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PJB Blommiw Munma: R. G. McComBix, Dmmr Mmirnu. GEOLOGICAL &JRVEY Na 7ft, Gmlooiqu. Siun Yoiir Mining Gamp, British Columbia GhMlM WalM ntytteto OTTAWA mi NftMt ^ CANADA DEPARTMENT OF MINES Hon. p. 1. BtoKom, Mimaru; It G. McComnu, Dv«n Mmwrs' GEOLOGICAL 8ITRVEY No. 76, Gboloqical Sunt Ymir Mining Camp, British Colun?bia av CaiarlM WalM Drytdato OTTAWA GovxiNiam PBiimNG ButiAU 1917 N&1651 ^^^ CONTENTS CHAPTER I. PAOC Introduction 1 General statement 1 Field work and acknowledgments 2 Situation 2 History 2 Previous work and bibliography 3 CHAPTER n. General character of district 7 Topography 7 Regional ^ Local 8 Physiographic considerations 9 Climate 10 Flora and fauna 12 CHAPTER HI. General geology 1' Introduction 1" Table of formations 19 Description of formations 21 Palaeozoic 21 Lower Cambrian or Pre-Cambrian 21 Summit series (in part) 21 Distribution 21 Lithology 21 Structure 22 Origin 22 Age and correlation 23 Poet-Cambrian 25 Pend-d'C)reille group 25 Distribution 25 Lithology 25 Structure 26 Origin 26 Age and correlation 26 PAGB 27 Mesozotc Triassic (?) *' Hallseries :f^ Distribution *° Lithology 28 Structure j° Origin, age, and correlation 28 Augite porphyrite sills, flows, and pyroclastics 29 Distribution 29 Lithology ^^ Structure and origin 30 Age and correlation 31 Jurassic Granite porphyry tongues ^* Distribution ^2 Lithology ^^ Structure and origin 33 Agp and correlation 33 Nelson batholith, stocks, and tongues 33 Distribution 34 Lithology ^* Structure ^° Origin 36 Age and correlation ■'° Monzonite chonolith 36 Distribution 36 Lithology 37 Structure and origin 37 Aee and correlation 38 38 Cenozoic Tertiary 'f" 01igocene(?) f Salmon River monzonite stock •*° Distribution 38 Lithology 38 Structure and origin 39 Age and correlation 39 Pulaskite *° Miocene ( ?) ■*" Syenite porphyry, granite porphyry, and younger lamprophyre dykes ^ Quaternary Boulder clay or till • *J Fluvioglacial alluvium and stream deposits 41 Geological history Summary of geological history CHAPTER IV. PAGE Economic geology ^ Introduction ^ Ore occurrence *^ Types of ore deposit *7 Fissure vein ore-shoots cutting formations 47 Fissure vein ore-shoots and pockets, strilcing with formations 52 Replacement ore-shoots in limestone S3 Character of ores and gangues 53 Ores 53 Gangues 54 Mineralogy 54 Native elements 55 Gold 55 Silver 55 Sulphides 55 Pyrite 55 Galena 55 Sphalerite 56 Chalcopyrite 56 Pyrrhotite 56 Tetrahedrite 56 Arsenopyrite 56 Molybdenite 56 Oxides 56 Quartz 56 Limonite 57 Wad 57 Phosphate 57 Pyromorphite 57 Carbonates 57 Calcite 57 Cerussite 58 Malachite 58 Azurite 58 Silicates 58 Tremolite 58 Epidote 58 Chlorite 58 Serpentine 58 Kaolin 58 Origin of ore deposits 59 Age and correlation of ore deposits 61 Present status and future of dbtrict 62 CHAPTER V. FAOB Description of mines and prospects <»* Introduction "* List of properties ^ Wild Horse creek and South Fork belt 61 Blackcock 67 Canadian Pacific Commodore Foghorn 68 68 69 73 74 75 75 Good Hope H Roanoke Sterling Wilcox Location Transportation ^^ Topography ^^ Water supply, timber, and climate 76 History ^^ Production ^^ Mine development 7' Geological structure '' Geology of mine workings 85 Mining ^^ Milling 8^ Origin 87 Future work 88 Ymir Belle 89 Apex and adjoining claims 90 Black Diamond '^ Georgina '* Rosalia '^ North Fork, Wild Horse Creek belt 93 Alexandre and Uumas 93 Carthage 93 Elise '* Gold Cup 94 Goodenough and Surprise ^5 Jennie Bell and Ymir Mint Old Timer Summit Taniarac Ymir Location Topography ^^O History and development lOO % 97 98 98 100 100 V PACE Geology ^^^ \iining '"' Milling *05 XRay 107 Bear Creek belt ^•^^ Atlin-Nome 1°^ Canadian Girl 108 Dundee *^ Yankee Girl 112 Location "^ Development H^ Geology H^ Yukon 11* Porcupine Creek belt H*^ Hunter V H^ lowna 1'* Mulligan and Gold Queen ^20 Nevada 12° Union Jack and Empress 121 Big Four and Jubilee 122 New York Central 122 Porcupine 12^ Cristabell 123 Boulder Creek belt 123 Free Silver 123 May Blossom 12* Bimetallic 126 Bullion, Last Chance, and Ivanhoe 126 Quartz Creek belt 126 Golden Hem 126 Stewart Creek belt 127 Barrett Creek belt 128 Porto Rico 128 Location 12° Transportation 12° Topography *'° Timber 12' Water supply 12' History and production "" Geological structure "1 Geology of mine workings 13* Mining and milling "* Origin 135 Future work "6 Hall Creek belt 13^ Fern 13^ VI PACE Location 137 Transportation, timber, and water supply 137 History and production 138 Mine development 139 Mining and milling 139 Geological structure 141 Geology of mine workings 143 Origin 144 Future work 145 Gola King group 146 Bluestone, Clincher, Evening Star, etc 147 Clearwater Creek belt 147 Lost Cabin 147 Placer mininp 148 Add-Jida 149 Index 177 List of publications. , ILLUSTRATIONS. Map 175 A, No. 1594. Ymir, Kootenay district, B.C., topography and geology '" pocket Plate L Town of Ymit, 1914 Frontispiece IL Southeast slope of Wild Horse valley showing glacially bevelled spurs 1^3 IIL FoHatio. in Pend-d'Oreille roof pendant 155 IV. Hall series squeezed conglomerate 157 V. A and B. Coarse volcanic agglomerate from the west slope of Elise mountain 159 VI. A and B. Injection phenomena at granodiorite contact 161 VII. A. Glory hole at Hunter V mine. B and C. Porphyritic granite on Foghorn trail 163 VIII. Ymir mill in 1914 165 IX. A. Green timber, Ymir 167 B. Brfll* or burnt country, Ymir 167 X. Salmon River monzonite stock 169 XI. Block diagram of Ymir mine, mill, I id cyanide plant 171 XII. Block diagram of Ymir vein and geologl.idl structure 173 XIII. Stope in Ymir mine 1^5 XIV. A. Panorama from Hunter V mine 176 B. Panorama from Gold Cup property 176 XV. Panorama from Elise mountain 1'6 Figure 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. n. li. 14. IS. 16. vii rAOB Index map showing position of Ymir map-area 8 Block diagram showing localization of ore-ihoots at dylce intersection ** (No. 1631) Block diagram of curving Tamarac fissure vein SO Complex fissure vein at Foghorn mine SI Mineral claims in the vicinity of Ymir 65 (No. 1632) Steieogram of Wilcox mine 76 Vein structure at Wilcox mine. 8* Plan and section of Ymir mine 103 Flow sheet for Ymir Mine ore, Ymir mill and cyanide plant 106 Plan and sections of Dundee mine lU Plan and section of Yankee Girl mine US Plan and section of lowna mine 11' Plan and sections of May Blossom mine 125 (No. 1633) Stereogram of Porto Rico mine 132 Plan and section of Fern mine 1*0 Transverse section of Fern vein, diagrammatic 142 Ymir Mining Gamp, British Columbia. CHAPTER I. INTRODUCTION. GENERAL STATEMENT. Ymir' gold camp forms a part cf Nelson mining division of West Kootenay district, Britisfi Columbia. Of the eight divisions in West Kootenay district Nelson ranks third as a metal producer. West Kootenay district for the past two decades has been closely contesting with the Boundary district for the position of chief producer of metals in the province.' The total production of the two districts since 1894 exceeds $200,000,000 of which more than 8127,000,000 is credited to West Kootenay. From 1905 to 1913 the Boundary district led in production and in 1906 exceeded by over $500,000 the maximum production of West Kootenay district for any one year. Since 1913 the production of the Boundary district lias fallen oflf and at present West Kootenay district leads the province in metal output. Although Ymir is one of the oldest lode mining camps in British Columbia and the Ymir mine was at one time the largest gold mine in Canada, very little geological work has been done there since the investigations of McConnell in 1897.« The present report gives the results of later field work carried on during August and September, 1914. I In old Norse mythology the name Ymir was that of the progenitor of the gi«nti who not through the interworking of heat and cold in the primeval abyss. Ymir was slain by Odin aiid his brothers Vili and V« and out of his body they created the world. Ymir's flesh became the land, his bones the mountains, his blood lakes and streams, his hair the forests, his skull the hr- yens, and his brains the clouds. « For statistics of production see Reports of the British Columbia Bureau of Mines. > Geol. Surv.. Can., Sum. Rept., 1897, pp. 31-32 A. FIELD WORK AND ACKNOWLEDGMENTS. The area mapped is about 145 square miles in extent and includes the mineralized zones lying south of Hall, east of the crest of the Nelson (Quartzite) range, and north of Salmo. The west boundary of the area is 5 miles west of the Nelson and Fort Sheppard railway and includes the Fern and Porto Rico mines. Ir the field work W. J. Gray rendered able assistance. Indebf ness is grateiully acknowledged to the owners and superintendents of the various properties for their interest and aid in the progress of the work. SITUATION. The town of Ymir (Plate I) — the centre for the gold camp of the same name — is situated on the Nelson and Fort Sheppard railway, 27 miles south of Nelson and 7 miles north of Salmo. It is about 20 miles north of the International Boundary and 172 miles from Spokane, Washington, via the Great Northern railway. The accompanying index map (Figure 1, page 8) shows the position of the Ymir map-area with respect to neighbouring mining camps in West Kootenay and Boundary districts. HISTORY. In 1885 two brothers named Hall, who two years later discovered the Silver King mir at Nelson, made locations near the headwaters of Wild Horse creek. This creek was worked to some extent for placer gold 'n the early days. The Nelson and Fort Sheppard railway, constructed in 1893, made the district more easily accessible and in the summer of 1895 the Rockland, Ymir, and Mugwump claims were located. It was not until the summer and autumn of 1896, however, that prospectors who had been attracted by the mining boom at Rossland, began to pay attention to other districts. It was then that mining really commenced at Ymir and among the many claims that were staked i' >6 were the Free Silver, Elise, Dundee, Summit, Sterling ^ckcock, Good Hope, Tamarac, Foghorn, Wilcox, and Porto J. In 1897 the Fern mill was installed and the Ymir and Porto Rico properties were being energetically opened up. Development was also being done on the Dundee, Wilcox, Porcupine. New Brunswick, Union Jack, Jubilee, Roanoke, Tamarac, and other properties. In 1898 the camp began to attract widespread attention, the population of Ymir town increased to 1,000 people, and the pay roll exceeded $20,000 a month. The Ymir, Fern, and Dundee mines were being rapidly developed and several concentrating plants wer installed throughout the district. In 1899 irine development was impeded by labour troub'°s and in 1900 and 1901 by a general mining depression due to labour trou'ules at Rossland' and other causes. Mining conditions improved in 1902 and the Ymir, Yellow- stone,* Wilcox, Arlington,' Fern, Tamarac, and Spotted Horse properties produced ore; the total production aggregating, approximately, 80,000 tons. Most of the ore mined was treated in local stamp mills. The average monthly production of the Ymir 80-stamp mill was at that time 6,000 tons, and that of the Fern 10-stamp mill v 3 750 tons. In 1903 the Ymir mine ran into lower grade ore and mining and milling operations were not so profitable. The Hunter V mine commenced operations in 1903 and in 1904 shippet' ore in the crude state to the Hall smelter at Nelson. The Ymir, Wilcox, Fern, and Porto Rico mines continued to treat ore at their own stamp mill*. About this time developments in the neighbouring Sheep Creek gold camp overshadowed niinirj operations at Ymir. The Ymir camp may be said to have had a comparatively steady growth though many of the properties in operation ten years ago have been worked only intermittently since then and others have been abandoned. PREVIOUS WORK AND BIBLIOGRAPHY. The first geological work in the Ymir camp was done in 1897 by R. G. McConnell, now Deputy Minister of Mines, in connexion with the preparation of the West Kootenay map- sheet. In 1902 and 1903 R. A. Daly, geologist to the Boundary > "Oology and ore depotiu of RoMland", Gtol. Surv.. Can.. Mem. 77, p. 11 and 6g. 2, p. 13. > Thete propertiet are ouuide the Uniu of the Ymir map-area. CommiMion. examined a S-mile belt alonR the International Boundary and in hi. report dewrribe. the southern extensions Of many of the formations found outcropping within the limits Of Ymir map-area. During the field seasons of 1910 and 1911 u 'f ^"y-"/,**'*' (Geological Survey staff, mapfi^tl and reported on both the Nelson and Sheep Creek map-areas, the former adjoinmg the Ymir map-area to the northwest and the latter to the southeast. The following bibliography contains the main articles and references bearing on the Ymir mining camp, arranged chronologically. 