Open Collections

UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

The cretaceous of southwest British Columbia with special reference to the Pasayten series in the east… Ney, Charles S. 1942

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata


831-UBC_1942_A7 N3 C7.pdf [ 28.73MB ]
JSON: 831-1.0302667.json
JSON-LD: 831-1.0302667-ld.json
RDF/XML (Pretty): 831-1.0302667-rdf.xml
RDF/JSON: 831-1.0302667-rdf.json
Turtle: 831-1.0302667-turtle.txt
N-Triples: 831-1.0302667-rdf-ntriples.txt
Original Record: 831-1.0302667-source.json
Full Text

Full Text

1 . THE CRETACEOUS OE SOUTHWEST BRITISH COLUMBIA With Special Reference To /•:••'..•" THE PASAYTEN SERIES. In the East-half of the Hope Area Thesis Submitted i n P a r t i a l Fulfillment of the Requirements for the Degree of MASTER OF APPLIED SCIENCE at The University of B r i t i s h Columbia A p r i l 21, 1942. Charles S. •Ney CONTENTS INTRODUCTION. • 1 Acknowledgements. . 1 THE DEFINITION OF THE CRETACEOUS. . . 3 Basis of Definition and Correlation 3 Absolute Age and Duration . * 4 CRETACEOUS EVENTS THROUGHOUT THE WORLD 6 Europe.,».»««••••«•»••••••••••»••••»•••••»••••••••••. China « . 6 Australia*» . . . • • » • • . » • • . . • . • • • » • « • * • • • • • • • • * • • « • • • » • » • • 7 India* . . . . . « » » * . . . » . » . . . . « » » » » » » » . . . « « . » * . . « . . » . » . . . » 7 South A f r i c a , . . . .. • • . . . . . . . . . • • « . . . . . . 8 CRETACEOUS OF NORTH AMERICA. . . . ' . * . . . . . . 9 C a l i f o r n i a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . * . . . *9 Alaska. . . . • * • • . . » • * • . . . . . . . o . . . . . . . • . « . • • « • • • « * » • » * » • 1 0 Great Plains...... • . . . . . . . . 1 0 TABLE OF CRETACEOUS IN SOUTHWEST B.C. 1 2 THE DEWDNEY-PASAYIEN SUCCESSION . . . 1 3 General.-... • » . . • • •••"13 D i s t r i b u t i o n . . . . . . . . . . . . . . . . . « • • • • « • • • • • • • « • • • . . . . . . 1 4 General Stratigraphy. . 1 5 The Ladner S e r i e s * . . . » . * * « » • . . . * . < . . . . . . « . • « . . « « . . « • 1*7 D i s t r i b u t i o n . . . , . . * . . . . . . . * . . . . . . . . . . 1 7 Lithology * • . . « * • • • • « • • • « « . « . . « « . « . . » » . . . . . . . . . . > 1 7 The Serpentine Belt••.••••••••.*.•••••••. » » 1 8 Origin of the Ladner Series*.»......<> 1 8 Age and Correlation. . . . . . . . . . . . 1 8 The Dewdney Creek Series.......... . 1 9 D i s t r i b u t i o n . . • 1 9 L i t h o l o g y . . . . . . . . . . . . . . . i . • • • . . « • . • * . . . • • • 1 9 Origin. 1 9 Age and Correlation.......... . . 1 9 The Dewdney Series. . . . . , . . . . . . . . » . . ; . . . . 2 0 D i s t r i b u t i o n . 2 0 Lithology West of A l l i s o n Pass 2 0 Specimen 2 7 . . . . . . . . . . . 2 0 Specimen 26 . . . 2 0 Specimen 2 5 . . . . . . • * . « . . . . • • • • • • . . , . . , 2 1 Lithology along the Skyline T r a i l 2 2 The Hampton Greek Formation. 2 2 D i s t r i b u t i o n . . . . . . 2 2 L i t h o l o g y * . . . . . . . « • • . . . • . . . . • • • . , . . « . * . » » . . < « • • • 2 3 Specimen 2 3 . . . . . . . 2 3 A l l i s o n ' Format±oii». * . * i . » 2 4 Lithology. 2 5 Frosty Formation 26 Lithology 2 6 6ontents-oont t d. ,;l Pasayten Volcanic Member.... .27 % General Remarks and Distribution. . 27 j L i*b32 o l o£>-y*•••• • • * * « • * • * • « • • « « • • « • • • « « « « ««*«•«e«»28 I Specimen 1 .28 j Specimen 4 29 1 * Origin. . 29 The Roche River Formation » 29 General Remarks and Distribution. .29 Lithology (Similkameen Section) 30 The Lower Section.. 31 Specimen 7 31 Middle A r g i l l i t e Section ..32 Upper Sandstone... .32 Specimens * 32 Specimen 11 • 33 Lithology"on Three Brothers Mountain.... .33 Specimen 12 ••,•.••.•••••.•••<<••«.....«33 Lithology -North of Skaist River 34 Specimen 14 34 Lithology i n Coquihalla Area ..35 Chuwanten Formation 36 General Remarks and Dist r i b u t i o n 36 .Lithology.•.....».<.«»»...«•«<<••<«•«.«•••••»...36 Specimen 17 37 Specimen 19 37 Structure i n the Dewdney-Pasayten. ...37 Structure i n Coquihalla Area.. 37 Structure along Skaist Valley. 39 Structure i n the Similkameen Area.. .40 Deformation of the Dewdney 40 Attitudes i n the Pasayten,............. 41 Faulting, . .41 Relations to the Hozameen Series................43 Relations to lag l e Granodiorite.................43 Relations to Younger Intnfsives. 45 Origin of the Structure. 44 Time of Deformation. .44 Structure Section. .... .45 Conditions of Deposition ~.... 46 LOWER CRETACEOUS WEST OF THE DEWDNEY-PASAYTEN AREA $0 Conglomerate on the Fraser River near 'Hope ....50 'The Tamihy Series, •..*.... 51 Cretaceous Rocks at Harrison Lake....... 52 Possible Cretaceous Rocks North of Vancouver. 53 Lower Cretaceous on Vancouver Island.., 54 General Remarks and Di s t r i b u t i o n , 54 Lithology. 54 Structure 54 Age, .55 Origin * 55 Contents-cont'd CRETACEOUS ROCKS EAST OE THE MAIN BELT ..56 The Spence's Bridge Volcanios .....•••«•• ..56 General Remarks and Distribution 56 Lithology 56 Specimen 28 57 Structure .... 58 Origin 58 Age • • 59 The So-called Cretaceous Rocks at Ashcroft ..59 Lithology 60 Structure • » 61 Cretaceous Rocks i n the East Half of the Ashcroft Area 61 Lithology 62 Structure 63 Age and Correlation 64 CONTINUATION OF THE DEWDNEY-PASAYTEN NORTHWEST 65 Eraser River Series .... 65 Dist r i b u t i o n .... .65 Lithology •.•.••*•••«•»•»••»•«»•••«•»..•••.••••66 Structure .66 The Eldorado Series 67 General 67 Dist r i b u t i o n ... 67 Lithology ..«..«..••••••.••»••«««•«•«••«•»•»«••«•68 Structure ............ ...........................69 Conditions of Deposition 70 Age . .....70 Representatives of the Eldorado NW of Chilko L. .....71 General 71 Dist r i b u t i o n 71 Lithology 71 Structure 72 Age 4 72 Upper Cretaceous Volcanics of Gun Greek Area ........ 72 D i s t r i b u t i o n . . . .,..72 Lithology ....................•...•.•«.••«•......72 Structure * * 73 Age 73 CRETACEOUS OF THE NORTHERN AREAS .73 The Hazelton Series . 73 Skeena Formation 74 Dis t r i b u t i o n ...75 Structural Relations 75 Upper Cretaceous of Owen Lake Area ., .76 Upper Cretaceous or Younger i n Fort Fraser Area .....77 CRETACEOUS ROCKS OF THE QUEEN CHARLOTTE ISLANDS ..........«7S R omojclc s • • • •« • • ••»»*••*• • •»• o«* »* • *»• # •«* * © » 9 3 Stratigraphy 79 Haida Formation .79 Honna Formation Contents-confd. Skidegate Formation .80 Structure .... 80 Time of Folding « 81 Conditions of Deposition .82 Age and Correlation .82 NANAIMO SERIES 85 General 83 Distr i b u t i o n ••....».«• ••••...>..... .85 Stratigraphy .84 Table of Formations ......85 General Lithology • .86 Descriptions of Formations 87 Benson • ..,,87 Haslam .•..,««»..,«.•.»»»>«,»«..«•..*«.....••.88 East Wellington .88 Wellington Coal Seam ,....,..,........< .,88 Extension 88 Cranberry and Newcastle .89 Protection • .89 Cedar D i s t r i c t 90 De Couroey 90 Northumberland 91 Gabriola .91 Structural Relations 91 Internal Structure ..............................91 Relations to Older Formations , 93 Relations to Younger Formations .............. 94 Conditions of Deposition ., .94 Age and Correlation 95 Time of Deformation 96 SUMMARY ...96 BIBLIOGRAPHY 101 APPENDIX: 1. Photographs of thin-sections. 2. General map of Cretaceous formations i n B.C. 5. Map no. 2. Dewdney-Pasayten Area. 4, Map no. 3. Nanaimo Series. TEE CRETACEOUS OF SOUTHWEST BRITISH COLUMBIA With Special Reference to THE PASAYTEN SERIES i n the East-half of the Hope Area. INTRODUCTION The *objeGt of th i s paper i s to bring together the available data concerning the sedimentation, volcanism, igneous intrusion and orogeny which took place during the Cretaceous period i n Southwest B r i t i s h Columbia. The data i s interpreted with the object of recording conditions, events, and processes of the period. A comparison i s made with the Cretaceous of the world i n general. Emphasis i s placed on the east-half of the Hope area. This d i s t r i c t provides a cross section of one of the more important Cretaceous series of the province. The author spent a few weeks working i n t h i s series during the summer of 1941 with H.M.A. Rice of the Geological Survey of Canada, A petrographic study was made of a number of specimens from the Hope area, and a few from the adjoining Ashcroft area. Acknowledgements Only a small part of t h i s work can be considered o r i g i n a l . Most of the data recorded has been obtained i n publications of the Geological Survey of Canada. These and numerous other sources are l i s t e d i n the bibliography, and are referred to by number from time to time. Special thanks are due Dr, H.M.A.Rice for allowing the author to use data obtained i n the Geological Survey work, much of which i s his own, and for providing many of the specimens for petrographic examination, and for general advice and ideas on the subjeot. For the t h i n sections and f i e l d (2) data on the rocks of the Ashcroft area, I am Indebted to Dr. W.E. Cockfield, Geological Survey of Canada, and his assistant, W.H. Mathews. I also extend my thanks to the professors of the University of B r i t i s h Columbia, for t r a i n i n g , advice, and information i n the work. (3) THE DEFINITION OF THE CRETACEOUS Basis of D e f i n i t i o n and Correlation The Cretaceous period was defined and subdivided i n Europe. Both the lower and upper boundaries as well as the subdivisions were essentially paleontological. In the o r i g i n a l l o c a l i t i e s these boundaries coincide with pauses i n sedimentation, or d i s -conformity, but there i s no basis for assuming that the same coincidence w i l l be found i n other areas. Since American geologists have judiciously elected to correlate with, the European standards, the correlation must be . on a s t r i c t l y paleontological basis (Osborn, 75). I t i s evident that even within America, correlation on the basis of diastrophism i s almost impossible. Correlation with European diastrophism i s almost f u t i l e . The problem i s one of correlating the diastrophio a c t i v i t y i n various areas with the European scale of organic evolution. The problem i s not simple. The upper l i m i t of the Cretaceous has been p a r t i c u l a r l y troublesome. In the f i r s t place the European scale was extended from the o r i g i n a l d e f i n i t i o n , so that new formations i n America had to be added to the existing Cretaceous, upsetting apparent relations with diastrophism. In the second place the Paleontologists were not i n agreement. Thus, i n America, Knowlton (54), from paleonotanical evidence, would put the d i v i s i o n much lower than Stanton (89) on invertebrate evidence, and others from vertebrate evidence. Much of the d i f f i c u l t y has been due to the geological complexity of the formations flanking the Co r d i l l e r a . Marine invasions i n any one area are very e r r a t i c . Continental deposits alternate with marine. Unconformities are d i f f i c u l t to f i n d , and (4) they may be l o c a l , and d i f f i c u l t to evaluate. Absolute Age and Duration The problem of the absolute age and duration of the Cretaceous or any other formation i s s t i l l f a r from adequate solution,. There are only f i v e r e l i a b l e Uranium/lead ra t i o s which are chronologically sandwiched between dated f o s s i l i f e r o u s strata (85), These are the tie-points to which the geologic time-table i s f i t t e d . None of these f a l l s i n the Mesozoic. One marks the supposed Laramide Revolution, and f a i r l y accurately dates the end of the Cretaceous, Ages based on the Helium/Uranium r a t i o (45) can be obtained for ordinary igneous rocks. At present the determinations show the same general progression, but f a l l short of the lead values. I f and when the method becomes accurate, i t w i l l prove an i n -valuable aid to Mesozoic dating i n the west where lavas and f o s s i l i f e r o u s strata are intercalated. By interpolating between the f i v e tie-points on the basis of the r e l a t i v e amounts of sedimentation i n the separate periods, i t i s possible to obtain f a i r l y close estimates of t h e i r durations. The following table summarizes the results of various investigators. The f i r s t column gives the r e l i a b l e r a d i o a c t i v i t y determinations, Geological and other data r e l a t i n g to them are given i n chapters 5, 6, and 7 of ref. 85. The second column gives minimum values obtained by B a r r e l ! (3), by interpolating between the tie-points on the basis of r e l a t i v e thicknesses of strata deposited. The t h i r d column gives values worked out by H.P.Woodward (85)(ch. 14). These values were obtained by calculating past rates of erosion and deposition, then considering the thicknesses of strata found. ( 5 ) They do not involve the tie-points, so the agreement with B a r r e l l T s values i s satisfying. The fourth column gives Schu-chert's values^ obtained i n essentially the same way as Barren's with a l i t t l e more refinement. The l a s t column Is a mean of Woodward1a ;and Barrell's values. The unit i s a m i l l i o n years. I t w i l l be seen that the Gretaoeous lasted from 120-130 u n t i l 60 m i l l i o n years ago, having a duration of 60-70 m i l l i o n years, or s l i g h t l y more than the Cenozoic. The ten divisions of the European standard w i l l be equivalent on the average to about 6 m i l l i o n years each. . * . : ' 1 : 2 3 4 . 5 Top of Cambrian . 450 Close of Ordovician 380 Mid-Devonian ...290 Early Permian ; 207 Total Paleozoic 360 471 360 435 Tr i a s s i c , 35 45 : 26 '43. , Jurassic 35 41 30 40 Lower Cretaceous Upper Cretaceous 25 (65) 40 70^ .....J-'211-(61) 40 73 Total Mesozoic 135 156 117 156 Early Cenozoic 60 Early Oligocene (Helium) 31 Total Cen. and Rec. 55 60 6 0 60 ( 6 ) CRETACEOUS EVENTS THROUGHOUT THE WORLD Throughout the world generally the Cretaceous history was f u l l of variety. Two outstanding characteristics are the wide-spread marine transgression, probably the greatest of a l l time, and a progressive coarsening of deposits with a return to fresh water environment toward the end of the period. This was a con-sequence of erra t i c and protracted diastrophism during the period as well as at the end. The L&?amide revolution cannot be regarded as a sharply-defined world-wide diastrophic event dos i n g the Cretaceous. Europe There i s no generally marked break between Jurassic and Cretaceous, though the l a t t e r begins with a fresh advance of the sea i n many areas. Epeiric seas advanced i n Neocamian and again i n Genomanian, reaching a maximum i n Turonian when a l l of north-west Europe was covered and the northern and southern oceans were connected. Most strata were t h i n marine beds, but i n the northern Alps, great thicknesses of coarse sediments (Elysch) were deposited. The close of the period was marked by an incomplete with-drawal of the sea, and mild u p l i f t i n certain areas. Some areas show a-complete t r a n s i t i o n to Tertiary deposits (Belgium), others show a great time break but l i t t l e unconformity (England). China The known Cretaceous deposits were en t i r e l y continental, and were i n a number of separated i n t e r i o r basins. Eresh-water beds with famous r e p t i l e remains l i e on folded and eroded Jurassic strata i n Mongolia. As much as 1 0 , 0 0 0 f t . of fresh water strata are found i n western Chansi and northern Shensi provinces. In ( 7 ) Szeehwan, deposits are conformable with the Jurassic. "Volcanic strata are interbedded with the sediments i n Shantung and along the southeast coast of China. Orogeny i s recorded near the beginning and near the end of the Cretaoeous. The e a r l i e r was accompanied by voleanism. The lat e r was accompanied by widespread intrusion and ore-formation along the southeast and south coast. This also folded the Cretaceous deposits, and may i n a general way correspond to the North American Laramide. Aust r a l i a In Australia .sedimentation was more' or less continuous from the Jurassic to the Cretaceous, The early Mesozoic strata i n the Interior were fresh water. The Cretaceous brought a widespread marine invasion i n which several thousand feet of marine el a s t i c s were deposited, i n the i n t e r i o r , and along the west coast. The period closed with u p l i f t and a t i l t i n g southward, following which the Continent has been emergent up to the present. The i n t e r i o r Cretaceous i s almost unfolded. That on the west coast has been downfaulted to the west, India In India the Cretaceous record i s f a i r l y complete. In the Himalayas sedimentation continued from the Jurassic without unconformity, though thicknesses are small and lowest Cretaceous beds have only l o c a l extent. Coarsening and thickening of de-posits i n Upper Cretaceous indicate r i s i n g of adjacent lands. Tethys was beginning to shallow, though some of i t s basins per-sisted well on i n the Tertiary, On the Peninsula, an extensive Cenomanian marine trans-gression i s recorded i n the Narbada y a l l e y , north of Bombay, and (8) on the Coromandel coast, south of Madras. In the f i r s t l o c a l i t y the fauna i s European, showing the connection of Tethys with European seas. In the second l o c a l i t y the fauna i s different and i s related to Assam and A f r i c a . The separation of Tethys and the Southern Ocean "by the hypothetical Gondwanaland i s thus strongly indicated. The f i n a l Cretaceous event on the Peninsula was the outpour-ing of the Deccan lavas, possibly associated with the breakup of Gondwanaland. Extensive intrusion of plutonio bodies has been correlated with t h i s event, but much of i t may be of l a t e r Tertiary age. There i s i n general no stratigraphic break between the Cretaceous and the Eocene i n India, though the beginning of up-l i f t of some parts of the Himalayas, and steady withdrawal of the seas i s indicated from the middle of Upper Cretaceous on. South A f r i c a Scattered marine strata range i n age from Wealden to Danian, and are strongly unconformable on the Karroo (Permian to early Jurassic). There i s no continuous succession anywhere. The deposits are t h i n and are small i n area, except for a large area under most of Portuguese East A f r i c a . Their present near-coast disposition makes a widespread marine transgression seem im-probable. Folding and fracturing took place i n mid-Cretaceous, c h i e f l y along the coasts. I t followed Permian trends i n Cape Province, l o c a l i z i n g the Uitenhage (Cretaceous) series into narrow s t r i p s . The coastal f a u l t i n g i s thought to be associated with the break-up of Gondwanaland, (9) The. Kimberlite pipes and minor alkaline lavas are thought ' to be post-Middle Cretaceous. Tertiary strata are both conformable and disconformable on the Cretaceous. There i s no evidence of a Laramide Revolution. THE CRETACEOUS Off NORTH AMERICA The Cretaceous period i n North America was featured by extensive marine transgression, deposition of great thicknesses of sediment i n narrow basins, and widespread voleanism. California: In Ca l i f o r n i a (32, 2, 92) a great thickness of marine sediments accumulated i n a narrow basin east of the present Coast Range. Following the Nevadan orogeny, i n which the early Upper Jurassic (Mariposa) sediments were folded and intruded and metemorphosed i n a very short time, deposition of the Fransciscan-Knoxville succession began immediately. This succession i s mainly shale, with cherts and basalts near the base, and attains a thickness of over 20,000 f t . These sediments were folded and eroded at the close of the Jurfissic - the Diablan "orogeny. The unconformity with the succeeding deposits proved or • d i f f i c u l t to recognize. I t may be s l i g h t absent i n some l o c a l i t i e s . Cretaceous deposition began immediately, closely following the Jurassic basin, and overlapping i t at several points, 12-18,000 f t , of shales with increasing amount of sandstone and conglomerate were thus deposited to form the Shasta Series. The age of t h i s series extends from lowest Cretaceous to Lower Albian, Overlying the Shasta unconformably Is the Chico Series. This (10) series i s ch i e f l y sandstone with much conglomerate, and i s of late Upper Cretaceous age. I t overlaps the older deposits, extending into Oregon and Washington, and i s i n broken contin-uation with the Upper Cretaceous of the Coastal Trough i n B. C. I t i s overlain by Tertiary strata (Tejon) with strong hiatus and unconformity i n Oregon. Alaska: Cretaceous rocks have wide d i s t r i b u t i o n i n Alaska. Martin (64) notes that the Lower Cretaceous seas were not limited i n extent by existing geographic features, and covered nearly the whole Territory. The Upper Cretaceous seas on the other hand were r e s t r i c t e d from the present mountain axes. The section on Alaska Peninsula shows 1000 f t . of marine shale (Stanuikovitch) overlying the Jurassic conformably. This i s followed by 800 f t . of limestone (Herendeen). Overlying these and the Jurassic formations with mild unconformity are shales and sandstones with coal constituting the Chigneck formation of Senonian age. Nearly 5000 f t , of Upper Cretaceous sediments are rep-resented i n the lower Yukon v a l l e y / The section begins with freshwater deposits of Dakota age. Most of the section i s marine, and i t ends with coal-bearing fresh water deposits. There i s thus a good p a r a l l e l with the Upper Cretaceous of the Great Plains. There i s not always clear evidence of unconformity with the Tertiary, but Martin concluded that there was u p l i f t and erosion at l e a s t , i f not fo l d i n g , i n a l l parts of Alaska. Great Plains: East of the Rocky Mountain belt the Cretaceous i s characterized by widespread marine deposition. E a r l i e s t (11) Gretaceous marine sediments are found i n Mexico, then somewhat l a t e r i n Texas (Glen Rose limestone), and the Gulf Coast, and lat e r i n Kansas and Colorado (Purgatoire shale). In the l a t t e r states the marine shales overlie the Morrison formation. This i s a fresh water and t e r r e s t r i a l deposit containing abundant rep-t i l e remains. I t i s variable i n thickness and age, and represents an i n t e r v a l of l i t t l e a c t i v i t y between the Jurassic and the Gretaceous seas. At the same time, thick, fresh and brackish water deposits with coal were being l a i d i n the Rocky Mountain region. These are the Kootenay and the Blairmore. The Blairmore extends into Upper Cretaceous, Late i n the Lower Cretaceous a sea extended from the Arc t i c to deposit the MacMurray Tar Sands and several other marine formations. In eastern United States (89) the Lower Cretaceous i s represented by the fresh water Potomac Series. •With the coming of Upper Cretaoeous the seas extended much farther. The A r c t i c and Southern seas joined. In some l o c a l i t i e s (Colorado, Montanaj and Dakota) an# i n t e r v a l of fresh water deposition represented by the Dakota sandstone, eame between Lower and Upper Cretaceous, This i s absent i n northern Alberta (70). In both cases a thick succession of marine shale and sand-stone formations followed. In Canada the two main shale members, Pakowki and Bearpaw, are separated by the Belly River sandstones. These are fresh water sediments representing an i n t e r v a l of con-t i n e n t a l deposition. Their thickness and time value increases westward toward the Rocky Mts, They are absent i n Colorado and Wyoming, and the combined shale formation (Pierre) i s 5000 f t . thick. ( 1 2 ) The overlying Fox H i l l s sandstone, and the formations following, show a coarsening of material. Alternating marine, fresh, and coal-hearing brackish water deposits record the os-c i l l a t o r y withdrawal of the seas. Bentonite beds are common through a l l of the Upper Cretaceous. They are the record of far away voleanic eruptions west of the Cordilleran geosyncline. The contaet with the Tertiary i s variable. (See 74 etc.) In some l o c a l i t i e s there i s a gradual t r a n s i t i o n into strata of Eocene age. In others there are various degrees of unconformity. I t i s apparent that, considered over any appreciable area, the Laramide was complicated. Even closely separated areas were affected at different times, and the l a t e r areas recorded, i n the coarsening of t h e i r deposits, the deformation that had struck the e a r l i e r areas. TABLE OF ORETAOEOUS FORMATIONS IH SOUTHWEST BRITISH COLUMBIA The table on the following page indicates the age r e l a t i o n s , compared to the European standard whenever possible, of the series' and formations to be described i n t h i s paper. The heavy black l i n e on the l e f t of the column shows the age extension. Where broken, the l i n e Indicates uncertainty. The blue l i n e on the right of the column represents marine conditions of deposition. TABEE OE CRETACEOUS FORMATIONS IN .SOUTHWEST B. 0. European Maest-r i e U i a n Cam-panian San-tonian Coni-aoian Turonian Cenomanian A l b i a n Aptian Barremian Haute r i v i a n Valaiiginian Similkameen Chuwanten Roohe River (/frtu/i Jrll. tsA.) /4/>aJ ' I l 1 ffrOSty (SS. zee" AlliSOIl C £e«g. ) - 260O' Hampton Cr, . C Breccia , ./off, &rir }• 7t>oo ' Dewdney Ser. ('•suits', /o,ooo Goquihalla HarfrisoTi T.ake Lower Grot. {frit. fh., fffrff).