There are vast ravines and valleys among the higher Alps where the snow accumulates, being driven into them by the winds and storms in the winter, and sliding into them, in great avalanches, in the spring. These vast depositories of snow become changed into ice below the surface; for at the surface there is a continual melting, and the water, flowing down through the mass, freezes below. Thus there are valleys, or rather ravines, some of them two or three miles wide and ten or fifteen miles long, filled with ice, transparent, solid, and blue, hundreds of feet in depth. They are called glaciers. And what is most astonishing in respect to these icy accumulations is that, though the ice is perfectly compact and solid, the whole mass is found to be continually in a state of slow motion down the valley in which it lies, at the rate of about a foot in twenty-four hours. By standing upon the surface and listening attentively, we hear, from time to time, a grinding sound. The rocks which lie along the sides are pulverized, and are continually moving against each other and falling; and then, besides, which is a more direct and positive proof still of the motion of the mass, a mark may be set up upon the ice, as has been often done, and marks corresponding to it made upon the solid rocks on each side of the valley, and by this means the fact of the motion, and the exact rate of it, may be fully ascertained.
Thus these valleys are really and literally rivers of ice, rising among the summits of the mountains, and flowing, slowly it is true, but with a continuous and certain current, to a sort of mouth in some great and open valley below. Here the streams which have flowed over the surface above, and descended into the mass through countless crevices and chasms, into which the traveler looks down with terror, concentrate and issue from under the ice in a turbid torrent, w hick comes out from a vast archway made by the falling in of masses which the water has undermined. This lower end of the glacier sometimes presents a perpendicular wall hundreds of feet in height; sometimes it crowds down into the fertile valley, advancing in some unusually cold summer into the cultivated country, where, as it slowly moves on, it plows up the ground, carries away the orchards and fields, and even drives the inhabitants from the villages which it threatens. If the next summer proves warm, the terrible monster slowly draws back its Rigid head, and the inhabitants return to the ground It reluctantly evacuates, and attempt to repair the damage it has done.
The Alps lie between France and Italy, and the great valleys and the ranges of mountain land lie in such a direction that they must be crossed in order to pass from one country to the other. These ranges are, however, not regular. They are traversed by innumerable chasms, fissures, and ravines; in some places they rise in vast rounded summits and swells, covered with fields of spotless snow; in others they tower in lofty, needle-like peaks, which even the chamois can not scale, and where scarcely a flake of snow can find a place to rest. Around and among these peaks and summits, and through these frightful defiles and chasms, the roads twist and turn, in a zigzag and constantly ascending course, creeping along the most frightful precipices, sometimes beneath them and sometimes on the brink, penetrating the darkest and gloomiest defiles, skirting the most impetuous and foaming torrents, and at last, perhaps, emerging upon the surface of a glacier, to be lost in interminable fields of ice and snow, where countless brooks run in glassy channels, and crevices yawn, ready to take advantage of any slip which may enable them to take down the traveler into their bottomless abysses.