THE BIRTH OF NIAGARA FALLS 



as for a time two St. Clair rivers flowed in parallel courses, and 

 Detroit River resembled a wide loosened braid of many 

 strands. But in time the currents chose the eastern channels 

 and took almost their present courses. When these rivers 

 developed, the lakes in the Huron and Hrie basins were finally 

 separated, and a fairly stable condition was established. This 

 initiated perhaps the most interesting episode in the long lake 

 history — the beginning of glacial Lake Algonquin, the largest 

 of the glacial lakes and the last to be controlled by the ice 

 sheet. Up to this time the important lakes were in the Erie 

 and connecting basins; from now on the northern lakes be- 

 come important. 



Early Lake Algonquin; Lake Tonawanda 



The early Lake Algonquin (Figure 11) occupied only the 

 southern part of the Huron basin. The outlet at Port Huron 

 discharged its waters southward into Lake Erie, thence along 

 the ice front in the Ontario basin, past Syracuse and down the 

 Mohawk valley to the Hudson. Correlative with it were 

 lakes Chicago and Duluth in the west and Lake Tonawanda 

 in New York. When the ice front withdrew back of the 

 Niagaran escarpment and the waters in the Ontario basin be- 

 gan to lower, a broad shallow lake was left for some time, 

 stretching for fifty miles east of Buffalo, New York, and eight 

 or ten miles west of the present location of Niagara Falls. 

 Tonawanda Creek now flows on the bed of this short-lived 

 lake which wc know as glacial Lake Tonawanda. 



The waters of Lake Duluth reached Lake Chicago by flow- 

 ing southward from near Marquette, Michigan, through the 

 rocky channel now used by the short northward-flowing Au 

 Train River and the longer southward-flowing Whitefish 

 River, having abandoned the higher western outlet to St. 

 Croix River. Lake Chicago still used the Chicago outlet, via 

 the Des Plaines-Illinois-Mississippi rivers. The ice later with- 

 drew from the high lands west of Alpena, Michigan, and 



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