THE PREGLACIAL DRAINAGE OF OHIO. 55 



channel, only lo miles west, over the horse-back divide at 

 Lodi. 



Such a channel in width and depth, could not have been pro- 

 duced by drainage from the north, for, it is only 12 miles to the 

 rock crest above Medina city, and but six miles to the north 

 and south divide between Chatham and Lafayette townships. 



It was on the foot hills of the east face of this divide that 

 the two wells — noted in the early part of this paper — were drilled 

 to rock, at the respective depths of 149 and 125 feet; they are 

 4^ miles apart, and, joining- them with the Medina city foot hill, 

 4^ miles north, they mark the eastern extension of the Waverly 

 as a surface rock, from Le Roy to Medina, a distance of nine 

 miles. Opposed to this headland of Waverly I find the declin- 

 ing face of the last projection of the Coal Measures from Sharon 

 to Seville, where the quarries of Carboniferous conglomerate 

 are worked from the western face of the hill, and it was between 

 these diverse and opposing faces that the primitive channel ran 

 into that of Rocky river. 



I must now search for a cause of sufificient magnitude to 

 convert the drainage system described, into that of the present; 

 a conversion that has created a new topography for a large part 

 of the State of Ohio. 



When the glacier passed from the soft shale bed it had 

 plowed out for Lake Erie to lie in, it met two mountainous ob- 

 stacles of greater, and yet unequal resistance; viz: the Coal 

 Measure hills and the Waverly plateau, each still rising to the 

 height of 700 feet, with the pre-glacial channel, over which now 

 runs the Rockv river exactly between them; seven miles east of 

 Rockv river, opened the wide mouth of the Cuyahoga, that 

 drained the northwest face of the Coal Measures: a cross section 

 of these, from east to west, through the center of Cuyahoga 

 county shows (according to Prof. Newberry in Vol. I, Geolog- 

 ical Survey) the pre-glacial bed of Rocky river to be 3 miles wide 

 and that of the Cuyahoga 4^ miles, with the intervening Coal 

 Measure projection only 7 miles. Now 14 miles west of Rocky 

 river comes down across the Waverly the broad trough over 

 which now flows Black river, and all these wide pre-glacial chan- 

 nels worn down into the Erie shale, below the Lake's present 



