of the diorite por-phyrite tongues and often follow their contacts with the older formations for long distances. They are clearly younger, how-ever, since they can be seen cutting them. The veins can also be shown zo be younger than the monzonite in which they occas-ionally occur. The coincidence of the fissures with the dykes suggests a common cause which Drysdale believes is compress-ional stresses set up during the mountain building period of the late Jurassic. Through these fissures solutions, differ-entiation from a deep seated magma that had already produced a number of intrusives, seeped, replacing the walls and frag-mental material of the fissures by vein minerals. 153 ve r The rocks traversed by the fissures appears to play an important part in the formation of ore shoots and also on the distribution of values. The ore shoots on the contacts of the diorite porphyrite and augite porphyrite are usually high-er grade than those with a monzonite footwall or entirely in the monzonite. Drysdale suggests five factors in the localiz-ation of the ore shoots. 1« The physical character of the rock traversed has had a profound effect on the degree of fracturing and consequently on the ease of permiabilit.> to the invading solutions. In this connection it is well to bear in mind th«t it is not so much the absolute hardness of the rock as its hardness rela-tive to adjoining beds that is the controlling factor. 2. The contact of veins with faults having impervious walls or dykes have proved fevourable places for the formation of ore shoots. It is clear that in these cases the ascending solutions have been dammed back by the impervious barrier and so given a better opportunity to replace and mineralize the rock in that vicinity. 3. The intersection of mineralized cross-fractures with veins has been responsible for the location of certain ore-shoots. On other occasions impoverishment has oeen the^besult. Drysdale suggests that the mingling of the solutions from two sources may have been responsible for these phenomina. 4. The decrease in temperature and pressure as the sol-154 ations ascended must have produced a zone in which conditions for precipitation and other phenomina producing mineralization were most favourable. This is suggested by the occurence of high temperature minerals in the deeper parts of the veins. 5. The effect of the wall rock on the location of ore shoots suggest that its chemical character may have had a direct influence. The more siliceous diorite porphyrites seem to have been more easily replaced than the basic augite porphyr ite. The widespread metamorphism of the country rock with its resulting silicification suggests the ubiquity of the mineralizers. The Classification of the ores:- Brock^has made the 1. Brook, R.W., S.S.C.,Summ Rpt 1906" following classification of the ores:-1. Massive pyrrhotite anu chalcopyrite ores. Minor am-ounts of arsenopyrite, molybdonite and magnetite are found and traces of galena and sphalerite occur at one or two points. The gold is both free and in association with the sulphides. This is the typical ore of the camp. E. Massive coarse-grained oyrrhotite carrying only small quantities of copper and gold. 2. Veins of pyrite and marcasite with arsenopyrite and occasionally galena and sphalerite. Silver is sometimes quite important. 155 4, Impregnations of arsenopyrite, pyrrhotite, pyrite, molybdonite, a little chalcopyrite, bismuthite and native gold. This type occurs mainly in and around small pegmatite or aplitic alkaline syenite dykes. 5. Gold-bearing quartz veins carrying pyrite, chalcopy-rite, and galena in small quantities. The gangue is mainly the altered intruded rock with, in places, quartz and calcite. The following- minerals are the products of metamorphie changes. Biotite, silica, chlorite and hornblende are the most common but muscovite, tourmaline, garnet, and wollastonite alsa occur. Zeolites are not uncom-mon. The main value is in gold but copper and sometimes sil-ver are of economic importance in places. No relationship between the sulphide mineralization and the gold has been worked out save that the coarse pyrrhotite is invariable poor in gold. Genesis. Linagren^classes these deposits as gold-copper 1. Lindgren, W., "Mineral Deposits, 1928" p 7 73 2 deposits of hypothermal origin. Drysdale calls them "epigen-S7~Prysdale, U.W., G.S.C.,Mem 77 p 85-93" itic replacement deposits along shear or sheeted fissure zones" He believes that the action of hot, alkaline, aqaeous solutions o{ and gasses ascending from below under conditions M x high tem-perature and pressure has slowly transformed the brecciated 156 country rock of the fissure zones into ore. He considers that the coarse eutectic texture and mineral assemblage to indicate deep zones deposition, approaching that of contact metamorphism. Drysdale considers the ores to be derived from Ma deep-lying molten portion of a magma reservoir as 'after effects' of the intrusion of the Trail batholith." This same reservoir was probably responsible for the intrusion of many of the other intrusives as differentiates at different periods. Drysdale observed data that lead him to conclude that there had been more than one period of mineralization. He considered that the earliest eminations from the magma resulted in the depos-ition of eopper, sulphur, nickle, iron, lead, silver, cooalt, antimony, and molybdenum, and that it followed the intrusion of the Trail batholith. The second period consisted of alkali solutions carrying gold and that it followed the intrusion of the Coryell batholith. Age. Drysdale places the first period of mineralization at the close of the Jurasside revolution and the second at the close of the Miocene. THE BOUNDARY DISTRICT This area includes the important centers of Phoenix and Deadwood. It lies in the Midway mountains which are a subordinate group of the Columbia System and is a few miles from the International Boundary. 157 General Geology; The whole area lies close to the south contact of the Nelson batholith and minor related intrasives are common. The oldest rocks observed are of Triassie age and comprise the Knob Hill, Brooklyn, and Rawhide series of the Rossland Volcanic group. The only other sedimentary rocks known are the Kettle river formation which is of Oligocene age The igneous history of the district is a long and complex one, starting with the Triassie, intrusives rflated to the Rossland volcanics, including the rocks of the ^elson batholith, and terminated in the Miocene time with the intru-sion of the pulaskite porphyry. Economic Geology. The mineral zone is included in the altered limestone of the knob Hill series. Erosion has re-moved a great part of this series and, with it, doubtless, mineralized portions, leaving the ore-bodies in scattered frag ments of the once continuous formation. The two main sections the Phoenix Area and the Deadwood Area, will be treated se-parately. The Phoenix Area The ore occurs in troughs of jasperoid, in narrow troughs of limestone, along the contact oetween jasperoid and limestone, and between jasperoid and the quartzite rocks of the Knob Hill series. The following list of zones represent patches of the mineralized area isolated by erosion. 1. The flranby zone, 158 • r 2. The Brooklyn zone, 3. The Stemwinaer zone, 4. The Montezuma zone, 5. The Gilt Edge zone, 6. The Gold Drop zone. The ore-bodies are generally lenticular in form and vary from twenty to fifty feet in width with a length of 100 feet to a body up to half a mile long with a maximum width of 125 feet. The structural footwall is jasperoid and occasion-ally limestone. The hangingwall is usually a purely commercial one. Extensive fissuring has gone on over a wide period which LeRoyibelieves to be due to an after effect of the relief, by 1. LeRoy, O.E., G.S.C., Mem 21 p 53 et seq. failure, of the stresses causing the orogenic movements of the Jurasside revolution. These may have acted as channels carry-ing the ore-bearing solutions. Mineralization, The common metallic minerals are chal-copyrite pyrite, and specular he etite. Isolated bodies of magnetite are not uncommon. The gangue minerals are epidote, garnet, q.uartz, calcite, and chlorite; actinolite is also im-portant in places. Tremolite, serecite, zoissite, and apatite only appear in thin section. Ghalcopyrite is by far the most important economic mineral present; with it occurs the gold and silver. Genesis. Lindgren^has classed the ores of the Boundary 159 f . 17 Lindgren, W.. "Mineral deposits, 1928" p HHTo district as pyrometasomatic deposits not related to intrusive contacts. LeRoy points out that the mineral association in-dicates the contact metamorphic character of the zone of min-eralization, especially the extensive development of epidote and garnet. The widespread alteration of the limestone to these minerals indicates the introduction of foreign solutions. The silicification of the limestones to «jasperoid and chert took place at some period prior to the time of economic min-eralization. It has been supposed that an igneous mass, now possibly eroded away, was the source of the mineralizing sol-utions which worked along beds suitable either chemically or by reason of the degree of fracturing and so formed the de-2 posits. Brock noted that the granodiorite was, in one place, 2T"krock, ft.w., &.S.C..Summ Rpt 1902 p 109 altered to garnet, epidote, and actinolite suggesting that at least some of the Kelson batholith was intruded before the time of mineralization. The Deadwood Area The region is essentially no different from the Phoenix area, what has been said for the Phoenix being true for the Deadwood. Here, as before, erosion has separated the ore zones into a number of isolated areas. The two main ones are:-160 1. The Mother Lode 2. The Sunset, and some of the minor ones; 3. The St. Lawrence, 4. The Great Hope, and 5. The Marguerite. As at Phoenix the ore-bodies are flat-lying, tabular masses usually having a jasperoid or limestone footwall and a commercial hanging wall. The only difference in the mineral-ization is that, while at Phoenix actinolite is a relatively rare mineral, here it forms a great part of the gangue; and the place of the specular hemetite at Phoenix is filled oy magnetite at Deadwood. 