478 GEOLOGY OF OHIO. 
ara. The Niagara extends on a horizon throughout the county, from the 
upper parts of the abrupt cliffs mentioned, to the Drift above. The falls 
and blufis on Greenville Creek, near Covington, are in the Niagara. 
The upper surface of the Niagara is made uneven by the wearing away 
of portions of it by the action of the Drift period. When it was formed, 
it extended over the entire county in a bed of a thickness, no doubt, 
much greater than the thickest portion which remains. How much of 
its o iginal thickness was abraded by Drift action, we have no means of 
ascertaining. But asmall part remains of that which formerly existed. 
The water-courses have worn off both Niagara and Clinton. In some 
places all the Niagara is abraded, and the Clinton is the surface rock, 
as at all horizons below that of the top of the cliffs named as composed 
of Clinton. In other places the Niagara is but a few feet thick, as at 
the Piqua quarries. At Kerr’s quarry, in ihe south, at those in Ludlow, 
Panther, and Greenville creeks, and at the lime-kilns, north of Clayton, 
the formation remains of considerable thickness. 
The fragments of the upper beds of Niagara which escaped the denud- 
ing «fiects of the Drift period, are of a seft, porous rock, highly fossilifer- 
ous. This pertion of the formation makes building lime of the best 
quality. At Brant, in the south, and at Clayton, in the north, exposures 
of this upper portion of the syetem remain, and a large quantity of lime 
has been manufactured and commands the highest price in the market. 
Practically the quantity is sufficient for all demands likely to be made | 
upon it. The lack of transportation hinders the development of the re- 
sources of the localities named for lime-making. 
The quarried stone of this county comes mostly from the Niagara. I 
place the Piqua stone in the Niagara. Iam aware that it is in lithological 
characters anomalous when compared with this formation as developed in 
this section. It isequally so with the Clinton. Itisextremely local and 
lies, without any transitional strata, immediately upon undoubted Clinton. 
It may represent the transition of Clinton to Niagara. It isa fine-grained, 
mostly sedimentary stone, without a large proportion of fossils. It preb- 
ably thins out in all directions. It dresses extremely well, and isa stone 
of rare excellence. The Clinton underlies this stone, and has an uneven 
upper surface. This unevenness consists of mound-like elevations, some- 
times twenty feet in diameter and four feet high in the center. Upon 
these little mounds, composed of species of branching corals, the Piqua 
stone lies, conforming to its unevenness of surface. I have spoken of 
the worn surface of this stone by the action of the Drift. The Drift has 
removed the Covington type of stone from the top of this at Piqua. 
Passing to the other quarries in the Niagara, for a connected view of 
