MOUNT GREY LOCK. 



195 



distance south (I'l. xv) is due to the synclinal structure of the central ridge, 

 the westerly dip on the cast side of Greylock, the easterly dip on the west 

 side of Saddle Ball. The saddle in the central crest as seen from Mount 

 Equinox, i. e., the north northwest, is due to the pitch of the sides of the 

 central trough. (See Fig. 30 and Section ().) The northeast to southwest 

 trend of the ridge between the two summits and the northerly trend of the 

 central ridge north of Greylock correspond to changes in the direction of 

 the strike, but the general trend of East mountain does not conform to the 

 strike of its strata. 



The two depressions, alternating with three elevations, seen on the range 



JMtPrvspect BaZdMt ^>ur 



■Sculd/s- Bali '■ 



Hound- Hucis 



Fig. 75.— Sketch of the Greylock mass from the southwest (locality 1008, on north Potter mountain) showing tin- surface 

 of tin- Bald mountain spur and of Round rocks pitching toward each other owing to tin' ]iit<-li of the synclinorial axis. 



from Clarksburg mountain and the Stamford valley are due to the presence 

 of the two belts of the upper limestone and calcareous schist on either side 

 of the central ridge (Berkshire schist) one forming the Notch, the other 

 "Wilburs pasture," and the north to south part of the Hopper. 



The gentle northerly slope of the surface from Round rocks to Jones's 

 Nose (see Pig. 74, and Section Q), and the similar southerly slope of the 

 top of the Bald mountain spur, as seen from North Potter mountain on the 

 southwest (Fig. 75), are probably due to the trough structure of the entire 

 mass, the former constituting a part of the northern trough of the great cen- 

 tral syncline. To this structure are probably also due the long, steep south- 



