384 GEOLOGY OF OHIO. 



the glacier on the unmodified Drift along its foot when in the act of 

 retiring. They, however, may be attributed to the action of the water 

 of the Maumee, instead, upon the glacial Drift at the time of its deposi- 

 tion by the glacier. Its action, however, would be more likely to be 

 seen throughout the whole thickness of the Drift, and would not be over- 

 lapped by the hard-pan deposits as these laminations are seen to be near 

 their junction with the glacial clay. 



The surface of the Drift in various parts of the oounty has suffered 

 considerable denudation since the retirement of the glacier. The waters 

 of Lake Erie formerly covered the whole county, rising about 180 feet 

 above their present level. Their prevalence at that height is indicated 

 by the following phenomena : 



1st. The rock is laid bare in a great many places, and is wrought 

 into fantastic shapes, similar to the surface of rock now undergoing the 

 constant beating of the waves. Such water-worn rock is seen nowhere 

 in north-western Ohio except along the present lake shore, and at vari- 

 ous heights above it up to about 180 feet. 



2d. In the vicinity of these rocky outcrops, known as "limestone 

 ridges" in the Black Swamp, there are great numbers of bowlders of all 

 sizes, and usually of metamorphic rocks. They are thought to be the 

 remains of the hard-pan which at first covered uniformly the underly- 

 ing rock, the clay and sand having been washed out by the waves. They 

 usually lie immediately on the bare rock, and are most abundant round 

 the bases of the ridges. They are water-worn and rounded. 



3d. Deposits of fine sand, similar to the subaqueous bars and 

 beaches now forming about the shores of Lake Erie, are scattered over 

 the whole county, and seem to occupy all heights up to about 180 feet 

 above the Lake. They are seen on the elevated portions, that is, on 

 those portions which rise somewhat suddenly above the surrounding 

 level. Thus they follow, and almost mark out, the eastern border of 

 the Niagara area in the center of the county. These sandy deposits are 

 not only in the form of isolated knolls, having nuclei of the persistent 

 breccia of the Waterlime formation, but are sometimes so continuous 

 and regular as to have the name of ridges. Such ridges are met with 

 in all parts of the county, running in all directions ; and sometimes 

 roads have been located on them. The continuous ridge which passes 

 through the townships of Bloom and Perry, in the south-eastern part of 

 the county, is not one of lacustrine origin, but is believed to be of the 

 same nature as those long gravel ridges seen at higher altitudes in 

 north-western Ohio having the nature of terminal glacial moraines. 

 Yet it must have been submerged by the waters of the Lake in some 



