GEOLOGY O'.' THE WHITE MOUNTAIN DISTRICT. 235 



147, 149-152, 160, 289-293, 297-301, — belong to this group, and that 

 they extend in a narrow belt north-easterly from Iron mountain, in Bart- 

 Ictt, through Jackson, essentially parallel with the range in Coos county. 

 There seems to be an anticlinal axis in it, also; but this probably does 

 not express the proper structure of the whole mass. The strata are gen- 

 erally monoclinal, constituting an overturn synclinal, like the rocks on 

 the Mt. Washington carriage-road. 



PEQUAWKET .SERIES. 



The last of the groups of rock among the White Mountains to be con- 

 sidered are the Mt. Pcquawket or Mt. Mote breccias and porphyries. 

 The andalusite slates are the most recent of the stratified formations 

 known to exist in this district; and consequently a breccia formed by 

 its dismemberment, as well as the accompanying feldspathic ejection, 

 must have been of later origin. The Pequawket and Mote areas are 

 alike in composition, and may have been parts of the same original mass, 

 cut in two subsequently by the Saco river. In the west parts of Albany 

 and Watcrville are other breccias, perhaps to be referred to the same 

 eruptive period. If so, the porphyry period is probably coeval with it. 

 There is also a mass of somewhat similar material constituting the more 

 northern Twin mountain, while upon Mts. Willard and Tom the breccia 

 is identical with that of Pequawket. For convenience, we will describe 

 in turn the breccia and the rocks associated with it in each area, consid- 

 ered geographically. 



Mt. Pequawket. 



The state of our information respecting the structure of this mountain 

 has been given partially in Volume I, page 43. Very similar statements 

 concerning this mountain were made by Dr. Jackson, in his report, which 

 I will quote for the sake of perfecting the record of the history of opin- 

 ions about our geology. 



On ascending the mountain on its south-eastern side, we came first to a coarse 

 variety of granite, consisting of feldspar and quartz, without any mica, which is over- 

 laid by a breccia of granite and argillaceous nlate, above which rest the regular strata 

 of argillaceous slate, which run N. 75° E., S. 75° W., and dip to the N. N. W. 30°, the 

 strata dipping towards the mountain. This slate is compact, and is much broken and 

 twisted, so that it would not answer for covering roofs. Occasionally a few good slabs 



