Imágenes de páginas
[ocr errors]


the water opened a passage for itself was continually growing weaker, found by breaking the glacier, its level had itself at last sufficiently strong to sunk forty-five feet below the greatest push forward this soft soil from the height which it had ever reached. foot of Mount Mauvoisin, and to

This diminution of the lake having wear itself a passage between the glataken place at the top, that is, at the cier and the layers of the rocks which point where it had the greatest breadth, composed the mountain. Immediateit follows, estimating the breadth at ly the lake rushed out all at once ; only six hundred feet, that the gallery the ice, which still remained between had effected a diminution of the water the gallery and Mount Mauvoisin, of the lake of two hundred and seventy gave way with a horrible crash; and millions of cubic feet at least : so the body of the water forced its way out that, at the moment of the breaking with such impetuosity, by the great up, it did not contain more than five opening which it had thus forced behundred and thirty millions of cubic tween the glacier and Mount Mauvoifeet of water, in place of the eight sin, that in half an hour the lake was hundred millions which it contained completely emptied, and the five hunthree days before.

dred and thirty millions of cubic feet of At the moment when the gallery water which it contained, thundering began to produce the desired effect, down into the valley with a rapidity the water which ran through it, rush- and violence of which no idea can be od out of the outlet

in a cascade, into formed, destroyed every thing in their the old bed of the Dranse, below the

It is probable, that the rushglacier, quickly melted the ice, and ing out of the lake would have been eat away the floor of the gallery at its still more rapid, had it not been for inouth. The water which had insinuated the existence of a narrow gorge immeitself into the rents and crevices, which diately below the glacier, between penetrated the glacier in some places, Mount Pleuseur and an advanced point especially at the edges, caused enor- of Mount Mauvoisin. The water rushmous masses of ice to fall with a crashed into this gorge with such force, from the lower sides of it. By these that it swept away the bridge of Mauvarious united causes the gallery lost voisin, situated 90 feet above the level considerably in length ; and the case of the Dranse, and rose many toises cade hollowing out a very deep fur- above the projecting mass of Mount row, the mass of the glacier, which at Mauvoisin. After leaving this narrow this point formed the retaining wall of channel, the enormous mass of water the lake, diminished so much in thick- spread itself over a broader part of the ness, that the floor of the gallery, Val de Bagne, which forms a pretty which at the outset was six hundred large bason, contracted at the botfeet in length, was reduced to eight tom by another gorge of the valley, feet at the moment the whole lake through which it again escaped with forced the passage.

such violence, that it carried off every It was not, however, the giving way thing which covered the rocks, even of this wall of ice, now become so detached some of these, and hurled slight, which was the immediate cause them into the abyss. A new bason in of the frightful deluge--that was the valley then received this tremend caused by another accident. After ous liquid mass, which swept on every the cascade had formed a channel side the foot of the mountains, carrysome hundred feet deep, in the lower ing thence forests, detached rocks, mass of the glacier, and, after pene- houses, barns, cultivated land, and laytrating more and more, had at lasting waste even the base of those steep, fallen upon the base of Mount Mau- but more or less cultivated, sides of the voisin, which passed under the gla- two chains of mountains bounding this cier, and against which the latter unfortunate valley. Many contractions, rested—the base of the mountain not farther down the valley, raised the wabeing at that point composed of ter to a considerable height, and inrocks, but of a thick mass of debris creased the fury with which it inuncovered with vegetable mould; the dated the lower plains, where every cascade, I say, attacked this loose obstacle was overthrown and swept amass and carried it off by degrees; way. Enormous heaps of pebbles and and thus the water filtering into the rocks, which the floods had carried off* earth, which it liquified, and which higher up, were deposited in the plains,

