SURFACE GEOLOGY. 33 
our Drift deposits, the Forest Bed represents a great lapse of time. The 
advance of a forest growth over the barren Drift area must have been 
slow, and much time was certainly required to form the distinct sheet of 
carbonaceous matter which we now find. The climate of the State, at 
that period, must have been cold and damp, as the glaciers were still 
near, and the drainage from them which filled the water basin was icy 
cold. 
In the Forest Bed of the valley Drift we find quite a number of plants 
of the species now growing in the same localities, and such as could not 
have grown there had the climate been much colder than now, but the 
deep valley would have been warmer than the uplands; and, as has been 
already stated, it is not certain that the old soils of the valleys and the 
highlands are of the same age, though both belong to periods when the 
physical condition of the country was quite different from the present. 
Further investigations, following up the suggestions and conjectures now 
made, will undoubtedly result in the perfect elucidation of this interest- 
ing chapter on the complicated history of the Drift. 
I should not omit to mention that a stratum of bog iron ore accom- 
panies the old soils in both the valley and upland Drift beds. 
DRIFT OF THE TERRACE EPOCH. 
The materials which overlie the Forest Bed, and which form the upper- 
most members of the stratified Drift deposits, are clearly the product of 
a wide-spread submergence of an immense area in the Western States 
which had before been dry land. In a great number of instances in 
southern Ohio, where the Forest Bed is present, the materials overlying 
it have been penetrated in water wells, and their character has been 
accurately determined. For the purpose of showing what these strata 
are, I quote again, in part, the general section of the upland Drift of Cler- 
mont county, as described by Prof. Orton (Vol. I, Part I, p. 440): 
No. 1. Surface clays, generally white, sometimes blackened by swampy 
conditions yemtireliyiree irom! QvAVE)......cc.0. secescocs cecoesese cones sacs 1 to 8 feet. 
No. 2. Yellow clays, abounding with gravel, with occasional bowlders, often 
constituting the surface instead of 1. Thickness seldom ex- 
COC MIM ee eee nde Man Ey acl lenala’s uuu eer safiotiaa daaaicek lh degamend cummete sexe 10 feet.. 
No. 3. Forest soil and bog iron ore. 
No. 4. Blue bowlder clay, or hard-pan. 
The white clay of the above section is a somewhat localized deposit,. 
but one that is spread over a wide area. In Clarke county it is called 
the Springfield clay, and has been worked as a brick and tile clay for: 
3 
