178 
GEOLOGY OF THE FIRST DISTRICT. 
A boulder of limestone, weighing a ton or more, was dug from a well in the hilly region 
(the gravel and loam hills of drift) of the interior of Staten island, from a depth of about 
sixty feet. It was replete with fossil shells, and was similar in chemical composition, mine- 
ralogical structure and texture, and in its fossil remains, to one of the strata of the Helderberg 
limestone series, and which extends from the Helderberg mountains west-southwest of Albany, 
in a southeasterly direction to near Coxsackie, thence south to Kingston, thence southwest 
through the Mamakating valley to Carpenter’s point on the Delaware. This belt of rock, 
and an outlier of the same at Hudson, are the only rocks of the kind known so near, except 
in a westerly direction across the mountain ranges on and beyond the Delaware river. A 
specimen of this rock is preserved in the State Museum at Albany. 
In the interior of Staten island, a boulder of limestone filled with fossil shells, and similar 
to that of Becraft’s mountain near Hudson, was dug from a well at a considerable depth. A 
boulder of siliceous limestone, like one of the strata of the Helderberg, containing fossils, 
was dug from another well on Staten island. These boulders were seen by Mr. Hazzard, 
who gave me specimens of these blocks, which he had preserved. I found a small boulder 
of decomposed rock on the shore near the southwest light-house, filled with fossil remains 
similar to those of the middle limestone of Becraft’s mountain, Columbia county. Dr. James 
Pierce describes petrifactions of marine shells in rocks excavated on Staten island, twenty 
feet below the surface, and sixty above the ocean.* 
The city of Nevv-York is built partly on the drift deposits (particularly the northern), and 
other portions on the quaternary, alluvial and primary. The drift deposits are daily exposed 
to observation by digging wells, foundations of buildings, grading streets, and cutting down 
the hills to obtain materials for filling up the lower ground and marshes. The materials of 
the drift consist of boulders, pebbles, gravel, sand and loam, composed of granite, gneiss, 
sienite, mica slate, hornblende rock, crystalline and compact trap, serpentine rock, steatite, 
red sandstone, grey grits of the Hudson slate series; white, blue, grey, compact and crystal¬ 
line limestones of various geological ages, some of which contain fossil remains ; and slate of 
various kinds, as blue, red, green, talcose and chloritic. 
The above mentioned rocks I had observed as boulders in 1828-9. Prof. L. D. Gale was 
employed in 1838 to make a geological examination of New-York island; and as his observa¬ 
tions have been more minute than my own, I will quote him on the boulders. I consider his 
observations very important, in consequence of the strong evidence they afford on the point 
under investigation ; and although there are some local irregularities in the direction of the 
distribution of the boulders, it is believed that they will all harmonize, when all the facts shall 
have been brought forward that have been observed. 
Prof. Gale, speaking of the boulders of New-York island, says : 
Silliman’s Journal, Vol, 1, p. 145. 
