THE NIAGARAN FORMATIONS OF WESTERN OHIO 343 



Thickness Thickness 



No. Feet Inches Feet Inches 



6. Dayton limestone. — Massive zone at top of Day- 

 ton limestone with a thickness of 2 feet 3 inches, 



which splits into 5 layers and the first three in 



descending order are from 4 to 5 inches each in 



thickness, while the fourth from the top is 8 



inches and the fifth 4 inches thick. Light-gray 



with blotches and spots of dark-gray, compact 



rock with stylolites or hackletooth structure at 



the bedding planes 2 3 7 11 



5. Layer of shaly, greenish limestone 10 5 8 



4. Compact layer of light-gray color with some 



dark-gray blotches containing iron pyrite and 



calcite 1 o 4 10 



3. Shale to shaly limestone parting 2 3 10 



2. Dark- to light-gray limestone which splits into 



several layers 3 2 3 8 



1. To water level in old quarry pit 6 6 



In the foregoing section, Nos. 7 and 8 correspond to the shale 

 zone (No. 7) of the Ehlers quarry and form the upper member of 

 the Osgood beds. The Laurel limestone comprises Nos. 9 to 16, 

 inclusive, with a total thickness of 7 feet 2 inches. The extreme 

 upper part of this quarry wall shows nearly 3 feet of light-gray 

 fossiliferous rock which is referred to the Springfield dolomite. 



Professor Bownocker has recently published a bulletin on the 

 "Building Stones of Ohio" which contains a section of this quarry. 1 

 In this bulletin the zone called the "West Union limestone'' corre- 

 sponds to the "Mottled zone," No. 17 of the foregoing section, and 

 the upper limestone of the "Osgood beds" is what the writer is 

 correlating with the Laurel limestone of Indiana, and includes Nos. 9 

 to 16, inclusive, of the foregoing section. The blue shales overlying 

 the Dayton limestone of Professor Bownocker's section correspond 

 to Nos. 7 and 8 of the writer's section, the top of which he regards 

 as corresponding to the top of the Osgood beds of Indiana. 



GENERAL SECTION ALONG LUDLOW CREEK 



A general section of the formations exposed at Ludlow Falls and 

 in the series of quarries on the northern bank of the stream has been 



1 Geological Survey of Ohio, 4th Ser., Bull. 18 (1915), P- 37- 



