52 TIREY. GEOLOGY. 



these beds and those of the limestone of Glen Tilt ; and in 

 both cases granite is present. The contortion of beds is a 

 phenomenon of much interest in geology. Although 

 common in the schistose rocks, it is of more rare occur- 

 rence in limestone, and therefore worthy of being pointed 

 .out wherever it exists. It appears to be so obvious a 

 consequence of the posterior disturbances of beds in a 

 softened state, that it is unnecessary to accumulate argu- 

 ments on the subject. In Mar, in Glen Tilt, and in this 

 place, it is either accompanied by the presence of granite 

 veins or occurs in the neighbourhood of granite masses. 

 In many cases the disturbances of the schistose rocks also 

 occur under the same circumstances ; but there are never- 

 theless instances every where of great contortions in 

 all these rocks where granite has not been found 

 in the neighbourhood. It would be generalizing without 

 just grounds therefore, to say that the disturbances of 

 these rocks were produced by the vicinity of granite. 

 Many other causes of motion besides the supposed protru- 

 sion of granite may have existed among the strata which 

 constitute the surface ; but of these our imperfect know- 

 ledge prevents us at present from forming any judgment. 



The phenomenon in Gott Bay now described is of some 

 importance in the history of gneiss. It has been said that 

 all the granite veins in gneiss are contemporaneous ; a 

 term of which the meaning is not always very definite. 

 In this case it is perhaps meant, that the granite vein is a 

 necessary portion of the gneiss ; each being formed in- 

 dependently of the other, although in a state of contact 

 and mixture, and the appearance of a vein being merely 

 incidental. But in the rock under consideration the 

 game body of granite which traverses a bed of gneiss, 

 traverses an approximate bed of limestone, without 

 change of direction, continuity, magnitude, or cha- 

 racter : a phenomenon possessing on this supposition the 

 highest degree of improbability, and requiring circum- 

 stances of which we can form no conception. 



