Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/349

 Spean, as must have already been remarked, like that of Glen Roy, has the same direct and present communication by means of the Lochy with the western sea.

The opening of Glen Gloy is narrow, but its communication at Lowbridge with the long valley now described, is at a point somewhat higher in elevation than that at which Glen Spean enters, since its water falls into Loch Lochy, the source of the river of the same name.

Tracing therefore the course of this valley, into which Glen Roy and Glen Gloy open, we find it communicating with both seas. Its highest level is at Loch Oich, the point from whence the waters decline in two directions, and this elevation is ninety feet above that of the sea at Loch Eil. Besides the waters issuing from Glen Roy and Glen Gloy, it receives at various points to the south-westward of its summit level, the streams which issue from Loch Eil, Loch Arkeig, and numerous smaller glens, while on the north-eastern slope it is the receptacle of the waters of Loch Garry, Glen Morrison, Fyers, Glen Urquhart, and others of less note. Hence it appears that its upper level is inferior by 886 feet to the lowest line of Glen Roy, and by 1180 feet to the uppermost, the height of the upper line of Glen Roy being found from barometrical measurement to be 1262 feet above the level of the western sea. Examining now the glens which communicate laterally with this great valley, we shall find that they are all situated on the western side. They are Glen Morrison, Glen Urquhart, Glen Garry, the glen of Loch Arkeig, and that of Loch Eil.

From want of time for so laborious an undertaking, I am unable to describe either the disposition or the elevations of the four first of these branches, but have reason to think that they all rise at their western ends to levels higher than those of the lines in Glen Roy.