522 STRATIGRAPHICAL GEOLOGY. 



from Bog pond, the dip is 80° S. 70° E., and it is succeeded by a hard 

 quartzite having the same position. The raih-oad cut in the ridge south 

 of Danbury station is through this formation. 



Next we cross through Wihnot (Fig. 84). This rock first appears on the 

 east, between Potter Place and West Andover, standing vertically. Near 

 the west point of Andover, in Wilmot, the dip of the well characterized 

 rock is about S. 70° E. At Wilmot centre the stream falls over ledges of 

 this rock, dipping 50° in the same direction. A mile west, by a saw-mill, 

 there is a layer of hornblende rock, a great rarity in this formation. With 

 it are the usual types of this rock, including layers with feldspar crystals 

 three or four inches in length. These all dip like the last. By C. Rowe's, 

 a little farther west, there is a magnificent display of these rocks, dip- 

 ping the same way. Mica schists and porphyritic rocks with a dark base, 

 having sparingly disseminated crystals of feldspar, occur here. By a small 

 mill west of the " Gay stand," in the west part of Wilmot, the mixed por- 

 phyritic and common gneisses dip southerly. By our map this should be 

 the western limit of the formation, but there is a porphyritic gneiss on the 

 west town line, adjacent to Springfield. Our observations have shown 

 the gradual increase of other varieties of rock in passing west from 

 Wilmot, and therefore we may believe the characteristic feature may be 

 almost gone, yet the age not change. Special conditions of deposition or 

 metamorphism may have precluded the formation of the larger crystals in 

 abundance. Along this section line the outcrops of ledge have been rare 

 in the region west of the "Gay stand." Porphyritic gneiss is noted also 

 about a mile east of the Springfield line. These dips recall the "fan- 

 shaped stratification" spoken of by the older geological writers, perhaps 

 resolvable into several closely pressed anticlinals and synclinals. 



In the south part of New London there are large bands of porphyritic 

 gneiss interstratified with the gneiss. The ledges on the south edge of 

 Pleasant pond are abundant. There is a wide contrast agriculturally 

 between the country of the porphyritic ledges south of Pleasant pond, and 

 those southerly from New London centre upon the ordinary gneiss, the 

 latter exhibiting beautiful farms, the former rocky pastures. 



Sutton is nearly all underlaid by porphyritic gneiss. Near the north 

 line, by C. A. Fowler's, the dip is 75° N. 75° W. The main road, through 

 the hamlets of North Sutton, Sutton Mills, and South Sutton, abounds 



