534 
GEOLOGY OF THE FIRST DISTRICT. 
at the laumonite locality,* about one hundred to two hundred yards below Phillips’s mill, one 
and a quarter miles east-northeast of West-Point. 
The hornblende rock is common on Bull hill, the mountain north of Coldspring. 
The same rock, associated with hornblendic gneiss, was observed on Mount Stessing, near 
Pineplains, Dutchess county ; and on the mountains in Pawlings, in the southeast part of 
Dutchess county. 
The hornblendic rocks are constantly associated with the beds of magnetic oxide of iron, 
which are so numerous in the Highlands. 
(B). PRIMARY ROCKS OF ORANGE AND ROCKLAND COUNTIES. 
“ The Primitive region of Orange county extends from Butter hill in the town of Cornwall, 
along the Hudson river to Fort Montgomery; thence along the line of Rockland county, to 
the State of New-Jersey; thence along the New-Jersey line, to the western base of the Po- 
chunk mountain, about one mile southeast,of the Walkill. 
“The northwestern border of the primitive is very irregular, extending obliquely across the 
county near its middle, in a direction about east and west. It embraces a large portion of 
the town of Warwick, most of the town of Monroe, the south corner,of Goshen, part of 
Blooming-grove, nearly all Cornwall, and parts of New-Windsor and Newburgh. By far the 
greatest part of this primitive region is composed of gneiss. In many places it is regularly 
stratified, the line of bearing being on an average S. 45° to 50° W. and N. 45° to 50° E., 
and the dip to the south and east at an angle varying from forty-five degrees to nearly verti¬ 
cal. There are, however, many variations, both in the direction and the dip, but they are 
local. This rock, in some of its varieties, forms the great mass of the Highlands. For ex¬ 
hibitions of the stratification and dip, many fine examples are seen on the Orange turnpike, 
and on the turnpike from Canterbury to the New-Jersey line. The local variations may be 
observed at Sterling mine, and on the road from Canterbury to West-Point, and many other 
places. It is presumed that the variations in the dip, to be seen on the last mentioned route, 
induced Prof. Eaton to believe that all the primitive rocks of the Highlands in this county 
dipped to the northwest.! In general, the primitive rocks of the county are less regular in 
• This locality of laumonite and stilbite has been said to be exhausted. It is not. It is a vein of decomposing felspar, two 
and a half to four feet wide, in which the laumonite and stilbitb' crystals abound. I had a blast put in the vein in 1829, and 
obtained an abundance of specimens showing these small but perfect crystals, in groups, in the cavities of the felspar. Many 
wagon loads could probably b^ obtained. Much of the felspar is dark-colored glassy felspar, 
t Vide American Journal of Science, 
