Phenomena of Granite Veins. 481 



near the foot of the hill, is to the right of the vein at h ; and as we 

 ascend the hill, we find the slate curved upwards near the vein more 

 and more, as is shown in the drawing. Indeed, the granite of the 

 vein seems to lie on the elevated edges of the slate : so that the lower 

 side of the vein dips southeasterly : and does not cut the slate per- 

 pendicularly. These facts would seem to evince, that the vein made 

 its way through the slate, not along the line of greatest pressure but 

 on the north side of it; probably because the slate there yielded most 



(11.) Veins and Masses of Granite in Hornblende Slate ; Ackworth, N. H. 



readily. We may suppose the melted granite below, to have gradu- 

 ally elevated the slate, until at length it burst its way laterally through 

 that rock. Such cnses, I believe, do sometimes occur in existing vol- 

 canoes. 



The masses of granite /;, arid c, are probably other examples in 

 which the same molten matter burst its way laterally through the 

 slate. And it is an interesting fact in regard to the mass b, that in 

 some places it still projects over the slate several feet, forming in fact 

 an overlying mass. Instances of this kind I have rarely met with in 

 the granite of N. England. I recollect but one case precisely re- 

 sembling this ; and that is in the town of Carlisle, about two miles 

 west of the meeting-house, near an unfrequented read ; where the 

 granite has spread over mica slate several feet. But the sketch of 

 that spot I have unfortunately lost. 



The following sketch, however, which I took several years ago, 

 appears to have a resemblance to those just described; especially to 

 61 



