S. Spean River.

G. S. Glen Spean.

L. Loch Laggan.
T. Loch Treig.

ing in a northeasterly direction, and some ten miles in length. Across the mouth of this valley, at right angles with it, runs the valley of Glen Spean, trending from east to west, Glen Roy thus opening directly at its southern extremity into Glen Spean. Around the walls of the Glen Roy valley run three terraces, one above the other, at different heights, like so many roads artificially cut in the sides of the valley, and indeed they go by the name of the "parallel roads." These three terraces, though in a less perfect state of preservation, are repeated for a short distance at exactly the same levels on the southern wall of the valley of Glen Spean, just opposite the opening of the Glen Roy valley; that is, they make the whole circuit of Glen Roy, stop abruptly, on both sides, at its southern extremity, and reappear again on the op

1, 2, 3. The three parallel roads.

posite wall of Glen Spean. I should add, however, that all three do not come to this sudden termination; for the lowest of these terraces turns eastward into the valley of Glen Spean, following the whole curve of the eastern half of the valley, while, of the two upper terraces, there is no trace whatever, nor is there any indication that either of the three ever existed in the western half of the valley. When I first visited the region, these phenomena had already been the subject of earnest discussion among English geologists. The commonly accepted explanation of the facts was that these terraces marked ancient sea-levels at a time when the ocean penetrated much farther into the interior, and Glen Roy and the adjoining valleys were as maxy fiords or estuaries. And though the present elevation of the locality made such an interpretation

improbable at first sight, the first or highest of the terraces being eleven hundred and forty-four feet above the present sealevel, the second eighty-two feet below the first, and the third and lowest two hundred and twelve feet below the second, or eight hundred odd feet above the level of the sea, it was thought that the oscillations of the land, its alternate

Prepossessed as I was with the idea of glacial agency in times anterior to ours, these phenomena appeared to me under nations which may render my views of the parallel roads more intelligible, not to interrupt again the exposition with details. It would be desirable, however, that the reader should first make himself thoroughly familiar with the localities concerned, before proceed

the modern results of geology to have been so great and so frequent, might account even for so remarkable a change. There are, however, other objections to this theory not so easily explained away. There are no traces of organic life upon these terraces. If they were ancient sea - beaches, we should expect to find upon them the remains of marine animals, shells, crustacea, and the like. All the explanations given to lessen the significance of this absence of organic remains are futile. Again, why should the lower terrace alone be continued into the eastern end of the valley of Glen Spean, while there are no terraces at all in its western part, since both must have been as fully open to the sea as Glen Roy valley itself? This seemed the more inexplicable since all the terraces exist on the valley-wall opposite the outlet of Glen Roy, showing that this sheet of water, wherever it came from, filled the valley itself and the space between it and the southern wall of Glen Spean, but failed to spread, on either side of that space, into the eastern and western extension of Glen Spean. It is evident, that, at the time the water filled Glen Roy, some obstruction blocked the valley of Glen Spean, both to the east and west, leaving, however, that space in the centre free into which Glen Roy opens, while, by the time the water had sunk to the level of the lowest terrace, one of these barriers, that to the east, must have been removed, for the lowest terrace, as I have said, is continuous throughout the eastern part of Glen Spean.*

Having enumerated the characteristic features of the glacial phenomena in the preceding pages, I throw into this note some expla

