646 GEOLOGY OF OHIO. 
The Niagara rock is ill-adapted to building purposes, coming out of the 
quarry in massive and ungainly blocks; but the close proximity, in this 
region, of the fine courses of the Waverly quarries renders it unnecessary 
to turn it to such uses. 
2. The Huron shales are, perhaps, the most characteristic formation 
of the western half of Ross county. They occupy a large area, and im- 
press peculiar features upon the soil, the vegetation, and the scenery. 
They afford at Benner’s Hill, above mentioned, the heaviest section 
yielded by the formation in Ohio, viz., three hundred and thirty-two feet. 
The composition of the series, as shown in this and closely adjoining 
sections, has two points that deserve mention. The first is the occur- 
rence of twenty-six feet of white and blue clays at the base of the series ; 
and the second, which is much the more interesting observation, is the 
occurrence of a calcareous layer, well charged with fossils, at the height 
of forty to fifty feet above the base of the system. The clays are shown 
on the west side of Benner’s Hill. The limestone seam is best seen at 
Ferneau’s Mill, one mile east of Bainbridge. Mr. J. H. Poe, of Chilli- 
cothe, first called attention to its existence, and to him the Survey is in- 
debted for a very interesting fossil—the body of an hitherto undescribed 
crinoid—obtained from this locality. The calcareous seam varies be- | 
tween three inches and six inches in thickness. Its composition is 
shown in the appended analysis, made by Prof. Wormley: 
SUL CTGNA CTOs Meare doeee Re OR De TSU AID ATTN SUL SD ha SNR nN 53.20 
Pron jan abun Bea i a scenes lea Ne eee leche a Set ticle en ite Ane ca td RUNS 2.10 
Carbonate Of slime cesece coe t eee ike h ec tle eee ae ee ote caer See NUD AL Reeds aR MRE 37.20 
Carbonate Of ‘Maonesta sei. cusiik cccese eons cues osaeciccsc ct esteateieaactaneeteaninetee 6.88 
99.38 
Its interest lies in the fact that no other such seam has been reported 
in the whole extent of this formation. Taken as a whole, the Huron 
shales are almost entirely destitute of traces of either vegetable or animal 
life. Two brachiopod shells, a Discona and a Iingula, have been found at 
various points in the system, and the great concretions which the forma- 
tion holds have yielded the remains of some remarkable species of fishes ; 
but throughout most of its extent it is utterly barren of paleontological 
interest. One of the difficulties in settling the Ohio geological scale, or, 
at least, of correlating certain of its upper members with the members of 
the eastern geological series, has lain in the fact that fossils, the true 
labels of the rocks, are here wanting. The outcrop of the slates on the 
western side of Ross county promises valuable contributions to our 
knowledge of the life of the seas and shores during the long period in 
which these black shales were accumulating upon the floor of the an- 