1 Genesis. Here, also, LeRoy was able to see the evidence 1. LeRoyt O.E., G.S.C., Mem 19 p 40 of the contact metamorphic nature of the deposits. The source of the eminations he Delieves to be the Jurassic granodiorite intrusions. The evidence is nowhere very clear but no other hypothesis will serve. As in the Phoenix region the granod-iorite has been found to be mineralized in places suggesting, as before, that a considerable amount of granitic intrusion has proceeded before the period of mineralization. Age of the Boundary District. Accepting the hypothetical assumption for the origin of the ores their age would be re-lated to a late phase of the intrusion of the Nelson batholith 161 and therefor late Jurassic. Lacking furtner evidence this must be accepted. SUMMARY OF THE ECONOMIC GEOLOGY Some very interesting facts are apparent from the study of the various zones. First a remarkable sequence of mineralization can be observed from the north to the south along the contact of the West Kootenay batholith and westwardly along the south contact. Let us consider this for a few minut-es giving, in a brief summary^the salient points of each area. 1. The North-east Area. This may be taken to in-clude the Map areas of Windermere, Lardeau, Kootenay lake, Slocan, and Ainsworth. No essential difference is apparent between the mineralization of different parts of the area. The most important products are silver, lead and zinc. Some gold occurs but generally in minor quantities. The mineral assem-blage is generally characteristic of medium temperature de-posits formed in or associated with fissures by ascending ther-mal solutions. The area is of considerable extent and yet the minerals developed and their paragenesis is strikingly similar in every part of the area. Two main directions of fissuring are apparent, one N.25-75°W and the other, developed particularly in the Slocan, N 45-80°E. Other strxkes are present but rel-atively rare. 2. The Cranbrook Section. By far the most import-ant mineralization from the commercial standpoint are the lead silver occurences in the Kirnberly and Moyie districts. They 162 are developed as fissure veins and replacement deposits in the Precambrlan quartzites and are of fairly high temperature and probably associated with the Jurasside revolution. Two systems of fissures appear, one striking north and south and the other east and west; the former being in conformity with the bedding. On the whole these deposits seem to be rather similar, in some respects, to whose of the first section, but of considerably higher temperature. A very interesting ore occurence that has been given due prominence by Schofield is that of the copper-gold diff-erentiations and veins in the Purcell sills of the Moyie district. This mineralization is unquestionably of Precam-brian age and is the only known Precambrian mineralization in the area. It is not of any great economic importance at the present time but it is interesting to realize that an era that has produced such treasure houses stored in the early rocks of eastern Canada is not entirely without promise in British Columbia. 3. The Ymir Section. The southeast corner of the West Kootenay batholith has now been turned and this section is to the south of the main contact. A distinct change is at once apparent in the mineralization. While in the first two sections silver and lead were the economic minerals of prime importance gold and copper assuming a place of very secondary importance, gold now steps into prominence. Silver and lead still hold a position of considerable importance bat it is the increase in the gold content of the ores that is of in-terest. The ore deposits oecar almost exclusively in fissure veins having an average strike of from N8-90°E which have been produced by movements of the Jurasside revolution. They still belong to the same class, "Mesothermal Deposits" as the first two sections and have formed towards the close of the Jurasside revolution. 4. The Rossland Section. A still farther change is noticeable in the deposits of this region, gold having assumed the lead almost to the exclusion of all other minerals. Silver is still of some importance but lead is almost absent. Here, for the first time, copper assumes a roll of considerable economic importance and is, in fact, next to the gold, the most valuable metal present. The entire character of the mineral-ization has changed and the ore-bodies are classed as "Hypo-thermal Deposits". Chalcopyrite and pyrrhotite are the only sulphides present in any abundance. The ore-bodies occur as veins and replacement deposits in connection with an east-west fissure system which is believed to have been developed by tension after the relief of the pressure by the failure of the rocks during the Jurasside revolution. THere is every reason to believe that these ore de-posits were formed at far higher temperatures and deeper than those to the east and the original source was most probably closer to the point of deposition. Drysdale noticed an in-164 teresting phemoninon here; a second stage of deposition. He saw evidence that lead him to conclude that the earlier min-eralization, late Jurasside, was orecciated and healed by alkali solutions carrying gold during the Miocene. This is a very interesting fact and one that has not been brought out in any other part of the area. This would give the following two periods of miner-alization : 1. Late Jurassic, chalcooyrite, oyrrhotite, etc. 2. Miocene, gold. 5. The Boundary Section. This is the most westerly-section along the south edge of the batholith to be considered and seems to represent a step further in the direction of high temperature deposition than the Rossland mineralization. The economic mineral of paramount importance is now copper with gold and silver of secondary value. These are classed as "Pyrometasomatic Deposits'* and contact metamorphic minerals are present in considerable abundance. They are entirely replacement deposits in lime-stones and cherts of Triassic age. The age of the mineral-ization is given as late Jurassic. Generalizations From the foregoing it is clear that three periods of economic mineralization are known:-165 Age Related intrusive Mineralization 1. Precambrian, Purcell Sills, Copper, and gold. £. Late Jurassic, Helson batholith, silver, lead, zinc, copper and gold. 2. Miocene, Caryell batholith, Gold. Of these the first is of little importance and the third has only been observed in one district leaving the sec-ond to bear the main brunt of the responsibility for having produced one of the commercially important mineral regions of the world. The following tabulation may serve to bring out some facts more clearly. Jurasside mineralization Fissures Section 1. Silver-lead-zinc, IT £5-75 f Medium temperature (M5-80°E Slocan) Section 11. Silver-lead-zinc, H-S&E-W Medium temperature Section 111. Gold-silver-lead-zinc, H8-90°E Medium temperature Section IT. Gold-copper-silver, E W High temperature Section Y. Copper-gold. Replacement Contact metamorphie First the remarkable change in the mineralization going south and west along the contact of the batholith from medium temperature silver-lead-zinc deposits to high tempera-ture contact metamorphie deposits of copper and gold. The connection between the two types seems to be quite close since all types between the two appear. The implication is that they have a common source and that this source is deeper and more 166 universal than any igneous body in the immediate vicinity of the zone and is one that cannot he accepted without due con-sideration: a consideration that is out of thejscope of this paper. Further thought would suggest two alternatives to account for the phenominatt. 1, A deep seated, magmatic reservoir defferentiating gradually and ¿iving off the components of the West Kootenay batholith at various intervals. By this means mineralizers would he trapped in the secondary mass which would he given * off during the cooling producing ore-bodies close to the point of entry into the sediments. According to this;erosion may have cut down closer to the intruding body in the Boundary region than in the north exposing the higher temperature de-posits. 