Geography of Ohio 185 



well understood, deposited gravel and silt, which would be found 

 only where streams had been. . 



In time all these puzzling observations came to be understood, 

 Now% within the area that w^as glaciated one seldom meets a 

 citizen who has not some knowledge of the glacial period. 



Margin of the ice sheet. Nearly three-fourths of Ohio was covered 

 by the ice sheet. The front of the ice coincided roughly with the 

 rugged topography of the coal regions. On the eastern border of 

 the state, the glaciated area terminates about ten miles north of 

 East Liverpool. Its margin runs almost directly west to Canton ; 

 thence it has a southwest direction to Millersburg, in Holmes 

 County. From Millersburg, the ice began to turn more nearly 

 west, to approximately the eastern border of Knox County. 

 From this point, for several miles, the general front of the glaciated 

 area has a north-south direction. But upon entering Peny 

 County, it again bears to the southwest, crossing the Scioto River 

 near Chillicothe; from Chillicothe the same general direction 

 continues to the Ohio river, in Brown County. From this point 

 westward, nearly to Cincinnati, it reaches a few miles into the 

 area of Kentucky. 



This glacial boundary in Ohio is but a segment of the margin 

 of the great ice sheet that covered so much of North America. 

 In the western part of the Mississippi basin, the general front 

 had a northwest-southeast direction, except near the Rocky 

 Mountains, where it trended more nearly east-west. About one- 

 third of Montana was ice-covered. The southwestern corner 

 of North Dakota was beyond the ice sheet, and the western half 

 of South Dakota was not glaciated. From this point, the front 

 of the glacier bore almost directly south, covering the eastern 

 end of Nebraska, then turning to the east; only a small area of 

 the northeast corner of Kansas was glaciated; thence the ice 

 margin bore slightly south of east, crossing the Mississippi River 

 a few miles north of Cairo, 111. In southern Indiana, a triangular 

 shaped area, its base following the Ohio River north to Madison, 

 was not glaciated; a short distance north of IMadison the ice 

 crossed the river; thence, its front trended slighth" north to the 

 vicinity of Cincinnati. 



The northwest corner of Pennsylvania is also included in the 

 glaciated area, the ice-front passing northeastward into New 

 York State; it shortly bears southward again, leaving New York 



