304 SURFACE GEOLOGY. 



is interrupted at Neapeague beach and marsh, 12 miles west of Montaiilc point ; between 

 Manor and Yaphank ; and at Syosset. West from Roslyn it is very plainly recognized 

 as a continuous, irregularly undulating ridge. The heights of prominent hills in this 

 series are as follows : * RIontauk point, 85 feet above the sea ; Fort Pond hill, five miles 

 to the west, 194; Neapeague hill, 135; Amagansett hill, 161; Shinnecock hill, 140; 

 Osborn's hill, 293 ; Ruland's hill, south of Coram, 340 ; Jane's hill, the highest of the 

 West hills, 354; Layton's or Wheatly hill, 380; Westbury hill, 260; Harbor hill, 384; 

 John M. Clark's hill, near Manhasset, 326; Smith's hill, 332; Prospect hill in Brook- 

 lyn, 194. 



In the east and middle portions of the island the majority of these hills are composed 

 of modified drift, being gravel and sand, distinctly stratified, and containing few or rare 

 boulders. Osborn's, Ruland's, Jane's, and Harbor hills are of this kind. They appear 

 to be immense kame-like deposits, formed at the terminal front of the glacial sheet. 

 As at Cape Cod, when this was obliged to retreat, its melting took place over a very 

 wide extent of its surface ; and the rivers thus formed were heavily freighted with 

 gravel, sand, and clay, which had been contained in the ice. A large portion of this 

 gravel and sand would be heaped at the mouths of these streams, — that is, at the 

 points where they left these ice-fields and entered the lower open area beyond. 



The part of Long Island south of these hills consists of nearly level plains of fine 

 gravel and sand five to ten miles in width, and extending a hundred miles in length. 

 The height of their north portion at the foot of the hills varies from 50 to 150 feet 

 above the sea. These deposits, like the levelly stratified drift of Cape Cod, appear to 

 have been brought by the glacial rivers which formed the kame-like hills. The ocean 

 rolled its waves above the surface of these plains, spreading the material which it thus 

 received over a wide area to the south. 



Near the west end of Long Island this range of hills is composed entirely of unstrati- 

 fied glacial drift, full of boulders, having all the characteristics of the upper till. It is 

 well exhibited in the south-east part of Brooklyn by many excavations, as for cellars 

 and streets. This is the true terminal moraine of the ice-sheet. Its continuation east- 

 ward is for the most part covered by the later kame-like gravel and sand. Westward, 

 this terminal moraine, principally composed of coarse, unstratified drift like the upper 

 till, heaped in irregular hills and ridges, begins on the opposite side of the Narrows at 

 Forts Tompkins and Wadsworth, crosses Staten island, and enters New Jerseyf at 

 Perth Amboy ; it bends thence to the north-west and north, passing near Plainfield, 

 Morristown, and Dover ; next it runs west and south of west by Hackettstown to the 

 Delaware river a little above Easton. 



The boundary of the ice-sheet at its period of greatest extent appears to be thus 



* From articles on the geology of Long Island, by Mr. Elias Lewis, Jr., of Brooklyn, in American Journal of 

 Science and Arts, third series, vol. xiii, pp. 235 and 236; and in Popular Science Monthly, vol. x, pp. 434-446. 

 The greater part of these heights were determined by the United States Coast Survey. 



■f The course of these hills at the most southern limit reached by glacial action in New Jersey is from the 

 annual report for 1877, of Prof. George H. Cook, the state geologist. He says,—" The whole line of this mo- 

 raine is remarkably plain and well defined." 