1894. MrConnell. R. G.. (icol. Surv.. Can.. Sum. Kept. 1894. p. 3SA Describes visit to Fern mine. Hall cretk. 1896. McConnell. R. G.. Gcol. Surv.. Can.. Sum. Rept. 1896. pp. 18- 30A. RecoL.iaissance work in region. Carlyle. W. A.. Bull. No. 3. Bureau of Mines. B.C., p. 75. Des- cribcs Fern group of claims and Nelson mining division. 1897. McConnell. R. G.. Cm-oI. Surv.. Can.. Sum. Rept.. pp. 31-32 A Describes Ymir, Dundee, and Porto Rico mines. Minister of Mines. British Columbia. Annual Rtpf,rt 1897. p. 1899. British Columbia. Annual Report 1899. Minister of Mines, pp. 691-692. 1900. British Columbia. Annual Report 1900. Minister of Mines, pp. 838-843. Fowler, S. S., "The Ymir mine and its mill practice," Jour Can Min. Inst., 1900, pp. 3-10. 1901. Mining Recora, British Columbia, vol. VIII, pp. 65-135 203 239, 273, 340, 384. 1902. Daly R. A., Gcol. Surv., Cai.., Sum. Rept., pp. 144-147A Geological work at International Boundary. Mlni»tcr of Minin, BritiHh Columbia. Annual Report 1902, pp. 158-161. Minii.M Riford, British I'olumbiii vol. IX, Ymir Daly, R. A.. "The nomenclature of the North American Cordillen between the 47th and S3rd paiallela of latitude." Geog. Jour., toI. 27. 1906, pp. 586-«0«. 8 Local. As may be seen on the index map (Figure 1) Ymir map-area includes both the west central portion of the Nelson (Quartzite) range and the east central portion of the Figure 1. Index map showing position of Ymir map-area. Bonnington range. The two mountain ranges are separated by the deep, flaring valley of Salmon river which flows in a meandering course southward through the centre of the area. This river drains virtually the whole district and empties into Pend-d'Oreille river near the International Boundary. The highland areas of Ymir district range in elevation from 5,000 to 6,000 feet above sea-level and have slopes grading gently toward the main valleys. The valleys, with their steep, heavily-timbered sides, trench the upland areas to depths varying from a few hundred to 2,000 feet. Surmounting the gentler highland topography, particularly toward the eastern and western borders of the map-area, occur high mountain peaks and serrated ridges. The highest mountain in the district is Mount Baldyi which lies along the axis of the Nelson (Quart- zite) range and attains a height of 7,660 feet above sea-level. The transition fr i highland to lowland topography, although generally very gradual, is pronounced in certain localities and m; ^d by prominent topographic shoulders or unconformities.' jlacial forms, including cirques (Plate XV), aretes, trough- shaped valleys (Plate XIV A), truncated spurs (Plate II), hanging valleys, roches mountonees (Plate XIV B), and valley terraces are prominent topographic features in the landscape. The influence of bedrock structures upon the topography may be observed in many places. Strike ridges and depressions are of common occurrence and areas underlain by certain sedi- mentary and igneous rocks, display characteristic forms by which they may be recognized and traced for great distances. PHYSIOGRAPHIC CONSIDERATIONS. The physiography of the Selkirk mountains is complicated and much additional field work is required before safe inferences can be drawn and a connected account given of the probable origin and physiographic history of the Ymir landscape. The physiography of the Selkirks appears to have many points in common with that of the bordering Purcell and Columbia > Also known as Marble mountain from the white quaruite of which it is composed, which RKmhIes marble at a distance. .ndicative of a more than one erosion cycle physiographic development. 10 systems.' A detailed study of this physiographic province and Its relation to bordering provinces should make clear many obscure points in the life history of this section of the Cordillera- but theoretical problems of this kind do not fall within the scop^ of this memoir which is devoted primarily to a study of the ore deposits. CLIMATE. The Ymir district has a most agreeable and healthful climate. The cold in winter is not extreme, a 'though there are short periods when the thermometer drops considerably below zero (Fahr.), and the summers as a rule are temperate and dry with cool nights and moderately warm days, the thermometer c-casionally rising 80 or 90 degrees in the shade. Farm lands m the district do not require to be irrigated as the annual pre- cipitation amounts to nearly 30 inches, a large part of which falls as snow in the winter months.' The snowfall at Ymir varies from 2 to 4 feet per annum, the heaviest fall being in Janua/y. Mr. R. F. Stupart, director of the Dominion Met' ogical Service, has kindly furnished the following summary of meteoro- logical observations at Nelson, 15 miles north of Ymir as well as a summary of records made at Fruitvale on Beaver creek about 22 miles southwest of Ymir. The first table gives the monthly, seasonal, and annual means and extremes of temper- ature and precipitation from September 1898 to June 1901 and from January 1904 to December 1913. Schofield, S. J., "( 1915, pp. 160- Drysdale, C. W., " n, 1915, pp. 1 • Ten InchM of mow equals approximately one inch of rain. **°fl'M ^' •';'«2f°'°*^ "' Cranbrook map-area". Geol. Surv., Can., Mem. 76. 1915, pp. 160-169. ^^^f^i^'^ ^" "?~'°*y *°^ °" *'"^t«"t« o^ Rossland". Geol. Surv.. Can.. Mem. '• 'Vl3, pp. 175~188. 11 •At 1 1 i 1 15 3 2-54 3-35 2-31 O 00 1-64 1-29 217 o ? •- (Ml*- 2| 3 •n'i'6 1 — fM — i in — 00 r- 1 o e 2 § " tt is SrSS 666 o — — »«■ 3 O lnO^ vO "t- — 6 O r* 0> lO «»■ -o 2 666 O, r*: lO — — 6 f^ — 6 mO — 00 ■t 00« 100 » 1 oor-iO OOtNO &j,^ m ^i^ osom 666 30 — — 6 — oi •* S8S t^M — C^ r^ r^ r^ rg I/) Temperature i^iii 7 1 T •'^a 'C **> t^ — 1 t3iJi ??::? •*• vO t - 00 OC o o^ o* s 1 sO w^ O O s 0-< t— 'IT- "J t lO OOvoO oio *o in • J3 I 2 i £ a c IJ ^1 c c T c < > 'u Q a c > < 12 Year MtteoTotogical Obtenalions Taken at FruitvaU, B. C. Oct Jan. Feb. Mar. Apr. May J.ine JulyiAug. Sept. Nov. Dec. Mean Temperature 1910. 1911. 16-2 19-339-948-3552 22-4 3S.4,43-7 49.5 57.3,64-3 59- 0,62 -9 58-0 58-5 53-64S-4 34-3 29-3 Rainfall 1910. 1911. 014 000|000 1-62 0-65 1 091. 69 I 0-32;3.65 217 203 069 0-69 0-80 1 02 1- 19,2.92 3-76 018 Snowfall 1910 20. 1 15-6 9-3 3-2 4-5 OC 4-9 1 1 4-233-2 1911 |-...|.... FLORA AND FAUNA. The Ymir area was once heavily forest-covered, but the reserves have been considerably depleted by fire and to furnish wood for the mines. The burnt areas or brfll^s are covered with scrubby second growth excepting where they have been recently re-burned and are now grown over with fireweed (Plate IX) There are, however, some good areas of green timber still left. The Nankm Pole and Post Company are probably the largest lumber operators in the district and have under lease about 5.300 acres of timber lands on Clcar^v-ater. Hall. Barrett and Poreupme creeks. Timber limits on Stewart creek are also bemg worked by another company. The forest is principally coniferous and made up mainly of the following trees: cedar' {Thuya pltcata), hemlock {Tsuga heterophylla) , white fir or balsam (Abtes lasiocarpa), white pine {Pinus monticola), spruce ' Chiefly in tlie valley botConu. • CWefly on high mountain sloixs and benchea. 13 (Picea Englemanni), tamarack {Larix americana), scrub or jack- pine {Piniis Murryana), Douglas fir (Pseudotsuga mucronata), and red pine' {Pinns ponderosa). Other trees of common occur- rence are the pc^plar or aspen (Populus tremuloides), the cotton- wood (Poptilus balsamifera var. candicans), the birch {Betula occidentalis), and a small maple {Acer Douglasii). Ground hem- lock or yew {Taxus hrevifolia), mountain laurel or "buck brush," rhododendron {Rhododendra albiflorum), willows, and ciders grow in damp ravines and in the shade of the larger trees and render travel on many of the ridges and valley sides slow and tedious. W. C. Sandercock, a member of the field party, collected about 150 species of plants within the limits of the map-area, during August and September. These were submitted to J. M. Macoun of the biological division of the Geological Survey who reports on the collection as follows: POLYPODlACE.e. ,,..,,.. »23S Polypodium occidtntale (Hook.) Maxon. Phegopteris alpestris (Hoppc) Mett. „ DryopUris (I..) Fee. 139 10 214 156 113 307 82 301 305 234 81 190 147 11 233 221 13 Adiantum pedatum L. var. aleuttcum Rupr. Cheilanlhes Fefi Moore. Cryptogramma densa (Brack.) Diels. „ acrostichoides R. Br. „ , (Kootenay river). . . . , AspUnium Trichomanes L. (North of river across Taghura bndge.) Athyrium cyclosorum Rupr. Polystickum Lonchitis (L.) Roth. „ Braunii (Spenner) Fee var. Aspidium Filix-mas (L.) Sw. „ spinulosum (O. F. Muller) Sw. var. dilatalum (Hoffm.) Hook. spinulosum (O. F. Muller) Sw. \ar. dilatatum (Hoffm.) Hook. Cystopleris Jragilis (L.) Bernh. Woodsia oregana DC. Eaton. OPHIOGLOSSACE^. 200 Botrychium silaifolium Presl. LVCOPODIACEjE. 322 Lycopodium annottu^m L. 58 „ clavatum L. ' Of tare occurrence in the Vmir district. •The numbers used in Oiis list are Mr. Sandercock's field numbers and are retained here I his field notes are also so numbered. 14 TAXACEA. 14 Taxus brtvifolia Nutt. riNACEA. 326 Pinus ponderosa (Dougl.) Lawion (Cottonwood creek). ■""' Murrayana Ball. 327 203 232 monticola Dougl. 209 Picea Entelmanni Party. 30 , „ , 19 Thuja pticala Donn. GKAUINEK. 212 Festuea HaUii (Vasey) Piper. CYPERACE*. 180 Cartxf estiva Dew. JUNCACEA. 181 Juneus Mertensianus Bong. 179 , ensif alius Wika. var. major Hook. 222 Lutula glabrata Desv. LILIACEX. 77 Xerophyllum tenax (Pursh.) Nutt. 155 Zygadenus tenenosus VVats. 120 Veratrum viride Ait. 304 Allium cernuum Roth. 148 Erythronium grandiflorum Pursh. 64 Clinlonia unifolia (Schult.) Kunth. 9 Smilacina sUllata (L.) Desf. OKCHIDACE.E. 51 69 Epipaelis decipiens (Hook.) Ames. Corallorhiza maculata Raf. SALICACE.e. 227 Salix Barclayi Anders. BETULACE.E. 61 Corylus californica (A.DC.) Rose. 20 Alnus tenutfolia Nutt. ARISTOLOCHIACEj£. 105 Asarum caudatum Lindl. mSM 13 rOLYCONACBX. 136 Oxyria digyna (L.) Hill. 65 Rumex AcetostUa L. (Introduced). 306 Polygonum Douitasii Greene. 124 Erioiofium htractoides Nutt. 145 , tubalpinum Greene. CBBNOPODIACEA. 193 Chenopodium Boirys L. (Introduced). 303 , capitatum (L.) A»ch. CARYOPHYLLACEiB. 132 Arenaria capillaris Poir. var. nardi/olia Kegel. 186 Silene Menmesii Hook. 144 , Douglasii Hook. var. mMlKavlts (Nutt.) Rob. PORTULACACEiB. 23 Claylonia parvifolia M05. 133 „ asanfolia Bong. RANUNCULACE*. 71 Ranuneulus Bongardi Greene. 226 , Eschscholttii Schlcct. 63 Thaliclrum occidenlule Clray. lis Pulsatilla occidentalis (Wats.) Freyn. 114 Clematis Columbiana (Nutt.) Torr. 6 Aetata arguta Nutt. 119 Aquilegia flavescens Wats. 16 Aconitum columbianum Nutt. BERBERIDACEiE. 93 Berberis repens Lindl. CRUCIFER^. 231 161 Arabis Lyallii Wats. Radicula obtusa (Nutt.) Greene. CRASSULACEiE. 121 Sedum stenopetalum Pursh. 220 n roseum (L.) Scop. SAXIFRAGACEiB. 228 Leptarrhena amplexifolia (Sternb.)'Ser. 134 Saxifraga bronchialis L. 140 « Mertensiana Bong. 230 , Bongardi Presl. 7 Tiarella unfoliala Hook. 97 Tellima grandiflora (Pursh.) Dougl. 96 Heuckera columbiana Rydb. 16 17 Pamassia fimbriata Koenig. 210 UiUUa ptntandra Hook. 196 PhiUtdelphiu Ltwihi Purth. ■OtACB.1. 224 Spiraa lueida Dougl. 201 Arunrus Sylvester Ki iformis Don. 126 Rhododendron allrifiorum Hook. ArOCYNACBiB. 25 Apocynum androsetmifMum L. POLEMONIACEvG. 137 Polemonium humile R. and G. BYOBOPHYLLACE;*. 86 Phacelia Uptoupala Rydb. lOKKAGINACEiE. 102 Merlensia ciliala Don. SCROFHULAUACEiE. 123 Pentstemon fruticosus (Pureh) Greene. 164 Veronica americana Schwein. 112 , serpyUi/oUa L. 22 Mimulus Lewtm Pur«h. 158 , nasutus Greene. 78 CasliUeja lanceifolia Rvdb. 122 Pedicularis racemosa Hook. 143 , froenlandica Ret«. CAFKIFOLIACEiB. 53 Linnaa borealis L. var. americana (Forbea) Rehdner. 99 Lonicera involucrala Banks. _ 49 Symphoricarpus racemosa Michx. 18 VALiaiAMACJ;!. 129 Vateriaiu nteViMM Bong. CAMPANULACBA. 75 CitmpaHida rolunditcUa L. COMPOSITE. 