GLACIO-LACUSTK I N K STAGE 



639 



valley was freed from ice, it offered the lower outlet, and the level of 

 Lake Warren was drawn down, and it was divided into two lakes, 

 Kile and Iroquois (Fig. 530). 



Meantime, the glacial lakes in the basins of Lakes Michigan and 

 Superior experienced analogous shiftings of areas and of outlets. 

 While Lake Iroquois was discharging through the Mohawk valley, 

 Lake Algonquin (Fig. 530), was discharging its waters eastward. 

 At first the outlet was probably by the St. Clair-Erie route, through 



V\K. 530. The Great Lakes at the Algonquin-Iroquois stage. 

 UH- sea is by way of the Mohawk Valley. (Taylor.) 



Lake Iroquois, to the Mohawk; but later, when the ice had retired 

 farther north, an outlet appears to have been opened from Georgian 

 Bay to Lake Iroquois, by way of the Trent River. 



When at length the ice withdrew from the Adirondacks so far as 

 to permit the waters of Lake Iroquois to find an outlet lower than 

 that by way of the Mohawk, a new series of lowerings of the lakes 

 followed. At first the outlet seems to have skirted the Adirondacks 

 and emptied into a glacially-ponded water-body (glacial Lake 

 Champlain) which occupied the Champlain basin, and discharged 

 southward through the Hudson. Later Lake Algonquin gave place 

 to the great Nipissing Lakes (Fig. 531), which had their outlet via 

 Lake Nipissing to the Ottawa, and thence to the Champlain arm of 



