ORISKANY SANDSTONE. 
123 
16 . ORISKANY SANDSTONE. 
White Sandstone of the Report of 1838. 
(No. 7 of the Pennsylvania Survey.) 
28 . 
No. 1. Arenaceous delthyris (D. arenaria). No. 2. Elongated atrypa (A. elongata). 
No. 3. Peculiar atrypa (A. peculiarisj. 
This sandstone holds a fixed position in the series, and is readily traced from east to west 
through the district, by its composition and its numerous characteristic fossils, not so much as 
to kinds as individual species. Its position is best seen in the first district near Salem ; the 
Helderberg division, of which it forms a part, being complete. It projects from the side of 
the Helderberg mountain, forming a terrace resting upon the Catskill shaly limestone, in the 
upper part of which the encrinal pelvis is found; the sandstone passing under, or covered 
with the cauda-galli grit, the latter being a thick abrupt mass. 
In the third district, its immediate associates cease entirely before reaching the west end of 
Madison county ; and the sandstone from thence rests upon the Manlius water-lime group, 
and is covered by the Onondaga limestone, the three rocks being coassociates to Cayuga lake. 
It is very variable in thickness, owing probably to the unevenness of the surface upon which 
it was deposited. 
With some exceptions, this sandstone consists of a medium sized quartz sand, such as is 
derived from primary rocks, either of granite, gneiss or mica schist. It is of a light yellow 
color when pure, as at Oriskany falls. At other localities the yellow color is often shaded 
brown, or of some other dark color. This sandstone and the calciferous sandrock, including 
