THE PREGLACIAL DRAINAGE OF OHIO. 71 



that it joined old Kanawha north of Dayton — probably in the 

 neighborhood of Piqua. 



The lower part of the Great Miami requires a few words of 

 explanation. There was a col at (F), just south of the village of 

 Miami. North of this Taylor's creek flowed north and emptied 

 into the Kentucky at (I). South of the col (F), a small ravine 

 joined the creek that flowed through the gap at North Bend, at 

 a point somewhere near Valley Junction (K). 



Having thus traced the former rivers and their tributaries, 

 and located the cols, so far as they are essential to the problem, 

 we are in a position to follow the steps by which the Ohio was 

 established. 



The Great Kanawha held its way across Ohio until the 

 glacier had advanced to that part of its valley which extended 

 farthest to the northward. For a time the waters may have 

 skirted the ice-front and recovered their natural channel farther 

 down ; but presently the valley was completely closed and the 

 imprisoned waters found no escape until they had reached the 

 level of the col at Madison (E). 



At this stage began the readjustment of drainage channels. 

 The principal stream at this time was, of course, the Kanawha. 

 How far it may have extended toward the north or the north- 

 west, we have no means of knowing ; but it was probably first 

 reached by the glacier at some place west of Ohio. Shut off 

 by this agent from its natural outlet, it turned back into the old 

 Kentucky, wherever their confluence may have been ; followed 

 that channel past Hamilton, Lawrenceburg and Carrolton and 

 was impounded by the col at Madison (E). If we may judge 

 from the nearly uniform level of the hills on either side of the 

 river there, up to the very edge of the cliffs which descend 

 steeply to the water, this point in the old watershed was but 

 little lower than any other along the crest. Whatever its eleva- 

 tion, the Kanawha was compelled to rise to its level. As a 

 result, a lake was formed which reached well up toward the 

 headwaters of every stream between the Kentucky river and the 

 Cumberland mountains on the south and to the eastern part of 

 Ohio on the north. It had to reach the level not of the bottom 

 of the gap, but of the highest flood of the torrents which poured 