-Dev/dney Cr. (n/f^/qsoe . Ladner Ser, I ('-State ' +J*'k<ir<t4fij.y- inec • Brokenbaok H i l l peninsula, Bridge "River Upper Cret. V o l . Eldorado Ser. (ay, Sperioe'a'Bridge Vol'canios Ashcroft (*,3. JJ. * fit -)Jt>°° ' Northeast Area Fort Eraser (/Ind. rote / &»f. * j^e ) Owen Lake Skeena (St,, tof.,**^,* Hazelton Ser. Coastal Trough Nanaimo Ser. (Jh, (fty., art. Sl.~)iq40G' Queen Charlotte Ser. West Coast V.T. ..,.y I I (13) THE DEWDNEY-PASAYTEN SUCCESSION General A well-defined belt of closely associated Jurassic to Cretaceous rocks occupies the east flank of the Cascade Range i n southern B,, C. and adjacent Washington. The succession may i n -clude a disconformity or mild unconformity. The older rocks are largely of volcanic o r i g i n ; either direct pyroclastics or water-transported material of volcanic o r i g i n . The younger rocks are largely coarse impure sediments with minor shales, t u f f and flows. The e a r l i e r rocks are of a marine environment, the higher parts of the Cretaceous are t e r r e s t r i a l . These rocks were described i n Washington by Bauerman i n 1860 (6), Dawson described them along the Dewdney t r a i l i n 1877 (27), and gave them the name Similkameen Series, I , G, Russell (82), i n 1900, described the rocks i n Washington. Smith and Calkins (87 - 1906) made a more complete examination, adding to the series intthe west a group of slates"1" which Russell thought were much older. They named the whole succession the Pasayten 'formation', Daly (25), a few years l a t e r , obtained a good section along the 49th p a r a l l e l , and changed the name to Pasayten 'series'. Later work by Cairnes i n Coquihalla area (12, 14), along the Dewdney t r a i l (13), and i n the Skagit and Similkameen valleys (15), showed that the s l a t y rocks on the west were older than the coarse e l a s t i c s , and not younger, as Daly's section would indicate. The older rocks were called Ladner Series and -'-The term 'slate' i s used loosely to include b r i t t l e , f i s s i l e , fine-grained rocks. No extensive development of secondary sl a t y cleavage occurs anywhere i n the succession. (14) Dewdney Creek series, and the name Pasayten retained for the younger coarse e l a s t i c s . During 1941, H. M. A. Rice, to whom the writer was assis-tant, examined the belt i n considerable d e t a i l i n the area north of the 49th p a r a l l e l and east of the 121st. meridian. This area w i l l be spoken of as the Similkameen area from time to time. The results of th i s work i n part are embodied i n the present paper. • Distribu t i o n (See map no, 2) From the 49th p a r a l l e l between the Pasayten River and Lightning Creek, the Dewdney and Pasayten rocks form a wel l -defined belt extending i n a NNW dire c t i o n to Coquihalla v a l l e y , and extending southeast 20 - 30 miles into Washington. Probable correlatives are the Mesozoic rocks of the Fraser River and the Bridge River d i s t r i c t . The western boundary, against the Cache Creek rocks of Paleozoic age, i s irregular and shows a tendency to swing north-ward across the general s t r i k e of the formation. For a few miles north and south of the 49th p a r a l l e l i t i s a strong north-south f a u l t . The northern sections of the boundary, as i n the Coquihalla area, do not appear to be faulted. The-eastern boundary i s a f a i r l y straight l i n e trending N 35° W fo r nearly 40 miles from the 49th p a r a l l e l . Over t h i s entire length i t i s separated from the Triassic Hicola rocks by the dike-like Eagle batholith. The relations of t h i s body w i l l be considered l a t e r on. In Washington, the volcanic member considered by Daly to be basal to the Pasayten, i s mapped as Miocene, overlying both the Pasayten and the Remell batholith. The batholith truncating the (15) Pasayten rocks on the south i n Washington i s considered to he i n -trusive? into them. In the north along Coquihalla v a l l e y the rocks are cut off by younger intrusives and dislocated by f a u l t i n g along the l i n e of the valley. General Stratigraphy The following table gives a comparison of the succession i n Coquihalla area and i n Similkameen area. In the former area the suceession begins with the Lower Ladner formation, comprising some 8000- feet of slate with some graywacke and conglomerate. Locally i t i s overlain conformably by the Upper Ladner formation consist-ing of 1000 feet or more of s l a t e , g r i t , and conglomerate. Ap-parently conformable on the Lower Ladner, perhaps i n part equiva-lent to the Upper Ladner, i s the Dewdney Creek Series, consisting of about 10,000 feet of tuffaceous rocks. Overlying the Ladner with faulted relations and possible unconformity are the 'Lower Cretaceous' sediments. These are massive g r i t s , shales and con-glomerates t o t a l l i n g 8000 feet i n thickness. In the Similkameen area Dewdney and Ladner are not separated, though they doubtless both occur. The whole group of slates and t u f f s , at least 10,000 feet i n thickness i s referred to as the Dewdney Series. Above t h i s i n order are f i v e formations; 1 (l)the Hampton Greek, 7000 feet of breccia, t u f f and sediments, (2)the A l l i s o n conglomerate, 2000 feet of coarse conglomerate, (5)the Frosty formation, at least 2000 feet of feldspathic sandstone, (4)the Roche River formation, 16,000 feet of c h i e f l y massive g r i t , and (5)the Chuwanten formation, 2-3000 feet of purple a r g i l l i t e , t u f f and conglomeratic sandstone. The apparent stratigraphy i n the Similkameen area i s indicated -'-The formation names used here are provisional field-names only. (16) i n the t h i r d column. This w i l l he understood from the structure-. section on page 45. I t contains two f a u l t s ; (1)the L i t t l e Muddy f a u l t s between the Dewdney series and Frosty formation, and (2) the Chuwanten f a u l t between the Hampton Creek and the Ghuwanten formations. F o s s i l evidence indicates that the Roche River beds are younger than the Dewdney. I t i s evident then that the f a u l t s both have large stratigraphic displacement, and that the s t r a t i -graphy should be as i n column 2. • Since t he time break between the Roche River and the Hampton Creek i s greater than that between the Hampton Creek and the Dewdney, the Dewdney should perhaps be extended to i n -clude the Hampton Creek formation. The A l l i s o n conglomerate would then represent the actual break, apparently of l i t t l e im-portance, between the Dewdney and the Pasayten. The map retains the old subdivision to conform with Gairnes. 1 Goquihalla 2 Similkameen 3 Daly vi •A 6-r rr rChuwanten rDewdney 3 - Lower Gretaceous Roche River A l l i s o n •Frosty J; A l l i s o n Hampton Greek «' Chuwanten Frosty [Hampton Greek ^ Roche River Dewdney Cr, Ser. Dewdney Series IPasayten "Volcanic Ladner Slates In c o l . 2. A - Designation proposed by Rice, 1941 B - Designation of Cairnes, 1923. This i s retained i n present map and report. (17) The Ladner Series Distribution: The Lower Ladner forms the ."'sslate belt' crossing the Coquihalla v a l l e y between Po r t i a and Jessica stations i n a N 35° W direction. North of the Coquihalla i t i s only 2-J- miles wide, bounded on the.west by the Paleozoic rocks and on the east by younger intrusives. South of the Coquihalla i t widens both east and west to about s i x miles, and on the east i s i n faulted contact with the Lower Cretaceous rocks. In the middle of th i s southern area around the headwaters of Dewdney Creek, and separat-ed from the Cretaceous rocks on the east by a narrow s t r i p of sl a t e , i s the Dewdney Creek Series. A wider band of slate leaves Coquihalla map-area west of the Dewdney area, but Cairnes does not map Dewdney and Ladner separately along the Dewdney t r a i l a few miles to the south (13). The Upper Ladner covers only small areas, the largest of which i s a few square miles l y i n g between the forks of Ladner Creek. Lithology: The Lower Ladner i s c h i e f l y a dark green carbonaceous slate containing abundant pyrite and pyrrhotite. There i s a ten to f i f t y - f o o t band of conglomerate near the base. This i s com-posed of pebbles under 1 inch i n diameter of chert, quartz-porphyry and some plutonics i n a slaty matrix. Beds of greywacke occasionly occur up to 100 feet thick. They have a high proportion of feldspathic fragments i n a'fine s i l i c e o u s groundmass. There are also beds of black rocks with scattered fragments of fresh feldspar, quartz, and f e l s i t e i n an argillaceous groundmass. Total thickness of the Lower Ladner i s about* 8000 feet. The Upper Ladner contains a higher proportion of coarse beds. A conglomerate at the base contains abundant fragments of shale. (18) The g r i t s are characterizeddby an excess of fresh angular feldspar. The Serpentine Belt: Along the contact of the Ladner and the Paleozoics on the west, a belt about a mile wide, including mostly Paleozoic rocks, but some of the Ladner slates, i s i n -tensely affected by basic intrusives. The belt appears to die out i n the souths I t was not mapped along the Dewdney t r a i l , nor was i t encountered anywhere i n the Similkameen area. In-trusives of intermediate composition however were found to be very abundant a l l through the Dewdney Series i n the Similkameen area* Origin of the Ladner Series: On the basis of the freshness and angularity of the feldspar and the high feldspar/quartz r a t i o characterizing the g r i t beds i n the slates, and of the peculiar composition of the slates themselves (Na20/Kg0=l,6), Cairnes postulates a volcanic source for the material. Intercalated calcareous strata Indicate a marine environment of deposition. He favours the idea that recurring ash f a l l s on the adjacent lands providedcidebris,j which could be rapidly swept away and deposited without much decomposition* Age and Correlation: F o s s i l evidence, based on a single belemnite indicates Jurassic or Cretaceous age. The Ladner i s apparently continuous with a r g i l l i t e s near Boston Bar. These contain post-Triassic horizons, but are i n apparent conformity with the Cache Creek rocks. A laek of greater deformation i n the Cache Creek rocks than i n the Ladner strata suggests that no great uncon-formity exists between them. The succession may include only diasjyems. (19) The Dewdney Greek Series Distribution: The extent of the series i n the Coquihalla area has already been indicated i n the discussion of the Ladner. In i t s extension southeast i t has not been separated from the Ladner, so the following description w i l l apply only to the Goquihalla area. The sections i n Similkameen area w i l l be discussed sep-arately as the Dewdney series. Lithology: Ther are three l i t h o l o g i c divisions. The lower, about 4000 feet thick i s dominantly coarse, thick bedded, dark to gray-green c r y s t a l - l i t h i c and l i t h i c andesite t u f f . I t i s rapidly variable, and units are l e n t i c u l a r . Above this i s the intermediate c r y s t a l - l i t h i c t u f f , 5500 feet thick. This i s blue gray to black, thin-bedded, and composed of angular feldspar, quartz, and l i t h i c l a p i l l a e i n a fine ashy matrix. The upper d i v i s i o n of crystal t u f f i s mostly fine grain pyroclastics with some normal sediments. I t varies i n different l o c a l i t i e s . I t i s about 2500 feet thick, making a t o t a l of 10,000 feet for the whole series. Origin: The rocks are p a r t l y d i r e c t l y deposited pyroclastics, partly water-deposited volcanic materials with some true sediments. The angularity of the p a r t i c l e s and the l e n t i c u l a r i t y of the units indicate l o c a l i z e d and rapid accumulation. The true sedimentary beds are of fine material, indicating that the adjacent land was either distant of low-lying. The f o s s i l fauna indicates a marine environment. v Age and Correlation: In the lower zone belemnites are common, but nothing else. The intermediate zone carries a more varied fauna. The f o s s i l s indicated only Jurassic or Lower Cretaceous age. (20) / The Dewdney Series / Distribution: We are considering now a l l the strata l y i n g west of the L i t t l e Muddy Fault and bounded on the west by the Paleozoic rocks. The l a t t e r boundary i s irregular and i s made up of several f a u l t s i n the southern part. The section north of Shawatum Mtn. i s mapped as a low-dipping unconformity (Gams e l l , 16). The rocks are ¥/ell exposed along several east-west ri§ges extending west from the Skagit-Similkameen v a l l e y , though a complete section was not obtained during 1941. Lithology West of A l l i s o n Pass: On the ridge extending west from the Skagit v a l l e y at a point 2 miles north of A l l i s o n Pass, about 10,000 feet of mainly shales and t u f f s are exposed. The lowest beds are alternating coarse and fine t t f f f s . Specimen 27 i s t y p i c a l of the f i n e r t u f f s . They vary rapidly i n texture from s l a t y to sandy, showing good s t r a t i f i c a t i o n . They are l i g h t blue-gray, conspicuously pyritous, and hard s i l i c i f i e d . Less abundant are the coarser c r y s t a l - l i t h i c t u f f s , of which spec. 26 i s t y p i c a l . This consists of angular fragments of f e l s i t i c rooks mostly under 1 cm. diameter, along with scattered feldspar and quartz crystals i n a dark blue-gray matrix. The specimen shows-; about 35% of rock fragments, 30% feldspar fragments, and about 5% of quartz, the remainder being minute c r y s t a l fragments and unresolved material. The rocks are a l l fine-grained feldspathic types, low i n quartz, and devoid of dark minerals. Many are v i t -rophyric. The feldspar i n them i s a l k a l i . The fragmental f e l d -spars are fresh and angular, and mostly orthoclase, with smaller amount of ol&goclase. The rock type represented i s therefore trachyte. (21) Spec. 25, from the west peak of Snas.s Mtn, i s thought to be Dewdney (see p. 40). I t i s a c r y s t a l - l l t h i c pyroclastic, similar i n texture and appearance to spec. 26, but i s more basic i n composition. I t i s about half c r y s t a l s , and these are chi e f l y plagioclase, some of which i s as basic as labradorite. The rock fragments are mostly andesine vitrophyres. There i s a l i t t l e serpentine, pyroxene, limonite, c a l c i t e and s e r i c i t e . The t u f f s become f i n e r and pass into slaty rocks and to a d i s t i n c t i v e type of sandy shale. This shale has lines of len-t i c u l a r laminae of fine sandy material regularly spaced through i t . Exactly similar shales are noted along the Skyline t r a i l section. About 3000 feet below the top of the section there i s a band of moderately coarse conglomerate. The boulders are up to four inches, are well rounded and include plutonic types. The matrix Is an impure g r i t t y brown-colored sandstone. According to the interpretation of the structure as a syncline with i t s axis about 2 miles west of Skagit v a l l e y and trending a l i t t l e west of north, the conglomerate i s -repeated 1 and 3 miles west of the va l l e y . On the eastern limb the conglomerate i s at least 100 feet thick and i s much coarser and thicker than on the west-ern limb. Ther are numerous concordant s i l l - l i k e bodies of rock showing a range i n composition from dark hornblende porphyry to moderately coarse syenite. They increase i n number and thickness tov/ard the west, where they make up about half the section. The aggregate thickness i n f i v e miles of section must be about 6000 feet. The t o t a l thickness of the Dewdney represented here, allow-ing for the intrusives, must be over 10,000 feet of which only (22) the lower 4000 feet, and small sections above that are direct pyroelastics. Lithology along the Skyline t r a i l : Rocks of the Dewdney Series are w i l l exposed for 7 miles along the ridge north of Lightning Greek, known as the 'Skyline t r a i l ' . The structure was not worked out along here, and only a general description can be given. Most of the strata i n the eastern part of the ridge are dark colored thin-bedded, s l a t y shales, with minor sandy beds. Much of i t shows the characteristic small scale l e n t i c u l a r i n t e r -lamination of fin e sandy and dark shaly material noted i n the section west of A l l i s o n Pass. Further west, and probably lower • i n the section, massive beds of limey shale and sandstone appear, and carry a considerable marine invertebrate fauna. On the ex-treme west the shales have interbeds of t u f f and of hard gray-green graywacke, the g r a n i t i c arkose of the lower Roche River formation, and similar to the g r i t beds described by Gairnes i n the Lower Ladner Series. Hampton Creek Formation West of the Chuwanten f a u l t , and underlying the A l l i s o n con-glomerate (p. 24) i s a series of 5000 feet of volcanic t u f f and breccia, and i n some places flows, overlain by and I n t e B s t r a t i f l e d toward the top with shale and sandstone. The sandy shales near the top contain marine f o s s i l s . At one l o c a l i t y there i s conglomerate below the breccias. « Distribution: The formation i s well exposed on the h i l l just west of the junction of Castle Creek and Similkameen River. I t i s picked up again west o f the Chuwanten Creek, near the 49th. p a r a l l e l , (25) again a few miles east of A l l i s o n Pass, and f i n a l l y on the northeast peak of Snass Mtn. Here i t i s i n faulted contact with the g r i t s on the east. The west peak of Snass Mtn. i s composed of c r y s t a l - l i t h i c t u f f s l i t h o l o g i c a l l y similar to those of the Dewdney* I t i s therefore suggestive that the Hampton Creek formation i s faulted against the Dewdney at t h i s point Lithology: There i s wide .variation i n the lit h o l o g y i n different areas. Near the Similkameen, and to the south, the formation i s characterized "by massive thick beds of hard, dark-brown g r i t t y sandstone or t u f f of which Sp, 23 i s t y p i c a l . These are inters s t r a t i f i e d with dark a r g i l l i t e . Sp. 23 i s a l i t h i c t u f f con-s i s t i n g of p a r t i c l e s 2 to 5 mm. i n size, which are chi e f l y rock, with a few crystals of altered feldspar, a few of pyroxene, and a l i t t l e t i t a n i t e . The rocks are c h i e f l y feldspar v i t r o -phyres, of approximately trachyte composition. Most of the matrix, i.e. 50% of the rock, i s c a l c i t e i n large grains. I t does not appear to be replacing anything, and so i s quite l i k e l y of diagenetic o r i g i n . Leucoxene i s prominent around the grains. The rocks owe t h e i r dark color to f i n e l y distributed iron oxide. A few dark flows occur i n the lower part of the section. Above the volcanic portion of the formation there i s a section of 1000 to 2000 feet of g r i t s and interbedded sandstone, shale, and limey shale. These sediments contain marine f o s s i l s . Near the 49th p a r a l l e l and west of the Chuwanten, and again three miles north along s t r i k e , there are s i m i l a r trachyte-tuffs, (e.g., Sp. 21). They are considerably coarser than 23, but of the same makeup, and the matrix i s likewise coarse c a l c i t e . (24) A few miles east of A l l i s o n Pass the Hampton Greek for-mation consists mainly of a coarse, close-packed angular breccia of andesitic fragments over one foot i n size. Proceeding down-ward i n the section, the breccia becomes f i n e r , and interbeds of dark-brown tuffaceous sandstone appear, accompanied by shales. Slate and cherty fragments appear i n the fi n e r breccia. S t i l l lower i n the section there i s about 400 feet of conglomerate. I t i s of cobble size, composed of well-rounded and close-packed volcanics and a few granites, i n a matrix of dark-brown g r i t . Below the conglomerate again l i e more of the brown tuffaceous sandstones. A s i m i l a r , though c h l o r i t i z e d and more indurated, breccia of.andesite forma the northeast peak of Snass Mtn. A l l i s o n Formation The A l l i s o n i s a remarkable, coarse, thick and persistent conglomerate. I t has been mapped from three miles south of the 49th p a r a l l e l to three miles north of A l l i s o n Pass, a distance of 16 miles. I t probably extends at least another 15 miles into Washington, since a similar conglomerate i s mapped at the head of Canyon Creek north of Barron (87). The northern end has not been completely mapped. I t appears to be duplicated by f a u l t i n g 3 miles north of A l l i s o n Pass, The western limb may continue to the northwest, but Cairnes (13) does not mention i t i n the Skaist val l e y , so that i t may be again cut off by a f a u l t as suggested on the map. A small area of'what i s almost certainly the same conglomerate l i e s between the peaks of Snass Mountain north of Skaist v a l l e y . This appears to have been thrust from the south (25) onto the Hampton Greek voleanics. In Coquihalla area a very similar conglomerate occurs i n small areas i n the valley below Borneo. The heavy conglomerate In the Cretaceous of Jackass Mountain 40 miles to the northwest may well be the continuation of the same formationn Lithology: The conglomerate i s composed of well-rounded beulders from 1 inch to 2 feet i n diameter, f a i r l y close-packed i n a matrix of arkose. Though the maximum size range i s great, i t i s small i n amy one l o c a l i t y . The roundness of the large boulders i s often s t r i k i n g . A rough analysis of the conglomer-ate showed the following percentages of rocks,. Light-colored plutonics. 