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 bluffs on Greenville Creek, near Covington, are in the Niagara. 

 The upper snrface 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 original thickness was abraded by Drift action, we have no means of 

 ascertaining. But a small part remains of that which formerly existed. 

 The water-coursfis 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 the 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 efiects of the Drift period, are of a soft, porous rock, highly fossilifer- 

 ous. This portion 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 system 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. I am aware that it is in lithological 

 characters anomalous when compared with this formation as developed in 

 this section. It is equally so with the Clinton. It is extremely local and 

 lies, without any transitional strata, immediately upon undoubted Clinton. 

 It may represent the transition of Clinton to Niagara. It is a fine-grained, 

 mostly sedimentary stone, without a large proportion of fossils. It prob- 

 ably thins out in all directions. It dresses extremely well, and is a 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 

 etone 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 



