THE DELAWARE LIMESTONE 435 



Thickness Total Thick- 

 No. (Feet) ness (Feet) 



4. Layer of brownish, calcareous shale, weathering to \ io| 



an ash color, in which part of a fish tooth was found. 

 Lithologically very similar to the shale at the base of 

 the Delaware limestone. in Franklin County. 



3. In upper part of layer, fragments of teeth and fish 2tV 10 \ 



bones similar to bone-bed at top of Columbus lime- 

 stone in central Ohio. Lower it is more crystalline in 

 structure, grayish in color, and contains cup corals 

 and other fossils. This contact is shown in Fig. 3, 

 where the collecting bag rests on top of this zone, and 

 the hammer indicates the superjacent shale of No. 4. 



2. At this horizon generally a conspicuous zone of Erido- h 8| 



phyttum vemeuilanum E. & H. from 4 to 6 inches in 

 thickness. 



1. Exposure at angle of southern wall, which extends 7§ 7§ 



about as low as in any part of the quarry. This lime- 

 stone is rather bluish-gray, weathering to a lighter 

 color, somewhat crystalline and fossiliferous. At the 

 angle all of the rock belongs in the Columbus lime- 

 stone, but there is quite a heavy dip to the west, so 

 that farther along the wall the Delaware limestone is 

 shown as described in the upper part of this section. 



The brownish limestone alternating with layers of chert, which 

 form the upper part of this section, closely agrees in lithologic char- 

 acters with the second zone of the Delaware limestone, which succeeds 

 the brownish shales or limestones in the sections in the northern 

 part of Franklin and southern part of Delaware Counties. In the 

 upper part of No. 3 of the above section are a considerable number 

 of fragments of teeth and bones of fish, forming something of a bone- 

 bed, which is overlain by a three-inch layer of brownish shale. Two 

 feet one inch below the top of the bone-bed is a conspicuous Erido- 

 phyllum zone, similar to the one occurring in the exposures of the 

 Columbus limestone, near Columbus, from two feet eight inches to 

 three feet below its top. It therefore appears to the writer better 

 to draw the line of division between the Columbus and Delaware 

 limestones in this section at the top of No. 3, and refer the five feet 

 ten inches of rock between it and the base of the lowest chert zone, 

 or No. 7, to the Delaware limestone. This will agree lithologically 

 with the sections in the southern part of Delaware and northern part 



