The valley of the Spean, and that of the western branch of Loch Eil, may be considered as opening together into the great C.Ileclonian valley by one common wide mouth, while the southern branch of Loch Eil lies in a valley comparatively narrow, formed by the skirts of Ben Nevis on one side, and the hills of Ardgowan on the other. A valley of a dead level extends to the head of Loch Eil ; and being little higher than the loch, it is of course ele vated but a lew feet above the sea, of which this water forms a branch. From the head of this valley a gentle rise conducts to Loch Shiel, a fresh water lake, which oc cupies a narrow prolonged valley that at length descends by a gentle declivity towards the sea at Loch Moidart. As the lowest of the lines of Glen Roy is 976 feet above Loch Eil, there can be no doubt that Loch Shiel is far in ferior to this, though its exact height is unknown. Con sidering these circumstances, therefore, if, in the present state of the country, water were raised to the level of the lines of Glen Roy, it would communicate with the sea at Loch Moidart, as well as at Loch Eil and the Murray Frith.
In returning now to the head or eastern communica tion of Glen Roy and Glen Spean, we shall first notice the former, where we before omitted any thing essential to these general views. That line which occurs in the up per part of in glen, we consider to be the same as the uppermost m Glen Roy. The author whom we formerly mentioned, Sir Thomas Dick Lauder, imagines it is the second ; nor do we pretend to decide on what is, perhaps, not very material. However that be, it is some feet elevated above the source of the Spey, which, as we have seen, forms the summit level for the eastern and western waters ; so that if water were now accumulated to the height of this line, it would also flow eastward, yet only to a very small depth.
The eastern outlet of Loch Laggan was already no ticed. The barrier of low rocks, and a plain of nearly four miles in length, separate it here from the valley of the Spey, and this plain conducts a sluggish stream into that river at a point about ten miles from its source. The observations formerly made respecting the small differ ences of elevation of this barrier above the line that sur rounds Loch Laggan, and which is the lowest of those in Glen Roy, show, that if water were now accumulated in Loch Laggan to a height much greater than that of the line that attends the Spean, it would tend to flow out at the eastern as well as the western extremity. If accumu lated to the same height as that in which it is supposed to have stood in Glen Roy, it would have an equal tendency that way, nearly from the highest to the lowest line, or for a vertical space or depth of near 390 feet. Thus its
issue in this quarter, if all these valleys once communicat ed, would be far more complete, supposing it had taken place at all, than by the level of the source of the Spey.
Such are the communications which these glens have with the surrounding country, and through that with the sea. They are of importance in investigating the causes of the phenomena under review; nor could the important geological consequences that may be deduced from them have been discovered or explained without considering these extended connections. We may now here terminate this minute description—a description justified as well by the singularity and extraordinary nature of the facts, as by the difficulty of apprehending all their relations and de pendencies without such details. We shall, therefore, proceed to examine the several theories that have been brought forward on this subject; giving to some of theni an attention which they do not merit on account of their probability or ingenuity, but which will render the general subject more intelligible, and place the geological parts of this question in a more satisfactory point of view.
We already gave an authentic account of this theory from the best authority, that of a resident minister, Mr. Ross. The arguments used to prove either that they were made by Fingal and his followers, or by certain kings of Scotland who lived in Inverlochy Castle, are of two kinds. They are derived from supposed traditions, and also from certain physical or supposed artificial appearances in the Parallel Roads themselves.
It can scarcely now be necessary to return to the much• discussed question respecting the age of Fingal. But whatever opinion we entertain on this subject, we cannot sec that the least stress is to be laid on those traditions which give names to the hills derived either from the great hero himself, from his friends, or from his dogs. All over the Highlands this fashion is universal, as we formerly re marked. In Glenco, in Glen Lyon, in Morven, Mull, Staffa, Sky, Glen Almond, Arran, and in many other places, even as far as the Carron, we find the same names bestowed on similar objects, and the same traditions; while the very tombs of many of these warriors are point ed out in so many places that they must have possessed the property of ubiquity in death as well as in life. Such traditions know not where to stop, and can never be con sidered as an argument for any theory of the parallel roads.