GUIDE BOOK No. 8 | 2 IR “ scurmenny, NOURSIIN Gi [bee Victoria and return ~“nadian Pacific en (anadian\orthern eth oe PART II ISSUED BY THE ay ett aa SURVEY TTAWA, CANADA, Hitt GUIDE BOOK No. 8 ‘Transcontinental Excursion Cl Toronto to Victoria and return via Canadian Pacific and Canadian Northern Railways PART II ISSUED BY THE GEOLOGICAL SURVEY ae OTTAWA GOVERNMENT PRINTING BUREAU 1913 105 GUIDE BOOK No. 8. Part II. CONTENTS. PAGE. INTRODUCTION TO THE GEOLOGY OF THE CORDILLERA, byalweoimalld AD ally ares tere storey ea 1OKeT Generalstopooraphiyss) 1:5: s coh ee III ClaciationyoftheiCordillerays....) 9. oe 116 Generaltstrationaphiy..4 9606 ee acres ee ae 117 Golwmmarssection xi, h. cack eat ae 118 SUS wapmterranes 922 gaia y accede tes oe 122 SiuswapiSenes i. vuln ey neg 122 Orthogneisses and intrusive granites.... 126 Be lGiame sy Stemiee yn teh. Bintan en cena a teen 132 Gab rianksy stem. wl. (oc eer es oc ae 138 @rdovicianysystem™= 40) oi cee ae 142 Silamesysterme a res. snd cine eee Neon acuee men PLA DD Gvoniannsy Ste tik ant ris eee 143 Mitssissipplantcysvena. seer ee veel emmsyhyatianesy Stein sae aia ara ee A EZCHMMIAMESV SUI ie neue reer 145 MRiassiersy Stein tec teen ase hati cee cee LAS IRaASSICRSV SECM tants erties te uh Se ena, Ze 145 Gretaceousssy.Steme ye ee ee eee eee 147 EOCENE SVS LCE rs oe trae cg ar) Ia ea rec ee 148 @ligoceneisysteniiac yews Geruee niece | Ise 148 Pleistocene system yar ac ee) je ure 149 Ceneralgstructureses sae. es ee te eee 149 Note on the igmeous! bodies;... 2. 9.0-4.5 45. 154 General history. . De eee ee ats US) Specially noteworthy fexttincs Ae ore 164 Billioonaplic MObe were et icine ae a lesen 165 Rocky Mountains (Bankhead to Golden), lot Olah INIA BHO Gane 4 ob aie oo Neo 167 Stratigirap lyse w tere eee es Ni ace wee anne 167 ColummMatssectione awe, cre. a aeeia cee ghee 167 35069—I13A 106 PAGE Pre-Cambrian .....o.022 2) 1 ee 172 Corral Creek formation= 5). 4-- ee 172 Hector formation... 5.22... 5.05. eee 174 Cambriatt.. 2.022035) Se oe eee 174 Lower Cambrian... 2.5.1). >) eee 174 Painview formation... 440-0 174 Lake Louise tormation..(~ .. |e 175 St: Piran formation(::..-5 4. 2. 175 Mit. Whyte formation.=-.... >.> 40 175 Middle‘ Cambrian’ >. -2)5.5 ee 176 Cathedraltionmations 4.) ee eee 176 Stephen formations)... 4. 2 176 Pldon formation...) 04 e e 178 Upper Cambriany 3 2 Ve a ee 178 Bosworth formation... 12. 4-4 oe 178 Paget formation? ).c22 446-0 ee 178 Sherbrooke formation 4.95). 5- ee 179 Chancellorformationa-:.-. eee 179 Ottertail#formation. 20 eee . GIS Ordoviciany . 2.92.2 an ee ee ee 179 Goodsir formationiy.~) 15-1) eee 179 Graptolite shales!. Wee heey ee 181 Silurian. Feit ay hee eee eee ee 181 Halysites beds.-e2 shee se are ee 181 Devonian ns: 2. 20555 pss ha ee 181 Intermediate limestone.) 2. > 55... oe 181 Sawback formation. 35.15 0-44e eeee 182 Mississippiamt .. : 28... eteee cho ee 182 Lower Banfi limestone: s-).... (20) ae ae 182 Lower. Banff shale: ..220. 42) eee 182 Pennsylvanian 2) 52.4 eee 183 Upper Bantt limestone. 2255-50. 7 - eee 183 Rocky Mountain quartzite.) eee 183 Permian 2.60... oe ee 183 Upper Bantt shales] 2) eee 183 Jurassic. nif ee eee 184 Ferme shale. ..5. sl nehoe. eee 184 Cretaceous... eee eee 185 Lower Ribboned sandstones)... ee 185 Kootenay Coal Measuress-] 535) eee 185 Upper Ribboned sandstones) ae sse nee 185 Post-Cretaceous..s.. ¢.5. (4:52) eee 185 Igneous complex. 7.45) 4.2 eee 185 107 my lecistocene andunecentar, wt. s soo ee Annotated guide, Bankhead to Golden........ | Bite Koren zi o) oaycgetuetio’s acute ote ceatea Comer inne, ae me aac? ANNOTATED GUIDE, Golden to Savona, lylecimall dip Atm allyeyeiswte.ce- eet ee WESTERN PART OF THE BELT OF INTERIOR PLATEAUS, Savona to Lytton, bya CharlesoW es Din sdalemeys tie cee issentialeceologwyatss hme ceric oe [rater GUC HOM wat chime tet moe nee ee Maras pli SIO ora) ly." tay eA bent arta ce eine ins ea ON eee: (CIRCE GC ha NR ee et Cece, MURR wean cree a Stracionra playa oe aces te ns Nn mele SUMUMTAIAY INISBOIAs eke digo Sula Be ole abo ge cae ENTE ONEAN ECG lea BIG SeiGe tes BAR Gok Os ead ees On Bart oe Coast RANGE, Lytton to Vancouver, byrGharlese@amiselllin 7 sat nue eee re me OCMU CHOI gyay.2, weiss eos ce an ee eee eae a Columnar sections (by Norman L. Bowen).... Canvonyorehraser river oa, en es eee gli sical feacuness. ws ccceien. aee eee CeOlOe esis eee ee eae Ir ae Orginlandihistorycotathercanyon 4 4a INCLERE MCE Sipe ie teres ad ever nal ernest Mle ing Annotated guide, Lytton to Agassiz........... ase i deltake eam chee elie aA coe Maan PROMOS TAD see ah nt heey Nes old eat GeOlO Ras ee Heel metals ar tae! tees, Male INGKERENCOGME eee rn ae NNeL enee gate 108 ILLUSTRATIONS TO PART II. Maps. Sketch map showing major subdivisions in the southern part of the Canadian Cordillerasn-).03e. a ee eacgan-Hiel dose 40 se. dibesacn iets eee eo ree eee ee (in pocket) Route map between Banff and Golden....................... Route map between Golden and Revelstoke.................. Prairie Hills and Dogtooth Mountains...................... GLC 1a tyres Shae he ase CIE Re (in pocket) Albert: canyons. 5.6 cies ecun scien santa eis oat as ee See Map showing approximate distribution of the Shuswap terrane rocks in south central British Columbia.................. Route map between Revelstoke and Ducks.................... Route map between Ducks and Lytton....................... Route map between Lytton and Agassiz..................00. Route map between Agassiz and Vancouver.................. DRAWINGS AND SECTIONS. Diagram showing metasedimentary schists, thin limestone interbeds, and intrusive sills of the Shuswap terrane; typical relations; locality near Carlin siding .................... Cliff section of aplitic dykes cutting paragneiss (?); Shuswap terrane at Clanwalliames-A anne a eee Diagram drawn to scale, showing development of columnar jointing in Tertiary basaltic flow near Ducks station...... Section illustrating great crumpling of Glacial silts by advancing ice sheet which deposited typical till-on the silts. Locality 3-5 km. west of Cherry Creek station................... PHOTOGRAPHS. Looking south-east from Six Mile Creek along the Purcell trench (Beaver, river valleys) -s0a0e ane ee Looking south from Terminal Peak along the edge of the great escarpment bounding the Purcell trench on the west........ Bastion mountain from the west, showing the Sicamous lime- stone (in the high bluff) overlain by the Bastion schists (background, on the left). The large out crop near the middle of the view is intrusive syenite.................... PAGE. 112 189 189 203 205 215 219 221 245 265 274 126 130 163 234 114 115 125 Aplitic and pegmatitic sills cutting rusty metasedimentary schists and limestone interbeds; Shuswap terrane, western shore of Mara -Armiof Shuswap lakest..- 35-50 eree nee Schistose structure of typical orthogneiss in Shuswap terrane, illustrating static metamorphism. The hammer is about 32 cm. in length. Locality, Albert Canyon station...... Strain-slip cleavage in talc schist of the Shuswap series, at Blind bay. The well developed, low-dipping schistosity is due to eaeliey static metamorphism. Camera case about 7 cm. GIT CRs itis; stile ey ecmietiietes Deane oe cee 3 ane pa Ree Ree Top of Cougar mountain, looking southeast; showing Cougar quartzite as typically developed in the Selkirk range.... 127 129 131 135 109 Summit of the Dogtooth range, looking east from a peak near head of Quartz creek. Slopes underlain by the Ross forma- tion as typically developed in the Purcell mountains........ Summit of Mt. Tupper from Tupper Crest, showing characteristic habit of the Sir Donald quartzite. Photograph by Howard IPRA Wavelets crane aia yeraetaia ha wis miata nhac nei hea career BIER ETE Characteristic outcrop of Triassic (Nicola) basalts near Ducks station. The terrace is composed of the white Thompson IRGWersiltSuamre sone eee ae creme aan Cee oe anaes Looking south from Mt. Tupper to Mt. MacDonald and Mt. Sir Donald (background), showing part of the summit syncline of the Selkirks as shown in the Sir Donald quartzite forming the great escarpment. Photograph by Howard Palmer... . Drag folds in the Cougar quartzite near head of Cougar creek, Selkirk range. Cliff shown is about 15 m. in height. .... Looking north over the South Thompson river, from Campbell's s ranch, 9 km. west of Ducks station. The creek bed in the middle of the view is located on the plane of unconformity between Pennsylvanian limestone (left, light-coloured outcrops) and Triassic conglomerate and basalt (right, dark-colourediouterops) tain (ciecmoeieen intern Contact of the Pre-Cambrian shales (Hector) and the Lower Cambrian quartzites. Exposed in Bath creek, west of I Leese val 2 Sie tere oo BE aR a ER ae nt Pog el Seo phere ain Mt. Temple showing complete Lower and Middle Cambrian section, capped by Upper Cambrian and underlain by Pre- Camlbrianeshales: (Coveredibys talus)iny anne ns oo acre Castle Mountain, showing Cathedral limestone in the lower cliffs; Stephen formation in the talus covered slope; and the Eldon formation in the upper cliffs. (All Middle Cambrian) Fossil bed in “‘ Burgess shale’? on Mt. Field, showing character of the shale, method of quarrying for fossils, and tempor- Ainy Carino OF Co. IDs WANCOHEs coccecgosduno5e5 buctoodnocad The Mitre and Death Trap (pass) to the right. The cliffs on the right are of Middle Cambrian limestone in Mt. Lefroy. A typical bergschrund is shown around this portion of the Ee irovaclaciennt esc tered ray rei cise inies cso oes Cte a Cambrian-Ordovician contact in Mt. Goodsir. The grey rock is the Ottertail limestone, overlain by the dark -coloured Coodsirmshalessycey se see ici weiart oe Lace ered b one cesar A typical view of the Upper Banff shale, exposed in Spray valley ebtepels CAT hppa ene Bn ae mtn ene Thc SRN EME AE i OL oR anne meee Ottertail escarpment showing Chancellor formation forming talus covered undulating surface; Ottertail limestone in Mt. Tupper from Rogers pass. Slopes underlain by Sir Donald CUAREZIL Cote cy tee eee cep rs eek wer eines ee RA eae Illecillewaet glacier in August, 1911. Photograph by H. Ries.. Ilecillewaet glacier in August, 1912. Comparison with preceding figure shows recession of the ice-front during the year precedinge = bhotograplllbyablaRiesna sancti en eee Mt. Sir Donald from Eagle mountain; Mt. Uto in foreground. Photography byallowandsPallimenmsnmeeeeeicion cmi teak PAGE. 139 140 146 155 173 175 176 177 IIo Orthogneiss near Albert Canyon; schistosity due to static meta- MOFPhiSM os s:sgeeei sins Sa eS AE ee ee Quartzites, mica schist and paragneisses, showing coincidence of bedding and schistosity; Shuswap series. At Summit lake, Columbia range, in railway section.........:..........0. View in belt of Interior Plateaus, looking westerly down Shuswap lake‘near Blind: bays ....655500 ci een oe eee Silt terraces on South Thompson river, with Pennsylvanian formations (Cache Creek series) in the background. Look- ing north from a point about three miles above Kamloops View showing the character of the topography about Ashcroft. Looking up Thompson valley towards Ashcroft; Spatsum siding in’ the bottom ofthe valleyz: s 5... 5.4. en ba eee Junction of Nicola and Thompson valleys, near Spence’s Bridge Scarped north wall of Thompson canyon near Gladwin........ Looking southwest from Mt. Ferguson, Lillooet district, showing mountains typical of the Coast range.................... Entrance to Fraser canyon above Yale, with Lady Franklin Rock in the middle of the stream................550.0:- Fraser river, looking down from Yale; valley here widened out on greatly sheared granite of the Coast Range batholith.. Constriction of Fraser river at Hell’s Gate near China Bar. The ledges are composed of jointed granodiorite.......... PAGE. 217 III INTRODUCTION TO THE GEOLOGY OF THE CORDILLERA. BY REGINALD A. DALY. GENERAL TOPOGRAPHY. The North American Cordillera, extending from Bering Sea to the intersection with the Antillean mountain system, has a length of 7,000 kilometres (4,350 miles), an average breadth of about 900 kilometres (560 miles), and an area more than two-thirds that of all Canada and nearly two- thirds that of Europe. This gigantic feature of the earth is a tectonic unit, originating in stresses specially exerted from the Pacific basin. The Cordillera as a whole has, therefore, been fitly called the Pacific Mountain system of North America. The members of Excursion C1. will cross the system where it is comparatively narrow; nevertheless, a straight- line measurement of its width is here about 700 kilo- metres (435 miles). Along the somewhat tortuous route of the Canadian Pacific railway, the distance from the eastern foot of the mountains to the city of Victoriais 1,050 kilometres (650 miles). For purposes of geological description and of orientation in the field, it is necessary to review the general subdivision of the Pacific Mountain system at the railway section. Among the conceivable criteria for subdivision, the purely topographic principle used by G. M. Dawson seems to be the only practical one. In the first place we may distinguish a belt characterized by plateau forms and thereby contrasted with the rest of the Cordillera in the Dominion of Canada. This may be called the Belt of Interior Plateaus. It lies on the eastern side of the Coast range, which is of alpine habit. Elsewhere the subdivision of the mountain chain follows the lines of the master valleys. The greatest of the intermont depressions is that extending from Flathead lake in Montana to the Yukon boundary, a distance of 1,600 kilometres (990 miles). Itisa relatively narrow but actually imposing trough, successively drained by head-waters of most of the great rivers of the Pl1a][Ip1oD UeIpeueD oy} jo J1ed UO NOS 9} UI SUOISTAIPns 1ofeur SuIMOYsS Aeul Y}9yS ee 2. NIVId VAVT cian BGA ee. Pree ee SaaS oy 1s L @D ‘ BS Satiw ool 0 001 T\ >> el be < VIGWoOT Z a) ff OQ : Z We o ajB3g¢ 2 hh ats / > ¥ i es = J i a rT | me NVADO | f Gata A = even oe DIATIDVA ae el aa milton Ge -_— ean \ Q grr Vain oO al ™ geen > . sdoopwe yb f oH ini ane ¥ ~ J | i} (aurz Bec yueg® j oe ‘Il OD NoIsunoxg| 510) Canadian part of the chain: namely, the Columbia, Fraser, Peace and Liard—the last two being principal branches of the Mackenzie river. The larger streams flowing in the depression are: the Kootenay; the Columbia; the Canoe river; the Fraser; the Parsnip and Finlay rivers (Peace river system); and the Kachika river of the Liard system. Many of them leave the trough by transverse gorges cut in the adjacent mountains. The rivers enumerated, as well as smaller ones not specially named, are arranged in regular sequence, draining the trough in opposite (N.W. and S.E.) directions. Although continuous throughout its great length, the trough is not a valley in the ordinary sense. It is like a trench dug by soldiers in a hilly country; such a defensive work is not cut to a uniform bottom grade but is man-deep whatever the slope. This master form in the Cordillera may be appro- priately described as a topographic trench. All the mountains in Canada and in Montana lying to the north- eastward of the trench have long been segregated as the Rocky Mountain system, and the bounding trough has been named the Rocky Mountain trench. A second trench, about 350 kilometres (220 miles) in length, opens in the southeastern wall of the first near Beavermouth and runs southward. It is successively drained by Beaver river, Duncan river, and Kootenay river; for 120 kilometres (74 miles) it is occupied by the fiord-like Kootenay lake. This trough rigorously separates the Purcell Mountain range on the east from the Selkirk system on the west and bears the name, Purcell trench. The Purcell range is thus bounded, east and west, by the two trenches; on the south it terminates at the loop of the Kootenay river in Montana and Idaho. Near latitude 52° the Columbia river leaves the Rocky Mountain trench and flows south, in a wide valley 500 kilometres (310 miles) long, to the Columbia lava-field of Washington State. This part of the Columbia valley may for convenience be called the Selkirk valley. Mid- way in itscourse it bears the Arrow lakes, totalling 150 kilometres (92 miles) in length. East of the Selkirk valley and west of the two master trenches is the Selkirk Mountain system which, like the Rocky Mountain and Purcell systems, extends into the United States. The rugged mountains to the west of the Selkirk valley have been grouped under the name, Columbia EXCURSION C I. Looking southeast from Six Mile creek along the Purcell Trench (Beaver River valley). 115 mountain system. On the north this system is bounded by the obliquely truncating Rocky Mountain trench; and on the south by the lava plateau of Washington. Toward the west the Columbia mountains become less alpine and assume a rough-plateau character, so that it is not possible to make a clean-cut line of division from the adjacent Belt of Interior Plateaus. This zone of topographic transition is crossed by the railway in the region of the Looking south from Terminal Peak along the edge of the great escarpment bounding the Purcell Trench on the west. Shuswap lakes. The Fraser valley at and in the vicinity of Lytton forms a convenient and more definite limit to the Belt of Interior Plateaus, on the west. The Coast range extends from the Fraser valley to the structural depression occupied by the Strait of Georgia and Queen Charlotte sound, to the westward of which is the Vancouver range of Vancouver island. On the south the Coast range terminates at the transverse portion of the Fraser valley, which also delimits the Cascade range entering British Columbia from the United States. 