118 Aittr Engtlmannii Gray. . contpicuus l.indl. , foliaeeui Lindl. var. frondtus Gray. Ertneron acrit I,, var. , talsutinosus Gray. . fhiliuUi hicMt L. SottdatoUpida DC. var. Wtmfoto (Nutt.) Fernald. Arlemtsia dticolor Dougl. Arnica f n latifoliii Dong. S'necto canui Hook. . triiintularis Huok. Adenncnulon hicolor Hook. Anaphalit margarilacea Benth. llitracium Scouleri fiook. rrufjV* Hook. 116 2tH 21S 117 168 73 211 lOJ 128 149 321 74 45 127 110 (At mouth of Boulder creek.) (Up Uuuklcr creek.) Suppltmtntary List of Flowering Plants ColUcUd by W. C. Sandtrcock in the Imir Dislrtct, August, 1916. •^anaercocM in Lycopodium romptanatum L. '^"'f "/"«* amptexijolius (L.) DC. (Boulder creek). Trillium ovatum I'ursh. Lislera cordate R.Br. (Boulder Creek flati). IJabenana orbiculata Torr. (Boulder Creek flats) Sangiiisorba occidentalis Nutt. Rosa gymnocarpa Nutt. Lupinus Burkei VVau. Spharalcea rivularis Torr. Zitia cordata (Walt.) DC. Osmorriza divaricata Nutt. Moneses uniflora L. (Near Boulder creek. YmTr') Monotropa uniflora L. Mimulus Langsdorfii Donn. (In Ymir.) ^r«wWa tWgarn L. var. lanceolata (Barton) Fernald. i^oltdago Uptda DC. var. Wongota (Nutt.) Fernald CM«T" '"""'•^" <^""-' ^'*«n«- (Probably introduced from Cypripedium montanum Dougl. (Dewdney trail.) ZJryoi Drummondii Hook. « • Comatium nudicaule (Pursh) C. and R. " « The fauna of the Ymir district includes both mule and white-tailed deer, black, brown, and grizzly bears, coyote, ruffed and blue grouse, foolhen (Franklin's grouse), and ptar- migan, chipmunks, red squirrels, weasels, porcupine, beaver, pilM or httle chief hare«. wood rats, gophers. Humming birds and Stellers jay are also included in the fauna noted. The stream s are well stocked with brook trout. > Locally koowa ai rock nbfait. 239 24U 2 241 237 248 249 146 54 243 244 236 238 247 250 242 184 1 19 CHAPTER III. GENERAL GEOLOGY. INTRODUCTION. The West Kootcnay geological map' on which the geology of the Ymir district was first outlined by McConnell in 1896« furnished a good base for the more detailed economic work of the field season of 1914, and more recent work by K. A. Daly from 1902 to 1904 and by O. E, I.eRoy in 1910 and 1911 in neighbouring regions has thrown additional light on certain phases of the gtnjlogy. The enlarged scale of mapi)ing (1 mile to 1 inch) necessitated changing some of the geological bciundaries on the earlier map and made possible the separation of certain prominent formational members that had been grouped under the name Rossland Volcanic group. For instance, a thick series of sedimentary formations— the Hall series— was found on the eastern flank of the Bonnington Mountain range and has been mapped as a separate unit of the Rossland group. In the following table of formations the geological ages assigned to the different formations are tentative only, as fossil evidence is wanting. TABLE OF FORMAT lOyS. ERA. rERIOD. rOMIATION NAME. FORM A^'D LITHOLOGICAl. CUARACTEH. Recent. Stream deposits. Gravel, sand, silt, clay, soil, and subsoil. QUATERNARY Pleittocene. Stream deposits. Glacial deposits. Gravel, sand, silt, and clay. Boulder clay or till. TERTIARY. Miocene (?) Younger dyke*. Dykes and tongues of syenite porphyry, gran- ite porpnyry, and lam- prophyre. ■ G«ol. Surv.. Can.. Map No. 792, H04 (srale 4 miles to I Inch.) • CtoL Surr., Can.. Sum. Rtpt. U96, pp. lS-30 A. 20 TAP '•■ / RMA TIONS.— Continued. TERTIARY. Oligocene ( ?) MESOZOIC. Jurassic. PALEOZOIC. Triassic ( ?) ORMATION NAME. FORM AND LITHOLOGICAL CHARACTER. Salmon River monzonite. Monzonite Nelson granite. Granite porphyry. Augite porphyrite, and andesite. Hall ■a !Pend-d'Oreille Post-Cambrian i o'c group. Lower Cambrian or ,„ Pre-Cambrian. (« 'jt .ISummit series ■^.i] (in part). Stock of coarsely granu- jar monzonite contain- ing a small core of gran- ular pulaskite (Coryell). Chonolith of monzonite. Batholith, cupola stocks and tongues of granitic intrusive rock varying from granite to diorite and varying in texture from porphyritic granite to granite porphyry. Injection tongues which have been much altered and are in part schistose Sills, flows, and pyro- clastic deposits of domi- nantly augite porphyr- ite which are in part schistose. Continental deposits of conglomerate, sandstone (reddish), and shale (car- bonaceous). .Metamorphic sedimen- tary group of argillite, quartzite, quartz schist, andalusite schist, and siliceous marble. Metamorphic group of banded quartzite, metar- gillite, quartz-mica schist, anci massive white quartzite. a 21 DESCRIPTION OF FORMATIONS. PALEOZOIC. LOWER CAMBRIAN OR PRE-C\MBRIAN. Summit Series (t ;Mrt). The oldest formations found ir thL- area covced by the Ymir map consist of banded quar .- ^.n, quntz-rJca schists, metargillites, and massive white quartzite ouiciopping in a conformable series along the eastern quarter of the area and forming the high and rugged Nelson or Quartzite range. The regularity of bedding in the quartzite is well shown by belts of spruce which stand out boldly on the higher hillsides, owing to the habit of this tree of following the chist bands. This series is the upper portion of the Summit series of Daly's Bound- ary report.' Distribution. The western border of the Summit series extends from the source of Wild Horse creek, on the divide between the latter creek and Midge creek, southwestward down the upper stretch of Wild Horse valley to the bend below the Wilcox mine. Thence the contact follows the same southwest- ward trend crossing over to South Fork valley and the basin of Bear creek to the forks of Porcupine creek and thence o\'cr the divide between the latter and Hidden creeks at a low point about a mile east of the Hunter V mine. The series extends to the eastern border of the map-area and several miles beyond it before it is cut off by the Nelson granite. Lithology. The members of the Summit series are chiefly light grey to greenish-grey quartzitei interbanded with siliceous metargillites and quartz-mica schists. The rocks are much altered near the granite intrusions and display rusty weathered outcrops. The highest member outcropping in the area is a heavily bedded mass of snow-white to light yellow quartzite which forms the summit of Mount Baldy. The white quartzite on weathering breaks up into large heavy plates which give a ■ Gtol. Surv.. Can.. Mem. 38. pp. 141-159. 22 sonorous metallic ring when struck with a hammer. Ripple- marks and scalloped and pitted forms of unknown origin are found on some bedding planes. No feldspar was detected in thin sections under the micoscope, although shreds of sericite occur, cementing subangular and rounded grains of glassy quartz. The quartz grains are strained and fractured in places. Structure. The portion of the Summit series present in the northern part of the area appears to be the uptilted western limb of a syndinc which forms the Quartzite range. In the vicinity of Wild Horse creek it is sharply cut off by a large mass of Nelson granite. This granite farther south swings westward and intrudes the Pend-d'Orcille group and on this account a wider belt of the Summit series is found to the south. There it is in contact with and interfolded with the younger sedimentary group (Pend-d'Oreille). The axis of the syncline is a couple of miles east of Baldy mountain and may be traced to beyond the International Boundary. The western limb consists of alternating bands of Beehive schist and Ripple quartzite which are repeated on the eastern limb. The east boundary of the syncline is marked by a thrust fault which brings up the basal arkosic and conglomeratic members of the series to the surface (Dewdney or Monk, Wolf and Irene conglomerate formations). Roof pendants in the form of long wedge-like ribs of much altered Summit series occur within the eastern granite masses. Origin. Owing to numerous granitic injections the Summit series is so poorly developed and fragmental that it has not been possible to collect sufficient diagnostic data to enable a con- clusion to be drawn as to the origin of the sediments or the topographic and climatic conditions under which they were fo.iiied. Recent work in the same formations elsewhere by Daly and Schofield have led them to infer that the sediments were laid down in a shallow continental basin disconnected with the ocean and containing fresh or brackish water. The climatic conditions alternated between humid and arid and the water in the basin was shallow enough at times for the formation of ripple-marks and mud cracks. In other places eolian deposits of dune sand quartzite and loessic quartzite were laid down.* ' Daly, R. A., Geol. Surv., Can., Mem. 68, pp. 100-107. 23 Age and Correlation. McConncU referred this quartzite series to the Cambrian and i rrelated it with Dawson's Lower Selkirk scries' of the northern Selkirks. The upper portion of the Summit series has been tentatively referred by Daly to the Cambrian. As the Ymir quartzite members lithologically resemble most clopely Daly's Ripple and Beehive formations they may be assigned a Lower and Middle Cambrian age. Much more field work in the Nelson range is needed to confirm the strati- graphic sequence of formations and to correlate Daly's Summit series with Schofield's Purcell series in East Kootenay district. Schofield favours a Pre-Cambrian age for the whole Purcell series, while Daly refers only the lower portion of the series to the Pre-Cambrian or Beltian. For purpose of comparison the following abridged cor- relation tables taken from Daly's and Schofield's related work in adjoining areas is here presented. Correlation According to Daly.* SYSTEM. CHIEFLY MIDDLE CAMBRIAN. SUMMIT SERIES SELKIRK MOUN- TAIN SYSTEM. PURCELL SERIES CffiUR D'ALENE 'GALTON SERIES PURCELL MOUN- SERIES. IDAHO.' ROCKY MOUN- TAIN SYSTEM. I TAIN SYSTEM. Lone Star 2000 + ft. MIDDLE CAMBRIAN. Moyie 3400 + ft. Striped Peak 1000 + ft. JRoosville 1 600 + j Phillips 550 ft. Gateway 1850 ft. Beehive 7000 ft. Kitchen 6000 n ' allace 4000 ft. 3t. Regis 1000 ft. LOWER CAMBRIAN. Ripple 1650 ft. Dewdney 2000 ft. Wolf 1000 ± ft. Kitchener 1400 ± ft. Creston 3000 ± ft. Gateway 1 125 ft. jSiyeh ! 4000 ft. Revett 1200 ft. Burke 2000 ft. Prichard 1500 ± ft. Wigwam 1200 ft. MacDonald 2350 ft. Hefty 775 ft. • Recent field work by the writer haa forced him to the conduiioii that the chronological •equence of the rock» named upper and lower Selkirk and NUkonlith aeriei on the W«»t Kootenay map theet is the oppoaiu of that given. > Geol. Surv., Can., Mem. 38, 1913. p. 178. 24 Correlation Accordint to Daly. — CoiUinutd. •TSTKlt. SUMUIT SERIES FURCELL SERIES CCEUR D'ALENE CALTON SERIES SELKIRK MOUN- PVRCELLMOUN- SERIES. IDAHO. ROCKY MOUN- TAIN SYSTEM. TAIN SYSTEM. TAIN SYSTEM. BELTIAN. Wolf 1900 ± ft. Monk 5500 ft. Irene volcanics 6000 ± ft. Irene conglo- merate 5000 -1- ft. Creston 6500 ± ft. Base concealed Prichard tlM + ft. Base concealed Altyn 650 ft. Base concealed Unconformity. Pre- Beltian 'Priest River ' terrane. Correlation According to Schofield.^ CAMBRIAN. Lowest Mi Idle Cambrian. Unconforrnity. Erosion surface. Gateway 1000 ft. Roosville 1000 ft. Phillips 500 ft. PRE- cambrian (beltian). Gateway 2025 ft. "■'r-ell lava. b,yeh 4000 ft. Erosion surface. Striped Peak 1000 ft. Purcell lava. Siyeh 4.000 ft. Kitchener 4500 ft. Wallace 4000 ft. Wigwam 1200 ft. MacDonald 2350 ft. Hefty 775 ft. Altyn 650 ft. Creston 5000 ft. St. Regis 1000 ft. Revett 1200 ft. Burke 2000 ft. Aldridge 8000 ± ft. Prichard 8000 ft. > Gcol. Surr., Can., Mem. 76, 191S, p. 52; 18 and 17. alK> Mui. BuU. No. 2, Gtologkal aeiiM, Not. 2S From the above tables it may be noted that Schofield correlates the Creston quartzite of the Purcell series, which lithologically most resembles the Ripple quartzite of the Summit series, with the St. Regis, Revett, and Burke formations of the Coeur d'Alene series. If this correlation is correct the Dewdney and Wolf formations of the Summit series may be correlated with Schofield's Aldridge formation, and the basal Irene and Monk formations of the Summit series be considered to represent the base of the Belt terrane in Canada. Further stratigraphic work is necessary in the Quartzite range between Ymir map-area and Daly's section, to properly clear up this problem of Pre-Cambrian and Cambrian cor- relation.' POST-CAMBRIAN. Pend-d'Oreille Group. The metamorphic group of dark coloured argillite, quartz- mica schist, andalusite schist, and siliceous marble named by Daly the Pend-d'Oreille group and referred to the Carboni- ferous (?) or Ordovician (?) period is of later age than the Summit series. Prior to Daly's work, the same group of for- mations had been referred to the Lower Cambrian* and cor- related with Dawson's Niskonlith series. Although diligent search was made for fossils in the Ymir field, none were found and the age of the group is still in doubt. Distribution. The Pend-d'Oreille group occurs through the central portion of Ymir map-area, extending from Clearwater creek southward through the valley of the North Fork of Wild Horse creek to the Dundee mine and the town of Ymir where it is cut off by the main granite mass. The group appears again east of the granite and extends in a narrow belt to the Hunter V mine and thence to Hidden and Sheep creeks where it has a greater width. Lithology. The Pend-d'Oreille group in Ymir district consists chiefly of metamorphosed sedimentary rocks including ^rhi^theWW fieW «»» the writer found Pott-Cambrian (Ordovician at baK) fo«Ui in the northern extenilon of thi» belt in the Slocan d'stnct (memoir m preparation). 