of soil at its junction with the Mediterranean, has encroached upon the sea, only to the extent of half a mile, since the time of Herodotus.

The ocean is known, from its effects upon our coasts, to be gradually enlarging its dominion in some places and retreating from the land in others, demolishing on one side the rocky bulwarks of our island, on the other, raising sandy ramparts on which to break its billows and shelter the land from its fury. In fact, a principle of compensation seems everywhere to regulate the movements of this mighty element, and there appear to be no indications of that march of Neptune to universal empire which Mr. Lyell seems to apprehend. *

In Alpine countries, where the torrents, "nature's saws," as Playfair says, "are continually at work in cutting down the mountains," geological changes on a scale of greater magnitude are constantly going on. Thus in Switzerland, the fall of an enormous mountainmass, undermined by the action of the elements, is not an uncommon occurrence. The fall of the Rossberg in 1806, covered one of the beautiful valleys of that country with desolation, and buried many villages with their inhabitants beneath its ruins. In Savoy, near Servoz, there are the remains of a similar catastrophe, which took place in 1749; and a neighbouring mountain,

* "The changes of territory" says Mr. Lyell "within the general line of coast are all of a subordinate nature, in no way tending to arrest the march of the great ocean, nor to avert the destiny eventually awaiting the whole region: they are like the petty wars and conquests of the independent states and republics of Greece, while the power of Macedon was steadily passing on and preparing to swallow up the whole."

which "hangs in doubtful ruin o'er its base," threatens to renew the scene of devastation at no distant period. All mountainous countries present us with phenomena of the same description: mountain masses, like other parts of the earth's surface, being composed of strata of different density and degrees of hardness, where the base happens to consist of a soft material and to be exposed to the atmosphere, it undergoes disintegration, and the superincumbent mass is precipitated into the valley below.

Then, there are the Glaciers, serving as the vehicle of transport to enormous masses of rock. They who have not seen these phenomena, can form no idea of their magnificence. They consist of enormous masses, or rivers, or as the most considerable of them are termed, in the inflated language of France, Seas of ice, Mers de Glace, formed in the valleys of the higher regions of the Alps, from the subsidence and partial dissolution of the mass of snow, which, as is well known, at a certain height varying with the latitude of the place, perpetually covers the sides and summits of lofty mountains. These have accumulated to a vast extent, and have gradually advanced into the lower valleys-into the region of cultivation, where they have become permanently located in the midst of corn-fields and orchards; and there, with chilly aspect, defy the rays of a southern sun. In the Alps alone, there are one hundred and thirty square leagues of this icy territory, and all other great mountain-chains present the same phenomena. The Mer de Glace of Mont Blanc, the most remarkable glacier of the Alps, is twelve or fourteen miles in length, with an average width of about a mile, and

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

D

* Berg is the German word for mountain.

isles;

We

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. 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 Etna, 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.