116 In the larger view, the Canadian Cordillera may be broadly divided into four provinces: (a) the Rocky Mountain system; (b) the Middle or Interior ranges, including the Purcell, Selkirk, Columbia and Cariboo moun- tains; (c) the Belt of Interior Plateaus; and (d) the Coastal system, including the Coast range, the Cascade range, and the Vancouver-Queen Charlotte range. The first, third, and fourth of these provinces extend, with but minor interruptions, through Yukon Territory and Alaska to Bering Sea. The Middle ranges as a whole are specially broad in southern British Columbia, but narrow rapidly to the northward and, in the United States, have been broadly depressed and covered by the lava floods of Idaho and Washington states. GLACIATION OF THE CORDILLERA. The field habit of the visible glaciated rock-surfaces and the condition of the drift deposits, in these Canadian mountains, strongly suggest that the great glaciers of the Cordillera were essentially contemporaneous with the eastern ice-cap at its Wisconsin stage. No facts yet determined on the mainland of British Columbia or in Alberta have shown clearly that general Pleistocene glaciation was multiple. It is true that, at many points within the Cordillera and along its piedmonts, younger till rests on water-laid silts, sands, or gravels of Pleistocene age; but this relation is that normal to the inevitable oscillation of ice-fronts during a single glacial period and it is still unsafe to postulate a general interglacial epoch for the Cordillera. However, further investigation of its interior portion may demonstrate one or more interglacial periods, even in spite of the fact that, in a topography so strongly accidented, a more recent glaciation must tend to obliterate the traces of an earlier one. When at their maximum, the Pleistocene glaciers of the mainland formed an interior ice-cap flanked by double rows of valley glaciers. The ice-cap was fed by the local sheets respectively draining the western versant of the Rocky Mountain system and the eastern versant of the Coast range. The eastern slope of the Rockies was drained by many large valley glaciers. These often became confluent as piedmont sheets on the plains of 117 Alberta. Similarly, the western slope of the Coast range bore heavy glaciers which formed thick and broad pied- mont sheets filling Puget sound, the Strait of Georgia, and Queen Charlotte sound. Dawson located the main accumulator of the ice-cap in the interior of the Cordillera between latitudes 54° and 59°, and proved the northward flow from that region as far as 63° N., as well as a southward flow over the 49th parallel into Washington State. Locally, the ice-cap sent thick distributary sheets through low cols and valleys crossing the Coast range; of these the Fraser valley is a signal instance. At many points the surface of the en- era ice-cap is known to have risen somewhat above the 7,000-foot (2,134-metre) contour. Its thickness at the Okanagan valley was at least 6,000 feet (1,830 m.); at Revelstoke about 5,500 feet (1,677 m.). Nothwithstanding its massive proportions, the ice- cap performed comparatively little erosion. Area for area, this necessarily sluggish body was incomparably less power- ful in cutting into bed-rock than were the neighbouring valley glaciers. These were usually much swifter because occupying lines of more concentrated flow. The influ- ence of such concentration, caused by mountainous topo- graphy, is extremely clear in the Canadian Cordillera, and the principle leaves no ground for controversy as to the efficiency of glacial erosion. A smaller, independent ice-cap covered Vancouver island, and another, or else a large number of local glaciers occupied the Queen Charlotte islands. GENERAL STRATIGRAPHY. The section along the Canadian Pacific railway offers an almost complete representation of the main rock systems known in the Canadian Cordillera. The variety of the formations is explained partly by the transverse character of the section through a belted mountain chain; partly by the specially extensive uplift and exposure of the oldest rocks in this geological province. Only the Pliocene and the Miocene fail to appear in the list of standard rock systems, which here ranges from the Pre-Cambrian (pre-Bel- tian) to the Pleistocene. In the succeeding table the more important formations, with thicknesses, are named in 118 order. The measurements and estimates are founded on considerable, more recent field-work supplementing the reconnaissance studies of G. M. Dawson. [5, p. 62]. The total of the maximum thicknesses is colossal (135,000 feet (41,150 m.), including 25,000 feet (7,620 m.) of volcanics), but there can be no doubt that it is correct as to the order of magnitude. Notwithstanding all possible errors of mensuration, it seems clear that the Beltian- Paleozoic geosynclinal prism of the Selkirk-Rocky Mountain region had a thickness greater than 50,000 feet (15,240 m.). Dr. J. A. Allan has found more than 40,000 feet (12,192 m.) of conformable sediments in the Rocky mountains. The still older strata of the Selkirks are nearly or quite as thick. TABLE OF CORDILLERAN FORMATIONS. THICKNESS. System. Formation. Feet. Metres. Recent and Pleistocene..... Fluviatile, lacustrine, glacial... 540.2 Suge. oS eae ol ae Unconformity. Oligocene (?)........ Kamloops volcanic group} 3,000-+ 914+ Tranquille beds (largely Cutis) hese ee see I ,000 305 Unconformity. F.Oceme nnn aeiuse cae Coldwater group (con- glomerate, sandstone, etc.) of Interior...... 5,000 152 4ene Puget group of Coast. =.) -> on ces-s eee Rhyolite porphyry at Ashcroft...3.si06 63 sesile + os sore eee Unconformity I19 TABLE OF CORDILLERAN FORMATIONS—Continued. System. Formation. THICKNESS. Feet. Metres. Lower Cretaceous (Comanchean).... Jackass Mountain group and Queen Charlotte Islands group (sand- stones, shales, con- glomerates) of the WESbooouoboscenvcaags Upper Ribboned sand- stone Kootenay Coal Measures % Rocky Mts Lower Ribboned Sand- stone Jurassic Triassic Unconfor Renmianeese) see Pennsylvanian 350609—2A .|Upper Banff shale Upper part of Nicola group (Interior) Lower part of Nicola group (basic volcanics with limestone Boston Bar group of Coast range (Triassic?) mity with Pennyslvanian. 10,000 3,048 = Rocky Mountain quart- zite (thickness, 244m.) Upper Banff limestone (thickness, 701 m.).... Cache Creek group of the Western Belt (quart- zite, limestone, basic VOICANICS) Meee ae 9,500 2,896 120 TABLE OF CORDILLERAN FORMATIONS—Continued. System. Mississippian....... Devonian Silurian Ordovician Upper Cambrian.... Middle Cambrian. . Lower Cambrian.... .|Eldon limestones Formation. Lower Banff shale...... Lower Banff limestone (partly Devonian).... Intermediate limestone. . Sawback limestone (Dev- onian?); (thickness, 1,12 Os) iene wae ee Halysites beds Graptolite shale Goodsir shale Ottertail limestone Chancellor shales Sherbrooke limestones.. . Paget limestones Bosworth limestones... . Stephen limestone-shale Cathedral limestones.... Mt. Whyte sand- stone shale.... St. Piran quart- zite Lake Louise shale Fairview — sand- StON@s cies cee Rocky Mts. THICKNESS. Feet. Metres. 1,200 366 1,500 457 1,800 548 1,850 563 1,700 518 6,040 1,841 1,725 526 4,500 1,372 1,375 419 360 1@ 0) 1,855 565 2,728 831 640 196 1,595 486 121 TABLE OF CORDILLERAN FORMATIONS—Conclu ded. System. Beltianweeere eee re=beltianessen. (Shuswap series) Formation. Sir Donald quart-) Sel- i kirk Ross quartzite, } Mts. upper part... Conformity in Selkirk Mts; local unconformity in Rocky Mts. Ross quartzite (lower IDE cle) lane or ctee eer Behe Nakimu limestone...... Cougar quartzites....... Laurie metargillites..... Illecillewaet quartzite... Moose metargillite...... Vimestone- saaadee oe: Basal quartzite......... Unconformity. Adams Lake greenstones Tshinakin limestone- metargillites ne soe 4: Bastion schists (phyllites, PGS) carseat Seo one Salmon Arm mica schists. Chase quartzite......... Tonkawatla ke gneiss (?).. : Base concealed. Total thickness (minimum) 35069—25A THICKNESS. Feet. Metres. 5,000 1,524 2,750 838 2,500 762 359 107 10,800 3,292 15,000 4,572 T, 500 457 2,150 655 170 52 280 85 10,000 3,048 3,900 1,188 6,500 1,981 3,200 975 1,800 548 3,000 O14 I, 500 457 135,018 41,150 122 The more important volcanic formations are listed in the table. A few subordinate bodies of lavas and pyro- clastics, together with very numerous intrusive masses, will be noted in the sequel. Igneous activity is registered in the pre-Beltian, Beltian, Paleozoic, Mesozoic, and Cenozoic eras. SHUSWAP TERRANE. Detailed work has been only begun on the widely exposed pre-Beltian rocks, which form the crystalline base ment of British Columbia and share the complexity of the “‘Archean’’ in all parts of the world. They consist of a very thick, conformable, bedded group, called the Shuswap series, and a younger group of granitic intrusives. The whole complex may be conveniently named the Shuswap terrane. Shuswap Series—Owing to structural difficulties, to the ruggedness of the mountains, and_ especially to a dense forest cover, it has not yet proved possible to construct a definitive columnar section for the Shuswap series. It is best exposed on the shore-lines of the Shuswap lakes and of Adams lake, during the low-water season of the year. However, one can seldom follow a contact or other structural plane far from the lake shore. Faults, thrust-planes, and folds are unusally difficult to map in this thoroughly metamorphosed mass of sediments and volcanics. Neither the top nor the bottom of the series has been found. The oldest sediments are inter- leaved with, and underlain by, intrusive granites, chiefly developed as sills. The youngest member on Adams lake where it is best exposed, is truncated by the presenc erosion surface. Obscure as the structures generally are, it is quite clear that the Shuswap series is exceedingly thick. A provisional columnar section may be stated, as follows: 123 Tentative Columnar Section of the Shuswap Series. THICKNESS. Top, erosion surface. Feet. Metres. Adams Lake formation; greenstone schists. 10,000 3,048 Tshinakin formation: Limestone (1,500 ft., 457 m.) Phyllitic metargillite (800 ft., 244 m.) Limestone (1,600 ft., 488 m.) AL costecal eRe eek rs i ewe aT OR eo oS Poca 3,900 1,188 Bastion schists, phyllite with green schists SVE TO) Dodae psteee Men oeeuenn Nac? Speer ane a tenie rember ie ere 6,500 1,981 Sicam ous limestones. 26 ee oe 3,200 975 Salmon Arm schists, m‘caceous............ 1,800 547 CGhaserquantziteres suet owas Sos. och ect 3,000 9gI14 fhonkawatlasparaonmeisss, ...s5c seme: 1,500+ 457+ Base concealed 29,900 9,III The Tonkawatla formation is exposed in a series of railway cuts 3 miles (5 km.) west of Revelstoke. It con- sists of a dark-coloured, massive, homogeneous, compara- tively fine-grained gneiss bearing thin interbeds of white crystalline limestone. The latter are seldom over 2 inches (5 cm.) -in thickness but are locally numerous. Their presence suggests that the whole group of rocks here exposed is of sedimentary origin. The gneiss is rich in biotite and plagioclase and is probably best interpreted as originally a calcareous argillite. The paragneiss passes upward into yet more massive, harder biotitic quartzite, which also carries thin intercalations of limestone. Quartzite of identical habit and tentatively ascribed to the same horizon, is exposed on the slope due south of Shuswap station near the village of Chase. Here the thickness is to be measured in hundreds of metres and a special name, Chase quartzite, has been given to the mem- ber. Besides the thin beds of limestone, the quartzite often shows abundant disseminated grains of carbonate, largely calcite. At Shuswap station the massive Chase quartzite is directly overlain by coarse, glittering muscovite-biotite schist, often garnetiferous and seamed with beds of mica- ceous quartzite. As usual in the Shuswap series, the p!anes 124 of bedding and schistosity are coincident. A thickness of some 1,500 feet (457 m.) is locally represented in these schists. They appear to be of the same horizon as a group of schists exposed in still greater strength on Salmon Arm of Shuswap lake; the name Salmon Arm schist may be given to the member. The coarse crystallization of the plainly sedimentary formation is due to the contact meta- morphism of countless granitic sills and laccoliths. On the cliffy slopes at the eastern end of Bastion mountain the coarse schists pass up gradually into phyllite, a less metamorphosed phase. On the slope just mentioned the Salmon Arm schists are conformably overlain by the thick Szcamous limestone, named for its occurrence at Sicamous station. This is a thin-platy, light bluish-gray to dark gray or almost black limestone, generally interrupted by closely spaced sericitic films. The range in colour tints is due to variation in the amount of carbonaceous matter disseminated through the limestone. The rock effervesces with cold dilute acid, but it is somewhat magnesian. The western slope of Bastion mountain is in part under- lain by the Bastion schists conformably overlying the Sicamous limestone These are best exposed on the shore of the lake, north of Canoe point opposite Sicamous. They are chiefly sedimentary phyllites but at the top are green schists, apparently of volcanic orgiin. On Adams lake, schists like the last-mentioned rocks, are conformably overlain by the composite TJshinakin formation, which, in turn, is there conformably overlain by a gigantic series of greenstones and green schists, the Adams Lake formation, enclosing rare interbeds of lime- stone and phyllite. To this youngest recognized member of the Shuswap series Dawson gave the name “‘Adams Lake series’, and he regarded it as of Cambrian date and of volcanic origin. More recent work has referred it to the Pre-Beltian series. Dawson estimated the thickness of these volcanics as 25,000 feet (7,620 m.); the apparent thickness is certainly greater than 10,000 feet (3,048 m.). No complete field section has yet been found in the great Shuswap terrane and several of the horizons have been brought into the described relations through litho- logical similarities in different sections. That principle is of specially hazardous application in a region of complete metamorphism like that now under consideration. The ‘OWUDAS DAISNIAZUT ST MITA 9Y} JO [PpIu oy} eau do194No ade] OY *QJ9] BY} WO ‘punorsyoV) systyos uolseg oy} Aq UTePIBAO (NIC YSIY oy} UT) 9UOJSOUIT] SNOWIeIIS DY} SuIMOYsS ‘}SaM JY} WoIZ UTeJUNOW UONseg ‘ID NoIsunoxq 126 table of formations will therefore surely need emendation. Nevertheless, it will serve to give a picture of the leading stratigraphic inferences so far made and to indicate in a qualitative way the magnitude and variety of the forma- tions composing the Shuswap series. Diagram showing metasedimentary schists, thin limestone interbeds, and intrusive sills (left blank) of the Shuswap terrane, in typical relations; locality near Carlin siding. Orthogneisses and Intrusive Granites.—Without exception each member of the Shuswap series has been intruded by granitic magma of pre-Beltian age. Some of the largest of these intrusive bodies are true cross- cutting batholiths which have developed strong meta- morphic aureoles. However, most of the intrusions, liter- ally innumerable, are not subjacent or bottomless but are to be classed with the ‘injected’ bodies. Sills are specially conspicuous. Some of the injections are thick and apparently of laccolithic form and mechanism; others have roofs and floors, but cross-cut the bedded formations and these may be described as chonoliths. Dykes are ‘oye] demsnys jo wy eieyy JO d10YS Uto}sam ‘oUeIIO} deMsnyS ‘spsqie}yUI aUOJSoUTT] PU SjsTYyOS ATeJUOUTIpeseyoUI AjsNI BUI}INO s|IIs o1eUIZEd pue ody ‘I D NOISUNOX 128 very numerous, in part representing the feeding channels for the other types of injection. The injected bodies are, in part, clearly satellites of underlying batholiths, but it is possible that many of them are due to the migration of hydrous magmas locally generated in the depths of a greatly metamorphosed terrane. The principal petrographic types in these intrusions are: biotite granite (most abundant); hornblende-biotite granite; two-mica granite (rare); pegmatite and aplite (both very abundant); and orthogneisses corresponding to each of these magmatic species. Extended microscopic study shows that there is little mineralogical novelty; the rock types are duplicated in most of the ‘Archean’ tracts on the globe and are usually gneissic in structure. The extraordinary prevalence of sills and other concord- ant injections is explained by the extreme fissility of the Shuswap sediments and greenstones. This feature is due to static metamorphism. As shown in the following section on structure, the dips of the Shuswap terrane are generally low. Though its rocks have passed through several periods of energetic mountain-building, their dips over large areas do not surpass 15° and their average dip is probably no greater than 35°. The metamorphism is essentially as far advanced where the strata lie horizontal as where they are dipping at angles of 60° to 90°. Further, it seems highly probable that the fissility had attained nearly its present perfection before the Beltian system of rocks was deposited in the Shuswap terrane, and thus at an early date in the earth’s history. The conditions for the metamorphism include: deep burial, with consequent development of ‘‘stress’’ in the vertical direction; and an abundant supply of interstitial water, such as that originally trapped in the sediments and vol- canic beds. The completeness of recrystallization, which is much more striking than that visible in similar geosynclinal rocks of Cambrian or later date, implies that at least one other condition was here necessary. Hypothetically we may find it in a specially steep thermal gradient, con- trolling subsurface temperatures in pre-Beltian times. Field evidence thus leads to the suspicion that the earth was then notably hotter than it was later, when most of the known thick masses of sediments were deposited. ‘u01}e34s UOAULD Woq[y ‘Ay]RooT ‘YSU, Ul ‘WO Ze qynoge st lowUIeYy sy ‘wWstydiowejzour 917238 Bul}eIYSN]]I ‘oueI19} CeMsnysS UI ssfeusoyzAO [eodA} JO 9IN}ONAAS VSO}SIYIS 4 ‘ID NoIsunoxg: EXCURSION C I. 0 10 20 Cliff section of aplitic dyke cutting paragneiss(?); Shuswap terrane at Clanwilliam. The dyke shows nearly horizontal schistosity, parallel to that in its country rocks; all have undergone static metamorphism since the intrusion of the dyke. ‘yoru? ‘uo L noe osvo eIOWIeD “WsTYyd1ourejour 91}e48 IeTpIve 07 onp st APIsOysTYyOS BuIddIp-Mo] pedoyarsp [Pa oyL “Arq purfg 3 ‘setes demsnys ey} JO ISHS 9]eI Uy aBvVACIIO AI]S-UIeIIS ‘I D NoOIsunox| 132 Whatever be the explanation, it is clear that the Shuswap series has not been seriously affected by dynamic metamor- phism. The strata and most of the injected granites were completely or almost completely recrystallized while the strata lay nearly flat. In some localities the effects of dynamic metamorphism have been superposed on those due to previous static metamorphism. An example is illustrated on page 131. Similarly, thermal metamorphism produced by sills or batholiths is generally easy to dis- tinguish from the prevailing regional type. Contact action has either coarsened the grain of the invaded formation or has developed hornfelses bearing minerals characteristic of plutonic contacts. The older members of the Shuswap series are, in general, more coarsely crys- talline than the younger, partly because of deeper burial, but more because of the greater abundance of intrusions at the lower horizons. BELTIAN SYSTEM. Unconformably overlying the Shuswap terrane in the Selkirk mountains is a vast thickness of conformable, unfossiliferous sediments, for which as a whole the name, Selkirk series, has been adopted. The lower and greater portion of these beds is of pre-Cambrian age; the uppermost beds, as exposed in the railway section are referred, on stratigraphic evidence, to the Lower Cambrian. The group is clearly the northern continuation of the Belt series of Montana and Idaho. To the Pre-Cambrian portion of each series Walcott has applied the name ‘Beltian’ as a systemic designation and it will be adopted for present use. In the railway section the Beltian is constituted of the following members. : 133 Columnar Section of the Beltian System in the Selkirk Mountains. APPROXIMATE THICKNESS. Feet. Metres. Top, erosion surface. (Ross quartzite (in part).... 