2. A deep seated magmatic reservoir might give all differentiates as batholithic invasions and at a later stage allow the excape of mineralizers which would ascend through the existing fissure system producing ore-deposits where con-ditions were favourable. Their connection with the earlier batholiths would therefor not be a direct one although in-directly, both by the development of fissure systems and by the heating of the surrounding sediments, they might have a profound influence on both the location of ore deposits and the nature of the mineralizati >n in them. 167 The following abservations may have a bearing on the discussion:-a. The mineralization all over the north-east from Upper Arrow Lake to Windermere lake and south as far as Ainsworth is almost identical in character. This suggests a common source which must, of necessity be a fairly deep seated one for eminations from it have covered so wide an area. b. That Gunning found mineralization identically similar in nature with that which Cairnes, in the Slocan, had associ-ated with the Kelson granite, apparently genetically connected with the Kuskanax batholith. The possibility at least is that neither granite is the source of the mineralization. c. The mineralization appears to have taken place at one period, the late Jurassic. This is rather indefinite for that in itself, may represent a long enough period of time for a number of periods of mineralization. d. A considerable amount of granitic rock of the area has been mineralized and is therefor pre-mineral, while none of the Jurassic plutonios have been observed cutting the ore. e. With the exception of the Slocan area, which is an isolated fragment caught in the mass of the granite, and one set of fissures in the Cranbrook area, by far the greater nu-mber of the vein systems appear to parallel the direction of the main contact of the West Kootenay batholith. This would 168 suggest that the main mass of the granite was in its present position before the formation of the fissure system that al-lowed the entry of the mineralizers. Whatever theory be accepted the ultimate community of origin seems fairly assured and also the fact that erosion has cut deeper into the zone of mineralization in the south. If the mineralization is independent of the immediate intru-sives it may be that the extensive igneous activity of the Boundary belt may have heated the intruded rocks so as to reproduce high temperature conditions even where the point of deposition is at some distance from the source of solution. 169 Chap VI GEOLOGICAL HISTORY The geological history is a varied and interesting one although rather fragmentary. The earliest known record is in the late PrecarVbrian and with many breaks, runs through to the present time. The history will first be taken xjp, much as the three previous chapters have been, with a deta.iled account of different sections and conclude with a summary piecing to-gether the fragments as well as possible. Events have been tabulated as well as pos&ible in Table 111 in the appendix. 170 r i HISTORY Off TBE NORTHEAST OF THE NELSON BATBOLITH. Precambrian The earliest known rocks in the area are the Purcell series and are probably Beltian in age. These were laid down in the Purcell continental basin. The Purcell 1 2 sea was certainly shallow and, according to Walcctt , not 1) Daly, H.A. G.SlC. Summ. Rpt. 1904 p 97A 3 connected with the ocean. Walker however, disagrees with 2) Walcott, Smith. Coll. Vol 57 1910 pi 3) Walker J.F. G.S .C., Mem 148 1926 p 12 this instancing the great thickness of the limestone beds and explaining the gap in the record of the fossils by the lapse of time between the Cambrian and the Precambrian. Rapid er-osion of a large land mass to the west poured sediments into this basin building up the Purcell series of the Kootenay Lake and Cranbrook Map Areas. The evidence for this continent and the proof that the sediments are derived from it has been 1 clearly observed and recorded by Daly who noticed the marked increase in the coarseness of the sediments in the Rocky Moun-tain geosyncline from east to west. After the deposition of the last of the Purcell formations there was a considerable uplift accompanied by some 4 5 folding and rnetamorphism . Walker also points out that the Windermere series is, in part at least derived from the older 171 •oldwr Purcells and laid down on their eroded and flooded sur-face. This series of formations was again uplifted at the close of the Windermere and the later Paleozoics formed, in part, from the products 4 Ibid P 13 5, Ibid P 15 of their erosion. The evidence of this land mass is adduced Toy Walker 13 Walker, J.F. Mem 148 G.S.C. 1926 p 15" 2 who does not agree with Schofield that they may have come 2) Sciofield, S.J. Trans Hoy Soc Can Vol Xvll p 95 1923 from the western land-mass Cascadis, The uplift at the clcse of the Windermere appears to have been accompanied by the in-3 trusion of dykes and sills of varying composition. This is TFWalker J.F. C.G.S. Mem 148 true for the Windermere map area at least. It is suggested that these may represent the final differention prodi cts of a deep seated magma whose larger intrusives have not been ex-posed by erosion but which may be genetically related to the later Kootenay batholithic intrusions in spite of the vast time gap between the periods of intrusions. 172 Paleogoic After the close of Windermere time the area was apparently uplifted and eroded, the products going to produce the later sediments. Walker adduces evidence for supposing the existence of a land mass in the region of the Purcell range and that, at least to the west, it was of considerable height. He again disagrees with Schofield that the material for the paleozoic sediments could have come from the Land Cascadis to the west of the present shore line, since he finds shore deposits in the area. The evidence for a vast lapse of the time between the elevation of the land at the close of the Windermere time and its re-submergance during the paleo-4 zoic is evident from the extensive unconformity that exists T T Schofield, S.J. G.S.C. Mus Bull. 55 p 1ST, between even the oldest Paleozoic rocks known in the area and the youngest of the Precambrian, and from the fact that gen-erally the youngest paleozoics are missing in some parts even the whole of the paleozoic is absent. The oldest paleozoic rocks known in the West Kootenay Area occur to the east of the Granbrook Map Area3" and Schofield brings out clear evidence 1) Schofield S.J. G.S.C, Mem, 76 p 43 for the extent of the unconformity there, Following this period of emergence and erosion the area to the east of Windermere Lake was flooded fairly deeply and into these quiet waters limestones were deposited. It would seem probable that the land was fairly low lying at 173 this time since the deposits in the seas of the time are relatively pure limestone with little evidence of erosive activity. The rather sudden change in the nature of the sed-imentation in the Ottertail seems to indicate a considerable elevation of the seaway. This elevation appears to have resulted in the draining of portions of the seaway as well as its general shallowing since both sun-cracking and erosion have gone on. This condition apparently existed until the close of the Glenogle when a further uplift took place resulting in a break in the sedimentation and a period of erosion. This break, while of considerable duration, was a relatively minor one and, on the submergance of the land again the members of the Wonah quartzite were laid down with little angular dis-cordance upon the eroded surface of the Glenogle and, in places, the Goodsir. The presence of the extensive limestones of the Beaverfoot-Brisco formation points to a deepening of the basin in whose quiet warm waters they are deposited. A further proof of the deepening and widening of the seas lies in the presence of these formations lying directly on the Ottertail and Goodsir formations in parts of the Area that were apparently land when the Wonah was being laid down. At the close of this time there came a period of cessation of sedimentation due to a shallowing of the seas, 174 followed by the deposition of the muds of the Mount Popster Shales in a sea that was still shallow. All through the sub-sequent Starbird period the sea was deepening as is evidenced by the increase in the quantity and purity of the limestones. Triassic Prom this time until about the Mississip-pian there is a break in the record of sedimentation and the next rocks appear to the west of Kootenay Lake. It would seeia probable that the movements leading up to the Permian revolution began to take effect at this time and that the elevated Windermere basin was never again submerged. Sub-mergance was effected in the west, however, and movements that were to produce the widespread flooding of the area be-tween the Arrow Lakes and Kootenay Lake began to take effect; producing the seawy in which the formations of the Milford group were laid down. In all probability the elevation of this time was not great since the basal conglomerate of the Milford shows little signs of transportation and the sediments of the group are all fine even though they were deposited close to the shore. After the depostition of the Milford group a re-elevation of the land took place accompanied by the widespread vulcanism so common to the Triassic of B.C.. During this time the pyroclastics of the Kaslo series were laid discon-formably on the Milford group and eroded members of the 175 Precambrian rocks and the accompanying dykes intruded. The Cessation of activity allowing for the disconformity at the top of the Kaslo series was only temporary and accompanied by wide spread submergance. Into the resulting shallow sea the muds and limestones of the Slocan series were deposited and the ashes and ejectmenta of renewed volcanic activity were dropped. Jurasside Revolution The crustal unrest of the period was evidenced by q. further elevation of the land which resulted in the final draining of the seas. The movement this time, however did not stop at a slight vertical uplift but continued to be effective until the broad, sweeping fold-ing resulted in the formation of the mountain ranges to which the present topograrhy is due. These orogenic movements continued throughout the Jurassic and were accompanied by the intrusion of the large bodies of granite known collectively as the Kelson batholith. While the intrusion of the granites are sufficiently abundant in the west Kootenay region to warrant the name of Batholith, ?ma.ller granite intrusions to the west seem to prove the genetic relationship between the Nelson batholith and the 1 tremendous intrusions of the Coast Range batholith as Bancroft T"Bancroft, M.ff. G.S.C. Suram Rpt 1917 p 29B HAS POINTED OUT. The genetic connection between the phases of the intrusives and the economic mineralization has been 176 established and has lead Bancroft to say that the period nis recognized as the most important ore forming period in the history of the Cordillera.