GEOLOGY OF THE WHITE MOUNTAIN DISTRICT. 239 



]\It. INIOTE. 



There is an extensive area of brecciated porphyries, similar to those 

 just described upon the two mountains west of North Conway, between 

 the Saco and Swift rivers, known as the Mote mountains. On examin- 

 ing the specimens, in connection with the full description given of this 

 area upon pages 14S-150, it appears that there is a considerable porphyry 

 present distinct from the breccia. It occurs all the way from Bartlett to 

 the summit of the ridge following up Stony brook, above Diana's Bath 

 and Farnum's, in all cases beneath the breccia. The more central part, 

 or the north peak, contains the greatest amount of andalusite slate frag- 

 ments, the pieces averaging coarser than on Mt. Pequawket. At the 

 southern extremity, as at the western, in the other case, there is an 

 abundance of porphyritic cement without slate. 



The identity of the Mt. Mote with the Mt, Pequawket breccia seems 

 well established. But farther west in Bartlett, Albany, Waterville, etc., 

 there are breccias associated with porphyry composed of different classes 

 of fragments, still with a similar cement. As we found a variation upon 

 Mt. Pequawket, occasioned apparently by proximity to particular ledges, 

 it would seem probable that all the breccias with feldspathic paste must 

 be of the same age, and formed subsequently both to the eruption of the 

 original porphyry and the deposition of the slates. The area in the west 

 part of Albany contains fragments of mica schist, labradorite, porphyry, 

 and quartz, and, when near the outcrop, bits of bright red compact feld- 

 spar. These ledges are connected directly with the breccias of Mote 

 mountain, and have been noticed upon page 148. Another case has 

 been mentioned as occurring about the head waters of Sabba Day brook 

 in Waterville. Wherever boulders of red porphyry occur, there are many 

 of a brecciated character, showing a probability of their formation at the 

 same time with those in Albany, Bartlett, and Chatham. This was re- 

 marked in particular at Waterville. 



Tw^iN Mountain. 



After ascending Twin mountain, in 1871, which was before the exami- 

 nation of the Bartlett and Chatham area, I referred the rock of the north 

 peak to the Albany granite ; but later investigations prove that it belongs 



