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 old quarry, as well as of Halysites. 



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, are in 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, Favosites, and Syringopora. 



At the falls of Ludlow Creek, attempts were made to open a quarry, a 

 few years ago, to obtain building stone, particularlv 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 oi 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 ae 

 to any exposure where it belongs. 



The Blue Lwiesfone 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 Charlee- 

 town cliffs and then at Col. Woodward's. On the same line of cliflfs, 

 further south of the National road, the blue shale is manufactured into a 

 good article of drain tile by Mr. Mark Allen. It is to be seen in the rail- 



