John MacCulloch

“ If by any causes of a nature similar to those which we see in daily action on the surface of the earth, it must have been by the flowing of rivers upon them. Thus the flow of the Ness and the Spey towards the sea, might have lowered the land in these directions to their present level, and thus the exit of Loch Shiel might have destroyed the barrier to the west; while the repeated failures of the supposed barrier at the mouth of the Lochy had in the mean time produced the complete drainage of Glen Roy and Glen Gloy, and with the exception of Loch Laggan, that of the Spean. ”

“ It must equally be remembered, that if Glen Roy was then open to the sea, and that its lines are to be considered as ancient sea shores, the ocean must have undergone three several depressions of level at long and apparently equal intervals of time, the last of which, it must be supposed, reduced it to its present state. On considering the elevation of the uppermost line, it is plain that the ocean must in this case have covered the greatest part of our island; to pass over the much larger tracts of the globe which must then also have been immersed under it. ”

“ Where the declivity is greatest, the shore is not only narrowest, but its inclination is the greatest; and vice versa, it is most level and of largest dimensions where that is least. The reader who will recall to mind the particular description of Glen Roy, will recognize all these features in the present state of the lines; and it is scarcely to be doubted, that if the sudden drainage of such a lake as I have here described could be effected, its sides would present the appearances which occur in that valley, as far at least as all the requisite conditions were present. ”

“ We must imagine the glen filled to the depth of its upper level with alluvial matter, and suppose that a wasting stream has held its course through it for a space of time so long as to remove the whole matter to its present depth, leaving the lines which are now marked on its sides, together with the terraces that are to be seen at its upper end, as memorials of its destroying force. This is the second hypothesis depending on the action of water which has been offered in explanation of the appearances in Glen Roy. ”

“ 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. ”

“ In as far as the mineralogical structure of the country is concerned in the description of the lines of Glen Roy, I have already noticed the principal facts in describing the nature of the alluvia which form the surfaces of the hills. I may however proceed to say, that the natural rock is not often visible on their faces, although it may be observed in most parts of the bed of the river. I have already briefly remarked that at the upper part of the valley it consists of a hard micaceous schist traversed by veins of red granite. ”

“ The appearance of the parallel roads is so extraordinary as to impress the imagination of the most unphilosophical, nay, even of the most incurious spectator. It is not therefore surprising that they should excite the admiration of the natives, in whom the progress of civilization has not yet extirpated those poetical feelings and that sense of the sublime, of which their literary relics still afford us proofs. ”

“ If then there was a current common to both these vallies, the communication must have been formed by the opening of Glen Gloy through the intervention of Loch Lochy. A stream of water must therefore have run from a point where it had either a free exit, or at least a wide space in which to diffuse itself, to one whence there was no exit, and with a velocity as great in the most difficult as in the most easy circumstances, since the lines of Glen Gloy, wherever they exist, are at least as deeply impressed as those of Glen Roy. ”

“ To those who, in considering the lines of Glen Roy as works of art, are inclined to cut this knot of difficult solution, and to repose in a tacit acquiescence on motives which they are unable to appreciate, and on a state of society and manners of which history affords us no information, the whole discussion may appear unnecessary. ”

“ It is not however inconceivable that the causes which are now, by the accumulation of alluvium, obliterating the existing lakes, should, under some variation of ground, have heaped a barrier in the course of a valley; and generated at one period a lake which they were afterwards destined to destroy, or which, accumulating strength by confinement, while the opposed barrier was undergoing a slow waste, should suddenly break its bounds and again desert the valley which it had been previously compelled to occupy. ”

“ Viewing them indeed in the most vague light as roads, even if we do not attempt to assign an object for them, they are either deficient in the qualities which a road requires, or they do not exhibit the marks by which it would be characterized, or lastly they are arranged in a manner so capricious as to render a motive for their disposition unfathomable. ”

“ Clay, gravel, and stones thus transported are deposited in banks which skirt the course of the torrent at the level of its highest elevation, often continuing to mark that course to future times, till a fresh flow of water rising to a higher level destroys them or substitutes higher banks in their places. A partial deluge is but a torrent on a greater scale, and we can therefore conceive this phenomenon extended in its magnitude and consequences, but producing a similar set of appearances. This cause has been supposed to have produced the lines of Glen Roy. ”

