Mr William Stevenson on the Origin of Granite. 169 



this view, and its composition also agrees with it. Abun- 

 dance of red porphyry may be seen under the hard, dark, 

 grey rock, which has been so termed, and which constitutes 

 the upper part of the mountain. The junction of these, 

 doubtless, exhibits many interesting appearances, which the 

 heavy talus of fragments and the thickly falling snow pre- 

 vented my seeing on the occasion of my visit. 



3. Morven. — The district opposite Port Appin, and lying 

 southward of Kingairloch, consists chiefly of granite, of 

 which there are many varieties. At the base of the moun- 

 tains, close upon the shore, the felspar predominates to the 

 almost entire exclusion of the other constituents. At a 

 greater altitude, the granite is more normal in its character, 

 but mica is, upon the whole, rather rare. The granites are 

 fissured in all directions, with no apparent regularity, but 

 lines running N.N.E. to S.S.W. are rather more frequent 

 than the others. 



4. Loch Etive. — On the shores of the loch, N.E. of 

 Bunawe, the base of Cruachan presents a most extraordinary 

 combination of stratified and unstratified rocks. The latter 

 consist of granites of every variety, — felspar porphyries, with 

 acicular crystals of hornblende ; compact felspar ; a hard, 

 dark-coloured rock, like that which forms the upper portion 

 of Ben Nevis, &c. &c. The strata consist of hornblendic, 

 chloritic, and quartzose schists, all metamorphic in the ex- 

 treme, nowhere seen in large quantity, but broken up and 

 imbedded in the granite. For a mile or two along the shore 

 the granite is full of such detached masses. The transition 

 from the latter to the former is in some instances gradual, 

 and in others abrupt ; but in every case the most complete 

 junction has been effected, hand specimens, showing the 

 welding (so to speak) of the two, being readily attainable. 

 The granite here appears to have been formed in the same 

 manner as that of Glencoe, viz., by the melting down of the 

 more fusible schists, through the agency of the molten fel- 

 spar ; the less fusible portions, or those which happened to 

 be involved in the cooler or exterior parts of the seething 

 mass, having been only partially melted on the outside. 

 Very little mica is seen either in the granites or schistose 