that, in the wood-cut opposite, G. R. indicates the valley of Glen Roy, with the three parallel roads marked 1, 2, 3. Glen Spean is designated by G. S., and the river flowing at its bottom by S. Loch Laggan, out of which the River Spean rises, is marked . G. indicates Glen Gloy, a little valley to the northwest of Glen Roy, with a single terrace. Loch Treig is designated by T., Loch Lochy by L. O., Loch Arkeig by A., and Moeldhu Hill by M., while E. indicates Loch Eil. The Great Glen of Scotland, through which the Caledonian Canal runs, extends in the direction of L. O. and E. The position of Ben Nevis is designated by N. The dotted area betwen N. and M. marks the place occupied by the great glacier of Ben Nevis, when it extended as far as Moeldhu; while the close continuous lines in front of Loch Treig indicate the direction of the glacial scratches left across Glen Spean by the glacier of Loch Treig, when it extended as far as the eastern termination of the two upper terraces. It ought to be remembered, in this connection, that the bottom of the valley of the Spean, as well as that of Glen Roy, is occupied by loose materials, partly drift, that is, materials acted upon by glaciers, and partly decomposed fragments of rocks brought down by the torrents, greatly impeding the observation of the polished surfaces. The river-bed is cut through this deposit, and here and there through the underlying rock. Besides the parallel roads, there are also peculiar accu

mulations of loose materials in Glen Roy and Glen Spean, more particularly connected with the lowest terrace, which Mr. Darwin and Pro

fessor Jamieson have shown to be little deltas formed during the existence of the lake of Glen Roy at the bottom of the gullies intersecting the shelves of the upper roads. The outlet for the water at the period during which the second terrace was formed, not known when I visited Glen Roy, has been discovered by Mr. MilneHolme, and also observed by Professor Jamieson. During the formation of the upper terrace, the waters escaped through the westernmost tributary of the River Spey, in the direction of the northeast corner of the woodcut, and during that of the lowest terrace, at the eastern end of Loch Laggan, also through

a new aspect. I found the bottom of Glen Spean so worn by glacial action as to leave no doubt in my mind that it must have been the bed of a great glacier, and Dr. Buckland fully concurred with me in this impression. Indeed, the face of the country throughout that region presents not only the glacier - marks in great perfection, but other evidences of the ancient presence of glaciers. There are moraines at the lower end of Glen Spean, remodelled, it is true, by the action of currents, but still retaining enough of their ancient character to be easily recognized; and some of the finest examples of the roches moutonnées I have seen in Scotland are to be found at the entrance of the valley of Loch Treig, a lateral valley opening into Glen Spean on its southern side, and, as we shall see hereafter, intimately connected with the history of the parallel roads of Glen Roy. These roches moutonnées may very fairly be compared with those of the Grimsel, and exhibit all the characteristic features of the Alpine ones. One of them, lying on the western side of the valley where it opens into Glen Spean, is crossed by a trap-dike. The general surface of the hill, consisting of rather soft mica, has been slightly worn down by atmospheric agencies, so that the dike stands out some three-quarters of an inch above it. On the dike, however, the glacier-marks extend for its whole length in great perfection, while they have entirely disappeared from the surrounding surfaces, so as to leave the dike thus standing out in full relief. This is an instructive case, showing how little disintegration has gone on since the driftperiod. All the currents that have swept

the valley of the Spey. The state of preservation of the parallel roads is such as to prove that no disturbance of any importance can have taken place in the country since they were formed. Far from believing, therefore, that these remarkable shelves are ancient seabeaches, I am prepared to maintain, that, had the area occupied by them been submerged only for a few days, under an ocean rising and falling for several feet with every tide, no vestige would have been left of their former exist

ence.

over it, all the rains that have beaten upon it, have not worn away one inch from the original surface of the hill. I have observed many other roches moutonnées in Scotland, especially about the neighborhood of Loch Awe, Loch Fyne, and Loch Etive. In fact, they may be found in almost all the glens of Scotland, in the lake-region of England, and in the valleys of Wales and Ireland.

