The Geology of Cincinnati. 67 
of the two together is fairly constant. The color is not a 
matter of much importance. That the shales in southwestern 
Ohio are bluish or greenish in color, instead of black, does 
not preclude them from being of Utica age. 
The series of shales at Cincinnati overlying the limestone 
strata now referred to the Point Pleasant beds, was denom- 
inated the middle or Eden shales by Prof. Orton.* As there 
can be no doubt of their Utica age, Prof. Orton’s name 
lapses. Besides holding the same horizon in the geological 
scale as the New York Utica, the specific identity of several 
fossils, notably Zyriarthrus becki, very characteristic of the 
eastern Utica, has been established. Much more could not 
be asked. Besides being several hundred miles apart, the 
New York Utica was laid down under very different condi- 
tions and comparatively close to the source of its sediments, 
while the Ohio Utica was formed probably far from land in a 
large, rather shallow, interior sea. Under the circumstances 
the latter would have a very much more extensive and 
different fauna, especially if a barrier of some sort separated 
the two areas: 
The Utica at Cincinnati consists mainly of soft bluish or 
grayish shales, of which some harden on exposure and others 
decompose. Some layers form a close approach to marl. To 
only a very limited extent is it a surface formation, but is 
often exposed by ravines around the city and by cuttings in 
the lower slopes of the hills. At no point can a continuous 
section be studied, nor is it easy to correlate different ex- 
posures, as they present great similarity in lithological 
features and few or none of the common Utica fossils have a 
short vertical range. 
While the group consists mainly of shale, limestones are 
not altogether wanting, and occasionally a layer of limestone 
from four to six inches thick, or even more, will be found. 
The limestone forms, perhaps, one-tenth or one-eighth of the 
entire mass. Several of the limestones in the lower part are 
of the waved variety. Some of the shale layers abound in 
clay concretions. The thickness of the group at Cincinnati 
is about 260 feet. 
* Geol., Ohio, I, 1873, p. 372. 
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