26 dark argillaceous and arenaceous members which are altered near the granite to andalusite and mica schists. Phyllites, metargiUites, impure quartzites, altered tuffs, and siliceous marble are present in certain localities. The marble is fine grained and completely recrystallized. Greenstone occurs spar- ingly in the group throughout the area. Structure. The strike of the rocks, as a rule, conforms to the north-south trend of the border of the granite masses; the dips are steep and chiefly to the west although easterly dips are present in certain localities. The formations are generally sheared, mashed, crumpled, and to a minor extent faulted, so that their primary structures are very difficult to interpret. The Pend-d'Oreille schists, where surrounded by granite, are severely foliated, crumpled, and crenulated (Plate III). The present structure is komodinal^ in which the Pend-d'Oreille group occupies an intermediate position between the older Summit series and the younger Rossland group. Origin. It is inferred that the rocks of the Pend-d'Oreille group were laid down in a shallow continental sea, probably an arm of the Pacific ocean which periodically transgressed the low, lying Cordillera of Palaeozoic time. In this sea, mud, sand, and lime rocks were deposited, the limestones representing the offshore deposits and the carbonaceous argillites and sand- stones the inshore deposits. Marine sedimentation was inter- rupted at intervals by volcanic activity which resulted in the accumulation of volcanic dust in a few localities and elsewhere in the outpouring of lavas. Age and Correlation. No fossils were found within the area so that no definite age determinations could be made. The group has been called the Niskonlith series on West Kootenay map and correlated lithologically with Dawson's series of that name occurring along the main line of the Canadian Pacific railway. The Niskonlith series was tentatively referred by Dawson to the Lower Cambrian. > A new term introduced by R. A. Daly for a block of bedded rocka all dipping in the same direction. A "homocline" may be a monocline, an isocline, a tilted fault-block, or one limb ol an anticline or syncline. The field data, however, are insufficient to show which of these categories is represented, G«ol. Surv.. Can., Mem. 68, 1915, p. S3. 27 As a result of recent geological work along the International Boundary line, this group of formations has been provisionally referred by R. A. Daly to the Carboniferous. This correlation is based on the lithological similarity between the crystalline limestone member and a similar formation bearing fossils of Car- boniferous age found by McConnell' and DalyMn Rossland district. Dalv also notes the similarity between Lindgron's' Wood River series of supposedly Carboniferous age and the Pend-d'OreiUe group. He also calls attention to the lithological similarity between the Slocan series and the Pend-d'Oreille group. The rocks of the Slocan series were first referred by McCorneil and Brock* to the upper or middle Pala-ozoic but Schofield' obtained evidence during the field seast)n of 1914 leading him to refer the whole sedimentary series to the Beltian or Fre-Cambrian. From the above statement it is evident that much uncer- tainty ex-.ts as to the age of the Pend-d'Oreille group and that additional stratigraphic work is required before it can be deter- mined.* MESOZOIC. TRIASSIC ( ?) Hall Series. During the field work of 1914 a series of sedimentary for- mations was found within the volcanics of the so-called Ross- land group. The series is well exposed in the valley of Hall creek and has been mapped as a separate unit under the name Hall series. ■ McCom.ell. R. G., Explanatory notes to Trail 8h«t, G«)l. Sur.. Can . |1?'- • Daly, R. A., "Geology cf North American Cordillera at 49th Parallel. Mem. J8. pt. '■ "■. Lin'dgren. W., 20th Ann. Report. U.S. Geol. Surv.. part III, pp. 86-90. 1900. • Eiplanatory notes to We«t Kootenay map sheet; Geol. Surv., Can. » Schofield. S. J.. Geol. Surv., Can., Sum. Rept. 1914, p. 38. . iLce writing thi, and duxin, the 19.6 field «a»n fo«i., «- '-"^.'-^f ^^^t NWtonlith •erie., which at leart provet the Poet-Cambnan age of the rocks: (Geol. Surv.. Can.. Sam. Rept 1916. in preparation). 28 Distribution. The Hall series extends in a general north- •outh direction from the east side of Toad mountain and Neman creek in Nelson area southward to the May Blossom property, where it becomes narrower and is cut off by a monzon.te chono- '^ ' The widest exposure of the series is in the vicinity of Barrett creek, and, as indicated on the map pinches both northward and southward. The maximum thickness of the series is aboul 7,000 feet. _. , . -.^^ Lithology. The Hall series is composed of coarse to tin conglomerates (chiefly arkosic), sandstones, and argillites, al considerably mashed and altered (Plate IV). The conglomerat. is heterogeneous in character containing pebbles of the olde rocks which range in size from a fraction of an inch to one foo and more in diameter. The pebbles include quartzites. green stones, argillites, quartz grains, and feldspathic material. Th sandstones are usually red in colour and are made up in larg part of quartz and feldspar. . Structure. The Hall sedimentary series appears to be ir folded with volcanic rocks of contemporaneous age. chiefl augite porphyrites and related pyroclastic types. Since deposii ion, the series has been uptilted by mountain-building for« and n'>w dips steeply to the west or has a vertical attitude. Origin. Age, and Correlation. The lithological charactt of the sediments of the Hall series leads to the inference that the were in large part laid down subaerially, probably on a dell extending out into an epicontinental sea. During an interv free from volcanic outburst, coarse giavels and sands we washed down from a land surface of moderate relief and becan interbedded with mud and silt. The red colour of the sandston an-* the dark colour of the mudstone or argillite indicate pro abl> semi-arid conditions of deposition with seasonal rainfall. .roel^l^ ffoTthewetical con,, icration. and geological ob^rvation. that thed cS^Uo^ft theTormation of r«l .hale, aad »nd.ton« ..merely ^e alternaUon o^^ of warmth and drynes, with Kason. of flood, by mean, of which hydrauon. b"' "P«* fXlof theTrruginou, material in the fl~f-'''»^,,t^'^" ''J^™^ ttg t^ aupplemenu the decompoiition at the wurce and that which take, place in the long tn So^and great w.« to which the larger river, nbiect U« detritu. roUed along ti 29 The Hall series has been provisionally referred to the Triassic and correlated with Dawson's Nicola series in Kamloopa district. This reference to the Triassic has been made for the following reasons: (1) the distinctly fresher and less altered cond tion of the sediments as compared with those of the Pend- d'Orcille group, and (2) their lithological resemblance to the Nicola series, which conuins fossils of Triassic age grading up nto lower Jurassic' Augite Porphyrite Sills, Flows, and Pyroclastics. A complex group of basic vi Ica.iics, generally included as part of the "Rossland Volcanic group" or "Porphyrite group", encloses the Hall sedimentary series. In Ymir district this group consists of augite porphyrites, augite-feldspar porphyrites, agglomerates, breccias, and their metamorphosed equivalents, greenstone schists of different varieties. Distribution. The porphyrites and their related pyroclastic types have a very wide distribution throughout the region. They underiie virtually half of Ymir map-area. The eastern boundary of the group cuts through the centre of Elise mountain, extending from Clearwater creek southward to the town of Ymir and thence over Pulaskite hill to Salmon river at the southern boundary of the map-area. Westward he torphyrite group extends beyond the map-area, almost to the Kootenay river, but is cut out for several miles along the axis of the Bennington range by the Nelson granite batholith. Lithology. The Rossland volcanics are basic porphyrites chiefly augite porphyrite and an augite-feldspar porphyrite. Both augite andesite flows and fragmental types are present and include amygdaloidal basalts, agglomerates,' tuffs, and breccias bedf. The annual wttUng. drying, and oxidaUoa not only decompoK the original iron minerali but completely remove all trace of caroon. If this conduBon be correct, red ■halea or Mnd.tones, a« distinct from red mud and «nd, may originate under intermit- tenUy rainy, .ubarid, or arid climate, without any close relation to temperature and typi- cally as fluvial and pluvial deposits upon the land, though to a limited extent as fluviaUle sedimenu coming to rest upon the bottom of the shallow sea. The origin of such sediment U most favoured by climates which are hot and alteraitely wet and dry as opposed to cUmates which are either constanUy cool or constantly wet or constanUy dry. > Geol. Surv., Can., Sum. Rept., 1912. pp. 134-135. iVelnleU of epidote cutting the agglomerates are of common occurrence, as weU as gas porei. 30 with their schistose equivalents. The greenstones are in many places epidotized and torsion cracks are common in them. Films of specularite were noted on some fractured sui faces. Fresh types are somewhat rare ami in most cases the rocks are chloritized and calcified to such an extent that microscopic exammation of them is unsatisfactory. Ten micro-slides made from various rock phases of the group were examined and the mam types of rock represented were found to be augite por- phyrite (a coarse and a fine-grained variety), augitc andesite, and basalt with their schistose equivalents. The augite porphyrite is a dark greyish to greenish black rock, studded with numerous dark crystals of augite in a dense groundmass. In many places the coar.se variety passes into a variety without visible phenocrysts. In ca.ses where the dcn.se fine-grained variety is highly silicified it is difficult to distinguish It from certain Pala-ozoic metamorphics. In other places the ^'••Rite porphyrite assumes a brecciatcd or agglomeratic structure; i..