LAURBNTIDE AND CORDILLEEAN GLACIERS. 119 



hundreds of miles wide, reaching from the Rocky Mountains and the 

 Upper Mackenzie to Reindeer Lake and La|ie Winnipeg, the southwestern 

 pai-t of Hudson Bay, James Bay, the Laiirentide highlands, and the 

 southern part of Labrador. 



This proposition, however, differs widely from the opinions of Mr. J. B. 

 Tyrrell, who thinks that a narrow unglaciated tract (designated on Pis. II 

 and XVI as a "debatable tract") borders the eastern base of the Rocky 

 Mountain range in Canada,^ and of Dr. Dawson, who doubts that an ice- 

 sheet has ever existed on a much wider area stretching from the Rocky 

 Mountains far eastward across the Peace and Saskatchewan plain country 

 nearly to Lake Athabasca and the lakes of Manitoba." It is needful, 

 therefore, that the evidences of glaciation in that district should be defi- 

 nitely and particularly stated. Without considering- here the methods of 

 formation of the various drift deposits, it may make my views more readily 

 understood to add that I agree perfectly with Mr. Tyrrell in referring- all 

 deposits of bowlder-clay or till directly to the agency of land ice, without 

 modification or aid by water; while Dr. Dawson, on the other hand, refers 

 all these deposits of till to a glacio-natant origin — that is, to deposition 

 from floating ice supplied from glaciers and borne over the till-covered 

 areas during their submergence by lakes or the sea. 



LAUREXTIDE AND CORDILLERAN CENTERS OF OUTFLOW. 



The prevailing courses of glaciation and dispersal of the drift lead me 

 to recognize, with Dr. Dawson, the existence of two central areas upon 

 which the ice was accumulated in greater depth than elsewhere, and from 

 which consequently it flowed outward on all sides.^ One of these areas 



' Bulletin, G. S. A., Vol. I, pp. 396, 400, 401. 



'Trans., Roy. Soc Can.ada, Vol. VIII, sec. 4, pp. 54-74. 



'Dr. George M. Dawsen, Geol.aucl Nat. Hist. Survey of Canada, Annual Report, new series. Vol. 

 II, for 1886, pp. 56-58 R; Geol. Magazine, (3), Vol. V, pp. 347-350, Aug.. 1888; Am. Geologist, Vol. VI, 

 pp. 153-162, Sept., 1890; Transactions, Royal Society of Canada, Vol. VIII, sec. 4, 1890, pp. 3-74, with 

 five maps. 



Compare with Dr. Robert Bell's opinion, based on his observations throughout the eastern two- 

 thirds of British America, that during the Ice age "the b.asiu of Hudsons Bay may have formed a 

 sort of glacial reservoir, receiving streams of ice from the east, north, and northwest, and giving forth 

 the accumulated result as broad glaciers, mainly towards the south and southwest," and also to the 

 northeast and east through Hudson Strait. Geol. and Nat. Hist. Survey of Canada, Report of Progress 

 for 1882-83-84, pp. 36, 37 DD. 



Also see an article by Prof. E. W. Claypole, on "Glaciers and glacial radiants in the Ice age," 

 Am. Geologist, Vol. Ill, pp. 73-94, Feb., 1889. 