50 Feldspar porphyries 17 Slates 8 Grit 5 Chert 4 Quartz 1.4 Schist v 1.2 Gneiss 0.6 Matrix 34.0 This analysis cannot be considered representative of the whole conglomerate as the^re i s much/variation, In different . l o c a l i t i e s . This was made a few miles southeast of A l l i s o n Pass. " The matrix i s a very hard gr a n i t i c arkose, very similar to the Roche River.rock. I t shows f a i r l y uniform size and i s a l -ways distincttfrom the pebbles. Bedding planes are rare. In some sections of 1000 feet of conglomerate, no nore than half a dozen t h i n unpersistent bands of g r i t would be found, South of Three Brothers Mtn. two beds of shale up to f i f t y feet thick are found i n i i t . (36) The thickness has been measured i n several places, and averages 1500 feet. Rice, i n 1941, measured a thickness of 2100 feet northeast of the Upper Similkameen valley. Smith and Oalkins give 500 feet for the thickness of the conglomerate at the head of• Canyon Creek, and Cairnes gives the same figure for the conglomerate i n Goquihalla v a l l e y below Romeo. In the Similkameen area i t s attitude deviates l i t t l e from Ef55°W -<c 5Q-65°SW. I t i s apparently conformable with the older and younger formations. On the h i l l north of Castle Creek i t shows an abrupt contact with the shales, and a sl i g h t disconformity or cut and f i l l , can be observed. The extended parallelism with the underlying formations i n outcrop and i n attitude speaks for the absence of an appreciably unconformity. Frosty Formation The A l l i s o n i s overlain by a formation of massive arkose and shale. The area occupied by these strata i s about two miles at the 49th p a r a l l e l and taper^s off to the northwest beyond A l l i s o n Pass, being cut off against the Dewdney by the L i t t l e Muddy f a u l t , which crosses the A l l i s o n s t i l l further north, Lithology: The rocks are largely massive feldspathic sandstones. These are dark gray and brownish, and c h a r a c t e r i s t i c a l l y spotted with ?fhite weathered feldspar. They are similar i n composition to, but lack the texture and induration of the Roche River rocks* Interbedded with these are rapidly varying beds of sandy shale, and a r g i l l i t e with l e n t i c u l a r pods of limestone. Conglomerate (27) bands appear a few hjmdred feet aboye the A l l i s o n , and the contact i s gragational. Pasayten Volcanic Member General: There i s at present a considerable c o n f l i c t of ideas regarding t h i s formation. Daly (25 P. 481-482) described the base of the Pasayten Series near the Pasayten r i v e r at the 49th. p a r a l l e l . He found a basal member of volcanic agglomerate, some 1400' feet thick l y i n g unconformably on the deeply eroded surface of the Remmel batholith. No attitudes were obtainable i n t h i s agglomerate, but he ass^^med conformity with the apparently over-l y i n g Pasayten sandstone on the basis of the constant width and direction p a r a l l e l to the trend of the Pasayten strata. In 1941 thi s volcanic was seen a few miles to the north, thus extending Daly's narrow belt. I t appeared to be d e f i n i t e l y overlying the granite unconformably, but nothing of Its relations to the Pasayten could be determined. Smith and Calkins i n Washington mapped an elongated area of volcanic two to three miles wide i n places and narrowing down to-' vi?ard the 49th. p a r a l l e l to be coextensive with the volcanic as Daly mapped i t . They considered i t to be Miocene, and to overlie both the granite and the Pasayten unconformably. I t i s mapped i n this way on the Preliminary Geological Map of Washington, 1956. (24) Culver states that the assignment to the Miocene f i t t e d data further south, but i s not en t i r e l y satisfactory. 2 Division of Geology, Pullman, Washington, personal commun-ica t i o n . (28) The same volcanic was not found at any other place along the east contact of the Pasayten. The actual contact with the granite i s hidden south of Hope Pass, but the gaps between out-crops would only allow for a few hundred feet of volcanic at the most. - •, At Hope Pass, and for some distance north, and again north of Tulameen River, the base of the Pasayten contains a few bands of t u f f interbedded with feldspathic sediments. At Hope Pass the nature of the granite contact could not be d e f i n i t e l y determined, but north of the Tulameen River, the dips of the strata are low to the west, and unconformity with the granite i s evident (12), Lithology: Daly describes the Pasayten ^olcaniosas t y p i c a l andesite breccia, with fragments up to one foot i n diameter i n a well consolidated ash, very massive, u n s t r a t i f i e d , and of uni-form composition. The blocks are andesite with labradorite and pyroxene phenocrysts. One outcrop of vesicular andesite sug-gested the presence of a flow, / • The rocks seen by the writer a few miles north of the 49th. p a r a l l e l were mostly breccia of feldspar porphyry, with fragments usually under one inch i n diameter. At one place a very fresh plagioclase-augite porphyry (spec. 1) was found, which i s very l i k e l y a flow rock. I t 1 s freshness i s strongly suggestive of Tertiary age. A .few miles north of Hope Pass, there i s a bed of s t r a t i -f i e d t u f f about 150 feet thick, with smaller beds above and below interbedded with g r i t s . These t u f f s are bluish gray (spec. 2) (29) to very dark (spec. 4), The f i r s t i s hard and s i l i c e o u s , and i s composed c h i e f l y of fragments of feldspar and clear quartz, i n an aphanitic matrix. The second i s a i a t i t e c r y s t a l t u f f , fine-grained and dark i n hand specimen with only a few f e l d -spars v i s i b l e . Although interbedded with sediments i n t h i n bands, the t u f f s are unsorted. Under the microscope, recogniz-able c l a s t i c grains are 70%, matrix 30%, though there i s actually complete gradation of sizes. Of the grains, 40% are angular quartz, 50% feldspar, the rest mica. The matrix i s composed of c a l c i t e , s e r i c i t e , c h l o r i t e and carbon i n that order of abund-ance. The c a l c i t e replaces matrix and feldspars a l i k e . The feldspar i s ch i e f l y fresh orthoclase, but some i s andesine. Cairnes describes the volcanics on the Railroad-Kelly Greek divide simply as "purplish red volcanic breccia interbedded with grey feldspathic beds." Origin; The Yoleanics at the 49th p a r a l l e l represent a heavy explosive eruption from a nearby vent. The rocks are andesite. The volcanics near Hope Pass are ash accumulations from explosive .eruptions which may have taken place a hundred miles from the s i t e of deposition. The rocks represented are rhy o l i t e or l a t i t e . In the f i r s t case they may have been p i l e d on a land surface some time before sediments began to accumulate there. In the second case the ash f e l l d i r e c t l y into the basin i n which sediments were accumulating under water. The two formations have nothing i n common. The southern one may well be faulted-in Tertiary volcanics. The Roche River Formation General: This formation presents a monotonous succession of (30) moderately coarse, impure, c l a s t i c sediments with only a few minor beds of shale, attaining a t o t a l thickness of about 15,000 feet. I t s upper l i m i t i s a r b i t r a r i l y defined to be the purple tu f f s and sandstones of the Chuwanten formation. The belt i s thus about four miles wide from the 49th p a r a l l e l to the Skaist va l l e y , over which the strata form a single great homooline (see p. 45), I t s indurated character i s manifested i n the fo r -mation of the elevated tracts of Three Brothers Mountain and Chuwanten Mountain, each having steep anti-dip slopes on which are the f i r s t cirques west of the Interior Plateau, The formation could no doubt be traced many miles southeast into Washington. Several thousand feet of similar massive feldspathic sandstones are found near the head of Canyon Greek (87), In Coquihalla area, Cairnes* (14) section along the Cedar-Carey Greek divide, considered Lower Cretaceous, probably i n -cludes some of the Roche River formation. I t includes several thick beds of massive g r i t , but nothing comparable to the section along the Similkameen about to be described. i n 1941 an excellent section of the Roche River and Chu-wanten formations was obtained along the Similkameen v a l l e y , and the rocks were also studied at various l o c a l i t i e s on Chuwanten and Three Brothers Mtns. and on the ridges east of Snass Mtn, Lithology: The section along the Similkameen, aggregating 15,500 feet of strata was divided into a lower 10,000 feet of massive g r i t , an upper 3500 feet of sandstone, and between these a 2000 foot section i n which a r g i l l i t e bands alternate with the g r i t s . Throughout a l l three sections, but noticed p a r t i c u l a r l y i n the Middle A r g i l l i t e and Upper Sandstone, are beds of shale-breccia. (31) These consist of angular fragments of dark a r g i l l i t e openly suspended i n the g r i t . The fragments are often a foot i n length. The Lower Section: These rooks are extremely uniform and massive. Only a few t h i n bands of shale and shaly sandstone were found, and" these mostly i n the upper half. Much of the shale i s massive, light-gray and indtirated. Sections several hundred feet thick often show no "bedding plane. Cross-bedding i s noticeable i n the upper parts, and becomes prominent i n the upper 2000 feet. The rock i t s e l f i s medium to coarse-grained feldspathic g r i t , examples of which are described below. I t i s gray or greenish-gray i n color, very hard, is o t r o p i c , and often d i f f i c u l t to t e l l from granite on the fresh surface. Poorly sorted bands, represented by spec. 6, are common, i n which isolated pebbles of quartz or granite a few centimetres i n diameter are e r r a t i c a l l y distributed through the g r i t . There are no actual conglomerates along the Similkameen. Specimen 7, from near the base of the section i s t y p i c a l of the lower g r i t . I t i s medium-grained dark gray arkose, t y p i c a l l y isotropic and granite-like. The grains are very angular, 0.2 to 0.6 mm. i n diameter, and are close-packed. An approximate mineral analysis i s as follows: Qtz. - 30%, Ortho-clase - 30, Plagioclase - SO, micas - 5, and matrix - 15. The quartz i s very irregular in.shape, suggesting a small amount of secondary growth. The feldspar i s only s l i g h t l y altered to s e r i c i t e , and a very small amount to kaolin. B i o t i t e flakes are t i g h t l y folded between angular grains. The plagio-clase i s about AbyAng, and i s generally fresh, (see f i g . 2 Apx.) The matrix i s fine s e r i c i t e and some b i o t i t e , l o c a l l y stained with limonite. (32) Middle A r g i l l i t e Section: This middle section i s mostly' fine to moderately coarse arkosic g r i t but contains about a dozen bands of shales. The bands are from two to twenty feet thick, thin-bedded, rarely dark a r g i l l i t e , more commonly li g h t e r colored s i l t s t o n e . The l i g h t gray massive shales mentioned i n the lower g r i t s are also common. Contacts with the g r i t s are abrupt. A meager c o l l e c t i o n of f o s s i l plants was obtained from these shales. The g r i t s i n t h i s section, and i n the section above, are usually strongly cross-bedded. The crossed laminae are of the order of a foot long, i n c l i n e d at angles of 20° to 30° to the normal bedding. They are invariably of aqueous or i g i n . Upper Sandstone Section: This section, about 3500 feet thick, i s on the whole a l i t t l e f i n e r , thinner bedded, and less indurated than the lower g r i t , though of the same feldspathic character. Much of i t i s brov/nish i n color i n contrast to the gray-green of the Lower Section. Xt i s abundantly cross-bedded. Specimen Ho. 8, from the northwest side of the Similkameen i s t y p i c a l of t h i s section. I t i s composed of rounded grains, f a i r l y well sized and averaging 0,5 mm. diam. Clear quartz grains make up only 30%, 40% i s rock grains, including quart-z i t e , chert and very f i n e f e l s i t e s , and 20% i s feldspar, of which fresh orthoclase, microcline, and a l b i t e occur i n that order of abundance. Minor minerals are pyroxene, b i o t i t e , epidote, as d e t r i i a l grains, and b i o t i t e , c h l o r i t e , s e r i c i t e , kaolin and c a l c i t e making up the matrix. (33) No. 11 i s from the same approximate horizon a mile north of the 49th. p a r a l l e l . I t represents several hundred feet of massive beds. I t i s a dark-brown indurated coarse sandstone wit unusual composition, v i z : % • vQuartz . 12 Orthoclase 19 single crystals 37% Plagioclase 6 Fine grained vole.30 B i o t i t e 5 Matrix . 50 • The grains are ragged. The plagioclase, i s fresh, sharply twinned and i s at least as basic as Ab^, The rocks are feldspar porphyries, some with a partly v i t r i c groundmass. They are well decomposed on the outside, and the matrix of the rock i s made up largely of th e i r remains along with secondary chlorite and b i o t i t e . Lithology on Three Brothers Mountain: The lower g r i t of the Roche River formation i s w e l l exposed on the c l i f f s forming the northeast slope of the mountain. Spec. 12 i s an odd type representing a few narrow bands i n the normal coarse g r i t s . I t i s a black fine-grained loosely-consolidated sandstone, composed of poorly sorted angular p a r t i c l of which feldspars are greatly i n abundance over quartz. The plagioclase Is Abg. B i o t i t e and muscovite are each about 5%. The matrix i s c h i e f l y graphitic carbon (10%), with a l i t t l e s e r i c i t e and c h l o r i t e . Here also i s a 100 - foot bed of conglomerate i n the lower g r i t . On approaching i t from higher s t r a t a , the g r i t s are seen to -contain occasional pebbles of quartz or granite queerly i s o -lated i n the much f i n e r material. These increase In size and frequency over several hundred feet u n t i l a close-packed con-(34) glomerate i s formed. The lower contact i s sharp against medium-grained sandstone. The cobbles of the conglomerate are less than four inches i n diameter, f a i r l y well rounded, and composed of vein-quartz, granite, and a minor proportion of eherty volcanics.' I t could not be traced any great distance l a t e r a l l y , and was assumed to be a l o c a l development. Lithology North of Skaist River: Above the basal tuffaceous members, the lower part of the series here i s considerably different from the seetion on the Similkameen. The lower few thousand feet consists of alternating g r i t s , small conglomerates, and a large proportion of shales i n beds 50 to 100 feet thick. The individual g r i t beds do resemble the Roche River g r i t s . Sp. 15 represents a number of thick beds near the base. I t i s a medium-grained g r i t , low i n feldspar, about half quartz, and high i n f e l s i t i c rock fragments. Fragments of dark a r g i l l i t e give the rock a speckled appearance i n hand specimen. There i s considerably conglomerate i n the upper part of the section. I t i s mostly smaller and more open than the A l l i s o n , but one band crossing the Skaist i s given by Gairnes to be 700 feet thick at that point. Thick beds of gr a n i t i c g r i t , very l i k e those of the Roche River, appear above the conglomerate just east of Snass Mtn. Spec. 14 i s t y p i c a l . I t i s a coarse-grained, massive, indurated arkose. I t s analysis i s p r a c t i c a l l y that of a granite, v i z . Quartz - 50, Orthoclase - 40, Plagioclase - 16, B i o t i t e - 8, Matrix - 6, The feldspars are fresh to moderately altered to s e r i c i t e . An unidentified mineral i s conspicuous as irregular grains i n the (35) matrix and replacing feldspars. I t grows i n irregular shapes with uniform orientation, but has no trace of cleavage or crystal form. The optical properties are as f o l l o w s l ; Colorless, non-pleochroic. Index 1,6 Bi r e f . 0.020 * - 2V 80° Opt. positive The matrix i s c h i e f l y s e r i c i t e , with some b i o t i t e and a l i t t l e c h l o r i t e . I t i s d i f f i c u l t to see what gives the rock i t s Induration, since the matrix minerals are soft, and there i s ' l i t t l e Intergrowth of grains, except oceasionly between quartz grains. Much of the induration must be due simply to the Interlocking and mutual cohesion of the grains as a result of high compaction pressures. I t i s possible that the lower part of t h i s seetion &s older than the lower g r i t of the Similkameen section. The swing of some of the attitudes to the west suggests that the main trend i s swinging away from the contact with the Eagle Granodiorite, allowing older strata to appear that were eliminated by f a u l t i n g i n the south. However, not enough structural data has been ob-tained, and the difference i n the sections may represent a true l a t e r a l graduation. The s i t u a t i o n i s further complicated by the fact that a large f r a c t i o n of the section i s absorbed by intrusives. Lithology i n Coquihalla Area: The Lower Cretaceous rocks des-cribed by Cairnes (14, 12), north of Tulameen River may be partly equivalent to the Roche River formation. The section here tot a l s 8000 feet, and consists of thick massive g r i t beds, conglomerates, and thick s l a t y shale beds. The conglomerate below Romeo was Iproperties determined by C.O.Swanson. (36) mentioned i n connection with, the A l l i s o n , Cairnes describes i t as a granite conglomerate, with boulders ;six to eight inches i n diameter, mostly unsheared plutonics, i n a matrix of granitic arkose. Another conglomerate with a higher proportion of volcanic and chert -cobbles occurs near the base of the section (faulted): against the Ladner slates along the Cedar Creek - Carey Creek divide. This conglomerate apparently extends south toward the Tulameen River, Though the g r i t s are feldspathic, quartz i s i n excess over feldspar, and i n that respect they are different from the g r i t s of the Ladner Series. Chuwanten Formation General: Conformably above the upper sandstone of the Roche River formation there i s a rather persistent belt of purplish to chocolate colored rocks. These are sandstones, a r g i l l i t e s , and t u f f s , a l l showing the purple colour. They are overlain by conglomeratic g r i t s and sandstones of a different character from the Roche River g r i t s . / • The purple beds were f i r s t noted along the Similkameen valley. They are well exposed i n a minor f o l d just south of the Similkameen and east of the Chuwanten. The horizon was crossed at several points west of Three Brothers Mtn, South of the Similkameen they and the overlying strata are apparently cut off by the Chuwanten f a u l t . They have not been noted along or north of the Skaist River. Lithology: The 'purple beds' may be arkose g r i t (spec. 19), soft massive a r g i l l i t e , or t u f f (spec. 17), Typically the (37) three types are interbedded i n thi n intergrading beds a few inches to a foot thick. : Spec. 17 i s an unsorted pyroclastic. Angular fragments of quartz, oligoclase, and a l i t t l e augite and magnetite, l i e i n a matrix of f i n e r crystals, glass, s e r i c i t e , clay, and c a l c i t e ( i n large grains), with hematite and limonite. The ' a r g i l l i t e s ' are probably t u f f s also. Spec, 19 i s from the same horizon eleven miles northwest. I t Is a reddish fine-grained arkose of the following composition: Qtz. - 30%, Orthoclase - 30, Plagioclase - 17, Matrix - 16, Rocks, Carbon and pyrite - 7, and a few grains of t i t a n i t e and magnetite. The feldspar i s fresh and angular. Plagioclase i s Abg. The grains invariably have a rim of fine hematite, which, with mica and clay, forms the matrix. The strata above the purple beds are medium to coarse conglo-meratic sandstone. They are feldspathie and l i t h i c i n composition, but are less g r i t t y and indurated than the Roche River rocks. Conglomerate i s very common a l l through, and occasionly forms beds f i f t y feet or more thick. I t i s usually 'open' with much matrix and forms l e n t i c u l a r and e r r a t i c