The
depth of water in the Lower Bay, south of the Narrows, over the shoals
or sand bars, is generally 8 to 18 feet, and in the channels which
thread or divide them it is 21 to 30 feet deep. Nearer the Narrows the
water deepens to 24 and 72 feet; in the Narrows the depth exceeds 120 feet, and thence northward in the main avenue or tirage of
the Hudson there is found from 30 to 72 feet, with lateral shallow
overflows towards the New Jersey and Long Island shores, where the
water is barely more than 18 feet deep.
The
overpowering influence of the ocean in modifying its issue has been
repeatedly pointed out as the tides and storms swing back and forth the
heavy burdens of sand along the coasts of Long Island and New Jersey.
Professor Lewis M. Haupt has discussed the projects which have been
carried on by the general government for improving the channels of the
Lower Bay. Up to 1886 the ruling depth on the bar was 23.3 feet at mean
low water, which permitted the passage at high water of a vessel
drawing 27 feet. Professor Haupt desired to influence the government to
adopt his method of improving this entrance by natural forces. This was
unsuccessful. It was concluded to resort to dredging to create a
30-foot channel, 1000 feet wide, which had been secured and maintained
after the removal, up to October, 1891, of 4,875,079 cubic yards at a
cost to date of $1,967,111.82. These depths not meeting the
requirements of the port, facilities were then increased by the
opening of the Ambrose channel, seven miles in length, crossing the
central part of the bar, by dredging therefrom 42,500,000 cubic yards,
under the provision that it should not cost more than $4,000,000, or
less than ten cents per yard.
Professor
Haupt, by means of charts covering a period of 125 years, has shown
that the inlet to Jamaica Bay has moved westwardly seven miles in that
time, and that the deposits which were formerly arrested in that bay
have now drifted past and are rapidly approaching the outer scarp of
the New York bar. This one bank of sand contains some 65,000,000
