QUARRY MATERIALS OF NEW YORK 85 



noted within the section traversed. On the eastern border between 

 milestones 62 and 64 the granite becomes finer in texture, evidently 

 the result of granulation superinduced by pressure metamorphism, 

 but maintains its normal composition and for the most part its 

 massive habit. 



With the exception of the two large bodies of gneiss that prob- 

 ably represent included masses of the older Grenville rocks, the 

 area where traversed is quite bare of inclusions or contrasting ma- 

 terial of all kinds. The most common variations are produced by 

 segregated stringers of quartz and pegmatite, but these have a very 

 limited development. In general, the granite shows much uniform- 

 ity, the changes of texture or appearance taking place very gradu- 

 ally. 



The ledges are intersected usually by widely spaced joints, of 

 which the vertical ones are in two series crossing at high angles 

 so as to produce heavy blocks. Dimension stone of any commercial 

 size could be obtained in most of the ledges. 



The extent of the outcrop along the railroad, the only part where 

 a complete traverse has been made, indicates that the granite covers 

 a very large area. It extends no doubt for considerable distances 

 to the north and south. Exposures of red, somewhat gneissoid 

 granite of similar character have been noted by the writer in the 

 northern part of Fine township and in the Cranberry lake region. 

 Smyth mentions the occurrence of red hornblende gneiss in northern 

 Lewis county which he states shows massive phases at many places 

 and resembles as a whole a slightly modified hornblende granite. 

 This may represent the southern continuation of the area under 

 consideration; at any rate it may belong to a common magmatic 

 source. 



Microscopic examination. A study of thin sections from sam- 

 ples taken at different places within the area shows the rock to 

 belong to the hornblende-biotite granites, with the two dark min- 

 erals in about equal proportions or with the hornblende pre- 

 dominant. They are, however, of subordinate importance to the 

 feldspars and quartz, and in composition the stone ranks with the 

 acid class in which the silica amounts to 70 per cent or more, as 

 is confirmed by the results of chemical analyses. The feldspar in- 

 gredients include microperthite and microcline which lend the red- 

 dish color to the mass and a variable but minor quantity of plagio- 

 clase, mostly oligoclase. Quartz is plentiful. In the more massive 