2,500 762 GLACIER Division) Nakimu limestone........ 350 107 (Selkirk series of\Cougar formation (quart- Dawson). zite with metargillitic beds)|_ 10,800 3,292 Laurie formation (metar- gillite, often calcareous; ALBERT CANYON with subordinate inter- DIVISION beds of limestone and (Nisconlith series } quartzite; basal bed, gray of Dawson). limestone 15 m. thick)..| 15,000 4,572 Illecillewaet quartzite...... 1,500 457 Moose metargillite........ 2,150 655 Limestone (marble)....... 170 52 Basaliquartzitessa, sen. oe 280 85 Base, unconformity with Shuswap terrane. 32,750 9,982 In the railway section the basal quartzite is a greenish- gray, fine-grained metarkose, a massive to well-bedded, feldspathic rock of quartzitic habit, though strongly charged with films of sericitic mica. The original material was the somewhat washed sand due to the secular decompo- sition of the underlying Shuswap orthognesis. It will be described in greater detail in a following account of the geology about Albert Canyon station. At its top the quartzite is interleaved with the lowest layers of the overlying limestone. This is a thin-bedded to thick-bedded, white to bluish marble, generally weather- ing to a pale buff colour. It is magnesian throughout, though some beds are more purely calcitic than others. The Moose metargillite has been so designated from an older name of Albert creek, which enters the Illecillewaet river at Albert Canyon station. The middle part of this formation has not yet been found in satisfactory exposure 134 but the whole seems to be a fairly homogeneous argillite, now largely recrystallized by static metamorphism—a metargillite. All phases are charged with sericite, devel- oped parallel to the bedding planes, and occasionally one finds thin beds glittering with coarser mica like a normal muscovite schist. The colour is generally gray, of a dark tint due to disseminated particles of carbon. The Jilecillewaet quartzite is hard, gray, massive to fissile, and relatively homogeneous except for thin intercalations of metargillite. Unlike the basal quartzite, it is poor in feldspathic material and evidently represents a more com- pletely washed and assorted sediment. In the monoclinal section between Albert Canyon and Ross Peak stations, the Laurie formation (named after the mining camp at the railway) is of most remarkable thick- ness. Measurement on the actual outcrops gave the fol- lowing succession. APPROXIMATE THICKNESS. Feet. Metres. Base of the Cougar formation. Gray* phyllitic metargillites: 2se.5. soa. 468 4,000 1,219 @ranretZiteey: sco eek AAA cere etme oak eer heer ate 650 198 Black to darkieray-metarcillite:: asa ae 500 152 Alternating beds of phyllite and quartzite..... 750 229 Black to dark gray, carbonaceous, often pyr- itous metargillite, with interbeds of blackish line StOme: DAG Pes. eth cere ee eee ee ere 9,300 2,835 GrayAquantzitern iste tos ieee ake eee aee 400 122 Black to dark gray, strongly carbonaceous met- argillite, with numerous interbeds of blackish lime StOneyy.gt: an ee CoO ea aE ee 3,500 1,067 Massive, light gray limestone................ 50 15 Top of Illecillewaet quartzite. 19,150 5,837 There is no sign of important duplication by strike- faulting, though some thickening is represented in local © crumples. Admitting all possible duplication suggested by the facts now in hand, this formation must be credited with a thickness of more than 15,000 feet (4,572 m.). On ‘aSULI YITY[OS 9Y} ul podojpeaep AT[eoid Ay se 9yIzJIeNb esnoD surmoys ‘I D NOISUNOXG !ysBayyNos Buryoo] ‘urejunou iesno_d jo doy ZyN 35069 136 account of the general uniformity of composition and habit, no satisfactory subdivision of the formation is yet feasible; because of their limited exposure in the railway zone, the quartzitic beds cannot be used for subdivision. The Albert Canyon division of the Selkirk series is thus chiefly of metargillitic composition. The overlying Glacier division, more especially as it crops out on the wes- tern slope of the Selkirk range, is dominantly quartzitic. Its most heterogeneous member is the Cougar formation, named from Cougar mountain, in which it is exposed on a great scale. In the monocline between Caribou creek and the Caves of Cheops (Nakimu), the formation shows the following general succession. Columnar Section of the Cougar Formation. THICKNESS. Feet. Metres. Conformable base of the Nakimu limestone. Gray, thin-bedded to thick-bedded quartzite, weathering rusty; with thin interbeds of phyllite and white quartzite; a few seamlets of crystalline limestone in the uppermost GQUAREZITSS J ocean rprncrtome rie eee ee ae 5,500 1,677 Conspicuous band of white, homogeneous, Massive qUartzitess wee eer ean tee 300 gI Massive, light gray quartzite, interrupted by many bands of gray, quartzitic grit and coarse sandstone and by beds of dark gray, silicious metargillite; about 1,000 feet (305 m.) from the top, a thick band of massive whiteiquartzite®. .. 4.5 se cee ae 3,000 g15 Quartzitic and phyllitic, gray sandstone and fine conglomerate with metargillite. Near the middle of this zone, angular fragments of altered basaltic rock (bombs?) enclosed in an argillaceous (?)base were found........ 900 274 Alteredubasalticslava ae aceecenert Rin eeerer 50 15 Thick-platy to flaggy, sometimes phyllitic, gray GUAT EZILEee5s oust ot eaten reer 1,050 320 Conformable top of Laurie formation. 10,800 3,292 137 East of the divide of the Selkirk range, the Cougar formation is, on the whole, thin-bedded and more argil- laceous (originally) than in the section just detailed. The equivalent strata of the Rocky mountains—the Corral Creek formation and the lower part of the Hector formation —are still more argillaceous, consisting of gray, green, purple, and black metargillites with interbeds of rusty quartzite. (Seep.172). The rocks of this general horizon thus become finer-grained, less purely silicious, and more argillaceous as the section is followed from west to east. A similar variation characterizes the Rocky Mountain Geosynclinal rocks at the 49th Parallel section. The Nakimu limestone is specially notable as being the most useful horizon-marker in the Selkirk and Purcell mountains. It is truly protean in lithological features, but one is seldom at fault in identifying it in the field. The Caves of Cheops (Caves of Nakimu) have been formed by solution and by the mechanical erosion of Cougar creek, as it follows for some distance a _ subterranean course in the formation. At that, mcst westerly, outcrop the formation is a light gray, fine-grained crystalline limestone. The 10ck is comparatively homogeneous, but carries disseminated sericitic mica in many beds. In the outcrops of the eastern Selkirks and of the Purcell mountains, the same gray type of limestone is interbedded with blackish, very carbonaceous limestone and with rusty- weathering, sandy or pebbly, dolomitic limestone. The thickness is quite variable—from as much as perhaps 600 feet (183 m.) at the Caves of Cheops to a few feet near Beavermouth. These differences are in part original; in part they seem to be due to squeezing-out during the uplift of the mountains. The Nakimu limestone is conformably overlain by the thick Ross quartzite named from Ross peak, a mountain opposite Cougar creek at its confluence with the Illecill- ewaet river. The lower part of this formation is of Pre- Cambrian age; the upper part is probably to be assigned to the Lower Cambrian. All these admirably exposed beds are conformable not only with one another but also with the definitely Lower Cambrian Sir Donald quartzite above. In the section between the Caves of Cheops and Rogers Pass station near the summit of the Selkirks, the Ross formation is relatively homogeneous, with composition as here indicated: 35009—35A 138 Columnar Section of the Ross Formation THICKNESS. Feet. | Metres. Conformable base of Sir Donald quartzite. Gray, rarely rusty, thick-bedded, compact quartzite, with interbeds of gray and brown- ish quartzitic sandstone and grit.......... 1,200 366 Pale rusty-brown silicious phyllite or sericitic quartzite, carrying in the middle a 15-metre bedlofegrayquantziten. sate ciae eee ae 350 107 Gray quartzite, thick-platy and homogeneous, weathering gray and rusty; with interbeds of hard quartzitic grit and sandstone...... 3,700 1,127 Conformable top of the Nakimu limestone. 5,250 1,600 In the grand exposures along the northwestern edge of Beaver River valley the Ross formation weathers more uniformly rusty but is still quartzitic; this section shows an approximate thickness of 5,000 feet (1,524 m.). At the summit of the Dogtooth mountains, the formation is more argillaceous, while retaining its deep rusty colour and numerous bands of fine quartz conglomerate or grit so characteristic in the Selkirks. It is correlated with the shaly to sandy beds in the upper part of the Beltian-Hector formation and in the Lower Cambrian Fairview formation —both exposed in the Bow River valley of the Rocky mountains. Here again the geosynclinal rocks in the east are more argillaceous than those contemporaneously deposited in the west. CAMBRIAN SYSTEM. At the summit of the Selkirk range the Ross quartzite passes gradually upwards into the Sir Donald formation. This is a very homogeneous mass of quartzite, much like *SUIeJUNOU [[90INg IY} UT padojaAop Ay[eotd A] sv UOTPVUTIOJ ssOY 9Y} Aq UlepIopuN sadojg *yYVIeI19 zjAeNG Jo peay ieau yead e wWoIJ 4sva Buryoo] ‘aSue1 Y300}30q 9Y} JO yIwWUINS "I D NoIsunoxy 140 the more silicious phase of the Ross but weathering with a gray, rather than a rusty, surface. On fresh frac- tures the Sir Donald quartzite varies in the colour from white through pale gray and greenish-gray to dark gray, rarely rusty. It is characteristically thick-bedded. Like the Ross formation it is often feldspathic and is charged with numerous lenses of quartz-feldspar grit and fine quartz- feldspar conglomerate. Near the base there is a 53—metre band of pale-rusty to gray quartz-sericite schist. Summit of Mt. Tupper from Tupper Crest, showing characteristic habit of the Sir Donald quartzite. Photograph by Howard Palmer. The®'Sir Donald quartzite forms most of the highest summits of the Selkirk mountains and is terminated above by the present erosion surface. It has yielded no fossils but clearly represents the fossiliferous Lake Louise and St. Piran series of the Rocky mountains. The Lower Cambrian Mt. Whyte formation of the Rockies may also be correlated, tentatively, with the upper beds of the Sir Donald quartzite. The general correlation of formations in the Selkirks and Rockies may be stated as follows: I4I fob oc’ ‘I 90z‘1 096‘¢ z61 of9 {gi 009 ze Col £zg GSoLl‘z 611 o6¢ "SOIIOIN *4990,7 ‘SSUNMOIH *Ppajvaduo) aspg “Tess ss "TOM BUIOJ YaIoID [eIIOD ** aed JOMO]) UOT}eUTIOJ 10J9F] \e6z'e *“(qaed aoddn) uoneuri0j soyoop{ 20) "**UOIVUIOJ MOTATIL YY gfg ar ee eae UOI}EUIOJ VSINOT oYe'] GOHUDOOO0 DOD UOT} LUO; uel mks +z‘ I atrod 000 0.60 UOIJVULIOJ aAUM IN “UDIAQUDD appr, ayy fo aspq arqvutsofuo) *SO1]9 JN 008 ‘OI (qaed ul) uoT}eW40; Ie3N0- = @ +oS¢ Ce ee *9u0}SOUTT] NUITeN e zol oo$‘~ ++" (q1ed s9MOT) 931z31eNb ssoy] ° o$Z‘z = ***(31ed saddn) 931z31enb ssoyy +0008 9) 2 35 97> -ourzqsenb preuog us uvliquies, IIMO'T ‘2ID{ANS UOLSOAT *499J "SSHNMOIH J, “SNIVINNOW AMOOU ‘SNIVINNOW SMADITAS 142 With the exception of the Sir Donald and upper-Ross quartzites, Cambrian strata are absent in the railway section west of the Rocky Mountain trench. The enor- mous development of the Cambrian in the Rocky mountains was demonstrated by McConnell and Dawson. More recent studies by Walcott and Allan have led to its detailed subdivision, as here summarized. Columnar Section of the Rocky Mountain Cambrian. | THICKNESS. Formation. Feet. Metres. Ottertail limestones. ....... 1,725 526 Chancellor shales, etc......... 4,500 1,372 Upper Sherbrooke limestones........ . 1,375 419 Cambrian Paget limestones............. 360 110 Bosworth limestones, etc...... 1,855 565 Eldon limestones............ 2,728 831 Middle Stephen limestones, etc....... 640 196 Cambrian Cathedral limestones......... 31595 486 Mt. Whyte shale, etc......... 390 119 Lower St. Piran quartzitic sandstone 2,705 824 Cambrian Lake Louise shale............ 105 32 Fairview sandstone, grit, etc.. 600 183 18,578 5,663 On pages 174ff. will be found Dr. Allan’s summary description of these formations. ORDOVICIAN SYSTEM. Ordovician strata are represented at the railway section only within the limits of the Rocky mountains and the floor of the Rocky Mountain trench. These beds once extended over the site of the Purcell range and over much 143 of the eastern Selkirks but have there been completely denuded. It is highly probale that the western half of the Cordillera was a land surface during the Ordovician. In our section the system is composed of the Goodsir shales and the Graptolite shales. Dr. Allan credits them with respective thicknesses of 6,040 feet (1,841 m.) and 1,700 feet (518 m.). His account of them appears on pages 179-181. SILURIAN SYSTEM. The Silurian rocks of the section seem to have had the same general distribution as the Ordovician shales. To the younger system belong ‘the Halysites beds, a formation named by McConnell and described on page 181 by Dr. Allan, who estimates the thickness of the formation at 1,850 feet (563 m.) DEVONIAN SYSTEM. Sediments of Devonian age in the railway section are also confined to the Rocky mountains. The Intermediate limestone, named by McConnell and described by Dr. Allan on page 181 has a thickness estimated at 1,800 feet (548 m.) or more. In the Sawback range it is conformably underlain by the unfossiliferous Sawback formation, 3,700 feet (1,128 m.) thick. This is certainly post-Cambrian but its exact age cannot now be declared. (See page 182.) MIssISSIPPIAN SYSTEM. The strata fennel mapped as Carboniferous in the Rocky mountains of our section have recently been shown by Shimer to be partly Mississippian and partly Pen- nsylvanian in age.* The former system is represented in the Lower Banff limestone (thickness, 1,500 feet or 457 m.) and the overlying Lower Banff shale (thickness, 1,200 feet or 366 m.), both named in McConnell’s original report. [2, p. 17]. Some details concerning these will be found on page 182. *H. W. Shimer, Summary Report, Geo. Surv. Can. 1910, p. 147. Since this passage was written Dr. Shimer has concluded from palaeontological evidence that at least part of the Lower Banff limestone is Devonian. 144 PENNSYLVANIAN SYSTEM. In the Rocky mountains of our section the Pennsylva- nian system includes the Upper Banff limestone, and the overlying Rocky Mountain quartzite, with estimated or measured thicknesses of 2,300 feet (701 m.) and 800 feet (244 m.) respectively. Dr. Allan’s account of them is given on page 183. Pennsylvanian rocks show yet greater thickness in the western half of the Cordillera, where they represent the the oldest Paleozoic strata known in the railway section. They have been named by Dawson the Cache Creek group, his own description may be quoted in abstract. Writing of the group as a whole he says: “The lower division consists of argillites, generally as slates or schists, cherty quartzites or hornstones, volcanic materials with serpentine and interstratified limestones. The volcanic materials are most abundant in the upper part of this division, largely constituting it. The minimum volume of the strata of this division is about 6,500 feet. The upper division, or Marble Canyon limestones, consists almost entirely of massive limestones, but with occasional intercalations of rocks similar to those characterizing the lower part. Its volume is about 3,000 feet. “The total thickness of the group in this region would therefore be about 9,500 feet, and this is regarded as a minimum. ‘The argillites are generally dark, often black, and the so-called cherty quartzites are probably often silicified argillites. The volcanic members are usually much decomposed diabases or diabase-porphyrites, both effusive and fragmental, and have frequently been rendered more or less. schistose by pressure . . “In the southern part of British Columbia, the Cache Creek group shows some evidences of littoral conditions toward the west slopes of the Gold [Columbia and adjacent] ranges, probably indicating the existence of land areas there.” [5, p. 70]. Travelling westward over the railway, the Cache Creek rocks first appear in a long section east of Kamloops on the South Thompson river. (See page 231). The group originally covered all, or almost all, of the western half of the Cordillera and has been found to have a thickness of at least 6,800 feet (2,073 m.) in the Chilliwack canyon, near Vancouver. [11, Part I, p. 514, and Part II, p. 559]. 