Ch. VIII.] THE GRANITIC AND SCHISTOSE ROCKS. 147 



surface. These fragments and the granite do not pass into 

 each other, unless the manner in which they unite be called 

 a transition ; they are perfectly distinct, but as intimately 

 united as the alburnum of a tree with its wood : the termin- 

 ation of the one, and the beginning of the other, are seen 

 distinctly, but the mass is equally strong at the junction as 

 any where else."* 



In the mountains called Ben na vear, near Balahulish, the 

 schist which is traversed by the granite is often much indu- 

 rated, and approaches by various undefmable gradations to a 

 sort of hornblende-slate. Masses of a similar substance may 

 be found imbedded in the granite. Occasionally these masses 

 appear, on close examination, to be only irregular spots of 

 hornblende, such as occur not unfrequently in those granites 

 of which this mineral forms an ingredient. More often, how- 

 ever, their shape is perfectly defined, being laminae with trun- 

 cated edges : and in some places, this appearance of fracture 

 is so precise, that when two fragments occur together in the 

 granite, the imagination as easily replaces the separated parts, 

 as it does in the brecciated marbles or agates : nay, farther, the 

 fragments will be sometimes found to consist of an argillaceous 

 or slightly micaceous schist, maintaining this character with 

 scarcely a perceptible alteration, and sometimes only ap- 

 proaching to hornblende-schist at its exterior parts. It is 

 also worthy of remark, that these fragments sometimes exhibit, 

 at their edges, stripes of different colours arid degrees of hard- 

 ness, arising from the varying texture of the laminae which 

 compose them. These masses vary in size from an inch to a 

 foot and upwards ; but, whatever their size may be, they have 

 almost invariably parallel sides. 



At Loch Rannoch, the schist, which is imbedded in the 

 granite, is often composed of black shining mica. Towards 

 the junction of the fragment with the surrounding rock, it 

 generally contains crystals of hornblende. The fragments 



* Wernerian Trans., vol. ii. p. 384. 

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