214 GEOLOGY OF OLD HAMPSHIRE COUNTY, MASS, 



dip 10°-15° Yj.\ and as one goes east from the boundary down tlie steep hill 

 and across the quartzite the dip of this Latter rock increases g-radually to 

 45°, showing that the quartzite mantles over the gneiss. The quartzite (h) 

 is here quite micaceous, the mica being, as usual, a shining-white rauscovite, 

 or often a sericite. In places coarse patches of biotite scales also occur. 

 Southward along the crest of the hill this bed is in one place distinctly 

 conglomeratic, pebbles of quartz about an inch across and much flattened 

 by the compression of the rocks, making up the mass of the rock in a great 

 vertical cliff looking west. West of C. T. Swan's, where the 1,200-foot con- 

 tour crosses the road, 200 rods south of the Robbins house, on the mountain 

 crest, it is a very vitreous quartzite, resembling an aggregation of the quartz 

 nodules in common mica-schist. Some beds here also abound in a shining- 

 white mica, and others carry a little biotite. The thickness opposite C. T. 

 Swan's house is 575 feet. This is followed by a very coarse, w^avy, very 

 micaceous, often sericitic, garnet-bearing schist of white color (c). It is 

 40 feet thick on the Robbins road; in the section ojjposite C. T. Swan's 

 house, 65 feet, (h) and (c) are the equivalents of the Rowe schist. 



The amphibolite (r/), or the Chester amphibolite, is a greenish-black 

 rock of fine grain, separating into thin plates which have a ligniform struc- 

 ture from the perfect "stretching" of the rock. It is usually of even grain 

 and free from all accessories. Nodules of albite and ilmenite occur rarely. 

 It is, on the Robbins section, about 500 feet thick; on the Swan section, 

 330 feet. 



The whetstone-schist (e), or the Savoy schist, is a gray, arenaceous 

 biotite-schist or micaceous quai'tzite. The biotite is in thin scales, not 

 concentrated upon foliation planes, but scattered sparingly and evenly 

 through the rock. Near the top, at R. H. Minot's house, is a very rusty 

 laver full of coarse garnet and hornblende. In the Swan section its thick- 

 ness is Gl'2 feet. 



Then follows a coarse muscovite-schist (/), often very micaceous. It 

 is affected by both a fine corrugation of the foliation sm-faces and a general 

 twisting and contortion of the folia themselves. It is graphitic and abounds 

 in garnets and staurolite, the latter especially abundant toward the base. 

 Its thickness in the Swan section is 354 feet, but here the whole thickness 

 is not present because of the fault; a little farther south, opposite the 

 schoolhouse, it is 445 feet. This is identical with the Conway schist. 



