310 GEOLOGY OF OLD HAMPSHIEE COUNTY, MASS. 



that they are downward projections of the roof of the batholite, which has 

 been removed just to their average plane of junction. Such a great batho- 

 hte is well seen in Mount Tekoa, in Montgomery. To one standing on the 

 high ground on the west line of Westtield and looking north the contrast of 

 the white granite and the black schist is strongly marked. On the right the 

 great dome of granite makes the sky-line. To the left its curved surface 

 passes down beneath the mass of the schists of Mount Tekoa. The latter 

 at first mantle up over the dome conformably, and higher up end very 

 obliquely on the contact plane, and are greatly cornigated and cut by 

 many large dikes sent off from the main mass. 



Again, these schists and their limestones, entangled in the granite, 

 have been subjected to the same kind and degree of contact metamorphism 

 as the br(.)ad l:)and surrounding them. The schists became feldspathic and 

 the limestones coarsely crystalline, as described under the head of the Con- 

 way mica-schist, page 197, while the hornblende-schists became pyroxenic 

 (as described on p. 243) or feldspathic with or without the development of 

 pyroxene. I look upon the larger masses as great granitic reservoirs' 

 which have })artly forced and partly melted their way up through the schists 

 to the place where they are found, absorbing much of the material of tlie 

 latter in their jn'Ogress and sending upward and outward a complex radi- 

 ating network of dikes. 



I consider the two great stocks of "tonalite" described below to be 

 partially denuded domes of these great granite batholites, which have 

 melted so much of the gneiss and hornblende-schist into their mass that 

 their composition has been greatly changed, but which, penetrated more 

 deeply, would change to ordinary granite. 



Two bands of homblende-schist may be traced right up to the Belcher- 

 town stock on the soiath, and reappear again with their attendant beds upon 

 the north, and a single very thick bed can be followed up to the Hatfield 

 bed on the north, and in traces dipping toward it along its western side. 



The hornblende-schist west of Belchertown village, cut by numerous 

 dikes of granite, becomes impregnated with feldspar, and its fragments have 

 their hornblende largely changed to green pyroxene for a foot from the 

 contact plane (this at Kellys Crossing), and farther south beds of augitic 



' See .T. W. Jvuld, The ancient volcanoes of the Hebrides : Jour. Geol. Soc. London, Vol. XXX, 

 1874, pp. 220-300. 