Following the glacial indications wherever we could find them in the country about Glen Roy, it became evident to me that the whole western range of the Grampian Hills had once been a great centre of glaciers, that they had come down toward Glen Spean through all the valleys on the mountain-slopes to the north and south of it, so that this valley had become, as it were, the great drainage-bed for the masses of ice thus poured into it laterally, and moving down the valley from east to west as one immense glacier. It is natural to suppose, that, at the breaking-up of the great sheet of ice which, if my view of the case is correct, must have covered the whole country at this time, the ice would yield more readily in a valley like that of Glen Roy, lying open to the south and receiving the full force of the sun, than in those on the opposite side of Glen Spean, opening to the north. At all events, it is evident that at some time posterior to this universal glacial period, when the ice began to retreat, Glen Roy became the basin of a glacial lake such as we now find in the Alps of Switzerland, where occasionally a closed valley becomes a trough, as it were, into which the water from the surrounding hills is drained. In such a lake no animals are found, such as exist in any other sheet of fresh water, and this would account. for the absence of any organic remains on the terraces of Glen Roy. But at first sight it seemed that this theory was open in one respect to the same objection as the other. What prevented this sheet of water from spreading east and west in Glen Spean? If it not only filled Glen Roy, but extended to the

Glen Roy and the central part of Glen Spean.

Evidently the glacier descending from Loch Treig was the first to yield, for, by the time the Glen Roy lake had sunk to the level of the lowest terrace, the entrance to the eastern extension of the valley must have been free, otherwise the water could not have spread through out that basin as we find it did; but it would seem that by the time the western barrier, or the glacier from Ben Nevis, was removed, the sheet of water was too far reduced to have left permanent marks of its outflow into the Great Glen, except by disturbing and remodelling the large moraines of the older Glen Spean glacier. There are faint indications of other terraces in Glen Roy, even at a higher level than the uppermost parallel road, owing their origin probably to the short duration of a higher level of the glacier-lake, when the great general glacier had not yet been lowered to a more permanent level determined by a limited circumscription within the walls of the valleys. There are other terraces in neighboring valleys at still different levels, in Glen Gloy, for instance, where the one horizontal road was no doubt formed in consequence of the damming of the valley by a glacier from Loch Arkeig. Mr. Darwin has seen another in Glen Kinfillen, which I would explain by the presence of a glacier in the Great Glen, the marks of which are particularly distinct about the eastern end of Glen Garry.

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The evidence of the ancient presence of glaciers is no less striking in other parts of the Scotch Highlands. Between the southeastern range of the Grampian Hills, in Forfarshire and Perthshire, and the opposite ridge of Sidlaw Hills, stretches

occupying the lower, and therefore warmer, level gradually disappeared and retreated far away to levels where it could maintain itself against the effect of a returning milder climate, the opening spring of our era, as we may call it, the lateral glaciers, arising from the nearer high grounds, could extend across the valleys, but not before.

the broad valley of Strathmore. At the time when Glen Spean received the masses of ice from the slopes of the western Grampian range, the glaciers descended from the valleys on the southern slope of the southeastern range and from those on the northern slope of Sidlaw Hills into the capacious bed of the valley which divides them. The glacial phenomena of this region present a striking resemblance in their general relations to those of the Alps and the Jura. The Grampian range on the northern side of Strathmore valley occupies the same position in reference to that of the Sidlaw Hills opposite, as does the range of the Alps to that of the Jura, while the intervening valley may be compared to the plain of Switzerland. As from the Bernese Oberland and from the valleys of the Reuss and Limmath gigantic glaciers came down and stretched across the plain of Switzerland to the Jura, scattering their erratic boulders over its summit and upon its slopes at the time of their greater extension, and, as they withdrew into the higher Alpine valleys, leaving them along their retreating track at the foot of the Jura and over the whole plain, so did the glaciers from Glen Prossen and parallel valleys on the Grampian Mountains extend across the valley of Strathmore, dropping their boulders not only on the slopes and along the base of the Sidlaw Hills, but scattering them in their retreat throughout the valley, until they were themselves reduced to isolated glaciers in the higher valleys. At the same time other glaciers came down from the heights of Schihallion on the west, and, descending through the valley of the Tay, joined the great masses of ice in the valley of Strathmore, thus combining with the eastern ice-field, just as the glacier from Mont Blanc and the valley of the Rhone formerly combined in the western part of Switzerland with those of the Bernese Oberland. The relations are identical, though the geographical position is reversed, - the higher range, or the Grampian Hills, lying to