20 NEW YORK STATE MUSEUM 



the presence of an occasional low dip in separate instances, such as 

 would be expected on the limb of a flexure of gentle character, 1)e- 

 sides a minor amount of more intense crumpling controlled by axes 

 pitching slightly (not over lo degrees usually) toward the south- 

 west. Though definite synclines can not be satisfactorily demon- 

 strated in the field, their presence is strongly suggested by the zig- 

 zag character of the terminal boundaries of the areas in an attempt 

 to correlate the individual outcrops. The two patches are appar- 

 ently strata of indeterminable thickness, probably not over 50 feet, 

 associated with and grading into micaceous and garnetiferous 

 schists, above and below. Their mutual stratigraphic relations are 

 unknown, but the southeast area, characterized by a predominance 

 of light-colored silicates, not abundant in its neighbor, would seem 

 to be a distinct horizon from the other. 



The one remaining limestone area to be mentioned as illustrating 

 the abruptness with which a stratum may be terminated by mechan- 

 ical deformation, is that forming the core of one flexure of a pitch- 

 ing sigmoidal isocline in the southeastern corner of the sheet. The 

 rock at this point, except for that occurring in the middle of the belt 

 and described elsevvhere in this bulletin (see pages 22, 23, 49), is of 

 the usual coarse-textured crystalline type. It forms the floor of a 

 small ampitheater opening southwestward, the walls of which are 

 a continuous folded belt of thick garnetiferous gneiss. This i^elt, 

 by turning in a semicircular course and doubling back upon itself, 

 suddenly obstructs and cuts out the limestone at its northeastern end 

 in the direction of the normal trend of formation. 



In a number of cases the rock which has been referred to broadlv 

 as limestone is very impure. The character of the formation varies 

 greatly ; while always wholly crystalline it shows transitions to types 

 consisting largely of the silicates, feldspar, mica and pyroxene. 

 Impurities are sometimes found disseminated through the general 

 rock mass, but most frequently they are segregated in thin bands 

 and streaks. 



Among the localities illustrating this variation in composition, and 

 accessible to easy obsen^ation, may be mentioned the old abandoned 

 Stevens quarry, and the Crary Mills quarry. The former is situ- 

 ated one and four-tenths miles northeast of the Pyrites railroad 

 bridge, near the bottom of the south slope of the 440 foot knoll on 

 the left bank of the Grass river. The rock is a medium-grained 

 marble, white or grayish white in color, slightly banded, and singu- 



