THE CHAMPLAIN SEA IN THE LAKE ONTARIO BASIN 543 



withdrawal from the maximum of submergence to the present maxi- 

 mum of emergence. Data now available, however, lead to the 

 conclusions that, when the ice barrier was removed from the St'. 



v v ( 1 1 1 ' 1 1.1 1 1 1 1 1 "'■ ' 1 1 4 ,.■■ j 



LRK£ IROQUOIS 



AT TH£ T/MC THE 



COVEY OUTLET 



WAS ESTAB Li SHED 



Fig. 1. — A late stage in the history of Lake Iroquois. Lake Algonquin, a portion 

 of which is shown in the Georgian Bay region, overflows through the Fenelon Falls 

 outlet east of Kirkfield, Ontario, and Algonquin River carries its waters to the Rice 

 Lake embayment of Lake Iroquois. The Niagara River outflow from Lake Erie also 

 contributes to Lake Iroquois, which is indicated in its two-outlet stage. Part of its 

 water spills into the Mohawk Valley near Rome, New York, and part falls over the 

 cliff at Covey Gulf, Quebec, into the marine embayment in Champlain Valley. St. 

 Lawrence and Ottawa rivers and parts of the present Great Lakes are indicated by 

 dotted lines. Pleistocene geography based largely upon the work of Fairchild, Cole- 

 man, Johnston, and Taylor. 



Lawrence Valley north of Covey Hill, the level of the Champlain 

 Sea was far below its maximum height, and that the strand line 

 moved gradually up the valley of the St. Lawrence River and its 



