DESCRIPTION OF THE GENERAL SECTIONS. 639 



necting with the antichnal noticed on the first section between Brookline 

 and Mason. In Milford is found a large development of granite, one of the 

 ovoid masses occupying the stratigraphical horizon of the rock quarried 

 in the north part of Manchester. There is no change in the position as 

 far west as the formation occurs, into the eastern edge of Wilton. Not 

 far from its western border there occurs one of the famous quartz bands 

 dipping north-westerly, and reappearing in the eastern part of Temple. 

 Between them the rock is mostly a long, narrow strip of Rockingham 

 mica schist, with several small, subordinate folds, the western part hav- 

 ing a less inclination than the eastern. The quartz of Temple lies in a 

 narrow band of Lake gneiss, followed on the west by the mountain mass 

 of mica schist in Pack Monadnock, dipping west. In Peterborough the 

 western edge of the mica schist makes a synclinal trough; and another 

 gneiss area shows itself, with two or more folds in it. In the west part 

 of the town and in Dublin the porphyritic gneiss succeeds. This forma- 

 tion occurs along two different lines in Jaffrey, each believed to extend 

 beneath both the Peterborough gneiss and the ferruginous Montalban 

 rocks of south-eastern Cheshire. Mt. Monadnock follows next. This is 

 believed to belong to the Kearsarge andalusite group, and to overlie un- 

 conformably the Montalban rocks. In structure it seems to be a double 

 synclinal, and it rests upon a basin-shaped arrangement of strata. The 

 Montalban strata on the west side in Marlborough dip easterly generally, 

 and contain patches of Concord granite. In Swanzey there is a broad 

 Bethlehem band, with nearly uniform high easterly dips. It overlies the 

 Winchester and Chesterfield anticlinal porphyritic gneiss area. A little 

 Montalban gneiss skirts this on the west, followed by the Coos group, 

 which exhibits the common structure of two basins side by side. In the 

 Connecticut valley it is followed by an older ridge of Cambrian slates. 

 West of the slate the structure is exactly the same with that west of Fall 

 river on Section I, with Calciferous mica schist on both sides of the 

 hornblende schist anticlinal. Denudation has cut through this horn- 

 blende in West Brattleboro', and displays the underlying arched gneiss, 

 which may correspond either with the Bethlehem or Lake division of 

 New Hampshire gneiss. I once calculated the amount of erosion from 

 this arch, finding that 950 feet of gneiss and 2,640 of hornblende were 

 required to fill out the gap. 



