Ice-Caves of France and Switzerland

by G. F. Browne

While we were in the cave, we noticed that the surfaces of the columns were covered by very irregular lines, marked somewhat deeply in the ice, and dividing the surface into areas of all shapes, a sort of network, with meshes of many different shapes and sizes. These areas were smaller towards the edges of the columns; the lines containing them were not, as a rule, straight lines, and almost baffled our efforts to count them, but, to the best of my belief, there were meshes with three, four, and up to eight sides. The column which stood clear of the rock was composed of very limpid ice, without admixture of air; but the cascades were interpenetrated by veins of looser white ice, and, where the white ice came, the surface lines seemed to disappear. As we sat on the grass outside, arranging our properties for departure, my attention was arrested by the columnar appearance of the fractured edge of the block of ice which we had used at luncheon. It was about 5 inches thick, and had formed part of a stalagmite whose horizontal section, like that of the free column, would be an ellipse of considerable eccentricity; and, on examination, it turned out that the surface areas, which varied in size from a large thumb-nail to something very small, were the ends of prisms reaching through to the other side of the piece of ice, at any rate in the thinner parts, and presenting there similar faces. Not only so, but the prisms could be detached with great ease, by using no instrument more violent than the fingers; while the point of a thin knife entered freely at any of the surface lines, and split the ice neatly down the sides of the prisms. When one or two of the sides of a prism were exposed, at the edge of the piece of ice, the prism could be pushed out entire, like a knot from the edge of a piece of wood. In some cases there seemed to be capillary fissures coincident with the lines where several sides of prisms met. Considering the shape of the whole column, it is clear that the two ends of each prism could not be parallel; neither was one of the ends perfectly symmetrical with the other, and I do not think that the prisms were of the nature of truncated pyramids. On descending again, I found that the columns were without exception formed of this prismatic ice, either in whole, as in the clear column, or in part, as where limpid prisms existed among the white ice which ran in veins down the cascades. In the free vertical column the prisms seemed to be deposited horizontally, and in the thicker parts they did not pass clear through. We carried a large piece of ice down to Arzier in a botanical tin, and on our arrival there we found that all traces of external lines had disappeared.

This visit to the glacière was on Saturday, and on the following Monday I determined to go up alone, to take a registering thermometer, and leave it in the cave for the night; which, of course, would entail a third visit on the next day. Monday brought a steady penetrating rain, of that peculiar character which six Scotch springs had taught me to describe as 'just a bit must;' while in the higher regions the fog was so hopeless, that a sudden lift of the mist revealed the unpleasant fact that considerable progress had been made in a westerly direction, the true line being north-west. Instead of the rocks of La Genollière, the foreground presented was the base of the Dôle, and the chasm which affords a passage from the well-known fortress of Les Rousses into Vaud. There was nothing for it but to turn in the right direction, or attempt to do so, and force a way through the wet woods till something should turn up. This something took the form of a châlet; but no amount of hammering and shouting produced any response, and it was only after a forcible entrance, and a prolonged course of interior shouting, that a man was at length drawn. He said that he had been asleep--and why he put it in a past tense is still a mystery--and could give no idea of the direction of the châlet on La Genollière, beyond a vague suggestion that it was somewhere in the mist; a suggestion by no means improbable, seeing that the mist was ubiquitous. One piece of information he was able to give, and it was consoling: I was now, it seemed, on the Fruitière de Nyon, and therefore the desired châlet could not be far off, if only a guide could be found. On the whole, he thought that a guide could not be found; but there were men in the châlet, and I might go up the ladder with him and see what could be done. He led to a chamber with a window of one small pane, dating apparently from the first invention of glass, and never cleaned since. An invisible corner of the room was appealed to; but the voice which resided there, and seemed like everything else to be asleep, pleaded dreamily a total ignorance of the whereabouts of the châlet in question. Just as, by dint of steady staring through the darkness, an indistinct form of a mattress, with a human being reclining thereon, began to be visible, another dark corner announced that this new speaker had heard of a p'tit sentier leading to the châlet, but knew neither direction nor distance. Here the space between the two corners put in a word; and, as the darkness was now becoming natural, seven or eight mattresses appeared, ranged round the room, some holding one, some two men, most of whom were sitting up on end with old caps on, displaying every variety of squalor. The voice which had spoken last declared that the distance was three-quarters of an hour, and that if the day were clear there would be no difficulty in reaching the châlet; as it was, the man would be very glad to try.

