498 GEOLOGY OF OHIO. 
being monotonous by the shallow basins of the Stillwater and Green- 
ville Creeks, the frequent picturesque kames, and such other variations 
as are due to local causes! Occasionally, however, striking evidences are 
observed upon the underlying rocks of a wonderful erosive power, but, 
being covered on an average of probably one hundred feet of drift, little 
of the truth is manifest upon the surface contour of the country. It is 
true, the southern part of the county is in many places undulating and 
hilly, but it is evidently the result of the last submergence, and such 
agencies as are now at work ail over the State. 
Contrary to what one would at first suppose, the summit ridge nowhere 
presents a prominent and rugged outline. Being subjected to the denud- 
ing and erosive influences of past ages, it has become a broad, rounded belt 
of high land. Its varied alkaline clays have been distributed over the. 
low, moist lands of the Stillwater and Wabash, supplying the black, 
loamy soil with many of the necessary elements of productiyeness, and 
ameliorating the former irregularities of the country. Yet it still stands, 
marking the southermost shores of the northern lakes, a prominent fea- 
ture in the topography of the State. 
The highest land, manifestly, is found in the north-western part of the 
county, about the region of the divide. The highest altitude accurately 
known is a little north of Union City, being six hundred and sixty-five 
feet above low-water mark in the Ohio River at Cincinnati. On the 
summit ridge between Stillwater and the Wabash, the land has an eleva- 
tion of six hundred and thirty-five feet above the same point. The 
county line between Mercer county and Darke is six hundred and thirty- 
four feet, though there are other points about this locality which possibly - 
attain an altitude'of seven hundred feet. At Greenville we descend to 
about five hundred and ninety feet; and still farther south, at the county 
line between Darke and Preble, in Harrison township, we descend to five 
hundred and fifty-one feet. Ithaca, in Twin township, has an elevation 
of five hundred and fifty-seven feet above the Ohio. But the lowest land 
is probably to be found along thé bottom of Greenville Creek, in Adams 
township, where five hundred and twenty feet marks the altitude, and 
five hundred and forty feet the elevation of the neighboring bluffs or 
kames. The Ohio River being one hundred and thirty-three feet lower 
than Lake Hrie, these elevations must be lessened by that amount 
when compared with surface level of the lake. This would make 
the highest land about five hundred and sixty-seven feet above Lake Hrie, ,. 
or about one thousand one kundred and thirty-two feet above the level of 
the sea. : : . 
In regarding the surface features, it is noticeabke that but one remnant 
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