428 CHARLES S. PROSSER 



Thickness Total Thick- 

 N a (Feet) ness (Feet) 



10. Brownish-gray thin-bedded limestone, alternating with 6|± 59I 



layers of chert, shown to best advantage on the south- 

 east bank, a little above the contorted layer in the bed 



of the stream. This zone is conspicuous in the glens 



farther north, in the southern part of Delaware County. 

 9. Rather heavy-bedded grayish to brownish limestone. 2\ 53 



8. Zone of contorted thin limestone and chert shown in 2% 5of 



the bed of the run and on its banks farther down the 



stream. This corresponds to the contorted stratum 



noted by Professor Winchell in sections of this lime- 

 stone in the southern part of Delaware County. 1 

 7. At the base of the limestone, directly on top of the ij+ 48 



shale zone, is a thicker layer of chert, followed by 



layers of brownish limestone 2\ inches or more in . 



thickness. The measurements for this zone vary from 



1 foot 6 inches to 2 feet. 

 6. Brown, bituminous shales weathering to a light gray or 6± 463 



ash color. The layers are even and thin, rather arena- 

 ceous in places, interrupted by several layers of chert, 



and contain a considerable number of fossils, especially 



in the lower part, although the number of species is 



small. The measurements of this zone vary from 5 



feet 10 inches to 6 feet 6 inches, and it is well exposed 



on the southeastern bank of the run, where it has the 



general appearance of a bank of shale. It is shown in 



Fig. 1, the top of the zone being indicated by the ham- 

 mer. This is the shale which Whitfield correlated with 



the Marcellus of New York, and it forms the base of 



the Delaware formation in this section, which has a 



thickness of 32J feet. 

 5. Columbus limestone. — In the upper part of the top 7I+ 4°i~ 



stratum are numerous fragments of the teeth, plates, 



and bones of fishes, the bone-bed which is well shown 



on the southeastern bank of the run a little above the 



fall. In the quarry wall, 5+ inches below its top, 



Spirifer acuminatus (Con.) Hall occurs, and 7 feet 3 



inches lower is the "smooth layer," which is found 



from 9 feet 2 inches to 10 feet 5 inches below the top 



of the Columbus limestone in all of the sections in the 



Columbus region. In the upper Casparis quarry 



there are apparently two such layers, the upper one 



9 feet 7 inches, and the lower one 10 feet 6 inches, 



below the top of the formation. 



1 Geological Survey of Ohio, Vol. II, Part I (1874), p. 289, No. 22. 



