a Garnetiferous gneiss 



b Crystalline limestone 



c Quartz-mesh limestone . 



d Undivided gneisses ; includes minor amounts of limestone, actmolitt 

 schist, etc., but mostly pyritoiis and allied gneisses 



e Small masses of undivided gneisses inclosed (in the amphibolite) or mter- 

 bedded (in the garnetiferous gneiss) 



Fig. 21. Formations of the sigmoid flexure; scale, about 3 inches 



/ Gabbro-amphibolite, intrusive in the garnet gneiss, and cut by latei 

 granite gneiss 



g In the garnet gneiss, amphibolite sills and similar smaller bodies formuij 

 a coarse-textured injection gneiss. In the granite area, lenticular and elon 

 gated amphibolite xenoliths, often intimately injected with granite 



h Granite gneiss, in relatively distinct areas 



I mile. Southeast corner of Canton quadr 



i Granite gneiss, forming relatively small sheets and lenticular bodies i 

 mately injecting the amphibolite and garnet .gneiss, often producin 

 mix- rack 



;■ Unusually large masses of pegmatite 



/,• Potsdam sandstone and conglomerate 



/ Precambrian undivided and inferred; usually covered by heavy tdl 



