234 THE CANADIAN NATGHALIST. [Vol. X. 



the Maiiouiu^i; river, reversed, into the state of Ohio, to near the 

 tiources of the Grand and Cuyaho^ra river.*-. Hence Mr. Carll 

 did not continue its course, on the map, bui from the study of 

 the levels and character of the country, as described by the 

 Oeologicai Survey of Ohio, I have connected it with the Grand 

 river of Ohio, us represented on my map. In addition to this 

 drainage I have pointed out the probability* that the Mahoning 

 and upper Ohio, with the Beaver (reserved), Mahoniu<>- (reserved) 

 iind Grand (of Ohio) rivers formed a nearly straight valley, from 

 the western side of the mountains of Virgini i to Lake Erie. 



Thus we find three large areas now flowing southward formerly 

 ■emptying into Lake Erie basin. 



The deepest portion of Lake Erie is between these ancient 

 river mouths and the ancient dehouchtiutut of the Erie drainage 

 by the Grand river of Ontario, as described in tjjese pages. 



Thus we have shown a consecutive system of drainage of the 



former waters of the buried channels into Lake Ontario, and 



thence running along the foot of the submerged escarpment of 



the latter lake to its eastern end, receiving the Genesse and other 



.large rivers along its course. 



Not only is the Dundas valley a deeply buried channel, but 

 nearly all the streauis that enter Lake Ontario are flowing over 

 more or less deeply buried channels. 



Origin of the Lowkr Great Lakes. 



All of the chain of Great Lakes of North America are excava- 

 ted principally out of the more ur less shaly almost horizontal 

 rocks of the various basins. They are all valleys of erosion 

 •(excepting perhaps, a portion of Lake Superior.) The erosive 

 action of the atmospheric agencies would tend to wear the coun- 

 try into uudulutiug basins, — for only such are the bottoms of the 

 ^reat Lakes. It is true that slight geological undulations may 

 have determined the position of the lake-basins. The basins of 

 Lakes Michigan, Huron and Ontario, especially, are traversed 

 by long sub-lacustrine valleys resembling those of large rivers, 

 and bounded by escarpments, which rise abruptly several hundred 

 feet high. The description of the lake bods — the prob ible Pre- 

 glacial outlets of Lakes Superior and Michigan (discharging 

 their waters to the Mississippi valley] ; the outlet of Lake Huron 



* See Proc. Am. Phil. Sue. XIX. 108. 



