134 GEOLOGY OF OHIO.. 
shore and shoals which formed the margin of the great inland sea that 
once filled all the basin of the lakes. 
In the northern part of the county the Drift deposits are generally 
of so great thickness as to cover and conceal the underlying rocks. 
Wherever exposed to view, the rock surface is found to be planed and 
grooved by glacial action, and usually the overlying clay may be desig- 
nated as a bowlder clay, since it contains masses of rock derived from 
neighboring sources, with smaller and usually scratched and worn frag- 
ments brought from distant localities. This clay is unquestionably the 
material ground up by the great glacier which once covered Northern 
Ohio, pushed forward by its advance, and left in an irregular sheet upon 
the rocky foundation in its retreat. In some places the clay is finer, 
without gravel or bowlders, and is accurately stratified by the action of 
water. 
Immediately beneath the soil, or projecting above the surface, are 
found many transported bowlders, frequently of large size, composed of 
granite, greenstone, and other crystalline rocks, evidently of foreign ori- 
gin, and apparently derived from the highlands north of the great lakes. 
These bowlders are rarely found deeply buried in the Drift, and, as I have » 
elsewhere shown, must have been floated by icebergs from their place of 
origin, and dropped into their present position. Some of the superficial 
gravels which overlie the bowlder clay seem to have been transported by 
the same agency. 
As a whole, the soil of Portage county is productive, and although, from 
its tenacious character, and the dense growth of forest by which it was 
covered, it has required much patience and labor for its subjugation, this 
task has been well and thoroughly performed by the intelligent and in- 
dustrious population into whose possession it came; and it has repaid 
their efforts by a constant and generous support through the last half 
century. . 
In common with the other portions of the great divide on which Por- 
tage county is located, its rolling surface forms numerous local basins, 
many of which have been, and some still are, occupied by lakes. Of 
these lakes, West Pond, Brady’s Lake, and Lake Pepin in Franklin, 
Mud Lake, Sandy Lake, and Muzzy’s Lake in Rootstown, and Fritch’s 
Pond in Suffield, may be cited as examples. These lakes are supplied by | 
springs which flow through the Drift gravels, and their water is usually 
clear and pure; they contain great numbers of fine fish, and are also in- 
teresting and beautiful features in the scenery. Some of these basins, 
formerly occupied by water, have been gradually filled up by the growth 
