nally laid down.

"The rock of New York Island is gneiss, except a portion of the north
end, which is limestone. The south portion is covered with deep
alluvial deposits, which in some places are more than 100 feet in
depth. The natural outcroppings of the gneiss appeared on the surface
about 16th Street, on the east side of the city, and run diagonally
across to 31st Street on 10th Avenue. North of this, much of the
surface was naked rock. It contains a large proportion of mica, a
small proportion of quartz and still less feldspar, but generally an
abundance of iron pyrites in very minute crystals, which, on
exposure, are decomposed. In consequence of these ingredients it soon
disintegrates on exposure, rendering it unfit for the purposes
of building. The erection of a great city, for which this island
furnishes a noble site, has very greatly changed its natural
condition. The geological age of the New York gneiss is undoubtedly
very old, not the Laurentian or oldest, nor the Huronian, but it
belongs to the third or White Mountain series, named by Dr. Hunt the
Montalban. It is the same range which is the basis rock of nearly all
the great cities of the Atlantic coast. It crosses New Jersey where it
is turned to clay, until it appears under Trenton, and it extends to
Philadelphia, Baltimore, Washington and Richmond, Va., and probably
Boston, Massachusetts, is founded on this same formation.

* * *

Oh, river! darkling river! what a voice
Is that thou utterest while all else is still!

_William Cullen Bryant_.

* * *

"On the opposite side of the river may here be seen for many miles the
Palisades, a long, rough mountain ridge close to the water's edge. Its
upper half is a perpendicular precipice of bare rock of a columnar
structure from 100 to 200 feet in height, the whole height of the
mountain being generally from 400 to 600 feet, and the highest point
in the range opposite Sing Sing 800 feet above the Hudson, and known
as the High Torn. The width of the mountain is from a half mile to a
mile and a half, the western slope being quite gentle. In length it
extends from Bergen Point below Jersey City to Haverstraw, and then
westward in all 48 miles, the middle portion being merely a low ridge.
The lower half of the ridge on the river side is a sloping mound of
detritus, of loose stones which has accumulated at the base of the
cliff, from its weathered and wasted surface.

"Viewed from the ra