Science, Geology and Physics 



Among the conditions which might cause the Niagara river to 1903 

 vary from its present size, only one would produce a great and 

 long continued diminution of the river, so giving for a large part 

 of its history only very slow erosion of the gorge. This hypotheti- 

 cal factor in our problem, which has been assumed by Gilbert, 

 Spencer, Taylor, and Hitchcock, to considerably prolong the 

 time of the gorge erosion, is the diversion of the outflow from 

 the basins of the three lakes above Lake Erie, then confluent 

 and forming the glacial Lake Algonquin, to forsake its present 

 course and pass eastward from Georgian Bay, at first by the 

 way of Lake Simcoe and the Trent river to Lake Ontario, and 

 later by Lake Nipissing and the Mattawa river to the Ottawa. 



But differential elevation of the land from its late glacial or 

 Champlain depression here, as on the area of Lake Agassiz, 

 which is now drained by the Red River of the North to Lake 

 Winnipeg and thence by the Nelson river to Hudson bay, took 

 place as soon as the land was unburdened by the glacial retreat. 

 This northward uplift was in progress while yet the ice barrier 

 remained farther north and northeast, holding in succession the 

 glacial lakes Warren and Algonquin, besides several earlier and 

 smaller glacial lakes which became merged in Lake Warren, on 

 the upper part of the St. Lawrence river basin. In the areas of 

 Lake Agassiz and of the Laurentian lakes alike, the uplift was 

 nearly completed during the existence of the glacial lakes, as is 

 known by the almost undisturbed horizontality of the latest and 

 lowest glacial lake beaches. Finally Lake Algonquin, by the 

 northeastward land elevation, became divided into its successors. 

 Lakes Huron, Michigan and Superior. 



Instead of the hypothesis of a long continued eastward out- 

 flow from Lake Algonquin, my studies convince me that the 

 Trent and Mattawa outlets were occupied successively during 

 only a brief time, or, more probably, that these outlets were 

 obstructed by the receding ice-front until after the land there had 

 risen from its Champlain depression to such altitude that the St. 

 Clair and Detroit rivers continued to be constantly the outlet 



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