Phenomena of Granite Veins. 



485 



(17) Granite Vein in Gneiss, Zoar Bridge, Ct. 



Nos. 18, 19 and 20 are representations of insulated masses of mica 

 slate and gneiss in large veins of granite. The vein in No. 18, 

 which is in the north part of Shutesbury, is ten feet wide, and the in- 

 sulated mass of gneiss is almost three feet across in its longest direc- 

 tion. In No. 19, which is in Conway, the vein is fifteen inches wide 

 and the mass of mica slate (which is the rock traversed by the vein,) 

 is thirty inches long. In No. 20, the imbedded mass of mica slate is 

 eight feet wide and ten feet high ; the layers standing perpendicular, 

 and coinciding with those of the mica slate generally in that place. 

 In all the cases described, it seems impossible to doubt but the schis- 

 tose rock is perfectly insulated in the granite ; and if so, does it not 

 point to an igneous origin for the granite ? 



(18) Mass, of Gneiss in Granite; Shutesbury. 



