Manhattan Island Geology | Gratacap: Geology of New York City Page 37



	MANHATTAN ISLAND	27

	East Rivers, on the south by the basin of New York Harbor, or the inter junction of the Hudson River and the East River channels. It preserves a fairly uniform width of two miles northward to 125th Street, and there tapers into an elongated neck-like extension, having an average width of three-quarters of a mile at Spuyten Duyvil Creek, its northern extremity. It is terminated at Spuyten Duyvil Creek by the wooded cliffs, denned to the beholder in spheroidal outlines by their covering of trees, as seen so attractively from the north side of the Harlem ship canal. Its lower end, on the other hand, is a flat, tongue-shaped projection, formerly, before occupation, covered with low hills or slopes of stony debris, and rounding quite symmetrically on either side into the channel of the East River and the Hudson on the west. The west margin of the island, through almost its entire extent, after the easterly inclination to the southern point is passed, is a straight line (formerly less regular), interrupted by slight irregularities, and a noticeable deflection westward at 153d Street. The eastern side of the island is less regular, and besides the lateral bulge at Grand Street, from Hell Gate at 92d Street to Randall's Island at 125th Street and thence to 155th Street, has variously curved and re-entering borders. This long strip, about thirteen miles in length through its longest axis, presented, before the occupation that has now covered it with houses, and which has extended its original shore lines, many contrasts along its margins to its present shape. Swamps and low ground inundated by tide water, and bearing a growth of salt marsh grass, extended along the eastern margin of the city at the foot of the present Broad Street and Maiden Lane (old "Fly Market"), while broad emarginations formed bay-like cavities, as at the region of " the Swamp," where Pearl, Water, Front, Gold and Ferry Streets form now the emporium of the leather trade. Again, the western end of Canal Street expanded into a water-covered area contiguous to the Lispenard meadows, whose alluvial deposits were connected by a stream or creek