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I left, to see the now broken granite rocks, under whose shelter Pococke and Windham, the first English adventurers into this valley in 1741, slept; and which has since then been moving down the ravine, "sloping amain," at the rate of one foot per day, sweeping an immense moraine of granite and earth along.
There is so much of the terrific and the peculiar connected with this Alpine phenomenon, that much scientific observation has been given to it. The deductions of scientific men are as remarkable as they are interesting, in relation to the origin, movement, former existence and effect of glaciers. The best information I can obtain is the following. It contains the eclecticism of the subject:
The summit of Mont Blanc, when its fused granitic mass rose up from the bowels of the earth, was for some time as bare as are the wasted peaks of the Aiguilles which surround it. The heat gradually subsided, an immense quantity of snow began to fall, as it now does, on the elevated rocks and valleys. In the highest regions, where rain is unknown, evaporation, proceeding from the extreme dryness of the atmosphere, causes these flakes to descend in particles somewhat resembling hail, whose loose dry grains, heaped on each other, are incoherent and form what is termed the neve. A great part of this is swept down on the lower stages of the mountain by those impetuous currents of air which almost constantly reign at great heights, at other times snow containing some portion of moisture is whirled up across the summit from the lower and warmer regions; during summer the solar rays, not having yet lost their calorific intensity by descent through the atmosphere, act with extraordinary force, avalanches are detached, and the moisture caused by the direct action of the heat on the exterior, as well as that arising from clouds which at times envelope the summit, is speedily absorbed by the remainder of the porous mass. To this succeeds nightly congelation and expansion, so that the neve descending gradually from this, combined with other causes, in the same manner as the low glacier, forms the reservoir of those vast ice
streams which glide into the upper valleys of the Alps. Successive falls of snow, their thaws and congelations, are therefore the undoubted origin of the first glaciers.
Their movement is very differently explained. De Saussure attributes it to gravitation, which is improbable, because, if pressure at ergo were the sole cause, the entire body would slide down into the plains with gradually accelerated velocity. De Charpentier and Agassiz are partisans of the dilatation theory, supposing that daily thaw, constantly succeeded in the whole body by night frosts and expansion, causes the forward motion. This is refuted by the ascertained fact that congelation does not every where and always take place throughout the glacier, for the cold, except at its edges and thinner parts, penetrates no farther than into the earth when covered by a mantle of snow. Nocturnal cold merely suffices to dry up the streamlets at the exterior during summer, and the constant wasting of the glacier during that season proves that frost does not then exercise a dilating effect. While the prolonged winter season continues, it of course reaches a greater depth, but if entirely dependent on alternate thaw and frost the whole body would then freeze hard and not move at all.
Whoever examines the composition of the glacier will readily perceive it to be an eminently fragile body composed of a porous and plastic ice, different from that which forms on the surface of lakes and rivers. The manner in which it moulds and adapts itself to every bend and corner of a rocky valley proves i sits ductility. It is in short a semi-solid or viscous composition, urged downwards by its own weight and a mutual pressure of its coherent parts. The mass is detached from its bed of rock by the subterranean heat of the globe, the infiltration of rain-water, and of the moisture produced by exterior thaw. Being the outlet of the winter world it is fed in the upper regions by dilatation of the neve, the descent of avalanches, and by snow swept down on it from the summits.
Thus urged onwards, the daily waste below is replaced by
daily descent from above. Crevasses proceed from forcible separations caused by inequalities of the rock, its occasional swells, or abrupt descents, over which the viscous or half rigid mass strains forward. When an obstacle occurs, the glacier becomes transversely rent, its lower portion is separated, and proceeds, the fissure gradually enlarging, until closed up by pressure behind or accumulation of ice debris, to form afresh if the cause is renewed. Though the identical ice of which they, or the deep gully holes often seen on the glacier are composed, may, after a lapse of time, have advanced some hundred feet, the rents and fissures will always be found at the same spot like the eddies and deep pools in particular parts of a stream. Local conformations mould the ice; its centre advances more rapidly than the sides which it drags along; its upper surface more than the under one; the lower end more than the source or reservoir. The velocity is checked by cold but augmented by sunshine, thaw, or rain. The forward movement, through perpetual night and day, is irregular, and much greater in spring than summer, in summer than in autumn and winter. During the hot season the glacier wastes away in all its parts; during winter it is expanded upwards by frost and agglomeration to its former level, and, the progress being retarded, all its parts crowd together.
