546 
GEOLOGY OF THE FIRST DISTRICT. 
No. Remarks on the direction, etc. Yards. 
6 South---- 100 
7 S. 30° W. to south point of second Wagon’s island- 15l5 
The marsh extends between these islands, and southwards to the main land half to 
three-quarters of a mile. 
The flats extend from the south shore about S. 20° E. to the base of the Dunderberg 
mountain, and are covered with water except at extremely low tides_1500 
8 S. 40° E. Granite and gneiss----200 
9 S. 40° E. (Granite on this course)-- 300 
10 South. Granite and gneiss to the point of Dunderberg- 100 
11 S. 10° W. Flats and beach (narrow) on shore. 
12 S. 25° W. to W’'ard’s wharf at Caldwell’s landing-250 
The quaternary hills here line the shore, and form a bank or terrace about seventy to 
one hundred and twenty feet high, between the shore and the Dunderberg mountain. 
Stony point, two or two and a half miles below Caldwell’s landing on the right bank of 
the Hudson, a place of some celebrity in the history of our country, has already been spoken 
of as having fine granite, which is traversed by dykes of greenstone, and hornblendic rocks 
also traversed by trappean dykes and veins. A considerable portion of this peninsula, which 
is properly an island, connected with the main land by an alluvial salt marsh, is composed of 
hornblendic gneiss like that on the eastern shore of the Hudson, a mile and a half below 
Verplanck’s point. As we progress westward from the point, it becomes the sienitic rock, and 
finally the pure hornblende rock in some places. The similar rocks on the eastern side of the 
Hudson bear about N. 70° E. of these. The hornblende rock on a hill on the north shore of 
Stony point peninsula, crumbles into a black hornblende sand, and many slight excavations 
have been made with the hope of finding iron ore in this hill. The rock is very heavy and 
black, and the color and weiglit of the rock have induced the expectation. Coal has also 
been expected here by those who have been misled by the black color of the rock. 
Many interesting magnesian minerals occur here, connected with the dykes in the horn¬ 
blende, and the seams of the rock for several rods from the dykes. They are very similar 
to those of the serpentine rocks of Staten island and of New-Rochelle. The other rocks of 
this vicinity have already been described under the Taconic system, the Metamorphic rocks. 
Red-sandstone and Trappean divisions. This vicinity is one of the most interesting and in¬ 
structive localities for the student of geology. 
The Colaberg and Buckaberg mountains lie to the southwest of the Dunderberg; they are 
composed of gneiss and granitic rocks. Near the turnpike gate on the top of the mountain, 
the strata are vertical, and more or less streaked with hornblende. Farther west, they are 
sometimes vertical, and sometimes dip easterly seventy to eighty-five degrees. 
On the western declivity of the eastern main range of the mountains, in descending into 
Kyle’s valley (through which Stony brook flows south-southwest into the Ramapo at Slote- 
burgh), the stratification was observed for a short distance to be transverse to the general 
direction (nearly east and west); but in a few rods on either side, the regular direction of 
N. 30° E. was resumed. 
