234? AN ENQUIRY INTO THE [Ch. XII. 



The granite of Arran, like that of Devon and Cornwall, 

 has the bedded appearance which, in detached parts, so much 

 resembles stratification that it has not unfrequeiitly been mis- 

 taken for it. " Nor is this great lamellar texture," observes 

 Dr. Macculloch*, "peculiar to granite. In examining the 

 Cuchullin hills in Skye, I have observed that the syenite and 

 greenstone are bedded as it were in layers, either curved or 

 straight, either horizontal or slightly inclined, resembling so 

 much the disposition of granite beds that even an experienced 

 eye would at a distance be deceived by them ; and some kinds 

 of porphyry also afford examples of a similar disposition." 



Mr. Weaver, also, in his account of the east of Ireland f, 

 concludes that the interior granite nucleus of this region is 

 not stratified : but he adds, " that from repeated observations 

 in several quarries and other denuded portions, I am led to 

 infer, that the superficial parts or outskirts of this rock oc- 

 casionally exhibit a disposition towards stratification." 



After an enumeration of similar appearances, Macculloch f 

 has concluded with the following observations : " In these 

 cases, then, we have the stratified form as perfect as in the 

 most regular beds of secondary rocks, produced by a species 

 of crystallisation, a tendency to decided forms, with the laws 

 and causes of which we are at least as well acquainted as we 

 are with the laws that determine the figure of a quartz crystal. 

 At present they are both equally inexplicable. There is no 

 farther difficulty in conceiving that a rock may constitute a 

 huge bed separable into horizontal laminae, as regular as the 

 strata of a mechanical deposit, than in conceiving that the 

 island of Staffa is separable in columnar masses, or the rock of 

 Devar into vertical laminae. It is true that we have not yet 

 produced any instance of continuous, horizontal, laminar con- 

 cretions, which are incontrovertibly not mechanical ; yet its 

 existence implies no chemical impossibility. That which 

 occurs on a small scale may occur on a large : the terms are 



* Geol. Trans, vol. ii. p. 429. f Idem, vol. v. p. 137. 



| Idem, vol. ii. p. 428. 



