50 NEW YORK STATE MUSEUM 



south and east sides by limestone which dips on an average at a low 

 angle toward the west. The east margin of the schist also rests at 

 a low angle. The north border of the latter, however, as is partic- 

 ularly well shown in the grove east of the road, is upturned and 

 even overturned sharply, with the result that the schist, which is 

 perhaps not over 15 feet thick at this locality, forms an asymmet- 

 rical syncline whose axial plane dips some 30 or 40 degrees north- 

 westward. West of the road the fold becomes tighter, almost iso- 

 clinal, and the axial plane dips northward at a ver>- steep angle. 

 The sketch (figure 7) is designed to show, somewhat diasrammati- 



FiG. 7 Outij-ing as>-mmetrical syncline of thin-bedded quartzite and quartz 

 schist, overh-ing crystalline limestone. Structure of associated limestone 

 entirely h>-pothetical. Length of section, one-fourth of a mile, (a) Lime- 

 stone; (6) quartzose formation. Pitches southwest slightly. 



Three and one-tenth miles south by east from Canton, one-half mile east 

 of Grass river, 



cally, the structural relations at these points. It is evident that the 

 knoll borders an area of not \ery intense deformation on the south 

 (see plate 8, lower figure) and one of greater complexity on the 

 north. This feature of practical quiescence in the limestone 

 immediately adjacent on the south side is unaccountable, par- 

 ticidarly as it is adjoined by areas of intense tectonic activit>% the 

 northerly of which is indicated by the nearly isoclinal structure 

 developed at the edge of this outlier of quartz schist. 



AMPHIBOLITE 

 The amphibolites constitute the only remaining formation which 

 needs to be considered here. From the point of view of origin, the 

 majority' of these dark, plagioclase-hornblende rocks present greater 

 difficulties than any of the other types met with. The reason is not 

 hard to find. It has been repeatedly observed in late years that 

 amphibolites are an end-product which may arise in any one of 



