410 STRATIGRAPHICAL GEOLOGY. 



southward to this point. It resembles in shape the areas in Hanover and 

 Lyme, and, Hke that in the latter town, it is surrounded by newer rocks. 



2. MONTALBAN SeRIES. 



The rocks that appear to belong to this series are found in the south- 

 west part of Charlestown and in the north-west part of Walpole. In 

 some locahties we have a gneiss that resembles the common or Lake 

 gneiss, but still it is not identical with it, while elsewhere the rocks can- 

 not be distinguished from those we have referred to the Montalban series. 

 If the whole of the rocks of this area do not belong to the latter series, 

 the more compact variety of gneiss being the lower division, it would 

 naturally be classed with the Lake gneiss, — yet I suppose they all belong 

 to the Montalban series. Like many other outcrops of rock in the state, 

 it is a somewhat oblong area, nearly as wide as it is long, and presents 

 rounded contours, both in its northern and southern prolongations, 

 though it is more abrupt on the south than on the north. It begins in 

 the hills north-east of South Charlestown, and widens so that opposite 

 Langdon Centre it extends over a space of two and three fourths miles ; 

 but in it there is included a band of hornblende gneiss. From its out- 

 crop on Saxton's river to Paper Mill Village, it is not far from ten miles 

 in width. It has its southern limit about a mile and a half south of 

 Drewsville. The rock varies considerably in texture. Along its northern 

 border, on the west to its southern outcrop on Saxton's river, through 

 Langdon, and at Paper Mill Village, we find the variety that is coarser 

 in texture, and it is like some of the common or Lake gneiss of the At- 

 lantic system. This rock, however, at the falls carries fibrolite, which is 

 unknown in the common gneiss. Going from South Charlestown tow- 

 ards the south-east, through the pastures that slope to the north, there 

 are many ledges of the gneiss that have segregated veins; and in the 

 coarse we find a band two feet wide of the finer variety, like that at Cold 

 River bridge. 



The points where this rock comes in contact with those that surround 

 it are all concealed by drift. At Langdon Centre we have the gneiss at 

 the school-house, and a mica schist in front of the church. The gneiss 

 has an easterly and the schist a westerly dip, showing clearly their un- 

 conformability. At Bellows Falls, in the gneiss beside the fibrolite, there 



