ALLUVIAL DIVISION. 113 
back from the river, and may be subterranean streams, as they have been defined, but no 
examination was made. 
In Ulster county, a sinking spring, called the 0-pack-oke spring, (an Indian name,) is on 
the top of Shawangunk mountain, opposite Napanock. I did not see it. It is probably in 
the Shawangunk grit, and sinks in its fissures. 
In Rochester, Ulster county, the stream which flows from the mountains on the northwest, 
and crosses the road from High falls to Rochester, about four or five miles from the former 
place, sinks into the crevices of the limestone on the right of the road,- and reappears in the low 
grounds between the road and Rondout river; but when the stream is high, it flows across 
the road, and during the freshet of the winter of 1838, washed away the bridge. 
In Orange county, in New-Windsor, the water from the outlet of Little pond sinks into a 
cavern in the limestone. At the distance of three quarters of a mile, a stream, supposed to be 
the same, emerges from the ground. “ At times the stream can be heard beneath the ground, 
thirty or forty rods before it bursts out at the surface,”* 
A natural bridge spans the stream that flows into the southwest end of Popelo’s pond in 
Monroe, Orange county. The rock is the white crystalline limestone, resting on hornblende 
rock on one side, and on granite, it is supposed, on the other, though the rock is concealed by 
the soil. It is used as a bridge, and “ one might cross it without being aware, unless the 
noise of the brook aroused his attention. The breadth of this bridge across the stream is fifty 
feet, and its length up and down the stream seventy-five or eighty feet.”t The water, at the 
time of Dr. Horton’s visit, filled the cavity, so that he could not see through it; but in times 
of drought, people pass through it. 
7. Sulphur and Carburetted Hydrogen. 
Native sulphur has been found in few places in the First Geological District; and in all the 
localities that have been observed in the survey, its presence in an uncombined state is the 
result of alluvial causes. 
Sulphur is deposited from some of the sulphur springs at Sharon, Schoharie county. At 
some springs it is white, and perhaps a hydrate ; at others it is yellow or grey, and sometimes 
dark colored. The quantity deposited is not very great, but the earthy‘matter around some 
of them contains a large proportion of sulphur, and the sticks, moss, grass, etc. are encrusted 
with it. 
In Phillipstown, along the shore of the Hudson, south of and near the point of Gouver- 
neur’s cove, about east of Gee’s point, where pyrites have decomposed, a grey or bluish grey 
powder, composed almost entirely of sulphur, is found. Another locality is about one mile 
east of the above, near the locality of laumonite and stilbite : it is, in cavities in quartz, where 
* Dr. W. Horton’s Report; 3d Annual Geological Report, N. Y. p. 158. + Ibid. p. 140. 
Geol. 1st Dist. 
15 