The abrasion of the diamond and the force of the lever give to the glacier an immense power. Hence the stupendous rocks found in places where no other agency could have borne them. Evidences are numerous in the vale of Chamouni, of this very glacier having torn away great portions of the mountain, and filled the vale to the height of five hundred feet or more. Indeed, when we consider the effect of this silent, slow, but resistless messenger from above, the fact that it overthrows or surmounts almost every opposition, and that a very slight depression of the present temperature of the earth would cause its increase ad infinitum, we must admit that such a mighty instrument may prove, in the hands of Providence, an agent more destructive of our globe than fire or water, since no effort can arrest, no obstacle prevent or divert its awful progress.
Ascending the Pavilion, we may discuss over a little Alp of strawberries, blanched with sugar, which quickly disappears under the keenness of the appetite-the science of this immense sea, more at leisure. While eating, however, I opened the register, and found that Montanvert had proved a Parnassus to some genius incognitus, who poured forth his sentiment right happily in the following
SONG OF THE MER DE GLACE.
"There ne'er was seen, on earth I ween,
On our Alpine pass of the Mer de Glace
"Our feet have pressed the snowy crest
Of these wild waves deep and strange,
On whose strength of rock, writes the whirlwind's shock
"And the mountains to-day, as they have alway
Since time began to be,
With reverend head guard the royal bed
Of that sleeping silver sea.
"And while ages fail, they'll tell the tale
"Truly," says an annotation, "we forgot it was July
'Which, remembered in time,
Would have spoiled the rhyme.""
Other bards celebrate their drizzling days in Jeremiads and dripping lines, but there was no piece which struck me as worthy of a transcript, except the above.
We descended rapidly the great highway-my mule, like a gallant soldier, ever preferring the post of danger, and always provokingly hanging his ears over the most awful chasms, and
eating grass just where one feared to be toppled headlong into the awful gorges. But it is great, to be high and aloof from the world and its vexations. For a lawyer to be 7,000 feet high, it is almost Paradise. No judge, jury or sheriff; no special pleading or demurring (save that of the mule) away up here. Chitty has no Precedent for the Dru; and Tidd, in all his "Practice," never drew so complex, yet so simple, a declaration as Mont Blanc draws against the serene azure. Never was I so near the great high Chancery, where all things are tested by the conscience, and not by the letter merely.
We bade adieu to Mont Blanc on Tuesday, to see his radiant face again from St. Martin's bridge, upon the road to Geneva, where it was said that one of the finest views could be had of him and his chain. St. Martin's is twelve miles from Mont Blanc. As you look up the valley of the furious Arve, there arises the Mount Foreclaze, covered with pines and pasturage; over these, the needles point around the Mer de Glace, and mingling with them, are the snow tops, consisting of great fields, which centuries have been piling, and which branch down the ravines in moving glaciers. The black pines gloom along the twelve mile perspective. It has been raining; the clouds are heavy, and hang around the mounts in variegated and wild gloominess. A great terraced point, swelling upward in cultivation, is upon our right, across the vale, while a stupendous castellated temple is upon our left. The birds sing, and the Arve roars. The mighty spirit of the spectacle glides along the walled ridges, and enters the soul, bedewing it with 'thanks and mute ecstasy.' Nature has many thoughts encased within, and flowing from, these rocky mounts, to be pondered with profit and delight. The reader who has not had the advantage of realizing the beauty and immensity of an Alpine scene, should at least turn back to our frontispiece, in which the talented artist, Hinshelwood, of New-York, has re-pictured to our memory the sublime view of Mont Blanc from St. Martin's bridge. The engraving is from a drawing upon the spot, and faithfully fol