1813.] 



Transition Roch of PVerner. 



427 



stratified rock, and are cut off by the granite in the same line 

 without any interruption. 



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

 the greywacke had been deposited on the granite in the way lie 

 supposes, it is natural to conclude that it would have been 

 arranged in lines parallel to the sides of the elevations, some- 

 what 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 ; conse- 

 quently, 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. Button by the appearance of 

 these veins meets every difficulty : they conveyed to him evidence 

 of being derived from a source of the greatest violence ; and 

 also that nothing but liquid matter injected from below could 

 have created the disturbance among the stratified rocks, so con- 

 spicuous when in contact with granite. As it is a a self-evident 

 position that a rock which is cut by a true vein must have 

 existed in a solid state previous to the formation of that vein ; 

 so is it equally obvious that if the vein can be traced into an 

 adjoining mass, of which it is found to be a part, that mass 

 must stand in the same relation, in point of period, to the rock 

 which contains the vein, as the vein itself does : as also that if 

 pieces of one rock be found imbedded in another, the including 

 rock must have been of subsequent formation to the included. 

 No theory, however, but that of Dr. Hutton can account for 

 these appearances : to nothing but force can the position be 

 attributed, which the stratified rocks have assum.ed in the vicinity 

 of the unstratified ; and nothing but matter injected in a liquid 

 state could possibly have formed the shoots which traverse from 

 the great mass of granite perforating the stratified rock, and at 

 the same time envelope detached fragments of that rock. As 

 the idea of violence in these operations has been so frequently 

 combated, I cannot refrain from noticing here a very striking 

 mark of it I met with at Coul in Koss-shire, when visiting Sir 

 George Mackenzie. There the strata of gneiss are much dis- 

 turbed by the invasion of granite veins: near which, on tlie 

 outside curvatures of some of them I perceived rents siuiiiar to 

 what we might expect on bending a flattened mass of clay, 

 nearly deprived of moisture. I am fortunately enabled to present 

 to the Society specimens illustrative of this interesting fact. 



In the theory of Dr. Hutton we find also some grounds to 

 account for the diminution of grain in the substance of the 

 veins. The same cause to which in a former paper I attributed 

 the gradation in the texture of greenstone, may be supposed to 

 liiave acted here. It does not^ however^ observe an equal con« 



