114 KERRERA. GEOLOGY. 



beneath.* This schist is also found occupying some 

 of the hills in the interior, even at a considerable elevation ; 

 but is so covered with soil, and intermixed with other 

 hills of trap and conglomerate, that it is impossible to 

 conjecture the nature and extent of its disposition in those 

 places. On the shores however, although its regularity 

 is by no means so absolute as in the islands to the 

 southward, the general bearing of the elevated edges 

 of the beds is north-easterly or nearly so ; a direction 

 which will be found to correspond very accurately with 

 that of the strata in many of the isles to the southward. 

 The dip is also invariably the same as in those, or 

 easterly; the angle of elevation however, varying much 

 more than it does in any of the islands where trap 

 does not occur, and being never properly assignable. 

 Beds of a coarser slate are found alternating with the 

 finer clay slate, and possessing the well known characters 

 of graywacke ; an alternation which is also to be found 

 in the neighbouring islands of Seil and Luing. 



The character of the clay slate is identical with that 

 of Seii and of Eysdill so well known in commerce, 

 and it is therefore superfluous to describe it. That 

 of the graywacke slate is equally familiar ; I need only 

 say that it is of a fine texture and marked by scales 

 of mica interspersed among the laminae. At the points 

 of junction with the trap, whether overlying or in veins, 

 both these schists are generally harder than elsewhere ; 

 while they are at the same time contorted, and easily 

 broken into fragments less regular and much more minute 

 than at a distance from those places. The action of the 



* With respect to the accompanying map I must observe, that it does 

 not pretend to give a detail of the rocks, since that would, on any 

 admissible scale, be impossible, on account of their extreme irregularity 

 and minute admixture. It points out one or two of the most conspicuous 

 portions of the strata ; the overlying trap necessarily occupying the chief 

 parts of the surface. 