145 Dr. N. L. Bowen’s Agassiz series, noted on page 258, is probably part of the same great geosynclinal. PERMIAN SYSTEM. As yet rocks of Permian age are known only in the Rocky Mountain portion of the railway section. There Shimer has shown that the Upper Banff shale is to be so dated. With a thickness of 1,400 feet (427 m.) it lies conformably upon the Rocky Mountin quartzite. Dr. Allan summarizes the character of the formation on page 183. TRIASSIC SYSTEM. No formations referable to the Triassic are known in the railway section across the Rocky, Purcell, Selkirk, and Columbia Mountain ranges. On the other hand, Triassic rocks are extensively developed in the western half of the Cordillera, where they have had a volume comparable to that of the Cache Creek phase of the Pennsylvanian. Dawson proved the lower Mesozoic age of his Nicola group, which still covers large areas in the Belt of Interior Plateaus. The greater part of this group is constituted of basic vol- canic rocks (chiefly basalts and diabases) with thin inter- beds of limestone carrying Triassic fossils. The upper members of the group are referred to the lower Jurassic. Dawson estimated the total thickness at the Thompson river to be 13,500 feet (4,115 m.), of which at least nine- tenths represents volcanic rock. On account of the extraordinary massiveness of the lavas, it has as yet proved impossible to make a trustworthy columnar section for the group. Thick fossiliferous shales of Triassic age have been found in the Cascade range just south of the railway at Harrison Mills, 61 miles (98 km.) from Vancouver. The Boston Bar argillites, occurring between Lytton and Hope, have recently been shown by Dr. Bowen to be of Mesozoic age and may also belong to the Triassic. JURASSIC SYSTEM. Excepting those noted in the Nicola group, no Jurassic fossils have been discovered in our section west of the “sq]Is IBATY uosduOYL o714M ay} JO pasoduroo st ade110} SY], ‘UOTWe}s SYONC Jesu szeseq (JOIN) Issel1L JO dosojnNo oNsHa}OeIeYD "I OD NOISHNOXY 147 Rocky mountains. In that range itself the rock system is represented by the Fernie shale, with a thickness of 1,500 feet (457 m.). Its description is briefly given by Dr. Allan on page 184. CRETACEOUS SYSTEM. Following the orogenic disturbances near the close of the Jurassic, sedimentation in our section became restricted to relatively narrow geosynclines or zones of overlap. A thick mass of Cretaceous strata was deposited in a down- warp along the eastern limit of the Cordilleran area. Other local geosynclinal prisms were developed near the line of the present Pacific coast. The stratigraphy of each of these two sedimentary provinces needs separate treatment. In the eastern Rockies, west of Bankhead, beds lying conformably on the Jurassic Fernie shale and all of Lower Cretaceous age, have been subdivided into three formations: the Lower Ribboned sandstone, the Kootenay Coal measures and the Upper Ribboned sandstone. Their respective thicknesses are approximately: 1,000 feet (305 m.), 2,800 feet (853 m.), and 550 feet (168 m.). On page 185 is to be found Dr. Allan’s description of the formations. The railway section does not give the full thickness of this geosynclinal, to which Dawson has credited a value of more than 11,000 feet (3,353 m.). Six hundred kilometres (370 miles) farther west, Lower Cretaceous rocks again appear in the section. They cover two principal areas: one at Ashcroft, the other following the Fraser valley north and south of Lytton. Both groups of rocks are doubtless remnants of a single geosynclinal, once covering part of the Belt of Interior Plateaus as well as part of the Coast Range region. A still greater remnant has been mapped at the 49th parallel section under the name Pasayten series, of which the Lower Cretaceous members alone have a thickness of about 7,000 metres. The erosion remnants at Ashcroft and Lytton consist of highly indurated sandstones, argillites and conglomerates. “The sandstones are most commonly of greenish-grey colours, passing on one hand into coarse, distinctly green rocks, largely composed of arkose materials derived from the older [Paleozoic and Triassic] greenstones and [late Jurassic] granites; on the other, into fine-grained blackish sandstones, which grade down perceptibly into argillites 148 - of the same colour.” [4, p.151]. Owing to structural complication, no attempt at a detailed section of the Cre- taceous in either of the areas has yet been successful. Dr. Drysdale estimates the minimum thickness of the Ashcroft remnant at 5,000 feet (1,524 m.), while Dawson indicated a value of 7,000 feet to 10,000+feet (2,133 to 3,048-+m.) for the Fraser valley Cretaceous. A partial section in the latter area (Jackass Mountain series) is given by Dr. Bowen on page 258. Mr. Camsell also refers certain quartz porphyry flows found west of Hope station to the Lower Cretaceous. (See page 273.) EOCENE SYSTEM. In our section rocks of Tertiary age are entirely confined to the western half of the Cordillera. So far as known, they have originated in volcanic action or in fresh-water sedimentation, though it is possible that the Eocene strata of the Pacific coast are partly marine. The formations assigned to the Eocene are: the sedi- mentary Coldwater group; and the sedimentary Puget group. These are local formations and their mutual relations have not been fully determined. The Coldwater group, named and mapped by Dawson, is probably younger and includes conglomerate, sandstone, shale and coal accumulated in the valleys formed during and after post-Cretaceous mountain-building. Penhal- low’s recent study of the fossil floras contained in these beds as mapped by Dawson refers at least part of them to the Eocene proper [6, p. 106]. Dawson estimated the local maximum thickness of the Coldwater beds to be about 5,000 feet (1,524 m.) Like the other Eocene groups, the Puget beds—sand- stones, conglomerates and shales with thin coal beds—are in unconformable relation to the Cretaceous. They attain very great thickness in Puget sound. In the railway section the group is truncated by the existing erosion surface; the remnant of the Tertiary sediments on the lower Fraser has an observed thickness of about 3,000 feet (914 m.) OLIGOCENE SYSTEM. The Belt of Interior Plateaus is widely covered with lavas mapped by Dawson as the ‘Upper Volcanic Group’ 149 and referred by him to the Miocene, as then defined for western stratigraphy [5, p. 80]. Dr. Drysdale is still inclined to regard the lavas as of lower Miocene age (see page 243), though recent paleontological and stratigraphical work by Lambe and Penhallow seems to show that these rocks— hereafter called the Kamloops Volcanic group—should be assigned to the Oligocene. The fossils in question, fish remains and plants, have been found in the Tvanquille beds, a series of local, tuffaceous, partly fresh-water sedi- ments intercalated near the base of the Kamloops volcanics. The Tranquille beds are estimated to have a thickness of 1,000 feet (305 m.); the Kamloops lavas, a maximum thickness of at least 3,000 feet (914 m.), with an original average thickness probably greater than 2,000 feet (610 m.) The Kamloops volcanics are the youngest bed-rocks known in the railway section. Up to the present time no Miocene or Pliocene sediments have been found there. Within sight of the railway, at Mission Junction, is the Pleistocene-Recent volcano, Mt. Baker. PLEISTOCENE SYSTEM. The Quaternary formations are briefly noted at various appropriate places in this guide-book. GENERAL SERUGCTURE: The sedimentary rocks of our trans-montane section belong to three geological provinces. The Beltian and Lower Cambrian strata of the Selkirk mountains and _ their equivalents in the Rocky mountains, with the conformable formations of Middle Cambrian to Permian age, together form a single mass of rocks. In the Selkirks there is perfect conformity between the Lower Cambrian and Beltian systems ; in the Rockies their relation. is reported to be that of conformity at some contacts, and that of moderate unconformity at others. (See page 172). There is no thorough-going unconformity in this gigantic series. It is, in fact, best regarded as a single geosyn- clinal prism of the first order. The maximum thickness of strata here represented is, perhaps, greater than that of any other measured group of sediments. With varying 150 strength and complication, including the presence of local unconformities, this prism is already known to extend from Colorado to Western Alaska. Throughout the length of the Cordillera in Canada and Alaska as well as in the United States proper, the Rocky mountains are almost wholly composed of the prism; hence this gigantic unit has been named the Rocky Mountain Geosynclinal. On its back have been deposited, unconformably, local geosyn- clinals of late-Mesozoic and of early Tertiary dates. These have major axes parallel to that of the older, greater prism and parallel to the general axis of the Cordillera. The whole, compound assemblage of sediments forms the Eastern Geosynclinal Belt of the Cordillera. On the other hand, the chief sedimentary rocks of the Coastal system of mountains—including the Coast range of Alaska and British Columbia, the Vancouver range, the Olympic mountains, the Cascade range, and the Sierra Nevada of California—are of Carboniferous (Pennsyl- vanian), Triassic, and Jurassic age. These beds were deposited in a broad, very long zone of subsidence. The sedimentation was not continuous; there are local uncon- formities in the series. Yet, as a whole, this deposition was long-continued and on a regional scale within the geographical zone described. Since, moreover, the clastic strata were deposited in Pacific water and represent detritus largely from the Eastern Belt, the whole complex q prism may be called the Main Pacific Geosynclinal. After a late-Jurassic orogenic revolution affecting this entire prism, local areas of the now deformed zone were down- warped and received heavy loads of sediment in the form of Cretaceous and early Tertiary geosynclinal prisms. These, along with the much greater Main Pacific Geosyn- clinal, form the Western Geosynclinal Belt of the Cordillera. Between the two belts, on the line of the Canadian Pacific Railway, lies the Shuswap Terrane, the third and last of the major sedimentary provinces. Its rocks are of Pre-Cambrian (pre-Beltian) age. In our section, the eastern limit of the terrane is at Albert Canyon on the western slope of the Selkirks; its western limit is a few miles below the outlet of Little Shuswap lake, in the Belt of Interior Plateaus. Along the railway, the Rocky mountains form a syncli- norium, broken by numerous faults and by occasional zones of mashing. The eastern limb of the synclinorium I5I is thrust at least 11 kilometres (7 miles) over somewhat deformed Cretaceous strata. The western limb terminates in a master-fault running in the general line of the Rocky Mountain trench. This fault, with downthrow of at least 5 kilometres (3 miles), is likewise the eastern limit of a second synclinorium forming the Purcell mountains and the eastern part of the Selkirks. The western limit of this Looking south from Mt. Tupper to Mt. MacDonald and Mt. Sir Donald (background), showing part of the summit syncline of the Selkirks as shown in the Sir Donald quartzite forming the great escarpment. Photograph by Howard Palmer. broad flexure is a relatively simple monocline extending from the summit of the Selkirks to the primary uncon- formity at Albert Canyon. Each synclinorium is unsymmetric, with older strata exposed on the western edge than on the eastern. This is particularly striking in the Selkirks, where the Shuswap terrane is exposed on the west, below the basal beds of the Beltian system, while the Cambrian quartzites appear at the surface not far west of the fault in the Rocky Mountain trench. The maximum amount of uplift registered in the railway section has charactertized the eastern part of the 35069—4A EXcurRSION C 1. Drag folds in the Cougar quartzite near head of Cougar creek, Selkirk range. Cliff shown is about 15 m. in height. 153 Shuswap terrane, where the younger sediments of pre- Beltian age have been eroded away. While the Shuswap sediments attained the thickness of a first-class geosynclinal, no clear hint has been forthcoming as to the geographical source of their clastic material, nor as to the direction of the major axis of this prism. There is nothing to show that the subsiding trough had the Cordilleran elongation which has been so characteristic of the post-Shuswap geosynclines. In two leading respects the pre-Beltian terrane contrasts structurally with the younger geosynclinals. The Shuswap series is less deformed than any of the overlying series, up to and including the Triassic. In the Selkirks and Interior Plateaus the average dip calculated for the beds of the oldest terrane is no greater than 35°, while the averages for large, typical areas of the Albert Canyon division and Glacier division of the Selkirk series, for the Carboniferous, and for the Nicola series, are, respectively, about 38°, 59°, 73°, and 64°. This is true, though the Shuswap terrane obviously underlay these younger formations when they were passing through several orogenic revolutions. Today, the Shuswap rocks in numerous areas each many square miles in extent are nearly horizontal, while adjacent Carboniferous strata are intensely folded. It appears necessary to believe that the earth-shell which has here transmitted the mountain- building thrust had a depth of only a few kilometres; and that this shell was sheared over its basement of Shuswap rocks. The second noteworthy feature is the general failure of the Shuswap strata to show the Cordilleran trend charac- teristic of all the younger formations. The prevailing strike of the basement rocks is about N. 70° E., and thus nearly at right angles to the general Cordilleran strike in this latitude. Quite locally the older rocks have been gripped in a post-Carboniferous plication and show Cor- dilleran strike; such exceptions do not invalidate the general rule. One is reminded of the prevailing E.—W. to N. 60° E. strikes in the Pre-Cambrian rocks of Lake Superior and eastward thereof, in the Canadian Shield. Is this agreement of structural trends in the two Pre-Cambrian areas fortuitous? As already stated, the detailed structure of the Shuswap terrane offers a host of unsolved problems. In general, 35069—45A 154 the deformation of the bedded rocks seems to have con- sisted in warping and normal-faulting, especially the latter. The extremely abundant sills and other intrusive bodies have suffered nearly as much deformation as the invaded sediments. The Western Geosynclinal Belt is structurally the most complex of the three principal provinces. All of its bedded formations, from the Carboniferous to the Cretaceous inclusive, are more or less intensely folded. The thick Carboniferous group has been specially affected by close- folding and mashing, with resulting turmoil in most of the Carboniferous areas. Rocks of the Beltian to the Mississippian, inclusive, are only locally represented in this province, which except for limited areas was clearly a region of erosion during that long period. In our section the oldest known Paleozoic strata are Carboniferous (Pennsylvanian) in date. These lie unconformably upon the Shuswap terrane. A _ second unconformity is well exposed between the Pennsylvanian limestone and the Triassic near Kamloops. A_ third exists at the base of the Lower Cretaceous; a fourth at the base of the older Tertiary (Eocene?) geosynclinal deposits of the Strait of Georgia and Puget sound. An unconfor- mity is registered at the base of the Oligocene in the Interior Plateaus and it probably corresponds to a defor- mation of post-Eocene date. A sixth unconformity is, of course, seen at the contact of the Pleistocene deposits with older formations. NOTE ON THE IGNEOUS BODIES: The sedimentary rocks of the Eastern Belt are, in our section, very seldom interrupted by igneous masses. The remarkable Ice River intrusion (see page 185) and the contemporaneous lavas in the Cougar formation (see page 136) are the only important eruptions observed in the railway zone between the Great Plains and the heart of the Selkirk range. On the other hand, the Western Belt shows not only a much larger number of unconformities, but also an incomparably greater amount of igneous acti- vity. Following the rule illustrated throughout the world, the downwarping of the western geosynclines has been : = s Suod OISSeII (sdo199no painojod-yxAep ‘WYsI1) yeseq pue 97e19WIO] pec e a j 3 UO pdzeOT ST MaTA 2 (SdO19jINO PaIMO]OI-7YSI] ‘IJoeT) VUOJSoOUTIT UeTURATASUUVG Us9M aq AyyUOJUOIUNTJO Id ay ay} Jo eae ul a elses a eee syonqd jo }soM ‘Wy 6 ‘you sjJeqdmed) wor; ‘IaATI UOsdWIOY LL, YINOS Vy} J8AO YOU BuUIyOOT ‘ID NOISuNOXy 156 accompanied by some contemporaneous volcanic action. Surface lavas of both central-eruption type and fissure- eruption type are found in the Pennsylvanian, Triassic, Eocene, and Oligocene downwarps of the Western Belt. In our section the volcanics of the Triassic and Tertiary are much thicker than the sediments of their respective dates. The Western Belt is, in fact, a volcanic province of the first order, whether considered as to volume of extra- vasated material, as to persistence of eruptivity in geolo- gical time, or as to area of country still covered by the lavas. The great cone of Mt. Baker, south of the railway at Mission Junction, represents Pleistocene-Recent vulcanism. Batholithic intrusions are very rare in the Eastern Belt and are entirely absent in the railway section. They cut the Paleozoic strata of the Western Belt on a scale unmatched elsewhere in the world except, perhaps, in the Pre-Cambrian terrane of Eastern Canada, Fennoscandia, etc. The com- posite Coast Range batholith of British Columbia and Alas- ka is about 1200 miles (1930 km.) in length, with an average width of nearly 90 miles (144 km.). The railway section crosses it in the stretch between Lytton and Vancouver. It is composed of granodiorite and quartz diorite, with diorite, biotite granite, syenite, and allied types. There is clear evidence of successive intrusion but it is agreed that the general date of irruption for the greater part falls in the period from the latest Jurassic to the early Cretaceous. In our