Stevenson : V2 
: Chemung and Catskill, 
grit. He has shown also how intimately related the Bedford | 
shale is to the underlying Cleveland-Erie shale, and that forms of 
Lower Carboniferous type made their appearance only toward the 
close of the former, so that there the faunas overlap as in north- 
western Pennsylvania. It is possible that when the detailed re- 
vision of the Devonian column has been carried across from 
eastern New York by Prof. H. 8. Williams into Ohio, the beds 
of the Catskill will be found interlocking with beds of other 
tints, which in Ohio become the Bedford and Cleveland shales. 
If we bear in mind these facts: 
First, that the Chemung and Catskill deposits were laid down 
in a shallow basin subsiding most rapidly at the east and along a 
line rudely parallel to the Blue ridge trend. 
Secondly, that the deposits would be much greater near the 
main land at the east than at 200 miles away; so that 600 feet 
more or less of fine material in Ohio would more than fairly 
represent the 4,000 feet, more or less, of Chemung in eastern 
Pennsylvania. And 
Thirdly, that the water beyond the reach of the great land 
wash held a Chemung fauna throughout the whole time of Cats- 
kill deposit-—there will be no serious difficulty in the way of ac- 
cepting this suggestion, 
The conclusions to which I am led are 
First. That the series from the beginning of the Portage to 
the end of the Catskill, forms but one period, the Chemung, 
which should be divided into three epochs, the Portage, the 
Chemung and the Catskill. 
Secondly. That the deposits of the Catskill epoch were not 
made in a closed sea or in freshwater lakes. 
Thirdly. That the disappearance of animal life over so great 
part of the area toward the close of the period, was due to gradual 
extension of conditions existing in southeastern New York as 
early, perhaps,,as the Hamilton period. 
Fourthly. That the Chemung period should be retained in the 
Devonian. 
