246 
[Assembly 
It is thought probable that localities may be discovered in the pyri- 
tous stratum, where copperas, and perhaps alum, may be manufactured 
with advantage. 
IL SHAWANGUNK GRIT. 
This rock varies in texture, from a conglomerate to a fine grained 
grit rock, and it is almost entirely silicious. It is generally white or 
light gray in colour, but there is one bed at the upper part of its mass, 
that is red. 
The mountain on which the grit rock abounds has taken its name 
from the predominant colour of the rock, — the word Shawangunk 
meaning, it is said, in the language of the aborigines of the country, 
white rocks. 
The Shawangunk grit has not a very extensive range in the 1st geo- 
logical district of New- York, but in New- Jersey and Pennsylvania, it 
is reported by Prof. Rodgers to be more largely developed. It extends 
in an almost unbroken range, from the New- Jersey line, on the top of 
the Shawangunk mountains, to Rosendale, near Kingston, a distance 
of 43 miles, where it disappears beneath the water limestone and the 
tertiary deposits of the Hudson valley. On the higher parts of the 
Shawangunk mountains, it generally lies in nearly horizontal strata, 
often thick bedded, and presenting mural escarpments of broken ends 
of the strata, 30 to 200 feet high. Some places on the eastern face of 
the mountain, present the strata with a high dip to the east-southeast ; 
but on the western face, the dip is almost uniformly to the west-north- 
west and northwest, at variable angles. That part of the range about 
Wurtsboro', Ellenville and Wawarsing, shows a dip from 30° to 60° to 
the west and northwest ; but with some local exceptions, the dip of the 
grit rock towards either extremity of the range is less, and does not 
generally exceed 8° to 15°. 
The thickness of the Shawangunk grits is variable, but its maximum 
is believed to be less than 500 feet, and its usual thickness is from 60 
to 150 feet. 
The strata are traversed by two great systems of fracture, one lon- 
gitudinal, and approaching more or less to the direction ,of the strike, 
the other transverse. Their usual directions are south 20° west, and 
north 20° east, for the first, and south 60° east, and north 60° west, 
'for the second. 
