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_ Geological Survey of the State of New York. 79 
#.* a 
“The lower Ludlow rock has its equivalent in a grit above the 
Oriskany sandstone.” — f 
The full account of this extended series will prove of great value 
aed iiveetipating@il formations of our northwestern States. In 
ever, the reports of their surveys present but little that is avail- 
able to a scientific classification. “The lithological character of 
the rocks may be obvious, and easily interpreted ; but it is clearly 
impossible to deeide upon their geological relations or equivalent 
character, especially when comparing formations of distant coun- 
tries, without a particular knowledge of their organic remains. 
The conditions that govern the development and existence of or- 
ganic beings, are so complicated, and, if we may so say, of an order 
so much higher, that their coincidence in different localities is far 
more remarkable than that of those producing similar rocks ; and 
of course the evidence based upon the resemblance or dissimi- 
larity of the fossils, should be more weighty than that derived 
from these qualities of a rock. . 
Mr. Mather’s survey of the first district, has developed “ the 
Catskill mountain series, consisting of coarse andfine grits, gray- 
ish, greenish, and various shades of red and brown, which lie 
thick bedded with water lines of deposition, strongly marked 
. ‘where a cross fracture exhibits the structure ; conglomerates, of 
various degrees of coarseness, grayish, greenish, and red; slaty 
sandstones, with slates and shales of various colors, red, green, 
spotted, gray and black.. ‘Testacea are the principal fossils of 
the lower, and plants of the upper portion of the series, with 
Seams and layers of pure anthracite ;” and probably all of them 
are below the old red sandstone ; and they have below them the 
lelderberg limestone group, No. 7, of Mr. Conrad’s synopsis, in 
his second report, which “embraces a series of limestones, with 
subordinate beds of shales, slates, and silicious grits. It skirts 
a € group of rocks last described, in a parallel zone, and under- 
lies them, it is supposed, through their whole extent.” 
“The Shawangunk grit, next below, varies from a conglome- 
tate to a fine grained grit rock; it isalmost entirely silicious, and 
Senerally white or light gray in color, with one bed at the r 
part that is red. . The mountain on which this rock abounds, has 
taken its name from the predominant color of the rock—the wo; 
Shawangunk ( Shongum) meaning, it is said, in the language of 
the aborigines of the country, white rocks. 'This rock, which is 
largely developed in Pennsylvania and New Jersey, is much less 