* It is quite evident that the batholith or batholiths, are highly composite and comprise a number of periods of in-trusion. It is more than probable that each period of renewed crustal activity during the coarse of the revolution was accompanied by magmatic injection following the relief of pressure due to the upfolding. The relationship of the diff-erent phases to each other and to the economic geology of the area has not yet been worked out in a satisfactory manner and should prove a field for interesting and valuable research. Dawson^ has pointed out that the Triassic in Canada T~Dawson» G.M., Trans. Roy. Soc. Can., Vol 1 Sec 4 p 143 ¿«en hasAclosed by a period of revolution that resulted in a gen-eral elevation of the whole of British Columbia during the Jurassic period. This elevation was accompanied by crustal folding on a scale vast enough to produce the mountains ranges whose roots are still apparent in many parts of the province. There is no doubt that it was during this time that the in-jections of the batholithic rocks took place. This period of disturbance has been called the Jurasside revolution by Scho-field. 176 2 Cranbrook Section 2 Precambrian Schofield has inferred, from a study laid of the sediments, of the earliest Precambrian rocks^down in 2 Schofield, S.J., G.S.C., Mem 76 p 38 the Area, the Aldridge formation of the Purcell series, that an old landmass, possibly of Archeozoic age, was present be-fore the appearance of the Purcell sea. This landmass he further believes, was probably composed of acid gneisses and schists and that its topography was that characteristic of late maturity. This he infers from the nature of its erosion-al products. The Purcell Epoch; At this stage in the history of the area a portion of the crust was downwarped and the hollow so formed flooded to form the Purcell continental sea. While 3 7/alker believes this basin to be truly marine to the north, FWalker, J.F. , G.S.C., Mem 148 p 12 there seems little doubt that it was shallow throughout Pur-cell time in the Cranbrook area. Not only this but Scho-1 2 3 field, Daly Bauerman , and Walcott agree TTTaly, R.A., G.S.C.. Summ Rpt 1904 p 97 A 2 Bauerman, H., G.S.C., Rpt of Prog., 1882 p 25B 3~Walcott, Smith. Coll., Vol 57 1910 p T 177 in thinking that it is most probably, in part at least, a basin unconnected with the sea and the deposits in it, therefore, continental deposits. The occurence of repeated beds showing muck-cracks, ripple-marks and the casts of salt crystals seem to suggest that this is certainly true for parts of the Epoch at least. Schofield believes that the landmass that produced the sediments lay to the west of the sea and not further than the West Kootenays. The Aldridge Age; Schofield suspects the presence of some carbonaceous matter in these rocks and therefore deduces that the climate was humid. Prom the materials composing the sed-iments he further concludes that mechanical disintegration was in advance of decomposition. The evidence of the shallow water deposition throughout the Age suggests that depression and sedimentation were proceeding at approximately the same pace. The Creston Age; There seems little change in the condition of sedimentation to be read from a study of the formation. Ripple-marks are present throughout the entire formation. The Kitchener Age; There is evidence that the sea was deeper during this age thafc at any other time during the for-mation of the Purcell series by the presence of calcareous 178 ¥ members of considerable thickness. That no sweeping change took place is evidenced, however, by the ripple-marking that is quite abundant on many of the quartzitic phases. The Siyeh Age; At the close of the preceeding Age the seas evidently became shallower for the mud deposited in the Siyeh Age shows not only ripple-marks in great abundance but mud-cracks as xvell. Schofield suspects that the sea was shallower at this time than even during the Aldridge and Creston Ages. The presence of alternately green and purple beds suggests the alternations of climate from wet to dry. At the close of this age the Purcell lava,s were ex-truded a.nd, accompanying them, the intrusions of gabbro that have been related to them. The cause of this is obscure un-less it was caused by some crustal disturbance that was a a forrunner of the more important ones that were to close the Precambrian. It was this that caused Walker to make a break in the Purcell series and divide it at this point into the Upper and Lower Purcells. The Gateway Age. Schofield suggests that the climatic con-ditions during the Gateway were very arid producing the abun-dant salt crystals so common to the formation. Proofs of the shallow nature of the sea are abundant. 179 f Cambrian Period; The elevation at the end of the Precambrian caused the erosion of all sediments that may have been laid down upon the precambrian strata. It does not appear to have been very pro-found, however, nor does it appear to have been accompanied by much folding or other crustal distortion then or later for, on the resubmergence of the Roosville formation to the east during the Cambrian period, the Burton formation was laid down on it with little or no perceptable angular discordance. Paleozoic Devono-Carboniferous Period; It was not until the Devonian period, after some 3,000 feet of sediments had been eroded off the horizontal Pre-cambrian beds that a y( seaway again appears. This sea, while not spreading as far west as before was evidently deeper and clearly marine since the de-posits of the two periods were mainly limestones. After the end of the carboniferous no further record of sedimentation is left and the ne.jr<, event in the geological history is the folding and elevation of the Purcell Mountains. Jurasside Revolution Late Jurassic and early Tertiary. The immediate cause of the disturbances V7as an east-west compression that threw the sediments laid down in the Purcell sea into long north-south anticlinal and synclinal folds. Accompanying this folding was the intrusion of the 180 f granite stocks and bosses related to the intrusion of the major batholith to the west at the same time. The relief of stress by the failure of the sediments resulted in tensional forces which produced a certain amount of normal faulting. It is the erosional disection of this folded and elevated region through subsequent time that has produced the present Purcell range of mountains. 3 Ymir Section Precambrian The oldest rocks in the area are those of the Priest river Terrane and give a long record of marine sedimen-tation. Priest River Terrahre Epoch; The materials composing the rocks of the Priest River Terraom series lead to the conclusion that an extensive epi-continental sea covered the greater part of this area if not 1 the whole of it. Daly concludes that this was undoubtedly 1 Daly, R.A.> G.S.C., Mem 38 p 567 marine from the considerable thickness of dolomite that con-stantly appear. The direction of the parent landmass is not apparent from data found in the area but, .judging from evid-ence in adjoining sections, must have lain to the west, Daly believes that this land was generally composed of granites and gneisses and that it could not have been very close to the area. It is probable that its topography was relatively gentle. 181 The Summit Epoch, At the close of the Priest River Terrafre or at some period after a general elevation of the area took place, fol-lowed by extensive erosion. The extent of the interval can be estimated when it is realized that the upper part of the Lower Purcell series and the Dutch Creek and Mount Nelson series were laid down further to the east and north. Any granite intrusions that may have accompanied this elevation were not exposed by erosion at the time of the first resubmergance of the area since the rocks laid down on the weathered land surface show none of the products to be ex-pected from the weathering oi such rock. The Irene Age With the gradual sinking of the basin the beating of the waves on the ancient beaches as the sea crept over the old Precambrian land tore pieces off the exposed strata and ground them into the pebbles that form the Irene conglomerate. It was the spreading of the sea across the slowly sinking land that produced the widespread distribution of the gravels. Some effect of the crustal unrest that produced the depression of the area must have permitted the extrusion of thick lava flows that cover a great part of the conglomerate, and must have followed their deposition very closely, being, in fact, contemporaneous with the uppermost ones. Monk Age On the cessation of volcanic activity nor-mal sedimentation was resumed in the shallow sea with the de-182 position of the sands, muds and clays of this and the two succ-eeding Ages; the Wolf and the Dewdney. The coarser nature of the sediments during the Wolf suggests the possibility that 1 there was a minor elevation of the land at this time, Drysdale l~I)rysdale, C.W., G.S.C., Mem 94 p 42 suggests an arid climate with seasonal rainfall during all this time. Ripple Age Succeeding this was a period of relative quiet when the products of the erosion of the lowlying land were completely disintegrated and the residual quartz ground to a fine sand and deposited in shallow beaches where the detrital washed in by the tide covered the ripple-marks of the preceeding