fills, to the depth of several hundred feet, a deep gorge or depression in the side of the mountain.— Viewed from above,* it can be compared only to a turbulent river of dazzling brightness, whose waves are tossed about in the wildest confusion-nothing but motion being wanting to complete the illusion. If any one who has seen the ocean in a storm, can picture in his imagination the effect of a sudden consolidation of the raging mass of waters when heaving in all its fury, he will have a faint conception of this singular scene. On a closer inspection, it is found to consist of deep ravines, and irregular ridges and masses of ice of adamantine hardness, bearing enormous fragments of rock on its surface, and traversed in every direction with fissures or chasms of awful depth-the chilly grave of many an adventurous traveller. Some lines of a modern poet well describe a glacier.

"Wave upon wave! as if a foaming ocean,

By boisterous winds to fierce rebellion driven,
Heard-in its wildest moments of commotion,

And stood congeal'd at the command of Heaven.
Its frantic billows chained at their explosion

And fixed in sculpture! here to caverns riven,
There petrified to crystal-at his nod,

Who raised the Alps an altar to their God."

As a geological agent its effects are considerable.

*The point of view from which the glacier is generally observed, is Montanvert, about eight thousand feet above the level of the sea, where a temple as it is called, dedicated "to Nature," has been raised for the accommodation of her devotees, who come from all parts of the world to worship at this frigid shrine.

The vertical masses of granite and schistose (slaty) rocks, which undergo disintegration from the action of the elements, fall in large masses upon the surface of the glacier, and are carried along with it by the slow and imperceptible, but irresistible motion, (varying with the inclination of its rocky base,) which it has been proved to have. In this manner, huge fragments of inaccessible rocks from the very summits of the mountains, are conveyed many miles to the verge of the glacier, whence they are precipitated with vast masses of congealed snow into the valley beneath, occasioning in their fall the phenomena of avalanches, those "thunderbolts of snow" whose reverberations make the mountains tremble: here they meet with the torrent by which, lashed, broken, and comminuted, they are transported to a great distance: for out of the dark icy caverns of the glacier rush with full-grown vigour, some of the mighty rivers of Europethe Rhine, the Rhone, the Po, and the Arve.

In the northern regions of the world, this agent is infinitely more active, and we there find it engaged in carrying out to great distances at sea, enormous rocks and earthy masses. Thus on the frigid coast of Greenland, the glaciers, which in the Alps descend into the elevated valleys, come down in the same manner to the level of the ocean, into which they are precipitated by accidental circumstances, and from their less specific gravity, float off and sail with their heavy cargo whereever winds and tides impel them. The northern seas are full of these ice-bergs as they are termed, and they have been known to stray as far south as the Madeira

* Berg is the German word for mountain.

D

isles;

and Captain Scoresby states, that he has seen masses of rock borne on these icy islets which would weigh from fifty to one hundred thousand tons. We shall hereafter have occasion to call in the aid of this powerful agent to account for phenomena where it has long since ceased to operate, but where it is inconceivable, that any other cause with which we are acquainted, could produce the effects.

But of all the agents now in operation to modify the exterior surface of the globe, the volcano, and its attendant the earthquake, from which this portion of the world is happily exempt, are the most awful in their phenomena, and the most extensive in their effects. Volcanos, in the strict sense of the term, are merely those conical chimneys or vents, by which vapours, or solid matter in a state of fusion or vitrification, are ejected by the expansive force of heat, from the internal fires, by some unknown cause excited, deep below the surface of the earth. Upwards of two hundred of these, in various parts of the world, are known to be in a state of permanent ignition, constantly giving out fire, smoke, or vapour, and occasionally like mighty cauldrons, boiling over streams of red-hot melted matter, or with an explosive force, violent beyond conception, shooting forth cinders, ashes, and vitrified matter. Volcanos generally are lofty mountains such as Ætna, with

"Entrails fraught with fire

That now cast out dark fumes and pitchy clouds,

* From the south pole they have also travelled northward as

far as the Cape of Good Hope.

Vast showers of ashes, hov'ring in the smoke,
And now belch molten stones, and ruddy flames
Incensed, or tear up mountains by the roots,
Or fling a broken rock aloft in air.”*

But vents or orifices in the level surface of the country, sometimes give relief to the explosive forces, as the Geysers in Iceland, where steam is evolved with amazing force, and water thrown up as in artificial fountains, to a great height. In the case of elevated volcanos, the mass is most frequently formed by the gradual accumulation of ejected matter.

Violent eruptions are generally attended by earthquakes, and the vast extent of the effect of these, proves that the exciting cause is very deeply seated in the interior of the earth. Thus the shock of the terrible earthquake which destroyed the City of Lisbon, in 1775, was felt throughout the whole of Europe, from Norway to the coast of Africa, in the Madeira isles, and the West Indies; and at the destruction of Lima, in Peru, in 1746, not only was the whole continent of America convulsed, but the shock was propagated across the Atlantic and sensibly perceived on the shores of Europe.

Strabo, an ancient Greek geographer, first suggested that volcanos were "safety-valves" to regulate and restrain the action of the explosive forces in the earth's interior; and some geologists have asserted, that it is owing to the protection which these afford, that the earth is not now convulsed as it appears to have been in former periods; while astronomers reconcile us to the horrors and inconveniences of volcanic eruptions, by

* Virgil, Æneid, lib. iii.

assuring us, that without these "safety-valves," we should in all probability be blown into space, with the shattered fragments of the globe in which the explosive materials are generated: which when recovered from the shock might move in convoy, each in its own course, round the sun, like the little planets Ceres, Pallas, and Juno, whose origin they attribute to a similar catastrophe. It is certain, that where these safety-valves are absent, the surface of the earth has undergone the most considerable derangement; the accumulation of matter ound the crater of a volcano, the result of repeated eruptions, is inconsiderable, compared with the mighty upheavings of continents and islands, which our own. times and historical records, as well as geological evidence attest. In her efforts to be free, Nature has struggled with the greatest violence. Thus the bed of the ocean has been raised and rent, and islands thrown up high above its level in our own times. The latest instance on record is that of 1831, in the Mediterranean, between Pantellaria and the coast of Sicily, the progress of which was watched by scientific observers. In 1811, in the Azores, a similar creation, effected in the course of a few days-the formation of an island in the Atlantic a mile in circumference, and three hundred feet high-was witnessed from the shores of Saint Michael's. Numbers of such instances are on record in the Azores, the Grecian Archipelago, and the Ionian isles, in contemporary times, and Pliny enumerates several islands, which in his time were known to have arisen from the depths of the Mediterranean, at the birth of which Vulcan and Pluto had the credit of presiding, for in all cases their first appearance was attended by volcanic phenomena.