LORAIN COUNTY. 209 
county is immediately underlain by beds of clay, which form part of the 
series of Drift deposits that cover so much of Ohio and the adjoining 
States. Beneath these the surface of the underlying rocks—wherever 
hard enough to retain such markings—is found planed, grooved, and 
striated, evidently by ice which formed part of a great glacier that filled 
the lake basin and flowed over it, reaching as far as the Ohio. This 
glacier was for ages moving from the north southward, and as it rested 
with immense weight on the rocky sub-strata of the country, by the aid 
of sand and gravel which accumulated beneath it,it ground down the 
rocks over which it moved to nearly a plane surface, and grooved 
and scratched them just as glaciers now do the rocks which they 
traverse. The materials excavated and ground up by the ice-sheet were 
pushed along by it in its motion and thrust out at its margin, where 
they remained to form a “moraine,” or were washed away by the water 
formed by the melting ice. Hence it is apparent that no considerable 
accumulation of matter of any kind could take place under the gla- 
cier. But we find the glaciated surface often deeply buried under beds 
of clay, sand, and gravel, which must have been deposited there after 
the retreat of the glacier. These sheets of superficial material are called 
the ‘Drift,’ from the fact that they have ben generally transported 
long distances from their place of origin. In the northern part of Ohio 
the Drift deposits are usually clay—stratified or unstratified—with more 
or less sand and gravel, and at the surface large transported bowlders. 
Of this series the lowest is unstratified clay, thickly set with frag- 
ments of shale, and with some small, usually striated, bowlders of crys- 
talline rock, brought from the region north of the lakes. This deposit 
is called the bowlder clay, and is the direct product of the grinding 
action of the glaciers upon the shales, limestones, etc., which have been 
excavated in the formation of the lake basin. As the glacier melted 
away and retreated northward, this bowlder clay was left in a somewhat 
irregular sheet along its margin, and we still find it covering the rock 
surfaces over most of Lorain county, where a basin of water took the 
place of the ice. From this were deposited sheets of fine clay, frequently 
beautifully stratified, and without pebbles or bowlders. Hence we often 
find the lower bowlder clay overlaid by laminated clay, but the two 
varieties blend together and have been included in the general term 
“rie Clay.” The bowlder clay is also frequently called hard-pan. It is 
blue in color, and exceedingly compact and tough. Sometimes it is yel- 
low or reddish, from the oxidation of the iron it contains; and this is the 
prevailing color of the stratified clay. 
The sand and gravel which sometimes overlie the clays were deposited 
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