Geological Survey of the State of New York. 101 



©n the west, and between mounts Adam and Eve. It contains 

 beds of granite, quartz, hornblende, and augite rock, and is unstra- 

 tiiied. The minerals found in. this are similar to those enumera- 

 ted above, and they are among the riches of American cabinets. 



The Island of New York, as described by Dr. Gale, contains 

 elevated ranges of granite and gneiss with imbedded rocks, a lim- 

 ited range of limestone on the north, while the southern portion 

 is covered with " from ten to eighty feet of diluvium, resting on 

 the same or* greater thickness of alluvial or tertiary sands, which 

 last are highly stratified and even exhibit the appearance of rip- 

 ples as from the retiring waves of the ocean," 



The most interesting portion of the report is that describing the 

 bowlders and diluvial scratches. The bowlders are found in the 

 greatest profusion and variety, and consist of greenstone in abun- 

 dance — a rock that is not found in place on the island, nor nearer 

 than the Palisades of New Jersey on the west, or on the east than 

 Southbury, Conn., and the ranges of Connecticut River valley 

 that terminate at New Haven, There can be little doubt that 

 they came from New Jersey, in accordance with the general evi- 

 dence of a current from the N, W. to the S, E., and yet although 

 they have passed but this short distance, they are always rounded 

 and covered all over with grooves and scratches. They are from 

 ten to fifteen feet in diameter. In many parts of the city they 

 have been removed by the process of grading the streets ; but in 

 the front of Brooklyn heights, they may be seen in great num- 

 bers, when excavations are made for erecting buildings. Others 

 are of 



Red sandstone^ a rock not found in the island, but limited to 

 the same localities above named, underlying the trap. 



Serpentine, of Hoboken, particularly in the south part, and at 

 Corlaer's Hook and Brooklyn. 



White limestojie, as from Kingsbridge. 



Granite and gneiss, as abundant as greenstone, in every por- 

 tion except the north extremity of the island. Those from ten to 

 twelve feet in diameter are common, and one of granite, eleven 

 feet diameter, "near Manhattanville, on the Bloomingdale road, 

 rests on the gneiss," which is covered with diluvial grooves, and 

 a very large one, three inches deep and eighteen inches wide, be- 

 tween the road and the bowlder, and terminating at the bowlder, 

 seems to have been caused by the movement of this huge mass." 



