ANCIENT GLACIERS. 95 



marked line of moraine hills, formed probably as termi- 

 nal deposits in the later stages of the Ice age, runs from 

 near the eastern end of Lake Ontario to the Georgian 

 Bay, passing south of Lake Simcoe. 



The Mississippi Basin. 



The physical geography of the glaciated region north 

 of the Ohio Eiver is so much simpler than that of New 

 England and the Middle States, that its characteristics 

 can be briefly stated. Ohio, Indiana, and Illinois are cov- 

 ered with nearly parallel strata of rock mostly of the Car- 

 boniferous age. In general, the surface slopes gently to 

 the west; the average elevation of Ohio being about a 

 thousand feet above tide, while that of the Great Lakes to 

 the north and of the middle portion of the Mississippi 

 Valley is less than six hundred feet. The glacial deposits 

 are spread in a pretty even sheet over the area which was 

 reached by the ice in these States, and the lines of mo- 

 raine, of which a dozen or more have been partially traced 

 in receding order, are much less clearly marked than they 

 are in New England, or in Michigan, and the States far- 

 ther to the northwest. 



The line marking the southern limit attained by the 

 ice of the Glacial period in these three States is as follows : 

 Entering Ohio in Columbiana County, about ten miles 

 north of the Ohio Eiver, the glacial boundary runs west- 

 ward through New Lisbon to Canton in Stark County, 

 and thence to Millersburg in Holmes County. A few 

 miles west of this place it turns abruptly south, passing 

 through Danville in Knox County, Newark in Licking 

 County, Lancaster in Fairfield County, to Adelphi in Ross 

 County. Thence bearing more westward it passes through 

 Chillicothe to southeastern Highland County and north- 

 western Adams, reaching the Ohio River near Ripley, in 

 Clermont County. Thence, following the north bank of 



the Ohio River to Cincinnati, it crosses the river, and after 



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