which, but a moment before so beau- of the water of the lake, drawing with tiful and so populous, were now con it all the debris, and forming a column verted in a moment into a dreary de- of more than 530 millions of cubic feet, sert. On reaching Chable, one of the passed every part of the valley. The principal villages of the valley, the food then furnished in every second water was confined between the piers 300,000 cubic feet of water. The of a strong bridge ; the body of Rhine, below Basle, where all its wathe flood, which appeared to contain ters, from the Tyrol to the Jura, are even more debris than water, rose united, gives, during the season when more than fifty feet above the ordi- its waters are highest, about 60,000 nary level of the Dranse, and be cubic feet of water per second. The gan to encroach on the inclined flood of the unfortunate valley of plain, upon which the church and Bagne, then, must have contained five the greater part of the village are times more water than the Rhine bears built. A few feet more, and the when at its height. This comparison water would have reached the village may aid us to form some idea of the and destroyed it. At that important prodigious mass of water which promoment the bridge gave way, the duced such dreadful effects. houses at its two extremities were Agreeably to the information I colswept away; and the passage being lected, the flood took up thiry-five now clear, the frightful mass of water minutes in coming from the glacier to and rubbish spread itself over the wide Chable. The distance between these part of the valley, as far as St Bran- two points, following the bed of the chier ; every thing in its course was Dranse, is about 10,000 feet. The undermined, destroyed, and carried off. water, then encumbered with all the Houses, highways, fields covered with rubbish, moved with the velocity of the finest crops, noble trees loaded thirty-three feet in a second. The with fruit, every thing was swallowed velocity of the most rapid rivers is from up and devoured. The moving chaos, six to ten feet per second ; very few charged with all thesespoils, now throws attain to the velocity of thirteen; itself into the narrow valley of St Bran- thus, in the rectilineal and perfectly chier à Martigny, through which lies regular canal of Mollis, the Linth, afthe road of St Bernard ; as yet nothing ter this canal is full, flows with a veresists the merciless torrent; all the locity of twelve feet per second. That parapets built along the edge of the of the torrent of the Val de Bagne, Dranse are precipitated into the flood, multiplied by the half solid mass which which, reaching Martigny, and es was in motion, explains extremely caping from the narrow valley, dif- well the force with which forests, fuses itself over the plain, forming the houses, and rocks, have been swept off great valley of the Rhone; covers the and carried to a distance, fields and orchards; runs through the In passing from Chable to Martigtown of Martigny; carries off from ny, the flood must have occupied about thence houses and barns; covers the fifty-five minutes. The distance bewhole plain with thick mud; thou- tween those two places, following the sands of trees torn up by the roots; windings of the valley, may be about wrecks of houses and furniture ; dead 60,000 feet; the medium velocity of bodies of men and animals; and, branch- the current then, in this extent, was ing out, at last it precipitates itself in- about eighteen feet per second. The to the bed of the Rhone. That river inclination of that part of the valley being at the time little affected by the being less than the upper portion of water of the mountain snow, which it, and the water having lost a part had not yet begun to melt, received, of the impulse resulting from its fall without farther injury, all that remain- by the open gorge in the glacier, we ed moveable of that terrible flood, may suppose that the velocity of the which had just laid waste one of the current was considerably diminished finest vallies of the Alps, to the extent in this valley, which was lower and of of ten leagues in length.

a more uniform breadth; the time According to the unanimous testi- which the flood took up in passing mony of the inhabitants, the flood took through it, therefore, was in all proup half an hour in passing every point bability longer than that occupied in which it reached ; thus, in the short traversing the upper valley. space of thirty minutes, the whole mass From Martigny to St Maurice, the

water of the flood, now contained in Mauvoisin, the cascade which would the bed of the Rhone, arrived in seven- have been thus formed, and which would ty minutes, the distance being about have tumbled at once upon the loose 50,000 feet; thus, the velocity of the earth which covered the rocky strata river was necessarily from eleven to of Mount Mauvoisin, would have imtwelve feet per second. The flood be- mediately decomposed and carried off ing much diffused and divided in the this loose mass of rubbish and vegetaplain of Martigny, the time occupied ble mould, and the lake would thus in crossing that district was of course have forced a passage equally abrupt longer than that occupied in its pas- with that which took place. But a sage through the higher vallies. threefold mass of water suddenly es

Finally, from St Maurice to the caping from this great reservoir, would Lake of Geneva, a distance approach- certainly not have left the vestige of a ing to 80,000 feet, the water and the habitation either in the valley of rubbish took up about 230 minutes, Bagne or St Branchier, and most prowhich gives a velocity of about six bably all Martigny would have been feet per second. This velocity was, utterly destroyed. There is still anno doubt, much greater immediately other circumstance to be considered, below St Maurice, and much less near in order completely to appreciate the the Lake of Geneva; but the velocity extent of the advantage which resultof six feet per second expresses the ed from that gallery which was so medium velocity of the whole of this cleverly executed. We have seen that passage.

