QUARRY MATERIALS OF NEW YORK IO9 



mineral. The other important ingredients are feldspar and quartz. 

 The feldspar consists principally of microperthite and an acid 

 plagioclase, and is sometimes intergrown with the quartz. There 

 is a little magnetite but apparently no pyrite. The texture is even 

 granular, compact, scarcely differing from that of a normal granite. 



Quarries on Storm King mountain 



There are quarries on the southeastern face of Storm King 

 mountain, almost directly opposite those on Breakneck ridge. They 

 were once worked for building stone and paving blocks, and Smock 

 states that buildings in New York and Washington were erected 

 from this granite. A few years ago the Storm King Stone Co. 

 erected a large crushing plant here. No dimension stone has been 

 shipped for a long time. The granite is very similar in composition 

 and appearance to that on the east side of the river but carries some 

 biotite as well as hornblende. 



Old quarries, long since abandoned, exist on the south side of 

 Crow's Nest mountain, and on the next ridge to the south which is 

 partly occupied by the grounds of the West Point Military Acad- 

 emy. Some of the academy buildings are constructed of material 

 from these quarries. 



THE GARRISON GRANITE BOSS 



King's quarry 



A small area of massive granite is exposed north of Peekskill 

 between Manitou and Garrison in Putnam county. It lies within 

 the main gneiss belt that forms the more rugged part of the High- 

 lands as exemplified in the Hudson gorge section from Anthony's 

 Nose to Breakneck ridge on the east bank. The area is about one- 

 fourth of a mile back from the river and 2^ miles from Garrison, 

 a station on the New York Central and also a point for river ship- 

 ment. 



The outcrop appears to have the structure of a boss which has 

 cut through the country gneisses but has not shared in their extreme 

 metamorphism. The gneisses are Precambric and probably belong 

 to the earlier or basal division of the series represented in this 

 region. From the field associations the age of the granite intrusion 

 can only be indefinitely fixed, with a probability in favor of late 

 Precambric or early Paleozoic times. The proximity of the Cort- 

 landt series, which is only a few miles to the south, as well as the 



