582 STRATIGRAPHICAL GEOLOGY. 



A broad meadow conceals the ledges next, as far as the double road 

 around J. Patten's, where the mica schist changes to dip 45° N. W. The 

 angle of the dip here is much less than by Beaver pond. Next the mica 

 schists dip south-east at three localities, — the valley of West Run brook, 

 at J. Boynton's, and midway between them. This south-east series of 

 outcrops extends for a mile and a half. At J. Low's, north of Ezekiel 

 pond, mica schists dip 80° N. W. Just east of the pond succeed coarse 

 granites. The same occur at E. Hobbs's, on the south side of the pond, 

 dipping 75° N. 50° W. These rocks are chiefly porphyritic feldspars, 

 with hard mica schists, freshly exposed in a railroad cut. Along the 

 Lawrence railroad, west of Mitchell's pond, near the north line of Wind- 

 ham, similar schists and feldspathic rocks occur. Less than a mile south- 

 west from Mitchell's pond is a large amount of feldspathic rock. Farther 

 south, where small bends in the road are conspicuous, the feldspar beds 

 and mica schists alternate. We find granitic rock at D. Kelley's, schist 

 at T. Dinsmore's, and so on to the Lake gneiss, the last half mile of the 

 section being mostly devoid of granite. The last mile of the way shows 

 small bands of quartz, and there are enough large boulders of this material 

 on the surface to suggest the near proximity of a considerable bed of it. 

 The section suggests a general synclinal structure of the whole band, with 

 correspondences on the sides. We find the coarse feldspathic beds on 

 both sides, with the possibility of a quartz bed repeated. The central 

 portion is occupied by a slate, which may perhaps be traced south- 

 westerly to connect with the clay slate of the Worcester county, Mass., 

 range. The mica schists are usually more siliceous than the majority of 

 the Rockingham schists in the other areas, but are not quite the same 

 with the micaceous quartzites of the Merrimack group. There is a mass 

 of Huronian aspect, however, in the north part of Derry, which requires 

 farther exploration before its relations are satisfactorily made out. 



Section II crosses the formation transversely, and we glean the follow- 

 ing facts from it. From Derry station, on the Rochester railroad, to East 

 Derry, the dips are north-west, and the rocks mica schists. No ledges 

 occur anywhere about the village. Between this village and the eastern 

 town line a few ledges dip 70° N. W., and carry large granitic beds in 

 their eastern outcrops. Between Derry west village and the Lawrence 

 railroad depot are mica schists with north-west dip. West of the railroad 