the lake rose daily, during its execuWe should deceive ourselves, were tion, nearly two feet. After arriving we only to estimate the advantage at a height where its surface would which resulted from the formation have been increased in a greater proof the gallery through the new gla- portion, this rising would no doubt cier, by the mass which passed have diminished in spite of the exthrough it in the course of three traordinary melting of the snow and days; for not only did it draw off the ice, occasioned by the greatest from the lake the 370 millions of heat. But, granting that the lake cubic feet which issued by it, but it would have continued to rise at the prevented the elevation of the level of same rate, the moment of the breakthe water to the height of the point of ing up would have been delayed at contact of the glacier with Mount least a month, and would thus have Mauvoisin, a limit which, as we have happened at the time the waters of seen, was sixty feet higher than the the Rhone are highest. The 530 gallery ; the lake would therefore millions of cubic feet of water which have increased 15,000 feet in length, it furnished to the river, were run off and its breadth would have exceeded without causing damage on the 16th 1000 feet. Again, sixty feet of ad- June, a period when the water of the ditional surface height would have river was still pretty low. But if furnished a body of 900 millions of these 1730 millions of cubic feet had cubic feet of water ; which, added to been thrown into the bed of the Rhone the 800 millions in the lake before the when full, assuredly the whole of the opening of thegallery, would have raised bottom of the broad valley of the the entire volume of water in the lake Rhone, from Martigny to the Lake to 1700 millions of cubic feet. Now, of Geneva, would have shared, more as the breaking up of the glacier only or less, the disastrous fate of the valgave 530 millions of cubic feet of ley of Bagne. water, its mass was reduced to less The new glacier of Mauvoisin, howthan a third of the water which ever, still exists in the channel of the would have been accumulated in the Dranse. The mass which has been carlake, but for the judicious steps tak- ried off by the effect of the gallery, and en by the government of the Valais, the bursting of the ice, forms but a by the advice and assistance of Mr very small portion of it; the channel Venetz.

by which the lake escaped is even shut There can be no doubt, that if these up by the blocks of ice which have 1700 millions of cubic feet of water fallen from the upper glacier, and by had accumulated in the lake, and had masses which are occasionally detachthe latter begun to exceed the limit of ed from the edges of the new one. contact between the glacier and Mount This accumulation of ice-blocks in the


mouth of the lake is even already so glacier, or, rolling perhaps down its compact, that the Dranse can hardly side to its base, they would only serve work its way below the glacier ; and a to increase its circumference; and one new lake, which, on the 24th of July, avalanche would increase, and probably was a full quarter of a league in length, double the mass which had been rethough as yet not very deep, announ- moved with so much expense and dances, that the causes of a new flood still

ger. exist in this unfortunate district of the There is only one means by which valley. If the internal heat of the this valley may be for ever put beyond earth succeed in melting the principal the reach of milar, or even those supports upon which rests the enor still greater disasters which threaten mous cone of ice which has shut up the valley of the Rhone, as far as the valley, it will sink a little, and will the lake of Geneva. This consists in one day or other close up the nar- opening gallery in the calcareous row outlet which the river still finds strata of the foot of Mount Mauvoisin, beneath it. The heat of the atmos or Pierre à Vire, which is immediately phere has even little influence on the opposite to the fatal glacier. This surface of the glacier ; threads of wa subterraneous gallery ought to be ter, hardly visible, trickle down its made so long, that its entrance and sides; and, at four o'clock in the outlet should be removed from the afternoon, the greatest part of the base of the glacier to such a distance glacier is already in shadow under as to prevent all risk of either the the high and precipitous side of the one or the other opening being chokPierre à Vire, a peak which overtops ed up, and thus rendered useless. It Mauvoisin. The nights are grow, would be necessary to make the galing longer; one month more, and lery of a size sufficient to allow the the new snow will cover the glacier ; whole of the Dranse to pass even at every return of a fine day will melt the period of the highest floods. For the snow on the sides of the neigh this, it appears a gallery, ten feet high bouring mountains, or produce ava- by eight feet broad, would be suffilanches which will augment the gla cient; for if the water run through cier, rendered more homogeneous by it with a velocity of eight feet per sethe cold water which filters through it cond, as will be the case by giving the and freezes. The winter, and even gallery the greatest possible inclinathe approach of the spring, will mul tion, a mass of water of 640 cubic feet tiply the causes of the increase of the may pass through in a second, which glacier, which bars the valley, and gives fifty-five millions of cubic feet which threatens, in the most alarming in a day, and this volume exceeds the manner, the repetition in the course of estimate which has been made from next year of that scene of horror of observations, of the quantity of water which we have now been reading the which the bottom of the valley could details. The contents of the enor- furnish even during the greatest meltmous mass of ice which forms the ing of the snow. By means of such a barrier has been calculated; it would gallery, the length of which might be appear to consist of more than fifty 2000 feet, we should for ever give the millions of cubic feet. We may con Dranse a free issue by the bottom of the trast with it the powers of all the a- valley; and this outlet would be then gents which physics and chemistry altogether independent of the state of furnish to man, and which he so often the glacier. We could even easily abuses for the destruction of his species; prolong this subterraneous outlet, in but all these are as nothing against the improbable case of the increase of this gigantic mass, the approach even the glacier rendering it necessary to to which is dangerous, on account of change the entrance or the outlet of the detached pieces of ice and rock the gallery. which are continually falling from the Ail Switzerland is hastening to alupper glacier. If the most extensive leviate, by fraternal aid, the misformines were driven into it, the force of tunes of the inhabitants of the valley the powder would either be lost in the of the Dranse; a great number of focrevices which traverse the glacier, or reigners, among whom the English cause new ones; or if, in more favour are distinguished, having contributed able circumstances, large blocks were to the same end. But what avails it blown up, they would fall upon the to rebuild houses in ruins, if the same

