156 



GREEN MOUNTAINS IN MASSACHUSETTS. 



north foot of Mount Prospect (Saddle mountain) where there is a well marked 

 southerly pitch. The westerly dips occur in one of the subordinate schist 

 masses, which forms a high cliff west of Cheshire reservoir, and again in a 



low knoll of schist at the extreme south limit 

 of the map, near Berkshire village, and in a 

 similar knoll south of Constitution hill and 

 west of Lanesboro. Besides these there is 

 one isolated observation between Lanesboro 

 and New Ashford, and two others on Ragged 

 mountain. So that the observations indicate 

 an almost universal easterly cleavage dip on 

 Greylock. 



The question may well lie asked how 



this can be. since the cleavage is so largely 



associated with the faulting of minute plica- 



-Diagrams showing the relation t ; 011s m s t ra ta which sometimes dip east and 



age to stratification at locality 55, 1 



Fig. 57.- 

 of slip cleavage i" stratification at locality ■" 



noigisiae of Monnt Williams, and 862, ridge sometimes west. The observations indicate 



mhiiIi m| Suua] lo;il. I leavaue parallel to axial 

 planes of plications. 



that where the sides of a fold dip in a direc- 

 tion opposite to that of the cleavage the axial planes of the small plications 

 are generally parallel to the cleavage planes, and 

 in extreme cases the faulted limbs of the plications 

 lie in those planes (see Fig. 50). Fig. 57 represents 

 this structure diagrammatically, asdrawn in the held. 

 Where the cleavage foliation and stratification foliar 

 tion both dip in the same direction, but at different 

 angles, the structure described in Figs. 56, 57 does 

 not occur, and the slip cleavage planes are then 

 either parallel with one or witli neither of the limbs 

 of the plications as in Fig. 59, or else there is a com- 

 bination of an extreme form of slip cleavage bor- „ „ ^. 



1 Fig. 58.— Diagram of part of north 



dering on slatv cleavage and of the coarse structure, s ; deof f° w »t l "' 1 -»- iocaiity32, west 



° J ° side of Deer hill, area 7X5 feel iho\i 



described in ( 'ase vi, Fig-. 48, and seen also in Fig-. 58, "'- coarae 'y pMoatea quartz laminae 



° ° traversing the schist; which has a 



in both of which the coarsely plicated quartz lamina' ' leava « c bordering on slaty cleavage, 

 are more or less independent of the cleavage foliation. Or, the cleavao-e 



