178 



GREEN MOUNTAINS IN MASSACHUSETTS. 



folds licet mic sharper again and more compressed, and the schist area 

 rapidly narrows (Sections N and 0), and the structure continues much com- 

 pressed to the extremity of the 

 mass. On either side of these 

 two main svnclines the subordi- 

 nate folds are more or less open, 

 and have their axial planes ver- 

 tical or else inclined east or west. 

 The continuity of the folds and 

 their mutual relations are shown 

 in Fig. 12. Longitudinal sec- 

 tions along the two main syncli- 

 nal axes ( P and Q) show that the 

 trough bottom deepens at two 

 points. In the eastern syncline 

 H (P) the deeper part of the north- 

 ern trough is shown to be about 

 under the center of Ragged 

 mountain, while in the central 

 one (Q) it is about 2 miles far- 

 ther south between (Ireylock 

 and Saddle Ball (Section I); 

 and this also would seem to be 

 the deepest part of the entire 

 synclinorinm. The northern 

 edge of both of these troughs is 

 at the extreme north end of the 

 Greylock mass, and their south- 

 ern edge l.\ to Si miles distant, 

 near Round rocks and the south- 

 east spur of Saddle Ball. South- 

 of these main troughs are two 

 shallower parallel ones, the centers of which lie west of Cheshire reservoir 

 (P, Q). To the west of these two long axes the mountain mass is made up of 



tz^^^r 



Fig, 72.— Diagram si 



! In I ', n ylnrk -\ ni'limir 

 Tls- XVIII XXII. 



Dg the i 

 Redr, 



ity of the main folds 

 imi the large sectioi 