one. Beehive Age As weathering of the land proceeded muds were laid down in shallow deltas and lagoons upon the preceeding sands. These muds were exposed to the sun from time to time and show its effects in cracks. The first record of humble life is the. preserved in these muds is whenAworfes of the ancient beaches tunnelled through the plastic clays. The Lone Star Age The record of this age is nearly ille^ gible. It may be that for a time the waters were drained from the land to be later returned and in the new seas the limey sediments of the Lone Star formation laid down, or it may be that a slight deepening of the basin was all that occured. There is little probability that any drastic movement took place at this time. At the end of the Suminet Epoch there is a break in the 183 record for a long period of time. Some time after the formation of the Lone Star sediments the continental sea was drained and its hed raised well ahove sea level. Erosion must have been active at this time denuding the new formed land and pouring its products into the Rocky Mountain Geosyncline to the east. The extent of this erosion cannot be estimated since no data ha.s been secured to fix the time of the uplift but it must have been considerably since the gap in the stratigraphic record runs the gamut of the entire paleozoic a period that has produced many thousands of feet of sediments further to the north and east. During the greater part of this time there is little doubt that erosion had taken the place of sedimentation. Pfrgsazoic-Triasaic This long period of silence is at last broken at the beginning of the Triassic. The Pend DtOreille Epoch Once again we find a shallow sea flooding an area of low relief widely. Into this basin impure sands and muds were washed from the surrounding terrafoe and with them a shadow of coning events in the shape of some beds of tuff. The amazingly quiet nature of the previous up-lift is evidenced by the apparent conformity between the sed-iments produced and the sediments laid down so many ages ago. The inference is that the early elevation must have been a gradual, vertical adjustment of isostatic equlibrium very different from the adjustment to the horizontal compressional forces so soon to take place. The Rossland Volcanic Epoch; This quescent period was 184 brought to a close by a period of great disturbance and uplift-ing that resulted jn the profound deformation of the rocks con-verting them into all manner of schists. Accompanying these phenomona was the extrusion of the thick volcanic series known as the Rossland Volcanics that was a common event throughout the Triassic all over British Columbis. This activity was accompanied by the accumulation of thick beds of tuffs both as 1 continental deposits or water sorted. Rapid erosion was in T"Prysdale, G.W., G.S.C., Mem 94 p 42 progress throughout this time and interbedded with the tuff^ beds, occasional beds totalling several thousand feet in thick-ness, of reddish conglomerate» sandstones and some carbonaceous shale have accumulated. Jurasside revolution The movement initiated in the Triassic continued with increasing effect throughout the Jur-assic and were accompanied by the intrusion, at several stages, of granite cores in the hearts of the new oorn mountains. Con-tact aureols were formed adding to the complexiti^ of the strata already suffering from the effects of profound dynamic metam-orphism. Also related to the same period and possibly to the parent magma of the granite is the mineralization that took place and in parts of the district assumed economic proportions. By the opening of the Cretaceous period most of the stress had been relieved and the country settled down to a per-iod of quiet erosion which lasted until the close of the Mes-azoic when the stresses of the Laramide revolution, which 11 ne flung the sediments of the Rocky Mountain geosyncs^a into 185 fantastic folds was felt in this region also. The Tei^tiary Period Orogenic movement of a mild nat-ure is inferred from the presence of the Salmon River Monzon-ite of middle Tertiary age and was followed by a period of profound erosion to which, Drysdale believes, the present topography may be referred. At this time the topography was of a very gentile nature and it was not until a further uplift at the beginning of the Quaternary that erosion again became active. The entire region was ground down by the advances of the Cordillerian Ice Sheet whose retreat covered the area with drift. 4 Rossland Section The most noticeable thing about the geological history of this part of the country is the extent of the igneous ac-tivity to which must be attributed the mineralization that has made the area famous. Pend d Oreille Age ; Triassic The oldest record in the area is preserved in the rocks of* the Pend d'Oreille & Sutherland at Mount Rob-1 erts formations of Triassic age, Drysdale suggests that, TlTrysdale, C.W., G.S.C., Mem 77 p 244 prior to this time, the area may have been a part of the low-lying eastern shore of the old land Cascadia, dipping to the east into the shallow waters of the Paleozoic epi-continental 186 sea. This land surface was eroded to a state of peneplaination until a down^ wjifo submerged a great part of it to form what 1 Suchert calls the Vancouver sea which appears first in the T"~Su chert, C. Geological Soc of America Bull Vol XX "p~*463. Devono-carboniferous and persists through until the beginning of the Jurassic. It was into this sea. that the Triassic sands, muds and limestones of the Mount Roberts formation were laid down. At the close of the Paleozoic the effect of the grad-ually accumulating forces made itself felt in the area by a profound uplift which was naturally accompanied by vigorous erosion. The Rossland Volcanic Age. Sympathetic with this move-ment was the outburst of igneous activity that is so remark-able a feature of the Triassic all over 3ritish Columbia. Dar-ing this time the earlier formations were covered with a thick mantle of agglomerates, tuffs and lavas and at the 3ame time a number of augite porphyrite sills were intruded. Jurassic revolition Uplift and erosion continued car-ving out the physiographic features that were to become the Selkirk, Purcell and Columbia mountain ranges; the Rossland Mountain being a part o-f the latter, throughout the Jurassic, and culminated at the close of that period in tve sweeping folding of the Jurasside revolution. Into the hearts of these folds the large intrusive« related to the Felson Batholjth swelled and were accompanied by the intrusion of" a host of 187 apophyses, sills and similar "bodies. It is clear that the ear-liest" of these batholithic intrusives was at least partially cooled before the stresses were finally relieved since many of them show decided gneissic structure and the margins have been fractured and healed by the passage of mineralizing juices from within. An accompaniment of this was the production of econom-ic ore bodies iv the adjacent rocks. Drysdale suggests that the topography at this time was similar to that of the fiockies at the present time. During the Cretaceous this was worn down until, by the beginning of the Tertiary the granite hearts of the mountains were laid bare in many places and this land once more reduced to a state of peneplaination. The Laramide revolution It was by reason of this des-position of the tremendous quantity of the products of this erosion that stresses were set up in the Rocky Mountain geos-yncline the east which were relieved at the close of the Cret-aceous by the tremendous disturbances of the Laramide revolut-ion. The focus of the disturbance was, of course, the folding and overthrosting that produced the Rocky Mountains but in the Rossland area the effect was that of regional upwarping along the structure lines of the Jurassic revolution. Drysdale sug-gests the possibility of glaciation on the higher parts of the mountain ranges produced at this time from the presence of boulders in the early Tertiary conglomerates that are apparent-ly of glacial origin. 188 The Sophie Mountain Age, A new cycle of erosion was started by this uplift and the deposits of Sophie Mountain and Lake Mountain conglomerale were -orobably the products of rjvers run-1 ning over the Eocene land surface, Daly suggests, from a 1 Daly, R.A., G.S.C., Mem 38 p 352 study of the degree to which the pebbles forming these conglo-merates are worn, that the prevailing drainage was from east to we st. The Oligocene Epoch During the Epoch the intrusive of the Salmon River and porphyritic monzonite took place. Assum-ing that some of these represent the plugs of old volcanic necks the presence of rhyolitic lavas and tuffs can be inferred although, since erosion has removed all trace of them, this is highly hypothetical. The presence of the intrusives however, suggests a period of considerable crustal unrest with a con-sequent elevation and renewal of erosion. The Miocene Enoch. The last of the igneous activity took place at this time and assumed batholithic proportions. The characteristic of these intrusives is that they are marked-ly alkaline in composition. The main exposure is that of the Coryell batholith but belonging to the same general period is the Sheppard granite and the host of lamprophyre dykes that invaded the whole district. It is evident, from the coarsness of the Coryell Syenite that an immense amount of overburden has been eroded off to unroof it and the dissection that followed the uplift is 189 Miocene times formed the hasis of the present topography. Pleistocene Epoch. It is more than probable that the Pliocene uplift, so universal all over the continent, played a very important part in producing the conditions that led