480 GEOLOGY OF OHIO. 
renders the quarrying of it. difficult, and makes it necessary, before it 
can be used for masonry, to cut it on all sides. The lower strata are used 
for fire-stones and hearths, and endure the greatest heat of the ordinary 
fire-place, as lining stones, for many years. 
At Mr. S. D. Green’s, one mile east of Lost Creek, the Clinton appears 
about twenty feet above the bed of the creek, and attains a thickness of 
some thirty feet on his farm. While the lower exposures are composed, 
in a large measure, of fragments of encrinites, the upper is made up of 
various species of coral. At the highest exposure, on Mr. Green’s farm, 
is a very good quality of stone for lime. Very fine specimens of 
Syringopora can be obtained in the oid quarry, as well as of Halysttes. 
Between Troy and Piqua the new Troy hydraulic was cut for several 
hundred feet through the solid Clinton formation. Near this point the 
same stone may be seen exposed on the river bank. 
The lime-quarries, on the south of Piqua, arein the Clinton. The lime 
has nearly the same properties as that burned in Mr. Brown’s quarries. 
Here the Clinton seems to be but a mass of fossils, mostly corals of the 
genera Stromatopora, Halysites, Havosites, and Syringopora. 
At the falls of Ludlow Creek, attempts were made to open a quarry, a 
few years ago, to obtain building stone, particularly of a fine quality. 
It is called the “marble quarry.” The stone is of a good quality, 
crystalline, even-grained limestone, which takes a fine polish; but its 
hardness, and the frequent fractures and unevenness of strata, made it 
unprofitable as a business operation. I have given enough instances of 
the occurrence of this stone. Any one observing with care the horizon 
of each formation, and the character of the stone, can readily decide as ~ 
to any exposure where it belongs. 
The Blue Limestone of the Cincinnati Group.—I shall attempt to do nothing 
more than indicate the horizon of this group, and refer the reader to 
the volumes of these reports in which this formation is specially treated of. 
The Blue Limestone comes in below the base of the Clinton. In some 
places heavy beds of shale intervene. It will be observed in the sections 
given, that various transitional strata exist between this formation and 
the next above. Whether these represent formations which are more 
distinctly developed in other localities, I do not undertake to decide. 
The Blue limestone may be regarded as practically, in this county, 
coming in next below the Clinton. The Clinton is succeeded downwards 
by blue or red shales. These may be observed at the base of the Charles- 
town cliffs and then at Col. Woodward’s. On the same line of cliffs, 
further south of the National road, the blue shale is manufactured intoa 
good article of drain tile by Mr. Mark Allen. Itis to be seen in the rail- 
