In speaking of the changes which the face of the country has undergone in the lapse of geological time, I can only advert to those that have occurred within the most recent period—that during which the superficial deposits, the till, the gravel, the sand, the travelled boulders, the soil, and the moss were produced, and came to occupy their present positions. If we should seek to go farther back than this in quest of information, we should find no resting place, no record to read till we had descended to the very earliest ages; for we have in this part of Scotland no intervening deposits between the newest and the oldest. The meaning of this fact probably, though not certainly, is that never,

"Since Britain first at Heaven's command
Arose from out the azure main,"

have these parts been for any considerable length of time, if at all, under the waters of the ocean. Whatever place therefore we may take as a people in the history of our race, the country we inhabit will bear comparison in respect of age with any other on the face of the earth; for in these northern highlands we tread the oldest dry land of the old old world.

But leaving the long geological cycles that have passed since the first appearance of the crystalline rocks on the dry crust of the earth, we shall begin our short history with the period that immediately preceded the deposition of the till that now mostly overlies them.

It was a warm period—a period when the country was clothed with immense forests, in which huge wild beasts roamed, devouring the rank vegetation or preying upon each other. The lion and hyaena were common enough in Scotland, along with the rhinoceros and hippopotamus in England; while others of a more ancient type, such as the mastodon, and megatherium {the great wild beast), lingered around us on the continent—or what we now call the continent, for it is probable that Britain then formed a part of it.

Just as that period was drawing to a close, the valley of the Dee presented an appearance very different from what it does now. Instead of enclosing a clear continuous stream that collects its principal waters amongst the mountains of Braemar, and flows without interruption over its pebbly or rocky bed to the sea, the valley was then broken up into a series of long, narrow troughs, containing lakes, from the one to the other of which the river leaped over the intervening barriers in grand waterfalls, or rushed through narrow gorges in wild cataracts, of which we have still small examples at Fotarch and the linn of Dee. What is now the spur of Culblean was then an intersecting ridge rising on the south into the Bellamore Crag, behind Headinsch. For long ages the lowest point in this rocky barrier was the Slock behind Mr. Gaskell's House, at Cambus o' May, and through this gorge the river, for a great length of time, found its escape from the lake above to the lake below. The polished water worn rocks may still be seen at some points on the north side of the gorge, which has now, however, been mostly filled up with glacial deposits. The immense quantity of river gravel that still remains in flats and mounds at this point is another proof that here the stream emptied itself into the lake. The lighter of these materials—the fine sand, the clay, and the mud—would be earned far into the lake, and sink to the bottom at a long distance off; but the heavier, the gravel and stone, would be deposited as soon as they entered the still water. These would block up the mouth of the river, causing it to diverge by turns to the north and to the south, thus spreading the debris it brought down to a considerable distance on either hand, and, though much altered by after agencies, this is just what we find along what was then the margin of the lake.

The tertiary period, to which we are now referring, was not only a warm period, it was in Scotland also one of great earthquakes. There was even a chain of volcanoes on the west coast, pouring out, in their frequent eruptions, streams of lava, and altering the whole face of the country. It is quite possible that during some of these earthquakes, a deeper fissure might have been formed in the ridge of Culblean, to the south of the present channel of the river; and the water might have escaped through it sometime before the close of this period. I have been led to form this conjecture from finding, on an examination of the deposits brought to light by the extensive works carried out by Mr. Gaskell around his mansion, every nook and crevice in the rocks filled with fine water-wrought sand, evidently carried into these corners by the eddying of the waters. There were sufficient causes in operation during the succeeding epoch to produce this motion in the waters of the lake, and it may have been due to them; but certainly the shifting of the outlet in the manner supposed would have given rise to it, and produced the deposits observed.

At all events, what is now the moor of Dinnet and district of Kinnord formed the largest of the whole series of lakes that then lay in the line of the valley of the Dee. It was produced by a rocky barrier stretching across the valley near Boghead, and uniting the ridge of Bellrory on the south, with the Mulloch range on the north. Towards the close of the tertiary period the passage of the river over this ridge was about 130 feet above its present bed. The lake formed by this barrier terminated to the west in a fine bay, the shores of which swept round behind the farm of Ballaterich, and stretched northward with many a headland and creek, into the district of Cromar, as far at least as the mansion-house of Blelack. At a former period it had been of much greater extent; but the barrier had gradually got worn down by the action of the water, till towards the close of the tertiary age it had shrunk to something like the above dimensions, i.e., about five miles in length from north to south, and three miles of average breadth. Large as it was, it contained but two small islands, situated about a mile-and-a-half apart, near the middle and deepest portion. The roots of these still remain in the rocky eminences of the two Ords that bound Loch Kinnord, the one on the north and the other on the south.

