194 



GREEN MOUNTAINS IN MASSACHUSETTS. 



character of the calcareous belt, and its general trend, erosion proceeded 

 quite as rapidly laterally, north and south, along the strike as easterly across it. 

 The deep incisions south of the Bald mountain spur (Groodell brook, 

 Mitchell brook, etc.) and the corresponding ravines on the east slope of the 

 range ( Peck's brook, Bassett's brook, etc.) are the usual effects of the drain- 

 age of a mountain range; and the alternation of precipice and gentle declivity 

 in these ravines is explained bv differences in the character of the noncal- 

 careoUs schists themselves, and also by the alternation of calcareous and 



Fin. 74.— Outline sketch of Round rocks and the northern slope of Saddle Ball and Sugarloaf mountain from th • 

 west, locality 772 on East mountain, showing the hollow between Round rocks and Saddle Ball due to the erosion of the 



calear 9 schist (Bellowspipe limestone) i also Ihe cliff at Round rocks in the Berkshire schist, and the upper bench on 



Saddle Ball in the Rreylock schist. 



noncalcareous schists. Some of these ravines are quite as steep and diffi- 

 cult ol' access as any in the Hopper. 



The problematic upper bench on Saddle Ball (see PI. xm, Fig. 74 and 

 Section K) is possibly due in part to the horizontal position of the strata 

 along a portion of the slope, and possibly in part also to pre-glacial erosion. 

 These benches and those on the long southeast spur of the same mountain 

 may also be connected with the gentle northerly pitch of the south end of 

 the ureat troughs. They require further study. 



The saddle between (Irevlock summit and Saddle Ball seen for a great 



