GEOLOGY OF THE NORTH CREEK QUADRANGLE 



17 



TABLE I 

 Pyroxene syenite 





















41 



















0) 





u 



<u 





0) 





.^2 



4; 

















•2 







Plagiocla: 





c 





c >> 



■!-> 















03 



6 





 



a> 

 C. 







Ih 







a 











 c 

 











c 

 

 



>. 



Oh 



+-• 



c 



H 













01-Lab 























I 



17 



25 







55 

 01 



12 





5 



25 



? 



1 



2 



1 



1 



























2 



^3 



15 



25 



15 



14 



01 



t8 



I 





10 



T 



1 

 2 



1 



i 



























3 



14 



25 



25 





5 



20 



8 





15 



I 



1 

 2 



1 

 4 



1 



4 



little 















Granitic hornbl 



ende 



syenite 



















01 



















4 



15 



25 



25 





6 

 01 



22 



18 



2 





I 



1 

 2 



1 

 4 



1 

 4 



5 



34 



5 



50 





5 

 01 



24 



12 







2 



I 



1 

 4 



1 

 4 







6 



12 



10 



35 



2 



12 

 01 



25 



14 







I 



1 

 2 



little 



§ 









7 



16 



5 



65 





3 



25 



1 

 2 



1 

 2 





1 

 2 



1 

 2 





littlo 



The color of the fresh rock is the usual greenish gray of the 

 Adirondack syenites, while the weathered surfaces are of yellowish 

 brown to brown color. Because of vigorous glaciation even the 

 weathered surfaces are hard, decomposed rock seldom being seen 

 except in a few protected places on the south sides of mountains. 

 Below this weathered surface it is usually not more than a few 

 inches to the fresh greenish gray rock. 



That the syenite has been intruded into the Grenville is abund- 

 antly proved by the many inclusions of all sorts of Grenville rocks, 

 but most of these are too small to be represented on the geologic 

 map. Some of the best examples of Grenville inclusions are to be 

 found in the mixed gneiss areas which will be described below. 



Pyroxene syenite. This syenite represents the most basic facies 

 of the great syenite-granite intrusive mass. The generally faint 

 development of gneissoid structure, low quartz and hornblende con- 

 tents, and the presence of pyroxene are the chief differences be- 

 tween this and the granitic hornblende syenite. The range in com- 

 position is well brought out in table i which represents thin sections 

 of carefully selected samples. The pyroxene is seen to be the 

 most characteristic mineral of the rock. This pyroxene is of a 

 beautiful green color, clearly monoclinic, and shows good cleavages. 



