384 Egglcston — Eruptive Rocks at Cutting sville, Vt. 



bearing phase of the pulaskite and contemporaneous 

 with it, or, as just suggested, a distinctly later intrusion. 



Smaller igneous-rock areas. — The two smaller areas 

 north of Granite Hill appear to be parts of one irregular, 

 composite intrusion, fed from the same magma reservoir 

 as the main body. It is quite possible that the northern 

 areas are continuous with the Granite Hill mass, beneath 

 the cover of drift and alluvium in Mill River Valley. If 

 so, this would increase the length of the area of the Gr'an- 

 ite Hill stock by about three-quarters of a mile, and give 

 it a pronounced northward elongation. 



The northern eruptives, where exposed, are much more 

 involved with the country rocks than is the case on 

 Granite Hill. Contorted and brecciated gneisses fre- 

 quently alternate with eruptives along the railroad, and 

 flank them on the northwest. The geological map, owing 

 to the limitations of its scale, gives a quite inadequate 

 impression of the intricate relations between eruptives 

 and country rock, especially in the case of the more 

 northern area. 



The rocks of the northern areas resemble those on 

 Granite Hill, but nordmarkite and the more basic phases 

 of essexite are absent. Thick dikes of camptonite with 

 numerous inclusions are the more impressive features in 

 the northern areas. 



Although not so well shown as on Granite Hill, the sye- 

 nite of the northern areas is nevertheless clearly intrusive 

 into the essexite, probably vertically, judging from lim- 

 ited contacts and nearly vertical flow lines in some of the 

 syenite. The essexite carries occasional xenoliths of 

 quartzite, hornblende gneiss, and possibly of dolomite, 

 and is probably a quite irregular intrusion. The syenite, 

 although not chemically or microscopically studied, is 

 regarded as partly pulaskite and partly biotite syenite 

 (with some hornblende). The latter has been mapped 

 under the same symbol (2, fig. 1) as the hornblende-bio- 

 tite syenite of Granite Hill, which rock it most resembles. 



Breccia mass. — About three quarters of a mile north of 

 the small areas of eruptive rock just described, there is a 

 body of breccia, shown in fig. 4. Though not closely 

 studied it appears to represent shattering by faults. 

 The constituent fragments, never more than a few centi- 

 meters in diameter, are composed of quartzite, with sub- 

 ordinate schist and gneiss. In its southern part the 



