AHRAN. GEOLOGY. GRANITE. 345 



them as nearly as possible, in the order qf their super- 

 position. 



Granite occupies the highest parts as well as the 

 largest proportion of the mountains of the northern 

 district. In general character and aspect, it resembles 

 in some places the well known granite of Cornwall, with 

 which it also corresponds occasionally in mineral structure. 

 It is often disposed in prismatic and cuboidal forms, 

 or rather, may be considered as a solid and extended 

 body split into masses of such configuration. When 

 these are of considerable size, and of small dimension 

 in one direction compared with that in the two others, 

 they put on the appearance of beds; a circumstance 

 very conspicuous in Glen Sannox, and which, in more 

 instances than this, has given rise to a belief in the 

 stratified disposition of granite. But there is no con- 

 tinuity in these beds, and they are placed in so many 

 different directions, even within a very small space, 

 while at the same time they show no marks of 

 fracture, or incurvation, that it is impossible to con- 

 template them for a moment without abandoning this 

 opinion. The occurrence of stratification in rocks 

 is a feature so common, that it is not surprising if 

 every structure bearing a resemblance to that which 

 it produces, has been considered as marking a similar 

 origin. A more extensive view of these subjects, and 

 some attention to the magnitude of the scale on which 

 Nature operates, will lead to analogies explanatory of 

 these appearances. These may be found in the foliated 

 disposition of schist, which seems the result of a process 

 somewhat analogous to crystallization, or, to speak more 

 correctly, is one of the various modifications of the 

 concretionary structure. Similar appearances are not 

 uncommon among the other unstratified substances, 

 namely, porphyry, syenite, and the various other rocks 

 of the trap family : as I have noticed in the account 

 of the hypersthene rock of Sky, and on other occasions. 

 It would in itself be sufficient evidence against the 



