74 GEOLOGY OF OLD HAMPSHIEE COUNTY, MASS. 



bridge in Becket the gray, gametiferous, feldspathic mica-schist sets in and 

 continues to the sawmill, where the Becket gneiss appears in a large quarry. 

 Still farther south, in the west corner of Blandford, the Rowe schist nan-ows 

 and occupies only the width of the North Meadow Pond, but is still a well- 

 defined band of seric"ite-schist, while the Hoosac schist retains its width and 

 appears in the high hills west of North Blandford. 



Two miles farther south, at Blair Pond, the rock from the Becket gneiss 

 below to the liornblende-serjjentine band above, and including thus both the 

 Hoosac and Rowe schists, is a rather coarse mica-schist, not sericitic, but 

 quite feldspathic, and in })laces abounding in staurolite crystals. The 

 country begins in this latitude to abound in granite stocks and swarms of 

 dikes, and the feldspathic character of the schists seems to depend largely 

 on an impregnation from this granite, and the feldspathic constituent is 

 arranged in flat blotches on the foliation faces, rather than in aliundant small 

 porj)hyritic crystals, as is the case farther north. The lithological dis- 

 tinctness of the Hoosac schists and the Rowe schists disappears, from the 

 loss of the hydrated mica in the upper bed and of the porphyritic albite 

 in the lower, and I have not tried to separate the two beds in the Granville 

 quadrangle. 



By the development of three anticlines in these schists, in the two outer 

 of which the Becket gneiss comes to the surface, and by the troughing out 

 of the hornblende-schists in the intervening synclines, this complex expands 

 eastwardly to cover the whole of the Granville quadrangle, Avrapping aroimd 

 the separate area of gneiss in East Granville and Granby. (See map, PI. 

 XXXIV.) 



Granite continues abiindant, and the rock becomes in the whole south- 

 ern portion of the Granville quadrangle a very coarse muscovite-biotite- 

 schist, showing on foliation faces continuous films of large muscovite plates, 

 or muscovite and biotite regularly intergrown, Avith, at times, feldspar or 

 pegmatitic quartz-feldspar masses in the interstices, in place of the usual 

 granular quartz. Toward the base of this complex on its western border, 

 and in better development around the Granville gneiss, is a rock of very 

 attractive appearance. It is a white, gneissoid rock of rather coarse grain. 

 In the limpid, granular quartz mass the rather distant scales of silvery musco- 

 vite, pale-red biotite, and pyrite are compressed into perfect parallelism, so 

 that on foliation faces a very bright, silvery luster occurs. Considerable well- 