-i is, the mass appears to be made up of rounded, oval, and angular fragments, up to several inches in diameter, of a por- phyrite slightly difTerent in colour or texture from the material m which they lie. Torsion cracks are present in the fragments m places. Near the west-n border of the map-area a sill of coarse-grained, augitc-ffld; ; ,n porphyrite outcrops, in which the plagioclase phenocrysts are very much altered. A similar granular type is exposed on the eastern slope of Elise mountain above the Yniir mine, and at a distance resembles outcrops of granite. On the western slope of Elise mountain the augite porphyrite is agglomeratic, vesicular, and amygdaloidal, the gas po'os being filled in most cases with calcite (Plate V). Under the microscope the typical augite porphyrite appears to be com- posed of phenocrysts of augitc, hornblende, and plagioclase feldspar lying in a fine groundmass chiefly of plagioclase and hornblende. The hornblende has a gretn colour, low pleo- chroism, and in the case of some of the larger individuals the core is colourless augite, indicating that much of the hornblende is of secondary origin. The plagioclase is chiefly labradorite. Structure and Origin. The general lithological and structural relations of the augite porphyrite masses to the bedded rocks, I 31 in which there is a parallelism of strike and dip, indicate that the botlies of augite porphyrite probably represent both sills and contemporaneous surface flow i and fragmentals. On the north border of the map-area, west of Salmon river, a series of auijite prirphyrite sills 50 feet thick and upwards outcrop*. They pinch and swell and preserve their porphyritic texture to the actual contact with the shearecl eruptives. The porphyrite includes rounded fraRments of relcanics (characterized by torsion cracks) intervening between the bordering sills and the central area of Hall sedimenatry series, suggests the possibility of close folding with repetition of formations. If this is true the Hall series occupies the axis of a compressed syncline and represents the youngest tion of the group. The lava flows and pyro- clastics antedate the deposition of the sediments; and the sills represent the deeper seated injection of the same magma contem- poraneous with or slightly following the surface eruptions. Further detailed study of the regional structure of the entire area of Rossland Volcanic group is necessary before safe con- clusions can be drawn regarding the structure and nature of th" possible folding in this complex group of volcanics. A^e and Correlation. The augite porphyrites and related volcanics of the Rossland Volcanic group are provisionally I Locally referred to at Uie Summit Ridge volcanic!. 33 placed in the Triaasic and correlated with Dawson's Nicola group.' Daly in his report on the Rcology along the Inter- national Boundary line states "the more massive phases of the Rossland Volcanic group resemble the ^iicola Triassic lavas on South Thompson river "' JURASSIC. Granite Porphyry Tongues. Younger in age than the porphyrUes of the Rossland Volcanic group but older than the Nelson granite are a set of persistent granite-porphyry tongues which are readily separable from the other members of the Rossland group by their lK)ldness of outcrop. The tongues appear to be genetically related to certain of the ore deposits in the region and on that account it was deemed advisable to delimit their extent and as far as possible indicate their position on the map. Distribution. The main occurrences of the granite porphyry tongues follow the western slope of Elise mountain and a belt not so well definctl occurs west of the Hall series in the vicinity of the Kern mine. The tongues are found most typically devel- oped at the Silver King mine on Toad mountain. Lithology. The Rranite porphyry when fresh is a green or greenish-grey rock generally spotted with prominent crystals of orthoclase, up to one inch in length, embedded in a fine-grained groundmass made up chiefly of quartz and feldspar. Apatite and zircon are present as accessory constitutents. Mu of the quartz is secondary and in some thin sections of the rock appears in the form of rosettes. The orthoclase shows incipient scricitiz- ation along the cleavage planes. The edges of the crystals are scricitized first, thus forming secondary border rims. In most cases the granite-porphyry is much altered and schistose. It appears to have been subjected to regional movements that did not afifect the Nelson granite. The sericitized orthoclase crystals exposed at the surface, weather from a light to a dark ' "Geology and ore depotlu of Rowland," Geol. Surv., Can., Mem. 77, 1915, p. 20«. *Gcol. Surv., Can., Mem. IK, p. 372. S3 pefn colour and at a distance the rock might be mi.takcn for augite porphyrite. Other fcrruginou. varieties on exposure weather red and through disintegration the crystal* of orthoclasc are »c'. free. The alteration in some cases has l)cen acwmpanu-d by the introduction of iron and magnesium to form hornblende, and in other cases the rtKks are calcified. The quartz pheno- crysts. where present, are corroded. One specimen of granite porphyry contained microscopic inclusions of schist. The granite porphyry at the Tamarac mine wasfoundto contain inclusions.)! greenstone schist up to 14 inches in length, with longest diameters standing vertical. In this case the greenstone had become schistose before the intrusion of the porphyry. Structurr and Origin. The granite porphyry intruMons have the form of apophyses or tongues of irregular shape with a dominant north-south trend. They generally follow the strike of the greenstone schists into which they are intruded and in many cases the tongues appear to have been metamorphosed along with the femic schists to form light, greenish ^rey sericitc schists The light-coloured schists stand out in strong contrast to the dark greenish schists derived from the femic p«jrphyrite members of the Rossland group. Age and Correlation. The granite porphyry is intrusive into the porphyrite and volcanic members of the Ros.land group, and i. intruded by the younger Nelson granite. The intrusions probably represent the earliest manifestations of the Jurassic revolution in the region. The tongues, although more alkalic in character than the so-called diorite porphyrite {gran.Kliorite porphyry) of Rossland, may represent igneous intrusions of the same age. Nelson B 'tolith, Stocks, and Tongues. All the preceding formations are intruded by large masses of granitoid rocks, which form a part of what is termed the Nelson batholith, and, as may be seen from the map, cover an extensive area in the Ymir district. The term " Nelson granite, though in common usage, is only applicable to very small portions of the batholith. The rocks vary in composition considerably 34 from place to place, the most common type being a granodiorite, a rock transitional between a granite and a diorite.' Distribution. Stocks and tongues from the Nelson batholith outcrop over a large part of the eastern half of the area, occurring as a series of long, parallel intrusions, pinching to a few feet and swelling to a maximum width of 4 miles. The remnants ol rocks belonging to the Pend-d 'Oreille group and Summit series, into which the granitic mass has been intruded and which formed the roof to the batholith, now outcrop as a series of long, parallel bands varying from a few inches to thousands of feet in width. Such down hanging wedges of schist are generally spoken of as roof pendants. The roof pendants which follow the general trend of the schist formations, are injected to such an extent by granitic material from the underlying batholith that it is difficult in places to delimit the various masses by precise boundaries (Plate VI). The contacts are in reality transition injection zones and can be defined only arbitrarily by considering the relative proportions of granite to schist. An isolated mass of Nelson granodiorite outcrops near the northwestern corner of the map-area on Dominion mountain and another smaller area between it and the Salmon river. Lithology. In mineralogical composition the rocks of the Nelson batholith and allied intrusions range from a true granite to a quartz diorite and more femic types. Texturally the granitic rocks vary from a fine-grained granodiorite through several gradations to the coarse porphyritic granite outcropping in the vicinity of the Foghorn and Wilcox mines. The porphyritic granite is a light grey to pinkish grey rock characterized by a very coarse grain and in places by well pronounced augen and gneissic structures. The granite is traversed by well-defined joint planes, the master set being closely spaced and corresponding in str'ke and dip with the older intruded formations (Plate VII B and C). Large phenocrysts of alkalic feldspar (orthoclase and microcline) and, less commonly, of acid plagioclase are embedded in a groundmass of quartz, ' According to W. L4ndgren nanodiorite contMna 8 to 20 per cent alkali feldipart and the •mount of plagioclaK li at least double that of the alkali feldipar. Am. Jour. Sc 4th aer vol. 9, 1900, p. 269. 3S orthoclase. microcline, biotite, and sericite with accessory magnetite, apatite, and titanite. The porphyntic granite resembles in many respects Daly's Rykert granite at the Inter- national Boundary. The most common rock of the Nelson batholith is a grey granodiorite of medium texture, with orthoclase and plaKioclase (chiefly andesine) feldspar, biotite or hornblende, and quartz as essential constituents; microcline, titanite. magnetite, apatite, and zircon as accessory constituents; and chlorite, epidote, kaolin, and limonite as alteration protlucts. The granitic rocks of the stock and tongue members of the Nelson batholith are predominantly fine-grained or porphyritic. They have, however, the same mineralogical composition as the parent granitic batholith and are sometimes referred to as aschistic^ (undifferentiated) dykes. Genetically connected with the Nelson batholith are many diaschistic (differentiated) dykes which, in contrast to the aschistic dykes, represent extreme divergences from the mam parent batholith. They differ from one another in composition, ranging from aplites, the acidic extreme, to lamprophyrcs, the femic extreme. The aplites are light grey or pinkish in colour and are most numerous in the more femic phases of the batholith at or near its contact with the schists. They are of very fine, even grain, in which are seen occasional black specks of biotite. They break with a slightly crumbly fracture and have the sugar-like, granular texture of typical aplites. Lamprophyre dykes, or femic extremes of differentiation from the parent batholith, occur throughout the whole area. The lampro- phyres are probably of two ages: the older set related to the Nelson batholith and the younger more alkalic set to the Coryell batholith* of Tertiary age. They are dark green to black in colour, weathering and disintegrating readily on exposure to a greenish grey to brown sand. The lamprophyres, as a rule, are persistent dykes with steep dips and are found chiefly in the cover rocks of the batholith. The main types are minette, illr8g£CT, W. C: Die EniptigMtelne del KrHtl8i.l««ebietei, vol. I. Die Ge.teine der Grorudit-Tingualt-Serie. 1894. pp. US-153. ••■Geology »d ore depo.it. of Rowland," Geol. Surv.. Can., Mem. 77. pp. 32. 237-240. 36 kersantite, vogesite, and spessartite. The lamprophyre dykes bear important structural relations to some of the ore-bodies as, for instance, in the Porto Rico and Fern mines. Structure. The rocks composing the bathoHth have com- monly yielded to the differential pressures of mountain-building periods by mashing and flowage producing gneissic structures. The foliation in the gneiss generally corresponds in strike and dip to that of the intruded schists; and both were later subjected to the Laramide orogenic revolution at the close of the Mesozoic era. Secondary structure within the batholith is present in the form of joint planes in two or three directions. Vertical planes in two directions nearly at right angles and a horizontal set are the most prominent joint planes. A north and south trend- ing set with steep easterly dips passing into sheeted zones is common toward the eastern border of the map-area. Diagonal jointing is prominent in the central portions of the mass. In many cases shearing has taken place along joint planes. Origin. The nature of the origin of the Nelson batholith is a matter for speculation. Probably a combination of the hypotheses of active intrusion and magmatic stoping would best fit the facts as observed in the field. The manner in which the granitic intrusives conform in most instances to the structure of the overlying formations favours the former, while the presence in a few cases of crosscutting bodies of granite and the presence of angular inclusions near the contacts and freedom from them in the interior point toward the latter, or stoping hypothesis. Age and Correlation. The date of the intrusion of the Nelson batholith and related stocks and tongues has been generally assigned to the late Jurassic or post Jurassic by McConnell, Brock, and Daly. In the Ymir district there is no evidence of its precise age, other than that it is later than the main orogenic movements, which occurred, probably, in Jurassic times, and older than the Tertiary intrusions of alkaiic granitic rocks. Monzonite Chonolith. Distribution. Between Quartz and Boulder creeks southwest of the town of Ymir there outcrops over an area of less than one 37 square mile an irregularly-shaped intrusive mass (chonolith) bounded in some places by flatly dipping contactsand elsewhere by steeply dipping contacts. The Free Silver and May Blossom properties are situated in and at the border of this minor in- trusion. Lithology. The monzonite is a granular to semi-porphyritic rock. It is a greenish grey to black colour with dark pyroxenes scattered through the light-coloured feldspathic constituent.