. GEOLOGY OF THE WHITE MOUNTAIN DISTRICT. 1 57 



extending all the way from Pollard's to the top of the south spur of Twin 

 mountain. The difference in height between the two points being 2300 

 feet, it is supposed the granite mass is not less than this figure in thick- 

 ness. 



Frauconia region. The discovery of the proper succession of the 

 granites and porpliyry was made in Lincoln, in a section from the top 

 of Mt. Liberty through the Flume to Mt. Flume. [See p. 42, vol. i.] In 

 this section the typical character of all the members is well developed. 

 The Conway granite is exposed for 600 feet in thickness, the Albany 

 about 1000, and the porphyry at least 600 more. The lov/er granite has 

 planes dipping 30° S. 38'^ E. Near its upper boundary they dip in the 

 opposite direction. The Albany granite is of that variety which shows 

 very rounded feldspar masses, looking like i:)ebblcs at a distance. At the 

 Flume, a few rods west, in the Pemigewasset river on the way to the 

 Flume house, and at the Pool, are excellent outcrops of the lower granite. 

 The Flume is one of the most attractive objects in the neighborhood. It 

 is a chasm excavated out of the Conway granite, three or four hundred 

 feet long, twelve to twenty feet wide, and over fifty feet high. Its course 

 is east and west. Our heliotype gives a fair idea of its character. On 

 the right hand are the natural walls or joints vv^hich cut vertically across 

 these rocks all over the mountains. On the left are fainter lines nearly 

 horizontal, which illustrate the common position of another set of joints 

 possibly corresponding with the layers of accumulation. In the distance 

 may be seen a boulder of the Franconia breccia, caught between the 

 walls, suspended overhead, and apparently needing but a slight push to 

 cause it to drop. An enlarged view of it appears upon another plate, 

 whereon the slight attachment of the stone to the walls is more distinctly 

 exhibited. It is estimated to be fifteen feet in the longer diameter, eight 

 feet wide, or across the chasm, and twelve feet long, east and west. The 

 lower part may be twelve or fifteen feet above the head of the visitor 

 looking up from the platform. The stone probably came from Eagle 

 Cliff, four miles away, in the glacial period. It was transferred by ice, 

 and most likely arrived before the formation of the Flume. 



On following up the stream one comes to a trap dyke consisting of 

 two sorts of material, the outer, the ordinary dark rock common to this 

 neighborhood, the inner, a gray, friable mass, both perhaps twenty-four 



