ON COTEMPORANEOUS VEINS. 7 



PL I. Fig. 2. a. represents cotemporaneous veins 

 in mica-slate. 



PL I. Fig. 2. b. represents cotemporaneous veins 

 of granitic gneiss in gneiss, and in some places in 

 contact with the old granite. 



in place of being the oldest rock hitherto observed, it must 

 be one of the newest. It is also equally evident, that if 

 granite be of so new a formation, we should find the sup- 

 posed granite veins issuing from the subjacent granite, 

 and traversing the superincumbent newer rocks. Yet no 

 one ever saw a granite vein in any of the transition or 

 floetz rocks, although their junctions with granite have 

 been carefully examined in many and very distant coun- 

 tries. 



i 



\ A 4 



