8l4 /. BURR TYRRELL 



crossing the Saskatchewan River at the Pas, was formed in the 

 bed of this lake. 



Meanwhile the eastern glacier was advancing towards its 

 extreme western limit near the west shore of Lake Winnipeg, 

 for it never crossed the belt of land intervening between that 

 lake and lakes Manitoba and Winnipegosis. Before it reached 

 the mouth of the Saskatchewan River, on the west side* of this 

 lake, the Keewatin glacier had already retired a considerable 

 distance farther north, a sufficient time having elapsed to permit 

 of the deposition in the bed of the lake of at least twelve feet of 

 thinly and evenly stratified sands and clays over till of the ear- 

 lier glacier, before they were covered by the till of the later gla- 

 cier. The section of these two tills, with the intermediate 

 stratified deposits, is well exposed on the bank of the Saskatche- 

 wan River near its mouth, and has been described by the writer 

 in his "Report on Northwestern Manitoba."^ 



The later historv of Lake Agassiz has not yet been definitely 

 determined, but it would seem reasonably certain that the Kee- 

 watin glacier continued to retire northward until it separated 

 from the eastern glacier. Then the water would drain freely 

 around the northern end of the latter glacier to Hudson Bay. 

 The northeastern drainage has been shown by Mr. Upham^ to 

 have begun at the level of the Blanchard Beaches, the highest 

 of which, along the line of the Manitoba and Northwestern Rail- 

 way, is stated to be at an elevation of 994 feet above the sea or 

 284 above the present level of Lake Winnipeg. The eastern 

 glacier seems to have now begun to retire, and its front had 

 retired to a short distance east of -the east shore of Lake Winni- 

 peg when the Burnside and Gladstone Beaches were formed at 

 elevations of from 150 to 170 feet above the present lake. 

 Stratified Lake Agassiz sands and clays were deposited in con- 

 siderable thickness on this side of the lake up to the above level, 

 apparently near the front of the glacier. That the eastern glacier 



'Ann. Rep. Geol. Sur. Can., Vol. V, 1890-1, Ottawa 1893, Part E, p. 146. 

 ^ Report of Exploration of the Glacial Lake Agassiz in Manitoba, by Warren 

 Upham, Ann. Rep. Geol. Srr. Can., Vol. IV, 1888-9, Part E. 