to the great Peistocene Ice Age. The district was swept during this time by the ice of the Cordilleran Sheet that advanced from the north and northwest and covered the whole, country. Drysdale suggests that some few peaks, over 6,400 feet above the sea level, stood above the general level of the ice aheet as nuna-taks. The effect of this sheet was to modify the existing top-ography profoundly but not to initiate any new features of im-portance. One effect, however, was to cover the country with a mantle of rrorainic. material. SUI3&IRY OF T50L0GI0AL IJSTORY Precambrian The earliest, record of events dates from the Precar-.brian (Beltian) time and tells of marine and fresh-water sedimentation in a shallow epi-continental sea. This sea flooded the whole Cranbrook section across what is now the Purcell trench, in which lies Kootenay lake, to just beyond its western slopes. To the north and sou th the old shore lir.e of this sea swept westward to the site of the present Columbia river as it leaves the Arrow lakes in the south and northward past the head of Upper Arrow lake until it passes out of the Map area. During parts of the Precairbrian there is little dou-bt that the greater -^rt of the area was flooded since remnants of sedimentation appears all over the area. The western part of this sea, the p^rts that covered the area, was shallow at 190 all times and extrer^Ly so throughout the Purcell epoch. Earth-movement is also indicated by the rising and falling of the crust and the consequent draining of the basin at least twice during the Precambrian. Before the close of the Purcell epoch the land emerged in both the Cranbrook and Ymir sections nor did the sea appear in the former area again until towards the close of the next period. Into this sea sediments were washed from the erosion of a land to the west. More than once was this ancient continent reduced to a state of peneplaination but each time re-elevation started active erosion again and a fresh cycle of sedimentation appear in the sea to the east. The climate was probably arid with seasonal changes throu-ghout this time and except for the total absence of life, not so remarkably unlike that of our own times. The winds blew and the rain fell. The sun shone even as now. Only the appearance of a land surface utterly destitute of vegetation must have been weird in the extreme. A short outburst of volcanic activity is apparent in the Ymir section early in Windermere time but is the only break in the record of normal sedimentation. Paleozoic At the close of the Precambrian a strong vertical uplift was felt all over the area and the seas gradually drain-ed away until no record is left of any. With the cessation of deposition erosion set in and started to cut into the sediments laid down during the previous period. The length of time that elapsed before a renewed crustal activity downwarped portions 191 of the area must have been very great for the earliest record of renewed sedirrentation is in the Upper Cambrian. Very different from the wide flooding of the Precambrian is the record of the Paleozoic. The seas now lapped the shores of the old Precambrian landmass along the ea.st side of what is now the Columbia river by Windermere lake, and it is only in this part of the area that any record of the greater part of the Pla-eozoic is preserved. The middle Cambrian strata give indication of a landmass that previous erosion had reduced to a state of maturity, whose rivers were no longer bringing down any quantity of sediment and in the quiet, warm waters along the shore, lime-stone could be laid down. Before the close of the Period, how-ever, an elevation of the land took place that renewed erosive activity and preceeded the further elevation that droned the sea itself. The same series of events characterized the Silurian and Devonian. The close of the Paleozoic Era was preceeded by a much more widespread crustal downwarp producing Devonian and Carboniferous limestones in the Cranbrook Area and Carboniferous sediments at other points. Triassic The disturbance of the Appalachian revolution pro-duced a further downwarp and a wide folding of the land at all parts of the area except the south east corner where no record of mesozoic sedimentation is preserved. The rest of the area was covered by a shallow sea into which active erosion poured a considerable flood of sediments. The most striking phenominon of the Triassic, however is 192 the tremendous outburst of volcanic activity that covered the country with thousands of feet of volcanic tuffs, brescias and lava flows completely masking the normal sedimentation in most places. Following this was a period of quiescent and active erosion that reduced the whole area to a state of peneplaination. A downwarping of the Slocan and Kootenay lake areas produced a local basin of considerable extent into which a large quantity of muds were poured from the partially peneplained lands and in which limestones were deposited. Jurassic The Triassic was closed by the orogenic movements produced by a steadily increasing thrust from the west that res-ulted in the series of effects that are known collectively as t the Jurasside revolution. From that time on no evidence has been found of any part of the area being submerged beneath the sea. The accumulation of pressure was relieved by the buckl-ing of the sediments to from the nucleus of the ranges of the Columbia mountain System in the area. Into the hearts of these folds the various granitic intrusives of the Nelson batholith, with all its related bodies, worked, which subsequent erosion has exposed. Towards the close of this time an escape, or rather escapes, of mineralizers occured which are responsible for the various ore-bodies that have made the district as a whole famous. With the cessation of active uplift erosion began once more to assume the predominence and the land was again reduced to penet)laination. 191 Tertiary The last great event that has distorted the earth* crust in the area is the Laramide revolution with which the Mes ozoic closed. While to the east the Rocky mountains were up-folded and overthrust the only result in the area was a very pronounced uplift, with a consequent renewal of active erosion the intrusion of further granitic, fcatholithic rocks, and the accompanying mineralization that took place in the middle of the Tertiary. Pleistocene The Tertiary was closed by a marked and univer-sal uplift, and the advance of the Cordilleran ice sheet in the Pleistocene completed the work of the Tertiary erosion to give us our present topography. With the final retreat of the ice sheet a mantle of glac-iation dit^ritus, till and stream sorted gravels was left cov-ering a large portion of the land, and, with the unloading of the ice off the land the continent rose several hundred feet higher than during the Pleistocene and at that level it stands today. CHAP ¥11 SUMMARY & CONCLUSIONS Stratigraphical geology It has been shown that a fairly continuous record is preserved in the area from the late Pre-cambrian (Beltian) to the close of the Triassic at which time the area emerged from the sea for the last time. The record, from the close of the Precambrian to the top of the Paleozoic, is found only in the area round Windermere lake any deposition that may have taken place elsewhere during this time having 194 "been eroded away. Table I shows the correlations that have been suggested more clearly than can be told in words. The attention of the reader is drawn to the following which are of considerable in-terest since the data on which they are based has been adduced fairly recently by Walker end Cairnes. These officers of the Geological Survey have been working in the area for the past f four or five years and data collected by them has been used to supplement the conclusions of the earlier geologists on whom the burden of the original work fell. In a region of the complexity of the area considered, no one man can be given the lions share of the credit. The imagin-ation is most readily fired by the work of the pioneers and the men who immediately follow them, to whom is due the credit of having established a solid foundation upon which the later work could be securely bmilt; such men as G.M.Dawson, Brock, McConnell, and Daly. The importance of the work of the men who follow, LeRoy, Schofield, Drysdale, Bancroft and others, must not be minimumized, however, for without them the foundat-ion, no matter how brilliantly conceived, would have remained a foundation. Finally we come to the man of today and tomor-row who have the opportunity of prying more clearly and, thanks to a better understanding of the problem as a whole engendered by the previous work, delving with a closer insight into the fundemental causes and the theoj?£tical considerations that are really the back-bone of the science. 1. The Priest River Terrain has been correlated with the 195 lower Purcell series. 2. The Windermere, Ainsworth, and Summit series have been correlated. 