GEOLOGY OF THE MERRIMACK DISTRICT. 56 1 



dipping 85° N. 50° W. On the town line, at A. Ordway's, the dip is 70° 

 N. 40° W., and the beds of granite are noticeable for their large size. 

 For a few rods a south-east dip was noticed. On the west road it is at 

 least three miles before coming to the next observation, at Mrs. Black's, 

 dip 70° N. W. On a road farther south I noticed, near J. C, Drew's, very 

 abundant ledges on high bluffs, facing westward. Other ledges crop out 

 at H. N. Campbell's and R. Taylor's. Perhaps these dips diverge suffi- 

 ciently to authorize us to believe that there exists here an anticlinal axis. 

 There is more gneiss in the south-east part of Derry, said to be granitic, 

 and to dip N. 50° E. Passing through North Salem we find the same 

 rock standing on edge. At the school-house next D. Dunlap's the dip is 

 40° S. 60° E. Near Merrill & Bailey's factory the dip is vertical again. 

 At B. Foster's the direction is to N. 35° W. On reaching the westerly 

 branch of Spicket river we come to a narrow range of sienite, supposed 

 to extend beneath the village of Salem as far as I. T. Foster's, nearly 

 three miles. Fig. 93 embodies these observations through Salem in 

 graphic form. In the west edge of the village the gneiss dips 80° N. 75° 

 W. A coarse feldspar rock is interstratified with it at W. G. Crowell's, 

 two miles north-west. It is a coarse schist east of E. Sanders's, but far- 

 ther west the same gneiss dips 80° N. 50° W. North-west from Policy 

 pond are several exposures of the best defined Lake gneiss seen in this 

 neighborhood, dipping 85° N. 50° W. It is succeeded by a modern mica 

 schist beyond the school-house. These ledges are traversed by segregated 

 veins, and the series of outcrops just named represent a section across 

 the whole belt. The strata are more distinctly monoclinal here than in 

 Hampstead and Derry. West of the Salem depot are quarries of granite, 

 or rather of this gneiss, the dip being distinctly 50° N. 70° W. It 

 behaves just like the Concord granite in respect to its excavation. It is 

 traversed by the same vertical and nearly horizontal joints. There is a 

 cap of inferior rock over it also. This is at Gage's quarry. At B, A, 

 Cole's, a little to the east, the material is more granitic, and has large 

 masses of mica schists caught in it, in conjunction with large veins of 

 coarse granite. Passing westerly into Windham, on top of the hill a short 

 distance south-west from Policy pond, is a ledge of dark, fine-grained 

 gneiss, dipping north-west. Farther along are mica schists, holding a 

 similar position, at the south end of Corbett's pond. At the centre of 

 VOL, II, 71 



