252 GNEISS 



the gneiss itself. Such parallel veins are some- 

 times mistaken for beds of stratified granite, 

 when of considerable dimensions, or when care 

 has not been taken to trace their real nature and 

 connections. 



The stratification of those masses of gneiss 

 which contain few granite veins, is commonly 

 very regular and discernible ; and this regularity 

 of stratification will be found chiefly to prevail 

 in the two varieties distinguished here by the 

 terms schistose, and laminar. 



The contortions of gneiss are often extremely 

 remarkable, and they occur on a very large, as 

 well as on a small scale. Where hornblende 

 schist alternates with the strata, they are ren- 

 dered very conspicuous by the contrast of colour 

 between the two rocks. In some rare instances, 

 a sudden change occurs in the position of the 

 laminae, as if the rock had been fractured, and 

 the parts reunited at an angle to each other. It 

 must be remarked, however, that the contortions 

 of gneiss are seldom so minute as to be com- 

 prised, like those of micaceous schist, within the 

 limits of a specimen. 