A change of cap was the only dressing necessary for the volunteer, and we faced the fog and rain, which elicited from him such a disgraceful amount of swearing, that it was on all accounts well when the rain ceased for a few minutes, the mists rolled off, and the clouds lifted sufficiently to betray the surface of the Lake of Geneva, luxuriating in the clear warmth of an early summer's day, and making us shiver by the painful contrast which our own altitude presented. The deep blue of the lake brought to mind the story of the shepherd of Gessenay (Saanen), of whom it is told that when he was passing the hills with some friends for a first visit to Vevey, and came in sight of the lake, which he had never seen before, he turned and hurried home incontinent, declaring that he would not enter a country where the good God had made the blue sky to fall and fill the valleys.

In this bright interval we came upon a magnificent fox, and the peasant's impulse was, 'Oh, for a good gun!' an exclamation which would have sounded horrible to English ears, if I had not been previously broken in to it by an invitation from a Scotch gamekeeper to a fox-hunt, when he promised an excellent gun, and a stance which the foxes were sure to pass.

The rain now came on again, and the guide thought he had had plenty of it, and must return for the afternoon milking; and just then, as good luck would have it, we stumbled upon an immense clump of nettles which had been one of our landmarks two days before, so that he was no longer necessary, and we said affectionate adieux.

The glacière was in a state of ruin. Only the right-hand column, not speaking heraldically, was standing, the others lying in blocks frozen hard together on the ground. The column which still stood was much shrunken, and seemed too small for its fissure, the sides of which it scarcely touched. The wind blew down the entrance slope so determinedly, that a candle found it difficult to live at the bottom of the first cave; and a portion of the current blew into the glacière, and in its sweep exactly struck the fallen columns, the edges of which were already rounded by thaw. Much of this must be attributed to the recent opening of the second shaft (p. 5), which admits a thorough draught through the first cave, and so exposes the glacière to currents of warmer air; and I should expect to find that in future the ice will disappear from that part of the cave every summer, [^[7]] whereas in 1861 we found it thick and dry (excepting a few small basins containing water) and evidently permanent, in the middle of a very hot August. The low part of the cave was so completely protected from the current, that the candle burned there quite steadily for an hour and a half: still, like the others, the column at that end of the glacière was broken down, and it therefore became necessary to attribute its fall to some other agency than the current of external air. There had been a very large amount of rain, and the surface of the rock in the fissures was evidently wet; so I have no doubt that the filtering through of the warm rain-water had thawed the upper supports of the ice-cascades, and then, owing to their slightly inclined position, the pedestal had not provided sufficient support, and so they had fallen. One of them, perhaps, had brought down in its fall the free column, which had stood two days before on its own base, without any support from the rock. Very probably, too--indeed, almost certainly,--the fall of the large mass of rock, which once formed the bottom of the basin on the north side of the road, has affected the old-established fissures, by which rain-water has been accustomed to penetrate in small quantities to the glacière, so that now a much larger amount is admitted. On this account, there will probably be a great diminution of the ice in the course of future summers, though the amount formed each winter may be greater than it has hitherto been. Constant examination of other columns and fissures has convinced me, that, before the end of autumn, the majority of the glacières will have lost all the columns which depend upon the roof for a part of their support, or spring from fissures in the wall; whereas those which are true stalagmites, and are self-supporting, will have a much better chance of remaining through the warm season, and lasting till the winter, and so increasing in size from year to year. Free stalagmites, however, which are formed under fissures capable of pouring down a large amount of water on the occasion of a great flood of rain, must succumb in time, though not so soon as the supported columns.

