« PředchozíPokračovat »
Billow on endless billow: on through wood,
Shoot on their leafless boughs the sleetdrops chill,
O'er rugged hill, down sunless, marshy That on the hurrying crowds in freezing
Was won and lost, and thronged with Now tremble, men of blood-the judgment
AMONG the many forms of scenery which vary the surface of the earth, none fixes itself more firmly on the memory and the imagination than that of the hills and mountains. The aspect of the lower grounds is liable to constant change. We see the waves wearing down the shore, and the rivers ever and anon devastating the meadows. Man himself does much to transform the landscape: he ploughs up peat-mosses, cuts down forests, plants new woodlands along the hill-sides, covers the valleys with corn-fields and orchards, graves the country with lines of roadway, and builds his cottages, villages, sea-ports, and towns. But high above the din and stir of these changes, the great mountains rise before us with still the same forms of peak and crag that were familiar to our forefathers long centuries ago. Amid the fleeting outlines of the lowlands these alone seem to defy the hand of Time. And hence "the everlasting hills" and "ancient mountains" have ever been favourite emblems of permanence and grandeur.
Not that signs of revolution failed to be perceived in the early ages among the crags and valleys of the hills. There is an air of ruin and waste about these high grounds which no eye can miss. But the cleaving of their ravines, the scarping of their precipices, the opening of their valleys, and the strewing of their slopes with piles of loose rock, were looked upon vaguely as the complex result of the first grand upheaval of the mountains out of chaos.*
Sometimes, however, the traces of destruction were too marked
* This popular belief, which even yet, in spite of modern science, has not become extinct in this country, is well expressed by Milton:
"When God said,
Be gathered now, ye waters under Heaven,
Into the clouds! their tops ascend the sky :
Paradise Lost, book vil
to be assigned even by the popular mind to the first creation of all things. The hills looked as though, long after their birth, they had been rent in twain; the cliffs were shattered and broken, as if they too had suffered from a like catastrophe; the huge fragments of crag and mountain scattered over the declivities, or lying thickly in the valleys below, seemed all to tell of some conflict, later, indeed, than the making of the world, yet lost in an antiquity far beyond the records of man. To the influence of scenery of this kind on the mind of a people at once observant and imaginative, such legends as that of the Titans should in all likelihood be ascribed. It would be interesting to trace back these legends to their cradle, and to mark how much they owe to the character of the scenery amongst which they took their rise. Perhaps it would be found that the rugged outlines of the Bœotian hills had no small share in the framing of Hesiod's graphic story of that primeval warfare wherein the combatants fought with huge rocks, which, darkening the air as they flew, at last buried the discomfited Titans deep beneath the surface of the land. Nor would it be difficult to trace a close connection between the present scenery of our own country and some of the time-honoured traditionary stories of giants and hero-kings, warlocks and witches, or between the doings of the Scandinavian Hrimthursar, or FrostGiants, and the more characteristic features of the landscapes and climate of the north.
But apart from the region of fable and romance, it is impossible to wander among the glens and solitudes of a wild, mountainous tract, without feeling a certain vague awe, not merely on account of the magnitude or loneliness of the surrounding scenery, but from the mystery that seems to hang over its origin. The gentle undulations of a lowland landscape may never start in the mind a passing thought; but we are arrested at once by the stern, broken features of the hills, and cannot help asking ourselves how they came into being.
To such a question the natural answer is sought in vast primeval convulsions, that suddenly tossed up the mountains, rent open ravines and glens for the rivers, and unfolded wide valleys to
receive and remove the drainage of the country. There is an air at once of simplicity and of grandeur about this explanation, which has made it a favourite and popular one. It deals with that dream-land of conjecture and speculation lying far beyond the pathways of science, where one has no need of facts for either the foundation or superstructure of his theory. It thus requires no scientific knowledge or training; it can be appreciated by all, and may be applied to the history of a mountain-chain by one to whom the very name of geology is unknown. No man, indeed, who is aware of what has been ascertained of the history of the earth can hold this popular notion to the full; for it is now well known that the mountains are of many different ages,—that some of them were rent and worn down before others had begun to be, and that the rocks which form the present surface of the earth are the result of many successive ages of geological change.
To whatever source the origin of the existing configuration of the surface is to be traced, the result of the whole has been a system of the most nicely-adjusted symmetry. Hill and mountain, valley and glen, seem each as if made to fit in closely with its neighbours. One main office of land is to serve as a channel, in which a part of the water which rises from the sea into the clouds may find its way once more to the deep. The manner in which this task is accomplished, familiar and even common-place though it may be, can hardly be thoughtfully contemplated without wonder. From the high grounds the gathered rains and springs descend in hundreds and thousands of water-courses, which, from the tiniest runnel up to the ample river, are all arranged in the closest harmony with each other, and with the whole orderly system of which they form a part. This well-balanced symmetry cannot but have resulted from some general cause, acting uniformly throughout the land which it fashioned for its own ends.
The form of the valleys may vary indefinitely without disturbing the general symmetry. They may be wide, open, smooth, with gently shelving sides; or they may be only narrow gorges, in which the rivers toil between naked walls of rock. Merely from the map one cannot tell where the valleys are wide, and where
narrow. The most precipitous ravines fall easily into the general plan, and lie in the paths of the streams just as naturally and unconstrainedly as do the widest straths. Nor should we fail to remark that the ground-plan of the valleys, as defined on a map by the courses of the streams, is marked everywhere by the same great features, whether the region be one of mountains or low plains. If the map has no hill-shading, it may be impossible to tell which are the higher mountain ranges, and which the lower groups of hills and plains, so uniform is the disposition of the valleys and water-courses apart from relative height.
We have to inquire by what probable means this harmonious grouping of hill, and valley, and water-course was brought about.
Two explanations have been given. One calls in the aid of old terrestrial convulsions, and looks on the valleys and ravines as due to fractures and subsidences or upheavals of the earth's crust; the other, while far from ignoring the influence of subterranean movements, holds that these have not been the chief cause in determining the present form of the ground, but that the valleys are due in the main to denudation, or the erosive action of rains, streams, ice, and other sub-aërial forces. Of these two opinions the latter alone appears to me tenable with regard to the hills and valleys of Scotland; and I would here state in a few words the grounds for the belief.
It should be borne in mind, that, in dealing with the past history of our planet, the element of time ought never to be lost sight of. To turn away from the known and visible causes of change, and to imagine the former presence of others far more stupendous, because the results achieved seem otherwise inexplicable, is to substitute mere speculation for inductive reasoning. In all such attempts we make the fatal error of forgetting that, in the geological history of our globe, time is power. It may not be easy to get thoroughly rid of the natural tendency to associate great effects with great causes; but if one can free himself from this prejudice, he will probably be led, in the spirit of Hutton, to perceive that there appears to be no great change in the configuration of the