METAMORPHIC ROCKS, 
459 
would be equally durable and easily wrought. It is composed of felspar and hornblende, and 
sienite or greenstone would be an appropriate name. It is generally about as coarse grained as 
the Quincy sienite; but some beds of the rock contain a considerable quantity of magnetic 
oxide of iron in grains, so that it exercises a strong influence over the magnetic needle. This 
may be seen very distinctly near the little islands of this rock east or southeast of Verplanck’s 
point. These hornblendic rocks that contain magnetic oxide of iron, disintegrate more 
readily than the others, and form a red soil. Some of the hornblendic rocks near the lime¬ 
stone and east of it, are hornblende slate and hornblendic gneiss. 
About two miles below Peekskill, the hornblendic rock is succeeded by limestone, which 
is generally, though not always stratified. In some places the limestone is contorted in almost 
every variety of form that can be conceived, and is more or less intermixed with augite, 
tremolite, mica, etc. 
Near the place where the limestone is first seen on the shore, proceeding from Peekskill to 
Verplanck, it is in very, thin layers. In some places these layers are nearly plane ; in some, 
arched ; in others, crumpled in every way with zigzag and winding layers, as is represented 
on Plate 9, figs. 16, 19 ; Plate 10, fig. 13 ; and Plate 30, figs. 1,2, 3. The limestone, where 
it is so much contorted, seems loo impure to be burnt for lime ; but farther along the shore 
towards Verplanck, the rock becomes more massive. The rock is white, grey and variegated 
in color. 
The rocks below Verplanck along the shore are hornblendic, and like those described as 
lying east of the limestone. They consist of sienite, hornblendic gneiss, hornblende slate, 
with veins and interstratified masses of reddish granite, and extend to within about one-quarter 
of a mile of Mr. H. J. Cruger’s mansion, where mica slate succeeds, and continues to near 
Mr. C.’s. The mica slate is succeeded on the east by a bed of white limestone of much 
economical importance. It is about three miles southeast of Verplanck, and forms the shore 
half a mile east or southeast of Mr. C.’s mansion, and it extends eastward from the shore into 
the interior. Some of it is adapted for a marble, which may be obtained in blocks of considera¬ 
ble size on the shore. It is already quarried for lime, the stone for which is shipped to New- 
Jersey, where it is burnt for the New-York market and for manure, with dust anthracite coal, 
at a small expense, and with a handsome profit. The stone is sold to the vessels at thirty- 
seven and a half to fifty cents per ton on the shore where it is quarried. 
This bed of limestone forms the shore of Haverstraw bay for more than a mile, extending 
from the mouth of the brook near H. J. Cruger’s sawmill, to the mouth of another small 
brook on Nicholas Cruger’s farm. 
Some estimate of the value of these limestone beds may be formed from the fact, that the 
blocks can be swung on board sloops by means of cranes, M'ithout any land transport, and 
that each acre may be made to yield from one hundred thousand to five hundred thousand 
barrels of lime ; or for shipment, each acre will, on an average, yield about one hundred 
thousand tons of stone suitable for burning. 
This limestone bed is succeeded on the east by hornblendic gneiss, with heavy beds of 
reddish granite. Plate 14, figure 7, shows a section of the rocks as far as observed between 
Verplanck’s and Cruger’s points. 
58* 
