M O R L WORK Oh NIAGARA RIVER 



lines, north of which the beaches arc upcanted somewhat 

 as a partly-opened trap door. The hinge Hne north of wliich 

 the continent first uphfted extends from Aslitabula, Oliio, 

 northwestward across Lake St. Clair, and bends to Lake Michi- 

 gan west of Grand Rapids. South of that line the Lake 

 Whittlesey beaches are horizontal; north of it they are up- 

 tilted. That the uplift was somewhat spasmodic is shown 

 by the fact that the Lake Warren beaches are uptilted north 

 of another hinge line about fifteen miles north of and parallel 

 to the Whittlesey hinge. 



By these deformed beaches we know that the forces of 

 continental uplift were active even before the time of Lake 

 Algonquin, but they had played no very important part as 

 yet in the development of the lakes. By the time the Kirk- 

 field outlet of Lake Algonquin was well established, and a river 

 wider than the St. Clair had scoured a broad channel down 

 the Trent River valley, and the lake had made well-defined 

 beaches and other shore formations, the continent began to 

 rise more rapidly; then the waters of the lakes were spilled 

 southward out of their basins and again found their old out- 

 lets past Port Huron and Chicago; and for a time Lake 

 Algonquin had three outlets: to Lake Iroquois, to Lake Erie, 

 and to Mississippi River through the old Chicago outlet. 

 (Figure 14.) Spilling the waters on the south shores destroyed 

 the beaches of the Kirkheld stage in Michigan, but they are 

 preserved around Duluth and in the Ontario areas. The down- 

 cutting, and therefore lowering, of the outlet past Port Huron 

 diverted the overflow from the Chicago outlet, so that in the 

 latter part of this stage Lake Algonquin was drained through 

 lakes St. Clair, Rouge and Erie. Lakes St. Clair and Rouge 

 were small transitional lakes in depressions of the former 

 strait connecting the Huron and Erie basins during Lake 

 Elkton time, and now held the Algonquin overflow. They 

 were large enough and lived long enough to make faint but 

 well-defined beaches. The uplift raised the level of the Rome, 



61 



