14 Bulletin of Laboi'atorics of Doiison Unk'crsity. [Voi, xii 



comparatively quiet waters of the glacial lake, presented shoals 

 for the stranding of floating icebergs. As one of these would 

 be melted another would be caught, and so gradually the col 

 received its accumulation of boulder clay. Another specially 

 noticeable feature of the region is the sudden change from the 

 broad, shallow valleys with gently sloping hill sides West of the 

 main divide to the deep ravines and abrupt slopes that one finds 

 immediately upon crossing to the eastward. In travelling from 

 Bladensburg toward Coshocton we found first a fine rolling 

 country, excellently adapted to cultivation, which extended up 

 to the very brow of the divide. Then suddenly and without 

 the shadow of a gradation in passing from the one character to 

 the other we found ourselves in the midst of as rough and hilly 

 a region as is to be seen in the state. Of course the valleys 

 have not the depth that is to be observed down nearer the Ohio 

 River, but they are just as numerous and broken, with just as 

 little evidence of any leveling influence due to glaciation. 



Although the glacier itself, and probably the great major- 

 ity of the icebergs, did not extend beyond the barrier of the 

 great divide, there is abundant evidence that the water level of 

 the glacial lake was maintained beyond it for some time. Near 

 the tops of the hills along many of the valleys are to be seen 

 well defined beach marks that can be accounted for in no other 

 way so readily as by supposing that they were formed by the 

 action of the surf before the great cols down the Muskingum 

 and Ohio Rivers had been cut away sufficiently to lower the 

 level of the glacial waters. The reader is not to understand 

 that no glacier worn materials are to be found East of the di- 

 vide. They exist there in abundance, but very few of them on 

 the tops of the hilis, or rather cols, as is the case to the West. 

 Practically all such debris is found in the bottoms of the old 

 valleys where it has been deposited by the water coming from 

 the glaciated region during and after the cutting down of the 

 old cols. After the filling in this way of the main axes of the 

 new drainage systems, the tributaries of these s}'stems would 

 fill in the natural course of events with the sediment from their 

 own drainage. 



