SURVEY OF THE ISLAND OF NEW-YORK. 
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cation. The marble, as stated, commences at the valley (204th-street), where the lime 
mingles with gneiss; has a strike N 30° E ; dip vertical. The limestone is from fifty to 
eighty yards in width, gneiss contiguous on either side, and at a distance of eighty or one 
hundred yards from the road. As it continues northward the limestone widens, following a 
line westward of, and nearly parallel with the road, but often appearing under the road, and 
on the eastern side of it, until it has widened to four hundred or six hundred yards ; and after 
continuing northward from the valley above named about half a mile, the gneiss on the Hudson 
runs out, and the whole ridge becomes limestone nearly opposite to, or rather a little beyond 
Tubby hook, on the Hudson (Vide PI. 30, fig. 7). The general direction of the strata is 
N 25 to 30° E, and dip E 60 to 75°, and occasionally vertical. 
North of Mr. Dykeman’s farm, which is about one mile from the northern extremity of the 
island, are situated a series of abandoned quarries of limestone, which have been successively 
wrought for lime and abandoned within the last thirty or forty years, not one of which, to my 
knowledge, is now wrought to any extent. The strike is on an average N 45° E, and dip 
45° E, somewhat tortuous. The first of the abandoned quarries (the south) is six hundred 
to eight hundred feet north and south, or in the direction nearly northeast and south-west. 
Again a few rods north of the old tide-mill, which is in a natural valley which interrupts 
the chain of hills constituting the limestone formation of the vicinity, and is represented on 
the sketch (PL 30, fig. 7), the limestone occurs, containing a stratification of gneiss, with a 
mixture of gneiss and limestone. Strike N 45° E. Dip E 45°. The rock is of an inferior 
quality, but withstands the elements well; and the same quality of rock seems to extend to 
the northern extremity of the island, but it has been very little wrought northward of the 
tide-mill; but from this point southward to near Mr. Dykeman’s house, a distance of more 
than half a mile, and on the west side of the road, are found all of the abandoned quarries 
which were formerly wrought for burning into lime. 
From the old tide-mill, on Nichols’s canal, to the northern extremity of the island, the whole 
ridge narrows so much that it is not more than from one hundred to five hundred yards in 
width, and from ten to thirty yards in height. 
The marble from Kingsbridge and its vicinity, is all of an inferior quality, from the fact 
that the grains composing it are possessed of so little cohesion that it disintegrates and falls 
to a calcareous sand. It has been called magnesian limestone, and I know of no analysis that 
has been made of it, but I think it desirable that in either case an analysis should be made. 
The rock contains pyrites to a considerable extent, so that after long exposure it becomes 
oxidized, and the whole is covered to such an extent as to give it a yellowish cast. It contains 
cross veins of white pyroxene. 
228th-street is the northernmost street on the island. 
Returning from Tubby hook to Manhattanville, or from 200th-street to 126th-street, on the 
west side of the island, we found comparatively few interesting geological facts to claim 
Geol. 1st Dist. 76 
