92 HOLLICK. 



about the center of the island, at Richmond. The eastern and 

 southern border of this ridge is abrupt, in places forming a 

 steep escarpment and reaching a maximum elevation of 380 

 feet, at a point distant about a mile from the border. From 

 the summit of the ridge to the north and west the surface is an 

 irregular slope to tide water at the shores of the kills, which 

 separate the island from the adjoining mainland. A low trap 

 ridge is the only other well-defined rock exposure in this re- 

 gion. The plain region comprises the remainder of the island. 

 It is an isolated portion of the Atlantic coastal plain, over the 

 greater part of which is spread a series of morainal hills with a 

 maximum elevation of 175 feet. The underlying strata are 

 Cretaceous. Almost the entire area of the island is covered by 

 boulders, till or modified drift. 



TERMINAL MORAINE. 



Earlier Descriptions. 



Probably the earliest published account of the drift on Staten 

 Island is in a communication from Mr. James Pierce, to the 

 editor of the Amciican Journal of Science, in 181 8. In this he 

 says : " Large beds of water-worn siliceous pebbles, in no way 

 differing from those washed by the ocean, are seen on the 

 height of the ridge, in which excavations have been made sev- 

 eral feet, leaving the depth of the mass uncertain. * * * Adja- 

 cent to Fort Tompkins, detached pieces of copper ore have 

 been found. I have observed petrifactions of marine shells 

 in rocks excavated in that neighborhood, twenty feet from the 

 surface and sixty above the ocean." 



In 1838 Mr. W. W. Mather's preliminary report on the geol- 

 ogy of New York was issued, in which he mentions the occur- 

 rence of fossiliferous boulders on Staten Island, as follows : " A 

 boulder of limestone filled with fossil shells, and similar to that 

 of Becroft's Mountain, near Hudson, was dug from a well at a 

 considerable depth. A boulder of siliceous limestone, like one 

 of the strata of the Helderberg, containing fossils, was dug from 

 another well on Staten Island. * * * I found a small boulder 



