612 GEOLOGY OF OHIO. 



the surface of the deep Drift beds by which the valley is filled. The 

 Drift in the vicinity of Cynthiana often exceeds fifty feet in depth, and 

 the origin of the great excavation which has here been effected must be 

 sought in the Glacial epoch, or in pre-glacial times. 



Two of the tributaries of Sunfish Creek, viz., Chenoweth's Fork and 

 Morgan's Fork, are of considerable size, and have wrought out quite im- 

 portant valleys for themselves. 



The tributaries of Beaver Creek are of much less importance. 



besides these, there are but few streams in the county that have effect- 

 ed modification enough in the surface to deserve especial mention. The 

 most important of those that remain are Camp Creek, Peepee Creek, and 

 Crooked Creek, all of which are upon the western side of the Scioto. 



The tributaries of the Scioto on the eastern side of the valley, with the 

 single exception of Beaver Creek, already named, are of much less ex- 

 tent. None of them reach back from the river more than five or six 

 miles. At that distance, at least, they reach the high lands, from which 

 they descend very rapidly to the river. They are fed by no generous 

 spring 3 , and find their principal office in the removal of the superfluous 

 rain-fall. 



The surface of the county has never been covered and modified by the 

 deposits of the Drift as the areas to the northward have been. It pre- 

 sents, therefore, all the peculiar features that a country exposed to the 

 wear and waste of atmospheric agencies for tens of thousands of years 

 must show. It is easy to see what was the original condition of this 

 area. It consisted of a plateau, gently sloping to the east or south-east. 

 The western boundary of the plateau stands more than one thousand 

 three hundred feet above the sea. The elevation at the middle line of 

 the county was at least one hundred feet less. Only limited portions of 

 the old plateau remain. The extent and conformation of these old rem- 

 nants vary very much in different sections of the county, depending on 

 the geological formations in which they severally occur. On the ex- 

 treme western side of the county, where four hundred feet of easily 

 eroded shales overlying Upper Silurian limestones form the surface, the 

 remnants are of small extent, and occur for the most part as conical 

 hills, the shales having been swept away from broad valleys to the 

 limestone floor. These conical hills of denudation, when seen from the 

 limestone terraces of Highland county, fifteen or twenty miles to the 

 westward, present more the appearance of mountains than any other 

 elevations in the State, and are locally known under this designation. 



Passing eastward and southward, we find the solid courses of the Wa- 

 verly series constituting the original surface, and, as a consequence, 



