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 tban 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 

 Palseoniscus, 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 is 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 well exposed on 

 the lake shore at Avon Point, and less perfectly in the bed and banks of 

 French 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 



