354 ARRAN. GEOLOGY. SCHIST. 



The region occupied by this class of rocks has already 

 been pointed out in a general way, and may be deduced 

 from the coloured map ; although its limits cannot be 

 very accurately defined, from the imperfect nature of the 

 maps of Arran hitherto published. 



It would be superfluous to enumerate the places where 

 the schist occurs, or where its boundaries are visible ; as 

 the list would be merely a tiresome record of names, and 

 as, for want of a sufficient number of these, many places 

 must still pass unnoticed : it will be sufficient to indicate 

 the former in a general manner, and the latter where any 

 remarkable appearances are visible. 



The most extensive and continuous mass is to be seen 

 between Loch Ransa and the mouth of the lorsa. It 

 here occupies the whole shore, forming a continued 

 range, sometimes of rocks and low cliffs, at others of 

 more gentle declivities. It may be traced from the shore 

 up the sides of the hills, and along the courses of the 



ing, or, from his deducing conclusions from the examination of hand 

 specimens or detached rocks. Thus the term greenstone, appropriated 

 to a member of the trap family, has als been applied to certain varieties 

 of granite. Miner alogically considered, this is sufficiently correct; but 

 it is plain, that unless the geological connexions of these two far distant 

 families of rock be taken into the account, the greatest errors may arise. 

 The reader must long since have perceived, what perhaps ought 

 to have been distinctly specified at an earlier period, that the term 

 granite has been invariably reserved for that rock which occurs beneath 

 all the strata, and that of syenite for the substance of analogous cha- 

 racter which is found above them. In one point of view this distinc- 

 tion is incorrect, but the latter term having been often so used already 

 by geologists, it is to a certain degree justifiable ; while, by using 

 it in this manner invariably, all geological ambiguity is avoided. The 

 two distinct and separate grounds on which a nomenclature of rocks 

 ought to be founded for the distinct purposes required, are such, that it 

 is not easy to reconcile them; nor am I prepared to amend that which 

 has so long been a source of difficulty to those of greater experience and 

 knowledge. In the present state of things it is somewhat to be intel- 

 ligible; an object worth attaining by a small sacrifice of logical arrange- 

 ment. 