Slowly diminishing in size, this lake had continued for countless ages to fill the valley; but a change was now drawing on that was greatly to alter the features of the landscape. From some cause, which has not yet been satisfactorily explained, the climate began to change, and that not for the better. Year by year, or I should rather say, century by century, for the change was slow in its progress, the winter cold became more severe, and the summer heat shorter. The hills, which were then higher and steeper than they are now, began to wear snowy mantles all the year round; and cold tongues of ice were thrust out from the corries of perpetual snow, and descended a long way down into the valleys beneath. All but the hardiest animals deserted the country. The old forests decayed; and nothing but a scanty arctic vegetation lurked behind, and that only on sheltered and sunny spots in the low grounds. Still, the winter cold went on increasing in severity till every mountain was covered with perpetual snow, and every valley enclosed its glacier. These glaciers stript the country of its former soil, ground it into a fine powder, and, working it up into a soft clay, dropped into its mass the boulders they had torn from the overhanging rocks, and rolled them along often to a great distance. In this manner was formed underneath the glaciers that extensive deposit of stiff clay studded with stones of all sizes, but mostly somewhat water-rolled, or rather ice-worn, to which geologists give the name of till. It generally contained a large quantity of iron, obtained from the decomposed vegetation of the previous era. This element furnished a cement which, when the deposit settled, bound the clay together somewhat like an asphalted floor, and gave rise to the subsoil which agriculturists dread as the most barren and intractable they have to deal with. In this part of the country they call it a 'pan, which I do not think by any means an inappropriate term.

When the glaciers, descending from the heights of Morven and Culblean, reached the. waters of the lake below, they broke off, and floated about as little icebergs, depositing their burdens of stones and gravel here and there over its bottom. Of course many of them would get stranded near the two islands ; and it is just there that we find the greatest accumulation of surface-borne stones and rocky fragments. All this went on for many ages, till the whole country was covered with ice and snow—ice-capped, in short, as much of Greenland now is—and the glaciers actually reached the sea.

The great glacier that occupied the valley of the Dee was probably at that time not less than a thousand feet thick.

When this had lasted for a period of indeterminable duration, the climate began to get milder; less snow fell in winter, and the summer heat had greater power to melt it. The great ice age was on the wane. But the whole period of its decline was one of fearful floods. The soft snows on the surface melted first; and the old valleys being blocked up with hard glacial ice, the streams reeled along in directions often the very reverse of what they now take. And though their courses were over the ice, they carried along quite as much sand and stones as if they had run in channels of ordinary soil; for these decaying glaciers were covered to a great depth with the rock debris that had been accumulating on them for ages. They are sometimes found in this condition still among the Himalayas, so that travellers can scarcely tell whether they be walking on firm ground or on de&ra-covered glaciers. It is this circumstance that has mostly given rise to the difficulty of understanding how mounds of water-borne materials could have been collected in the unlikely situations in which they occur.

At length all the snow and smaller glaciers had shrunk back to the higher hills, but the great glaciers still continued, though in diminished bulk, to fill the main valleys, and obstruct the natural drainage of the country. The Dee glacier, hundreds of feet in thickness, formed a dam at Dinnet so deep that the lake behind it stretched back to the skirts of Morven. Meantime the wear and tear which the face of nature was undergoing was not less during the decay than during the prevalence of the ice age, though the agent and the kind of work done were different At first it was rivers of ice, now it was headlong floods of water; and between them they produced such a transformation of hill and dale, that if one could have seen the country before and after, he could scarcely have known it to be the same. The very hills were different. In most instances their summits were flattened, their sides sloped, and their corries changed They were, indeed, only the weather-beaten stumps of what they had once been; while the old lakes that had lain in the valleys below were almost all gone, and their beds occupied by unsightly wastes of water-rolled stones and sand, as bare as fresh river stanners. This, at least, was the result in the case of the Moor of Dinnet Remnants of the former lake, it is true, still survived in straggling patches. But the great ice river had worn away the rocky barrier, and only in the deeper depressions of the old bottom, as at Kinnord, Davan, and the Ordie Moss, was there any water remaining that could properly be called a lake.

Kinnord was a most unlovely place then, with the Dee almost on a level with its lake, coursing in scattered streams round shingly islands here and there. At last, however, it gathered its waters together, and by slow degrees scooped out for itself its present channel. While it was so occupied, and it must have taken a long time to do it, vegetation, under the improving climate, was busy clothing the face of nature. The shallower pools were becoming swamps and morasses; every plant was taking root in its suitable habitat, and every tree in its friendly soil The animal tribes, also, to whose habits the country and climate were favourable, were gradually finding their way back into the unoccupied territory!

When things had arrived at this pass, the Geological record may be said to have closed; and we next open the Pre-historic Volume.