HOOSAC MOUNTAIN. 91 



strikes north 85° east, dip 50 northerly, gradually turning on both sides 

 of the cove to a north and south strike. Thus on the east side of the rove 

 it strikes north 65° east and dips west; approaching the succeeding point 

 of the mountain it strikes north and south, then at the extreme of this point 

 north 37° west, dip vertical. The extreme point is formed by a very massive 

 vitreous quartzite, 150 yards north of which there is a loose outcrop of lime- 

 stone, probably not in place. There are also small ledges of schist on the 

 west edge of the cove which probably are in place; strike north 32° east, 

 dip west steep. They show that the schist area- north of the cove runs in 

 here near the quartzite. As we go east from this second point the quartzite 

 strikes north 30° west, dip northeast, then begins to strike east and west 

 and dip northerly with a constant strike. About a mile from this second 

 "point," or sharp canoe, in the quartzite, we come to a very important local- 

 ity, where this massive quartzite and conglomerate passes along the strike 

 into the white gneiss series of Hoosac mountain. Half a mile from the 

 second "point" the massive quartzite runs up the hill, striking north 80° 

 east, dip northerly 30°. A great thickness of massive quartzite is exposed 

 here; in some cases there arc beds of well-marked conglomerate with quartz 

 pebbles; this quartzite runs in great cliffs up the side of the mountain (see 

 map, PI. i). As it approaches the summit it becomes more and more 

 micaceous. At the summit and near the north to south road running to 

 Windsor, it changes along the strike within "200 feet into a fine-grained white 

 gneiss. The quartzite on this hill is separated into two divisions by a layer 

 of black biotite schist of some thickness The rocks turn around this hill, 

 which represents a quartzite dome (the rocks dipping north), and then by 

 their dip are carried down to Dry brook, to which they can be easily traced 

 by long cliffs and scattering outcrops. 



This brings us to the area between Dry brook on the south, the "point 

 of the mountain" north (where the central series of Hoosac mountain 

 makes its sharp turn to the east), and the western border of the Hoosac 

 schists on the east. The rocks we hud in this area are varieties of the 

 white gneiss, often coarse. Along the western border there are quartzites 

 and conglomerates interbanded with gneisses, while the large area of schist 

 in lloosic valley extends east into the gneiss area. Three general pecu- 

 liarities of structure may be noted (see map, PI. i): 



