436 GEOIiOOY OF OHIO. 



sound at the stroke of the hammer, and seemed to be of the same material 

 as a drift-stone which I saw at Mr, Hegler's, on Herod's creek, in Ross 

 county, which contained Tentaculites in abundance. Formations in Clin- 

 ton county, which were formerly continuous, have been partially removed, 

 as on Cliff Run the Clinton formation is seen in its full thickness, while 

 excavations show that its continuity is broken to the east of this locality, 

 80 that the exposure of white limestone on Cliff Run is a mere island of 

 this kind of stone. 



Besides the wearing^ away of the general surface and the removal of 

 particular parts of formations, there were causes at work which hare ex- 

 cavated channels far below the general surface. Ice, in the form of 

 glaciers, is generally regarded as the means by which the denudation 

 above alluded to has been effected, and moving water has doubtless been 

 the instrument by which the deep channels have been e;xcavated. These 

 channels are only traced by observing the excavations which are made 

 for one cause or another, the sinking of wells, and borings for water. An 

 instance of this channeling is noticed in that region in Clinton county 

 know as the " Prairie," where it has been frequently observed that there 

 are places apparently forming a continuous line, where rock is not found 

 at any depth yet reached, although on each side it is but a short distance 

 to the undisturbed strata. This channel has not been thoroughly, but, 

 80 far as observed, nearly, coincided with the direction of the present 

 Anderson's Fork. Doubtless where the bottom of Anderson's Fork is the 

 bedded rock, the old channel was cut to one side or the other of that in 

 which the water flows at present. Connected with the fact of the exist- 

 ence of such deep drainage at a former period, is implied that the whole 

 country was at a much greater elevation above the sea than it is in 

 our time. 



THE DRIFT. 



The old channels became silted up, and other aceuroulations were 

 made subsequent to the period of denudation. The surface of the land 

 must have sunk down so as to be beneath the surface of the water. 

 Every indication points to water as the medium by which the deposits 

 were made. Upon the surface of the stone is everywhere found more or 

 less of loose material. The study of this material in both these counties 

 is full of interest. The Drift is composed of clay, with varying propor- 

 tions of sand and gravel, with occasional rounded blocks of granitic 

 rock, and with the remains of trees, and sometimes of other vegetation. 

 The greatest thickness of the Drift in our district is in Clinton county, 

 east of the "Prairie," where a deposit of over one hundred feet is found. 

 Whether the whole surface of the county was once covered as deeply as 