3. The Triassic age of the Slocan, Kaslo, Pend d'Oreille, and Rossland groups has been suggested. The fairly detailed description of the various formations is nothing more than a summary of the descriptions given by the workers in the areas in Tfhich they are found. Igneous geology The first fact that seems clear at present is that in the pre-Mesozoic period igneous activity is not of great importance With the advent of the Triassic, however, a record of wide spread vulcanism is immediately evident. There is little dou-bt that the whole of British Columbia west of the Rocky Mount-ain^ geosyncline and southeastern Alaska must have been the scene of vulcanism either on a scale undreamed of at the present time or, what is much more probable, continuing intermittently for a tremendously long time. The tremendous sections of pyroclastics and related flows at widely different points in British Columbia and Alaska is a source of never decreasing interest to the writer. Whether this was an independant or a related phenominon is in doubt, but the fact remains that the next event of geol-ogical importance, the Jurasside revolution, was accompanied by the intrusion, on a vast scale, of the West Kootenay batholith. The first fact of striking significance is the extremely complex nature of this batholith which has been shown to be composed of a number of related intrusives varying widely both in compositions; and in Athe time of their intrusion. The correlations of these bodies over any extent of the area is impossible with the present state of knowledge but is an interesting problem which when it is solved, will doubtless through light on the theory of batholi-thic intrusion, differentiation of deep seated magams, assimil-ation by intruding magmas, mineralization and other kindred subjects. There is little doubt that the painstaking care, patience, and skill required to solve such a problem will be amply repayed by the results obtained. This period of plutonic igneous activity is the most ex-tensive known and also is associated with the most important ore bodies in the area. Igneous intrusives of a very similar type are known in both the Oligocene and Miocene and with the latter a second stage of economic mineralization is known. The only feature of special note is the alkali nature of the majority of the rocks of the Miocene group. Both the Jur-assic and Tertiary periods of activity seem to have been closed by the widespread intrusion of lamprophyre dykes. The Economic Geology Several facts of considerable interest have been brought out by a consideration of the economic geol-ogy of the area. 1. There are three main periods of mineralization;-a. The Precambrian; not of great economic importance. b. The Jurassic; the main period of economic mineralization. c. The miocene; the deposition of gold in economic quan-tity but of no great areal extent. Considering only the Jurassic mineralization, the following facts are worth remark. 196 2» The ore-deposits range from medium temperature fissure veins of silver; lead and zince to high temperature replacement with copper and gold of contact metamorphic origin. It is most interesting to note that almost all grades between these two are present. 3. Still more remarkable is the fact that there is a geo-graphical sequence in these types with the medium temperature deposits in the north east and the high temperature deposits in the southwest and a zone OJ£ mineralization in a rough semi-cir-cle between the two, along which progressively intermediate types may be found. 4. The direction of the mineralized fissures have a tend-ency to parallel the main area of batholithic intrusion sugg-esting that the batholith controlled the direction of fissuring and was most probably in place at the time of fissuring and therefore during the time of mineralization. In addition to these observations the following conclusions have been tentatively drawn. 1. A magmatic source, common for the different intrusives forming the batholith and the mineralizing solutions. The com-munity of the mineralizers as regards ultimate origin seems re-asonably assured. 2. The possibility of the mineralizers have been transported in the body of the intrusives drawn from the parent magmatice reservoir and given off during the cooling stage, 3. The possibility that the mineralizers may have come direct from the magmatic source independently of the subsiduary 197 intrusives, and after they had cooled. This theory is rather favored by the writer. Indirectly the batholiths, both by their determination of the location of the fissures and by the heating of the surround-ing rocks, would have a profound influence on the location of the ore-deposits and the nature of the minerals developed in them. There is little doubt that the erosion has cut deeper into the zone of mineralization in the south of the area than in the north thus exposing the higher temperature minerals. Geological History An effort has been made to trace the history of the area from the Precambrian to the present giving a brief account of the various seas and the revolutions that produced the mountain ranges and finally the more recent agents of erosion that have combined to produce our modern topography. It is unlikely that anything at all new has been brought out except the fact that the Purcell sea, during Windermere time (Late Precambrian) and may have been a good deal deeper to the north than was believed by the earlier geologists In the body of this paper an effort has been made f\gjPm time to time to indicate certain lines of study that appear to give promise of rich reward. In an area the size of British Columbia and one that is as little known geologically the danger of thinking that an area once mapped is finished with and the pos-sibility of profitable geological research over, is always pre-sent. It should be remembered that the thorough working out of one critical area may give a key to the geology of half a prov-ince and have a marked influence on the geology of the rest of the world, TQQ BIBLIOGRAPHY Allan, J.A. "Geology of Field Map Area, B.C. & Alberta Can Geol Sug., Mem 55 1914 Bancroft, "The Lardeau Map Area, B.C." Can. Geol. Sur Mem 161 1929 Bancroft, M.F. "The Lardeau Map Area, B.C." Can. Geol. Sur.. Summ Rpt p 107A 1921 Bancroft, M.F. "Slocan Map Area, B.C.* Can Geol Sur. Summ Rpt p 39B 1919 Bancroft, M.F. "Investigations in the Slocan District, 1917 B.C." Can Geol Sur. Summ Rpt p 28B Bancroft, M.F. •lardeau Map Area, B.C." 1920 Can Geol Sur. Summ Rpt. p 94 pt A Barreil, J. •Relations between Climate & Terristrial Deposits" Jour, of Geol Vol 16 pp 159 - 255. 1908 Bateman, A.M. "Silver Lead Deposits of Slocan District Econ Geol.. Vol XX No 6 p 554 "1925 Bauerman, H. "Geology of the Country near the 49th Parallel west of the Rocky Mountains" Can Geol Sur., Rpt of Prog., pt B 1882 Brock, R.W., "Preliminary Report on the Boundary Creek District, B.C." Can Geol Suf. Ann Rpt pt A p 92 1902 Brock, R.W., "The Lardeau District, B.C." Can Geol Sur.. Ann Rpt. Pt A p 42 1903 Brock, B.W., " The Lardeau District, B.C." Can Geol Sur., Ann Rpt pt A p 80 1904 Brock, R.W., "The Lardeau District, B.C Can Geol Sur., Summ Rpt. pt A p 84 1906 Buddington, A.F. "Geology and Mineral Deposits of South 1929 eastern Alaska» U.S. Geol Sur. Bull 800 Burling, L.D., cu cxu x oa u w ^ — « — — -WA Cambro-Ordovician Section in the Beaverfoot Range, near Golden, B.C. 1922 Geol Mag., Vol 59 p 452 Cairnes, C.E. "A geological Reconnaissance in the 1928 Slocan and Upper Arrow lakes areas, Kootenay District, B.C.* Can Geol Sur. Summ Rpt. Pt A p 94 C&apin, T. "Geology and Mineral Deposits of South 1929 eastern Alaska." U.S. Geol Sur.. Bull 800 Daly» R . A . » »North American Cordillera, ^o'rty-ninth 1912 Parallel." Can Geol Sur., Mem 38. Daly, R.A., "Geology of the Selkirk & Burcell Moun- 1913 tains at the C.P.R. main line." Can Geol Sur.F Summ Rpt p 156A. Daly, R.A., "A geological, Reconnaissance between 1915 Golden and Hope along the C.P.R»* Can Geol Sur., Mem 68. Daly, R.A., "Pestschrift zum siebzigsten Geburtstage 1906 von Rosenbusch* Daly, B.A. "The Secondary Origin of Certain Granites." Am Jour of Sc Series 4 Vol 20 p 185 1905 Daly R . A . , " Proc Am Acad Arts & Sc., Vol 45 p 219 1910 Daly, R.A. "The Mechanism of Igneous Intrusion" 1903 Am Jour, of Sc Series 4 Vol XV.XVl & 1908 Daly R.A. "Geology of the Western Part of the Inter-national Boundary," 1904 Can Geol Sur., Summ Rpt Pt A p 91 Dawson, G.M. "Report on the Area of the Kamioops 1894 Map Sheet, B.C.* Can Geol Sur., Ann Rpt pt B Dawson, G.M. "Notes on the Triassic of the Rocky 1883 Mountains, B.C. Trans Roy Soc of Can., Sec 17 p 143 Dawson, G.M. "On a Portion of the West Kootenay Dist.1889 B.C. Can Geol Sur., Ann Rpt., Pt B Drysdale, C.W. "Ymir Mining Camp, West Kootenay, B.C. 1914 Can Geol Sur., Summ Rpt. p 33A Drysdale, C.W. "Slocan Area, Ainsworth and Slocan Mining Divisions, B.C." 1916 Can Geol Sur. Summ Rpt p 56A 200 Brysdale, C.W. "Ymir Mining Camp, B.C.* Can Geol Sur, Mem 94 1917 Brysdale, C.W, "Geology & Ore Deposits of Rossland B.C." 1915 Can Geol Sur Mem 77 Brysdale, C.W. •Geology of the North Thompson Valley below Kamloops B.C." Can Geol Sur. Pt A p 115 1912 Gunning, H.C. "Geology & Mineral Deposits of the Big Bend Map Area, B.C.* Can Geol Sur, Summ Rpt. p 123 1928 Gunning, H.C, •Lardeau Map Area, B.C.* Can Geol Sur. Mem 161 1929 Gwillim, J.C, Can Ree Soc. Vol Vll 1897 LeRoy, O.E. "The Geology between Proctor & Midway, 1913 B.C.* Can Geol Sur. Guide Book No 9 p 61 LeRoy, O.E, •Mother Lode & Summet Mines, Boundary District, B.C.* Can Geol Sur. Mem 19 1913 LeRoy, O.E. "Geology & Ore deposits of Phoenix, Bound ary District, B.C," Can Geol Sur. Mem 21. 1912 LeRoy, O.E, •Slocan District, B.C. Can Geol Sur. Summ Rpt p 123 1910 Lindgren, W, "Mineral Deposits." McConnell, R.G, "On the Geological Structure of a Portion of the Rocky Mountains." Can Geol Sur. Ann Rpt. Pt D 1886 Schofield, S.J. "The Geological Record of the Cordillera in Can. Trans Roy Soc of Can. Sec IV. pp 79-103 1923 Schofield, S.J. •The Geology of the Cranbrook Map Area, B.C." Can Geol Sur. Mem 76 1915 Schofield, S.J. "The Geology and Ore-deposits of Ains-worth Mining Camp, 3.C." Can Geol Sur., Mem 117. 1920 Schofield, S.J. "Reconnaissance in East Kootenay, B.C.* 1913 Can Geol Sur. Summ Rpt p 221A 201 Schofield, S.J» "Ainsworth Mining Camp and Reconnaissance 1914 in West Kootenay, B.C." Can Geol Sur. Summ Rpt« p 38A Schofield, S.J» "Relationship of the PrecamSrian (Beltian) Terrain to the Lower Cambrian Strata of Southeastern B.C.