GEOLOGY OF THE LAKE DISTRICT. 60/ 



sienitc with the gneiss may be well seen at the north end of the mass. 

 To the south of S. Dinsmore's in Sandwich, the gneiss dips 75° S. E.; and 

 the sienite rests upon it at the same angle. Joints dipping 5° N. cut 

 both rocks. Dykes of crystalline compact feldspar, three feet wide, cut 

 the gneiss at a considerable distance from the sienitic mass. Back of S. 

 Smith's, in the north-western part of Moultonborough, the joints in the 

 sienite run north and south, and stand vertical. At M. Hutchins's, on 

 the east side of Round pond, the two rocks seem to meet on the strati- 

 fied plane of 80° S. 85° E. At the south end of the hill the junction of 

 the two rocks is concealed by drift ; and the dip of the gneiss is uncer- 

 tain. At Moultonborough centre the gneiss is hornblendic, and it is 

 believed to dip westerly. Many of the ledges at the west base of Ossi- 

 pee dip west also. That would indicate that the Red Hill sienite came 

 up through a fault along a synclinal line. I have a suspicion that the 

 conical mountain just in the edge of Holderness, on the north shore of 

 Squam lake, will prove to be composed of sienite. 



The Belknap Area. This lies in Gilford, Gilmanton, and Alton. It is 

 eleven miles long, and six miles in its greatest width, the general direc- 

 tion being parallel to the lake. The most northern exposure is opposite 

 Thompson's island in Gilford. It comes in contact with the porphyritic 

 gneiss, and it is more fine-grained than usual, full of dark hornblendic 

 spots, and brecciated. On the beginning of the mountain range, a mile 

 and a half south-west and back of J. Smith's, the rock is coarser. The 

 northern of the two most conspicuous peaks, directly east from the house 

 of N. Weeks, shows a rock of the texture of the Ouincy, Mass., rock. 

 Joints on the summits dip 75° N. 20° W., and also south of east. There 

 is trap dyke there, also, ten feet wide, with the course N. 65° W. Small, 

 reddish feldspathic veins are common. Part way up on the west side is 

 a vein of magnetic pyrites occupying one of the vertical fissures. Green 

 augite occurs on the mountain at some forgotten locality. The gneiss 

 dips 50° S. at the western base of the mountain, with joints, 85° S. E., 

 which may possibly be taken for strata. As the gneiss in West Alton 

 dips westerly, it is likely the Belknap sienite has been exuded through 

 a synclinal fault just like that of Red hill. 



The road from Gilford across the mountain to West Alton shows a 

 fine-grained, brecciated variety of the rock at J. J. Morrill's, where the 