section the late Jurassic is the pre- ferred date. Yet it is probable that this batholith, like those in Washington State and in the Kootenay district of British Columbia, received large increment or else batho- lithic replacement in post-Cretaceous time. In the railway section itself such Tertiary batholiths have not yet been proved and the earlier date is generally accepted for many smaller batholiths east of the Fraser river as well as for the Coast Range body. Some of the little sheared granitic masses cutting the western part of the Shuswap terrane are tentatively referred also to the late Jurassic. These various bodies illustrate again and again the cross- cutting and apparently bottomless relations of true batho- liths. The main contacts and the attitude of roof-pendants are eloquent in favour of the replacement theory of origin and strongly oppose the “‘laccolithic’”’ theory. Evidence on this fundamental matter has been collected by: Clapp 157 in Vancouver Island; by Dawson, Bowen, Camsell, Le Roy, Bancroft and Daly in the Coast range; and by Daly in the Belt of Interior Plateaus. Their conclusions agree with many recent results of study in the Alaskan and United States portions of the Western Belt. GENERAL HISTORY. The earliest event demonstrated in the rocks of our sect- tion is the long-continued erosion of a silicious( granitic or gneissic) land surface older than the Shuswap series. No actual representation of this ancient mass has been dis- covered, but its existence is inferred from the abundant development of clastic, sandy and argillaceous beds of Shuswap age in south-central British Columbia. This deposition continued long, though it was often interrupted by the precipitation of limestone (e.g., Sicamous formation.) Clastic and chemical sediments together formed a geosyn- clinal mass several kilometres in thickness. Within it there is no sign of unconformity. Toward the close of this epoch of sedimentation and before any notable deformation of the geosyncline, basic lavas broke through the earth’s crust and buried the older deposits very deeply (Adams Lake greenstone). The lower members of the series were drastically affected by static metamorphism, whereby sediments and lavas became converted into true crystalline schists—metargill- ites, phyllites, and other mica schists, quartz-sericite schists, calc-schists, chloritic and uralitic schists. Exces- sive fissility essentially parallel to bedding-planes was thus imposed upon the Shuswap series. It was then invaded by granitic magma which sent off-shoots into the easily split schists, in the form of innumerable sills, laccoliths, and dykes, ona scale seldom matched. The plutonic invasion took place by successive stages, so that older intrusions are cut by younger. As so often the case, the youngest magmas were aplitic or pegmatitic in habit. This salic material forms countless small bodies in the Shuswap terrane. Practically all these intrusions, except the youngest aplites and pegmatites, were themselves sub- jected to static metamorphism, converting them into orthogneisses. The resulting schistosity, generally well developed, is sensibly parallel to the stratification planes of the adjacent sediments. 158 These intrusions must have been accompanied by some deformation of the Shuswap series. In any case, the plut- onic invasion was followed by erosion which bit deeply into the new terrane—a process long continued, implying great uplift above baselevel. The uplift was, however, not accomplished as an incident of intense folding. The average dip of the Shuswap rocks is today low. It must have been lower in pre-Beltian time, for the planes of schistosity and sill-contacts of the Shuswap are nearly parallel to the basal beds of the Beltian system at Albert Canyon and have been upturned to angles of 45° to 55° since Beltian time. The pre-Beltian deformation may well have developed a broad geanticline accidented by slightly tilted fault-blocks. Their average strike possibly corres- ponded with the present dominant strike of the terrane, namely, about N. 70° E. The first sediments formed by the erosion of the Shuswap terrane have nowhere been identified. A great mass of it had already been removed before the region about Albert Canyon was depressed below sea and was covered by the lowest exposed bed of the Beltian system. That bed was a little-washed arkose sand, in mineralogical composition differing but little from the shell of secular weathering on the Shuswap orthogneiss beneath. It is probable that this unconformity represents the preliminary erosion of the Shuswap bedded series at this locality. With the geanticlinal uplift of the pre-Beltian terrane, the oldest known structure visibly paralleling the existing Cordilleran axis was developed. The zone roughly repre- sented by the Western Geosynclinal Belt now became a land mass and the zone represented by a large part of the existing Eastern Belt become an elongated basin of deposit- ion (largely, if not wholly, marine in our section). The floor of the basin slowly subsided and upon it the Rocky Mountain Geosynclinal was accumulated. More or less continuously, from the beginning of the Beltian to the close of the Mississippian, this prism increased in thickness; during the Middle Cambrian it was greatly widened by marine transgression far to the eastward, if not to the west- ward, of the initial shore-lines. Detailed study of the | sediments shows that their clastic materials, even as far east as the Front range of the Rockies, were largely de- rived from the land on the west, though a small proportion 159 was washed into the geosyncline fron land masses located in the longitudes of Montana and Wyoming. In Arizona, Colorado, and elsewhere in the United States, the early Cambrian was a time of erosion following local deformation in the Rocky Mountain Geosynclinal area; and in the late Middle Cambrian a re-submergence, contemporaneous with the marine transgression elsewhere, restored conditions of sedimentation in the zone. In British Columbia and Alberta, however, there appears to be perfect conformity throughout the Cambrian. Opinions differ as to the existence of an erosional break at the base of the Lower Cambrian in the Rockies. Walcott has announced the existence of an unconformity in the rocks of the Bow valley but later observations by D1. Allan and by the present writer indicate that the break at this horizon must in any case be local and does not represent a long inter- val of time. As yet it is impossible to locate the line of maximum thickness for the geosynclinal. In the railway section the Beltian and Lower Cambrian strata grow thinner as they are followed eastward into the Rocky mountains, where the Middle and Upper Cambrian strata have their greatest known strength. Next to the clastic material won from the adjacent lands, the most abundant constituent of the Rocky Moun- tain Geosynclinal is carbonate, chiefly limestone with some true dolomite. All of the pre-Ordovician carbonate- rock and most of the younger limestone and dolomite seems to be best explained as chemical precipitates. The total of the maximum thicknesses recorded for the carbon- ate rocks is more than 6,000 metres (20,000 feet). Though contemporaneous vulcanism is recorded in this great prism at various horizons of the 49th Parallel section as well as elsewhere in the United States, it has added very little to the bulk of the geosynclinal at the Canadian Pacific section. So far as now known, the only occur- rences of lava are those found in the Beltian Cougar formation. In the Pennsylvanian (Carboniferous) period the geosyncline was enlarged both eastward and westward on a scale probably surpassing the marine transgression of the Middle Cambrain. Pennsylvanian sediments, chiefly limestone, were laid on the prism and in yet greater thickness limestones, shales, and more silicious beds were 160 now deposited in the Western Belt, which for the most part had so long remained above sea. The exact sources of supply for this fragmental detritus can not be fully determined. It is possible that islands of the Shuswap rocks still remained, and probable that parts of the Rocky Mountain Geosynclinal were upwarped, so as to suffer erosion during the Pennsylvanian. We know more de- finitely that some of the sedimentary matter in these rocks of the Western Belt was derived from the erosion of contemporaneous volcanoes. Great eruptions of basalt and basic andesite were widespread in the Western Belt during this period. The Permian period has left no record of rock formation in the Western Belt but seems to be represented by con- tinued deposition in the Eastern Belt (Upper Banff shale, 1,400 feet; 427 m. thick). West of the Shuswap Lakes region the Pennsylvanian strata were at least locally subjected to moderate defor- mation, followed by erosion. These events anticipated the deposition of the Triassic shales and limestones, among which exceptionally heavy flows and pyroclastic masses of basalt were erupted. This vulcanism was widespread in the Western Belt, from Alaska to California. In British Columbia it took the form of heavy fissure erup- tions with subordinate central eruptions. Few lava formations are as massive as the extensive and very thick basalts of the Nicola group. It is not certain that Jurassic sediments are represented anywhere in the railway section of the Western Belt. Hence the history of the Jurassic period is here obscure. From the analogy of other regions, particularly California, it is concluded that this part of the belt was strongly folded during the closing stage of the Jurassic. In the Eastern Belt the Paleozoic era was closed by a broad upwarping, by which the sea was largely withdrawn from the Rocky Mountain geosyncline. It is probable that at least the western half of this belt in our section has been out of water ever since and that conditions of erosion there prevailed in the early Mesozoic. The upper Jurassic of the eastern foot-hills is conformable with the Cretaceous of the Great Plains and, like the latter, was probably in piedmont relation to the Cordillera Eastern Belt The late Jurassic orogeny, so powerful in the Western Belt, did not seriously deform the Paleozoic 161 strata of the Rocky mountains; upon those the Jurassic and Cretaceous lie with apparent conformity. In the general absence of Mesozoic sediments in the Middle ranges of British Columbia, it is a delicate, still unsolved problem as to how far the western part of the Eastern Belt was mountain-built during the Jurassic. Perhaps the information will be found along the new Grand Trunk Pacific Railway line. The late Jurassic folding in the Western Belt was immediately followed by granitic intrusion on a grand scale, whereby the enormous Coast Range batholith was outlined, if not largely completed. Many smaller batho- liths and stocks were simultaneously intruded into the older rocks of Vancouver island and of the broad tract between the Coast range and the Selkirks. From that time to the present both Eastern and Western belts of the Cordillera have witnessed subaerial erosion. Near the line of the present Pacific shore and also in the eastern foot-hill zone of the Rockies, local geosynclinals of great depth were formed in the Cretaceous. Examples are: the Pasayten geosynclinal, stretching from west- central Washington to and beyond the Fraser valley at North Bend and Lytton; the Queen Charlotte geosyn- clinal, west of the Coast range; and the Crowsnest geosyn- clinal of the Eastern Rockies. Sediments of both Lower and Upper Cretaceous age occur in these local downwarps of Cordilleran trend. With the completion of the thick Cretaceous prisms, the conditions were ripe for renewed mountain-building and the Laramide revolution deformed most of the Canadian Cordillera. As in the more limited Jurassic revolution, the major thrusts were directed from the Pacific side but they were now, for the first time since the pre-Beltian period, of pronounced effect at the extreme eastern limit of the Eastern Cordilleran Belt. All observers agree that the major deformation of the Rocky Mountain Front ranges took place at this time. Opinions differ as to the date of the great overthrust by which those ranges have advanced outwards, over the Great Plains. Willis has postulated a mid-Tertiary date for the Lewis thrust at the International Boundary, but the present writer is inclined to regard it and the similar thrust in Alberta as incidents of the Laramide revolution [6, p. 340; and 11, Part I p. 94]. 162 Thus, at the dawn of the Tertiary the Cordillera was developed with full vigour of mountainous relief. Its volume in British Columbia, measured above sea level, was then probably at its maximum. Its general history is henceforth one of erosion coupled with intermittent vulcanism of great intensity and with diastrophic move- ments which were of great importance but of an order less than the revolutionary. In the absence of a wide- spread sedimentary record in the mountain chain, it is difficult to state Tertiary events in an orderly, quantita- tive way. Long chapters in the Tertiary history can only be written in the future, after modern physiographic methods have been applied in the as yet unmapped portions of British Columbia. In the Canadian Pacific section no marine sediments of Tertiary age have been definitely reported. The Eocene geosynclinal of Puget sound was doubtless continued into the region of the Strait of Georgia and lower Fraser valley; but this irregular prism represents an intermont basin, in which much of the deposition was subaerial or in fresh or brackish water. There resulted one of the thick stratified masses necessarily developed in Eocene basins from the wasting of the new, vigcrous mountain chain. It is prob- able that the Belt of Interior Plateaus saw, in this period, a moderate amount of local volcanic action, paralleling the greater Eocene eruptions of Central Washington and of the Coast region. The eastern Cordilleran Belt carries no rocks of this period, which was apparently occupied throughout by erosive activity. The Oligocene continued this erosion across the entire chain, but was marked in the Western Belt by long-contin- ued emission of basalts, chiefly of the fissure-eruption type. This vulcanism involved much disturbance of drainage system. Local basins were formed and became filled with gravels, sands and muds, bearing fresh-water fossils (Tranquille group). The Western Belt became affected by moderate orogenic movement, whereby the Oligocene lavas and sediments were locally upturned, sometimes to vertical position. This deformation is not yet accurately dated, but may prove to be of late Oligocene date. Though the local upturning was so pronounced, the Tertiary lavas of British Columbia were, in general, little disturbed from their original, flat attitudes, and it is reasonable to suppose that similarly 163 large surfaces underlain by non-volcanic rocks were not greatly deformed. The Miocene was a time of general erosion across the entire Cordillera at our section. The Cordilleran topography at the beginning of the Pliocene was evidently highly complex in origin and of Metres oO /0 20 | r it | SSS See ATT ET Z SS = Diagram drawn to scale, showing development of columnar jointing in Tertiary basaltic flow near Ducks station. The gently dipping limb of the syncline is composed of regular columns of great size. The upturned limb is composed of four sets of regular but much smallercolumns. The latter seem to have developed through orogenic stresses superposed on original cooling stresses. great variation in age. Large areas had been undergoing erosion since the closing days of the Paleozoic; other areas, since the Triassic; others, since the late-Jurassic revolu- tion; still others, since the Laramide revolution; while practically the whole Cordillera, except the part covered by Tertiary volcanics or local pockets of earlier Tertiary sediments, was being eroded during Eocene, Oligocene and Miocene times. We may well believe that, in places, the unceasing erosion of the whole (pre-Pliocene) Tertiary era, in spite of post-Oligocene deformation, had virtually pro- duced local or widespread peneplains. Elsewhere moun- 164 tain torsos must have been the rule, except on the lava plains. In short, the early Pliocene Cordillera was a torso landscape, locally veneered with, and smoothed by, basaltic floods. It was this topographic composite, already close to sea level, which early Pliocene erosion somewhat further reduced toward a base level of fairly constant position. Toward the close of the Pliocene all or nearly all of the Canadian Cordillera seems to have been elevated, to heights varying considerably, but reaching maxima of from 2,000 to 4,000 feet (610 to 1,220 m.). The streams so rejuven- ated have had time to sink deep valleys in all three of the great Cordilleran Belts. This two-cycle topography is specially well illustrated in the Belt of Interior Plateaus, but it can be discerned in the Rocky Mountain trench, in the region around Revelstoke, and elsewhere along the railway section. The plateaus of the interior have been thus iso- lated from one another. In part, they represent dissected lava tables; in part, dissected local peneplains of pre- Miocene date; in part, dissected mountain torsos, reduced during the early Tertiary and the Mesozoic. There is no evidence that a general peneplain was developed over this part of the Cordillera at any time; nor is it proved that the upland facets of the Interior Plateaus were due to general peneplanation of that broad belt in late Miocene and early Pliocene time. A superficial study of the Interior Plateaus might lead to that conclusion; in reality, the upland relief has been conditioned by several pre-Miocene erosion cycles. The Pleistocene glaciers gradually overwhelmed a mature to sub-mature topography. Their work represents a chapter of Cordilleran history already sketched; some of its details will be noted in annotations on the route to be followed by the excursionists. The recent changes in the late Glacial landscape are relatively slight and for the most part are too obvious to need formal statement in this place. SPECIALLY NOTEWORTHY FEATURES. In the midst of a multitude of problems and ascertained facts, certain aspects of the Cordilleran geology are worthy of special attention. Some of these are here listed for the convenience of the excursionists. 