A curious appearance was presented by a small free stalagmite in the retired part of the cave. The surface of the stalagmite was wet, from the drops proceeding from a fissure above, and was lightly covered in many parts with a calcareous deposit, brought down from the fissures in the roof by the water filtering through. The stalagmite was of the double-edged-sword shape, and the limestone deposit collected chiefly at one of its edges, the edge nearer to that part of the cave where thaw prevailed; so that the real edge was a ridge of deposit beyond the edge of the ice.[^[8]] Patches of limestone paste lay on many parts of the ice-floor.

In the loftier part of the cave, water dropped from the roof to so large an extent, that ninety-six drops of water in a minute splashed on to a small stone immediately under the main fissure. This stone was in the centre of a considerable area of the floor which was clear of ice; and it struck me that if the columns were formed by the freezing of water dropping from the roof, there ought to have been at some time a large column under this, the most plentiful source of water in the cave. Accordingly, I found that the edge of the ice round this clear area was much thicker than the rest of the ice of the floor, and was evidently the remains of the swelling pedestal of a column which had been about 12 feet in circumference. This departed column may account for a fact which I discovered in another glacière, and found to be of very common occurrence, viz., that in large stalagmites there is a considerable internal cavity, extending some feet up from the ground, and affording room even for a man to walk about inside the column. When the melted snows of spring send down to the cave, through the fissures of the rock, an abundance of water at a very low temperature, and the cave itself is stored with the winter's cold, these thicker rings of ice catch first the descending water, and so a circular wall, naturally conical, is formed round the area of stones; the remaining water either running off through the interstices, or forming a floor of ice of less thickness, which yields to the next summer's drops. In the course of time, this conical wall rises, narrowing always, till a dome-like roof is at length formed, and thenceforth the column is solid. Of course, the interior cannot be wholly free from ice; and it will be seen from the account of one of these cavities, which I explored in the Schafloch, that they are decked with ice precisely as might be expected. [^[9]] Another possible explanation of this curious and beautiful phenomenon will be given hereafter.[^[10]]

The temperature was half a degree lower than when there were three of us in the cave two days before. I deposited one of Casella's registering thermometers, on wood, on a stone in that part of the floor which was free from ice, though there was ice all round it at some little distance. The thermometer was well above the surface of the ice, and was protected from chance drops of water from the roof.

The next morning I started early from Arzier, having an afternoon journey in prospect to the neighbourhood of another glacière, and was accompanied by Captain Douglas Smith, of the 4th Regiment. On our way to La Genollière, we came across the man who had served as guide the day before, and a short conversation respecting the glacière ensued. He had only seen it once, many years before, and he held stoutly to the usual belief of the peasantry, that the ice is formed in summer, and melts in winter; a belief which everything I had then seen contradicted. His last words as we parted were, 'Plus il fait chaud, plus ça gèle;' and, paradoxical as it may appear, I believe that some truth was concealed in what he said, though not as he meant it. Considering that his ideas were confined to his cattle and their requirements, and that water is often very difficult to find in that part of the Jura, a hot summer would probably mean with him a dry summer, that is, a summer which does not send down much water to thaw the columns in the cave. Extra heat in the air outside, at any season, does not, as experience of these caves proves abundantly, produce very considerable disturbance of their low temperature, and so summer water is a much worse enemy than extra summer heat; and if the caves could be protected from water in the hot season, the columns in them would know how to resist the possible--but very small--increase of temperature due to the excess of heat of one summer above another. And since the eye is most struck by the appearance of the stalagmites and ice-cascades, it may well be that the peasants have seen these standing at the end of an unusually hot and dry summer, and have thence concluded that hot summers are the best time for the formation of ice. Of course, at the beginning of the winter after a hot summer, there will be on these terms a larger nucleus of ice; and so it will become true that the hotter the year, the more ice there will be, both during the summer itself and after the following winter.