338 Prof. Beck on Igneous Action, as exhibited in New York. 
two or three hundred yards near Port Richmond, and which 
ain appears at Bergen, New Jersey, and onward forms the 
Palisadoes of the Hudson. The connexion between this range 
and the serpentine is too obvious to need farther notice. 
Serpentine has been found on the island of New York, but not 
in large masses. On the peninsula east of New Rochelle in 
Westchester County, it is abundant, and has the appearance of a 
distinct dyke. Its structure is somewhat columnar, and it is 
every where traversed by seams of softer magnesian minerals, 
asbestus, &c. On the west, it is said to be bounded by horn- 
blende rocks, while on the east is a limestone more or less — 
with serpentine. 
_ Similar in their characters, are several deposits of serpentine in 
he counties of Dutchess and Putnam. At Brown’s quarry in the 
latter county, this columnar or basaltic appearance is well exhib- 
ited. The serpentine is here very dark colored, and varies in its 
structure from compact to coarse crystalline, like some hornblendi¢ 
rocks; to which, indeed, in hand specimens, it not unfrequently 
bears a close resemblance. The fissures contain crystals of horn- 
blende, plates of Schiller spar, and dark colored tremolite. 
There is a fine illustration of the intimate connexion between 
trap and serpentine, although upon a small scale, on Stony Point 
in the county of Rockland. Trap dykes pass up the northwestern 
face of this hill, which are well marked in consequence of the 
decomposition of the hornblende rock. Now these dykes ate 
every where traversed by a soft greenish substance belonging t0 
the serpentine family. They contain also asbestus in very deli- 
cate silky fibres. 
In Lewis County, near Natural Bridge, where trap dykes and 
trappean aggregates are not unfrequent, there are mural precipices 
made up chiefly of the substance called Rensselaerite by Dr- 
Emmons, but which I suppose to be a mixture of steatite or Sel 
pentine with pyroxene. The same mineral occurs in unbroken 
ledges in the vicinity of Ox Bow, Jefferson County, a region in 
which well characterized trap dykes are common. 
So also in St. Lawrence and Essex counties, whenever serpe 
tine is found in any abundance, dykes of trappean rocks are to be 
seen in the immediate vicinity. 
We have strong grounds, therefore, for adopting the theory of 
the igneous origin of serpentine, were we furnished only with the 
