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 all 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 productiveness, 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 localitj' 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, lias an elevation 

 of five hundred and fifty-seven feet above the Ohio. But the lowest land 

 is probably to be found along the 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 Erie, 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 Erie, 

 or about one thousand one hundred and thirty-two feet above the level of 

 the eea. 



In regarding the surface features, it is noticeable that but one remnant 



