162 ■ (Ujologij of JUclntioiid CoKiiti/, S. Y. 



prs and pebbles, gravel, clay and sand, — with little or ncr order 

 of arrangement, — which materials have been bronght from the 

 north and northwest by the great glacier which, in post-tertiary 

 times, overspread ISTorth America sonth to abont the fortieth 

 parallel, and had its sonthern extension along the Atlantic coast 

 on Staten Island. East of the Narrows,, these hills form the 

 backbone of Long Island ; and west of Perth Amboy, they have 

 been traced entirely across the State of New Jersey, and indeed 

 all the Avay to Missonri and Kansas. They are what is known 

 as the terminal moraine of the North American glacier. 

 - East of the ridge of magnesian rock, and sonth of the moraine, 

 we have some nearly level plains ; these are well shown near 

 New Dorp and Garretson's Stations, and again at the extreme 

 southern end of the island. The surface is also quite level from 

 New Spriugville to Mariners' Harbor. 



Extensive areas of salt meadow^ occur along the Lower Bay 

 near New Creek and the Great Kills, along Arthur Kill from 

 liossville to Port Richmond, and small patches near Totten- 

 ville. 



There are no streams of very considerable size on Staten Island, 

 but brooks and ponds are abundant. The largest of the latter 

 is known as Silver Lake, and is situated high up on the mag- 

 nesian hills, one mile and a half west of Stapleton. 



According to the observations of Mr, Charles Keutgen, the 

 total rainfall in inches for the last ten years, at Stapleton, has 

 been as follows : — 



1870 : 



38.38 



1873 : 



53.09 



1876: 



46.09 



1879 : 



47.16 



1871 : 



53.45 



1874: 



49.68 



1877: 



42.90 



1880: 



37.34 



1872: 



45.00 



1875: 



45.00 



1878: 



58.62 







Literdture of Ike Siihject. — The subject of the Geology of 

 Richmond County has been considered principally by the follow- 

 ing writers : — 



W. B. Mather, in the "Geology of the First District of New 

 York," refers to Staten Island in a number of different places. 

 Mather considered the clays and sands of the southern part of 

 the island to be of Tertiary age. and the magnesian rocks to be 

 of igneous origin ; both of which conclusions are now replaced 

 by others, probably nearer the truth. 



