354 



GRANITE VEINS. 



[Ch. XXV. 



themselves into granite, in a manner analogous to that of the 

 volcanic dikes of Etna and Vesuvius, where they cut and shift 

 each other, or pass through alternating beds of lava and tuff. 



No. 85. 



Granite veins traversing stratified rocJis. 



The annexed diagram will explain to the reader the manner 

 in which these granite veins often branch off from the principal 

 mass. Those on the right-hand side, and in the middle, are 

 taken from Dr. Macculloch's representation of veins passing 

 through the gneiss at Cape Wrath, in Scotland*. The veins 

 on the left are described, by Captain Basil Hall, as traversing 

 the argillaceous schist of the Table- Mountain at the Cape of 



Good Hope']-. 



No. 8G. 



(Irnmtc veins traversing gneiss at Cape Wrath, in Scotland. 



We subjoin another sketch from Dr. Macculloch's interesting 



* Western Islands, plate 31. 



t Account of the structure of the Table-Mountain, &c., Trans. Roy. Soc. Edin., 

 vol. vii. 



