26 NfiW YORK STATE MUSEUM 



absent, and in some cases hypersthene and monoclinic pyi*oxene 

 occur. 



In many places the granite varies to quartz monzonite, and 

 locally it becomes true quartz diorite as, for example, by the road 

 three-fourths of a mile north of the mouth of Ferguson brook (see 

 no. 26 of the accompanying table of thin sections). 



Narrow bands of pegmatite and silexite parallel to the foliation 

 and without sharp contacts were observed in many portions of the 

 granite areas. Also there are occasional larger pegmatites in the 

 form of dikes usually with better defined boundaries, some parallel 

 to the granite foliation and some cutting across it. 



Many local portions of the granite contain small inclusions, 

 lenses, or mere shreds of amphibolite (presumably metagabbro), 

 and less commonly bits of Grenville rocks. 



The nature of the variations from the great general body of 

 typical, medium-grained, moderately foliated, pink granite may be 

 satisfactorily brought out by describing certain selected portions of 

 the granite areas. On a large scale perhaps the most interesting 

 place to observe variations is the body of rock constituting Bald- 

 head and Moose mountains and vicinity. Most of this rock is 

 medium to moderately fine grained, but locally distinctly finer and 

 coarser grained facies come in, these latter not being at all sharply 

 separated from the main mass. Such variations are in zones or 

 bands from a few feet to some rods in width. Very locally these 

 are also aplitic and pegmatitic facies. The rock is never highly 

 foliated, but this structure varies notably. Such variations in com- 

 position, granularity, and foliation are all practically parallel to the 

 general foliation with no evidence that one facies really cuts 

 another. 



The hill just northwest of Luzerne consists of light brown to gray 

 hornblende granite varying to quartz monzonite and grano-syenite. 

 It is mostly medium grained with local coarse-grained variations 

 and distinctly foliated, but in some places only slightly so. Very 

 locally the foliation is highly wavy. No. 12 of the table of thin 

 sections shows the minerals contained in a typical specimen. 



In the abandoned stone quarry near the railroad 3 miles south of 

 Stony Creek station the well-foliated, medium-grained granite 

 varies distinctly to grano-syenite, and in color from pink to gray. 

 It is cut by many narrow bands of only moderately coarse pegmatite 

 parallel to the foliation, and some coarse-grained pegmatites cut 

 across the foliation. As shown by no. 20 of the table, this granite 

 is notably monzonitic. 



