34 GEOLOGY OF OHIO. 



many years. It contains so little iron that the ware made from it is 

 white, or cream color. A similar clay at Miamisburg, supposed by 

 Prof. Orton to be of the same age, has been quite extensively used for 

 paint. A like deposit in the valley Drift at Cincinnati has been used 

 in forming concrete for the bottom and sides of the new reservoir. Every 

 thing indicates that this is a lacustrine deposit, that is, that it accumu- 

 lated at the bottom of a body or basin of fresh water. It is probable that 

 a precisely similar clay is now being deposited in Lake Geneva by the 

 milky water that flows from the glaciers. We may even carry the anal- 

 ogy further, by supposing this to be the very finest portion of the bowl- 

 der clay, which, stretching over the northern divide, was washed away 

 by shore waves and draining streams, and was deposited in the still 

 waters of the gulf or bay formed by the valley of the Ohio in its last 

 submergence. The yellow clay, abounding with gravel, and containing 

 occasional bowlders, which overlies the Forest Bed, and is more generally 

 the surface deposit of southern Ohio, is evidently the more immediate 

 and coarser product of the action of the in-coming flood, and copious 

 drainage from the north upon the ancient forest-covered land, of which 

 the sub-soil was the bowlder clay. So far as yet observed, there is no 

 satisfactory proof that an ice-sheet passed over the State of Ohio after 

 the accumulation of the old Forest Bed. The yellow clay under consid- 

 eration is quite different from the blue bowlder clay which lies beneath it 

 and the Forest Bed; and it seems scarcely possible that it could have been 

 spread by glaciers, and the Forest Bed and bowlder clay be left so intact 

 over large areas. I would rather ascribe it to the action of water ; but 

 calling to the aid of that water the icebergs that we know floated on 

 the surface of the inland sea, and, in the flooding of the Ohio valley, 

 passed over the summit, or through the gaps of the divide, and scattered 

 gravel and bowlders along their route in the country farther south. 



If, as seems probable, the stratified sediments which once partially 

 filled the immediate valley of the Ohio, and now form terraces like 

 those at New Richmond and Lawrenceburg, belong to the same epoch 

 with the upland Drift of southern Ohio, it would appear that when the 

 Forest Bed accumulated the continent was somewhat higher than now, 

 and the Ohio flowed at a lower level; and that during the subsequent 

 submergence the later Drift sediments were deposited over all the irregu- 

 larities of the surface. 



In the basin of the great lakes, the upper portion of the Drift series is 

 not quite so distinctly marked as in the valley of the Ohio, perhaps for 

 the reason that in the descent of the water line of the inland sea nearly 

 every portion of the slope which formed the southern boundary was 



