162 ASSOCIATIONS OP, ETC. [Ch. VIII. 



8. These veins are sometimes straight, and pretty regular 

 in their thickness; but in general they are more or less 

 tortuous, and gradually become smaller as they recede from 

 the granite. 



9. It occasionally happens that where these granite-veins 

 occur, the slate is intersected by numerous small quartz- veins : 

 some of these are traversed by the former ; others, on the 

 contrary, traverse and heave both the granite-veins and the 

 other quartz-veins. 



