456 Geological History of the Lake Region. 



of lakes, 65 feet below the sea. Michigan is merely a great bay 

 lying off from the main line of drainage. It is obvious that the 

 present relative depths of the connected chain of lakes are incon- 

 sistent with their being merely the flooded sections of an old river 

 valley, for the bottom of Ontario, the lake nearest the sea outflow, 

 is 365 feet below the sea, and 600 feet below its own outflow into 

 the St. Lawrence ; the bottom of Superior, the lake furthest inland, 

 is 65 feet below the sea, and 527 feet below the bottom of Erie, 

 which intervenes, and no less than about 570 feet below the river- 

 bed outlet of Erie. 



A glance at the map will show how closely the watershed line 

 environs the great lake district. The lakes receive no long rivers, 

 and it is a mere narrow belt of land that drains into them, beyond 

 which the drainage goes north towards Hudson's Bay, south towards 

 the Mississippi, and east by the Ottawa. Several of the rivers 

 running into the great lakes have on the map a curious aspect of 

 continuity with the tributaries of the Mississippi system ; this is 

 especially noticeable in the case of the Wisconsin flowing into the 

 Mississippi, and Fox Eiver flowing north-east into Green Bay of 

 Lake Michigan. The same relation is observable between the 

 Wabash flowing into the Ohio, and the Maumee running into Lake 

 Erie ; and it is worthy of observation that the tributaries of the 

 Maumee are bent back in a direction rather ranging with the 

 direction of the confluents of the Wabash than with that of the 

 Maumee, with which their main course forms an acute angle against 

 tlie stream. If the lake area is a region of depression, it seems 

 possible that the extremities of the confluents of the Mississippi 

 may have been depressed towards the lakes, and the waterflow 

 diverted northwards without the old valleys being obliterated. 



We must set aside the view that the chain of large lakes is due 

 to glacial excavation; for Ontario, the deepest of the lakes running 

 east and west, is in lower latitude than Huron, the bottom of which 

 is 510 feet above that of Ontario, and there is no high ground about 

 Ontario from which ice could have originated as a preponderating 

 mass, capable of excavating Ontario 600 feet deep ; nor is there any 

 such mass of debris anywhere to be seen about the lake as would 

 represent such an excavation. 



New York State, bordering on Ontario, abounds with small lakes, 

 running north and south, between escars and drift ridges, evidently 

 of glacial origin, and which have nothing in common with the 

 direction or character of the larger lakes, which must be the result 

 of the subsidence of the area, bounded by their environing water- 

 shed, resulting in a fresh basin of drainage towards the Atlantic, 

 the former drainage of which was divided between the Mississippi 

 basin, Hudson's Bay, and the Ottawa. The contour of the land 

 surface north and south of the great lakes seems to indicate that the 

 subsidence of the containing area was subsequent to the glacial ex- 

 cavation of the numerous small lakes running north and south, and 

 it seems probable that the Niagara gorge, as well as the St. Lawrence, 

 down to its junction with the Ottawa River, are of post-glacial origin. 



