354 CHARLES S. PROSSER 



Section of the J. W. Ruhl Quarry at Covington 



Thickness T mcK^ss 



No. Feet Inches Feet Inches 



ii. Cedarville dolomite. — Fairly massive, gray to 



buff, porous dolomite, with the characteristic 



lithologic appearance of the Cedarville. Cer- 

 tain layers contain abundant impressions of 



crinoid segments and parts of stems with an 



occasional cup coral. Rather infrequently 



more or less of the calcareous material of a 



crinoid stem is preserved. In the weathered 



wall are rather large holes in addition to the 



smaller ones which give it the porous structure. 



Near the base, Spirifer and other Brachicpod 



shells were noticed in association with crinoids. 



The upper 1 1 feet of this part of the quarry wall 



belong in the Cedarville, but on a wall farther 



south some 15 feet of Cedarville are shown. . . 11 o 26 5 



10. Springfield dolomite. — When weathered, buff, 



compact rock containing small holes, due to 



solution of crinoid fragments. Layers vary 



from 2 to 6§ inches in thickness; but the 



majority are 3, 4, or 5 inches thick. All of the 



zone is somewhat porous 2 6 15 5 



9. Chert zone containing 4 layers of chert. The 



rock is harder than in the zone above, denser, 



not so porous, and of slightly greenish-gray 



color. Pentamems oblongus Sowerby occurs in 



the second chert above the base as well as in the 



lowest one 2 10 12 11 



8. Ten-inch layer in which Pentamerus oblongus 



Sowerby is common 10 10 1 



7. Compact, hard rock, somewhat rough on the 



broken surface. Color gray; but of different 



shades, so that it is not uniform 1 8 9 3 



6. Hard, compact, light-gray rock in which holes 



are infrequent. Stylolites are frequent in the 



bedding planes of this part of the quarry wall 11 7 7 



5. Lithology of layer similar to overlying one. ..11 6 6 



4. Similar, but with a more conspicuous bedding 



plane at the base * 3 5 5 



3. Massive gray layer near bottom of quarry, 



which has pretty compact structure, but is not 



so hard as the three layers which immediately 



