HYPOTHESIS OF NOKTHEASTWARD OUTFLOW. 233 



or higher.' Perhaps, last of all, before the glacial recession admitted the 

 sea to Hudson Bay, this discharge from Lake Agassiz, flowing through a 

 great glacial lake in the southwestern part of the basin of Hudson and 

 James bays, would find its lowest and final outlet to the south by the way 

 of Lakes Abittibi, des Quinze, and Temiscaming, then entering the Ottawa 

 arm of the Gulf of St. Lawrence. It seems even possible that the vicissi- 

 tudes of the changing courses of drainage produced by the gradual retreat 

 of the ice may hnve included for the outflow from Lake Agassiz, after 

 it began to pass first northeastward, all of these four ultimate routes; first, 

 by Chicago to the Mississippi; second, by the glacial Lakes Algonquin, 

 Lundy, and L-oquoi.s, and the Mohawk and Hudson rivers, to the Atlantic; 

 third, by the lake portion of this route, and perhaps for some short time by 

 Lake Nipissing and the Mattawa River, to the head of the Gulf of St. Law- 

 rence, then filling the St. Lawrence Valley and a part of the Ottawa basin; 

 and fourth, by Lake Abittibi, crossing the lowest point of the watershed 

 between James Bay and the St. Lawrence. The known epeirogenic subsi- 

 dence of the Chaniplain epoch and the probable manner of recession of 

 the ice border from sonth to north make each and all of these courses, 

 diverting the northeastward outflow to the south, far more probable tlian 

 either of the courses before considered by which this glacial lake might be 

 supposed to send its overflow to the Mackenzie. 



Division of the ice-sheet info parts east and west of Hudson Baij. — It seems 

 to me most probable, however, that long before the complete departure of 

 the ice-sheet it became melted in twain by the laving action of Lake Agas- 

 siz and of a great glacial lake in the southwestern and southern part of the 

 basin of Hudson Bay, and on its other side by the sea washing its ice-clifts 

 in Hudson Strait and the northern part of Hudson Bay, so that the latest 

 general glaciation of our continent was confined to two areas, one east and 

 the other west of this vast mediterranean sea. Several of the lower shore- 

 lines of Lake Agassiz, formed during its northeastward drainage, if not 

 all of them, doubtless mark levels of outlets which flowed into this inland 

 sea, until the northward recession of the remnant of the ice-sheet on its 

 west side laid bare the course of the Nelson. Careful collection and study 



' Am. Jour. Sci. (3), Vol. XLIX, pp. 1-18, with map, Jau., 1895. 