^, the contrast between the two giving the rock a mottled appear- ance. In mineralogical composition the monzonite is of a somewhat syenitic type with femic constituents in large amount. It may be classed as between an augite-biotite syenite and a normal monzoni . -iential constituents are augite, biotite, orthocla; plagioclase; the accessory are iron ore, apatite, horno.(.nUc, and quartz; and the alteration pro- ducts are chlorite, epidote, kaolin, and limonite. Structure and Origin. The monzonite appears fresher than the Nelson granodiorite and does not show the effects of regional dynamic metamorphism as much as does the granodiorite. The exposed contacts between the monzonite and the Rossland Volcanic group are sharp, with little variation in the monzonite but considerable metamorphism in the intruded compact rock. This crosscutting, monzonite mass is very irregular in form and may be classed as a chonolith} Apophyses or tongues of monzonite porphyry apparently connected in depth with the chonolith were noted farther north in the vicinity of Barrett and Hall creeks. The contact relations of the monzonite with the older formations indicate its intrusive nature, and the size and shape of the mass and its homogeneity in texture and mineral com- position indicate in all probability that it solidified under a thick cover of overlying formations. There is no eviilcnce in the Ymir district to indicate that the monzonite magma or ' Daly, R. A.. "Classification of igneous intrusive bodies." Jour. Gcol.. IW.S, vol. XIII, p. 485. Daly defines a chonolith as "an inneous body (a) in;ccted into dislocattd rock of any kind . stratified or not ; (b) of shape and relations irregular in the sense that they are not t hose of a true dyke. vein, sheet, laccolith, bysmalith, or neck; and (c) conii«5ed of maKma either passively squeezed into a subterranean orogenic chamber, or actively forcini! apart the country- rocks. Word derived from .Vui"s. a mould used in the casting of metal, and ' iB'iS a stone." 38 molten rock reached the surface to form latite flows. Age and Correlation. The monzonite is younger than the Hall series, the augite porphyrite and the granite porphyry, and is older than the main period of mineralization and the Salmon River monzonite and pulaskite. It is considered that the monzonite chonolith is intimately connected in origin with the Nelson batholith and closely followed its intrusion, in late Jurassic or post-Jurassic time. The Ymir monzonite may be correlated with similar intrusives at Rossland and elsewhere throughout West Kootenay district. CENOZOIC. TERTIARY. OUttocene(?). Salmon River Monzonite Stock. Distribution. About one mile south of Ymir on the Nelson and Fort Sheppard railway a small stock of coarsely granular monzonite forms prominent spheroidally weathered outcrops. The rock disintegrates rapidly into huge bouldery masses through exfoliation and concentric weathering on joint blocks. Lithology. The Salmon River monzonite is a dark greenish grey, coarsely granular rock with stout prisms of augite and biotite in a feldspathic matrix, the contrast between the twc giving it a mottled appearance that is characteristic. The larger crystals of feldspar schillerize in sky-blue colours whicli are particularly brilliant on wet surfaces. Under the microscope the augite appears as the pale green almost colourless diopside and the crystals commonly measure between one-eighth and one-quarter of an inch or more ir length. The orthoclase is a soda variety and the plagioclas* which is present in relatively small crystals is labradorite Apatite and magnetite are present as accessory constituents and kaolin and chlorite as alteration protlucts. A specimen ol Salmon River monzonite collected by R. A. Daly from a similai stock farther down the valley was analysed by M. F. Connor o\ the Mines Branch and found to have the following composition 39 Analyses cf Sahmm River MotuonUe. SiOi TiOi AkOi FeiOi FeO MnO MgO C«0 SrO BaO NaK) KiO HiOat 110"C HK) above UO" C P.O. 50.66 1-32 16-91 1-71 617 0-16 5-50 8-26 008 0-23 2 4 1 89 45 14 06 91 11 100-45 52-38 1-10 15-29 2-99 5-53 0-10 5-84 7-30 0-15 3 3 III 25 68 84 21 63 75 100-04 62-59 0-54 17-23 1-51 I-Q2 tr. 1-30 1-99 550 6-74 0-30 6-ii 99-83 I. Salmon RWer monzonite, M. F.Connor, analyrt. p„__ II. Basic contact phase (monzonite) Coryell batholith, M. F. Umnor, III. Coryell puUskite, north of Record mountain, ProfeMOC DIttrich, analyst. Structure and Origin. The Salmon River monzonite is traversed by two or three sets of 5'-' t planes rather widely spaced, a flatly-dipping set being m. mment, as illustrated in Plate X. The manner in which tk itrusion assumes a rounded to oval outline, in places crosscv .I..g the rocks of the Pend-d'Oreille group, apparently independent of structure, is highly suggestive of the possibility of the pipe-like mass rep- resenting the eroded core of an old volcanic conduit. The occur- rence of pulaskite in the central porUon of the stock further favours this possibility. Age and Correlation. The Salmon River monzonite stocks have been referred by Daly' to the post-Eocene (Miocene?) and may be correlated with the border phases^ and cupola stocks and tongues of the Coryell batholith at Rossland.* ■ Daly, R. A. Geol. Surv., Can., Mem. 38. pt. 11, p. 317. • Compwe analysi. of baric border pluue ol Cory..l pulaAite with Salmon Rl«r mon- """••Geclofy and ore deporiu ot Roadand, B.C." Geol. Surv.. Can., Mem. 77. WIS. pp. 29-30,233-23«. 40 At Rossland the writer provisionally referred the porphyridc monzonite intrusions to the tin:e of crustai movements in the Oliogocene and considered them genetically related to the alkalic syenite intrusions (pulasldte). PulaskUe. The core of the Salmon River monzonite stock one mile south of the town of Ymir, is composed of a typical granular pulaskite^ almost identical with that of the Coryell batho- lith farther west. The transition from the one to the other is sharp and may be seen, well defined, near the railway track. The pulasldte is a fresh, coarsely granular rock of a mauve grey colour; it is finely speckled with light to dark green augite and has a typical syenitic habit. It is composed essentially of long rectangular feldspars (intergrowths of orthoclase and albite) with augite (diopside) and biotite. Apatite and titanite are accessory constituents. The large feldspars which have a trachytoid structure display when wet, a brilliant blue schil- lerization colour. The pulasldte is very closely related to the Salmon River monzonite and in all probability represents a slightly later intrusion. Very likely the molten pulasldte reached the surface to form trachyte flows, but erosion has left no remnants of such lavas within the Ymir map-area. Miocene (?). Syenite Porphyry, Granite Porphyry, and Younger Lamprophyre Dykes. Throughout the district there are many salic and femic dykes which are found cutting all the previous formations, with the possible exception of the Salmon River monzonite and pulas- ldte. They are probably genetically connected with a Tertiary batholithic invasion (Coryell) and are predominantly alkalic in composition. All such dykes in this district are later than the main period of mineralization and are of little economic impoitance. ' Pulatkite i* a type of alkalic syenite between > normal syenite and a nepheline syenite witli biotite as chief ferromagnesian constituent. NordmarUte is a quarts-bearing pulaildte. 41 yntic n the Ikalic mile nular atho- ler is c. lauve ugite llyof and anite ive a ichil- River later rface te of phyre t emic with ulas- tiary ic in main ince. ■yenlta ttMldte. QUATEUNARY. Boulder Clay or Till. Till is found blanketing many portions of the upland and valley surfaces, becoming more abundant southward. It is mac*" up of compact sandy clay with stones and boulders scattered abundantly and irregularly through it. Locally it coalesces with the outwash gravels lying along the major streams. Glacial erratic boulders are also of common occurrence. Fluvioglacial Alluvium and Stream Deposits. The modified glacial materials predominate in the valley floors and were in large part laid down by heavily burdened streams as outwash valley-trains contemporaneous with and subsequent to the retreat of the valley glaciers. Such deposits are well stratified and consist of cross-bedded sands, silts, and gravels. The gravels consist of well-rounded pebbles, cobbles, and boulders with lenses of coarse sand. The boulders are mainly of granite although all the more resistant rocks out- cropping in the district are represented. The "older granite porphyry intrusives, Salmon River monzonite, and pulaskite readily disintegrate into a coarse felds- pathic subsoil. The valley slopes and cliff bottoms are more or less skirted by wash and talus accumulations. GEOLOGICAL HISTORY. The Ymir district lies along the boundary line between the two great geosynclinal zones or prisms into which the North American Cordillera may be naturally divided. These are the eastern or Rocky Mountain geosynclinal and the western or Pacific geosynclinal. It has been pointed out by Daly that prior to the Mesozoic the two geosynclinals, as regards their relative periods of deposition and erosion, bore rt 'procal rela- tions to each other. A relatively small eastern portion of the Ymir map-area composed of the Summit series belongs to the Rocky Mountain geosynclinal, whereas the remainder of the area is part of the Pacific geosynclinal. 42 The earliest record in the Ymir district is one of early Cambrian or Pre-Cambrian sedimentation when sands, silts, and clays were deposited in a relatively shallow sea, later to be metamorphosed into the quartzitcs, metargillites, and schists of the Summit series. The climate at the time was probably arid with seasonal rainfall. Sedimentation was followed by uplift and crustal movements. The Palaeozoic era was a time of everchanging epicontinental seas with intervening land barriers of a general low topographic relief. It was during one of the many such transgressions of the Palaeozoic sea that the sand, mud, and lime rocks of the Pend-d'Oreille group were laid down. This long period of relative quiet was terminated by a scries of great disturbances when the region was uplifted above the sea and the rocks deformed and in large part rendered schistose. The Palaeozoic era closed with the beginning of continental conditions of erosion and sedimentation which have continued down to the present time. The Mesozoic and later history is characterized by a higher relief of the region with a stronger tendency towards emergencies rather than submergencies as was so typical of Palaeozoic history. The Triassic opened with vigorous erosion of the newly uplifted land surface. The main event at this time, however, in the Ymir district, was extensive volcanic activity in which coarse fragmental material and lava flows were erupted with contem- poraneous intrusions of porphyrite sills. A short interval of quiet prevailed, however, long enough for several thousand feet of conglomerate, reddish sandstone, and carbonaceous shale to accumulate and these now form the Hall series. In the Jurassic a most important geological event, from the economic standp)oint, known as the Jurassic mountain-making revolution, took place throughout the Cordilleran region. It gave birth to many of the western mountain ranges and was accompanied by much igneous activity and related minerali- zation. Granite porphyry tongues were injected upward into the cover rocks, under great pressure from an invading granitic mass known as the Nelson batholith. Granodiorite and related rocks were intruded in great amount and produced wi'e contact aureoles of various kinds of schist — andalusite and bioiite schists being perhaps the most common types. 