270 MICACEOUS SCHIST. 



force, only separates the laminae, or produces a 

 very irregular transverse surface. 



It is yet unsettled whether, in all cases, the 

 laminar structure of micaceous schist is parallel 

 to the plane of stratification, or whether it may 

 not, as in argillaceous schist, be sometimes at 

 angles to that. But if the minute undulations 

 be excepted, no observations as yet prove the 

 latter; and, from the analogy of gneiss, where 

 they appear to be always coincident, it is probable 

 that the former is true. 



Micaceous schist, as it differs from gneiss in 

 composition, differs only from that rock in not 

 containing granite veins as a frequent feature. 

 Wherever these are found, they occur only, as in 

 other rocks, where it is in contact with granite ; 

 and the veins are then limited to a small distance 

 from the mass of that substance ; being ramifica- 

 tions from some larger intruding vein, or from 

 the principal rock, and, commonly, easy to trace. 

 But it is subject to be much penetrated by quartz 

 veins, either transverse or parallel to the laminae ; 

 and, where these are contorted, the veins follow 

 those contortions. 



