The second great use of mountains is to maintain a constant change in the currents and nature of the air. Such change would, of course, have been partly caused by differences in soils and vegetation, even if the earth had been level; but to a far less extent than it is now by the chains of hills. Exposing on one side their masses of rock to the full heat of the sun-increased by the angle at which the rays strike on the slope-and on the other casting a soft shadow for leagues over the plains at their feet, hills divide the earth not only into districts but into climates, and cause perpetual currents of air to traverse their passes, and ascend or descend their ravines, altering both the temperature and nature of the air as it passes in a thousand1Subterranean: underground.
2Perennial: never failing; unceasing.
different ways. They moisten the air with the spray of their waterfalls; suck it down and beat it hither and thither in the pools of their torrents; close it within clefts and caves, where the sunbeams never reach till it is as cold as November mists; then send it forth again to breathe softly across the slopes of velvet fields, or be scorched among sunburnt shales1 and grassless crags. Then they draw it back in moaning swirls through clefts of ice, and up into dewy wreaths above the snowfields; piercing it with strange electric darts and flashes of mountain fire; and tossing it high in fantastic storm-cloud, as the dried grass is tossed by the mower, only suffering it to depart at last when chastened and pure, to refresh the faded air of the far-off plains.
The third great use of mountains is to cause perpetual change in the soils of the earth. Without such provisions the ground under cultivation would in a series of years become exhausted and require to be upturned laboriously by the hand of man. But the elevations of the earth"s surface provide for it a perpetual renovation.
The higher mountains suffer their summits to be broken into fragments and to be cast down in sheets of massy rock, full of every substance necessary for the nourishment of plants; these fallen fragments are again broken by frost and ground by torrents into various conditions of sand and clay - materials which are distributed perpetually by the streams farther and farther from the mountain"s base.
1 Shales: kind of rock.
Every shower which swells the rivulets enables their waters to carry certain portions of earth into new positions, and exposes new banks of ground to be mined in their turn. That turbid foaming of the angry water, that tearing down of bank and rock along the flanks of its fury, are no disturbances of the kind course of nature; they are beneficent operations of laws necessary to the existence of man and to the beauty of the earth.
The process is continued more gently, but not less effectively, over all the surface of the lower undulating1 country; and each filtering thread of summer rain which trickles through the short turf of the uplands, is bearing its own appointed burden of earth to be thrown down on some new natural garden in the dingles2 below.
It is not, in reality, a degrading, but a true, large, and ennobling view of the mountain ranges of the world, to compare them to heaps of fertile and fresh earth, laid up by a prudent gardener beside his garden-beds, whence, at intervals, he casts on them some scattering of new and virgin ground. That which we so often lament as convulsion or destruction, is nothing else than the momentary shaking of the dust from the spade.
The winter floods, which inflict a temporary devastation3,bear with them the elements of succeeding fertility; the1 Undulating: rolling; rising and falling in wavelike forms. 2 Dingles: narrow dales; small valleys.
3 Devastation: ruin; destruction.
fruitful field is covered with sand and shingle1 in momentary judgment, but in enduring mercy; and the great river, which chokes its mouth with marsh and tosses terror along its shore, is but scattering the seeds of the harvest of futurity and preparing the seats of unborn generations.
The three great functions which I have just described, - those of giving motion and change to water, air, and earth,- are indispensable to human existence; they are operations to be regarded with as full a depth of gratitude as the laws which bid the tree bear fruit or the seed multiply itself in the earth.
And thus those desolate and threatening ranges of dark mountain, which, in nearly all ages of the world, men have looked upon with aversion or with terror, and shrunk back from as if they were haunted by perpetual images of death, are, in reality, sources of life and happiness far fuller and more beneficent than all the bright fruitfulness of the plain. The valleys only feed; the mountains feed and guard and strengthen us.
We take our idea of fearfulness and sublimity alternately from the mountains and the sea; but we associate them unjustly. The sea, with all its beneficence, is yet devouring and terrible; but the silent wave of the blue mountain is lifted toward heaven in a stillness of perpetual mercy. And the one surge, unfathomable in its darkness, the other, unshaken in its faithfulness, forever bear the seal of their appointed symbol:-"Thy righteousness is like the great mountains: Thy judgments are a great deep."1 Shingle: coarse gravel.