beds. False bedding and small scale cut and f i l l are common. Pebbles are subround, less than four inches i n diameter as a ru l e , and are cherts and volcanics, with a minor amount of granite. Breccia of shale i s also common both with the conglomerate, and dispersed i n the sandstone. Structure i n the Dewdney-Pasayten Structure i n Coquihalla Area: Strikes i n the Ladner Series are generally N 35° W; dips are high southwest to v e r t i c a l . The basin contains a tight syncline and a n t i c l i n e plunging s l i g h t l y (38) southeast. The Dewdney Greek Series forms a large close syncline with some minor folds and f a u l t s . Gn Tulameen Mtn. there i s evi -dence of overthrusting from the SW to the ME on a plane s t r i k i n g N 45° W and dipping 20° SW. The Gretaceous strata s t r i k e K 15° W or, on the average, 20° nearer north than the Dewdney. The opposite situ a t i o n ob-tains i n the Similkameen area, where the Dewdney strikes closer to north than the Pasayten. The seotion NW of Romeo shows very uniform attitudes of N 35° W 40° - 60° W. On the Coquihalla-Carey divide the structure i s a compressed syncline with dips of 50° on the flanks increasing to v e r t i c a l i n the a x i a l part. The syncline extends south into the area just north of Tulameen River, On the east side of t h i s area, against the Eagle G-rano-d i o r i t e , dips are low westward. There i s evidence of an important f a u l t along the Coquihalla va l l e y , o f f s e t t i n g the .Cretaceous areas and bringing the small conglomerate areas below Romeo into t h e i r present strung-out position. There i s a discordance of dips.'between the Cretaceous and the Ladner, indicating a faulted r e l a t i o n or possibly an uncon-formity. The r e l a t i o n between the Ladner and the Cache Or. i s not d e f i n i t e l y known. Cairnes indicates that there i s no great d i f -ference i n intensity or trend of folding between the'two. There are no pre-Ladner granites i n the area, but the Cretaceous (?) conglomerate near Hope overlies older gneissic granite (see page 50). Both Ladner and Cretaceous rocks contain granitic detritus. ( 3 9 ) . Both series are intruded by a large granite to quartz-d i o r i t e batholith to the north, and several smaller bodies to the south, of Coquihalla River. The Eagle d i o r i t e and quartz-d i o r i t e cuts the Cretaceous rocks i n the area HW of Romeo and southeast -of Iago. With the Eagle Granodiorite, the r e l a t i o n i s not so clear. Faulting along the contact may have disposed of contact metamorphosed areas. Cairnes (14) thinks that the sediments are older. However, on the Railroad' Creek-Kelly Creek divide (12, p. 98a) they appear to overlie the granodiorite uncon-formably. . The Coquihalla volcanics overlie the Cretaceous with d i s -t i n c t unconformity. Structure along Skaist Valley: The Dewdney Series, with probably some Ladner i n the west, i s folded into a single syn-cline s t r i k i n g about N 15° W. The dips are steep easterly on the west, v e r t i c a l i n the centre, and moderate westerly on the east. There i s also considerable minor folding and f a u l t i n g . The Pasaytenj or 'Cretaceous' pf Cairnes, i s i n the form of a single homocline. Strikes of K 50° W, with moderate south-westerly dips, p r e v a i l i n the central part of the .section. On the east, near the granodiorite they are N 40° W and dipping v e r t i c a l or very steep easterly, Cairnes observed a discordance of attitude between the Dewdney and the Pasayten, and indicated a faulted r e l a t i o n . The fa u l t may not be simple, since on Snass Mtn, rocks of Roche River type are faulted down against the Hampton Cr, formation along a plane s t r i k i n g I of north and dipping steeply E. Cairnes f a u l t appears to be west of this and s t r i k i n g 20° west of north. (40) The rocks on the western peak of Snass Mtn, (spec, 25) are somewhat l i k e the Dewdney t u f f (spec, 26) and very different from the green breccia on the east Pk, of Snass, I t may be that Cairnes' f a u l t extends between these two peaks. Also here a conglomerate almost i d e n t i c a l with t y p i c a l A l l i s o n Conglomerate overlies both the volcanic formations with apparently a faulted r e l a t i o n . In t h i s area the Dewdney i s d e f i n i t e l y unconformable on the Cache Cr. The r e l a t i o n with the Eagle GranodioEite i s s t i l l not d e f i n i t e . There i s good evidence of some f a u l t i n g i n the crushing of the beds. There i s no evidence of intrusion. The argument against simple unconformity i s the steep dips adjacent to the contact (50 - 90°), and the uniformity of such dips for some distance away from the contact. I t i s hardly probable that a surface of unconformity could be t i l t e d to such an angle. A number of l a r g e . s i l l - l i k e bodies of d i o r i t e or syenite porphyry intrude "'the Pasayten north of Skaist valley. Individ-ual s i l l s range up to several hundred feet thick, and the agg-regate thiekness i s several thousand feet. Structure i n the Similkameen Area.-Deformation of the Dewdney: A well-defined syncline trending N 20° W i a the main structure. This syncline i s found on the Skyline t r a i l and again west of A l l i s o n Pass, and i s probably continuous with the one i n Skaist valley. Along Skyline t r a i l , strikes are generally about N 10-20° W. Dips vary, but are generally stegp, and there are other folds west of the main syncline. Minor f a u l t s along s t r i k e or nearly so are also common. The dips adjacent to the L i t t l e Muddy f a u l t are steeper and (41) more northerly than those i n the Pasayten rocks east of the f a u l t . Attitudes i n the Pasayten: The Pasayten Series presents a gigantic homocline of 'truly embarassing' 1 dimensions. This i s shown i n the cross-section on page 45. Between the Eagle Granodiorite and the L i t t l e Muddy f a u l t , strikes vary l i t t l e from N 35° W and dips are between 50 and 70 degrees southwest. The only departures are found i n certain thin-bedded f o r -mations. In the interbedded t u f f s and g r i t s of the Chuwanten formation, at a point just south of Similkameen valley, strikes are observed to swing from N 55° W to a l i t t l e east of north then back again i n a horizontal distance of half a mile. At the same time dips change from 50° SW to 20° NW and back again. These changes were interpreted to represent a NW plunging minor f o l d on the limb of a major homocline. A similar r o l l occurs i n the thin-bedded s t r a t a of the Frosty formation, 7 miles south of A l l i s o n Pass. Here however strikes swing to the west while the dips f l a t t e n , indicating a SE plunging f o l d . Faulting: Two large f a u l t s break the homocline. The f i r s t i s the Chuwanten f a u l t . As far as i t was traced i t i s a s t r i k e f a u l t . I t s dip was not determined, but i t could not be very f l a t . I t s presence i s indicated by shearing and crushing i n adjacent beds. Considerable offset i s indicated i n the apparent truncation of the Chuwanten formation along Chuwanten valley. The assumed based on Paleontology, The Roche River formation east of the f a u l t i s much younger than the Hampton Creek beds on the west, so that a large upthrow of the 1, Read R. A. Daly - 25, v o l . 1, p. 480. (42) western block i s indicated. The direction of the minor f o l d i n the Chuwanten formation i s i n agreement with such a displace-ment. The stratigraphic displacement must be of the order of 25,Q00 feet. The second f a u l t , referred to as the L i t t l e Muddy f a u l t , i s a s t r i k e f a u l t south of A l l i s o n Pass, but north of t h i s point i t trends more northerly, crossing the strike at a small angle. A few miles north of A l l i s o n Pass i t duplicates the A l l i s o n conglomerate and apparently cuts i t off completely further north. This would require a s p l i t i n the f a u l t as indicated on the map. The dip of the f a u l t must be steep as i t s trace does not vary noticeably with topography. The only indication of displacement i s the discordance of attitudes and the offset i n the conglomerate. Paleontology shows that part i f hot a l l of the Dewdney i s older than the Hampton Creek, so the west block i s again up-thrown. The minor f o l d i n the Erosty formation supports t h i s . The stratigraphic displacement may be only 10,000 feet. The northward continuation of the Chuwanten f a u l t has not been determined. The L i t t l e Muddy f a u l t i s no doubt the same f a u l t that Cairnes maps as separating the Dewdney and Pasayten i n Skaist Valley, and which may extend between the Peaks of Snass Mtn. (see p. 40). The f a u l t just east of Snass Mtn. and apparently running into the L i t t l e Muddymay be the Chuwanten. I t has been strongly suspected that there are faults within the Roche River formation, causing the excessive apparent thickness. They would be hard to f i n d i$. such monotonous lit h o l o g y . Wo such faults were found i n 1941, though careful sections were made i n good outcrops along both sides of the Similkameen. There are (43) numerous minor faults s t r i k i n g K 60° E and dipping steeply. Relations to Hozameen Series:- On the west the Dewdney rocks are separated from the Hozameen (Cache Creek - Paleozoic) by an obvious f a u l t s t r i k i n g east of north and dipping v e r t i c a l l y , with the west side upthrown. This fault swings west and gives way to an unconformable contact near Shawaturn Mtn. (Camsell, 6). More fa u l t i n g i s indicated north .of here. See also p. 18, 38. Relations with.tii'eoEagle Granodiorite: The exact relations have not been determined. Faulting i s suggested i n several l o c a l i t i e s . Simple unconformity i s improbable because the high dips near the contact would necessitate t i l t i n g of the plane of unconformity to a high angle; an operation not easy to explain. The d i s t r i -bution of the batholith and the prevailing gneissic structure nearly p a r a l l e l to the attitudes i n the Pasayten Series, suggests that i t i s younger, and was emplaced along a zone of f a u l t i n g between the Pasayten and the older Tri a s s i c rocks. I f i t i s older, then there must have been strong f a u l t i n g along the east of the Cretaceous wi th the east side u p l i f t e d . Younger Intrusives: The Castle Mtn. stock of about 10 sq. miles extent cuts the Dewdney Series at the 49th p a r a l l e l . I t i s t y p i c a l granodiorite, and stoped i t s way, i n the t y p i c a l 'Daly' manner, into the roof rocks, with no disturbance of the bedding (see Daly, 25, p. 492). Several other stocks of d i o r i t e and quartz-diorite cut the Dewdney Series, and s i l l s of d i o r i t e to syenite make up a quarter of the section i n some places. In the PasaytBn there are a large number of s i l l s and several chonolithic bodies of syenite to d i o r i t e porphyry. They (44) are very similar i n megascopic appearance throughout the series. Origin of the Structure: The lith o l o g y a l l through the succession suggests that deposition occurred i n a narrow basin (40 - 50 miles) The apparent absences of Dewdney beneath the Pasayten on the east suggests that the basin migrated eastward toward an actively r i s i n g land area. The absence of more Cretaceous rocks to the east and the great thickness r e l a t i v e to the probable width of the basin and the massiveness of most of the Pasayten preclude the p o s s i b i l i t y of the entire Pasayten homocline being merely the limb of a f o l d . I t i s li k e l y . t h e n that forces of deformation transverse to the basin were accompanied by a v e r t i c a l upward movement i n the eastern block, so that the formation was deformed into massive t i l t e d blocks. In the Dewdney, and i n the Northern part of the Pasayten, where the formations were not so massive and blocky, ordinary folds were produced. The hypothetical sequence of events i s indicated i n the diagrams below the cross-section on p. 45, Time of Deformation: The highest strata represented i n the Pasayten are probably low i n the Upper Cretaceous, The Coquihalla volcanics and the Princeton volcanics, though moderately folded themselves, are unconformable with the Pasayten, The age of the Princeton volcanics i s Oligocene or thereabouts. A great amount of erosion i s indicated after the deformation and before the Princeton volcanics were l a i d down. In the Harrison Lake area (Crickmay, 23), the main folding of the Cascades i s con-sidered to be post-Eocene, as i t also appears to have been on the coast" (see p, 96), This may well be true i n the present area. (45) Gross S e c t i o n along A^JLgajLJLL-QJLD C T f d r' 9^^ Scale: Horiz. and Vert., l l n . 2 miles. - Hozameen S e r i e s E - Hampton Creek J - Tulameen Ser i e s F - A l l i s o n K - Eagle Granodiorite a - Fr o s t y L - Dewitney Series H - Pasayten Vole. Roche Elver Chuwanten Princeton Volcanics Development o f S t r u c t u r e : S c a l e appro?; 1 i n . 4 miles• 5. " F a u ^ ' i i i ^ r t S ' 4. C o n t i n u e d f a u l t i l t i n g . U p l i f t , i n t r u s i o n (46) Conditions of Deposition: The conditions of deposition i n the Ladner and Dewdney Series have already "been discussed. The essential point i s that source lands stood at moderate or low elevations and were not far from s i t e s of deposition. Most of the material was d i r e c t l y or i n d i r e c t l y the product of volcanic eruptions, and was mostly fine material deposited in.marine waters. The Volcanics of the Hampton Creek beds represent more violent a c t i v i t y or volcanics closer to s i t e s of deposition. Normal sediments Interbedded with the volcanics l o c a l l y show the effects of greater r e l i e f i n the soufcce areas. They were deposit-ed i n a marine environment. The A l l i s o n Conglomerate, although not unconformable on the underlying beds, records an u p l i f t of great magnitude i n the source areas. I t i s not easy., to imagine the formation of such a thick conglomerate. The boulders must have been transported many tens of miles by strong currents. The conglomerate must have grown out gradually as a massive sheet from the base of the mountains. This would take time, and the conglomerate may be expected to overlap strata of successively younger age away from i t s sources. An easterly source i s assumed from the evidence of structural o r i g i n indicated above. Strangely enough, fine sediments, along with impure g r i t s , followed the conglomerate, and these were deposited In marine environments also. The conditions of deposition of the Pasayten Volcanic member were discussed on page 29, The Roche River formation i s essentially arkose. The (47) essential conditions for the formation of arkose are; (4, 93) (1) granitic terrane ( 2 ) disintegration without decomposition (5) erosion and deposition with l i t t l e loss of feldspar To these may be added i n the present case; erosion and deposition with l i t t l e rounding of the grains, and under such conditions that f i n e r shale producing materials are -virtually eliminated from the matrix of the arkose and from interbedded strata. The f i r s t requirement meets obstacles, Granitic rocks of pre-Cretaceous age do not form very large areas east of. the basin except to the south. The Eagle Granodiorite i s narrower than the basin i t s e l f . I t i s possible that the Eagle formerly occupied a larger area, widening eastward over the present area of Triassic rocks, Some gran i t i c areas are covered by Tertiary lavas, The second condition i s f i l l e d i n various climate types but p a r t i c u l a r l y i n a dry, desert climate. This, more than other climate types would y i e l d a continuous supply of crystal fragments without much fine material. The t h i r d and additional requirements require rapid erosion and deposition with a minimum of t r a v e l . Water was the agent of deposition as.indicated by the character of the cross-bedding and the shale beds. I t i s l i k e l y , however, that much of the basin was dry. Sediments would arrive intermittently by means of v i g -orous ephemeral streams, eroding and depositing the coarser elast i c s rapidly, and carrying the muds into more distant areas. I f , as i s l i k e l y , the source areas were only p a r t l y granite, large volumes of material must have been carried away i n solution and as mud, beyond the l i m i t s of the basin. Wind may have (48) contributed to the removal of the fine material. Dune cross-bedding has not been recognized, but i t could e a s i l y be over-looked i n rocks which are almost isotropic to the agents of weathering. The Middle A r g i l l i t e section indicates a time i n which a water surface was more general. Normal shales were l a i d down i n t h i n beds over large areas. Possibly an epoch of wetter climate i s indicated. The Upper Sandstone indicates a return to subaereal con-ditions. Abundant aqueous crossbedding Indicates rapid depo-s i t i o n . The Chuwanten formation records an epoch of voleanism i n areas some distance from the basin. The color of the otherwise normal clastios i n t h i s formation i s not considered to be of the same o r i g i n as i n normal red beds (77). I t Is more l i k e l y due to hematite from the volcanic eruptions, preserved i n the absence of organic matter. The Upper parts of the Chuwanten strongly suggest a wett©r climate, active and continuous streams, and rapid deposition partly above water l e v e l . -Although the Eoche Eiver deposits suggest rapid deposition, that applies only to single beds. Intervals between beds may have been large and the formation as a whole representative of a r e l a t i v e l y long time. The fact that so l i t t l e coarse con-glomeratic material i s intermingled with the g r i t s , and that when t h i s does occur i t i s mostly of hard rocks resistant to granular disintegration, indicates that the production of sed-iments was slow. Either single grains or boulders too large to (49) transport were produced. The ephemeral streams acquired an easy load of the smaller materials and l e f t the larger "blocks, only i n a few cases acquiring intermediate-sized materials. The opposite i s true of the Chuwanten formation where rapid continuous erosion of the lands gave a l l sizes and vari e t i e s of material, and deposited them chaotically. Age: Daly (25, p. 486-439) made a number of small f o s s i l plant collections from the Pasayten Series, and found a few marine invertabrates i n what i s now the Hampton Creek formation. These established the age as Cretaceous, and possibly Upper Cretaceous i n part. During the season of 1941, Rice"'* made extensive collections from the Roche River, the Hampton Creek, and the Dewdney rocks. The Roche River f o s s i l s were plants and indicated Albian age (Late Lower Cretaceous). The other f o s s i l s were invertabrates. Those from the Hampton Greek are Neocomian and/or Barremian (Middle Lower Gretaceous). In the Dewdney, some collections are s l i g h t l y older or nearly equivalent to the Hampton Creek, while others are d e f i n i t e l y of Upper Jurassic age. The structure r e l a t i n g the f o s s i l l o c a l i t i e s i n the Dewdney has not been com-pletely worked out, but i t i s almost certain that a complete t r a n s i t i o n exists. -'•Personal communication. - Plants were determined by B e l l , animals by McLearn. (50) LOWER CRETACEOUS WEST OF THE DEWDNEY-PASAYTEN AREA Conglomerate on the Fraser River Near Hope A narrow band of conglomerate extends p a r a l l e l to the Fraser River on the west side of the valley for nine miles north and two south, of Hope. A small outlying continuation of the same band Is found on I s o l i l l o c k Mtn.' f i v e miles south of Hope. North of Hope the band follows a s l i g h t topographic depression about 1000 f t . above, and p a r a l l e l to the main valley. Between Emory Creek and American Creek i t l i e s along the con-tact between older sheared granodiorite on the east and Paleo-zoic schists on the west. South of American Creek i t is bounded on the east by the schists and on the west by younger intrusives. The odd fact i s that the younger intrusive comes in i n such a way that the narrow trend of the conglomerate i s unaltered. South of the Fraser i t overlies older granodiorite again for a mile and i's then cut off by Sil v e r Creek valley (and a younger i n t r u s i v e ) , to reappear at an elevation of 4000 to 6000 feet on I s o l i l l o c k Mtn. Just north of the Fraser i t strikes o / about north and dips 75 west. Horwood (51) states that the conglomerate i s largely made up of material derived from the underlying intrusives, with l i t t l e from the Paleozoic rocks. Cairnes (14) describes the part near Hope and on I s o l i l l o c k Mtn. as chert conglomerate, with mainly cobbles of Caehe Creek chert, and less than half plutonics in a matrix of arkose. Except where Indurated near igneous contacts, the rock breaks around the fragments, i n contrast to the A l l i s o n conglomerate. It i s intruded, with characteristic induration and meta-(51) morphism, both by the younger Gretaceous batholith south of Hope and by the Tertiary Quartz-diorite on I s o l i l l o c k Mtn. There is no evidence for dating the conglomerate other than that i t overlies post-Carboniferous intrusives and is cut by younger Cretaceous intrusives. I t may represent the same orogenic a c t i v i t y that produced the A l l i s o n , and may have once been continuous with i t , extending i t to the west side of the Dewdney-Pasayten basin. Its peculiar d i s t r i b u t i o n has been thought to be related to graben faulting along the Fraser valley, but in this loc-a l i t y the only evidence for such fau l t i n g i s the d i s t r i b u t i o n of the conglomerate i t s e l f . The Tamihy Series A thick series of sedimentary rocks of Mesozoic age is mapped over an area of some 100 square miles i n Washington (24) A small area extends into Canada near Church Mtn. The series i overlain by the Quaternary volcanics of Mt. Baker in the south, and by Tertiary sediments i n the west. On the north i t i s apparently unconformable on the Chilliwack S eries, and early Mesozoic formations. No complete section has been made. The rocks apparently are mainly feldspathic sandstones. Both Smith and Calkins (87) and Daly (25, p. 519) remark on the s i m i l a r i t y of the rocks to some of the members of the Pasayten Series. The age i s believed to be Jurassic on meagre evidence. The structure has not been worked out i n s u f f i c i e n t d e t a i l to commit the entire series to that age. I t may represent a (52) separate basin of deposition of the same period and character as that of the pasayten. Cretaceous Rocks at Harrison Lake The discovery, dating, and mapping of these rocks and related structures i n the area around and south of Harrison Lake is mainly the work of C.H. Crickmay (23). He did much of the investigating privately on his own time. Crickmay maps two formations, comprising 5000 f t . of sand-stone and agglomerate, i n the Lower Cretaceous. They rest with mild unconformity on Upper Jurassic sedimentary formations. A two-mile-wide s t r i p arcs westerly from the shore of the lake opposite Long Id. A portion appears on the island, and another portion on the peninsula.near the south end of the lake. These areas are bounded westerly by Jurassic rocks and easterly by a confusion of faulted fragments of various formations class-i f i e d as •Schuppen'. Paleozoic and successively younger formations on the east are considered to be overthrust onto the Cretaceous along a f a u l t which dips east at a moderate angle, the trace of which i s concave westward with a radius of about 30 miles. The Cretaceous formations contain debris of the Coast Range intrusives and overlie, with very s l i g h t unconformity, Jurassic strata which are cut by the same intrusives. Further-more, strata of Early Tertiary (Paleocene) age are involved i n the f a u l t i n g . Crickmay thus concludes that high-angled structures did not develop when the Coast Range intrusives were emplaced, and were not i n fact developed t i l l 'Laramide'. I t is much more l i k e l y that the period of orogeny was Early Oligocene, as on Vancouver Island, and unrelated to the 'Laramide' of the Rockies. (53) Possible Cretaceous Rocks Worth of Vancouver In the Black Tusk area, 40 miles north of Vancouver, W. H. Mathews (65) investigated a sedimentary series which contains abundant granitic material i n i t s conglomerates, and i s also cut by younger granite. His section extends from the Cheakamus valley, at the confluence of Rubble Creek, east for about fiv e miles, beyond which the series extends s t i l l further. The section includes about 6000 feet of strata and is not complete. I t runs as, follows, from the top down:-3500 f t . -• Black a r g i l l i t e with some sandstone and g r i t . 