362 GEOLOGY OF OLD HAMPSHIRE COUNTY, MASS, 



the plateau alcove, just south of the mill jjond, is a series of roches 

 moutonnees, and au examination of these reveals a very interesting state of 

 things. 



The western well-smoothed ledge is at its north end a dark-green, 

 very fine-grained amphibollte, striking north and standing vertical, full of 

 wavy quartz veins and leases placed with the bedding. The whole is 

 little jointed, but a few feet along- the surface the traces of jointing increase 

 in distinctness, and farther south become slightly opened planes, and then 

 traces of motion of the fragments are seen, and infiltrated sand now indu- 

 rated in the joints. This disturbance increases slowly until all the frag- 

 ments are thrown into confusion, but one can see how they may be moved 

 back into their places. Three rods from the beginning the whole is a 

 breccia of large plates of the parent rock ; at 10 rods one begins to see 

 foreign pebbles — quartz and gneiss — and for a mile south the araphibolite 

 pebbles can be found in abundance. East of the amphibolite, which is 

 perhaps 10 rods wide, is a band of light-gray, fine-grained, thin- and 

 flat-laminated quartz-schist (whetstone), and still farther east is a second 

 adjoining bed of the fine-grained amphibolite. The first bed forms the 

 face of the bluft", and the water pours over it, and it can be examined 

 along the path up to the dam. All these show, southward, a full repeti- 

 tion of all that has been described for the first band, and the quartz-schist 

 is more abundant in the conglomerate and more characteristic of it than 

 any other rock. For the age and microscopic character of these rocks, 

 see page 196. 



The Bernardston (jneiss of the hill tvest of Montague. — On the northern 

 slope of this hill, near the house of H. H. Taylor (now burned), with its 

 center at the branching of the road at the most northerly loop of the 320- 

 foot contour on the map, is a large outcrop of a spotted, thin- and wavy- 

 bedded gneiss, with a greenish, greasy sheen of its mica, which shows 

 traces of pebbles and agrees with the South Vernon gneiss modification 

 of the Bernardston quartzite. It is a large outcrop, as the ice has planed 

 the conglomerate off" from the whole north face of the hill, and its similar 

 position to that of Mount Warner, in the Amherst basin, is interesting. 

 This was a great hill in the Trias, and furnished material in large amount 

 as the waters rose over it. To the north the Triassic rock grows rapidly 

 finer, but the long exposures in the bed of the stream at the foot of the 



