TRAPPEAN DIVISION, 
281 
of Kedidica hook* is well calculated for geological and geographical survey, uniting extension 
with distinctness of view. The wood-clad highland chain is observed ranging the horizon for 
fifty miles ; its course is from northeast to southwest; the Newark and Pracknes mountains 
faintly appear to the southwest. The Haverstraw mountainf is near you, with its camel’s 
back summit running westwardly; to the south the Palisadoes are seen.”:|; 
The trappean range that disappears beneath tide water at Bergen point, the southern ex¬ 
tremity of the visible exposure of the Palisado range, reappears in a prolongation of the di¬ 
rection of that range on Staten island. It is a smooth, round-backed ridge or gentle swell of 
land parallel to the serpentine ridge, and is mostly covered with soil. It is elevated in its 
highest part one hundred and fifty or perhaps two hundred feet above tide water. It dis¬ 
appears to the west of Richmond, beneath the Freshkill marshes, and is not known to re¬ 
appear farther south on the island. The locality where I saw it best exposed, was at a quarry 
that has been called a granite quarry, the rock of which was described in the papers of the 
day as granite. It is a coarsely crystalline greenstone ; and though more difficult to dress than 
most cut stone, it is a beautiful and durable building material. The surface of the rock under 
the soil is smoothed, as if ground off by the cause that has produced the scratched surfaces 
of rocks. A set of fissures nearly vertical and ranging about N. 20° E., and another pa¬ 
rallel to the contour of the hill, traverse the rock, dividing it into flat masses, that may be 
blocked up by the quarrymen with much less labor and expense than they could be without 
these joints. The north and south vertical fissures are not as continuous or distinct as the 
horizontal ones; and these latter give the rock an appearance of indistinct stratification, with 
layers three or four feet thick. 
Near the southeast corner of Rockland county, a valley through the mural front of the trap 
rocks gives a passage for a road at Dobbs’ ferry. On the shore below the trap escarpments, 
trappean injections seem to have been made between some of the strata of sandstone, which 
have materially modified their color and texture, and almost changed their nature. Many of 
the strata, of a deep red color, seemed to be a modified trap, composed mostly of the finer 
materials of the sandstone, partially melted, and more or less amygdaloidal, with cavities 
which are either lined with crystals or filled with chlorophasite. This altered rock is some¬ 
times light red, deep red, purple, brown and black. Scales of micaceous oxide of iron were 
common in some places in these altered rocks. The sandstone dips west, northwest and south¬ 
west, at very small angles, at different points observed between the New-Jersey line and 
Tappan creek. 
The trap rocks on the shore of the Hudson, about two miles north of Nyack, stand in 
rude semi-columnar masses, with a nearly vertical escarpment, often like castellated ruins. 
The sandstone is frequently seen on the shore, underlying the trap. It is slightly inclined, 
dipping a few degrees in a westwardly direction. Some places were seen where we could 
trace within a foot or two of the actual contact of the trap and sandstone. The latter, near 
» Same as Verdrietige hook. 
t Pierce. 
+ The trappean range from the High Tom west and southwest, 
American Journal of Science, Vol. 2, pp. 187-8. 
36 
Geol. 1st Dist. 
