42 2 THE JOURNAL OF GEOLOGY. 



exceed shearing and the development of the regional schistosity 

 would not be expected. It is nevertheless true that the core 

 rocks, although as a whole more massive than the border series, 

 have in most localities a pronounced lamination not always due 

 to the formation of micas, as in the Mendon series, but frequently 

 the result of a rearrangement of the chemical combinations of 

 the rock brought about by metasomatic and dynamic agencies. 

 This is shown by the formation of amphibolites from some 

 basic eruptive rock and by banding produced by the parallel 

 injection of pegmatitic veins along the schistosity. If the core 

 rocks were below the neutral zone during the folding that induced 

 the regional clearage in the border series, then manifestly the 

 intricate flexing of the inferior rocks was developed before the 

 deposition of the Mendon series ; if the core rocks were above 

 the neutral belt they should have the normal lamination and 

 characteristic folding universally occurring in the upper series, 

 which is not the case. 



A coarse granitoid gneiss and some associated quartzose sedi- 

 mentaries occurring at North Sherburne are characterized by 

 hundreds of minute faults to the square foot, having most diver- 

 gent trends. That this was an area below the zone of neutral 

 motion, thus permitting compensation by faulting or crushing is 

 not tenable since the rocks are not more than 300 feet below a 

 metamorphosed conglomerate, in which no faulting of this nature 

 has taken place. In this phenomena we have more evidence 

 pointing to the conclusion that the core rocks have under- 

 gone many mutations not participated in by the overlying 

 Mendon series and must therefore be separated by an uncon 

 formity. 



The conglomerate-gneiss horizon. — On the west side of the 

 range, the Hitchcocks have colored in this horizon extend- 

 ing in scattered patches beneath the " quartz- rock " from 

 Sunderland on the south to the Canadian boundary, thicken- 

 ing toward the north. A patch is shown at Sunderland and 

 another at Wallingford. Beginning in the town of Ripton, 

 if this interpretation be correct, it extends continuously across 



