170 



CHAP. XXVIII. 



Hornblende Schist. Actlnolite Schist. 



THE term Hornblende schist implies a familiar strati- 

 fied rock, of which it is a sufficient definition to say y 

 that it consists of hornblende, alone, or intermixed with 

 felspar, common, or compact; while generally, if not 

 invariably, schistose. Thus it may resemble the green- 

 stone of Trap, in specimens; while the chlorite series 

 just described contains some compact beds of it, often 

 remarkable for a prismatic structure, and thus capable 

 of deceiving even a good observer. But in every other 

 case, nothing but extreme ignorance or prejudice can 

 confound hornblende schist with an unstratified rock: 

 while the terms primitive greenstone and greenstone 

 slate, here suppressed, have produced utter confusion, 

 in this case, in the hands of those \vlio have so widely 

 perverted all geological philosophy : confounding, not 

 merely the schistose concretionary traps with this rock, 

 but all the traps of apparently antient associations, 

 with a stratified substance. 



Hornblende schist is so rarely found, in this country 

 at least, independent, and occupying a distinct place, 

 that little can be said respecting its great external fea- 

 tures. The only example which has occurred to me, 

 is the mountain Ben Lair in Rossshire, which consists 

 almost entirely of this substance, surrounded by gneiss. 

 It rises to the height of 3000 feet or upwards ; dis- 

 playing a very rugged and picturesque surface, with 

 extensive faces of bare rock. In all other situations, 

 hornblende schist either forms a portion of the great 

 mass of gneiss, or alternates with the other primary 

 schists; so that the general aspect of the country is 

 determined by a variety of concurring circumstances. 



Like the other primary strata, it occurs in distinct 



