362 
GEOLOGY OF THE FIRST DISTRICT. 
the Geological Survey, has since cupelled some of the ore, and obtained silver.* Whether it 
exists in such quantity as to. make its separation a matter of importance, is not ascertained. 
Pyritous grit. 
In some places, the upper strata of the Shawangunk grit are more or less loaded 'with 
pyrites. Occasionally this mineral forms a large portion of the rock, constituting the gangue, 
in which the pebbles and finer grains of siliceous matter are imbedded. Boulders of this 
variety of the grit rock were observed scattered over the country in the counties of Orange 
and Ulster, southeast of the Shawangunk mountains; and boulders of precisely similar 
appearance and composition were seen on Long island near Sand’s point, and in other places. 
A locality of this pyritous grit was examined sOuth of Rochester, Ulster county, where 
the rock contained pyrites, and had been reputed to be a silver mine. A small excavation 
had been made. The only use to which it could be applied would be the manufacture of 
copperas, but it is not sufficiently abundant there to warrant any expenditure. This locality 
is near the base of the Shawangunk mountain, and one fourth of a mile south of the Mule 
kill, in the township of Rochester. 
3. Rocks similar in character to the Shawangunk grit, and the interstratified and overlying 
red rocks. 
These were observed in Orange county, and they extend from the New-Jersey line on the 
west side of Long pond, north-northeast to near Canterbury in Cornwall. They have not 
been traced continuously between the points indicated, but at intervals. This is the same 
formation as that described by Prof. H. D. Rodgers under the name of the Middle Secondary 
rocks of the Green-pond and Long-pond mountains.! Rocks of similar character are found 
on the east side of the Hudson valley, ranging from Fishkill near Matteawan, through Dutch¬ 
ess, Columbia, Rensselaer and Washington counties, into Vermont in West-Poultney, a dis¬ 
tance of two hundred miles from their southern termination in New-Jersey. Prof. Rodgers 
is doubtful about the geological age of this formation, but he inclines to the opinion that it is 
equivalent to the sandstones of the Middle Secondary (New Red-sandstone), which are asso¬ 
ciated with trappean rocks in New-Jersey andNew-York. The observations on the geological 
survey of the First district of New-York do not quite demonstrate the age of this rock; but 
if the red slates and grits on the east side of the Hudson, which are the same as those of 
Pine hill in Cornwall, Orange county, are the same as those of Bellvale mountain near Long 
pond, and the Green-pond mountain, which they strongly resemble, and of which they appear 
to be an extension, they are older than the Middle Secondary sandstone (New Red-sandstone) 
of New-Jersey, to which Prof. Rodgers inclines to refer them, and are probably the geologi- 
* Vide Assembly Document No. 275, for 1839, p. 51. 
t Final Geological Report of New-Jersey, pp. 171,175. 