165 1. The great development of Cambrian sediments; their extraordinary richness in fossiliferous horizons and in new species and genera; the perfection with which some of this fauna has been preserved. 2. The unusually complete exposures and vast thickness of the Beltian system of rocks conformably underlying the Lower Cambrian. 3. Illustration of geosynclinal prisms of various ages. 4. The large area of pre-Beltian (‘‘Archean’’) forma- tions, including sediments, volcanics and orthogneisses. 5. Specially clear illustration of the efficiency of static metamorphism (Shuswap terrane and Beltian system). 6. The wide extent and great thickness of basic vol- canics referred to the Triassic and to the mid-Tertiary. 7. The section through the Coast Range batholith, probably the most widely exposed intrusive mass of post- ““Archean’’ date. 8. The evidences of a chemical origin for limestones and dolomites thousands of metres in thickness. g. The opportunity of passing through the Rocky Mountain Geosynclinal into the terrane which furnished most of its clastic materials. 10. A view of the important unconformity at the base of the Rocky Mountain Geosynclinal. 11. The sections through the Rocky Mountain and Purcell trenches, two of the more remarkable depressions in the North American Cordillera. 12. The nature of the railway section as favourable to the discovery of field facts showing the relative shallow- ness of the earth-shell involved in orogenic folding. BIBLIOGRAPHIC NOTE. The most comprehensive guides to the geological litera- ture dealing with the railway section of the Cordillera are :— General Index to the Reports of Progress, 1863 to 1884, Geological Survey of Canada; compiled by D. B. Dowling, Ottawa, 1900. General Index to Reports, 1885-1906, Geological Survey of Canada; compiled by F. J. Nicolas, Ottawa, I9o01. Summary Reports of the Director, Geological Survey of Canada, 1907 to 1912, inclusive. 166 Indexes to North American Geology; Bulletins No. 127, 188, 189, 301, 372, 409, and 444 of the United States Geological Survey. In these most of the important publications will be found under the names— G. M. Dawson, McConnell, McEvoy, Camsell, Walcott, Allan, and Dowling. Especially to Dawson, the master in reconnaissance, geology owes the broad outlines already fixed for the Canadian Cordillera. A useful summary of its geology with leading references, is Dawson’s ‘Geological Record of the Rocky Mountain Region in Canada,’ published in the Bulletin of the Geological Society of America, Vol. 12, 1901, pp. 57-92. His report on the Area of the Kamloops Map-sheet (427 pages) in Volume 7 of the Annual Reports of the Geological Survey of Canada is the most detailed work yet published on any large part of the railway section. In Volume 53 of the Smithsonian Miscellaneous Collections (1908), will be found C. D. Walcott’s principal writings on the Cambrian and pre- Cambrian geology of the Rocky mountains in Canada. The more important maps referring to the section are :— Reconnaissance map of a _ portion of the Rocky Mountains between latitudes 49° and 51° 30’; by G. M. Dawson, Geol. Survey of Canada, 1886. Shuswap sheet; by G. M. Dawson, Geol. Survey of Canada, 1898 (not issued). Kamloops sheet; by G. M. Dawson, Geol. Survey of Canada, 1895. Geological map of the Dominion of Canada; Geol. Survey of Canada, IgoI. The references in the text of the Cordilleran portion of the guide book are to the following publications :— 1. Dawson, G.M....Geol. Surv. Can., Rep. of Progress, 187 7—70- 2. McConnell, R. G.Geol. Surv. Can., Ann. Report Vol. II, Part D, 1886. 3. Dawson, G. M...Bull. Geol. Soc. America, Vol. 2, 1891. 4. Dawson, G. M...Geol. Surv. Can., Ann. Report, Vol. VII, Part B, 1894. 5. Dawson, G. M...Bull. Geol. Soc. America, Vol. XII, I9OI. GaeWhlllistes\ ae ae Bull. Geol. Soc. America, Vol. XIII, 1902. 167 7. Walcott, C. D....Smithsonian Misc. Coll., Vol. 53, 1908. 8. Penhallow, D. P.Geol. Surv. Can., Report on the Tertiary Plants of British Columbia, 1908. 9. Shimer, H.W.....Geol. Surv. Can., Summary Report 1910, Lake Minnewanka section. 10. Walcott, C.D....Smithsonian Misc. Coll.: Vol. 57, INI@Ss: 2, 35 Gr Oh 8 MUO 11. Daly, R. A.......Geology of the North American Cordillera at the Forty-ninth Par- allel, Geol. Surv. Can., Memoir No. 38. ROCKY MOUNTAINS (Bankhead to Golden). BY JoHNn A. ALLAN. STRATIGRAPHY. COLUMNAR SECTION. In the section across the Rocky mountains, between the Cascade trough near Banff to Golden and the Columbia valley, all the geological systems from the Pre-Cambrian to the Cretaceous inclusive, except the Triassic, are repre- sented. As shown in the tabulated section given below, the stratified rocks aggregate more than 52,628 feet (16,040 m.) in thickness. The thin-bedded strata, mostly shales, make up 23,730 feet (7,235 m.); the limestones, 20,528 feet (6,255 m.); the quartzites and sandstones, 8,370 feet (2,550 m.). The relation between the Silurian and the Devonian systems is not shown in this area, because the Cambrian, Ordovician and Silurian formations are exposed mainly on the western slope of the Rocky mountains, while the remaining systems are exposed wholly on the eastern side of the Continental watershed. 35069—5A 168 ‘sJUSUISeI] dYI[-SUV] OUT STOY]eIM ‘ajeys snosoeusie yoRjq 0} UMOIq YIeq ‘ajeys pue ouo0Jspues UMOIG Poppeq-uTY |, “SUIBAS [LOD YIIM V[eYSs pue sUOJspues ‘qUO}SpuUes JO spueq piey y}IM sjeys pue suO}spues poppoeq-ury | ‘sax Ap YIM ‘9Ja ‘aqisuemdnoel ‘az171n ‘ayyolt ‘aquaAs optpoydan TEL ‘dJVIOUIO]SUOD pue yIS ‘ARID ‘pues ‘JaAeI4y ‘pues ‘JaAeIry “AZOPOUNT +LSb +00 ‘I +Sof +000‘I +¢S9 +008 ‘z +891 {+088 *SoI19IN 7094] “SSUNMOIH IT, "xOuddy eC ee ayeys dIUto suo0Jspues pouogqry J3aM07] "*sainseoul [vod Aeua}00y auojspues pouoqqry todd ed YOoI snoous] ‘IID{ANS UOLSOLT Y Oo Ur0 0-0 Gp OOOO 0800, Co yenery O16 CO DIO) 0 0'O dUIIASsNIe’T] “UOT}EULIO J ee ew ee we oissein [ ee ee SNOVde}oO1°) ¢SNOIdP}01°)-}SOg *9U990}S19[ pue jUI0y “UWI9}SAS ‘SNOILVWUO.Y JO ATAVL ON Ne) e *poppeqsoiUr oyeys YIM ‘aTYM 0} AvI3 WS] Suroy}yeoM sayizyienb pue so}wWo0joOd YSIMO]J[OA puke YSTUMOIG PUB SIDAP] JUL}SISOI SSd] YIM Popposqsa}UrI VUO}JSIUN] Peppoq-uly L “QUOJSOUN] SNODOITIS pue o1w0jop Avis jo s1sAR] VAISSeU 9IOUI SUI}eUIOYe YIM ‘SsouoSOUIT] *suOT}e30139S II}IWO[Op SNOJOUINU YIM SouoJsouTT] AIS pappeq-yoIYy L ‘UMOIG IYSI] SULIOyIeIM ‘snosIRo[e pue snosoryisie ‘ayeys Avis yrep 07 Yyorg -Idy}PIM ‘apeys pue 9UO}sSOUIT] Pappaq-uIy Aq urepiapun sioAey Asay uTYy} snosownu YM souojsou, AeIS YIep peppeq-xoIy LT, *QUO}SOUN] SNOVOITIS snosdeueie pue oyzyenb Avis 0} oY M 2 spaqisalisnjey (é 938) DUOJSAUNT] YOVQMeS “*** Quo SOUT] 9} CIPIW19}UT “URLINIIS “UMOUY JOU SUOLIDIAL JIDJUOJ— Seas LET ONO (il pee cere duo} sou] Ue, JOMO'T Boca .o-o.0 DO ayeys yueqd JOMO'T cceacgts quojsouny yueg toddyq ‘oqizqaenb urequnoyy AYI0Y ‘ystmoyjad pue ystppor ‘aJeys snovsdeuatie uUMOIq Y1Ieq +96 +09 ‘1 -ayeys +Lz1‘1t |+ooZ‘¢ poppeq-ulyL|+srS |+00g't +Lov +o0$ ‘1 +99¢ 007 ‘I “AviS SUI +102 +o0¢‘z +z 008 +lev +ooh ‘1 SULIOYIeOM CCC ajeys yuegq Joddy nee ee uelueAlAsuuag BOR eres ueiddississt JA] UPIWAIIg 1 524 35069 ‘agjdind pure MmoyjjeA ‘par ‘surrayyeoM ‘qjeys snosoyIs ysis YUM poppaq -IoJUI {ynq ysImoyjaA Suroyyeam au0}s -OUIT] SIJTWO[Op pue snosdeuare Avid aAIsseyy|+ SoS eS Keg Ua Rosteaeairegreet a C.D * YyQIOMsog ‘QUOJSOUNT] IIYIWIO[Op Jo spueq DIPJOO yyWM ‘squOjsoUT] AVIS YSIN[q vAIssey[|+ O11 ea (O10 oe sat EOL EEE yoseg *SoUO}SOUI] DIIWOTOp JO snosdeuaIe ‘d11]00 peppoq-ulyy) 61P VAS Ge eer uae Orde adyOoIq1ayS “Ag][VA ][1e1101IQ ul soqAyd pue soqy]]Id1e ‘soqejs ‘sayeys Aeis poreoys Alysty Aq UlejJopuN uM] pue YSsIMOTad ‘ysIppar Sur -Iay}eIM {SaTeYs puv Soj]][IS1e-eJIUI SNOdIeI -[eo pue snosoeypisie Avis poyeurmeyl Ayu p|+cZE'1 |+o006'V jos Jo]JaoueYy) ‘spueq Ayeys pue Ajyoyo YUM soUO sou] onjq sarsseyy|+9cS SG COON is sees otc dUO}SOUIT] |1e.I9IIO) "°° ueliquie) 1oddq ‘so[eys pue Sa}¥IS SNOdIeI[eD pue SNoOddI]IS ‘squoJSOW] ~OTTWO;Op pue Ajayo ‘syoyD)/+cehg‘i |+obo'g |-°°+ +++ +++ apeys aspooy “soTeys o]Issy UMOIG pue yor|g|+ 81S SOO LE Genet rie sayeys oyyoydery}* UPIDIAOPIC) ‘saya | “97 *ASOjOYWT “U01]eUIO "U94SAS *“SSANMOIH[L, *xOuddy *“papnjIu0jJ—SNOILVNAOY AO ATAV IAL +10‘91 +gz9'zs ‘poppoqiequr apeys "+ *SsaUyoIy} [210 ‘pasodxa Jou aspg YUM oOJspues pouTe1s-ds1vOo pue dI7Iz1IeNG)| Lor OCT |e" Hei seats des YooIZ [esI0OD *‘poppaqioj}UI 9} eIJOUIO[SUOD YUM geys snoaoyis ojdind pue useis ‘Ae1y/4 66E'1 [+ 06G'V Joo JO] 591] ueliquie)-o1g saapjg aos ur ajqnusofuo) “guUO}Spues pourei8-ss1e0oo ~pue o}esowo;su0D = [eseq jes0yJ ‘auojspues o1jIzJAeNb— snoursnssay| CRI SE OOOia: 6h keke Mase aie: MOTAIIC LT ‘gyeys snosoris ystAeis yoeduroy) ze Sol ie toe ee eee OSTNOg_O Ca) ‘quojspues o1}1ZJIeNb snoursn44194|4+Vzg GOLIG Reson cecccoccasontienits] AXS “QUO JSOUT] peppeq-ury} pue guoyspues ‘ayeys snovdI]IS) 611 OOS, Ae eee ae AY AA “IIA UeLIquied JomoT *sou0js -dWIT] OIJIWIOJOp pue snoasdvuaIe poppeq-uIy]| 9gP SO SRST Nica sues oc ss ate tet [erpoyieD ‘PPM “VA UE, areys ssoding.,, pue uoydais 3y Ul ,,ayeys stsdosAsQ,, sepnpour ‘fayeys pue ‘auojsoully] pappoq-ulyy| 961 OVO Soe sated comer: oo uoydoqs "S8V1O po}R]JOISeO pue s}pijo Sur -WJOJ SOUO}JSOUNT] SNODDvUDIe Pappaq-aAIsseI| £8 CAIN A | eg mou cs came ae uOp] A] UeTquUIeD eaPPII 172 RESUME OF SECTION. Cretaceousscicehat. ca) alee een ty ae erage 4,350+ 1,326 JUTASSICS ces eee ach os alse sani ey oe eene oe eae eerreiee ee 1,500-+ 457 IPeriiianins 2 tsa) eae ae eet een Ae ah ee 1,400+ 427 Carboniferous ccc 0: Bee. eth eee eee 5,800+ 1,768 Devonian. Mai ae esa etl eas oe Re eee nen 1,800+ 548 Devonian (es 5 ee A eee Ae ate ai ee 3,700+ 1,127 Silurian e gh es ae ee tah ee ee earnete 1,850+ 563 Ordovician. bee eek ee cee eee 7,740+ 2,360 Upper Cambrian, 220 22.5 en a eee 9,815+ 2,992 Middlei@ambrians- es see coe Oca eee 4,963 1,513 Lower Gambrianian: Are en See eae eee oe 3,800+ 1,158 Pre-Cambrian is (S05. chase eee 5,910+ 1,802 Po tallicc succes aie pee oan ee one ee 52,628+.16,041-+ PRE—CAMBRIAN. The Pre-Cambrian series is distributed along the floor and sides of Bow river valley from the base of Castle mountain, where it becomes faulted off against the younger Paleozoic rocks, to the head waters of the Bow river. The contact between the Pre-Cambrian and the Cam- brian is seldom exposed. It was examined at three locali- ties. At one exposure in Bath Creek valley, near the summit of the Rocky mountains, the contact is a conform- able one, while in two other localities in which the contact was exposed, there is a noticeable unconformity between the beds of the two systems. In one case the Pre-Cambrian shales were dipping 31 degrees S. 55° W., and the Lower Cambrian quartzites had a dip of 35 degrees Ss 5a. The rocks in the Pre-Cambrian series, with the three lowest formations of the lower Cambrian, were formerly called the ‘Bow River Group’ by McConnell [2, p. 20]. Corral Creek Formation.—This formation includes the lowest beds exposed in the Rocky mountains, along this section. This series consists of gray sandstone under- lain by a coarser quartzitic sandstone, with an arkose-like conglomerate at the base. The lowest beds are exposed in a railway cut two miles (3,249-2 m.) east of Laggan station. This rock is made up of small pebbles and grains of quartz, and angular crystals of white and pink feldspar. The cement is made up of finer material of EXCURSION C I. Contact of the Pre-Cambrian shales (Hector) and the Lower Cambrian quartzites. Exposed in Bath creek west of Laggan. 174 the same composition. The nature of this rock suggests shallow-water or near-shore conditions of origin. Hector Formation. The beds in this formation consist of gray, purplish, and greenish shale interbedded with bands of conglomerate 15 m. to 75 m. thick. The best exposure is in the Bow range east of Storm mountain, where the formation has a minimum thickness of 4,590 feet (1,399 m.). It thins out towards the northwest; in Mt. Temple, Walcott measured over 2,150 feet (655 m.), and at Fort mountain towards the head of Corral creek he obtained a section 1,302 feet (397 m.) thick. From one layer of shale (50 cm. thick), outcropping on the eastern base of Storm mountain and about 16 metres from the top of the series the writer collected fossil remains of a brachiopod-like shell about one-eighth of aninch in diameter. This is the only locality in which fossil remains have yet been found. CAMBRIAN. The Cambrian series is complete in this section with both lower and upper contacts exposed. There is a total thickness of over 18,578 feet (5,663 m.). This represents one of the thickest Cambrian sections yet measured in the world. It essentially consists of 3,800 feet (1,159 m.) of siliceous beds, principally quartzitic sandstone; 10,275 feet (3,132 m.) of calcareous and dolomitic limestone, and 4,500 feet (1,371 m.) of shale, much of which is calcareous. The various divisions of the Cambrian series have been made on paleontological and lithological evidence. The formations in the Lower and Middle Cambrian and the first three in the Upper Cambrian were named and meas- ured by Walcott, [7, p. 204]; the remaining two formations were named and measured by the writer. LOWER CAMBRIAN. Fairview Formation.—The Fairview formation con- sists of brown and white quartzitic sandstone. Locally there is a basal conglomerate on the Pre-Cambrian shales; it consists of rounded pebbles of white quartz, up to 7 cm. in diameter, in a cement of quartz, feldspar and mica. The basal rock is more frequently a coarse sandstone with rounded and angular grains of quartz and feldspar, 175 5 to 15 mm. in diameter. Some of the quartz grains have a glassy, almost opalescent colour. Lake Louise Formation.—As the name indicates, these beds are best exposed at Lake Louise. The formation has a total thickness of 105 feet (32 m.) and consists of a ferruginous siliceous shale. It weathers more readily than the beds below or above, so that the slopes are more gradual. Mt. Temple, showing a complete Lower and Middle Cambrian section capped by Upper Cambrian, and underlain by Pre-Cambrian shales (covered by talus). St. Piran Formation.—This formation consists of massive-bedded, ferruginous, quartzitic sandstone, with a total measured thickness of 2,705 feet (824 m.). These beds form steep escarpments wherever they are exposed. On the west side of Mt. Victoria the cliffs composed of these beds are over 2,500 feet high. The brown color of the rock is due to smoky quartz and small particles of mica in the cement. Mt. Whyte Formation.—In sharp contrast with the underlying massive quartzites, there is a thin series of siliceous and calcareous shales grouped as the Mt. Whyte formation. ‘These shales are less resistant than the quart- zite and form gradual slopes. Some of the layers contain numerous annelid borings and trails. 176 MIDDLE CAMBRIAN. Cathedral Formation.—This formation consists of massive and thin bedded dolomitic limestone, which on the weathered surface becomes buff and gray. The more massive beds are arenaceous in their composition. It is on this formation that the Monarch mine in Mt. Stephen is situated, and other small mineral prospects in the Kicking Horse valley. Castle Mountain, showing Cathedral limestone in the lower cliffs; Stephen formation in the talus covered slope; and the Eldon formation in the upper cliffs. (All Middle Cambrian). Some of the limestone has become metamorphosed into marble. One of the best exposures of this rock is in Cathedral mountain, four miles (6-4 km.) east of Field. Stephen Formation.—Although this formation is only 640 feet (196 m.) thick, yet it is quite important for the number and variety of fossils which it contains. It consists of shaly limestone and calcareous shale. These beds include the ‘Ogygopsis shale’ in Mt. Stephen, and the ‘Burgess shale’ in Mt. Field, on the opposite side of the valley. The former includes the widely known trilo- bite-bearing ‘fossil bed,’ while the latter includes the new ‘fossil bed,’ discovered by Walcott in 1910. From this bed he has obtained an extensive variety of Middle Cambrian organisms. Coelenterata, Annulata, Echinoder- EXCURSION C I. Fossil bed in ‘‘ Burgess shale’ on Mt. Field, showing character of the shale, method of quarrying for fossils, and temporary camp of C. D. Walcott. 178 nol and certain Arthropoda are abundantly represented Eldon Formation.—This formation has a thickness of 2,728 feet (831 m.) where it was measured in Castle mountain. It consists essentially of massive-bedded, arenaceous limestones, which form steep castellated crags on the erosion surface, thus making the formation readily recognizable wherever exposed. It is this formation which forms the steep escarpment about the upper part of Castle mountain. The Mitre and Death Trap (pass) to the right. The cliffs on the right are of Middle Cambrian limestone in Mt. Lefroy. A typical bergschrund is shown around this portion of the Lefroy glacier. UPPER CAMBRIAN. Bosworth Formation.—This formation is exposed in the mountain of the same name on the Continental Divide. It consists largely of thin-bedded limestone with a few more thick-bedded layers, interbedded with siliceous and arenaceous shale. One band of shale makes a good horizon-marker because it weathers greenish, yellowish, deep red, and purplish. Paget Formation.—A band of grayish odlitic lime- stone, typically exposed in Paget peak, on the west slope of Mt. Bosworth, has been placed in this formation. These beds can not be readily distinguished from the underlying limestone. 179 Sherbrooke Formation.—Arenaceous limestone at the base of this formation is overlain by thin-bedded limestone, including some od6litic and shaly layers. This formation includes the highest beds exposed in the Bow Range in the vicinity of Hector Pass. The remaining Cambrian formations, the Ordovician, and the Silurian are all exposed in the western portion of the section between the Bow range and Columbia valley. Chancellor Formation.