lands
against which the protruding ice sheet broke, and as it overrode and
enveloped them it parted with its Upper Devonian burden, to replace
them south and southeast of the Highlands with Triassic shale, sandstone, and trap.
The
Hudson River tongue of ice, or its particular stream of participation
in the universal sheet, could not have been so despoiled, and it left
the east central New York fossiliferous specimens as "erratics" on
Staten Island, and their original position was near the Hudson River
course.
This
conclusion seems fortified when we consider the prevalent eastern and
southern localities on Staten Island where these fossil boulders have
been taken. Out of 147 localities, 85 are eastern (Clifton, New
Brighton) and 52 are southern (Princess Bay, Richmond Valley,
Tottenville), or beyond the serpentine ridges, on a plain, over which,
by fanning, the Hudson River ice tongue might have spread.
The Triassic and Cretaceous fossils (the Triassic are negligible) of the drift are involuted in the drift at
or near the place on the island where the Cretaceous occurs, and are
inclosed in concretions. (For detailed nomenclature of drift fossils
see A. Hollick, Some Features of the Drift on Staten Island; Annals New
York Academy of Sciences, Vol. xii, p. 91.)
Long
Island, that narrow fork of land running eastward and separated from
the southern shore of Connecticut by the Long Island Sound, a shallow
and turbulent trough, is lined with boulders, while its backbone of low
hills is also strewn with their debris. They occur gathered together in
groups forming topographical features in the landscape, and single
ones have a weight of 2,000 tons. As regards their origin, they seem to
have drifted from three localities, from the Helder-berg Mountains in
north New York, from Manhattan Island, and from various points in Rhode
Island, Connecticut, and Massachuetts. Those about the east end of the
island may be traced to the Eastern States lying to the north, while
many of the western visitors appear to have approached along the valley
of the Hudson from the highlands of New York.