1000 f t . - Grey argillaceous sandstone. 100 f t . - Boulder conglomerate with granite. 1500 f t . - Green tuffaceous sandstone. The structure i s a broad an t i c l i n e s t r i k i n g N 30° W. The series overlies with apparent unconformity a more folded series of quartzite, slate and limestone, considered to be equivalent to the Cadwallader Series (18). Quartz-diorite intrusives of batholith size cut the series i n the notheast. A pelecypod f o s s i l of Jurassic or Cretaceous age was found by Mr. Mathews. There i s no other useful age evidence. Mathews believes the series may be corellated with part of the Britannia Group. This group occupies a large area twenty miles south of the Black Tusk area. I t also contains meagre fragments of e a r l i e r granite and i s intruded by younger granite. It is thought to be Triassic or Jurassic i n age and equivalent to the Vancouver Group (LeRoy, 58). Several other smaller areas of volcanic and sedimentary rocks with the same relations to the granites are found between the Black Tusk area and Vancouver. (54) Lower Cretaceous on Vancouver Island Distribution and General Remarks; A number of small widely separated areas of sediments of Lower Cretaceous age occur along the west and north coast of Vancouver Island. There is,a small area on Flores Id.; an area of 30 square miles underlying the peninsula back of Estavan Pt.; small areas on Nootka Id., Barrier Id., and near Cape Scott; and several faulted remnants of a once large area around the arms of Quatsino Inlet.. In the l a t t e r case the deposits are only a few miles from the Upper Cretaceous on the east coast between Port McNeill and Hardy Bay. (Suquash coal area, see p. 84). The northern areas were described by Dawson in 1886 (29). Dolmage (33) i n 1918-19-20 described a l l the areas on the west coast. Gunning i n 1*929 (47) examined the sediments on Rupert Arm and West Arm. Lithology; The 'rocks are marine sediments. Sandstone predominates over shales, fine calcareous beds and conglomerates In Quatsino Sound there i s about 3600 feet of s t r a t a , including a few thin coal seams (37). The sandstone consists of well rounded quartz and highly weathered feldspar. The conglom-erate has boulders of the Vancouver volcanics and of granodiorit Strueture; Dips are generally low. Strikes average N 45° - 60° W, p a r a l l e l to those i n the Vancouver volcanics, and to the present shore. High dips are noted i n the Quatsino area, where there i s also a great deal of f a u l t i n g . The deposits invariably overlie the Vancouver volcanics. The relations between the two are certainly unconformable, but the character of the surface of deposition i s not noted. They (55) are confined to low elevations i n the same way as the Kanaimo rocks, as though the surface of deposition approximated the present surface. They are not i n contact with the batholithic rocks, but contain boulders of granodiorite i n their conglom-erates, so are no doubt younger than the main intrusives. The relations with the younger Gretaceous at Suquash are unfortunate not known. The areas are too small to compare degree of folding but there is certainly more deformation i n the Quatsino area than the nearby Suquash area. Age; .Marine f o s s i l s from various l o c a l i t i e s give the age as Lowest Cretaceous, or possibly Upper Jurassic. Dolmage found the invertebrate Aucella p i o c h i i ovata near Estavan Pt. This may be Upper Jurassic. Aucella c r a s s i c o l i s i s common i n the Quatsino area and i s 8 Lower Cretaceous. There i s no reason to suppose that a complete t r a n s i t i o n from Jurassic to Cretaceous i s not represented here, Origin; The deposits record a marine invasion which con-fined i t s e l f to the present coastal area. The fact that the Upper Cretaceous deposits bear essentially the same r e l a t i o n to the older Vancouver volcanics suggests that erosion was con-tinuous from the Jurassic through Lower Cretaceous, with only a minor interruption i n the areas where these Lower Cretaceous deposits were formed. The Suquash deposits, and the rest of the Nanaimo Series, were not formed i n open marine waters, but i n shallow estuaries. The Lower Cretaceous deposits were near-shore, but i n communication with the open sea. (56) CRETACEOUS ROCKS EAST OF THE MAIN BELT The Spence's Bridge Volcanics Distribution and General Remarks; 'Spence's Bridge Volcanics' i s the name given to. a group of volcanics of diverse character exposed along the Thompson valley for seven miles above and ten miles below Spence's Bridge. These were mapped as Tertiary by Dawson (31), but Drysdale (38) found f o s s i l s in certain members that gave the age as Upper Jurassic or Cretaceous. How much of the area that Dawson mapped as Tertiary north of the Tti Thompson is actually Spence's Bridge, i s not known. The narrow s t r i p through Glen Fraser and north of here i s considered to be Tertiary. The area to the south of the Thompson i s also i n d e f i n i t e . Between Thalia"-and Brodie on the Kettle Valley Railway, and south to Thynne Mtn., Cairnes (11) mapped a series of pyroclastics and flows' which were structurally and l i t h o l o g i c -a l l y l i k e the Spence's Bridge Volcanics, but on account of their freshness he thought they must be Tertiary. In 1939, H. M. A. Rice found' tuffs and sediments at Kingsvale which contained f o s s i l s of Late Lower Cretaceous age. These were, i n some respects l i t h o l o g i c a l l y i d e n t i c a l with the tuffs and breccias of Cairnes between Thalia and Brodie. The Kingsvale area was very small, but other areas to the east and north no doubt belong to the same formation. . Lithology; Along the Thompson Valley the estimated thickness of the series i s about 5000 feet. The lower part of the section consists of massive breccia, tuff and flows, with some coarse ( 5 7 ) conglomerate containing granite boulders as well as volcanics. Above this are rhyolite tuffs and lavas. The tuffs are said to have peculiar fine-twisted lamination surfaces. On top of these are more andesitic lavas, both vesicular and amygdaloidal, interbedded with argillaceous sediments. There i s also i n one l o c a l i t y a conglomerate of sub-angular granite and other rocks, i n an arkose matrix. The rocks around Kingsvale have some s t r i k i n g s i m i l a r i t i e s , but unfortunately they have not been s a t i s f a c t o r i l y brought together into a definite formation. Angular conglomerate with-tuff matrix has been noted, and interpreted as talus breccia. Rhyolite flows and tuffs with twisted laminations occur south of Kingsvale. At Kingsvale, and again a few miles southeast of Brookmere, a characteristic type of deposit i s noted. This is a completely unsorted fine-breccia to ash deposit forming irregular beds in normal sandstones and shales. They show pl a i n l y the effect of chaotic and sudden v e r t i c a l deposition into a sedimentary basin. Small trees, now converted to a hard carbonaceous rock, have been buried by the a s h - f a l l s . Since branches are absent, and the trees are prostrate, and there.are no detailed structures observed, i t seems evident that the trees were burned and knocked down before b u r i a l by the hot ash. Specimen 28 i s t y p i c a l of this material. I t i s a rhyolite l i t h i c t u f f . The fragments are from a centimetre i n diameter down to f i n e s t ash. There is an obvious absence,of sorting. The larger fragments are l i t h i c , and form 30 to 50% of the rock. One t h i r d i s made up of c r y s t a l fragments, and the remainder is (58) . unresolved matrix. Most of the rocks are f i n e l y c r y s t a l l i n e masses of a l k a l i feldspar and quartz. Some are vitrophyres, others have the glass d e v i t r i f i e d . There are also many frag-ments of pl a i n glass. The matrix i s unresolved clayey material, The coarse beds alternate with beds of hard, fine to coarse tuffs which are c l e a r l y transported and sorted by water, but rapidly deposited. They contain the carbonized remains of plants and leaves twisted at a l l angles to the bedding. Other beds are normal sandstones and shales, with good f o s s i l leaves. Cairnes reported a preponderance of intermediate or andesitic pyroclastics. He also found andesite flows with open and partly f i l l e d vesicles; a feature strongly suggesting Late Tertiary age. Structure; Along the Thompson valley the rocks form a synclin-orium 14 miles wide, s t r i k i n g NW and SE. There are additional broad anticlines and synclines. Here they overlie Cache Creek rocks and granitic intrusives i n the west and south with definite unconformity. Their r e l a t i o n with the so-called Cretaceous at Botanie Creek i s unfortunately not known. They are overlain unconformably by Tertiary volcanics a few miles south of the Thompson River. Origin; The conditions of the period were dominantly volcanic. The eruptions were mostly of an explosive character, apparently of the Peleean type. Quieter eruptions came with the andesite flows. The area contained bodies of fresh water of unknown size , but presumably small, since leaves and trees are found i n them. These were receiving small amounts of normal sedimentary material. (59) Age; Drysdale's f o s s i l plants indicated Lower Gretaceous age, though some species were noted to have a Jurassic aspect. Knowlton stated that they were "certainly lowest Cretaceous i f not indeed Upper Jurassic". His f o s s i l s were fragmentary and poorly preserved. Fossils from the tuffs at Kingsvale, deter-mined by B e l l i n 1941, give the age d e f i n i t e l y as Aptian or Albian. The c o r e l l a t i o n between the two l o c a l i t i e s rests on lithology. I t must be concluded that the time relations and the di s t r i b u t i o n of the Spence's Bridge Volcanics is s t i l l a matter to be worked out. The so-called Cretaceous Rocks at Ashcroft A series of sedimentary rocks, for some time thought to be of Cretaceous age, occupies a small separated basin of f i f t y square miles in the r e l a t i v e l y low subdued area around Ashcroft. Dawson (31) examined the rocks i n 1894. He found no f o s s i l s , but corellated the rocks on l i t h o l o g i c evidence with the Fraser River Series, which wer.e known to be Lower Cretaceous Evans (42) wrote on the stratigraphy of the 'Cretaceous' of the area, but added nothing to the age determination. Drysdale (38) likewise found no he l p f u l f o s s i l s . Crickmay (22) studied the section many years la t e r and found the rocks " b r i s t l i n g " with f o s s i l s . He found that the conglomerate which Dawson considered basal to the Cretaceous belonged actually i n the middle of a Jurassic succession, and uha a much smaller conglomerate separated the Jurassic from the Tri a s s i c . He describes the r e l a t i o n with the Triassic as a low-angle unconformity. A l l the supposed Cretaceous becomes (60) Middle and Upper Jurassic. To one unversed i n paleontology, Crickmay's dating of the strata i s far from convincing. Out of a dozen or more species which he describes from each of several l o c a l i t i e s , only one or two species determine the age; the rest are new species. There are also anomalies in one or two cases; a Triassic crinoid in one l o c a l i t y and an aucella i n another. "Much of the v a l i d i t y of the work rests on the correct l i t h o l o g i c c o r e l l a t i o n of small sections over considerable hor-izont a l distance. Evidently some of his sections were d i f f i c u l t . In one case he records only 200 feet of strata i n a horizontal mile, whithin which Triassic outliers poked through. The writer cannot c r i t i c i z e Crickmay's work since he has not been over the ground, but he can say that the case as pre-sented i s a l i t t l e unconvincing. One of the most'interesting results of the work, i f f i n a l l y correct, i s the indication of granitic rock being ex-posed i n pre-Upper Jurassic time, since cobbles of quartz-diorite are found i n the conglomerates of•Crickmay's Basque formation. Crickmay believes that the material came from the east - from the Central Cordilleran Geanticline which made i t s appearance in the Jurassic (84). Dawson, however, notes sub-angular breccia, containing granitic rocks, at the base of his section. These could not have travelled as far-as an eastern source would require. Lithology: About 5000 feet of strata are represented. They are c h i e f l y dark shales and sandstones. In the lower part of the section, Dawson notes greenish hard sandstone or q u a r t z i t e 1 ^ —' •foozle S-c (PI 6//t>u/'Uj (61) forming a large part of the formation. Some of these rocks are arkose, composed of granitic debris; others are diabasic i n composition and are called diabase t u f f s . A specimen from the Ashcroft area and several from the Fraser River Series near L i l l o o e t are described i n Dawson's report (31, appx. 1). They are c l a s t i c rocks composed of plagioclase, augifee, auartz and porphyrite rocks. Dawson considered them to be graywacke from the erosion of older volcanics. The s i m i l a r i t y of the material i n the Ashcroft' and i n the L i l l o o e t areas is noteworthy. They r e c a l l the graywacke described by Dolmage north of Ghilko Lake (see p. 71.). Graywackes of p i c r i t e derivation are described from the Copper Creek area 20 miles east of Ashcroft. (see p. 62) Structure; Dawson interpreted the structure as a syncline s t r i k i n g about north. Low westerly dips prevail on the east side of the basin, steep overturned westerly dips pre v a i l i n the west, with considerable f a u l t i n g and crushing against the older rocks. •""The word quartzite i s evidently used in the sense .of an indurated c l a s t i c with qu a r t z i t l c fracture, regardless of composition. Cretaceous Rocks of the East-Half of the Ashcroft Area 1 A number of separated areas of undated sedimentary and associated volcanic rocks occur i n the east-half of the Ashcroft Sheet. They have been referred to the Cretaceous on structural evidence. The largest of these forms a belt three by ten miles •^The information given here was obtained by personal comm-unication with W. H. Mathews and W. E. Cockfield. The writer examined several thin sections supplied by Cockfield. (62) extending NNW from Copper Creek station, on the north shore of Kamloops Lake. This was o r i g i n a l l y mapped as Coldwater by Dawson (31), but he wisely stated that many of the areas of conglomerate so mapped may be Cretaceous. Another area l i e s f i v e to twelve miles south of Kamloops Lake on either sid£ of and south of Durand Creek, another l i e s ten miles south of that, and a fourth of twenty square miles, extends northwesterly from Nicola. Lithology; The Copper Creek area i s l i t h o l o g i c a l l y the most interesting. Most of the section here i s massive conglomerate. Pebbles i n i t are poorly rounded and sorted. They are composed of chert, f e l s i t i c volcanics, sl a t e , and minor amount of granite. The matrix i s a medium-grained arkose with a high proportion of rock grains. Neither matrix nor the conglomerate i t s e l f show the degree of induration that characterizes the A l l i s o n . There are sandstones and shales Interbedded with the massive conglom-erate beds. Overlying the conglomerate, apparently conformably, is a series of ultrabasic flows interbe.dded with e l a s t i c s which were derived from them. One specimen of the flow rock was found to have an o r i g i n a l composition of 45$ ol i v i n e and 20% pyroxene in large c r y s t a l s , and 35$ of a matrix which was o r i g i n a l l y fine pyroxene. The rock i s therefore classed as p i c r i t e , though no feldspar or feldspathoid was noted. The olivines range up to 2 x 3 mm. size. They are now entirely masses of fibrous ser-pentine with magnetite segregated i n cracks and around borders. Some retain the o l i v i n e shape, others are rounded. The pyroxenes are smaller, subhedral, and r e l a t i v e l y unaltered. They are (63) pigeonite and augite. The matrix i s now a mass of soft talc and serpentine. Other specimens of the p i c r i t e show a matrix of fine pyroxene crystals. A specimen ty p i c a l of the interbedded elas t i c s i s , in hand specimen,ia reddish-purple sandstone, f a i n t l y showing bedding. Under the microscope, only 55% of the rock is in d i s t i n c t grains. These are 0.1 mm. in size and larger, and are augite (some pigeonite). The remainder of the rock i s fine-grained serpentine, opaque clay minerals, iron oxides, auth-igenic quartz, and c a l c i t e . Much of the serpentine is in irregular aggregates of fibres surrounded by magnetite, and occasionally rhombic i n outlines. These were o r i g i n a l l y olivine c r y s t a l s , serpentinized i n the o r i g i n a l rock, eroded, and depos-ited as misshapen masses. There is nothing to Indicate pyro- ' c l a s t i c o r i g i n . The rock i s a graywacke drived from the ultra-basic flows, with l i t t l e transportation and opportunity for decomposition and contamination with other materials. Outcrops of rock similar in composition to the p i c r i t e described, but d i f f e r i n g i n kind and degree of a l t e r a t i o n , occur in several places east of Copper Creek, One area of a few square miles l i e s ten miles east. These areas are windows i n the Tertiary lava cover, and suggest a large underlying area of p i c r i t e . The conglomerate south of Kamloops Lake i s often very coarse. Blocks ten feet i n diameter have been found. The area near jJicola contains massive beds of medium arkose having only 15% quarts, much orthoclase, plagioclase, and rocks, i n a small proportion of limonite-sericite matrix. (64) Structure: The p i c r i t e s and interbedded graywackes are in apparent conformity with the underlying conglomerate. Attitudes in the conglomerate are dominantly NNW, p a r a l l e l to the trend of the area, with moderate dips northeast. The appearance of the p i c r i t e many miles to the east, and the absence of the conglomerate, suggests that the former i s a continuous formation, while the l a t t e r thins out eastward. In the area south of the Lake, the structure i s sync l i n a l , with strikes north-south and dips steepening toward the axis of the syncline. The central part of the syncline i s overlain by greenstones with unknown relations. The relations with the underlying Nicola Series are not de f i n i t e l y established. Folding as a rule i s more intense in the Nicola than in the Cretaceous rocks here, but the attitudes in the Copper Creek area are markedly accordant i n the two series. I t i s believed that there may be only a disconformity. The over-lying Oligocene volcanics are markedly unconformable. Age and, Corellation: For the age /there i s nothing more definite known than post-Triassic and pre-Oligocene. The nearest com-parable strata are those at Ashcroft. These, and also the Fraser River Series at L i l l o o e t , contain diabase ' t u f f s ' (see p.66 which suggests conditions and provenance similar to those of the Copper Creek picrite-graywacke. On the basis of the association of volcanism and sedimentation, a correlation with the Spence's Bridge volcanics may be made, but there i s l i t t l e else to compare i n the two. (65) CONTINUATION OF THE DEWDNEY-PASAYTEN TO THE NORTH-WEST Fraser River Series, The name was given by Dawson to the narrow belt of sedimentary rocks which follows the Fraser valley very closely from L i l l o o e t to Keefers. No very definite age determinations have been made on them, and i t is probable that several d i f f -erent series may be represented, since the belt crosses the general trend of the Cretaceous formations at a sli g h t angle. Distribution: East of L i l l o o e t the belt is about six miles wide, covering