82 



Reviews — Geological Survey of Canada. 



Early Pliocene ? 

 Later Miocene. 



Earlier Miocene. 



Oligocene, 

 Earlier Cretaceous. 



Triassic (and Lower 

 Jurassic). 



Upper Palaeozoic 

 (chiefly Carbon- 

 iferous) . 



Tranquille beds. 



Coldwater Group. 



Queen Charlotte 

 Islands formation 



(chiefly) . 

 Nicola formation. 



Cache Creek 

 formation. 



Lower Palaeozoic 

 (chiefly Cambrian) . 



Adams Lake 



Series. 



Nisconlith 

 Series. 



Feet 

 Conglomerates. 

 Volcanic rocks, largely 



basalt 3,100 



Bedded tuffs 1,000 



Volcanic rocks, largely 



porphyrites .., ... 5,300 



Conglomerates and sand- 

 stones 



Sandstones, conglomerates, 

 and argillites 



Chiefly volcanic ; some 



limestones and argillites 



7,500 to 



In Western District. 

 Upper part. — Marble- 

 canon limestone, with 

 some volcanic rocks, ar- 

 gillites, and quartzites 3,000 



Lower part. — Argillites, 

 quartzites, and volcanic 

 rocks, with some lime- 

 stone 6,500 



9,400 

 5,000 

 7,000 



13,500 



9,500 



In Eastern District. 

 Campbell Creek beds? — 

 Argillites and amphi- 



bolites about 5,000 



Argillites and grau- 

 wackes, limestones and 

 volcanic rocks 



7,500 



Chiefly volcanic rocks, 

 with some arkose con- 

 glomerate. Thickness 

 actually observed m 

 Kamloops sheet, 9,500 

 feet. Total thickness 

 in adjacent Adams 

 Lake section 



Chiefly dark argillites. 

 Thickness actually ob- 

 served in Kamloops 

 sheet, 2,000 ft. Total 

 thickness in Selkirk 

 Mountains section ... 



12,600 



17,100 



15,000 



General Section of Kamloops Region 



32,100 

 89,000 



It is regarded as well within the limits of probability to estimate 

 the volcanic materials of the interior plateau region of British 

 Columbia at about 20,000 feet in total thickness. The width of this 

 belt of volcanic rocks may be assumed to be about 100 miles. Tliis 

 vast extravasation must have been accompanied by enormous sub- 

 sidences, which probably corresponded generally with the present 

 position of the coast ranges. There were, however, recurrent 

 periods of elevation which resulted in the production, at more than 

 one period, of a chain of mountains along this line, whicli were 



