abstracts: geology 19 



The rivers that issued from the great reentrants of the ice front 

 carried enormous quantities of sediment, the coarser parts of which were 

 spread over extensive areas in front of the ice. The soils thus produced 

 are lower in fertile than those of the intervening moraines and till 

 plains. 



The larger lakes began with glacial Lake Maumee which first appeared 

 as a small crescent-shaped body of water bordering the ice front with 

 its outlet at Fort Wayne, Indiana. In a similar manner glacial Lake 

 Chicago soon appeared at the south end of the Lake Michigan basin. 

 The bearing of certain facts observed in Ohio on the attraction of the 

 ice sheet upon the lake waters near it is discussed in connection with 

 Lake Maumee. Remarkable ice ramparts formed in connection with 

 the same lake are also described. With further recession of the ice 

 these lakes expanded northward until Lake Maumee found a lower 

 outlet westward across the "thumb" of Michigan 50 miles north of 

 Detroit. About this time a lake made its appearance in the Saginaw 

 valley and from this point the history of lake waters is involved in 

 considerable complexity. This complexity arose mainly from the oscil- 

 lation of the ice front, and from its relation to certain parts of the land 

 whose form and relief caused them to become barriers at climaxes of 

 readvance but not at climaxes of recession. These barriers were: 

 (1) the broad low ridge forming the "thumb" of Michigan, and (2) 

 the northward sloping front of the highlands south of Syracuse, N. Y. 

 In both of these regions, first on the "thumb" and then near Syracuse, 

 outlets for the lake waters were alternately opened and closed by the 

 oscillating ice front and the level of the waters was alternately lowered 

 and elevated correspondingly. Following Lake Maumee, the waters 

 underwent a number of changes of level and of outlet, forming succes- 

 sively Lakes Arkona, W^hittlesey, Wayne, Warren, and Lundy. 



At length the lowland between the Huron and Erie basins was left 

 dry and St. Clair and Detroit rivers began their post-glacial existence. 

 Similarly the lowland between Lakes Erie and Ontario emerged and 

 Niagara River and the great cataract came into being. Soon after the 

 appearance of early Lake Algonquin in the south half of the Huron 

 basin the waters in the three upper basins, those of Superior, Michigan, 

 and Huron were united, forming the great Lake Algonquin, the largest 

 of the glacial lakes of the region. Twice the recession of the ice opened 

 outlets for Lake Algonquin, but on both occasions these were closed by 

 differential elevation of northern lands. The first was at Kirkfield, 

 Ont., and the second at North Bay, Ont. The uptilting of the land at 



