120 Dr. Mac Culloch's observations 



terest, while it naturally leads the geologist to inquire into the state 

 of things under which so remarkable a dismemberment of these strata 

 . has taken place. 



In quitting this part of the skirt of Cruachan it is necessary 

 either to rise to a considerable elevation, crossing above the woods 

 of Inverawe, or to avoid it altogether and make a circuit by Bunawe. 

 We then reach the shore of Loch Etive, and may continue our ob- 

 servations on the base of the mountain. As we ascend to cross 

 the foot of the hill granite appears exclusively, generally in the 

 shape of loose blocks accompanied by similar pieces of porphyry, 

 but sometimes in situ. On reaching the shore beyond Bunawe the 

 appearances become more interesting. The junction of the granite 

 with the schistus is here clearly seen. Large veins may be observed 

 proceeding from the great mass of the mountain, and ramifying into 

 innumerable small divisions penetrating and traversing the schistus 

 in every direction. No where can this appearance which has excited 

 so much attention, be more distinctly perceived, and it is moreover 

 attended here by some interesting circumstances, which as far as I 

 have observed do not occur in the junctions at Loch Ranza, in Glen 

 Tilt, or at Locheil. Two distinct varieties of granite appear in this 

 place ; the one a granite according to the strictest acceptation of the 

 term, consisting of reddish felspar, quartz, and mica ; the other a 

 syenitic granite, or a compound of white felspar, mica, and horn- 

 blende. These are coexistent in every respect and seem to pass 

 into each other, while both of them ramify in a similar manner 

 through the schist, a sufficient proof, if any were wanting, of the 

 geological identity of these two rocks which have so improperly 

 been distinguished by the accidental presence or absence of the single 

 ingredient hornblende. Although the granite veins sometimes run 

 through the schist in a distinct form, just as they do in the junction 



