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110 GEOLOGY OF NEW YORK CITY
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cates
now found distributed in nests, broken reticulated seams, or dispersed
scales and individuals in the dolomite. Such minerals are tremolite
(malacolite), diopside, biotite, tourmaline, while silica crystallized
in geode-like cavities as smoky or pellucid quartz. The chemical
opportunity was the moment when sufficient mobility was given to the
elements by heat to enter into new combinations and form these
accessory mineral species at the same time that the calcareous and
magnesian muds hardened and crystallized into their present form.
WATER-WAYS
The
different sections of Greater New York are separated from one another
by water-channels, all of which are subordinated to the large central
stream of the Hudson River. The Hudson River, as a topographical
feature, quite overshadows the neighboring tidal affluents. But at the
city of New York this river has utterly lost its fluviatile character.
It has been drowned, absorbed, and overwhelmed by the invasion of the
ocean; along with the other water-ways it is an aisle over which the
ingression of the sea is marked by two maxima and two minima heights
daily. Before this practical submergence, when the shore lines were
more elevated, its expansion into any lake-like basin, such as the
Upper Bay, was probably far less conspicuous. It then became, indeed, a
conditioned current, pressing its way between the headlands, facing
each other, of Long Island and Staten Island as it escaped the coast
line into the Atlantic Ocean.
Its
former course was prolonged over a wide coastal plane reaching the edge
of the continent some eighty miles from the Narrows. It is now at this
point submerged by the invading waters of the ocean, which form of all
the channels about New York, as well as the lower reaches of the
Hudson, a network of tidal areas. The coast has subsided, and the
estuarine limits of the Hudson, the Passaic, Hackensack, and Housatonic
Rivers have been pushed inland.
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