43 A slightly younger intrusion of small areal extent, but one closely related to i.ie Nelson granocliorite, took the form of an irregular monzonite mass (chonolith) which forms the country rock of the Free Silver and May Blossom veins. Following batholithic antl chont)lithic intrusion and con- solidation there was a perirxl f)f extensive fissuring and mineraliz- ation and during that time the main ore dep "Gwlogy )f Fnmklin mining camp," G«ol. Surv.. Can., Mem. 56. p. 6S. 44 During the Pleistocene refrigeration of climate, the Cordil- Icran ice-sheet advanced and retreated leaving much drift. At least two distinct periods of valley glaciation and alluviation succeeded the disappearance of the ice-cap. With the retreat of valley ice the eroding activity of the streams increased and the dissection of the alluvial gravels, sands, and silts began. A scries of terrace steps mark successive stages in this down-cut- ting process. At present stream deposits are being laid dowr at certain aggrading sections in the valley Lottoms while th« accumulation of subsoil, soil, and "wash" continues under th« action of frost, ice, snow, rain, and humus. SUMMARV OF GEOLOGICAL HISTORY. The geological and physiographic history o. the Ymii district may be presented for the sake of conciseness in thi following tabular scheme: PalaoMoic. (1) Cambrian or Pre-Cambrian sedimentation in a shallow epicontinenta sea with accumulation of sand, silt, and clay (Summit series). Seasonal varia tion in climate from arid to pluvial conditions. (2) Emergence of district above sea and continued erosion. (3) Transgression or a Post-Cambrian sea over a downwarped peneplair Marine se jr[«.siiG. Althou({h many of thi-se have characteristics in . inn ' , no two dc.x)sit8 are alike li t'l on ai . . ' . ' III/ ■ ti ' the rt'.i of moi ( will not ncces- ' i» ■■ akes have ally established J been disastrously ion of development ther less deserving and geological principles that . pt' sarily apply to another. Oi t' been made; for geological y< \ as applicable to certain mi. in employed in others, resulting u on certain deposits and the wa^^t- occurrences of ore. Owing to recent advances in the study <>f ore deposits and their origin it is now possible to apply gcolog>' to mining with a much higher degree of accurac y and safety than heretofore and it will be possible in the future to carry on prospecting and mine development in a much mon^ scientific and economic manner than ;it present. It is important, therefore, that all the known mineral deposits of the province be systematically examined and classified and the basis for their classification made clear. By so doing investigators will know the criteria by which the various types of deposit may be recognized and referred to their proper place in the scheme. In this case the natural and ideal basis for classification would appear to be the genetic one; for upon the origin of an ore deposit depends the localization of ore shoots, their persistence laterally and in depth, and other fundamental problems most vital to the life of a mine. The Ymir district, although at present a comparatively small producer, presents a number of diverse types of ore deposit, and the need of some such classification was felt in describing and correlating in the succeeding chapter the fifty or more properties scattered throughout the area of the map. In this 47 chapter, then-fore, after dealinR in .i general way with Mu- mode of occurrence, Htructure, anil character «>f the variouc Ymir ores and Kangues, a i«ccti<'n is devotol to their origin and age and their correlation with other better known ore de[xwit(t in the province. Accompanying this section is a table of clax'-ification of British ( olun bia on shoots, Iwised on the physical conditions of their deposition and origin. The table, of necessity, is tent- ative and subject to change and revision a* mine development and geological field work progress. «>RE OCCURHESCE. The ore flcposit? of the Ymir district occur chiefly in quartz veins, the economic importance of which depends <«n their gold, silver, and lead content. The most important veins 8<) far developed are indicated on the geological map (in ixxket). They occur both in the granitic rocks of the Nelson fjatholith and in the metamorphic rocks of the Pend-d'Oreillc and Rossland (groups. No deposits have U-en found in .he Summit serie.*, although the gold-quartz veins of the neighlwurinK Sheep Crtck camp occur in the southern extension of that sene*. TYPES OF ORE DEPOSIT. For convenience antl clearness of treatment the Ymir deposits are descrilxnl in the order ol their present importance under the following heads: (1) Ore-»hoo<» in fissure veins cutting the country rock form,, ions diagonally or at right angles. .... -.u .t, (2) Ore-shoots or pockets in fissure or shear zone veins striking with the country rock formations. (3) Replacement ore shoots in limestone. For an amplification of the following brief general descrip- tion of the ore deposits the reader is referred to the detailed accounts of the various properties in the succeeding chapter. Fissure Vein Ore-Shoots Cutting Formations. To this class belong the most productive and persistent ore-shoots so far developed in Ymir district including, amongst 48 others, the ore-shoots of the Ymir, Yankee Girl, Dundee, Wilcox, and Fern mines. The shoots occur in veins which represent quartz-filled fault fissures having a general northeast by east strike with steep northwesterly dips. The shoots vary in size, shape, and pitch, depending as a rule on local structures. In ■lEj ;^ I Figure 2. Block diagram to show localization of ore-shoot in quartz filled fissure vei.i at intersection of vein with eranite porphyry tongue aoproaching main granite mass. Typical of shoots in the Dundee, Yankee Girl, and other properties south of Wild Horse creek. certain cases the wall rocks of the vein are impregnated with ore and may be mined. Most of the ore-shoots owe their localiz- ation to changes in the country rock formations traversed by the fissure vein or to the intersection of dykes or faults with the veins. This is particularly applicable to fissure veins which 49 intersect the country rock formations at acute angles (Figure 2). Veins of this character occur commonly in the contact injection zones between the rocks of the Pend-d'Oreille group and the Nelson granitic batholith. The faulting along the vein fissures has been such as to tend to offset or "heave" the northern or hanging-walls eastward with respect to the southern or foot-walls. Where the fissure planes were curved and undulating, the faulting along the planes resulted in the formation of pinches and swells in the vein, both along the strike and along the dip of the fissure. The swells in some cases afforded favourable places for ore-shoots. In character and direction the faulting in the Ymir district corresponds to that which took place along the principal vein fissures of the neigh- bouring Sheep Creek gold camp as well as to the regional faulting in the heavily-bedded quartzites of the Summit series at the International Boundary. In the case of the Sheep Creek gold veins, the ore-shoots pitch in the direction of the dip of the quar- rite beds (Summit series) and were influenced by the nature of the faulted walls, whereas in the Ymir veins under discussion, the ore-shoots pitch in the direction of the granitic tongues or toward the batholithic source of the solutions. Well-defined fissure veins in some cases cut for hundreds of feet through the Pend-d'Oreille schists, and contain only barren quartz, except where the favourable granitic intersection is encountered. Certain vein fissures, amongst others the Ymir, Wilcox, and Tamarac, have a general east-west trend and appear to differ in some respects from the northeast by east striking fissures just referred to. So far as known the ore-shoots of the Ymir vein were independent of granite intersections. As the critical workings of the mine were inaccessible in 1914 it was impossible to determine whether or not any local change in wall rock or intersection was responsible for the localization of the main shoot. The Ymir quartz vein is very strong and well defined on the lowest (No. 10) level but the ore-shoot played out at No. 7 level. The position of ground-water levels during pre- vious geological periods may have been the main factor deter- mining the depth of the ore-shoot. The physical character of the rock also and its amenability to replacement may have been so influential factors as well as the nature of the faulting along the curving fissure which produced the lenticular swell in the vein now stoped out (Figure 8, {M^e 103.) Secondary fracturing in the veins has lowered in some cases the zone of oxidation as evinced by the presence of carbonate zones containing limonite, cerussite, calcite, pyromorphite, and other minerals characteristic of that zone. In the case of the Tamarac, east-west, curving fissure vein which dips flatly to the north, the ore-shoots are localized at relatively sharp bends in the fissure which apparently were in a state of tension and thus afforded ready access to ore-bearing solutions (Figure 3). The lateral extensions of the shoots are limited by dr^ structures in the vein, due to torsional stresses set up in the crust. The massive granite-porphyry bordering on both sides the ore-bearing, granite-porphyry schist acted as units, the western mass being thrust northward with respect to the eastern. The thrust subjected the intervening schist formation to a tor- sional strain which resulted in a crevasse-like fissure of elongated S-shape. The direction of the forces involved and the localiza- tion of the ore-shoots as exposed by underground and surface work are indicated in Figure 3. In other cases in Ymir district ore-shoots or pockets are local- ized at the intersections of mineralized fault planes with the fissure veins, particularly where the angles of intersection are acute. In the case of fissure veins traversing the Nelson granite, as for instance in the northeast comer of the map-area, it is significant that a number of the veins correspond in strike and dip with the master joint planes. The hanging-wall is invariably well defined and marked by both selvage and quartz, whereas the foot-wall is as a rule ill-defined, and contains quartz angulars (Figure 4). The quartz veins, furthermore, have a tendency to be curved with their concave side toward the centre and widest portion of the batholith. This may be explained as due either to shrinkage effect toward the border of the batholith or to sub- sidence of the central portion of the batholith during consolid- ation. The latter would result i -. tensional stresses being set up toward the border of the batholith with the formation of fissure arcs having concave surfaces toward the area of subsidence. i^- 51 /-/T '«CQr, . >> • • . . ■ • f . . .,•••••.■: — 'i^.v^.ett jfo/w^'^'^'e ; .rfi;.- •.:••••.:;••■ — .~^ —'^o "e o/* o'ee "_— -~^*'^/»o*e^ «P^/?