THE GEOLOGICAL AGE OF THE COAL OF WYOMING. 
BY EDWARD D. COPE, A.M.* 
Is his Geological Survey of Wyoming, Professor F. V. Hayden 
thus describes the great coal area of Wyoming. “About two 
miles west of Rawling’s, springs begin to appear again, and at 
Separation Platanus Haydenii, Cornus acuminata and other unde- 
termined species of plants occur. This point forms the eastern 
: rim of a basin which extends about one hundred and ten miles to 
the westward. A new group comes in which I have named the 
Washakie group, from the fact that near this station are beds of 
calcareous sandstone and limestone, composed of an aggregate of 
fresh water shells. As they are mostly casts it is difficult to 
identify the species, but Mr. Meek has named the most abundant 
kind, Unio Vasakei. Soon after leaving Bitter Creek, coal strata 
of Eocene age rise to the surface from beneath the surface of the 
Miocene beds of the Washakie group, with a reversed dip, Here 
we find numerous beds of coal, and in the rocks above and below 
the coal, are great numbers of impressions of leaves, and in the 
clay, oyster shells of several species. At Black Buttes Station 
eight hundred and fifty miles west of Omaha, we find Sabal Camp- 
bellii, Rhamnus elegans, etc. At Point of Rocks farther west, Plat- 
nus Haydenii, Cornus acuminata, etc., occur. At Hallville the 
black slaty clays forming the roof of one of the most valuable of the 
coal beds of this region, are crowded with bivalve shells, two spe- 
cies of which Mr. Meek has named Cyrena fracta and C. crassatelli- 
Sormis, regarding them as Tertiary. They are undoubtedly brack- 
ish water forms, and show a sort of middle position, that is middle 
or upper Eocene. That there is a connection between all the coal 
eds of the west I am prepared to believe, yet until much clearer 
light is thrown upon their origin than any we have yet secured, I 
‘Shall regard them as belonging to any transition series or beds of 
Passage between the true Cretaceous and the Tertiary. It will be 
Seen at once that one of the most important problems in the geol- 
8y of the West awaits solution, in detecting without a doubt the 
ancement of 
* Read at the Dubuque Meeting of the American Association for the Adv 
‘ . Aug., 1 
ug., 1872, (669) 
Science. 
