The Geology of Cincinnati. 61 
quarried. From 4o to 50 feet are shown in the quarries, 
leaving some 30 feet more before reaching the top of the 
Trenton. 
An average section of the exposure in West Covington is 
as follows: 
None Crinoidal layer, 00) 6 (sig ag Absa. a ul = ite: 
No. 2. Limestone layers with some shale,. .. . 27 feet. 
No. 1. Layers consisting mainly of bluish shale, 17 feet. 
Concealed to low-water mark,...... 4 feet. 
AG Gall se ee Oe ee eee its 8 we SO Tete 
No. 3. This layer marks the top of the Trenton formation 
about Cincinnati. Utica shale rests upon its upper surface 
with more or less unconformity by erosion. It is composed 
of comminuted fragments, mainly of separated joints of 
crinoid stems, indiscriminately thrown together and more or 
less firmly cemented, the arrangement giving evidence of 
current formation and perturbed changing conditions. The 
fact that the limestones beneath this layer give place to the 
shale above it indicates that a very great change had come in 
geographical conditions. This layer, No. 3, contains several 
forms restricted to it, most noticeable being the huge 
Escharopora ponderosa (Ulrich), and the Dendrocrinus dyert 
Meek. 
No. 2. This division consists mainly of even-bedded, close- 
textured, dove-colored limestones, varying from two to six 
inches or somewhat more in thickness. Some of the layers 
are semi-crystalline, some so close-textured that all traces 
of fossils have disappeared, some are a mass of fossils. This 
last is especially true of the ‘‘gastropod layers,” in the lower 
part of this division. On the whole fossils are abundant, but 
good specimens are not to be easily had. The shale partings 
between the limestone layers, varying from one to eight 
inches in thickness are usually barren, but are sometimes 
very rich in fossils, especially minute ostracoda. 
No. 1. These shales are usually bluish and friable, and 
commonly entirely destitute of fossils. This shale is a 
variable feature; in some places it is much reduced in thick- 
ness, then the limestone division is increased in thickness. 
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