Page:Transactions of the Geological Society, 1st series, vol. 2.djvu/411

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various parts of Scotland.

pink coloured quartz. I did not observe any foreign matters imbedded in the trap, except minute drusy veins of calcareous spar.

Such are the very limited observations, which an inspection unavoidably much hurried, enabled me to make on this part of the group. Although the general aspect of the other two islands would lead me to expect in them an identity of structure, yet they may afford differences worthy at further investigation.

Rum.

A stormy sea, a dangerous shore, want of harbours, a trackless country, and a scanty and wretched population, render it as difficult a task to reach this island as to examine it.

It forms one mountainous tract of rugged and barren aspect, and of considerable extent, although its highest mountains, which lie towards the west, do not appear to exceed two thousand feet in elevation. My observations were limited to the only two parts of the island which are tolerably practicable, Loch Skresort, and Scuirmore.

Loch Skresort forms a semicircular indented bay, from which the land shelves gradually upwards by a moderate acclivity, till it approaches the middle region of the mountains, from whence the further ascent is steep, rugged, and often precipitous to the very summits. These terminate in craggy and broken points, exhibiting abrupt faces, and piles of ruins. The rock which incloses the bay of Loch Skresort, is a reddish argillaceous sandstone, disposed in beds and elevated to a low angle, varying from ten to fifteen degrees, occasionally fractured, bent, and displaced. It appears to be the result of the decomposition of granite, since the argillaceous grains are often found to consist of felspar in a state of integrity,

Vol. II.3 e