Ch. XII.] NATURE OF STRATIFICATION. 235 



but comparative, and the works of nature are not to be limited 

 by a measure taken from our own confined dimensions." 



We might multiply authorities to show that the concre- 

 tionary structure of granite, and of other so-called igneous 

 rocks, " resembles strata so accurately, that a careful and 

 unprejudiced eye must be the geologist's guide in distinguish- 

 ing laminae from strata, a concretionary form from a real 

 stratification." It might, however, be presumed, that a pre- 

 judiced eye is requisite to draw a distinction between things 

 which appear to be perfectly identical. 



We have seen, then, that the layers of granitic rocks are as 

 regularly parallel as the primary strata, and the argument 

 might be pushed even farther ; for, as far as our experience 

 goes, the layers of granite are sometimes more continuously 

 regular than those of the slate, the latter being generally 

 more curved, and not unfrequently contorted. It has also 

 been stated, that granite has been observed to have a regular 

 bearing, as recorded by Weaver in Ireland, De la Beche in 

 Normandy, and Enys in Cornwall, a circumstance which 

 cannot always be detected in the primary slates. For instance, 

 " the stratification of gneiss," says Macculloch *, " is un- 

 questionable, however difficult it may sometimes be to deter- 

 mine its order, or even to perceive its existence. In Scotland, 

 where this rock abounds, the prevailing direction of the 

 primary strata is between the N. E. and the N.N.E.; and 

 while it conforms to this, when obvious, there are indications 

 in the bearing of the coast, the positions of the hills, or the 

 comparison of parts on a greater scale, which prove, that 

 even where most obscure, it follows the same leading line : it 

 is often, in fact, by this prevailing conformity alone, that the 

 stratified disposition of gneiss is perceptible." By the same 

 rule, the granite would probably be found to have claims to 

 a stratified structure, if such indications had been sought 

 after. And, if the granite should prove to have a particular 



* System of Geology, vol. ii. p. 142. 



