by
arrow), and southerly through eight or nine low passes between Maple
Grove and Prospect Park to the frontal plain, the ice close to the
moraine arresting any escape of the waters into New York Bay north of
the Narrows.
Professor
Woodworth has described a College Point delta resulting from a retreat
of the ice front from its Port Washington position, involving a
changed outline to the glacial embayment and possible escape of its
waters through the northwestward course of Newtown Creek to the East
River at Hunter's Point, or, " if that way was still blocked by the ice
sheet, along a more southerly course between Williamsburg and Brooklyn
into Wallabout Bay," while from Wallabout Bay a winding passage
permitted discharge into Gowanus Bay, north of the Narrows.
The
morainal contributions to Brooklyn topography are unmistakable, and
long after the main ice-sheet had receded, outliers, melting in
self-created depressions, formed upland lakes, or through the erosive
action of the waters, from their dissolution, parceled out and
stratified the confused debris around them. The recent period
succeeded, with perhaps a sinking coast line of the island, wave action
along its shores, growth of spits, bars, and narrowly enclosed bays. As
illustrating its mutations of level, and phases of condition, only
recently in Fulton Street at the corner of Hoyt, at a depth of 45 to 50
feet, beach sand was uncovered with shells of the hard-shell clam (Mercenaria) and common oyster (Ostrea): (Charles O. Zeller).
The
water-bearing beds are in the Cretaceous and Pleistocene (Quaternary)
gravels; the porous character of the ground on Long Island favors the
percolation of the waters, and evaporation is reduced; there are
flowing or artesian wells, but not commonly, on the island, and the
"perched water tables," as in the Mountain Mist Springs in the West
Hills, are due to elevated impervious clay beds with a higher
watershed about or behind them. On the West Hills the springs are 280
feet above sea level, but the land rises behind them