the loop i n the Fraser River between L i l l o o e t and Glen Fraser. Fountain Ridge, extending up to 6000 feet, is composed of these rocks. The belt extends NNW i n a widening b e l t , the west contact against older Paleozoic rocks, the east contact against overlying Tertiary volcanics. I t i s probably continuous with the Eldorado rocks'" mapped along the Yalakom River and at the head of Churn Creek. (see p. 68). Southward the belt narrows down to a l i t t l e over a mile, halfway between L i l l o o e t and Lytton. I t then widens to two miles, preserving t this width and closely following the west side of the ri v e r as far as Lytton. Below Lytton i t gradually swings across the r i v e r , leaving i t . e n t i r e l y at Keefers to follow a widening course to the SSE. I t presumably connects with the Ladner Slates and the Cretaceous rocks i n Coquihalla area, but has not been traced continuously. There i s a small separated area i n Botanle valley,aaffew miles east of Lytton. (66) Lithology: No complete sections have been obtained. The t o t a l thickness of strata near L i l l o o e t must be at least 7000 feet. Dawson (26) estimated at least 5000 feet east of Boston Bar. Coarse elast i c s predominate, and the sandstones are always feldspathic and occasionally pyroxenic 'diabase t u f f s ' . A r g i l l i t e i s more common i n the lower part of the sections, sandstone and conglomerate i n the upper. The conglomerate is coarse and highly indurated. Boulders are well-rounded, and include cherty quartzite, plutonics, porphyrites, etc. Limestone fragments are scarce, i n contrast to the conglomerate in the Eldorado. On Jackass Mtn., a p a r t i a l section shows 300 feet of arkose with plant remains, then 500 feet of T3»."Lack shale with marine s h e l l s , followed by 2000 feet of conglomerate. There is here a general resemblance to the upper part of the Hampton Creek and the Allison•along the Similkameen. (see p. 23-4) Structure: Fountain Ridge is a simple syncline. Low dips prevail north of the Fraser River. East of Boston Bar (26, p.107b) the strata form a t i g h t l y folded syncline s t r i k i n g N 40° W. A l l down the Fraser valley the strikes are p a r a l l e l to the general direction of the valley (N 20° W). Faulting p a r a l l e l to the valley i s indicated i n the shattering of the beds near Stein Creek and at Texas Creek. The Botanie Creek area shows strong f a u l t i n g against the granodiorite on the east. The persistence of such a narrow belt i s no doubt due to a combination of down-folding and f a u l t i n g ; the same structures that have l i k e l y controlled the course of the r i v e r . (67) In the northern part of the belt the rocks are unconform-able on Paleozoic rocks on the west side and unconformably overlain by Tertiary volcanics on the east. Wear Boston Bar they are unconformable (?) (see p. 18) on the Boston Bar A r g i l l i t e s of lower Mesozoic age. Most of the contact is with intrusives. Some of the intrusives near L i l l o o e t , and possibly others, are younger. The majority on the west are apparently older. Age: F o s s i l plants from near Stein Creek indicated Dakota age (Latest Lower Cretaceous). Probably as great an age range is represented in the various sections as there is in. the Dewdney-Pasayten Succession. The Eldorado Series General; The name i s given to a group of Lower Cretaceous rocks f i r s t described at Eldorado Creek i n the Bridge River Area (5). Further exploration by Drysdale (38) extended the area westward. Drysdale, however, included part of what i s now the Cadwallader Series with the Eldorado. McCann (66) completed the mapping of the area i n 1920, and put part of Drysdale's Eldorado into the Cadwallader, This series was found to be Upper Triassic i n age but i t s relations to the Eldorado were l e f t i n some doubt, as a conformable r e l a t i o n i s suggested i n some cases (see also p. 72) MacKenxie (59) extended the series to the north and west. Dolmage (35) In 1928 mapped the area between Gun Lake and Taseko Lake. He showed that Eldorado Series extended from Jurassic to Lower Cretaceous, and mapped a large area of Cretaceous volcanic which seemed to overlie the Eldorado conformably (see p. 73). (68) Distribution; I t appears that the Fraser River Series south of L i l l o o e t forms a northwest trending belt just east of Yalakom River. This belt i s found in the northwest corner of the Bridge River map-area and apparently joins with the Eldorado as mapped by Mackenzie at the head of Churn Creek. The older series thus extends as an a n t i c l i n a l tongue up to the head of Churn Creek. West of the tongue the Eldorado extends south irreg u l a r l y to within a few miles of Bridge River. Further west the area is cut off by the Coast Range intrusives along Gun Creek. North of Trigger Lake the later Cretaceous volcanics overlie the Eldorado. To the north around the Headwaters of Big Creek, both the older and younger Cretaceous rocks are overlain unconformably by the almost f l a t - l y i n g Tertiary lavas. Lithology; The series i s composed of a great variety of strat-i f i e d rocks. Most of i t is normal marine e l a s t i c s , a r g i l l i t e predominating. There are also limestones, g r i t s , conglomerates, volcanic agglomerate, and doubtfully flows. The thickness of the series i s given as ten to twenty thousand feet. The twenty is the most recent estimate of Dolmage (35, p. 82A). No complete section has been obtained yet. Dolmage divides the series into an upper and a lower zone, each composed mainly of a r g i l l i t e with fine sandstone, and a middle zone containing a l l the conglomerate, limestone and vol -canics of the series as well as a r g i l l i t e . Marine f o s s i l s are found i n a l l three gones. Thick Aucella beds occur i n the upper sandy layers. MacKenzie reports a 500 foot formation consisting mainly of sandstone, exposed on Relay Creek. McCann and Bateman also report considerable sandstone, some of which i s coarse, (69) feldspathic and indurated, and forms beds forty feet thick, McGann also reports intercalated flows of andesite at certain horizons. . ' The conglomerates are generally of coarse cobble size. The cobbles are well-rounded and composed of chert, quartzite, limestone, a r g i l l i t e and volcanic material in an arkosic matrix. Large angular fragments of limestone and a r g i l l i t e are invariably present with the rounded cobbles, and sometimes make up the whole bed. In some cases the limestones are i n slabs three feet sauare by a foot thick with no sign of rounding. MacKenzie explains them as due to the contemporaneous erosion of imcompletely con-solidated st rata of the same formation. They are evidently similar to the shale-breccia i n the Pasayten series (see p. 31). Plutonics are not mentioned' i n any of the conglomerates except i n one. doubtful case by McGann (67). Structure; There i s apparently no unconformity within the series mapped, although the limestone conglomerate i n d i r e c t l y suggests intraformational erosion, and possibly diastrophic movement affect-ing the basin during sedimentation. The d i s t r i b u t i o n suggests a major a n t i c l i n a l structure along the l i n e of the Shulaps mountains. In general, folding increases i n intensity toward the west. Here beds are v e r t i c a l over large areas, but around the head of Dash and Relay creeks, folds are open and dips generally less than 40°. MacKensie describes close folds along Gun Creek s t r i k i n g nearly north and south. McCann gives NW-SE axes for folds further south. Dolmage indicates a large a n t i c l i n a l structure, on the basis of the d i s t r i b u t i o n of the conglomerate (70) zone, s t r i k i n g and plunging steeply west from Castle Mountain. The strata strike obliquely into the batholithic rocks. These are cle a r l y intrusive, and the date of intrusion was post-folding. Several small stocks of granitic to d i o r i t i c compos-i t i o n occur well within the area of the Eldorado. In the west and north the Eldorado strata pass with apparent conformity under the Cretaceous volcanic series. At some loc-a l i t i e s there i s much deformation i n the sediments against the volcanics, and the relations are not so clear. On the north and east flows of Miocene basalt overlie the Eldorado unconformably. Near the head of French Bar Creek, sedimentary strata of probable Coldwater c o r e l l a t i o n overlie the Eldorado unconformably. The date of folding thus appears to be post-the lower part of Upper Cretaceous and pre-Early Tertiary. Conditions of Deposition: There i s some p a r a l l e l with the Dewdney-Pasayten. Both indicate marine deposition interrupted by volcanism. However nothing corresponding to the upper part of the Pasayten i s present here. Erosion and deposition were milder. There was simultaneous erosion and deposition, and perhaps minor diastrophism during the formation of the series. I t i s a matter of some speculation whether the feldspathic sandstone layers were formed from volcanic rocks, since other evidence indicates that g r a n i t i c rocks were absent from the source areas. Age: Bateman found f o s s i l s i n the Eldorado Series which were determined as Lower Cretaceous. His c o l l e c t i o n included Aucella p i o c h i i Gabb, now considered to be Upper Jurassic i n Ca l i f o r n i a .(Anderson, 2). (71) Dolmage found f o s s i l s i n a number of l o c a l i t i e s , and was able to show that the strata above the conglomerate zone are Upper Knoxville (lowest Cretaceous) and those below i t are Lower Khoxville (Upper Jurassic). Representatives of the Eldorado Series WW of Chilko Lake. General; Large areas of Lower Cretaceous rocks have been mapped by Dolmage (35, 34) sixty to 120 miles northwest of the Bridge River area. Their age i s de f i n i t e and they are l o g i c a l l y corr-elated with the Eldorado. However their stratigraphy has not been worked out i n the same d e t a i l , so they w i l l be discussed separately. Distribution; A large area surrounds the northern t h i r d of Chilko Lake, and extends north to Choelquoit Lake, and west a l i t t l e beyond Tatlyoko Lake. On the east the boundary i s i r r -egular from Mt. Tatlow to Choelquoit Lake, where the rocks are overlain by s u p e r f i c i a l lavas and d r i f t and doubtless extend farther northeast. Another area of about 80 square miles l i e s north of Razorback mountain, and an area of similar size l i e s north of Perkins peak. In a l l areas and p a r t i c u l a r l y the Perkins peals area, the extent i s reduced by intrusions. The d i s t r i b -ution is thus a broken-up belt trending N 50° W on the northeast flank of the Coast Range. Lithology: The Perkins area contains thin-bedded sandstone, black a r g i l l i t e , and ''considerable volcanics. The Ragorback area i s mainly dark-brown sandstone, conglomerate and shale, with no volcanics. Around Chilko Lake thick massive beds of coarse, cross-bedded arkose form the upper part of the formation and are most extensive. Sandstone, shale, and thin conglomerates make (72) up the balance of the section. The arkoses have fresh angular plagioclase, augite, and volcanic fragments, and much resemble t u f f s . Dolmage (33) found no plutonic pebbles i n the conglomer-ate, and considers that plutonics were absent from the source, of the sediments. Structural Relations; Strikes and dips are very variable asaa manifestation of plunging folds. There i s l i t t l e general trend in evidence. The area -between Chilko and Tatlyoko Lakes has low dips, but inclinations elsewhere are high, and p a r t i c u l a r l y so near contact with the older rocks. Wherever contact dips are moderate, the Triassic and the Cretaceous appear to be almost conformable. The Chilko Lake area Is cut off i n the north by 'Quartz-d i o r i t e stocks. Larger stocks have intruded the areas to the north. There i s l i t t l e metamorbhism and no d i s t o r t i o n of the bedding. Age; Fossils from the upper horizons around Chilko Lake estab-l i s h the age as Lower Cretaceous. The Species Aucella crassic-o l l i s Keyserling i s common. This Is in the lowest Cretaceous of the Shasta (2). From the northern area an ammonite gives r the age very sha^p^ly i n the Valanginian. Upper Cretaceous Volcanics of Gun Creek Area Distribution; Late Lower or Early Upper Cretaceous rocks are mapped by Dolmage (35) between and north of Gun Creek and Taseko River. They are bounded i r r e g u l a r l y on the south by the intrusives of the Coast Range, on the east by the Eldorado Series and on the north partly by post-Eocene lavas. On the west the boundary with the Triassic volcanics of Chilko Lake Area is not mapped. (73) Lithology; The series may have a t o t a l thickness of 10,000 feet. The rocks are explosive breccias and thick flows, both of andesite or basalt composition. They are very fresh. Conglomerate of well rounded and s t r a t i f i e d volcanic fragments occur i n t h e southern part of the area. S t r a t i f i e d argillaceous or tuffaceous sediments containing abundant plant remains are found i n the lower part of the formation. Structure: Folding i s described as s l i g h t . The rocks are i n -truded by the Coast Range Intrusives. The contact relations with the Eldorado have been discussed. However, from the areal d i s t r i b u t i o n of the series, and the way i n which i t crosses the conglomerate zone of the Eldorado series at right angles, i t seems l i k e l y that the r e l a t i o n is broadly unconformable. Age; Plant f o s s i l s from several l o c a l i t i e s i n the lower strata give the age as Late Lower or Early Upper Cretaceous. CRETACEOUS OF THE NORTHERN AREAS The Hazelton Series Large areas north of 53rd p a r e l l e l on the east flank of the Coast Range are underlain by a complex group of volcanic and sedimentary rocks largely of Jurassic age. These were named the Porphyrite Series by Dawson (26) because of the abundance of porphyritic lavas i n them. He considered them to range i n age from Jurassic to Lower Cretaceous. The rocks were explored along the Skeena River by Leech i n 1909 and re-named the Hazelton Series. (74) L i t h o l o g i c a l l y they consist of some 10,000 feet of strata. Sections vary i n different l o c a l i t i e s , and there i s no complete section available. Volcanics of andesitic character predominate. Bedded t u f f s , sandstone, conglomerate, a r g i l l i t e , and some lime-stone make up the remainder. Around Eutsxik Lake (9) and east of here, and at Owen Lake, flows predominate. Along the Skeena River, well bedded tuffs predominate. In the Eymoetz River Area (49), Hanson estimates that there are 10,000 feet of strata. He makes four divisions:-(1) Upper Sandstone - 1000 feet of marine a r g i l l i t e , quartzite, conglomerate and a l i t t l e coal. (2) Upper volcanic - t u f f s , breccia, and water-sorted frag-mentals. (3) Middle sedimentary - thin bedded a r g i l l i t e and quartzite. (4) Lower volcanic - andesite flows, tuff and breccia. There is thus a general correspondence in l i t h o l o g i c a l succession to the Yakoun formation on Queen Charlotte Islands. Folding is generally close. Strikes are generally north-west, but i n the western part of the area they seem to be governed by the shape of the intrusive bodies. East-west to northeast strikes predominate in the *2ymq^ _etz area, east of Kitsumgallum, and along the Skeena River from Terrace to Hazelton. The age of the middle sedimentary member of the Zymoetz area i s well-defined i n Lower Middle Jurassic. In other areas the age has simply been given to be 'probably Jurassic, possibly Cretaceous e t c ' I t i s not impossible that other areas may extend higher and possibly to the Cretaceous, (75) Skeena Formation Overlying the Hagelton Series are small l o c a l areas of less Indurated and less folded sediments carrying a few coal seams of economic importance. These have been called the Skeena formation. The age has been given as lowest Cretaceous on plant evidence. Distribution: Separate basins of the Skeena formation are widely scattered over the larger areas of Hazelton Series. Several small areas occur south and west of Telkwa. There is an area of 30 square miles and several smaller ones north of McDowell Lake at the head of Zymoetz,River, others between Morice town and Hazelton in the Bulkley Valley, north of Kitsumgallum Lake, an the Skeena near Kispiox, and further north a large area in the Groundhog basin. Along the Skeena near Cedarvale there may also be a small basin. I t occurs charac-t e r i s t i c a l l y i n valleys, and is always surrounded by Hazelton Rocks. Lithology; The rocks are shales, feldspathic sandstones and conglomerates, with coal. They are l i t t l e indurated. The con-glomerates are largely of chert and quartzite. Plutonics are not mentioned. The formation i s apparently not much over a thousand feet thick. Structural Relations: The relations with the Hazelton Series are s t i l l a l i t t l e doubtful. Alongr'.the Bulkley, McConnel thought the two were conformable or nearly so (55,57). From Hazelton to the Groundhog area Malloch (62) likewise found them conform-able, and made the d i v i s i o n a r b i t r a r i l y . Near Cedarvale, Kindle (52) found strata containing coal and Lower Cretaceous f o s s i l s i n apparent conformity with the Hazelton Series. In the (76) Kitsumgallum area, Hanson assumed them to be unconformable on the basis of the smaller amount of folding in the Skeena. In the JSymoetz area (49) he found good evidence of unconformity in the overlapping of the Skeena onto the different members of the Hazelton. Folding is less intense than i n the Hazelton Series. Induration i s also much less. The Coast Range intrusives cut the Hazelton Series extensively, but only a few granite, alaskite and lamprophyre dikes cut the Skeena, i n the Kitsumgallum and Zymoetz areas. The absence of plutonic fragments in the Skeena conglomerates suggests that they were formed not much l a t e r , i f not before the intrusives came. Age; F o s s i l plants obtained by Leach along the Bulkley indicate an age equivalent to Kootenay or lowest Cretaceous. Kindle's f o s s i l s from Cedarvale give the age as Lower Blairmore, or somewhat younger. Marine f o s s i l s from the ZymOetz area are Cretaceous. Upper Cretaceous i n Owen Lake Area (54). A series of sediments of post-Lower Cretaceous age is mapped i n a small area around Owen Lake, f i f t e e n miles northwest of the west end of Francois Lake. The rocks are a r g i l l i t e -often carbonaceous-, graywacke, and conglomerate. The upper half i s c h i e f l y massive tuffaceous graywacke, the lower half i s inter-bedded a r g i l l i t e , graywacke-quartzite and conglomerate. The graywacke i s medium-grained, dark gray, massive and indurated. I t contains a high proportion of rounded andesite grains. Lang does not say whether the material was eroded from older rocks or i s of direct volcanic o r i g i n . The upper beds seem to be (77) water-deposited tuffs contaminated with arkose. The thickness is estimated to be 4000 feet. The accordance of dips i n the Cretaceous and the Jurassic (Hazelton) rocks suggests absence of angular unconformity be-tween' them. The structure is a homocline dipping 20° west. The sediments occur up to a high elevation. A small stock of hornblende granite i s intrusive into the sediments. The age was given by a f o s s i l plants determined by B e l l . He was unable to form a positive conclusion other than post-Lower Cretaceous, but one species suggested basal Upper Cretaceous. , Upper Cretaceous or Younger i n Fort Fraser Area. A formation of andesitic lavas with intercalated conglo-merate and graywacke of post-Lower Cretaceous age is found forty.miles east of the Owen Lake Area. They are mapped over an area of one hundred square miles' between Francois Lake and Endako River. Common i n the conglomerate are pebbles of pink granite which, along with other types of plutonics are apparently pre-Hazelton i n age. Granites were also noted i n conglomerates of the Hazelton along the Bulkley north of Telkwa (McConnel, 67). The formation dips 45° southwest here. I t i s overlain by folded Eocene or Oligocene lavas. These i n turn are overlain by almost f l a t - l y i n g flows. The re l a t i o n between the Eocene-Oligocene strata and the Cretaceous is not stated, but both together are described as being only s l i g h t l y deformed compared with the older rocks (Hazelton). This would indicate a pre-Upper Cretaceous folding, and no more t i l l mid-Tertiary. (78) . CRETACEOUS ROCKS, OF THE QUEEN CHARLOTTE ISLANDS General; Marine and estuarine deposits of Upper Cretaceous age have a limited areal d i s t r i b u t i o n but important s t r a t i -graphic extension on Graham Island. These rocks are l i t h o -l o g i c a l l y and structurally very similar to those of the Nanaimo Series, and rest unconformably on rocks of Jurassic age. These i n turn are similar to and are correlated with the Vancouver Group on Vancouver Island 1. The Graham Island section i s s l i g h t l y older than the Nanaimo section, though s t i l l largely, i f not e n t i r e l y , i n the Upper Cretaceous. Early work by Richardson (80) i n 1872, was c h i e f l y re-connaisance, with some d e t a i l i n the Jurassic and Cretaceous around Skidegate I n l e t . Further work was done by Dawson' (28) i n 1878, and by E l l s (41) i n 1906. Dawson's map and table of formations were accepted u n t i l 1912. Clapp (20) and MacKenzie (59) then showed that'the two lower divisions of Dawson's Cretaceous section were Jurassic, and were separated from the remaining Cretaceous by a strong unconformity. MacKenzie's Memoir summarizes a l l the previous work, and gives a f a i r l y complete description of the Cretaceous rocks. The name "Queen Charlotte Series" i s retained for the Cretaceous section. D i s t r i b u t i o n ; The Cretaceous rocks form an i l l - d e f i n e d and broken basin extending i n a NNW direction from Maude Island i n Skidegate Inlet. ' Two s t r i p s , each two to three miles wide, appear to extend SE into Moresby Island,' from points on the sou shore of Skidegate Inlet f i v e and f i f t e e n miles west of Spit Point. The area north of the i n l e t i s partly overlain by Late r;l.,; This correlation i s made by MacKenzie (59). The Queen Charlotte