MICACEOUS SCHIST, 267 



MICACEOUS SCHIST. 



THE uncertain position of micaceous schist 

 with respect to the other primary rocks, has al- 

 ready been stated as far as is necessary for the 

 objects of this work. Like gneiss, it generally 

 forms extensive tracts of country and ranges of 

 high mountains, but is sometimes also found oc- 

 cupying very small spaces, , in alternation with 

 other primary strata. The consecutive beds 

 therefore, constitute, in some cases, masses of 

 great thickness; while, in others, they may be 

 found not exceeding a few feet in dimensions, 

 and forming a very unimportant part of some 

 series composed principally of other substances. 

 In gneiss, as already shewn, it sometimes occurs 

 in beds of very inferior dimensions ; and, in the 

 same manner, it is found accompanying quartz 

 rock, with which it is often very extensively as- 

 sociated, as will be more particularly detailed 

 hereafter. 



