FISHES OF THE CARBONIFEROUS SYSTEM. 129 
fossils—the equivalent of the Portage sandstone and the Chemung group 
(the Erie shale); the lower, which contains fossils of the Genesee and Port- 
age shale, by the loss of the argillaceous members has become in central 
Ohio a nearly homogeneous bituminous shale three hundred to four hun- 
hundred feet in thickness (the Huron shale). At the mouth of Rocky 
River, at Cleveland and eastward to Erie, the lake shore is composed of 
gray shale, with bands of flaggy, often micaceous, sandstone and lenticular 
concretions of iron ore. This was named the Erie shale, as throughout the 
interval mentioned it has a distinct entity, and is not the equivalent of any 
one stratum or formation in New York. At Painesville the Erie shale, by 
the boring made at General Casement’s house, was proved to have a thick- 
ness of seven hundred feet, and there to rest upon a black shale, from which 
it was sharply separated. From two hundred to three hundred feet of the 
upper portion of the Erie shale are here wanting, having been removed by 
erosion; but this portion may be seen by following up the valley of Chagrin 
River. Hence we have evidence that there the Erie shale is not far from 
one thousand feet in thickness and is essentially alike throughout; that is, 
is composed of soft dove-colored clay shale, with flags of sandstone. 
Above the Erie shale we find in that vicinity, at the base of Little 
Mountain, the edge of the Cleveland shale; which, having a thickness of fifty 
feet at Cleveland, thins towards the east and apparently runs out before 
reaching the Pennsylvania line. All the fossils yet obtained from it are 
identical with those found in the Waverly beds above. ‘Toward the west 
the Erie shale thins rapidly, and in Huron County is in one locality not 
more than ten feet in thickness. So far as known none of the fossils of the 
Huron occur in the Erie or Cleveland shales.. Hence, to unite these three 
distinct formations is, in my judgment, to misrepresent the geologic record. 
Prof. L. E. Hicks announces?’ the discovery of the Cleveland shale in 
Delaware County, Ohio, but I think he has found there the Berea shale, 
which lies immediately above the Berea grit. This latter shale is persistent 
southward, and is apparently the black shale, so rich in fish remains at 
Vanceburgh, Kentucky. I suspect the Cleveland shale does not pass south 
of the line of the Western Reserve. 
'Am. Jour, Sci., 3d series, vol. 16, 1878, p. 70. 
MON XVI 9 
