262 J. D. Dana on the Quartzite, Limestone, etc., 
ne. 
Devany’s Bluff has been stated to be the front of the plateau 
on which the south end of Bear Mountain stands. Going east- 
ward a mile and a half, and then rising by a rough and steep 
road to the top of this plateau, the dip of the upper gneiss be- 
comes northwestward, and the limestone formation outcrops 
on the plateau from beneath it and is the surface rock to the 
low anticlinal spanning Muddy Brook Valley, a little to the 
north of its line, there is a shallow synclinal like that west 
of it. 
But Beartown Mountain, while having nearly horizontal 
rocks at its south end, has its beds very steeply upturned to the 
north, and hence in that direction it is a deep synclinal. It 1s 
hence like Tom Ball* in being a shallow synclinal at one end 
and a deep at the other, but the shallow is at the opposite 
extremity—the south. 
The rocks of the mountain all overlie the Stockbridge lime- 
stone. They are mainly varieties of firm and well characterized 
gneiss. Fissile dark-gray gneiss, approaching mica schist, an 
a firm less schistose variety of similar color, are common. But 
these vary on one side to a white feldspathic gneiss containing 
a little black mica, in short interrupted lines; and on the other 
side to a quartzose variet , which on weathering becomes at 
surface in appearance a curiously pitted quartzite. Again, the 
gray gneiss at the north end is an exceedingly firm gn 
rock, owing to the contortions experienced in the period of bold 
upturning and metamorphism. South. of the railroad half a 
mile west of South Lee, immense blocks of this gnarled gneiss 
lie like ruins on the slope of the adjoining ridge. 
* This Journ., III, v, 85. 
