6 JOSEPH H. PERRY 



eastern part of the area of our map is prevailingly porphyritic, 

 and closely resembles the granite already described, except that 

 the phenocrysts are frequently larger and sometimes show a 

 granulated border. The granite of these areas is frequently 

 foliated near the schist border, and parallelly to the lamination 

 of the schist. 



On looking at the map, it is seen that the granite in the south- 

 ern part of this area occurs in lobes, two of which are connected, 

 while that in the northeastern part is in the form of a long tongue 

 extending far into the schist, though not visibly reaching the 

 southern granite area. These are probably parts of an extensive 

 batholite which, possibly, extends even under the mountain. 

 This granite incloses fragments, both large and small, of the 

 neighboring schists. Among these may be recognized some of 

 the light gray, quartzose mica schist thoroughly brecciated, and 

 some of the fibrolite and andalusite schists. In the last the 

 andalusite crystals have been generally, if not always, changed 

 as has been described before. Inclosed in the granite may be 

 seen prismatic masses of sericite entirely separate from, though 

 in the vicinity of, the schist, which probably represent andalu- 

 site crystals which were dissolved in the magma, and afterwards 

 crystallized out and sericitized. 



It is difficult to decide, in some parts of this area, where to 

 draw the boundary between granite and schist, because there is 

 frequently a zone of alternating bands extending in the direction 

 of the strike. Such an area is represented in the extreme 

 western part of the geological map, and also in cross-section. 

 The meaning of such an area is that the surface of contact 

 between schist and granite batholite was a ragged surface — 

 the granite having penetrated the schist at intervals, and pushed 

 apart the vertical laminae. The erosion has brought the land 

 surface down so as to make a section through this alternation. 

 If the land surface had been lowered somewhat less, the rock at 

 the surface would have been schist ; whereas if the land 

 surface had been lowered somewhat more, the rock would have 

 been then all granite. As it is, the extension of the batholite 

 is but a short distance below the surface. 



