436 GEOLOGY 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 Tentaculies 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, 
so 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 have 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 excavated. 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 i 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, 
so far as observed, nearly, coincided with the direction of the present 
Anderson’s Fork. Doubtless where the bottom of Andergon’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 accumulations were 
madesubsequent 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 
