THE DELAWARE LIMESTONE 431 



Thickness Total Thick- 



No. (Feet) ness (Feet) 



8. Delaware limestone. — Upper portion thinner-bedded 9 \ 55 J 



than the lower part of this zone, impure dark colored 



limestone containing considerable chert. Lower part 



is fairly massive, impure bluish-gray limestone 



weathering to a brownish color and containing nodules 



of chert. This zone is shown on the southern bank 



of the stream at the upper end of the gorge, where the 



measurement was made. This zone is not especially 



fossiliferous, and at the base is a shaly parting. 

 7. Layers of brownish limestone, alternating with thick 4 J 46 



layers of chert, all of which are undulating, giving a 



contorted appearance to the entire zone. 

 6. Brownish, fairly thick-bedded limestone, with chert 6J— 4i| — 



partings, in which is a small abandoned quarry on the 



northern bank of the run. Thickness, about 6 feet 



5 inches. 

 5. Heavy layer of quarry stone at base of quarry. ij 35 



4. .Shaly to thin-bedded brownish limestone, with layers 8f 33J 



of chert. 

 3. Brownish, massive bituminous limestone, which is 4§ 24! 



fossiliferous. Base of the Delaware limestone, but 



there is no shale zone as in the sections farther south. 



This gives a thickness of nearly 35 \ feet for the Dela- 

 ware limestone in this glen, which is about 5 feet more 



than in the Franklin County sections. 

 2. Columbus limestone. — Light gray, massive, fossilifer- i8| 20 



ous limestone. The bone-bed is fairly well defined 



here at the top of this formation, but the change of 



color from the brownish Delaware to the light gray 



Columbus is conspicuous. The smooth layer was 



noted by Mr. G. F. Lamb at a distance of 10 feet below 



the top of the Columbus. 

 1. Covered interval to level of Olentangy River. \\ \\ 



Mr. G. F. Lamb recently measured this section and made it 

 twenty-one and one-half feet from the river level to the top of the 

 Columbus limestone. The rocks forming the Delaware limestone 

 in this section are quite sharply folded, so that some care is 

 required in obtaining an accurate measurement of their thickness, 

 while at the lower end of the Delaware part of the gorge is a faulted 

 block on the southern side. Zone No. 4 of the above section, showing 

 the alternation of shaly to thin-bedded limestone with layers of chert, 



