598 
GEOLOGY OF THE FIRST DISTRICT. 
This-quarry is about two hundred to three hundred feet north and south, and eighty feet-east 
and west and fifty feet in depth, and still considerably above tide-water at its base. 
Northward on the cliffs the rock is from^ twenty to sixty feet above tide-water, and generally 
covered with thin soil except in the valleys. The strike, in a great number of observations, 
varied from N to N 40° E, and the dip from 45° to 75° W. 
On the old road to the public house called “ Cato’s,” forty rods southwest of the house, 
and on the southerly side of the track (it lies between 49th and 50th-streets, and about ten 
rods southeast of 3d avenue, vide page 595), there are abundant drift furrows. The rock 
crosses the track and appears on both sides, but the furrows are most distinct on the southeast 
side, covering a surface forty-two feet wide and two hundred feet long. Direction N 25° W. 
Same grooves and same direction west of avenue. 
48th-street to 50th-street: Isaac Lawrence’s summer seat. Here the rock projects into the 
river with cliff thirty-five feet high. Strike N 30° E. Dip vertical. Plenty of greenstone 
boulders in the valleys ; gneiss of ordinary quality. 
The rock from the vicinity of the shot tower, 52d-street to 79th-street, still on the banks 
of the river, is gneiss of an inferior quality. Strike N 40° to 45° E, and the dip 80° to 85° 
E, and from that to 80° or 85° W. Boulders of coarse greenstone, sandstone and granite. 
79th-street: The rock on the banks projects in view. Strike N 40 to 45° E. Dip E 85 
to 90°. Inferior gneiss, charged with pyrites or oxide of iron from the decomposition of the 
pyrites. 
From 79th-street, or Blackwell’s island ferry, to the 3d avenue, the whole rock is covered 
with drift, the rock only appearing here and there. Strike N 45 to 40° E. Dip mostly 
vertical, with drift grooves, averaging N 45° W, 
79th to 82d-street, on the banks, strike on an average N 40° E. Dip 85 to 88°. Drift 
grooves abundant. Direction N 45° W. Boulders of greenstone in great abundance. Nine- 
tenths of the whole of these strata are perfectly straight for six hundred or eight hundred feet 
together. 
82d to 86th-street: On the banks, rocks more generally covered with drift loam and gravel, 
except on the water’s edge, but where visible observation gave for the strike N 40° E, and 
dip W 75 to 85°. The rock is only valuable for filling in. 
86th-street: Hellgate ferry is situated at the foot of 86th-street, and is on the same street 
as the stopping place of the railroad cars at Yorkville. The rock does not appear above 
ground from Yorkville eastward, until within a few rods of the river, when it appears of a 
loose texture, columnar structure, abounding in iron pyrites so much, that in decomposition 
from exposure, copperas enough is produced to injure or destroy in many places the growth of 
vegetation ; and in a dry time the copperas covers the ground, appearing like hoar-frost. Such 
was the condition of the rock when I first saw it on the 6th of September, 1838. The strike 
of the strata here is N 40° E, and the dip, though obscure, was 75 to 80°, and sometimes 
85° E. 
From this point, that is, from 86th-street to 94th-street, where we meet the marshes bor- 
