Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/127



By J. M.D. F.L.S. President of the Geological Society, Chemist to the Ordnance, Lecturer on Chemistry at the Royal Military Academy, and Geologist to the Trigonometrical Survey.

HE geological history of this mountain being, as far as I know, unrecorded, I shall relate the few observations which I made on it, as they are sufficiently numerous to form at least a basis for future and more accurate investigation.

It is evident to any eye in approaching through the vales of Glenorchy or Glenara to the head of Loch Awe, that the nature of the country has changed. The rugged forms and rocky faces characterizing those hills of mica slate which bound Loch Lomond, Loch Long, Loch Fyne, or Strath Fillan, have disappeared; the mountains assume a more uniform flowing line, their sides are more completely covered with herbage, and exhibit fewer denuded rocks; their summits are less serrated, and are almost the only parts which exhibit the naked rock, while at the same time they are strewed with heaps of fragments, a character from which the hills of mica slate are almost always free. On approaching nearer to their bases, the red colour of the fragments which have fallen down from their sides, and the rounded pebbles of granite and porphyry which are met with in the beds of the torrents, give the mineralogist pretty plain intimation of the causes of this change of feature.