—This formation consists essen- tially of shales which weather reddish, yellowish, fawn or gray. The uppermost 2,500 feet (762 m.) are gray met- argillites, well cleaved along the bedding planes, and weathering reddish and yellowish. These shales become much more highly cleaved towards the base of the forma- tion, so that the lowermost, 2,000 feet (610 m.) thick, consist chiefly of phyllites and slates, with argillites and a few interbedded layers of shaly limestone. The fer- ruginous content in all the beds is high, so that the weather- ed surface is usually reddish or yellowish. This series floors Ottertail valley, underlies the Ottertail range, and makes up a large part of the Van Horne range. Ottertail Limestone.—This formation consists almost entirely of blue limestone, massive towards the top and rather thin-bedded towards the base. It has a thickness of over 1,725 feet (526 m.) in the Ottertail range, where it is well exposed in an almost perpendicular escarpment along the east side of the range. The cliff-forming char- acter of this formation marks it off very sharply from the shale formations below and above. This limestone represents the highest series in the Cambrian in this portion of the Rocky mountians. ORDOVICIAN. Goodsir Shales.—This formation is best exposed in Mt. Goodsir, where it has a measured and estimated thickness of over 6,040 feet (1,841 m.). It lies conformably on the Ottertail limestone and consists at the base of almost 3,000 feet (914 m.) of alternating hard and soft bands of argillaceous, calcareous, and _ siliceous shale, which weather light yellowish, gray and buff. The upper part of the formation consists of banded cherts, cherty limestones and dolomites, thin-bedded and 180 “very dense, so that they weather into compact angular fragments. The beds in this series become very highly sheared in the Beaverfoot valley and the range to the west. On both paleontologic and lithologic evidence the boundary between the Cambrian and the Ordovician in this district is placed at the top of the Ottertail limestone and at the base of the Goodsir shale. Cambrian—Ordovician contact in Mt. Goodsir. The gray rock is the Ottertail lime- limestone, overlain by the dark-colored Goodsir shales. Fossils were found near the base of the Goodsir forma- tion at several localities, and have been determined by Walcott. The following new species have been identified from this series. :— Obolus mollisonensis. Lingulella? allani. Lingulella moosensis. Ceratopyge canadensis. The presence of the Ceratopyge fauna places this forma- tion at the base of the Ordovician, corresponding to the horizon of the Ceratopyge shale in Sweden. The sedimentary series from Mt. Whyte to Goodsir, inclusive, were included by McConnell in his Castle Mountain group. 181 Graptolite Shales.—These beds have been so named by McConnell on account of the richness of certain layers in graptolites. The presence of this fauna determines the age of the formation as Ordovician. The Graptolite shales consist of black, carbonaceous, and brown, fissile shale at the top, underlain by gray shales which grade into the underlying Goodsir formation. The thickness of the formation varies and the lower contact is ill-defined, but a thickness of at least 1,700 feet (518 m.) is represented. These shales occur as two infolded bands in the Beaverfoot range. SILURIAN. Halysites Beds.—The Halysites beds consist chiefly of dolomitic limestone and white quartzite. This forma- tion lies conformably upon the Graptolite beds. The character of the rock sharply distinguishes it from the older strata. The formation is terminated above by a fault contact or by an erosion surface. A measured section gave 1,850 feet (563 m.). The white quartzite is over 900 feet thick (274m.). It is infolded with the graptolite beds in the Beaverfoot range. Some of the beds of dolomitic limestone are highly fossiliferous; corals are most abundant, but crinoids, brachiopods, and gastropods are also present. This is the youngest formation exposed to the west of the Continental Divide, along this section of the Rocky mountains. DEVONIAN. Intermediate Limestone.—This formation consists of thin-bedded limestones, alternating with harder layers of gray dolomitic and siliceous limestone, which on the weathered surface becomes banded. In the Sawback, Vermilion Lake and Cascade ranges it is exposed, being repeated by reversed faulting. The thermal sulphur springs at Banff occur in the Intermediate limestone. The rock is high in sulphur, derived by the decomposition of pyrite which the lime- stone contains; a strong odor of sulphide of hydrogen is given off when the rock is struck with a hammer. Some of the beds are highly fossiliferous. Zaphrentis and brachiopods are the most abundant forms present. 182 The upper limit of this formation is not clearly defined as it is transitional into the Lower Banff shale. — Sawback Formation.—Underlying and conformable with the Intermediate limestone is a series of massive and thin-bedded, dolomitic limestone and shale, which Mc- Connell has placed in the Cambrian. These form a wedge-shaped band in the Sawback range and lie between Mt. Hole-in-the-wall and Mt. Edith, with a broader exposure along the north side of the Bow valley. It has been possible to measure and estimate a thickness of about 3,700 feet (1,128 m.) but the actual thickness is believed to be much greater. Fossils have not yet been found in this series. Since they differ lithologically from the Cambrian beds in Castle mountain, which are largely Middle Cambrian, and from the Cambrian in the Bow range and to the west of this range, it is proposed to call this series Sawback limestone. The age of the formation is still in doubt but it is older than the Inter- mediate limestone, which is definitely known to be Devon- ian in age. These beds are lithologically closely related to some of the Silurian beds in the Beaverfoot range to the west. MISSISSIPPIAN. Lower Banff Limestone.*—This formation grades into the Devonian limestone below, so that it is not possible always to draw a sharp dividing line between these two formations. It is quite clearly defined on its upper con- tact, as the overlying formation is a shale. The beds consist of massive-bedded, gray limestone which forms steep escarpments wherever exposed on the slopes of a mountain. This limestone forms the eastern cliffs of Cascade moun- tain, and Mt. Rundle; and the steeper eastern slopes of Sulphur mountain. Some beds are fossiliferous, and the formation is characterized by numerous fossil-like dolomitic segregations. Many of these resemble certain types of bryozoan remains. Lower Banff Shale.—There are about 1,200 feet (366 m.) of shale included in this formation. These shales are black to dark gray in colour and weather brown. *Since Dr. Allan sent his MS. to press, Dr. H. W. Shimer has found that the fossils recently collected in this limestone show it to be largely if not wholly of Devonian age. 183 They are usually calcareous in composition, but certain layers are argillaceous and arenaceous. The lower contact of this series is sharply defined but at the top of the series the beds change to a shaly limestone difficult to distinguish from the overlying limestone. The shales weather out more easily than the limestone, so that a depression is always formed where these shales cut across a ridge. A leading fossil is Spirifer centronatus. PENNSYLVANIAN. Upper Banff Limestone.—There are over 2,300 feet (701 m.) of beds included in this formation, which is well exposed in Sawback and Cascade ranges. The series is shaly at the bottom, but more massive towards the top. Cherty lenses and cherty shale interbedded with the lower shaly limestone help to distinguish this formation from the shales below. Fossils e.g., Spirifer rockymon- tanus, are quite abundant throughout the lower beds in this series. Rocky Mountain Quartzite.—This quartzite lies directly on the Upper Banff limestone. It represents a very sudden shallowing of the water, which, however, was not rendered muddy. The section in the Sawback range gave 800 feet (244 m.) as a maximum thickness. There is a rapid thickening of this formation to the east so that at Lake Minnewanka, 12 miles (19 km.) to the east, there are 1,600 feet of quartzite exposed. Certain portions of the formation are quite fossiliferous. These fossils e.g., Euphemus carbonarius, can most readily be found on the weathered surface. This is the uppermost formation in the Carboniferous. The lower two formations have been grouped as Mississip- pian in age, while the upper two correspond to the Penn- sylvanian. [9, p. 147]. PERMIAN. Upper Banff Shale.—This formation lies conformably upon the quartzite and consists of a series of brown, calcareous and arenaceous, often sun-cracked shales interbedded with thin layers of sandstone. The shales weather out more easily than the underlying formations, forming valleys such as those between the Cascade, Ver- milion Lake, and Sawback ranges. More than 1,400 feet 350690—6A 184 (427 m.) of strata are represented in this section, but it is difficult to get an accurate measurement on account of the foldings and contortions within the beds. A leading fossil is Schizodus. A typical view of the Upper Banff shale, exposed in Spray valley at Banff. JURASSIC. Fernie Shale.—No sharp line can be drawn between the Upper Banff and Fernie shales, except where fossils are found. The Fernie formation consists of black and dark brown, siliceous, very thinly laminated shales which break up into small fragments on the weathered surface. West of Banff it has a limited distribution, lying on the Upper Banff shale. East of Banff and on the north side of the Cascade trough, it forms a band about 1,500 feet (457 m.) thick. The Fernie shale was examined near Exshaw 6 miles (9-6 km.) east of the Gap. A certain layer was found to contain clay concretions of which the largest was 35 cm. in diameter. Another layer, 15 cm. thick, contained numerous bone fragments. One large reptile-like jaw-bone is 22 cm. long. There are many smaller fragments of bone and teeth. Ammonites are very common in the Fernie shale. 185 CRETACEOUS. Lower Ribboned Sandstone.—The Cretaceous beds are exposed along the eastern base of Cascade mountain. The Lower Ribboned sandstone consists of alternating bands of brown-weathering sandstone and shale. This formation follows the bottom of the Cascade trough and is exposed on the road between Bankhead and the west end of Lake Minnewanka. The beds are here about 1,000 feet (305 m.) thick. Kootenay Coal Measures.—This formation consists of 2,800+feet (853-+m.) of sandstone and shale enclosing several workable seams of coal. There are fourteen seams exposed at Bankhead, where the coal is being mined, and nearly twice as many have been found at Canmore down the Cascade trough. The coal is bituminous and anthra- citic. Several of these seams are being mined at Canmore. The coal measures are well defined between two massive sandstone bands which form roof and floor. Upper Ribboned Sandstone.—This formation con- sists of thin-bedded sandstones and shales. It is exposed at the eastern base of Cascade mountain. The beds are wedged between the coal measures below, and a thrust plane above. Some of the uppermost Cretaceous beds were planed away when the older beds were thrust over them. There are about 550 feet (168 m.) of beds exposed in Cascade mountain, but this formation becomes thicker where it is exposed to the northwest and southeast of this section. POST-CRETACEOUS. Igneous Complex.—The only igneous rock in the Rocky Mountain section is represented by the Ice River intrusive complex, which has the form of an asymmetrical laccolith with a stock-like conduit. It has an area of about 12 square miles (31 sq. km.). The rocks of the complex are all alkaline in composi- tion, ranging from nephelite syenite and sodalite syenite through urtites and ijolites, to a jacupirangite or alkaline pyroxenite. These diverse types represent a complete petrographic series with intermediate facies. The age of the intrusion is believed to be post-Creta- ceous as determined by structural and correlation evidence. 35069—63A 186 PLEISTOCENE AND RECENT. The unconsolidated material is represented by three types of deposits as shown in the section. The fluviatile and lacustrine deposits appear in terraces about the sides of the larger valleys, while the former also floors the broad flood plains of the main streams, such as the Bow, the Kicking Horse, the Beaverfoot and the Yoho. Glacial till veneers the more gradual slopes of the various ranges, to an elevation at least 9,000 feet (2,743 m.) above sea-level. Miles and Kilometres. 79°5 M. ANNOTATED GUIDE. (Bankhead to Golden). BY Joun A. ALLAN. Bankhead—Alt. 4,510 ft. (1,375 m.). 127-2 km. This station lies to the western edge of the from Calgary. Cascade coal basin described by Dowling [1]. About one mile east of this siding the railway leaves the bottom of Cascade valley and, turning at 90 degrees to the southwest, passes between Cascade mountain on the north, and Tunnel mountain on the south. This was at one time the course of Bow river, but the channel was obstructed by the gravels brought down by Forty Mile creek, as well as by the moraine left by the continental ice sheet, so that now the Bow passes through this range between Tunnel mounta‘n and Mt. Rundle. The structure of the beds in Cascade moun- tain is well shown in the cliff to the right of the railway. The beds are steeply dipping to the west and terminate in a precipitous cliff on the east. The cliffs at the base are Intermediate limestone (Devonian), overlain by Lower Banff limestone (Lower Carboniferous). The Lower Banff shale above (also Lower Carboniferous) weathers into talus-covered slopes. The moun- tain is capped by Upper Banff limestone and Miles and Kilometres. 187 Rocky Mountain quartzite (Upper Carboni- ferous). An overthrust fault-line scarp defines the steep eastern face of this mountain; the Devonian limestones are thrust over the Cretaceous coal measures. This fault-line de- fines the southwest side of Cascade valley. It is exposed in the base of the Three Sisters, and extends to the southeast along the eastern face of the Livingstone range at the Crowsnest Pass, and into Montana, where it is known as the ‘Lewis thrust.”’ It has not been possible to measure the actual amount of displacement, but there is a vertical throw of about three miles (4-8 km.) in Cascade mountain. Mc- Connell [2] has estimated that the front ranges of the Rocky mountains have been thrust about seven miles (11-2 km.) over the plains to the east, but it it not possible to measure the horizontal displacement in the Cascade Mountain thrust fault. A spur runs from Bankhead station to the Bankhead coal mines, about two miles (3-2 km.) to the northeast. These mines are owned and operated by the Canadian Pacific Railway Company. They are situated in the Kootenay coal measures which are Lower Cretaceous in age. The coal is bituminous and semi-anthra- cite. The plant is well equipped with a large breaker and a briquetting mill. Between the coal mines and Lake Minne- wanka a section along Cascade river exposes Cretaceous, Jurassic, Permian and Upper Car- boniferous beds. This section has been studied in detail by H. W. Shimer [3]. Fossils are abundant, expecially in the Rocky Mountain quartzite. For a portion of this distance the driveway follows along the top of a morainal ridge. In Pre-Pleistocene time Cascade river drained out by Lake Minnewanka and Devil’s Gap to the plains, but in recent time it has cut through the thick morainal detritus and has joined Bow river four miles (6-4 km.) east of Bankhead station. Miles and Kilometres. 82 m. 188 Banff—Alt. 4,521 ft. (1379 m). This is the 131-2 km.gateway to the Rocky Mountain National Park. This reservation covers 5,732 square miles (14,330 sq. km.), and contains many features of interest. Some of those to be visited are the hot sulphur springs, sulphur caves, Sulphur Mountain observation station, and the buffalo paddock. Looking west from the station are seen the snow-capped peaks of the Bourgeau range, ten miles (16-1 km). distant. The town lies west of Tunnel mountain. On the north side of the valley are Cascade mountain and a_ subsidiary ridge, Stoney Squaw mountain, in which is shown the eroded end of an asymmetrical anticlinal fold. A few yards to the west of the station Bow river turns sharply to the southeast, and after passing the town and cascading over a very picturesque fall, it is joined by the Spray. At this point, close to the Banff Springs hotel, the river is diverted at right angles to the east and passes between Tunnel and Rundle mountains. The valley of the Spray river is floored with soft Permian and Jurassic shales. The accompanying figure shows a typical view of the Upper Banff shale (Permian), exposed in Spray valley. This valley is defined by a fault so that the beds in Sulphur mountain repeat those exposed in Cascade and Rundle mountains. The Fernie _ shales (Jurassic) are characterized in certain layers by the abundance of ammonites. On the east slope of Sulphur mountain are situated the hot sulphur springs. The upper one is 500 feet (152-5 m.) above the town. The water comes from the orifice at a temperature of 114-2 degrees Fahr. (45-6° C). This sulphuretted water has a marked medicinal effect, and many people visit Banff on this account. A second or middle hot spring is 200 feet (60 m.) lower down the slope, and a mile and a half (2-4 km.) farther to the \ ce 7 gC " we?) , = g ae 2 / 4 As Kilometres 2 bets. ae ele eslie : i A at Legend Excursion C/. Glac/ers Quaternary Cretaceous Jurassic Permian Carboniferous Devonian Silurian Ordovician Opper Cambrian Middle Cambrian Lower Cambrian True North Pre-Cambrian Igneous Geological Survey, Canada. Fau/t E=-- [—] Geological boundary ‘Route map between Banff and Golden Z Miles co fA w nN Fo 5 20 — Kilometres 10 1S 20 25 30 ae 1 =“ n mal -S Miles and Kilometres. 