Phenomena of Granite Veins. 



483 



Granite Vein in Mica and Hornblende Slate. 

 Williamsburg-h. 



runs here in the direction of the strata of mica slate. The dark stra- 

 tum a, a, t is hornblende slate, or perhaps amphibolic mica slate : and 

 it appears to have been cut off and separated laterally a few feet. 

 The upper mass of hornblende and mica slate is insulated in the 

 granite, the narrowest vein of granite, however, being only three inch- 

 es wide. 



No. 15 represents two irregular masses of granite connected by a 

 vein, or rather by two tubercular masses of the same rock. They 

 occur in hornblende slate, two miles northeast of West Granville 

 meeting house, on the road to Blanford. The strata of this slate usu- 

 ally stand perpendicular. Where thus penetrated by granite, how- 

 ever, the dip varies from 70 to 90 west ; and its layers are exceed- 

 ingly contorted. Their usual direction, also, is very much altered in 

 some parts of the sketch. The sketch embraces a space of several 

 square rods. 



(15) Granite in Hornblende Slate : Granville. 



