284 
GEOLOGY OF THE FIRST DISTRICT. 
The range of serpentine on Staten island is in a prolongation of the direction of that form¬ 
ing the shore of the Hudson between Wehawken and Hoboken ; and it is said to form some 
of the reefs, and the substratum of Ellis island, between Hoboken and Staten island. Ser¬ 
pentine rocks, somewhat dissimilar in mineralogical character, are found in various parts of 
the First geological district; but as they are associated with trappean and other rocks among 
those usually classed as 'primary, these examples will be described under the head of Pri¬ 
mary rocks. 
On Staten island, the serpentine rock assumes a great variety of aspects, from black to 
nearly white, through various shades of green and yellow, and from compact to earthy. Some 
of the talcy varieties are called soapstone, by the people. Talc, carbonate of magnesia and 
hydrate of magnesia abound in it, and the rock might be used with profit in making magnesian 
salts and fire bricks. Asbestus and amianthus are not rare in it. This rock sometimes 
assumes an aspect almost like trap, but its specific gravity is much less. Some of the rock 
is much like meerschaum. 
Amianthus and asbestus are constant associates of our serpentine rocks; and on Staten 
island, it is possible that it may be obtained in quantities for useful purposes. 
Dr. James Pierce described the amianthus of Staten island in 1818.* He states that “ it 
breaks up like flax, and may be spun and woven without the aid of moisture ; and in respect 
to tenacity, flexibility, and length of fibre, it may be considered the best found in this country, 
and perhaps equal to any hitherto discovered.” Prof. Silliman remarks upon the above, “ The 
specimen of amianthus referred to in Mr. Pierce’s communication, is uncommonly beautiful. 
The fibres measure twelve and fifteen inches in length, and are as soft and flexible as fine 
human hair.”! The value of this material is well known. It has been principally employed 
in making incombustible cloth for firemen’s dresses. It would be more extensively useful in 
making indestructible paper for public records. The amianthus of Staten island is believed 
to have been used only as mineralogical specimens. 
No facts have been observed that lead to a definite determination of the epoch of the for¬ 
mation of the serpentine rocks, further than that, like the trap, it preceded the deposition of 
the drift, as boulders of both are numerous in proportion to the relative areas of these rocks 
exposed ; and that it may be presumed to have hteo. posterior to the deposition of the potter’s 
clay formation and the associated gravel beds, as no pebbles of these are remembered to have 
been observed among those deposits. 
Pebbles of serpentine were occasionally seen in the upper beds of the Long-island division, 
helow the drift deposits. At the time I was investigating the strata of Long-island, the im¬ 
portance of such facts in the determination of the eras of the eruption of the trappean rocks, 
was not impressed on my mind; but it is presumed, that had pebbles of those rocks been 
abundant, or even sparsely distributed in the pebble beds of the potter’s clay formation, they 
would have been observed, and noted in my diary of geological notes. The facts^ that will 
American Journal of Science, Vol. 1, p. 54. 
t Idem, p. 55. 
