BERFARDSTON SERIES OF UPPER DEVONIAN. 283 



of Grass Hill, and is apparently coutiiiuous under the sands with the larger 

 area west of the railroad. It dips under the hornblende rock to the east. 



It is everywhei'e a fiue-graiued, light-gray, fissile quartzite, with small, 

 fresh feldspar crystals porphyritically disseminated in it, often quite abun- 

 dantly. These reach 1-2""™ in cross-section, and are often, but not always, 

 striated. The}" are much larger than the quartz grains, and often have sharp 

 crystalline outlines. (See " Petrographical description," Nos. 6 and 7, pp. 

 288-289.) 



In the area south of the great fault at the Purple blind road, and far west 

 from this area, the rock is marked by an abundance of grains of lavender 

 quartz included in it, which appear to have come from the pre-Cambrian 

 gneiss of the Green Mountains, as I have found it characteristic of the 

 Washing-ton gneiss in western Massachusetts. Muscoxdte, so abundant in 

 the lower quartzite, is wholly wanting; rarely a small amount of biotite in 

 fine scales, or, at one outcrop, of hornblende in scattered needles, appears. 



The dips of the rocks and of the slates below are so low, and, with the 

 strikes, vary so rapidly and irregularly within narrow limits, that I am left 

 in slight doubt as to the exact conformity of the two for any long distance. 

 Along the line of junction for 2 miles north or south from the northern 

 road over the range no contact of the two could be found, but in the 

 whole distance they seem to be exactly conformable and to have shared all 

 minor disturbances; for instance, although the rocks are tilted so that they 

 strike N. 65° E. and dip 40° SE., they have also been subjected to an east- 

 west thrust, as is seen on a large scale farther south, so that small portions 

 placed irregularly among the rest have a north-south strike, which is shared 

 by both the schists and the quartzite. 



The basal conglomerate, often blackened by argillitic niaterial, is a 

 rock of very different habit from this fine-grained, biotitic, feldspathic quartz- 

 ite; but the description above given of the passage of the beds across Ver- 

 non indicates that the former passes into the latter eastward beneath the 

 schists, and is then brought up by a fault along the eastern base of the 

 schist series and in places thrust over the latter in apparent conformity. 

 The fault line must be an exceedingly tortuous one, and the Mount Her- 

 mon series, on the east of this line, must be a repetition of the West North- 

 field series. The former series stretches from Otter Pond Brook, in Gill, to 

 Mount Hermon, and contains the same succession of mica-schists and 



