GEOLOGY OF THE MERRIMACK DISTRICT. 469 



comes in contact with the fibroHte schist. It is nearly vertical, but at 

 one point it dips N. 70° W. 78°. South-west of Avery's, in the edge of 

 Rumney, partly in this rock and in a "trap" dyke, there is a mineral vein 

 that carries galenite. From what I was able to see, it appears to be a 

 very promising lode. 



On the north end of Stinson mountain there is an outcrop of porphy- 

 ritic gneiss in the pasture farthest up that side of the mountain, and it is 

 entirely surrounded by the schist. In the south part of Groton the gneiss 

 has a few crystals of feldspar, but it does not seem to be the characteristic 

 porphyritic gneiss. Farther south, in Alexandria, there is no doubt about 

 the character of the rock, and it is entirely east of the fibrolite schist. 

 The small area of gneiss in the west part of Canaan that contains crystals 

 of feldspar probably belongs to the common gneiss, since in its general 

 foliated texture it does not differ from that rock elsewhere. From the 

 line of Canaan and Orange, the western boundary of the porphyritic 

 gneiss runs a little to the east of south through Grafton and Wilmot to 

 Pleasant pond in New London ; then it turns a little to the west, and in 

 Sutton it turns almost directly west, and goes to Sunapee lake. At Sun- 

 apee Harbor, and on the hill immediately south, we have the porphyritic 

 gneiss associated with a rock that resembles the White Mountain gneiss, 

 and the dip is easterly 70°. North of Sugar river. Straw's ledge in Suna- 

 pee is porphyritic gneiss. In the vicinity of Sunapee lake we frequently 

 have fine-grained granitic gneiss that evidently belongs to this series of 

 rocks. South, on the road from Goshen to Washington, opposite J. 

 Glinn's, we have a fine-grained gneiss enclosing bands of porphyritic 

 gneiss; thence south-east, towards Washington centre, there are gneisses 

 and pyritiferous and mica schists ; but the rock in the south and east 

 part of Washington is chiefly porphyritic gneiss, and a band extends into 

 the north-east corner of Marlow. Its north-western limit is near Sand 

 pond, and the line separating it from the rocks on the north-west runs 

 south-west, probably between F. M. Lewis's and school-house No. 3, 

 thence bending a little north, and extending to a point near the upper 

 part of the letter L of the name of the town on the country map ; thence 

 it sweeps round to the south-east, nearly to the road south of Bald moun- 

 tain. Its south-eastern limit would be marked by a line extending from 

 the south-east base of Bald mountain, and crossing the road running 



