Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/350

 Fortunately it is not material with regard to the general results that must follow from considering the phenomena of Glen Roy, since these will be still nearly the same although these glens had not existed. The glen of Loch Eil however, which I have examined, requires a more detailed description, as it is probably implicated in the consequences which will follow from one of the theories that must be had recourse to in explaining the appearances of Glen Roy.

The valley of the Spean and that of the western branch of Loch Eil may be considered as opening into the great Caledonian valley by a common wide mouth; while the southern bend of Loch Eil lies in a valley comparatively narrow, formed by the skirts of Ben Nevis on one side, and the hills of Ardgowar on the other. It is necessary to keep this circumstance in mind till the probable causes of the lines in Glen Roy are brought under review. A valley of a dead level extends to the head of Loch Eil, which being little higher than the loch is of course elevated but a few feet above the sea, of which its water forms a branch. From the head of this loch another gentle rise conducts to the head of Loch Shiel, a fresh water lake, which occupying a narrow prolonged valley, at length descends by a gentle declivity into the sea at Loch Moidart. I cannot give the elevation of Loch Shiel, which is nearly the highest point of this level, but from an estimate formed on the ground, which at any rate cannot be so far in error as to affect the question, conclude it to be inferior to all the lines of Glen Roy, the lowest of these being 976 feet above Loch Eil. Water therefore, if we could now imagine it raised to the levels of the lines of Glen Roy, would run to the sea at Loch Moidart, as well as at Loch Eil, and at the Moray Firth.

Returning to the head or eastern communication of Glen Roy,