TRANSITION ROCKS. 127 



It was first stated, that they were formed of newer granite, 

 and, if properly examined, would be found to cut the old gra-r 

 nite as well as the rock which rested on it. 



This opinion was -once very strenuously supported in this 

 country ; but as facts would not bear it out, it was abandoned. 

 I find, however, in a recent publication, something similar to 

 it maintained by De Luc, who asserts that the veins at St Mi- 

 chael's Mount are not granite, but merely quartz, which tra- 

 verses the granite as well as the stratified rock. I cannot com- 

 prehend how De Luc could have been so much deceived at 

 this place ; as simple inspection of the smallest specimen, will 

 prove that he was mistaken. 



It was next said, that the veins in question were not true 

 veins, but such as are termed Cotemporaneous. To support 

 which, it was boldly asserted, that they never extended beyond 

 the limits of such rocks as were composed of the same mate- 

 rials, gneiss and mica-slate. 



I trust it is now distinctly shewn, that they do extend be- 

 yond these limits, and likewise that they traverse rocks from 

 which, by no method of reasoning, it can be supposed that 

 they could possibly be formed by secretion. 



The last opinion is that which has recently been brought 

 forward by Dr Berger *. After describing the granite veins of 

 St Michael's Mount, he proceeds to say, that they are simply 

 elevations on the plane of the granite existing previous to its 

 being covered by the stratified rock ; that the spaces between 

 them were filled up as the grauwacke was deposited ; and hence 

 the abrasion of the surface, brought to light a section, which 

 has merely an appearance of veins. 



Were the devotion of Dr Berger to his master less conspi- 

 cuous in his geological disquisitions, I should be inclined, on 



the 



* Transactions of the Geological Society, vol. i. p. 147. 