rocks are however, mostly younger than the Vancouver and more comparable to the Hazelton Series. ( 7 9 ) Tertiary lavas. Other disconnected areas along the same trend may be present under the extensive lava cover to the north. Stratigraphy: The table of formation i n the area is b r i e f l y as follows: Late Tertiary Masset volcanics Skonon sediments Eocene Etheline intrusives Upper Cretaceous Queen Charlotte Series: 8000 f t . seds Skidegate fmn. ss. sh. 2000 Honna cpng., ss. 2000 Haida ss., sh., coal. 4000: Upper Jurassic Kano and Langara, quartz-diorite i n t r Middle Jurassic Vancouver Group - vole, and sed. General Lithology: The succession i s dominated by coarse e l a s t i c s . The lower Haida Formation shows a progression from coarse g r i t t y arkoslc'sandstones, through normal sandstones to shales. The Honna formation begins with a coarse conglomerate; this i s followed by shale and sandstone, then a thick conglomy erate of more moderate grade. The progression i n the Skidegate formation i s about the same as i n the Haida. In general, there is rapid variation i n both v e r t i c a l and horizontal directions. This, along with the predominance of impure e l a s t i c s , and pres-ence of conglomerate, indicates a s i m i l a r i t y i n conditions of orig i n to the Nanaimo Series. Haida Formation; The formation i s largely sandstone, with inor amounts of shale increasing toward the top, and l o c a l conglomerate and breccia at the base. There is no persistent conglomerate at the base. Basal beds are usually, but not m (80) entirely coarse arkose, often with a high enough proportion of volcanic rock fragments to simulate t u f f s . The arkose i s t y p i c a l l y medium to coarse, with auartz about 40% and almost as much plagioclase, some of which i s as basic'as labradorite, yet fresh and angular. Rock fragments are also common. The matrix is green-colored and high i n c h l o r i t e . Some of the finer massive beds are r e l a t i v e l y pure quartz sandstone. The .Robertson coal :, seam occurs near the middle of the section. False bedding i s common, pa r t i c u l a r l y i n the arkoses. The formation varies in thickness from 2000 to 5500 feet, mainly because of an i r r e g -ular surface of deposition. Honna Formation; The formation i s largely conglomerate. There is a six-foot bed of very coarse conglomerate at the base with boulders up to three feet, and averaging over six inches in diameter. Less coarse conglomerate makes up the lower few hun-dred feet of the formation, and this i s followed by a thousand feet or more of shale and crossbedded sandstone. The upper f i v e hundred feet i s again conglomerate. Typical conglomerate is composed ch i e f l y of well rounded d i o r i t e boulders and cobbles. Some of the boulders are traceable to the Maude 'Formation. Total thickness of the formation is about 2000"feet. : Skidegate Formation; This formation grades from a coarse crossbedded g r i t t y arkose through f i n e r sandstone to black car-bonaceous shale. I t has a minimum thickness of 2000 feet. Structure; The series rests unconformably on the Jurassic formations, alternately on the Maude formation and on the Yakoun. The Kano and Langara Quartz-diorite bodies cut the Jurassic rocks and are supposed to be older than the Cretaceous. The (81) surface of deposition is irregular i n d e t a i l , and had consid-erable r e l i e f , as evidenced i n the varying thickness of the Haida formation. South of Yakoun Lake the Cretaceous is overlain uncon-formably by r e l a t i v e l y f l a t - l y i n g flows and agglomerates of Late Tertiary age. The strata are folded into several synclinal basins com-plicated by minor folds which are more intense on the western limbs.. Tight folding, overturning, and f a u l t i n g i n the west are attributed to thrusting against the r e l a t i v e l y immobile underlying volcanics, as was the case with the Nanaimo series. The outline of the basin conforms to the trend of the Jurassic rocks, which i s N 30° W. The general trend of the folds i n the basin i s more nearly N-S. Large numbers of dikes, s i l l s and small laccoliths cut the Cretaceous rocks as well as the Jurassic rocks. These i n -trusives have a range In composition from dacite to basalt, with andesite predominating. Time of Folding; Since the next youngest dated strata are Miocene, and these are unconformable on the Cretaceous, the per-iod of folding may have been anywhere between Upper Cretaceous and Miocene. The intrusive Etheline formation is also pre-Miocene, and with some logic i t may be corellated with the Metenosin Volcanics on the south end of Vancouver Island, which are known to be Upper Eocene. Many of these dikes were intruded into the Cretaceous sediments before the folding took place, so the date of the folding, l i k e that of the Nanaimo Series would then be Oligocene. (32) * Conditions of Deposition; The lower part of the Haida was deposited i n l o c a l basins or estuaries, giving i t a variable thickness. The Robertson coal seam is continuous, and rep-resents a uniformity of surface and conditions over.a large part of the basin. From then on sedimentation was more or less continuous over the basin. It was marine, near shore, and per i o d i c a l l y very rapid, with r e l a t i v e l y long ouiet periods The predominance of coarse g r i t t y arkose i s evidence of rapid erosion and deposition. The much thinner shale beds probably took more time to accumulate than -the "thick arkose beds. The heavy conglomerates of d i o r i t e i n the Honna formation may have had their o r i g i n i n land now downwarped beneath the sea. There are only a few areas of quartz-diorite exposed on the Queen Charlotte Islands now, and the area would have been much less i n Upper Cretaceous. Possibly areas of quartz-d i o r i t e underlie the Tertiary volcanics, but no large mass is indicated. The large masses of plutonics of the Coast,Range are over 100 miles away. The same problem applies to the great thickness of arkose, which i s evidently the debris of inter-mediate plutonic rocks. Postulation of a source area on the immediate east or west i s almost a physical necessity. The narrow shelf and steep slope off the west coast are more sugg-estive of a sunken borderland than the shallow coastal trough the east. Age and Correlation; A few f o s s i l s have been found i n a l l three formations. The Haida formation has given the best collec tion. A l i s t of species is given by MacKenzie (59,pp. 65-66). They were determined by T. W. Stanton who states that most of them are not older than Gault (basal Upper Cretaceous). One (83) , species from the highest part of the Skidegate formation suggests Turonian. According to Whiteaves (107), speaking of ea r l i e r collections,the fauna is d e f i n i t e l y older and different from the Nanaimo fauna. The Nanaimo i s of Senonian age. NANAIMO SERIES General: Marine and estuarine coal-bearing strata of Upper Cretaceous age form a well"defined belt along the east coast of Vancouver Island. The lower f o s s i l i f e r o u s members of this series were given the name 'Nanaimo Group' by Dawson (30). Glapp (19) used the name 'Nanaimo Series' for the entire conformable suc-cession of some ten thousand feet i n the v i c i n i t y of Nanaimo. Richardson (81) made the f i r s t extensive examination of the deposits. He reported extensively on the coal measures and made good f o s s i l c o l l e c t i o n s , establishing the Late Cretaceous age of the Series. Further work on the Series has been done princ-i p a l l y by Clapp (18, 19, 21), and by J. D. MacKenzie (62, 61). Distribution: The accompanying map (No. 3) shows the d i s t r i -bution of rocks correlated with the Nanaimo Series. The largest area i s that extending from Campbell River to Nanoose Bay along the east coast, with an irregular western boundary from two to ten miles inland and considerably widened southwest of Campbell River. Denman and Hornby Islands and the drift-covered area northeast of Courtenay are no doubt underlain by these rocks. Outliers of this basin are found on Texada and Lasqueti Islands and near Mt. Albert Edward. The best known area is that extending southeast from Nanaimo on the mainland and onto the adjacent Gulf Islands. (84) A basin of similar dimensions centers around Duncan, and ex-tends oarms to the WWW, the southern of which extends as far as the west of Cowichan Lake. There is no continuation to the SE. Small areas are found on San Juan and Orcas Islands, but none on the Washington mainland, (M4). ... A separate area extends twenty-five miles northwest and ten southeast from Port Albernl. Another small area some twenty by s i x miles i n extent occurs on the HE coast of the Island at Suquash, and probably underlies Malcolm Island. Numerous small detached areas are apt to turn up i n unexpected places. A l l areas are c h a r a c t e r i s t i c a l l y low-lying, generally less than 1500 feet above sea l e v e l , and have subdued topography, contrasting sharply with the adjacent older rocks. One area of basal conglomerate reaches 3000 feet on the south side of Coronation Mountain, near Duncan. The small outliers near Mt. Albert Edward extend to over 4000 feet . Stratigraphy; The most comprehensive and best described section of^series comes from the Nanaimo Map-Area (Clapp 19). Here eleven formations are mapped and described. These and the cor-related formations i n the other areas of the Island are shown in the table on P. 85. The Cowichan basin lacks the East Wellington Sandstone and coal, and the three top formations of the Nanaimo basin. The coal seams are also absent from the-Newcastle formation, so the remaining strata are included with the Cranberry to form the Ganges formation. This, along with the Protection, Cedar D i s t r i c t , and De Courcey formations are H. C. Gunning, personal communication. (85) Formations of the TIanalmo S e r i e s Nanaimo Basin . Cowichan Basin Gumberland Area A l b e r n i Area G a b r i o l a , ss, sh. - 1400' (SI Galiano Id. - 3000' Northumberland, oong, ss, sh. - 1100' (So. Galiano Id:-sh. - 500' ss, eg. - 2000' sh. - 200' De Courcey, ss. - 900' Cedar D i s t r i c t , sh. - 750' P r o t e c t i o n , sandy sh.- 650' Newcastle, g r i t , sh., c o a l - 175' Ganges fmn.(Prot. & Hew.) ( S a l t s p r i n g Id. - 750 Extension, eg, sh, ss, Wellington ooal - 600' East Wellington, ss.- 35' Haslam, sh. — 600' Benson, eg. 0 to 100 (absent)' (absent) (absent) Dunoan, ss, sh. - plus Extension oong. , (absent) J 2500' 800'. G Upper Conglomerate F Upper shale E Middle conglomerate D Middle shale C Lower oong. B Trent River, shale A . Comox, ss, sh, g r i t , cong, co a l . 330' 800' 1100' 100' 900' 1000' 750 Haslam, Benson, shale. - 1000' shy-ss. - 3001 arkose. - 300' cong. 0 to 750, Shale 1800' Sandstone, arkose ,-var. Cong, arkose, - 300' (86) mapped as the Duncan the Cowichan basin. In the Cumberland Area, (81, 61), the Comox Sandstone, carrying the principle coal seams,of the area near i t s base, is correlated with the Protection and Newcastle formations. This correlation i s on the basis of the continuity of the coal horizon and on the s i m i l a r i t y of the overlying successions. The Trent River formation is thus comparable to the Cedar D i s t r i c t Shales. Richardson's divisions above this show further a general;..,similarity to the Nanaimo section. The presence of the coal seams alone i s obviously a weak basis of correlation, since at the same horizon, coal was absent in the r e l a t i v e l y nearby Cowichan Basin. F o s s i l evidence adds nothing. The correlation therefore rests mainly on the s i m i l a r i t y of stratigraphy in the two areas. The Comox basal In the Cumberland Area. I f the above correlation i s correct, then the 2000 feet of under-lying;.; strata represented i n the Nanaimo basin are absent in the Cumberland Area. That i s , there i s an overlap of this magnitude between Nanaimo and Cumberland. f In the Alberni Area a thick shale member i s correlated with the Cedar D i s t r i c t Shales and the Trent River Shale, but there i s no evidence to support t h i s . There is no p o s s i b i l i t y of correlating the Suquash strata with a definite position i n the Nanaimo Section. Lithology -- General; The Series i s made up of formations of sandstone, conglomerate and shale. Limestone is absent except in one l o c a l case. The only volcanic material i s d e t r i t a l from consolidated strata. In the type section, 50$ of the rock i s (87) sandstone,.15% i s conglomerate, and 55% shales. The sand-stones are dominantly feldspathic; beds of coarse, g r i t t y arkose, with fresh orthoclase, plagioclase and l i t h i c fragments, are common throughout the section. Description of Formation: Benson - This i s a l o c a l basal conglomerate, absent i n some l o c a l i t i e s , up. to 700 feet thick in others. It occurs at various horizons i n the different l o c a l i t i e s . I t is absent as a rule i n the Cumberland Area, present as a rule i n the. Alberni Area, and l o c a l l y developed i n the other areas. I t varies con-siderably i n character,, in some cases being made up of a variety of rounded, transported boulders readily traceable to older Island formations, and i n other cases being an. angular breccia of l o c a l derivation. This i s common i n the Cumberland Area. The matriz of the conglomerate i s usually arkose, though i n a part of the Alberni Area MacKenzie (105) notes some very quartzose sandstones i n association with the conglomerate. Where the Benson conglomerate i s absent, arkose or other-wise impure, coarse, g r i t t y sandstone forms the base, though i n Cumberland Area, ordinary shale and bone coal are often basal. On Texada Island, McConnel (108) describes basal beds consisting of a few feet of red clay. In some cases these are bedded, in others simply gradational into the decomposed volcanics beneath. The normal conglomerate, here a hundred feet thick, overlies the clays. McConnel compares them to l a t e r i t e s (see P. 33, R69), In the Alberni Area, i t i s interesting that MacKenzie (105) finds within a few feet of the base of the Cretaceous, coarse greenish conglomerate alternating with l e n t i c u l a r beds of (88) purplish, maroon and claret coloured, coarse sandstone. Haslam Formation: This i s t y p i c a l l y a marine, f o s s i l i -ferous somewhat sandy, shale formation. In the Nanaimo Area i t is thin-bedded, sandy, and frequently carbonaceous, with thin sandstone beds becoming coarser and thicker toward the base. It averages.600 feet thick i n the Nanaimo Area, 1500 feet along the Chemainus River, and about 2500 feet east of Duncan. In each case a greater portion of the lower part is sandy. The upper sandstone interbeds are s i l i c e o u s , whereas the lower beds are arkoses of varying composition. East Wellington Font; In the Nanaimo Area the Ha slam form-ation grades into a persistent t h i r t y - f i v e foot bed of medium sandstone, which forms the fl o o r of the Wellington coal seam. .Wellington Coal Seam? This and the other coal seams of the Nanaimo c o a l f i e l d are described i n considerable d e t a i l by Clapp. I t i s s u f f i c i e n t to note here that despite the variab-i l i t y of the surrounding rocks, and of the thickness and quality of the coal, the horizon i s very persistent throughout the Nanaimo basin. However i t does not appear in the adjacent Cowichan basin. I t averages four to seven feet i n thickness. Extension Formation- This i s a thick conglomerate of f a i r l y constant thickness, averaging 600 feet i n the Nanaimo and 800 feet i n the Cowichan basin. I t is made up of uniform sub-rounded pebbles averaging less than one inch, composed of vein quartz, chert and resistant volcanics, set loosely in a matrix of feldspathic sand. In the Cowichan basin i t is thicker, coarser, and carries a greater variety of rock types.- Near Ladysmith, SE of Nanaimo and north of Cowichan basin, the (89) formation becomes largely siliceous sandtone. Crossbedding and cut and f i l l structure are common. Cranberry and Newcastle Formations- These two formations are similar, and are combined to form the Ganges formation i n the SE part of Nanaimo basin. They are made up of thin-bedded sandy shales grading upward to thicker feldspathic g r i t s and contain-ing two coal seams. The Cranberry i s 200 to 600 feet thick, averaging 250, i t s upper l i m i t being defined by the Lower Douglas coal seam. The Newcastle i s likewise variable, averages about 200 feet, and contains the main Douglas seam one th i r d the way up,, Both seams are absent i n the Cowichan basin, though the sandy shales are commonly carbonaceous. Protection Formation- In the Nanaimo Area this formation is a thick-bedded, grayish-white, fine to medium, g r i t t y felds-pathic sandstone. I t occasionally passes into pebbly beds, and near the top becomes shaly i n tra n s i t i o n to the Cedar D i s t r i c t formation. Clapp records quartz, orthoclase, plagioclase, b i o t i t e , epidote, and ch l o r i t e i n the g r i t s . The thickness i s uniformly about 650 feet. In the Cumberland Area, the Comox sandstone corresponds to the Protection and probably to. part of the Newcastle. I t is a light-coloured, medium-grained, thick-bedded sandstone. Five seams of coal with associated carbonaceous shales occur i n the lower 500 feet. The two important seams are within 100 feet of the base. A variable intra-formational boulder' conglomerate l o c a l l y replaces large sections of the sandstone and contained 1. I t i s not intraformational according to the d e f i n i t i o n of Twenhofel (93), but i t l i e s within (intra-) a formation and not between/(inter) two formations. (90) coal seams. From 60 to 600 feet of the formation may be thus replaced, showing cut and f i l l structure on a large scale. The thickness of the Comox varies from 80 to 1000 feet. The variation i s due chie f l y to the r e l i e f of the surface of deposition. The two lower coal seams are of good thickness and quality, but are e r r a t i c a l l y s p l i t up by partings of shale. As.horizons they are persistent, but due to their nearness to the base, and the uneven basal topography, they are frequently cut off by 'islands' of the older rock, and are valueless for some distance away from the islands. The i r r e g u l a r i t i e s of the coal are thus features of deposition, not of deformation as In the Nanaimo fields.. The variable thickness of sandstone, g r i t and 'red beds' near the base of the Alberni section may be equivalent to part of the Comox Sandstone. ' Cedar D i s t r i c t Formation- This formation i s uniformly fine sandy, carbonaceous and ferruginous shale, with minor beds of sandstone increasing toward the top. Its thickness i s about 800 feet in Nanaimo basin. The equivalent Trent River shales i n Cumberland are 1000 feet. The shales i n the Alberni Area are more massive and less sandy, and are at least 1200 feet In thickness. On French Creek, near P a r k s v i l l e , similar shales are 1800 feet thick. B§-Courcey Formation- In Nanaimo area the Cedar D i s t r i c t shales grade up into a formation of thick-bedded feldspathic g r i t s with pebble,y and occasionally boulder conglomerate. Its thickness i s about 900 feet. In Cumberland Area, d i v i s i o n C of Richardson (81), called the "Lower Conglomerate,' corresponds (91) to the De Coureey. I t is likewise composed of 900 feet of conglomerate and sandstone. In the Cowichan basin, the upper part of the series, equi-valent to the Ganges, Protection, Cedar D i s t r i c t , and part of the De Coureey are mapped together as the Duncan formation, at least 2500 feet thick. Northumberland Formation- This formation consists of sandstone and conglomerate bounded on the top and bottom by per-sistent sandy shale beds. The conglomerate has a great variety of well-rounded close-packed pebbles. The formation is about 1100 feet thick east of Nanaimo, at least 2000 feet on NW Salt-spring Island, and 2500 feet on south Galiano Island where the conglomerate member amounts to 1000 feet. The upper shales average 500 feet thick, the lower shales much less. Corresponding to this i n Cumberland Area are the D, E, and F divisions of Richardson. These are; D - Middle Shale--100' feet conglomerate; and F - Upper Shale--800 feet of shale. Gabriola Formation- The highest formation of the series i s dominantly medium-grained, g r i t t y , impure c h l o r i t i c sandstone. Thin sandy shales are common i n the upper 500 and i n the lower 100 feet. Crossbedding i s common. The formation has a thick-ness of 1400 feet. East of Nanaimo, and 3000 feet twenty miles to the southeast on Galiano Island. The G d i v i s i o n of Richardson, the 'Upper Conglomerate' -320 feet thick, may correspond to part of the Gabriola. Structural Relations Internal Structure: The formations are conformable through-out the series i n a l l basins. Cut and f i l l structure i s common (92) beneath the conglomerates. I t i s developed on a pa r t i c u l a r l y large scale in the Cumberland Area, where cuts of f i f t y to one hundred feet have been noted, and t o t a l cut and f i l l must amount to several hundred feet. However, there is no evidence for a widespread disconformity. Folding i s generally mild but l o c a l l y intense. The major structure of the east coast areas i s a broad, gentle, NW trend-ing - syncline in Georgia S t r a i t . Most of the areas are on the west limb so.that dips are predominantly northeast. The only exposTires on the east limb are those at G i l l i e s Bay, 'Large and small scale folds are superposed on this major structure. Large scale folding i s best developed in the southeast:, portion of the Nanaimo basin. Two prominent anticlines and intervening synclines trend NW - SE along the l i n e of the Islands east of Chemainus. Their limbs dip 15° to 30°, and occasionally 60° or more. Some four to six thousand feet of strata are involved. These folds die out to the northwest, so that near Nanaimo only small, l o c a l l y intense, folds involving minor thick-ness of strata occur along the margins of the area. In Cumberland Area the beds dip at 5° to 10° northeast. There are only a few l o c a l folds, and no strong f a u l t s . The structure i n the Alberni Area is a syncline with minor folds and complicated by a major an t i c l i n e which i s faulted