136 | GEOLOGY OF OHIO. = 
localities. In some places, as near Campbellport, the Drift deposits are 
largely made up of angular or little-worn fragments of sandstone, torn 
from their beds in the immediate vicinity; while in places remote from 
such outcrops of the harder rocks, the stones contained in the clay are 
small, much worn, and many of them are composed of granite, etc., 
brought from the region north of the lakes. 
On the highlands the gravel beds referred to above rest sometimes on 
the bowlder clay, but perhaps oftener on the underlying rock, showing 
that the causes which produced the accumulation of gravel generally 
removed all the clay. ‘Where the gravel beds overlap the bowlder.clay, 
the materials which compose them seem to have been washed back from 
the higher grounds. It will be noticed that the pebbles in the gravel 
beds are well rounded and often irregulary stratified, while those found 
in the bowlder clay are sub-angular, scratched, and worn, but rarely 
rounded. It is evident, therefore, that the gravels have been subjected 
to a triturating action quite different from that exerted by glaciers on 
the materials which they move. The facts show, further, that water, either 
in shore waves or in river currents, has been the agent by which the 
pebbles of the gravel have been rounded; and as it is difficult to conceive 
of any currents which could leave beds and hills of gravel such as are 
found along the divide between the waters of the Lake and the Ohio, I 
have been led to consider these deposits as the effect of shore-waves, 
when the Lake basin was filled to this height, on the bowlder clay and 
other Drift material which once covered the underlying rocks. It is pos- 
sible, too, that the drainage from the glacier, when it filled the lake 
basin and was melting along its southern edge, contributed to the wash- 
ing of the clay and the rounding of the pebbles. In this view the gravel 
hills and sheets which cover so much of the great divide which crosses 
the State may be compared to the terminal moraines of existing glaciers, 
but in no moraine of which I have any knowledge are the pebbles and 
bowlders nearly so well rounded as in the deposits under consideration ; 
and I am sure all who will carefully examine these will agree with me 
that free and Swift, moving water, in large quantity, has been the chief 
agent in producing the phenomena exhibited. Along certain lines lead- 
ing from the summit of the watershed to the Ohio, both east and west of 
Portage county, there are belts of gravel and bowlders, which mark, as I 
eonceive, broad and long-existing drainage channels, by which the 
plus water of the lake basin flowed through certain waste-weirs cut in 
the watershed, escaped southward, but the gravel hills of Portage county 
ean hadly be referred to such a cause. 
