GEOLOGY OF THE WHITE MOUNTAIN DISTRICT. 225 



is found to be quite precipitous, allowing only a scrubby growth of trees. 

 From one fourth of a mile west of Little river to the slope towards New 

 Zealand pond, including the precipice and the divide, the rock is a fine- 

 grained porphyry carrying numerous distinct grains and crystals of quartz, 

 weathering whitish. On the east it is supposed to join the finer-grained 

 variety of Conway granite. 



In ascending the most northern Little River mountain from the north, 

 after leaving gneiss, I found what is termed in my note-book a feldspathic 

 sandstone, much like the rock of Mt. Carrigain. At the very base of the 

 mountain a compact, dun-colored porphyry is present. The west side of 

 the mountain is like the ridge farther south, made of porphyry, with nu- 

 merous crystalline grains of quartz. It also has black patches of dark 

 porphyry in it. Our specimens from these more northern localities have 

 been unfortunately lost, through malevolence, — the only ones collected 

 by us from the whole mountain region not at present safely in the mu- 

 seum. It is likely that the porphyry is continuous from South Twin to 

 the northern Little River mountain. 



There is also a small porphyritic area on the northern slope of the 

 water-shed between Little and Ammonoosuc rivers, about a mile south 

 of Twin Mountain station. Its place and dip of 65° S. 25° E. are indi- 

 cated upon Fig. II. 



3. Mt. Carrigain Area. 



The principal portions of Mts. Carrigain and Lowell are known to be 

 composed of dark-colored porphyries, with disseminated small crystalline 

 bunches of orthoclase, the general character corresponding with the rock 

 upon South Twin. It is likely that the rock of Mt. Anderson is the same. 

 Mt. Lowell is known in the older writings upon the White Mountains as 

 "Brick-house mountain," so called from the unusual abundance in it of 

 the red orthoclase crystals. It seems to stand east of the straight line 

 from Carrigain to Anderson, though not so represented upon any map 

 made before ours in the atlas. There is a slight resemblance between 

 the stratigraphical position of this porphyry and the slate on Mt. Willey, 

 Both rest upon the Conway granite, and they dip in opposite directions, 

 while between them is a much lower territory composed of the supposed 

 older rock. A believer in metamorphism might find resemblances be- 

 voL. II. 29 