catastrophe is impending over them? If the Dranse be permitted to folWhile, if the greater part of the money low the disorderly course which it has contributed by benevolence were em- received from the flood, it will underployed on the execution of this gal- mine more and more the sides of the lery, the whole valley would be for mountains of the valley of Bagne ; its ever safe ; an advantage, without water, increased by the melting of which every other will remain preca- the snows next spring, will unite with rious.

that which has insinuated itself into the There is still, in the present state of numerous crevices, and produce more the valley of Bagne, a very disagree- extensive destruction; the Dranse will able circumstance, which cannot be be filled with these, and its course amended but by the united labours will thereby be rendered more irreguof the inhabitants, or by the inter- lar and destructive even to the Rbone, vention of government. The enor the bed of which is at present rising in mous heaps of rocks and pebbles which a very sensible degree, and threatens the food has formed in the valley, injury to the lower parts of the valobstruct almost every where the course ley. If every proprietor in the valley of the Dranse, and throw it upon the of Bagne is allowed to erect his dykes steep declivities which bound it. Here, at pleasure on the bank, the evil will as in every spot where a vigorous ve only be so much the greater, for these getation, either natural or the effect partial operations will unite with the irof agriculture, is produced on the regularities of the natural course of the slope of the mountains, these declivi- river to render it still more destructive. ties are composed of debris from the If it is meant to protect the interests of upper rocks, which cover the base, ori- the valley, and to turn to the best ginally naked and uncultivated: this account the small means left to the again is covered with a layer of vege- unfortunate inhabitants, they must not table mould, generally pretty thin, be permitted to waste their resources which renders it fertile. But already on partial operations on the torrent. the base of these slopes, more or less Let as regular a course as possible be productive, and covered with forests, marked out for it in the middle of the has been attacked in many quarters, valley; the perfect safety of all the poand undermined at the base by the pulation will then be insured, with the destructive effect of the flood; and least possible expense ; the torrent will thus the upper parts of these steep de- be removed from the foot of the mounclivities are without support, and be- tain sides, by giving it the straightest gin to slide into the bottom of the possible direction; the largest of the valley. Broad and deep crevices, great rocks and pebbles, which cover which are sometimes a thousand feet the extensive plains, will be accumuin length from the bottom of the val- lated as much as possible at the foot ley upwards, indicate this sliding down, of the slopes already attacked; and whose consequences are so much to while dangerous and sudden overflowbe deprecated. The melting of the ing will be prevented, the bottom of the snows next spring will fill these rifted valley will be cleared of the greatest obslopes with a great quantity of water, stacles to its renewed cultivation. The which will soften, and cause them to union of all human energy, wisely dishrink and tumble down, as gen- rected, is required to diminish the evils erally happens in those which so which extraordinary accidents very ofoften lay waste the different vallies ten occasion in the Alps. Individual.exof the Alps. The evil is not limited ertion can do little against such misforto the destruction of the vegetation of tunes, and partial charity but too often these declivities, but the torrent of diverts the unfortunate object of it from the valley is filled with an enormous the means which would effectually aquantity of pebbles, which it rolls meliorate his condition. The populaalong as long as its slope gives it tion of a whole district is very often impulse : it is in the plains or con- insufficient to repair the ravages of the siderable vallies that these rolled elements in our Alps. A greater union pebbles are deposited, elevating the of strength and means is required to rebed of the torrent, causing the banks medy great misfortunes, and to guard to give way, and producing these in- against their return. A whole valley, undations which so often desolate our nay, a whole canton, ought sometimes low vallies.

to unite to obtain this end. But after

« AnteriorContinuar »