FORMER GLACIATIO^ IN THE ROCKY MOUNTAIXS. 77 



as has been shown in another place,* so that his statements must be 

 received with some caution. He nowhere, in his official report, speaks of 

 any phenomena of former more extensive glaciation, or of any accumu- 

 lations of the " superficial deposits," as he calls the most recent formations, 

 as having the character of moraines. He considered that he had obtained 

 proofs that the continent was depressed, dming the Northern Drift period, 

 to a depth of nearly 3,000 feet beneath a sea in direct connection with 

 the Arctic Ocean, and that since then, to use the author's own words," during 

 its gradual emergence, the prairie region of North America has received its 

 present form of surface by denudation, first, as effected on sea-coast lines ; 

 secondly, by the coast-lines of great inland lakes, which, it will be shown, 

 though still existing, were previously of much greater dimensions ; and, 

 thirdly, by atmospheric agencies wearing away the soft strata, aided by 

 streams." Dr. Hector speaks of the "glacial markings" on the rocks of 

 Vancouver Island, to which reference will be presently made. He saw soli- 

 tary boulders of great size resting on the '•' shingle terraces " — and by tliis 

 term he evidently means the local drift accumulations — " in the woods to 

 the south of Fraser River," at a height not more than 100 or 200 feet above 

 the sea-level. In his final summing up of the drift phenomena of the Pacific 

 Coast, he remarks as follows : " As I never observed drift or boulders within 

 the Cascade Range, even in places elevated only 600 or 700 feet above the 

 sea, but as all the superficial deposits in the great trough between that range 

 and the Rocky Mountains clearly are formed from the re-arranged materials 

 of the shingle terraces, along with tufas from the Cascade Range, I conclude 

 that the average lowest altitude of the Cascade Range, which is somewhere 

 about 4,000 feet above the sea at the present time, exceeded the depression 

 of the continent during the glacial epoch, and presented a barrier to the 

 causes which transported the erratics and scratched the rock-surfaces along 

 the Pacific Coast. If the Cascade Range at that time formed a jjrom- 

 ontory enclosing a gulf open only to the south, like the Gulf of California, 

 it would exactly fulfil these conditions." 



In regard to the former glaciation of the Rocky Mountains, where crossed 

 by the boundary line, in latitude 49^, we have the statements of Mr. G. M. 

 Dawson, the Geologist of the British North American Boundary Commission, 

 who speaks of the effects of glaciers as being frequently apparent along his 

 route. The descriptions given, however, do not convey the idea that the 



* See Auriferous Gravels of the Sierra Nevada of Calilbruia, pp. 69, 70. 