83 m. 132-8 km. 85 m. 136 km. 189 northwest. The spring is not so strong as the upper one, and the temperature of the water isMaboOUt eOOmMraN(32-2-@) = A third: on lower spring is situated farther to the northwest and about 50 feet (15 m.) above Bow river. The water is at a lower temperature than either of the upper two. Locally this spring is spoken of as the ‘“‘Cave and Basin’’, because the spring rises into a cavern about 20 feet (6 m.) in diameter. By means of an underground channel it escapes to a natural basin formed in the calcareous tufa deposited. A second cave has been recently discovered a few yards farther up the slope. The interiors of these caves are coated with sulphur crystals. The Dominion Park Commission is erecting a_ substantial bath house at this spring for the accomo- dation of the public. Other warm springs are located in the bottom of Bow valley, about the Vermilion lakes. All of these springs are located in the Intermediate limestone (Devonian). From the summit of Sulphur mountain can be seen the general monoclinal structure of this portion of the Rocky mountains. The successive ranges from the Cascade valley westwards represent westerly dipping fault blocks, which have become tilted along the east side. On the north side of Bow valley the Cascade, Vermilion Lake and Sawback ranges form distinct units, the same _ beds being repeated in each of these ranges. Leaving Banff station the railway follows along the broad swampy valley of the Bow, on the right of which is a series of three small lakes, called Vermilion lakes. The range to the right is the Vermilion Lake range, in which are exposed the westerly dipping Devonian, Carboniferous, Permian and Jurassic beds. This creek follows a fault line which divides the Vermilion Lake range from the Sawback range. This depression leads to Edith pass, beyond which can be seen Mt. Edith, which is made up of vertically dipping Lower Banff Miles and Kilometres. 88 m. 140°8 km. 190 limestone. The steeply dipping beds on the west of this creek belong to the Sawback formation. This formation lies conformably under the Devonian Intermediate limestone, but the exact age is still doubtful, as no fossils have yet been found in it. Lithologically, a part of this series resembles the rocks of Silurian age in the Beaverfoot range to the west. To the south of the railway is the valley of Healy creek which extends to Simpson pass, and is the course followed en route to Mt. Assiniboine, the Matterhorn of the Can- adian Rocky mountains. Bow river has here a meandering course, some of the lobes having been cut through, to form oxbow lakes. Sawback.—Alt. 4537 ft. (1,384 m.). West of Banff the railway crosses the strike of the formations in the Vermilion Lake and Sawback ranges, but at this point the valley of the Bow turns sharply to the northwest and follows _ along the strike of the formations as far as 148-8 km. Laggan. The Carboniferous limestones dip at about 65° to the southwest, so that smooth cliffs formed along the bedding-planes are characteristic of the Sawback range. Mt. Hole-in-the-Wall, to the north of the station, is so called because it contains in its side a cavernous opening. This cave at its outer end is 50 feet (15 m.) in diameter, but becomes smaller behind as the floor rises. It is about 150 feet (46 m.) long and is situated, 1,500 feet (458 m.) above the railway, in the Lower Banff limestone. The position of the Lower and Upper Banff shales is always readily recognized by a depression on the surface. Massive—Alt. 4,600 ft. (1,402 m.). On the south side of Bow valley, Pilot mountain towers 5,000 feet (1,513 m.) above the railway. The base consists of Devonian limestone, and the peak is capped by Upper Carboniferous. From the Intermediate limestone in Fossil mountain, Io miles northeast of Laggan, the following Upper Devonian fauna have been determined :—Spirifer whitneyi Hall; Productella Miles and Kilometres. 96:2 m. 153°9 km. 99 m. 158-4 km. IQI hallana Walcott; Stropheodonta demissa (Con- rad), Schizophoria — striatula | (Schlotheim), Chenungensis var. arctostriatus (Hall), Phillips- astraea verrilli Meek, Syringopora cf. perelegans Billings, and other Devonian species. A few yards beyond the west end of the siding, the railway cuts through a down- faulted block of dark brown Fernie shales containing ammonites, which indicate that they are Jurassic in age. The upper part of Johnson creek separates Sawback range from Castle Mountain range. It follows in a fault valley. Four miles from its mouth the stream has been diverted to the south by the down-faulted block of Jurassic shales referred to above. From this point there is an excellent view of Castle mountain with its perpendicular cliffs and broad amphi- theatre behind. Castle—Alt. 4,660 ft. (1,420 m.), is situated at the base of Castle mountain. West of the station the railway follows along the base of this mountain for over 10 miles (16-1 km.). The eastern end of the mountain is terminated by a large pinnacle which, from the railway, resembles the ruins of a massive castle; hence the name. The accompanying illustration shows the character of the rock in Castle mountain. The upper slopes are Cambrian. It is capped by the thin-bedded red-weathering limestones and shales of the Bosworth formation (Upper Cambrian). The perpendicular cliffs at the top represent the Eldon formation. This is the type locality and this formation has a measured thickness of 2,728 feet (832 m.). The Stephen formation is about 600 feet (183 m.) thick, and forms a very flat talus-covered slope, while the Cathedral formation below is about 1,500 feet (458 m.) thick and forms a precipitous slope. These three formations are Middle Cambrian in age. The Lower Cambrian beds are largely quartzitic and form brush-covered, irregular slopes. Miles and Kilometres. 100 m. 160 km. 105:5 m. 170:4 km. 192 Castle was an active town with about 1,500 people in 1884-86, but is now deserted. The ‘“‘boom’”’ was caused by the discovery of copper prospects in Copper mountain directly south of the station on the opposite side of the valley. Mining proved a failure. And there is now only one of the old timers, James Smith, living here. There are numerous foundations on this flat, but most of the buildings have been burned or torn down. The Dominion government is building an automobile road across the Rocky mountains from Calgary to Golden. The road _ here crosses the railway and Bow river; it follows up Vermilion creek to the south, over the Vermilion Pass, and down Vermilion river to the Kootenay, thence into the Columbia valley and down to Golden. The road is nearly completed up to the pass, which, with an eleva- tion of 5,264 feet (1,605 m.), is the lowest pass in this part of the Rocky mountains. To the east of Vermilion Pass is seen the craggy cliffs of Storm mountain (altitude 10,309 feet) in the Middle and Lower Cambrian formations. The lower rounded ridges to the east are formed of Pre-Cambrian shales. The contact, appar- ently slightly unconformable, is exposed at the eastern base of Storm mountain. Eldon—Alt. 4,817 ft. (1,468 m.). The broadly rounded Bow valley is underlain by the softer Pre-Cambrian shales included in the Hector and Corral formations. The Pre- Cambrian beds floor the Bow valley and the lower slopes up to Kicking Horse pass, and to the head waters of Bow river. This series has been called Pre-Cambrian by Walcott [4], because the beds are largely unfossiliferous and underlie the Olenellus zone of the Lower Cambrian. These beds represent a portion of the Bow river group, defined by McConnell [5]. A few brachiopod-like fossils were found by the writer in a layer of Hector shale at the base of Storm mountain. Miles and Kilometres. I1i2 m. 179-2 km. 113-9 m. 182-2 km. II5 m. 184 km. 193 Between this point and Laggan one has the best view of the valley of Ten Peaks, also Paradise valley and the majestic peaks of the Bow range. The peaks which stand out in prominence are a few of the Ten Peaks, including Mt. Fay and Mt. Deltaform (11,225 ft.—3,421 m.); also Mt. Temple (11,626 ft. 3,544 m.), the highest peak in the range visible from the railway. On approaching Laggan, Fairview, Aberdeen, Whyte, and Vic. toria become visible. The first and lowest exposure of Pre-Cambrian occurs to the right of the railway. It is a coarse pebbly sandstone containing pink felspar. Laggan—Alt. 5,037 ft. (1,535 m.). From this point, type localities for Cambrian and Pre-Cambrian formations will be visited. A driveway and a railway lead up to Lake Louise and the Chalet. This lake is situated over 600 feet (183 m.) above Bow river, at the front of a large cirque which is occupied at the south end by Victoria and Lefroy glaciers. The lake is surrounded by Lower Cambrian quartzites of which the St. Piran formation stands out in prominence and forms precipitous cliffs. The contact between the Lower Cam- brian quartzites and the Middle Cambrian limestones is well shown in the lofty mountains about this valley. The illustration on page 178 shows the Mitre with Mt. Lefroy on the right, Mt. Aberdeen on the left, and a portion of the Lefroy glacier with a_ well defined bergschrund. The cliffs are Lower Cambrian, and the Mitre is capped with the Cathedral limestone of the Middle Cambrian. The pass to the right is called the Death Trap on account of its dangerous position. A visit will be made to Valley of the Ten Peaks, and the mouth of Paradise valley will be passed on the way. Both are typically hanging glacial valleys with glaciers at their upper termini. In the former the valley is Miles and Kilometres. 116 m. 185-6 km. 121-5 m. 194°4 km. 122 m. 195-2 km. 194 surrounded by ten gigantic peaks each of which shows the Lower and Middle Cambrian formations. Moraine lake lies in this basin between a large moraine and the Wenchemna glacier. Mt. Temple (11,626 feet), (3,543-6 m.), the highest in this part of the Rocky mountains, stands between these two valleys. The talus slope shown in the illustration on page 175 shows the position of the contact between the Pre-Cambrian and the Cambrian. The Middle Cambrian begins at the change in slope in the cliffs on the left, and the peak is capped by Upper Cambrian thin-bedded limestones of the Bosworth formation. Leaving Laggan station, a good exposure of Pre-Cambrian slates and shales wiil be visited within 200 yards (183 m.) of the west end of the railway yards. The illustration on page 173 shows the conformable contact between the Pre-Cambrian shales of the Hector formation and the Lower Cambrian quartzites. This contact is exposed in the south end of the ridge separating the Bow valley from the much smaller valley of Bath creek. One mile west of Laggan the railway leaves the Bow river and follows up Bath creek to the summit. Bow river continues toward the northwest, to its source in Bow lakes, 20 miles (32-2 km.) up the valley. The stream is enlarged by water from Hector lake. Mt. Hector (11,125 feet) (3,391 m.), with its castellated cliffs of Lower and Middle Cambrian formations, can be seen from the railway to the right of Bow valley. In a quarry on the right of the railway there is a good exposure of Pre-Cambrian slates, in fresh condition. These shales and slates are transported to Exshaw, where they are used in the manufacture of cement. The purplish and drab color of these rocks is char- acteristic of the formation. Looking ahead to the right can be seen the perpendicular cliffs of Mt. Daly formed in Middle Cambrian limestones, with a typical Miles and Kilometres. 122 2 1m 195-5 km. 125 m. 200 km. 128 m. 204:8 km. 195 cliff glacier, a fragment of the large Daly glacier, on its eastern flank. A few yards west of the crossing of Bath creek there is a good exposure of Cambrian basal conglomerate. It encloses fragments of the underlying slate, but the exact contact with the Pre-Cambrian is not visible along the railway. Kicking Horse Pass (The Great Divide)— Alt. 5329 ft. (14,625 mj:2= This is the con- tinental divide. The pass, discovered by Sir James Hector in 1876, is a_saddle-like depression about two miles broad carved out by the ice. The grade from the pass to the west into Kicking Horse valley is very much steeper than it is to the east into the Bow valley. To the right of the pass is Mt. Bosworth in which there is exposed nearly 9000 feet (2743 m.) of Lower, Middle, and Upper Cam- brian strata. The Bosworth section was exam- ined by Walcott (5) in 1908, this being the first attempt to subdivide the Cambrian of the Canadian Rocky mountains into form- ations. From this point it will be seen that the structure in the western slope of the Rocky mountains represents the western limb of a monocline; whereas the Cambrian basal con- glomerate is exposed near the divide, the rocks are Ordovician and Silurian in age in the last range to the west. Hector—Alt. 5,207 ft. (1,587 m.). The stream entering the lake at this point is Cataract brook. It drains Lake O’Hara and Lake McArthur, and glaciers on Mts. Victoria, Huber, Hungabee, Odaray, Cathedral and Stephen. Wapta lake at the right of the railway is the main gathering basin for the headwaters of Kicking Horse river. Below the end of the lake the river has cut a canyon through the Middle and part of the Lower Cambrian formations. From this point there is an excellent view of Yoho valley, a glacial U-shaped depression, which heads in the Yoho glacier. The valley Miles and Kilometres. 12 Op: 206-4 km. 130 Jem. 209-7 km. 132-5 m. 211-2 km. 196 is cut through Lower and Middle Cambrian strata. At Takakkaw falls, 1,248 feet (380 m.) high, the water cascades over Middle Cambrian limestone. The same formation causes the Twin falls, farther north in the valley, but the fall is not as great. Upper end of No. 1 Tunnel. Between the Pass and Lower end of No. 2 tunnel. Field, a dis- tanceof about eight miles (12:9 km.), there is a difference in elevation of 1,160 feet (353-5 m.), of which goo feet (274 m.) occurs within four miles (6-4 km.). To overcome this steep grade the Canadian Pacific railway has constructed two spiral tunnels. The upper one (No. 1), 3,200 feet (982-4 m.) long, is in Lower Cambrian quartzites in the base of Cathedral mountain. The lower one (No. 2), 2,900 feet (884 m.) long, is in Middle Cambrian limestones in the base of Mt. Ogden. There is a difference of 60 feet (18-3 m.) between the rails at the ends of the tunnel, in both No. 1 and No. 2. The average grade is now 2-2 per cent, whereas the grade of the old road, now used as a wagon road, is 4-4 per cent. Before entering No. 2 tunnel, the glacier- shaped Kicking horse valley is seen, with its broad aggraded valley floor. On the left of the valley is Mt. Stephen (10,485 ft.— 3,196 :m.), and: on ‘the right is- Mt) hield (8,645 f{t.—2,636 m.). About one mile (1-6 km.) west of Cathedral station the railway passes through a short tunnel in Lower Cambrian quartzites. Be- tween this tunnel and the wagon road there is a normal fault with about 3,000 feet (921 m.) displacement. Mt. Stephen is on the down- throw side, so that the Lower Cambrian quartzites in the Cathedral mountain come against the Eldon formation, at the top of the Middle Cambrian, in Mt. Stephen. This break has been called the Stephen-Cathedral fault. Miles and Kilometres. 137 m. 219-4 km. 197 From this point there is an excellent view of Mt. Stephen. The base of this mountain is Lower Cambrian and it is capped by Bosworth formation (Upper Cambrian). The Cathedral formation extends to the top of the great North shoulder. The Monarch mine is situated in Mt. Stephen about 1,000 feet (305 m.) above the railway in the Cathedral formation. The ore, con- sisting of lead and zinc sulphides, is a replace- ment deposit along a major and several minor - fissures. A concentrating mill, on the left of the railway, has been recently constructed and is separating about 80 tons of ore per day. The second short tunnel passes through the St. Piran quartzite in the shoulder of Mt. Stephen. The railway follows along the slope of the mountain, gradually approaching the level of the valley floor. At Field it is only 10 feet (3 m.) above the river. Field—Alt. 4,064 ft. (1,239 m.). This railway divisional point is the gateway to Yoho valley, Emerald lake and Ice River valley. The famous trilobite fossil bed outcrops in the Ogygopsis shale about 2,600 feet (793 m.) above the railway on Mt. Stephen. Walcott [6] has determined 32 species of trilobita and brachiopoda from this lentile of shale. This shale belongs to the Stephen formation (Middle Cambrian.). Another fossil bed recently discovered by Walcott occurs in the west slope of Mt. Field, in the ‘Burgess shale,’ which also belongs to the Stephen formation. This fossil bed is reached by Burgess pass and is shown in an illustration on page 177. From this shale Walcott [7] has determined trilobita, brachi- opoda, merostomata, malacostraca, annelids, holothurians and medusae. West of Field the beds dip more steeply to the west. A normal fault with the down- throw on the west side, passes between Mt. 198 Stephen and Mt. Dennis. This is called the Stephen-Dennis fault. Two miles (3-2 km.) west of Field the Kicking Horse river becomes a narrow channel and in one place passes under a natural bridge - formed in the Upper Cambrian shales and slates. Emerald—Alt. 3,895 ft. (1,188 m.). There km. are over 300 feet (91-5 m.) of Pleistocene from Field.lacustrine gravels along the sides of the Kicking Horse valley. The Canadian Pacific Railway Company has erected a gravel-washing plant at the station, the gravel being used for ballast after the clayey material has been washed out. On the north side of the valley five distinct terraces can be recognized in these gravels along the valleys of Emerald creek and the Amiskwa river. For the next four miles (6-4 km.) Kicking Horse river has a broad alluvial flood plain, nearly two miles wide in places. Looking ahead to the right of the railway red-capped peaks and ridges in the Van Horne range are seen. These red-weathering shales, slates, metargillites and phyllites belong to the Chancellor formation of the Upper Cambrian, and overlie those beds exposed on the top of Mt. Bosworth at the divide. On the south side of the railway in the Otter- tail range, these shales and slates are overlain by the massive Ottertail limestone which forms precipitous slopes. The accompanying figure shows a gentle slope on the Chancellor shales and avery steep slope in the Ottertail limestone. Some of the peaks in this range are capped by Goodsir shale, the lowest formation in the Ordovician. The very sharp contact exposed in Mt. Goodsir in the Ice River valley, between the Cambrian, represented by the Ottertail limestone and the Ordovician repre- sented by the Goodsir shales, is shown in another illustration page 180 (8). The fauna in those Miles and Kilometres. 199 shales determine the age of the beds. Mt. Good- sir (11,676 ft.; 3,565 m.) is the highest in the Rocky mountains near the railway.