GREEN MOUNTAINS IN MASSACHUSETTS. 



43 



larity again conies in, causing a more ridge-like topography, until the deep 

 east to west valley of Dalton, a mile or so south of the map (PL i), bounds 

 the region on the south. 



On the east the mountain joins the hilly country extending to the 

 Connecticut river; on the west the brOad Hoosic valley, running- north and 

 south, bounds Hoosic mountain ami separates it from the mass of Greylock 

 mountain, the highest in the state. (See Fig. 9). 



The relations of topography to geological structure are often notice- 

 able. The whole eastern border of the area shown on the map is covered 



Fig. 10. — Profile of part of west crest of Hoosac mountain, looking east from Hoosic valley opposite Adams. 



This shows the continued DOrtherly pitch of the axissome miles south of point shown in PI. xi, B. The summit in the 

 right center ia of white gneiss (Vermont formation) with a little indistinct minor ridge of the Hoosac schist trough, both 

 slanting to the left (north). 



by the schists, characterized by a uniform north to south strike and steep 

 easterly dip of their structural planes; and the ridge topography, with deep 

 cross-gorges for the streams, ; s evidently due to that structure. 



The long crest of Hoosac mountain, forming the main watershed, 

 coincides in direction and position with the axis of the northerly pitching 

 fold which forms the principal feature of the mountain, and with the axis 

 of the central core of granitoid gneiss. The presence of the limestone in 