/iee-^ Figure 4. Complex fissurre vein at Foghorn mine. 52 Fissure Vein Ore-Shoots and Pockets, Striking with Formations. As is shown on the geological map the regional trend of the formations is in a general north-south to north-northeast-south- southwest direction. It is natural, then, when Ymir district was subjected to the severe strains and stresses set up con- sequent upon crustal readjustments following batholithic in- trusion and consolidation, that breaking points were reached and various systems of fissuring formed. The formational contacts and schist formations of the roof pendants in many cases afforded hnes of least resistance to shearing and fracturing and a great many of the veins described in the succeeding chapter were formed in this way. The Pend-d 'Oreille schist of the roof pendants, and the oldest granite porphyry (Ros.sland group) tongues form the main country rocks of such veins. The granite porphyry tongues are in large part schistose and difficult to distinguish from the darker-coloured greenstone or porphyrite schists of the Rossland group. The ore in the veins of this system of shearing and fissuring IS apt to occur in lenses or pockets and so generally lacks con- tinuity, although it may carry high values. The pockets are dependent in most cases upon dyke or fault intersections, and the best ore is recovered from the veins where the wall rocks are granitic rather than sedimentary. In such cases the granitic dykes invariably strike with the schist formation, but dip at steep angles toward the main batholithic mass. As a result deep development on many veins of this type has proved dis- appointing. Owing to continental and mountain glaciation and the absence of protective lava cappings, the zone of o.xidation in this district is very shallow compared with that in regions farther south beyond the border of continental glaciation. It is. how- ever, more in evidence here and still more so at Sheep Creek gold camp than farther north where glaciation was more intense. The ore in veins of the type under discussion is in many cases enriched by surface weathering and oxidation. iniiii 53 Replacement Ore-Shoots in Limestone. The only case of a replacement ore deposit in limestone, within the limits of the map-area, is that of the Hunter V- Double Standard property, situated on the divide between Hidden and Porcupine creeks. The ore is very low grade galena, zinc blende, and pyrite and carries values in silver and lead with a little gold scattered through a carbonate gangue. It occurs as irregularly tabular masses having "commercial" boundaries and dipping flatly into the hill (Plate VII). The country rock is the crystalline limestone of the Pend-d'Oreille group which, unfortunately, in the neighbourhcxxl of the ore, runs too high in silica to be much desired by the smelters as a mineralized Hux. Surface enrichment on the Double Standard claim has resulted in the formation of small arborescent aggregates of native silver along fracture planes in the ore. CHARACTER OF ORES AND GANGUES. Ores. The ores of the Ymir district may be classified as follows on a basis of mineral content: (1) Ores consisting essentially of auriferous galena (both steel ami cube) and iron pyrites (coarse and fine) with some zinc blende, in a gangue of quartz of varying colour and texture. No copper minerals are present in this cLiss. Rarely cerussite and pyromorphite are present in the oxidized ores. These ores occur in the form of shoots in fault fissures which cut the Pend-d Oreille group and Nelson granitic rocks. They are by far the most important ores yet known in the district and carry values in gold, silver, and lea>l. This occurrence of high gold values in galena and zinc blende is unusual and quite characteristic of Ymir ores. (2) Quartz ores carrying free gold, also a little pyrrhotite, chalcopv'rite, pyrite, and rarely tetrahedrite with associated carbonates and oxides. These ores are found associated with intrusive dykes in the Rossland Volcanic group. (3) Galena ores with some pyrite and zinc blende, carrying values chiefly in lead and silver, in a quartz gangue. The country rock is mainly monzonite. (4) Ores of auriferous pyrites in a quartz gangue. These ores are found generally in shoots and pockets in fissures or shear zones, in oart replacement ores, striking with the enclosing schist and injected granitic formations. (5) Low grade sulphide ore of galena, zinc blende, and pyrite, containing chiefly silver values, disseminated along with silica through a lime gangue. The ore where it is oxidized contains minute leaves of native silver as a surface enrichment product. The country rock of this mineralized flux material is the Pend-d'Oreille limestone and marble. 54 Gangues. The chief gangue mineral in practically every case is quartz. Several varieties of quartz are present, most abundant being: (1) A massive, clear, white variety so finely crystalline that no distinct crystals are visible to the naked eye. (2) A fine-grained dense, bluish variety in some places smoky with a vitreous lustre. The massive, white variety is the most common, although the bluish variety Vvas noted very frequently in stringers in the roof pendants of the Pend-d'Oreille schist. The bluish colour may be due U) the presence of finely disseminated sulphides or included microscopic rutile needles. In the fault fissure veins free gold is most commonly found in the dark, smoky, blue quartz in close association with the fine sulphides, the quartz in many cases occurring as glassy blebs throughout the mass of sulphides. The coarser, more brightly coloured sulphides scattered through the white quartz carry lower values in gold and silver. In the northeastern corner of the map-area large crystals of clear quartz occur in vugs in veins cutting the Nelson granite, and display comb structure. Kaolin, chlorite, and calcite occur less commonly as ganguc minerals depending on the nature of the wall rock. i MINERALOGY. In the following descript. .i of the minerals occurring in Ymir district only those found in close relationship to the veins will be included. The mineralogy of the Ymir veins is comparat- ively simple as a characteristic to be expected in veins formetl as they were by ascending circulation at intermediate depths, with shallow zones of oxidation, and virtually lacking secondary en- richment and contact metamorphic zones. The list of minerals, arranged according to chemical comfxjsition, is as follows: Native cloments Gold, silver. Sulphides Pyrite, galena, rinc ble-i it, chalco- p>Tite, pyrrhotite, tetrahedritc, arse- nopyrite, molybdenite. Oxides Quartr, limonite, wad. 55 Photphate Pyromorphite. Carbonates Calcite, cerus»ite, malachite, azurtte. Silicates Tremolite, epidote, biotite, chlorite, serpentine. Native Elements. Gold (Au). Native gold is found in small flakes and finely disseminated specks in many of the Ymir quartz veins. It is most commonly found in the rusty honeycombed quartz of the oxidized zone. A part of the gold in the sulphides is in the free state but it has not been determined in what form the combined gold occurs. Tellurides of gold have been reportctl to occur in the ores from several of the properties and possibly some of the minutely disseminated gold may be in this form. Silver (Ag). Native silver occurs very sparingly as arbores- cent aggregates or flakes along fracture planes in the oxidized ore of the Hunter V-Doubl" Standard property. It is associated with limonite and tarnishc to a greyish black. The galena, zinc blende, and pyritc generally contain silver, a portion of which probably occurs in a relationship similar to that of the gold. Sulphides. Pyrite {FeSt: Iron 46-6, Sulphur 53-4 per cent). The sulphide of iron is the r-iost common of the metallic minerals occurring in the district and is found both in the veins and wall rocks. In the quartz veins it occurs in disseminated form either massive or in cubes and cubo-octahedral crystals and may have originated at different periods of mineralization. Much of the pyrite is gold-bearing, partitidariy that associated with galena and zinc blonde. The coarsely crystalline and massive varieties occurring alone, in most cases, carry low values in gold and silver. Galena {Pb S: Lead 86-6, Sulphur 13 4 per cent). Lead sulphide is probably the most sought after sulphide in the district. Occurring a;- it does in the fault fissure veins which cut the rocks of the Pend-d'Oreille group as well as the Nelson 56 granite, it contains most of the gold and silver values. Both the fine-grained, steely, and the coarse, cubic varieties of galena are present. Sphalerite, Zinc Blende (Zn S: Zinc 67, Sulphur 33 per cent). Zinc blende occurs in close association with the galena and pyrite and in many cases carries high gold and silver values. Chalcopyrite (CuFeSt: Sulphur 35, Copper 345, Iron 30-5 per cent). Copper pyrite or "yellow copper" occurs sparingly as impregnations and veinlets in association with pyrrhotite and pyrite. It is chiefly confined to quartz veins cutting the Rossland group. Pyrrhotite (F«r»5,.- Sulphur about 39, Iron about 61 per cent). Pyrrhotite or magnetic iron pyrite occurs very sparingly in association with chalcopyrite and pyrite, chiefly in the veins of the Rossland group. Tetrahedrite or Grey Copper {Cu {Ag)t Sb{As)t S,). Grey copper was seen in small aggregates at the Gold Cup property on Elisc mountain, where it is associated with chalco- pyrite and malachite in a quartz vein cutting the Rossland group. The occurrence of tetrahedrite scattered sparsely through the quartz on this property probably gave rise to the report that tclluride ore occurred in the vein. Arsenopyrite (FeAsS: Iron 34-3, Sulphur 19-7, Arsenic 40 per cent). Arsenical iron pyrites occurs sparingly in the district, but was observed in only a few of the ores collected. Molybdenite (MoSi: Molybdenum 60, Sulphur 40 per cent). Molybdenite is reported to occur in the Stewart Creek belt and at the Free Silver property, but was not seen. The mineral occurs at the border of a very quartzose variety of Nelson granite on Lost creek 10 miles south of the border of the area' and elsewhere in the Sheep Creek district. Oxides. Quartz (SiOt: Silicon 46-7, Oxygen 53-3 per cent). Quartz forms the principal gangue of the veins and, as described in a ' DnrKltk. C. W.. "Not** on the geology of the MoUy molybdenite mine," Jour. Cnn. Mia. laet.. toL XVIII, 19tS. pp. 247-2U. 57 previous paragraph on gangue minerals, occurs in various colours and textures. Limonite (iFtfii 311,0: Iron 59-8, Oxygen 25-7, Water 14-5 per cent). Hyilroiiji oxide of iron is comnifmly f«>und in the oxidizctl zont if the veins as a product of the decomposition of the sulphides of iron and the rusty rolour of many of the rocks is due to the alteration of disseminated sulphides to limonite. Wad {variable Ht A/wjOt). In many cases the wall rocks and selvages of the quartz veins in the oxidized zone, as ex{X)sed in the surface and underground w .kings, arc covered with a thin coating of a dark-coloured, pi .bably impure oxide of man- ganese. The black oxide is particularly noticeable in an- 1 near the (luartz \eins cutting the Nelson granite, and display^ fern- like coatings on fractured surfaces. Phosphate. Pyromorphite( {PbCI) Pbt (POi)»: Lead Phosphate) . A bright yelluw, encrusted, oxidation product was collected in the honey- combed surface ore at the Old Timer property up the North Fork of Wild Horse creek. This was determined by R. A. A. Johnston, mineralogist of the Geological Survey, to be pyro- morphite. This mineral is very rarely found in Canaila, the only other known occurrence being from the oxidized zone of the Slociety Girl vein in East Kootenay district, B.C.' Carbonates. Calcite (CaCOi: Lime 56-0, Carbon Dioxide 440 per cent). Calcite, or calcareous spar, occurs as the mail ^angue mineral of the replacement ore-shoots in the Pend-d'^reille limestone. It is cither massive granular or coarsely crystalline in form, and near the ore it is usually siliceous. It is also found filling second- ary slip planes, particularly in the shear zones striking with the Pcnd-d'Orcille schists, and was evidently formed at a period later than that of the main ore deposition. ' Schofield. S. J.. •'Gtolouy of Cranbrook map-area", Geol. Surv.. Can., Mem. 76, pp. ito-ni. Bowlei. O.. Am. Jour. Sc., 4Ui ter.. vol. 2». IW). p. 40. MJ Cerussile {Pb CO^ Carbov Dioxide 16 5, Lead Oxidr 83 5 per cent). CVruwife i» ri'iKH-ted an occurring in the upper portion of the Ymir ort-shoot where secondary fracturing has locally lowered the zone of oxidation. > Malachite (CuCO, Cu (OH),: Cupric Oxide 71 9, Carbon Du>xidel9 9. Waters -2 percent). Green copper carbonate i. the common alteration product of the ores containing chal- copyrite. It forms coatings on fracture planes and colours the gouge at the surface. Aturite (2 CuCO, Cu (OH),: Cupric Oxide 69-2, Carbon Dvoxide 25-6, Water 5-2 per cent). Blue carbonate of copper i, less common than the green carbonate and was noted at only one property. Silicates. Tremolite (CaMg, (SiO,),: Silica 577, Magnesia 289, Ltme 13 4 per cent). Tremolite was noted in long fibrous aggregates forming with calcitc the gangue of a specimen of ore from the Hunter V-Double Standard property. Epidote (HCa, (AlFe), 5i.0„). Epidote is a common secondary product of rock alteration and is found in nearly all the rocks of the district. Much of it was formed in the rocks prior to the main mineralization. Chlorite (Silicate of Aluminum with Ferrous Iron and Mat- nestumand Chemically Combined Water). Chlorite is frequently found in and near the veins as an alteration product of the ferromagnesian minerals in the wall rocks and in gouge material. Serpentine (HtMg^i, 0,). Serpentine ss. The most im|XM-tant fisMire^ from the economic standpomt (war genetic relationships i. the Jurassic mountain-making revolution and intrusion o! tho Nelson batholith. The orogenic movements at ihat tune uptilted the iedimentary formations to almt»