No. 200.] 
173 
are adapted for the manufecture of glass. No localities were observed 
where extensive quarries for these purposes could be opened; but from 
the examinations made, there can scarcely be a doubt that they may be 
found. This rock is probably a continuation of that in Massachusetts 
and Vermont, described by Prof. Hitchcock, in his Geology of Massa- 
chusetts. 
Springs. 
The springs of Columbia and Dutchess counties contain earthy salts 
in solution in variable quantities. Some of the deposits of calcareous 
tufa and sinter, tufaceous marl, bog ore, and wadd, have already been 
mentioned. 
The shell marl of the swamps and ponds had a similar cause of depo- 
sition, but was first secreted by moluscous animals, to form their cover- 
ing shells. 
The water of the talcose rocks is much more pure than in the lime- 
stone, slate and clay districts, and it is probably as pure water as can be 
found, except rain water. 
It is expected that the analyst. Dr. Beck, will make known the com- 
position of the waters of the State. Copious limestone springs are fre- 
quently seen in those two counties, and some of them are of a size suffi- 
cient to turn a mill. The spring at Hudson has already been mention- 
ed. Another occurs at low water mark on the bank of the Hudson, a 
half or three-fourths of a mile north of Barnegat. Another flows from 
the side of the post road, a quarter of a mile north of the crossing of the 
Caspar kill. Another, on Judge Bockee's farm, in North-East, delivers 
about 20 cubic feet per minute. The water is very clear, and uniform 
in temperature through the year. 
In Pine Plains are several large springs. Two are located on Mr. 
Walter Reynolds' farm, about three miles east of Pine Plains. Both of 
them are, in fact, subterranean streams, which sink into the earth and 
re-appear. The larger stream disappears in a sink-hole in the base of 
the hill, on the north side of the road from Pine Plains to Pulver's 
Corners, and re-appears as a large spring boiling up through sand about 
a quarter of a mile southwest of the place of its disappearance. There - 
is a sink-hole on the line between these places, where the earth sunk in 
a few years ago. Mr. Reynolds, who has done much to develope the 
local geology of that vicinity, pointed out these and many other inte- 
resting geological facts. 
