"128 REMARKS ON THL 



the above statement, to call his character as an observer in 

 question, having passed over in silence the detached masses 

 of killas, which he could not fail to observe included in the gra^ 

 nite, and which the above hypothesis is as far from accounting 

 for as either of those mentioned before. 



I have only a few specimens (Nos. 39, 40, 41.) to lay before 

 the Society from the veins of St Michael's Mount ; but they 

 are equally interesting and satisfactory. One, exhibits a por- 

 tion of the killas bounded on each side by granite ; another, a 

 portion of two granite veins traversing killas ; and the third a 

 mass of killas included in the granite. 



Simple inspection is sufficient, in the first place, to shew 

 that the opinion of De Luc is groundles with respect to the 

 substance of these veins. One of the specimens also, contains 

 two small veins of quartz, which are of the kind called Cotem- 

 poraneous ; these keep the direction of the seams of the strati- 

 fied rock, and are cut off by the granite in the same line with- 

 out any interruption. 



To the opinion of Dr Berger they also offer some reply. 

 If the grauwacke had been deposited on the granite in the 

 way he supposes, it is natural to conclude, that it would 

 have been arranged in lines parallel to the sides of the 

 elevations, somewhat similar to the coating of bark on the 

 trunk of a tree : but in place of this, the seams of the killas are 

 set at an angle of about 30°, to the planes of intersection with 

 the granite ; consequently, if deposited from a supernatant 

 fluid, they have assumed a very different position from that 

 which either mechanical or crystalline influence would have 

 induced. 



The hypothesis suggested to Dr Hutton by the appearance 

 of these veins, meets every difficulty : they conveyed to him 

 evidence of being derived from a source of the greatest vio- 

 lence ; and also that nothing but liquid matter injected from 



below, 



