CHEMUNG GROUP, 
251 
in. 
Chemung Narroivs. From a sketch by Mrs. Hall. 
28. CHEMUNG GROUP. 
Including the Ithaca and Chemung groups of the Annual Reports. 
(No. 9 or the Pennsylvania Survey.) 
[See section, Plate VII., and R of woodcut, page 27.] 
This group consists of a highly fossiliferous series of shales and thin-bedded sandstones, 
sometimes in well-defined and distinct courses, and an infinite variety resulting from the ad¬ 
mixture of the two ingredients. Except in a few localities, there is no very strongly marked 
line of division between this group and the one below. The distinction consists in the pre¬ 
sence of numerous fossils and the coarser grained sandstones, which are usually more impure 
from argillaceous admixture than those below. Its lithological characters, however, are va¬ 
riable ; and though well marked across a single line of section from north to south, still another 
at a short distance east or west of this presents considerable variation. 
These rocks, however, can everywhere be described as a series of thin-bedded sandstones 
or flagstones with intervening shales, and frequently beds of impure limestone resulting from 
the aggregation of organic remains. The whole series weathers to a brownish olive, and even 
the deeper green of the shales assumes this hue. 
The shales vary in color from a deep black to olive and green, with every grade and mixture 
of these. The sandstones are often brownish grey or olive, and sometimes light grey. More 
32* 
