Often, if a bit of overhanging snow falls on the upper part of the hill-side, or if an animal disturbs the newly fallen mass, or perhaps if a gust of wind suddenly detaches it from the surface on which it rests, the whole accumulation begins to move down, gently and quietly at first, and then with ever-increasing power and a deafening roar, uprooting trees, carrying away châlets and whatever happens to be in its course, and leaping like a huge stream of spray-covered water from precipice to precipice, till it makes one final bound across the valley, the impetus of its course frequently carrying it up for some distance on the opposite slope. The wind which accompanies such an avalanche is far more powerful than a raging hurricane, and it often levels trees and buildings, forces in windows and doors, and carries heavy objects to an incredible distance. One of the most remarkable performances I know of in connection with dust avalanches took place in the Engadine, when the wind preceding a huge mass of snow, rushing down the hill-side, blew five telegraph posts flat down, although the snow itself did not come within 500 feet of them.
“Constant readers” of the St. Moritz Post will remember that in an account of the avalanches of the winter of 1887-88 which appeared in the first number of the summer issue, it was stated that, on the occasion of the fall of two great avalanches into Saas-Grund, most of the windows and doors in the village were forced in from the pressure of air. While dealing with the subject of dust avalanches and the effects of the powerful wind which accompanies them, I may mention that Tschudi relates in his “Monde des Alpes” that such avalanches will sweep châlets and trees from the ground, and carry them, whirling like straws in a storm, through the air, dropping them at a distance of 400 feet. Châlets, filled with hay, and quite uninjured, have been found, it is said, some two hundred yards and more from the termination of the débris of an avalanche, the wind preceding which had blown them right across the valley.
In the year 1689 an enormous avalanche, which in the annals of the Grisons is spoken of as the most fearful one on record in the canton, came down from the heights above the village of Saas, in the Prättigau, and demolished 150 houses. Amongst the débris, which had been swept by the avalanche to a considerable distance, a rescue party discovered a baby lying safe and sound in his cradle, while six eggs were found uninjured in a basket close at hand.
Another sort of avalanche which can be roughly classed under the above heading is formed by the sudden descent of an overhanging mass of snow. The slightest movement in the air will often suffice to break the cornice, and it straightway comes rolling down the slope. Such avalanches are not usually much to be feared, though a notable exception to this fact was furnished on the Bernhardino Pass, when the mass of falling snow, overtaking the post in its passage, carried thirteen persons and a number of sledges over the precipice into the gorge beneath.
Dust avalanches are very frequently met with in summer after fresh snow by climbers amongst the higher peaks of the Alps-. It was an avalanche of this kind which caused the Matterhorn accident of 1887, and the account which Herr A. Lorria has given of the event is so realistic, and conveys so exactly to the mind what the nature of such an avalanche is, that I extract the following from the St. Moritz Post of January 28, 1888, for the benefit of my readers:—
“Gently from above an avalanche of snow came sliding down upon us; it carried Lammer away in spite of his efforts, and it projected me with my head against a rock. Lammer was blinded by the powdery snow, and thought that his last hour was come. The thunder of the roaring avalanche was fearful; we were dashed over rocks laid bare in the avalanche track, and leaped over two immense bergschrunds. At every change in the slope we flew into the air, and then were plunged again into the snow, and often dashed against one another. For a long time it seemed to Lammer as if all were over, countless thoughts were thronging through his brain, until at last the avalanche had expended its force, and we were left lying on the Tiefenmatten glacier. The height of our fall was estimated by the engineer Imfeldt at from 550 to 800 feet.”
In winter, when a fall of snow takes place on steep mountain-sides, scores of such avalanches may be seen dropping like shining threads down the cliffs. The face of the Eiger seen from Grindelwald in early spring is often fringed with tiny cascades of snow, while the rocks of the Wetterhorn[4] send down avalanches almost incessantly on the first sunny March morning after a snowfall.
The huge avalanches which, after a severe winter, summer visitors to Switzerland see lying in high Alpine valleys, covered with dust and stones, and with great trunks and branches of trees frozen into them, belong to the class of avalanches known as Grundlawinen, or compact avalanches. They usually fall from year to year in the same track, and come down, according to the warmth or severity of the season, during February and March. One year I saw a very large one fall in the Züge, near Davos-Platz, as late as the 3rd May.
In order for a really large compact avalanche to form, something more than the steep slope which is the birthplace of dust avalanches is necessary. The most dangerous formation of a hill-side, as regards compact avalanches, is the following. First, there must be, high up on the mountain, a collecting basin or valley, sloping somewhat downwards, in which a large amount of snow can accumulate. Secondly, leading from this basin must be a treeless slope, not too steep, on which snow will lie unless urged down by a considerable disturbance from above. In some seasons, when but little snow falls, no avalanche will take place under the conditions described. In others, when storm after storm has piled tons of snow in the upland valley, the warm, dry föhn wind will cause the mass to become detached from the earth on which it rests, and suddenly the entire winter’s store will come dashing down towards the valley, forming an avalanche such as visitors to the Engadine in the summer of 1888 saw in the Rosegthal and Beversthal.
These compact avalanches are composed, by the time they reach the end of their course, of stones, earth, roots and branches of trees, all frozen together by the heavy, wet snow in which they are encased. A story is told of a man who was overtaken on the Splügen by such an avalanche, and though he escaped from death, part of his coat was so firmly frozen into the icy mass, that he could not get it away. It is very remarkable that a person buried at a great depth in an avalanche of this kind can distinctly hear every word that those who are trying to find him may utter, though it is impossible for them to hear his cries.