538 STRATIGRAPHICAL GEOLOGY. 



porphyritic range, as the ferruginous schists appear at the extreme corner. 

 Possibly the gneiss may just enter the eastern Hmits of Francestown, near 

 Haunted pond. 



The gneiss of Peterborough is beUeved to be an extension of the Dun- 

 barton and New Boston ledges, although isolated, because it lies close to 

 the Greenfield branch of the porphyritic gneiss, which has been regarded 

 as on the same axial line with that in the north part of Weare. The 

 dimensions of this area are correctly given on the map, but little is known 

 of the dips. By Mrs. Chapman's and J. Smith's, near the south town line, 

 the dip is westerly. Gneissic strata appear in Peterborough village, 

 near the mouth of Nubanusit river, standing vertically, and as far as W, 

 French's, a mile and a half north, also a mile to the north-west. East of 

 the Contoocook the gneiss is extensively quarried for underpinning, and 

 is an excellent material for that purpose. The dip is 80° N. 72° E. The 

 same rock extends south-westerly towards Jaffrey. These observations 

 indicate a synclinal structure to this area, but are too meagre to enable 

 us to assert that no other axes exist, as that is of great consequence. 

 The west side of the basin, or that nearest the porphyritic gneiss, is the 

 steepest, as might be expected from its proximity to the older formation. 

 Perhaps the north end of the gneiss area in Royalston, Mass., seen on the 

 map, may be the continuation of this other Antrim range. 



The Manchester Range. This is the most important of all the areas of 

 this rock in the state, because it is traversed by two parallel bands of 

 quartz, certainly thirty-three miles in length in this district, and probably 

 over eighty in all between the remotest points of occurrence. The area 

 may be naturally divided into two parts, — first, that enclosed by the two 

 bands of quartz ; second, that lying to the south-east of them. With the 

 first may be included an inconsiderable portion to the north-west, lying 

 south-east of the anticlinal line indicated by the long narrow band of por- 

 phyritic gneiss in New Boston and Weare. Perhaps, however, it will be 

 best to describe, first, the courses of the two bands of quartz. We may 

 distinguish them by the names of the towns where the bands respectively 

 cross the Merrimack river, or Hooksett and Manchester. Their general 

 course is north-cast and south-west, and of course the Hooksett range 

 lies to the north-west of that denominated Manchester. The history of 

 their exploration and certain facts concerning their distinction were first 



