LORAIN COUNTY. 213 
these limestone bands I also found a triangular fragment, six inches 
long by four inches wide and one and a half inches thick, of the bone of 
some gigantic fish, probably allied to Dinichthys. This is the only trace 
of this fish yet found, and it indicates that the Bedford shale may upon 
proper search furnish some much more interesting material than any 
yet obtained from it. At Berea a considerable number of fish teeth have 
been obtained from the calcareous bands in the Bedford shale, so that 
though at first thought utterly barren, it may prove quite rich in new 
species of fossils. 
Cleveland Shale-—This is a black bituminous shale, fifty or sixty feet 
in thickness, which is well exposed beneath the Bedford shale in the 
valleys of Black and Vermilion rivers. It contains over ten per cent. of 
carbonaceous matter, and this gives it a black color, by which it may be 
at once recognized when freshly broken. Where long exposed, its carbon 
is burned out by oxidation, and it becomes gray. Hence its outcrops, 
taking the color of the other gray shales in the series, may not be iden- 
tified without some excavation. The only fossils found in the Cleveland 
shale of Lorain county up to the present time are minute, rhomboidal, 
enameled fish-scales. These belong to a ganoid fish, probably a species of 
Palzoniscus, but no entire individuals have yet been obtained. The 
Cleveland shale has no economic importance, except that it is clearly 
the source of the petroleum found at Grafton and Liverpool. 
Erie Shale.—This is the summit of the Devonian system, as now classi- 
fied. It is a mass of gray, argillaceous shale, with thin flags of sand- 
stone and lenticular iron ore. It is not easy to say with accuracy what 
its thickness 1s in Lorain county, but it is somewhere from 100 to 150 
feet in the central and eastern portions, while in the valley of the Ver- 
milion it has almost disappeared. In this county it is the wedge-shaped 
edge of a formation that thickens rapidly eastward, forms the lake shore 
most of the way from the mouth of Black River to the State line, and at- 
tains a thickness of fully 2,000 feet in the State of New York. In most 
places it is very barren of fossils, and has yielded none in Lorain county; 
nor does it furnish any material which can be made to contribute to the 
wealth or comfort of the inhabitants. The Erie shale is weil exposed on 
the lake shore at Avon Point, and less perfectly in the bed and banks of 
Wrench Creek and Black River near their mouths. 
The Huron Shale.—This is a formation which attains a thickness of 
300 feet or more, and is exposed in a continuous belt reaching from the 
Lake through the central part of the State to the Ohio. In Huron county it 
forms the banks of Huron River, and its entire thickness is exposed. In 
Lorain county it is only seen on the lake shore between Avon Point and 
