DESCRIPTION OF THE GENERAL SECTIONS. 643 



has not yet been determined. The same group extends through Somers- 

 worth and the south part of Rochester, and there is an antichnal in it. 

 The enormous sand plain of Rochester and Gonic obscures the under- 

 lying rock ; but in Barrington is a considerable Rockingham schist, with 

 the uprising of an ancient gneiss in the south part of the town. In the 

 west part of Barrington the Rockingham rock reappears, followed by the 

 gneiss of the Bow lake and Northwood region, in which there is an anti- 

 clinal, and the westerly dips prevail through Northwood, underlying the 

 next Rockingham band through Epsom. This shows us the basin struct- 

 ure, resting upon Lake gneiss in Northwood on the east, and the Montal- 

 ban in Chichester on the west. In Chichester and Pembroke the dip is 

 north-westerly, so that this White Mountain series is anticlinal in form. 

 Next the broad sand plains of Concord cover most of the ledges. The 

 section passes across the north end of the oval granite area of Concord, 

 and the smaller patch north-west from Pine hill. The same north-west 

 dip prevails through this formation in the north part of Concord, includ- 

 ing the interesting band of white quartz at West Concord. This Montal- 

 ban ridge is not crossed at right angles by the section, as it runs between 

 north-east and east. Before reaching the west line of Concord we dis- 

 cover the later ferruginous slates, with dips at such diverging angles as 

 to suggest the presence of one or more foldings. At Contoocookville 

 another Concord granite area presents itself, following an outcrop of the 

 ancient porphyritic gneiss on the hill south from Tyler's station. The 

 dips of this and the accompanying ferruginous schists are easterly, all 

 overturned. West of the Contoocook granite is another part of the 

 ferruginous group, apparently synclinal in aspect, with soapstone in the 

 edge of Warner. The section nearly crosses the Montalban of the south- 

 east part of Warner, carrying the quartz and limestone, and evidently a 

 repetition of the West Concord exposures. The ferruginous slates to the 

 west of this Montalban upheaval dip westerly, folding over the underlying 

 formation. Next follows a long breadth of porphyritic gneiss from Hen- 

 niker to Washington. This consists of a series of folds, an anticlinal in 

 Henniker, followed by a synclinal to accommodate the hard schists oc- 

 curring along Warner or Harriman brook; a second anticlinal east of 

 Day pond, and the succeeding basin holding the Lake gneiss area about 

 Bradford pond ; another repetition in the same order in the south part of 