“ Now although the action of the present water flowing in that part of the bottom of Glen Roy which has the character of a strath, does actually produce the abrupt forms of the present terraces, it does not follow that this cause has acted throughout the whole valley. It would require a stretch of imagination beyond our power, to suppose that a successive action of water should have produced three lines, and these only (for the exceptions are much too trifling to affect the argument) at fixed intervals, through a space so large, without leaving their intermediate marks. ”

“ It is vain to inquire into the æra or history of the Fions, whether they existed at the time of Severus's expedition, or at a period prior to that, since rational antiquaries have given up the point in despair. Nor are the traditions concerning their connection with these roads, even if we admit their existence at some remote period, such as to demand any acquiescence in this conclusion. It is said that the hills of Glen Roy are named after the heroes or dogs of this favourite and poetical age ”

“ I must in the first place remark, that the causes here assigned for the appearances in Glen Roy are attended by consequences materially affecting the notions which have, with otherwise much appearance of reason, been entertained relating to the ancient state and posterior changes of the great Caledonian valley. It is conceived by many persons that Scotland was once entirely or partially divided in this place by the sea, the highest elevation of the present land being, as we have already seen, ninety feet. ”

“ If also we suppose that Glen Gloy was dammed by a barrier of its own, independently of that which occupied the common opening of Glen Roy and Glen Spean, we multiply our difficulties without any necessity. A continuous lake must therefore be supposed to have existed among the present vallies of the Roy, the Spean, the Gloy, and Loch Lochy, independently of that portion of Strathspey which I have described above. ”

“ Where the action of the river has been such as to cut its way, constantly deepening, through an alluvial plain, the surfaces of these terraces will be found level, and they assume an artificial appearance. In other cases their surfaces are irregular, and often, where the river encroaches near on the original hill, are gradually blended with it until they are lost in the general slope; the river forming a second and more abrupt one in the covering of alluvium which time or more active causes have accumulated on its face. ”

“ It follows yet, from a general view of these alluvia, that many of them are probably of a formation more ancient than the last great changes which produced the present state of the surface, if we consider the drainage of Glen Roy to appertain to those changes. But we are in danger of being bewildered in the views which open on us when we pursue the operations of Nature so far beyond the limits of our immediate observation. ”

“ The general equality of breadth which prevails among the lines is equally opposed to the notion of their being the remains of terraces; as it is impossible that such an equality should have been preserved amongst them. ”

“ It is by an attention to circumstances which at the first glance appear trivial, that abstruse truths are often discovered; and it is precisely where leading and obvious phenomena offer no clue to guide us, that a ray of light will often be thrown on the subject from appearances at first neglected. ”

“ I have attempted to keep clear of all speculations purely hypothetical, and wherever physical evidence and analogy have entirely failed, have rather chosen to leave the question in its natural obscurity than to involve it in more profound darkness by assigning imaginary causes. ”

“ The marks of three are then to be seen on the salient angle of a green hill on the left bank of the stream. As far as the eye can judge of their relative distances (for I was unable to measure them) they appear to correspond to those of Glen Roy: but the upper and lower one soon terminate, while the middle one is continued for some little way up the valley. On the right side of the stream, opposite to them, a very strongly marked line of considerable breadth occurs, extending up the valley for a long space beyond the reach of the eye, accompanied by an inferior one far less persistent. ”

“ But if we examine any one of these furrows we find that a portion of it, one half perhaps, and that of course the most ancient as the most superficial, bears the unwasted mark of the lines while the interior part, subject to a more modern destruction, exhibits no such impression. ”

“ On each side of a long, hollow, deep valley, bounded by dark and lofty mountains, and at a great elevation, three strong lines are traced, parallel to each other and to the horizon, the levels of the opposite ones coinciding precisely with each other. ”

“ Wherever the hill is formed of a soft alluvium they possess the greatest breadth, while, on the contrary, wherever the ground is rocky, they are scarcely to be traced. It is plain that they should, if they had been roads, have exhibited superior permanence in the most durable materials. ”