apparently, normally with the, northeast side down^hrown. There is considerable divergence of s t r i k e s , the average being N 45° W. Such minor 'wrinkles' are common in the Cedar D i s t r i c t and Haslam shales; p a r t i c u l a r l y where the l a t t e r formation i s crumbled against the base by overlying massive beds. They are unpersis-tent, generally open and of small amplitude. (93) Sharp, r o l l s , l o c a l l y called f a u l t s , are common where deformation may be s l i g h t , and even i n strong massive beds. Clapp (19, p. 74) attributes them to pre-consolidation movements. In the Nanaimo basin there are four large f a u l t s , and numerous small ones, most of which are r o l l s . Two of these larger faults l i e near the crests of small anticlines and trend o approximately p a r a l l e l to them (N 35 W). They are reverse f a u l t s . They dip steeply southwest and the southwest side is upthrown a few hundred feet. The other two are problematical, but of the same structural magnitude. The Cowichan basin contains two major synclines trending N 70° W and s l i g h t l y overturned southward. Their north limbs are broken by reverse f a u l t s ; i n this case the north side is upthrown..These are indicated on the map. The northern one has a throw of 1500 feet, and dies out near Chemainus River. The southern one has a stratigraphic throw of probably 4000 feet and continues on up Cowichan Valley, The Leech River f a u l t (Clapp, 21, p. 277), twenty miles to the south has a similar trend to the Cowichan f a u l t . I t is a reverse f a u l t of moderately low angle, and brings Paleozoic against the Eocene Metchosin volcanics. The estimated s t r a t i -graphic displacement i s 7500 feet. Relations to Older Formations; The series rests with angular unconformity on a l l older rocks. These are in most cases volcanics with interbedded limestone, a r g i l l i t e and auart-z i t e , belonging to the Vancouver Group of Late Paleozoic to Lower Jurassic age. They are generally steeply folded along axes trending N 65° W. Minor areas of intermediate plutonics, (94) correlated with the Saanich Granodiorite and intruding the Vancouver Group, l o c a l l y form the basement for the Upper Cretaceous rocks. The surface of deposition i s one of considerable r e l i e f and Irr e g u l a r i t y . At Departure Bay (Clapp, 19, PI. 5B), the Cretaceous can actually be seen f i l l i n g i n i r r e g u l a r i t i e s on the old surface. In the Nanaimo Area a r e l i e f of 2000 feet in a distance of two miles i s indicated. This feature is well des-cribed by MacKenzie in the Cumberland Area (61), wher irregular-i t i e s of as much as 440 feet of r e l i e f have interrupted the coal horizons. Relations to Younger Formations; No dated formations older than Pleistocene are known to occur in contact with the Nanaimo Series. Minor intrusives are known to cut them. In the Nanaimo Area a small dike of Dacite porphyry intrudes the Benson conglomerate. A s i l l - l i k e body of similar rock apparently i n -trudes the Upper Cretaceous shales near Alberni. A number of dikes, s i l l s , and small stocks of dacite, granodiorite and auartz d i o r i t e are intrusive i n the area'" NW of Courtenay and NE of Mt. Albert Edward (48). These are correlated with the Lower Oligocene igneous a c t i v i t y represented by the SoOke Intrusives on the south end of Vancouver Island (21), Conditions of Deposition; The fauna indicates that the sedi-ments were deposited i n a marine environment. This sea advanced over an area of l i t t l e less r e l i e f than that of the present surface. The f i r s t deposits would be in estuaries. Thick con-glomerates formed l o c a l l y where rapid streams discharged. At other places the adjacent land was low and no streams discharged (95) in the v i c i n i t y , so "that shales were l a i d down d i r e c t l y on the old surface. The shales and arkoses represent extremes of sedimentation. The recurring persistent shale bands indicate r e l a t i v e l y long periods of quiet erosion over the whole area, while the much thicker beds of arkose and conglomerate indicate short periods of rapid'erosion and deposition brought about by rapid u p l i f t of the source lands. Lateral variations of thickness and character of the beds indicate near-land conditions of deposition, where l o c a l drains age and l o c a l topography influence the sediments. The Upper formations are not known to - contain marine f o s s i l s , but do contain a few land plants. I t is possible that the basin was cut off from the sea near the close of the period and t e r r e s t r i a l though s t i l l aqueous, conditions followed. The source of much of the material was from Vancouver Island i t s e l f . The heavy beds of coarse e l a s t i c s i n the upper part of the series probably came from the Coast Range. Age and Correlation? Large* f o s s i l collections from the v i c i n i t y of Nanaimo and Cumberlan were made by Richardson (81). These came p r i n c i p a l l y from the lower parts of the section. Whiteaves (95) determined them and gave the age as Upper Cretaceous, equivalent to the Chico of Ca l i f o r n i a and Oregon, the Fox H i l l s of the plains, and the Senonian of Europe. No new f o s s i l s have been determined, and the age remains as orig i n -a l l y stated. The f o s s i l s were c h i e f l y marine invertebrates, but a few land plants were also found. The fauna contained a few species in common with Queen Charlotte Islands Cretaceous, but was on (96) the whole quite d i s t i n c t and considerably younger. Dawson suggested that the highest parts of the series may be Eocene. There is no evidence, for t h i s , and no requirement from the point of view of time involved i n deposition. Time of Deformation- There i s no direct evidence of the time of deformation. Since the deformation i n the Nanaimo Series is no greater than that i n the Metchosin Volcanics or the Puget Group of Upper Eocene age, and since the axes of folding have the same trends, i t i s l i k e l y that the main deformation did not take place t i l l early Oligocene. It i s note-worthy that Eocene strata do not occur above the Cretaceous on Vancouver Island, nor does the Cretaceous underlie the Eocene i n Washington. This points to a general cessation of sedimentation near the close of the Cretaceous and a pronounced s h i f t i n g of the basin depos-i t i o n to the east and south. On the east there i s no physical barrier between the Cretaceous and Tertiary. The two may be conformable somewhere under the S t r a i t of Georgia. On the south however, there seems to be a definite axis of Paleozoic rocks, of which the San Juan Islands are a part, which separates the two basins. SUMMARY OF GEOLOGIC HISTORY Toward the close of the Jurassic, much of the present map-area was under marine waters. North of 53rd. p a r a l l e l on either side of the present coast range, great thicknesses of volcanics and marine e l a s t i c s accumulated to form the Hazelton Series. The Coast Range i t s e l f may have begun to r i s e and supply sediments for the basins on either side, but no large (97) areas of batholithic rocks were exposed. There was no apprec-iable interruption of deposition through the whole Jurassic. South of 53rd, p a r a l l e l , along the east flank of the Coast Range, as i n the Bridge River area, Harrison Lake and the Similkameen area and on Vancouver Island, there was an hiatus or a mild unconformity with the e a r l i e r Mesozoic. In a l l of these but the,Bridge River area, batholiths were exposed before the close of the Jurassic. In the northern area again there was folding very near the close of the Jurassic, and extensive intrusion of batholiths. East of the main Coast Range, as at Hazelton, Topley, etc. there may have been no steep structure at this time. In any ease the Skeena formation followed rapidly in the Lower Cretaceous, be-ginning with marine conditions over wide areas, and giving way to continental conditions without much thickness developing. Continental conditions have remained to the present. Volcanics and l o c a l basins of sediments continued to form through to Upper Cretaceous, and possibly into the Tertiary. In the southern area again 'the basins of deposition are unbroken between Jurassic and Cretaceous. In Bridge River area marine conditions with volcanics continued into the Lower Cretaceous with only a minor disturbance close to the beginning of the Cretaceous. This is. revealed i n the conglomerate belt. No batholiths were yet exposed. In the Harrison Lake area, a low-angle unconformity is suspected between the Jurassic and the Cretaceous. In the Similkameen area, a great basin - continuous with that i n the Bridge River area - persisted t i l l nearly Upper Cretaceous. I t was marine t i l l Barremian at least, and volcanic material contributed extensively.. About Barremian time, (98.) a great conglomerate formed as a result of strong u p l i f t , possibly folding and intrusion, i n the area adjacent to the basin. After this the basin apparently shifted east against a highly elevated land with a dry climate and with considerable granite, rock exposed. A great thickness of arkose was then deposited i n the basin under continental conditions. This may have persisted t i l l Cenomanian. A similar basin lay twenty to th i r t y . miles, to the south west, where,the Tamihy^Series was deposited. Northeast of the Similkameen basin were others in which mostly volcanics with some continental sediments were accumulated. I t i s thought that they were mostly later than the deposits of the main basin, though they may have been contemporaneous i n part. They are d e f i n i t e l y later i n the Bridge River area, and possibly unconformable on the Cretaceous sediments. On the mainland of B. C. there i s no sedimentary record beyond Cenomanian, Volcanism probably persisted, and possibly l o c a l sediments are yet to be found. Apparently the area was emergent, though at the same, time the Great Plains region was . flooded as widely as i t had ever been. In. the Coastal Trough,- thick series of sediments were de-posited. The areas had been emergent since Jurassic,, except for a small submersion covering northwest Vancouver Island in Lowest Cretaceous, Sedimentation in the trough began on Queen Charlotte Islands, and involved Cenomanian and Turonian time at least, depositing 8000 feet of marine near-shore, and f i n a l l y continental, coarse e l a s t i c s . Deposition was then taken up i n the Nanaimo basin, where 10,000 feet of similar sediments were deposited. Those i n the upper part of the section are near (99) Tertiary i n age. Their character indicates high source lands. The (Queen Charlotte deposits seem to demand a granite borderland, either to the east or to the west, as source area. Those of Vancouver Island came from the Island i t s e l f - not necessarily larger but more elevated than at present - and from the Coast Range on the mainland. There was probably no folding i n the Nanaimo basin between the Cretaceous and the Tertiary, but there was certainly a cessation i n sedimentation, and a s h i f t of the basin of deposi-tion to the east and- south, into which the Eocene sediments of similar character began to accumulate. To sum up the age evidence of the batholithic rocks:- We have in the northeast, evidence that some granitic rocks were exposed before the Middle Jurassic. These were well east, and d i s t i n c t from the Coast Range intrusives. The same may be true farther south, from the evidence of the Ashcroft rocks. Large volumes of the Coast Range intrusives on the mainland and on the Islands south of, roughly speaking, the 51st. p a r a l l e l , were emplaced and rapidly unroofed before the Latest Jurassic. These coincide generally with the Nevadan intrusives of C a l i f o r n i a . In the main Coast Range and Islands north of, for conven-ience, the 53rd. p a r a l l e l , large intrusions seem to be coincident with the close of the Jurassic, and smaller intrusives cut folded Lower Cretaceous, east of the main batholith. There are no proven Cretaceous batholiths. This may be because there are not enough Upper Cretaceous strata to overlie them. There are many post-Lower and some post- Upper Cretaceous Intrusives. Apparently a l l the batholithic rocks l y i n g between 51 and 52 N. Lat. i n the main Coast Range are later than the (100) folding of Cenomanian strata. Large masses east and south of Harrison Lake cut older intrusives and folded Cretaceous rocks as young as Cenomanian. There i s good evidence i n the Harrison Lake area that the folding of the Cretaceous rocks, that i s the deformation of the Cascade Range, did not take place t i l l Tertiary. The folding of the entire.belt east of the Coast. Range may well have been an Oligocene event, and hence the i n -trusives are this age or younger.: Small intrusives of definite Tertiary age are of course known on Vancouver Island. Large batholiths are known i n the Cascades of Washington. (101) BIBLIOGRAPHY 1. Allan, J. 'A.,.-. The Geology of Saltspring Id. and the East Coast of Vancouver Id. G. S. C., S. R. 1909. 2. Anderson, F. M.,- The Knoxville-Shasta Succession in . C a l i f o r n i a . G. S. A. B u l l . , v o l . 44, 1933. 3. B a r r e l l , Joseph,- Rhythms and the Measurement of Geologic Time. G. S. A. B u l l . , Dec. 1917. 4. Barton, D. C- The Geological Significance and Genetic C l a s s i f i c a t i o n of Arkose Deposits. J. Geol. 24, 1916, 5. Bateman, A. M.- L i l l o o e t Map-Area, G. S. C., S. R. 1912 6. .Bauerman, H.,- Rpt. on the Geol. of the country near 49th. p a r a l l e l of N La.t., west of the Rocky Mts. , G. S. C. , : Rpt. of Prog. 1882. 7. Berry, E. W.- The age of Certain Mesozoic Formations i n Western Canada, R. S. C., Proc. & Trans. XX-1926. 8. , Bowen, N. L.- Geol. of Fraser Valley between Lytton and Vancouver. G....;S. G., S. R. 1912. 9. Brock, R. W.- Eutsuk Lake B. C., G. S. C., S. R. 1920 10. Brown, Barnum,-'Cret.-Eocene contact i n N. Mex., Wyoming, Montana, and A l t a . , G. S. A. B u l l . , v o l . 25, 1914. 11. Cairnes, C.E.-• Recc along the Kettle Valley Railway, Canyon House to Coquihalla G. S. C, S. R. 1922. 12. Recc. between Coquihalla. Stn. and Tulameen Mtn. G. S. 0.; S• R. 1922. . 13. Recc. along the Dewdney T r a i l , G. S. C., S. R. 1922. 14. Coquihalla Area, G. S. C., Memoir 139, 1924. 15. Recc. i n the Drainage Basin of the Skagit etc. Rivers, G. S. C., S. R. 1923. 16. Camsell, Charles-Geol. Investigations i n Yale and Similkameen Mng. Div., G. S. C., S. R. 1911. 17. Coast Range - Lytton to Vancouver, Int. Geol. Cong., Guide Book 8 pt. 2, pp 256-273. 18. Clapp, C. H.- Nanaimo Co a l f i e l d , G. S. C., S>. R. 1911. (102) 19. Clapp, 0. H.- Nanaimo Map-Area, G. S. C. Mem. 51, 1914. 20. " A Geol. Recc. on Graham Id. G. S. C. Summary Rpt. 1913 pp 12 - 40. 21. " - Sooke and Duncan Map-Area, G. S. C. Mem. 96, 1917. 22. Crickmay, C. H.- The Jurassic Rocks of Ashcroft B. C., "Univ. of C a l i f , pubns. - B u l l , of Dept. of Geol. Sciences. Vol. 19, no. 2 - 1930. 23. " - The Structural Connection Between the Coast Range of B. C. and the Cascade Range of Washington. Geological Magazine, v o l 67, - 1930. 24. Culver, H. E. - Geol. of Wash., Pt. 1 - General Features of Washington Geology. To accompany preliminary geologic map - 1936. State of Wash. Dept. Of Conservation and Development - B u l l . 32. 25. Daly, R. A.- North American Cordillera at the 49th P a r a l l e l . G. S. C. Mem. 38, 1912. 26., Dawson, G. M.-, Explorations i n B. C. G. S. C , Rpt. Prog. 1875-76. 27. Southern B. C. - Prelim. Rpt. G. S. C. R.P. 1877-78. 28. Queen Charlotte Ids. G. S. C., Rpt. Prog. 1878-79. 29. North part of Vancouver Id., and adjacent Ids. G. S. C, Rpt. Prog. 1886. 30. Notes on the Cretaceous of the B r i t i s h Columbian. Region - The Nanaimo Group, Am. J. Sc. 39, 1890. 31. Report on the Kamloops Map-Sheet. G. S. C. Ann. Rpt..7, 1894 -B 32. D i l l e r , J. S. & Stanton, T. W.- The Shasta-Chico Series. B u l l . Geol. soc. Am., v o l . 5 - 1894. 33. Dolmage, V.-West Coast of Vancouver Id,, between Barkley and Quatsino Sounds. G. S. C , S. R. 1918-19-20. 34. Chilko Lake B. C. and V i c i n i t y . G. S. C., S. R. 1924. 35. Tatla - Bella Coola. G. S. C., S. R., 1925. 36. Gun Creek Map-Area. G. S. C, S. R. , 1928. 37. Dowling, D. B.- Coal Fields of B. C. G. S. C, Mem. 69, 1915. 38. Drysdale, C. W.- Savona to Lytton. G.S.C., S.R. ' 1912. (103) .39. Drysdale, G. W.- Explorations i n Bridge River Area, G.S.C, S.R. 1915. 40. Du Toit, Alex.- Geology of South Afr i c a . 1939. 41. E l l s , R. W.- Graham Id. B.C. G.S.C, New Series-16, 1904. 42. Evans * .H. P.- The Cretaceous Stratigraphy of Ashcroft B.C. Mining World, 23 - 1905. 43. Galloway, C. E. J.- Rpt. on the Coal Measures of Peace River Canyon. Ann. Rpt. B.C. Min. of Mines 1912. 44. Gilbert, G. K.- The Sedimentary Measurement of Cretaceo\is Time. Hournal Geol. 3, 1895. 45. Goodman, Clark, and Evans, Robley D.- Age Measurements by Radioactivity. B u l l . G.S. A., A p r i l 1941. 4.6 Gorans on, R. W.- A Correlation of Mesozoic Formations of the P a c i f i c Coast of North America. Am. J. Sc. 5th. Series, 1924. 47. Gunning, H. C- Quatsino-Nimkish Map-Area. S.R. 1929. 48. " - Buttle Lake Map-Area. G.S.C., S.R. 1930. 49. Hanson, G.- Recc. between Skeena R. and Stewart B.C. G.S.C*, S.R. 1923. 50. " - Hymoetz River Area. G.S.C., S.R. 1925. 51. Horwood, H. C - Prelim. Rpt. on south part of Fraser River - Harrison Lake Region. G.S.C. 1936. 52. Kindle, E, D.- Min. Resources, Terrace Area B.C. G. S. C.,f.Mem. 205, 1936. 53. " r--, Min. Res., Usk to Cedar vale B. G. G.S.C./Mem. 212, 1938. 54. Knowlton, et a l - Cretaceous-Tertiary Bdry. i n the Rocky Mountain Region. G.S.A., B u l l . 25, 1914. 55. Lang, A. H.- Owen Lake Mining Camp B.C. G.S.C., S.R. 1929. 56. Leach, W. W.- Skeena River Dist. G.S.C, S.R. 1909-10. 57. .Lee, J. S.- The Geology of China. 1939. 58. LeRoy, 0. E.- Coast and Islands, B.C. G.S.C., Pubn. 996 1908. 59. MacKenzie, J. D.-Geol. of Graham Id. B.C. G.S.C , Mem. 88, 1916. (104) 60. Recc. between Taseko L. & Fraser R. B.C. G.S.C, S. R. 1920. 61. The Coal Measures of Cumberland.and V i c i n i t y , Vancouver Id. B.C. B u l l . C.I.M.M., Jan". 1922. 62. Alberni Area, Vancouver Id. B.C. G.S'. C. , S.R. 1922. 63. Mailoch, G. S. - Recc. on Upper Skeena River between 5Hazelton and the Grounding Coal Fi e l d B.C. G.S.C., S.R. 1911. 64. Martin, G.C.- The Mesozoic Stratigraphy of Alaska. U. S. G. S., B u l l . 776 - 1928. 65. Mathews, W. H.- Black Tusk Area. Univ. of B.C. Essay, 1939. 66. Mathew, W. D.- Evidence of paleocene Vertebrate Fauna on the Cretaceous-Tertiary problem. G.S.A. B u l l . 1914. 67. McCann, W. S.- Geol. and Min. Dep. of Bridge River Area. G.S.C., Mem. 130, 1922. 68. McConnell, R. G.- Prince Rupert to Aldermere. G.S.C., S.R. 1912. 69. " - Texada Id. B.C. G.S.C. Mem. 58 1914. 70. McLearn, F. H.- Cretaceous of Peace and Athabasca Valleys. G.S.C., Mem. 116, 1919. 71. " - Mesozoic of Upper Peace River B.C. G.S.C., S.R. 1920. 72. "" - Cretaceous i n the Rocky Mts. G.S.C. Museum B u l l 58, 1925. 73. McLellan, R. D.- Geology of San Juan Ids. Univ. of Wash. pubn. i n Geol, 2, 1927. 74. Osborn, H. F.- Close of Cretaceous Opening of Eocene in North America. G.S.A. B u l l . v o l . 25, 1914. 75. " - Close of Jurassic Opening of Cretaceous in North America. G.S.A. B u l l . v o l . 26, 1915. 76. O'Neill, J,- J.- Prelim. Rpt. on the Ec. Geol. of Hazelton Dist., B.C. G. S. C., Mem. 110, 1919. 77. Raymond, P. E.- The Significance of Red Color i n Sedimentation. Am. J. Sc. 13, 1927 78. ReinecKe, L.- L i l l o o e t to Prince George. G.S.C., Mem 118. 79. Rice, H. M. A.7 Cranbrook Map-Area 1 B.C. Mem.. 207, 1937. (105) 80. Richardson, James.- Coal-Bearing Rocks of Queen Charlotte Ids. G.S.C, Report of Progress 1872-73. 81. " - Coal Fields of Nanaimo,'Comox etc. G.S.C, Report of Progress 1876-77. 82. Russell, I. C- Recc. on the Geology of the Cascades. U.S.G.S., 20th. Ann. Rpt. 1900. 83. Russell, L. S. and Landes, R. W.- Geology of the South Alberta Plains. Mem. 221, 1940. 84. Schuchert, C- Sites and Nature of the North American Geosynclines. B u l l , G.S.A. v o l . 34 - 1923. .85. Schuchert, C , Lane, A. C , Holmes et a l - The Age of the Earth. Nat. Res. Council. B u l l . 80 - 1931. ; 86. Schuchert, C- Outlines of H i s t o r i c a l Geology. Wiley, 1931, 87. Smith, G. 0. and Calkins, F. C. - Geological Recc. across the Cascades of Northern Washington, U.S.G.S. B u l l . 235 - 1904, 88. Stamp, L. D.- Introduction to Stratigraphy, Murby, 1923. 89. Stanton, T. W.- A Comparative Study of Lower Gretaceous. Formations and Faunas of U. S. J, Geol. v o l . 5, 1897. 90. " - Boundary between the Cretaceous and Tertiary i n North America as Indicated by Statigraphy and Invertebrate Fauna. B u l l . G.S,A. v o l . 25, 1914. 91. Stephenson, L. W. et a l - Cretaceous Formations of the Atlantic and Gulf Coastal P l a i n . Chart 9 of the National Research Council, B u l l . G.S.A. March, 1942. 92. Taliaferro, N. L, - Geological History and Correlation of the Jurassic of Southwest Oregon and California" B u l l . G.S.A. January, 1942. 93. Twenhofel, W. H.- Principles of Sedimentation, McGraw-Hill 1939. 94. Wadiec, D. N. — The Geology of India.. MacMillan, 1939. 95. Whiteaves, J."F.- Mesozoic Fos s i l s . Vol. 1. Pt. V. 1903. 96. Williams, M. Y. and Dyer, W. S.-_ Geology of So. Alt a , and Southwest Sask. Mem. 163, G.S.C 1930. Maps 1. Vancouver Sheet, Geological Survey of Canada, 1928. 2. Prince Rupert Sheet, " ' , 1933. 3. Fort Fraser, E and W h a l f , " , 1941. 4. Prelim. Geol. Map of Washington, Wash. Geol. Survey, 1936. Appendix 1. Fig. 1 - Spec. 13 xl8 Shows F i g . 2 - Sp. 7 x270 x-nicrls the general microscopic Shows fresh feldspar character of the arkose and packed quality of from the lower part of the angular "grains i n the Roche River fmn. Roche River fmn. Fig. 3 - Sp. 25 x60 Andesite c r y s t a l - l i t h i c t u f f F i g . 4 - Same as 3 with crossed nicols. IMTOTBy- and FASAYTEN ROCKS Map A/o.2. eneral Map Showing Scale: 1 In 4 mi. Symbols Faulij *9 ive bdry. . bdry. tZO" 'rfppen d'/V 4-. GEIISRALJ.IAP or the NAHAILiX Scale : l|in.= 8ni. Intrusives PA CIFIC OCEAN 


Citation Scheme:


Citations by CSL (citeproc-js)

Usage Statistics



Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            async >
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:


Related Items