58 



NEW YORK STATE MUSEUM 



ate vicinity are younger or older than the gabbro-diorite dikes but, 

 since the aplites are more strictly parallel to the foliation of the 

 granite and not so sharply separated from it, it is probable that 

 they are the older. Since the granite is only moderately foliated 

 and the aplite not at all, it seems evident that the foliation of the 

 gabbro-diorite dikes, especially near the borders, is the result of 

 magmatic flowage rather than of regional pressure. 



At the top of the ridge one-half of a mile northeast of the summit 

 of Catamount mountain, there are three more of the gabbro-diorite 

 dikes. The middle one is fully 40 feet wide and distinctly gneis- 

 soid. All three strike about N 20° E. A diabase dike 3^^ feet 

 wide, and a pegmatite dike 3 feet wide, each cuts obliquely across 

 the largest of the gabbro-diorite dikes. 



On the mountain i^ miles north-northwest of East Kilns, two 

 more gabbro-diorite dikes, presumably of the same age as those 

 above described, show good contacts against the coarse granite. 

 Each dike is about one-third of a mile long. The larger one is 

 fully 100 yards wide, and the other is much narrower, being 

 reduced to a width of only i foot at the western end where it 

 very sharply cuts the granite. Fresh rock from the larger dike is 

 dark greenish gray, and it weathers to a brownish gray. It is fine 

 to medium grained and moderately gneissoid. It looks very much 

 like a very basic facies of syenite, but its high content of albite 

 and pyroxene (see no. 58 of table 4) makes it distinctly different. 

 It differs from the Catamount gabbro-diorite by its high percentage 

 of monoclinic pyroxene. 



Table 4. Thin sections of gabbro-diorite 







0) 





























■^ 







CD 







V 

















J3 



<a 



« 



• i! 









•^ 















Uh 







^ b 







.fi 



























+j 















c 

 55 



c 



V 



a 

 





 



u 

 







"o P. 

 



c 

 



"(3 



5 





>> 



J3 

 C 

 u 











s 



'c 



D 



S 



P. 



<; 



c 

 



•^f> 



IS g 5 a 



so 





Ol.-An. 25 









10 



12 



I 



I* 



i 



little 



so 



15 g 5 b 





t8 



Alb. 32 









24 



20 



4 



ij 



h 





57 



IS g 4 



18 



18 



Alb. 17 





X 



3 



40 





I 



2 



1 





S8 



17 k 2 





10 



Alb. so 



28 



6 





2 



I 



2 



ij 



i 





Nos. 56, 59 and 57, from the top of Catamount mountain; no. 58, from 

 top of mountain i^ miles north-northwest of East Kilns. 



