160 MICACEOUS SCHIST. 



deduced its relations to the primary strata : but I 

 must also add, that it is often immediately succeeded 

 by the secondary, as in Canty re. 



Micaceous schist, like all the primary strata, is dis- 

 posed in beds ; often, however, rendered obscure by 

 their great thickness, by the want of distinct seams 

 of division, and by the irregularities and contortions 

 to which this rock is subject. When it enters in 

 small quantity among other rocks, the beds are, how- 

 ever, always very distinct ; and, in the Chlorite series, 

 extremely regular and even. Its interior structure is 

 various ; sometimes consisting of straight laminae, 

 rigidly parallel, and in one plane ; while at others, the 

 general parallelism of the laminae is maintained, but 

 their thickness varies, so as to affect this appearance 

 of regularity. In other cases again, these are minutely, 

 or even largely undulated, still preserving the disposi- 

 tion in a plane ; until, by at length increasing in size, 

 they also lose that general conformity to an imaginary 

 plane, finally assuming the most capricious contor- 

 tions ; no longer bending round any given straight 

 line or set of parallel lines, but presenting curvatures 

 in every possible direction. From the frequent diffi- 

 culty of discovering the true position and limits"of the 

 bed, it is thus sometimes impossible to know whether 

 these curvatures involve the whole stratum, or whether 

 they affect the interior structure only. The lesser un- 

 dulations and curvatures, are, evidently, often indepen- 

 dent of any corresponding change in the evenness of 

 the bed ; and the same probably often holds true of 

 the more complicated, since they do not seem to per- 

 vade the whole mass, but rather to occupy particular 

 spots among the neighbouring and less disturbed la- 

 minae. In some of these cases, it is very difficult to 

 trace the stratified disposition; and such a state of 



