24 NEW YORK STATE MUSEUM 



GARXET GXEI5S 



For purposes of description it is convenient to separate the garnet 

 gneiss into three areal divisions : first, that which forms the greater 

 part of the large S-shaped fold found in the southeast comer of the 

 quadrangle, and which is by far the largest mass of the formation on 

 the Canton sheet; second, the long, narrow bands of gametiferous 

 rock which are characteristically associated with the periphery of 

 areas of granite gneiss; third, all other occurrences, found inde- 

 pendently of the first two tv'pes and interbedded with typical Gren- 

 ville sediments, such as limestone, rusty gneiss, quartz schist and 

 others. These three divisions offer in the inverse order of that 

 given, relationships more and more obscure, and problems in genesis 

 of greater and greater difficulty. 



The garnet gneisses of the third class are found in thin beds, 

 accompanied by other rocks concerning whose sedimentar}^ origin 

 there can be little doubt ; thin layers of crystalline limestone, rusty- 

 weathering gneiss, quartz schist and siliceous paragneisses of vari- 

 able composition make up their normal association. Their chief, and 

 indeed their only development is in the area lying between Little 

 River hamlet and Xorth Russell, and included between the western 

 edge of the sigmoid belt and the granite boss east of Pyrites. Within 

 this area the strata of garnet gneiss form detached and fragmentary 

 masses concerning whose mutual stratigraphic relationships it is im- 

 possible to make definite assertions. It is evident that if ever they 

 were continuous, their close association with a rather large area of 

 limestone during periods of disturbance has made their disruption 

 all the more easy and complete. 



The most important area of this kind is that lying northwest of 

 and close to Xorth Russell, where the outcrops are found fringing 

 the border of a fan-shaped deposit of glacial boulder till. The 

 ledges strike as a rule toward the northwest, directly contrar}- to the 

 regional trend of formations, which is northeast. Where any sig- 

 nificant structure is observed, as in the two outcrops immediately 

 west of the fork in the road rtmning north out of Xorth Russell, it 

 is a northwestward pitch affecting the axes of minor crumplings. 

 This feature indeed is normal for the southeast half of the Pre- 

 cambrian area mapped, though the broader relations of this mass 

 of garnet gneiss to the Grenville rock adjoining it on the northwest, 

 and to the sigmoidal structure to the east, are uncertain. From the 

 fact that its trend is northwestward, and in this respect parallel to 



