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NEW YORK STATE MUSEUM 



resemblance to other garnet gneisses of admittedly sedimentary 

 origin, and the inclosure of a thick strip of apparently sedimentary 

 garnet gneiss near the west border of the granite, are facts which 

 are in favor of regarding the rock in question as fragments of a 

 sedimentary series, which owe their present position adjacent to 

 and within the granite, to purely accidental circumstances of a 

 tectonic nature. 



There are other garnet-bearing rocks, however, having a marginal 

 distribution with respect to the granite, which appear to be more 

 closely related genetically to its intrusion. These are not strictly 

 garnet gneiss in the same sense in which this term is herein used 

 to designate those feldspathic garnet-bearing rocks whose general 

 field relations indicate them to be regionally metamorphosed Gren- 

 ville sediments ; rather are they garnetiferous amphibolite contact 

 schists which must be regarded as transitional between the Gren- 

 ville limestones or calcareous schists and the black amphibolite 

 which is invariably interposed between them and the acid intrusive. 



The three localities to be mentioned as best affording illustration 

 of this genetic relationship are: (i) the south border of the belt of 

 amphibolite bordering the granite northwest and east of Eddy; 

 (2) the lower contact of the Canton belt of granite gneiss, as ex- 

 posed in a 20-foot ledge on the left bank of the Grass river, one 

 and one-tenth miles northeast of the Pyrites railroad bridge near a 

 rapids locally known as Woodcock's rapids; (3) part of the north 

 border of the granite mass southwest of Pyrites, on the west edge 

 of a small knoll lying one-quarter of a mile southwest of the road 

 which cuts the eastern extremity of the granite. 



ssw 



NNE 

 20 ft. 





Fig. 3 Cross-section of upper granite contact, (a) Pink granite gneiss; 

 (&) garnetiferous amphibolite passing upward gradually into; (c) thin- 

 bedded limestone. Contact between (a) and (b) not exposed. This is taken 

 as an example of contact alteration of limestone to (garnetiferous) amphi- 

 bolite. Limestone about 10 feet thick. 



About eight-tenths of a mile south-southwest of upper Pyrites bridge. 



