247 



meliipliyr pebbles, altliouob thev luive not been exactly identi- 

 fied with any mass of nielaphyr now exposed to observation, 

 lend some support to the view that there is or has been in this 

 vicinity a body of mclaphyr of more recent date than the great 

 bed which, as we have seen, belongs near the base of the 

 conglomerate series ; for certaiidy it is not easy to see how 

 melaphyr covered by a thousand feet of conglomerate, sand- 

 stone, and shale, could have yielded these pebbles to a still higher 

 part of the same conformable series of strata ; but a limited 

 eruption — dike, laccolite, or surface flow — at the close of the 

 conglomerate series would explain the phenomena. It should 

 be added that the outcrops of melaphyr nearest to the pebbly 

 slate and upon or against which it seems to rest, are of wholly 

 different character from the enclosed fraj^ments, beino; o-reenish 

 and profusely amygdaloidal. 



The outcrop of slate is almost continuous northward across 

 the outlet of the swamp to the ledge of beautifully jointed 

 slate which projects somewhat into the cove. The breadth 

 of the slate here is fully 100 feet ; but the dip is lower, 

 varying from 60° near the melaphyr to 55° at the top of the 

 bed. The lower half of the bed is very imperfectly exposed ; 

 but it is clear now that the conglomerate layers near the middle 

 of the bed are as limited in this section as in the first, and that 

 there is no appreciable break or displacement, and hence that 

 the compensating faults bounding this ledge on the colored 

 map are not needed. The jointing of the slate in this ledge is 

 exceptionally perfect, yielding many fiat-surfaced, sharp-edged, 

 crystal-like blocks ; and certain layers contain scattering cubic 

 crystals of pyrite. 



A short beach now interruj)ts the slate, but the background 

 of melaphyr continues without deviation ; and toward the 

 north end of the beacli the slate, reapj^earing, presents an 

 interesting contact with what ap})ears to be a north-south dike. 

 The melaphyr along this beach, which has been well exposed 

 by quarrying, is the dark gray, semi-crystalline, and sparingly 



