POST-GLACIAL LAKES IN CANADA 



349 



in all the valleys can only point to the fact that the waters were in 

 conjunction with one another. Those in the Hay and Peace river 

 valleys undoubtedly were connected through straits between 

 Caribou Mountains and Watt Mountains. The other connections 

 were apparently by marginal channels along the ice front. Drain- 

 age northward by way of the Mackenzie River was blocked, and it 





Fig. II. — Outline map showing probable position of Keewatin ice sheet and 

 lake expansions when the water stood at the i,6oo foot level. 



seems likely that the lake in the Athabaska Valley was somewhat 

 lower in level than the others, and may have been drained eastward 

 toward Hudson's Bay. The more probable outlet, however, was 

 by way of the Clearwater River and Methy portage to the Churchill 

 River Valley. The summit of Methy portage is 1,735 f^^t above 

 sea-level — scarcely more than 200 feet higher than the lake level 

 at that stage. This difference could easily be accounted for by 



