530 
GEOLOGY OF THE FIRST DISTRICT. 
Much of the gneiss jn the Highlands of the counties under consideration is a hornblendic 
gneiss, in which the mica is wholly or in part replaced by hornblende. 
A range of granitic gneiss, of a light color, passes through Putnam and a part of West¬ 
chester county. It extends through Carmel, near Pine pond, by Mahopack pond; thence 
southwardly, and crosses the turnpike from Peekskill to Danbury. Another bed extends from 
Boyd’s corners in Putnam county, and crosses the Peekskill and Danbury turnpike about 
live or six miles from the former place. These beds are quarried, to a small extent, for use 
in the vicinity; but they are too remote from water transport, for quarrying at present for a 
more distant market. It is durable, of a light grey color, easily split from the quarry, and 
easily dressed. If these strata reach the Pludson river, they are believed to have changed so 
much in aspect and quality as building stone, as not to have been recognized as the same 
beds. The bluish gneiss is quarried at Gen. Van Cortlandt’s quarry, near Roya hook, two 
miles west'of Peekskill. The strata here dip thirty or forty degrees to the east-southeast, 
and are interlaminated with beds of reddish and grey granite. Another quarry is opened near 
Peekskill landing, half a mile northwest. 
A range of reddish gneiss extends north-northeast from the point above Tarry town. In 
many places excellent quarries may be opened, where the stone quarries well, dresses easily, 
and is beautiful and durable for architectural purposes. One quarry is already worked to 
some extent in this range, for the New-York market, on Mrs. Beekman’s farm, about one and 
a half miles from Tarrytown. Large quantities of stone are taken from this quarry, to be 
used in the construction of the culverts and bridges of the aqueduct that leads from the Croton 
river to supply the city of New-York with water. 
Numerous other quarries have been opened along the line of the aqueduct, in the bed of 
gneiss just spoken of, and in others, to supply stone for this great work. It is not doubted 
that several of these quarries, which lie near water transport, will be wrought for the New- 
York and other markets. Our citizens do not yet appreciate the prospective value of good 
quarries on the banks of the Hudson river. 
Another range of gneiss, suitable in many places for quarrying, extends from near Manhat- 
tanville on New-York island, by Whiteplains, and so on north-northeast, probably into Con¬ 
necticut, or Putnam county. It enters the valley of the Bronx river about eight or nine miles 
below Whiteplains, while it forms a part of the range of the hills on the right bank of that 
stream for several miles below. 
At one locality in this range, the rock is quarried to some extent, to furnish the stone for 
the aqueduct bridge across Mill river, near Yonkers or Phillipsburgh. It is an excellent, 
beautiful stone, but rather hard to dress. This stone will last as long as it will be required 
to endure, and it seems indestructible. 
A gneiss quarry has been opened two miles east of Yonkers, on the land of Elijah Valen¬ 
tine. The rock is of a superior quality, and is used in the construction of arches in the aque¬ 
duct. The proprietor receives a rent of twelve and a half cents per cubic yard for the stone. 
Gneiss, both fissile and thick-bedded, was seen at the landing at New-Rochelle, and on 