* Can Geol Sur. Mus Bull No 35. 19212 Schofield, S.J. •The origin of the Rocky Mountain Trench" Trans Roy Soc Sec IV p 61 1920 Schofield, S.J. "Elko to Kootenay Lake, B.C» Can Geol Sur. Guide Bookk, No 9 p 46 1913 Schofield, S.J. "The Origin of Granite, (Micropegmatite) in the Purcell Sills.* Can Geol Sur. Mus Bull No 2 Geol Series 1914 No 13 Spur. J. E» "Geology of Aspen District." U.S. Geol Sur. Monograph 31 p 115 1898 Suchert, C •Paleogeography of North America." Geol Soc of America. Vol XX p 427 1910 Wallcott, 0 •D. " Smith Misc Coll, Vol 57 p 1 1910 Wallcott, C .D. Smith Misc Coll, Vol 75 No 1 Walker, J.I t "Lardeau Map Area, B.C.* Can Geol Sur. Mem 161. 1929 Walker, J.F •Geology and Mineral Deposits of the Wind-ermere Map Area, B.C.* Can Geol Sur. Mem 148 1926 "West Kootenay Sheet* Can Geol Sur. Map 792 * -v M 'Sheep Creek Map Area". Can Geol Sur. Map 1068 1909 202 -TSé/eX \ Ì <1 * ) 11 m i f § t * 1 m 1 1 ^ H 1 1 1 1 1 Hl] ; S 4 Uv i iti i n i if! * í i l'i : i 11 ^ ^ ? 1 111 ill I i i 1 1 j. 1 i m i l * i ^ i <i 1 s Militili il î 1 1 1 1 < 1 * 1 1 i , itili Ì 1 t * t « t 4 § -S N ^ 1 1 V 1 t ä 1 1 1 ^ I * t-ï 1 j i Ì i Il 1 1 I 1 3' ^ * ^ ^ •S * 1 <1 5 1 i § i * 1 * t, 1 -V S ^ 1 ^ Â S 1 î 1 N S 1 1 < 1 1 il 4 i i 1 1 s \ ^ i l l J 1 Ì 1 i 4 i sis ? Si 41 ^ Ä À m 1 1 1 1 i i * i i i î i ? i 1 i i i 1 i i S 1 * £ « 1 « 1 ! 1 t i l l 1 1 ! 1 S •3 ; 04 o j/¡¿y (t/Oy/9gj !T~ TABLE 2 1 2 3 4 5 6 8 Si02 66.46 - 60.09 - 50.36 - 51.92 - 52.63 - 71.69 -IB" 41.50 — 70.78 Ti02 0.27 - - 0.90 - 1.83 - 0.62 - 0.59 - 3.33 — 0.20 A120 3 15.34 - 17.20 - 13.66 - 14.13 - 16.76 - 13.29 - 17.09 — 15.72 F e 20 3 1.68 - 6.73 - 2.22 - 2.97 - 2.86 - 0.83 - 3.31 — 0.36 FeO 1.83 - - 8.38 - 6.92 - 10.74 - 4.33 - 10.08 — 1.61 MnO - - 0.20 - 0.14 - 0.38 - 0.09 - Tr _ 0.03 MgO l.li - 0.47 - 8.67 - 8.22 - 4.33 - 1.28 - 12.78 _ 0.46 CaO 3.43 - 8.24 - 11.50 - 11.53 - 6.17 - 1.66 - 0.97 _ 1.92 SrO - - - - — - Tr BaO - - - - - - — 0.01 Ua20 4.86 - 2.45 - 2.54 - 1.38 - 1.41 - 2.48 - 2.84 — 3.48 K20 * .58 - 6.25 - 0.75 - 0.45 - 2.29 - 2.37 - 0.22 — 5.23 *2P5 0.08 - 0.07 - 0.04 - 0.33 - 0.33 - 0.07 - 1.08 _ 0.26 H20 plus 0.29 - - 0.05 - 0.10 - 0.12 - 0.14 - 6.99 _ 0.25 HpO minus' - - 0.71 - 1.07 - 1.17 - 1.31 - 0.21 0.10 CO 2 - - - - - — Nil CI - - - - — — s - _ _ Total 99.93 -101.41 SS.Ofi -TOO.78 99 .91 -100.1fi -100.36 -100,41 Some special ratios 1 2 8, K20 35.6 - 36.9 -32.7 Ka20 37 . 8 - 14.5 -49.2 CaO 26.6 - 48.6 - 18.1 Total 100.0 100.0 100.0 1) . Kelson Granite, specimen collected "by Brock. 2). Nels on Granite, sapjle "by Gwillim. 3). Hypersthene-ga'b'bro. 4) . Hornblende-gatfbro. 5). Quartz-diorite. 6). Gra/nophyre from Purcell sill. 7) . PureeJ1 Lava.. 8). Rykert Granite, specimen collected by Daly. TABLE g (cont) 9 10 11 12 13 14 15 16 SiO g 60.27 - 66.46 - 62.08 — 56.52 - 55.62 - 54.49 - 56.52 - 54.54 TiOg 0.63 - 0.27 - 0.73 - 0.60 - 0.88 - 0.70 - 1.00 - 0.96 AI2O3 17.17 - 15.34 - 16.61 - 16.66 - 15.64 - 16.51 - 16.96 - 18.10 Fe203 2.36 - 1.68 - 1.53 - 3.86 - 1.85 - 2.79 - 1.10 - 1.14 * FeO 3.67 - 1.83 - 3.72 - 3.55 - 5.63 - 5.20 - 4.51 - 4.63 MnO 0.14 - - 0.11 - 0.02 - 0.03 - 0.10 - 0.14 - 0.10 MgO 2.45 - 1.11 - 2.44 - 3.08 - 3.68 - 3.55 - 4.01 - 4.56 CaO 6.49 - 3.43 - 5.20 - 6.34 - 5.92 - 7.06 - 5.93 - 5.85 SrO 0.04 - - 0.03 - 0.24 - 0.14 - - 0.13 - 0.15 BaO 0.04 - - 0.09 - 0.09 - 0.11 - - 0.16 - 0.21 NagO 2.92 - 4.86 - 3.18 - 4.05 1.37 - 3.50 - 3.36 - 3.38 K20 3.25 - 4.25 - 3.26 - 4.46 - 3.56 - 4.36 - 4.46 - 5.44 P2O5 0.02 - 0.08 - 0.30 - 0,14 — - 0.20 - 0.31 - 0.46 H2O plus 0.23 - 0.29 - 0.60 - 0.16 - 0.35 - 0.07 - 0.11 - 0.10 H20 minus 0.15 - - - 1.00 - - 1.18 - 0.48 - 0.50 CO 2 - - - - - 0.10 - 0.34 -CI - - - 0.11 - 0.02 - - -S — — — 0.31 n.sn — - n.sa — Total 100.01 _ 99.93 -100.47 -100.63 -100.58 -100.04 -100.25 -100.12 Special Ratios 9. 12 11 12 11 14 15 16 K20 25.7 - 36.2 - 28.2 " 30.0 - 54.1 -• 29.2 - 32.4 - 37.2 NagO 23.0 - 37.6 - 27.2 - 27.3 - 8.6 -•23.4 - 24.4 - 23.2 CaO 51.3 - 26.2 - 44.6 - 42.7 - 37.3 -• 47.4 - 43.2 - 39.6 Total 100.0 -• 100.0 -• 100.0 -• 100.0 -• 100.0 -•100.0 - 100.0 - 100.0 9) . The Ba^yonne hatholith, specimen "by Daly. 10). The Sa^-lmon River llonzonite. 11). The Trail hatholith. 12). The Trail "batholith. 13). The Diorite porphyrite. 14). Fresh gra^nula^r monzonite. 15). An avera^ge of four augite latifces. 16). The Augite latite. TABLE 2 (cont) 17 M 11 20 21 .22 23 24 Si02 62.59 - 52.38 - 50.66 — 62*75 — 58.47 — 77.09 - 55.90 - 57.32 Ti02 0.54 - 1.10 - 1.32 - 0.60 - 0.60 - 0.05 - 0.90 — 0 .88 AI2O3 17.23 - 15.29 - 16.91 - 16.17 - 16.60 - 13.04 - 15.52 — 17.27 Fe203 1.51 - 2.99 - 1.71 - 0.28 - 1.57 - 0.82 - 1.22 — 1.62 FeO 2.02 — 5.53 - 6.17 - 5.58 - 5.45 - 0.26 - 5.22 — 5.94 MnO Tr - 0.10 - 0.16 - 0.06 - 0.05 - Tr - 0.08 - 0.09 MgO 1.30 - 5.84 - 5.50 - 1.76 - 2.41 - 0.12 - 4.70 - 2.68 CaO 1.99 - 7.30 - 8.26 — 5.50 - 5.64 - 0.65 - 5.79 - 4.24 SrO — 0.15 - 0.08 - 0.25 - 0.05 — Nil - 0.09 - 0.06 BaO - 0.25 - 0.25 - 0.19 - 0.19 - Nil - - 0.24 Na20 5.50 - 5.68 - 2.89 - 5.74 - 4.60 - 5.11 - 2.89 - 4.52 K20 6.74 - 5.84 - 4.45 - 5.11 - 5.73 - 4.50 - 4.45 - 5.96 P2O5 0.11 - 0.75 - 0.75 - 0.14 - 0.29 - 0.10 - 0.46 - 0.51 H20 plus 0.30 - 0.21 - 1.06 - 0.45 - 0.45 - 0.10 - 1.40 - 0.47 H20 minus - 0.63 - 0.14 - - - - 0.60 - 0.08 ce2 Tr - - - - — - 0.14 - 0.20 CI Tr - - - 0.15 - 0.02 - - -S Tr — — - 0.08 — 0.24 — — -Total 99.83 -100.04 -100.45 -100.50 -100.54 - 99.82 - 99.36 99.88 Special Ratios il- 18 l i 20 ¿1 22 24 -K20 47.4 - 25.9 - 28.6 - 36.8 - 55.9 - 54.6 - 33.8 _ 40.5 Na20 38.6 - 24.7 - 18.4 - 41.4 - 28.8 - 37.8 - 22.0 _ 30.7 CaO 14.0 - 49.4 - 53.0 ~ 21.8 - 35.5 - 7.6 - 4A.2 - gs.8 Total 100.0 - 100.0 - 100.0 - 100.0 - 100.0 - 100.0 - 100.0 - 1QQ.Q 17). The Coryell hatholith. 18). The Coryell hatholith. 19). The Salmon river raonzonite. 20) . The Sheppa-rd granite porphyry. 21). The Sheppard granite, summit of Lake Mountain. (Drysdale) 22). The Sheppa-rd Granite. (Daly) 23). The Augite porphyrite. 24). The Pulaskite porphyry. > o M EH O M tí tí o O ro • H •H tí -p -P CÌ tí i—! •H tí ra o > tí CD o rH iH cri O 1 >H c> •H O I—I o ü¡ r<q •p •P 10 O (1) ' "H tí K o CD tí to •H tí O! -d O © 0) 0> tí !> O -H ; f; -p •rH > •H -P O Lo ra fi o 0 co: tí o bn m M D3} < tí i—i o í\ -H (1) O n o A> ÍH ,'h a o •H -P tí tí •H O tí i-l O PH-H Q) ra C o CD ^ Ph P-1 C'j A o •H u. ? 57 •P tí •H H o CD fn ra tí o •rH K¡ ra +» S ?H CD tí -P _ o a CD •rH *H J-3 O *tí N Co •H CD O rH u *'H (Í FTÖ SH ra CL CD CD T>-tí -tí O •H -H M O co R¡ O •M CO Fi ÎH -P tí o •H to -P -IO T¡ o tí CD E; A H ° o J-3 tí -tí N c •rH CD O rH SH tí PH tí M ra ® © © M tí -tí O •H -rH ^ o tí o •H -P tí tí •H P CD tí CD pH P •rH C > -rH -P ü CO c Ci) ra o i—i rH ra •rH tí •rH •rH •P • O ra TÍ <D O ra •rH tí rH 3Ì O ti — ( u o o > i^ •P i. ,1 •H tí > •H •H Ti •P O O O cri i—1 «M O •rH tí O 1. i rH O rH -1 ítí o > ra p CD « •d ?H •H Lb * tí •rH Ö O 'H H-3 tí P * t í CD G >H CD to H tí S ÍH O o3 O d ra tí f5 1 rH tí CO tí rH O M ra O Cj •H o •p •H •P o tí ra +3 ra tí tí •p CD O •H -P o tí ra g U í> <+H tí -H o ó © tí •H O © -P •H -P «H o > o «H o O •H -p o tí a •H • HH tí tó a O •p -P tí O • t í (H M o tí tí N tí • t í tí •H © o •H O •H •H o o rH •"Ó O © tí -P o •P tí ra fe o •P •H tí cá tí rH •H •H Cj © tí -P o tí •H O ^ c3 O rH o c3 ra tí > ra o3 -t í tí •H © tí rH 1 l-H •H c3 •I-1 P-. •rH 5H tí CD u P-¡ •P rH o © ra a tí rH EH tí O > ra CD ra CD ?H f © ra •H o -r-o •H tí O CÖ d CD O tí o tí O •p © Cj ?H © fn rà rH O © - "1 ÍH rH rH ¡H 0 fn •H tí ^ tí © © O © ¡H © © O CO ra vi o CÍ3 M t 'H « r--í M O M « PH rn > O • ta © ra tí !+H tí O o -P O © «M •H © •H •P ÍH tí o ra o rH cá •H > -P © O • rH U o SH tí tí tí > tí tí •P tí •H tí ra u •P tí © bS) U o O co tí O •P O © © tí •H ti © ra ra © •H ü •H £ -d tí tí <H © +3 rH rH tí a CJ CÖ ra tí © tí © o © a tí Ö tí CD CD CD •H O o tí •H ra © • t í ra XI •H •ri •H fe tí tí fe a -tí ÎH O ÍH •H a •H rH tí O O CD © M • r t 1-1 tí «H •rH tí ra •tí tí tí tí «H .tí •H •H <H > ra tí © Cu O o - t í > o Pi tí tí O O tí O tí O -P -P -P O O c3 O O •H © ca tí o •H •H CD •H © ( - - - •rH tí CÖ ci g - t í O tí -P b.0 ra © © rH rH -P •P ra •P ra o l-H •P rH O tí tí N tí tí tí rH tí tí tí tí si tí © t>D tí tí tí m o •H O •iH •H o O © o O o CÖ o •H tí tí tí •H • t í tí -P & -P & En cá ^J •P •rH Ö o5 tí rH •rH •H •H > •H ÊtO •H tí > •H •H •H tí O tí tí o tí 5 O 0 -P oS -P o rH O cá ra tí P( -P •P JH -P © O tí O i>3 •H -P •H © © rH © rH m Ul tí cS •Ö CÔ •H Pí •H ^ tí CD ra CÖ -P cá © tí f • rH © u rH rH ¡>J <H ra a a rH •ri CÖ •tí ^ a rH •P O > W ra CD U u © > CÖ > a > •H rH tí P o tH ?H rH •H o •rH •rH tí U cá <D O tí o tí -P o - t í © © © ¿i © • t í tí © © tí tí •H S rH tH • t í • t í ,tí O rH iH fH <D ^ •H tí SH •H •H ÍH rH tí rH © rtí © •H tí O Pí © © CD ra © ra fe Ci3 H M PM M S M O M tíJ W en f=) LO CO m O t- i O PR t-i ¡=> líi CO M • i> » -P • © ra ra ra i» fn tí •H λ rH rH CD cá > -t í © rH rH CD ÎH tí •H © > ÍH © © tí cá Pi fH tí © tí © o O CD CD •H P< tí u tí r* tí h h H O to o rtí •rH tí tí •H tí •H Ö tí © B tí o V • t í •H •H O ra tí tí tí tí o O tí •rH S PH PH -p ci •H ra ra cá 03 •H •H O •H •H •H •H rH u CO •r- g ra ra <H •H -t í tí -t í u 0 > h rH © u fH •rH g cS ci CÖ ra tí O tí tí o O rg tí • t í © © CD f-u ÍH •H p ra O ¡» rH rH Ü • t í P( ö P4 & rH öS tí fn p •H $ © tí •H ti h tí •H •H p* O EH EH "-I g O O UÌ En O O S t=> 1-3 tí o •H ra o !H CD -P «H P) tí o •H -P tí -p tí CD •tí <D ra CD tí •H ÍH tí
Thesis/Dissertation
eng
Geological Sciences
Vancouver : University of British Columbia Library
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
Graduate
A survey of the general and economic geology of the east and south contact of the West Kootenay batholith
Text