272 GEOLOGY OF OLD HAMPSHIRE COUNTY, MASS. 



DESCRIPTION OF THE RAXGE FROM BERXARDSTOX TO SOUTH 



VERNOX. 



Directly opposite the Williams farm aud 200 rods distant, on the 

 east side of Fall River, begins a range of low kills wliicli rnn northeast 

 between the two towns named above. This range of hills is backed on the 

 northwest by a much higher range of argillite hills — Bald Mountain and 

 Pond Mountain — and is bounded on the southeast by the high terrace sands, 

 tlu-ougli which one large area and many smaller islands of the rocks of the 

 Bernardstou series emerge. I have called this the West Northfield range, 

 from the town in which it for the most pai-t lies. The road running along 

 the east side of Fall Eiver skirts the range at its western end, and the main 

 road from Bernardstou to South Vernon borders it on the south and east, 

 while the roads which branch from the latter and cross the range are named 

 from some resident upon each, as given in Beers's atlas and as marked on 

 the map, PI. IV. 



The mapping of this area was difficult, both because the rocks are 

 thrown into great confusion, many beds being in places echeloned so that 

 the local strike regularly disagrees with the general run of the bands, and 

 because of the presence of several large drumlins which effectually conceal 

 the underlying rock. The intervening areas are, however, so enthely free 

 from drift up to the very foot of these hills that, were it not heavily wooded, 

 the region would furnish abundant outcrops, and, as it is, the frag-ments on 

 the surface can be safelj^ used to determine the rock below. The series 

 wraps around the argillite and uniformly dips away from it, generally at 

 low angles, at first south, and then for a long distance southeast; then it 

 swings sharply round, crossing the State line with dips a little east of north, 

 making thus a great bend to the westward as it crosses the town of Vernon. 

 I have not been able to prove the existence of folds or overturns, and the 

 present position of the beds seems to be best explained as the result of very 

 extensive faulting. 



The argillite. — I have assigned to the argillite the broad area marked 

 "Coos" upon Professor Hitchcock's map (17, Atlas), to wliich he also assigns 

 the slates of the Bernardstou series, because I have found that the boundary 

 between it and the argillite to the west as given upon that map has no 

 justification in any physical change in the character of the rock where it is 

 di-awn, and the argillite can be traced unchanged up to and dipping beneath 



