r86 NEW YORK STATE MUSEUM 



remaining exposures. Augen are less numerous and smaller and 

 often disappear. Much of the rock closely resembles gabbro 

 (nos. 6, 7, 10) being black and fine grained, yet in this phase 

 occasional augen are still forthcoming. Sometimes this basic 

 phase is present in considerable amount, but usually it is subor- 

 dinate to the green rock (nos. 7, 9) and the one passes into the 

 other with facility. Often they appear to be interbanded, but 

 this would be a natural result of the great metamorphism and 

 stretching which haye affected the rock, pulling out into bands 

 these somewhat more basic portions. 



Large crystals of platy, black hornblende haye deyeloped along 

 the cleavage planes in many places in these more basic rocks. 

 Occasionally accompanying secondary feldspars are also seen, 

 but ordinarily the hornblende is the only secondary mineral so 

 developed. 



Throughout the larger part of the section the green and the 

 black rocks appear in rude bands, which are not usually sharply 

 defined but grade into one another. It is impossible to resist 

 the impression that they are mere phases of the same rock, but 

 the repeated transitions are difficult of explanation. If the black 

 bands represent basic segregations from the magma, pulled out 

 into bands by the stretching incident on metamorphism, their 

 original number was very great. Yet no other explanation of 

 them suggests itself, and the evidence of stretching is impressive. 

 Locally fine grained, gabbroic rocks appear which show sharp 

 boundaries against the syenite and clearly represent later dikes. 

 Ko case was noted in which such dikes cut the black phase of the 

 syenite, and the writer is still in a state of some perplexity as to 

 the actual conditions, though inclining to the view that most of 

 the black rock is merely a phase of the syenite, in spite of the fact 

 that dikes of a later gabbro are present. This gabbro, moreover, 

 is clearly a closely related rock. 



All the rock through the major portion of the section is finer 

 grained and more gneissoid than the rock at the village, with 

 feldspar augen sparingly present, instead of abundant. The 



