Phenomena of Granite Veins. 



493 



width as a, a, : cl, d, is a third vein ; as is proved by its intersecting 

 the two first. It is six inches wide: c, c, is a fourth vein, two inches 

 wide, intersecting d, d, longitudinally, and distinguished from that by 

 being of a much coarser texture. This is a very unusual occurence; 

 one which I have myself never seen ; and we have here also granite of 

 four epochs ; so that this example, if there be no mistake in its repre- 

 sentation, is a very interesting one. 



r 



c 



(34) Granite Veins in Mica slate ; Williamsburg-. 



In No. 35 a large protruding mass of granite rises from the soil at 

 the north end of a naked ledge of mica slate, which is two rods wide, 

 as represented on the sketch. From this mass of granite an irregular 

 vein proceeds nearly in the direction of the layers of slate, embrac- 

 ing two or three nearly insulated strips of mica slate. I am not 

 aware that any very instructive inference can be derived from this 

 case, except that it seems to me impossible to impute to deposition 

 from water, a mass of granite thus irregularly intruded among the 

 mica slate. It occurs in the west part of Whately. 



