608 GEOLOGY OF OHIO. 
LIMESTONE. 
By Dr. Gro. W. Hawes. 
CINCINNATI GROUP.—The southwestern corner of Ohio is covered 
by what is called the Cincinnati group of limestones, a geological for- 
mation equivalent to the Hudson River beds of New York. These 
rocks were very early quarried and used for construction purposes, 
although the special quarries that are at present in operation have been 
much more recently developed. Quarries once located on the out- 
skirts of Cincinnati have suspended operations on account of the 
growth of the city. The material is mentioned in the early reports 
upon the geology of Ohio as having been used in 1838 for building, 
burning into lime, macadamizing roads, and even for ornamental pur- 
poses. (a) 
Professor Orton gives the following as the order in which the beds 
which constitute the Cincinnati group in southwestern Ohio are ar- 
ranged : 
The Point Pleasant beds, 50 feet thick, constitute the lowest of the 
series. The Cincinnati beds proper overlie these, and are 425 feet 
thick. The Lebanon beds are the highest, and are 300 feet thick. 
Quarries are developed in each of these horizons. The rocks where- 
ever they are quarried are very much alike, and are called in commerce 
blue limestones. As a rule they are filled with fossils, and occur in 
layers that are from half an inch to 12 inches in thickness, which are 
interstratified with beds of shale or clay. Protessor Orton says that 
while this blue limestone has been used from the first settlement of the 
country, it has hitherto enjoyed the reputation of being serviceable rather 
than beautiful; but within the last few years it has been so treated 
by combination with other building stones as to produce very fine 
architectural effects, as can be seen in the recent buildings of the city 
and suburbs of Cincinnati. (6) 
The quarries in the Cincinnati group of limestones are located 
nedr Cincinnati, more on account of the local demand for the most ac- 
cessible stone than for the superior quality of the material at this point. 
There are limestones in the river bed which are upon the same level as 
the quarries which produce excellent stone at Covington, upon the 
(a) Professor Locke in Second Annual Report on Geological Survey of Ohio, by W. W. Mather, 1838. 
(0) Report of the Geological Survey of Ohio, Vol. I, Part i, p. 378. 
