dike
on Staten Island indicates a probably similar position of origin, and
so enables us to assume that this primary rock at considerable depths
forms the basement flooring of the western sections of the borough. So
in relation to the assumed fundamental platform of rocks upon which
all the later formations of Staten Island rest, of which platform the
granite vein at Tompkinsville was a suggestion, a platform likewise
continuous with the schists of Manhattan Island, and like them possibly archaean in age, there is some significance to be given to this trap dike.
This
dike can be traced from Elm Park (north shore) back into the island for
over five miles, forming a low swell, and either' bending or
bifurcating toward Long Neck, disappearing beyond Linoleumville in the
waters of the Arthur Kill.
The
Cretaceous Formation appears next above the Trias-sic, and doubtless
forms a large part of the borough extending southward and eastward. It
is represented by beds of sand and clay, the latter black, white,
yellow, and brown, which outcrop, or have been uncovered in
considerable force at and near Kreischerville. (Fig. 42.) Lignite and
vegetable remains appear in these beds, but a really satisfactory
source of fossil plants has been discovered in the concretions of clay
cemented by limonite (hydrous iron oxide). These oval, flat, or
circular nodules have been dislodged at various points along the
southern and eastern borders of the island, and their contents, both of
plants and shells, have proven, by their cretaceous affinities, the
probable age of some bed or beds from which they were derived. Dr.
Arthur Hollick has industriously investigated these " finds," and the
evidence, now accumulating for many years, approaches almost
demonstration of the widely extended area of these cretaceous deposits.
They are a part, along the coastal shelf, of the same formation in New
Jersey, and are continued eastward through Long Island; a series of
beds dipping to the southeast and representing the final assortment of
the products of decomposition of granite
