GEOLOGY OF THE MERRIMACK DISTRICT. 555 



schists at the south end of the quarry, and the two rocks adhere together, 

 though not firmly. In Bodwell's opening there is a plain line of separa- 

 tion between the two, almost a fault. The granite is apt to be of inferior 

 quality when it approaches the walls. The material is related to the Con- 

 cord, but it is coarser and breaks more readily into angular pieces. It lies 

 in sheets, dipping io° N. W., while the rock on the east side (Bodwell's) 

 stands vertically, with the strike N. 60° E. On the north sides are very 

 large veins of coarse and graphic granites, standing like chimneys. There 

 are splitting planes in the granite, parallel to the walls. The action of the 

 glacial force in breaking the rock on top of the ground is well shown in 

 these quarries. 



The mammoth road passes near these quarries, behind them, and the 

 rock there is the schistose variety. Farther south, on Hanover street 

 crossing, the gneiss runs N. 50° E., the strata vertical. There are several 

 small anticlinal folds, a yard wide, seen here. A few streets to the west, 

 on the crest of the hill, are irregular and coarse granite veins. Many 

 veins in Manchester consist of nearly pure feldspar. I have occasionally 

 seen limestone seams two inches wide in the gneiss. The twisted rocks 

 east of Sawyer's pond, Hooksett, and Candia lie to the east of the schis- 

 tose ledges holding the granite nodules. They commence at about the 

 crossing of the mammoth road and Hanover street. Ledges occur occa- 

 sionally between the ridge east of the city proper and Massabesic lake 

 composed of this rock. By the Methodist church south of Hallville, this 

 gneiss dips 85° S, 30° E. Half a mile west of the extreme south end of 

 Massabesic lake is a quarry in this rock, the blocks extracted from which 

 have been largely used in the buildings of the city. The foundation stones 

 and steps of the city hall are of this character. Between the pumping 

 works and Massabesic lake the gneiss dips 80° S. 60° E. The most south- 

 east ledges of this rock observed are about a mile south of the lake, in the 

 south-east part of the town, dipping 65° S. 50° E, The very corner, for 

 half a mile, is occupied by a coarse mica schist. The change is first 

 indicated, in proceeding south-east, by the enormous blocks of the schist 

 by A. D. Coming's. Gneiss dipping north-east occurs on the promontory 

 at the north-west end of Massabesic lake, a short distance within the town 

 of Auburn. The north end of the lake is sandy and swampy, but a large 

 promontory west of the village is composed of gneiss dipping N. 70° E. 



