femRNAL OF GEOLOGY 
FEBRUARY-MARCH 1907 
Ete DEVONIAN SECTION OF ITHACA, N.Y... PART Ti 
THE DISCRIMINATION OF THE NUNDA-CHEMUNG 
BOUNDARY 
HENRY SHALER WILLIAMS 
ithacas Ne Ye 
[Concluded from page 598] 
THE CHEMUNG GROUP OF HALL 
The name Chemung group was originally proposed by James Hall 
in the Third Annual Report of the New York State Geological Sur- 
vey (p. 324), published as “Assembly Document No. 275” in 1830. 
The formation was described and lithologically distinguished from 
the rocks of the immediately underlying formation by the following 
characteristics: 
The tops of the hills and high grounds in the towns of Erie, Veteran, and 
Catlin, display a group of rocks and fossils very distinct from those last described. 
The essential difference is the lithological characters of the sandstone of this 
group in the absence of argillaceous matter in most of the layers, these being 
merely a pure siliceous rock, harsh to the touch, and generally of a porous texture; 
while still a large proportion of the mass consists of compact shales and argil- 
laceous sandstones of a softer texture than those below. The surface of the sand- 
stones is rough, while those below are smooth and glossy, and being never rippled, 
prove that the rocks were deposited in a quiet sea. (P. 322.) 
This definition gives a fair idea of the most conspicuous differ- 
ences separating the higher from the lower rocks of these sections, 
t Published by permission of the Director of the United States Geological Survey. 
Concluded from p. 598 of Vol. XIV, No. 7 (1906). 
Vol. XV, No. 2 93 
