the
bluff has an altitude of about seventy-five feet (Fig. 50). It declines
landward into an undulating plain, which largely represents drift
reassorted by water.
There
is a morainal bank setting round the serpentine eminences and riding
up and over their slopes from Tompkins-ville to West New Brighton on
the north shore. Its lower portions, where cut through, show a stiff
till formation. It has been broached and escarped by waves and water,
and now forms a prominent terrace on the south shore of the Kill van
Kull channel, declining to tide-water where an interior northward
drainage at Snug Harbor has cut through and reduced it. Formerly its
discharged contents crowded the shore with boulders.
The modified aspect of the drift is quite contrasted with the exhibitions of its unmodified character-
seen on Long Island and alluded to above. A very admirable
demonstration of this latter is afforded by the cut, for instance,
through the Coney Island Railroad passes, on an ascending grade, from
Bay Ridge. The hill also at Prospect Park was, not many years ago, far
more extensive, covering the tract through Park Place. It is gradually
being lowered, and the numerous cobble-stones recovered from it are
broken and crushed and used in asphalt pavements. The iron and lime in
the morainal mixture frequently form a cement, and bind into rigid
conglomerate the pebbles and cobble-stones. The relative positions of
the included stones often show the absence of rearrangement of the
moraine by water, since the heavier stones remain in zones above the
smaller and lighter ones below.
It
will repay the teacher to take a handful of the smaller fragmental
material of the moraine and, washing the earth or clay from it, note,
under a hand-glass, the stone particles remaining, and attempt an
enumeration of their kinds.
In
the bluff at Princess Bay Light there is an underlying detrital mass of
stones and sand which Professor Salisbury assigns to the "Pensauken
formation," of which he says:
