Ice-Caves of France and Switzerland

by G. F. Browne

Mr. E.T. Holland visited the Surtshellir in the course of his tour in Iceland, in 1861, and an account of his visit is given in the first volume of 'Peaks, Passes, and Glaciers.'[^[112]] After following in Olafsen's steps for some time, the party reached a cave whose floor was composed of very clear ice, apparently of great thickness, for they could not see the lava beneath it. The walking on this smooth ice-floor Mr. Holland describes as being delightful, the whole sloping considerably downwards. 'In five minutes,' he continues, 'we reached the most beautiful fairy grotto imaginable. From the crystal floor of ice rose up group after group of transparent icy pillars, while from the glittering roof most brilliant icy pendants hung down to meet them. Columns and arches of ice were ranged along the crystalline walls ... I never saw a more brilliant scene; and indeed it would be difficult to imagine anything more fairy-like. The pillars were many of them of great size, tapering to a point as they rose. The largest were at least 8 feet high, and 6 feet in circumference at their base. The stalactites were on an equally grand scale. Through this lovely ice-grotto we walked for nearly ten minutes.'

ICE-CAVE IN THE SURTSHELLIR.

The temperature of the caves, Mr. Holland states in a note, was from 8° to 10° C. (46·4° to 50° F.), that of the air outside being 53·6° F.

The Gypsum Cave of Illetzkaya-Zastchita, in the Steppes of the Kirghis, South of Orenburg.

The district in which this cavern occurs is a small green oasis on the undulating steppe, lying on a vast bed of rock-salt, which extends over an area of two versts in length, and a mile in breadth, with a thickness of more than 100 feet. When the thin cover of red sand and marl is removed, the white salt is exposed, and is found to be so free from all stain, or admixture of other material, excepting sometimes minute filaments of gypsum, that it is pounded at once for use, without any cleansing or recrystallising process.

In the immediate neighbourhood of Illetzkaya-Zastchita there are two or three gypseous hillocks, and a cavern in one of these is used by the inhabitants as a cellar, having been artificially enlarged for that purpose. Sir Roderick Murchison and his colleagues visited this cavern on a hot day in August, with the thermometer at 90° in the shade, in the course of their travels under the patronage of the late Emperor of Russia.[^[113]] They found the hillock to be an irregular cone 150 feet in height; the entrance was by a frail door, on a level with the village street, and fully exposed to the rays of the sun; and yet, when the door was opened, so piercing a current of cold air poured forth, that they were glad to beat a retreat for a while; and on eventually exploring farther, they found the quass and provisions, stored in the cave, half-frozen within three or four paces of the door. The chasm soon opened out into a natural vault from 12 to 15 feet high, 10 or 12 paces long, and 7 or 8 in width, which seemed to have numerous small ramifications into the impending mound of gypsum and marl. The roof of this inner cavern was hung with undripping solid icicles, and the floor was a conglomerate of ice and frozen earth. They were assured that the cold is always greatest within when the external air is hottest and driest, and that the ice gradually disappears as winter approaches, and vanishes when the snow comes. The peasants were unanimous in these statements, and asserted that they could sleep in the cave without sheepskins in the depth of winter.

Sir Roderick Murchison and his friends were at first inclined to explain these phenomena by supposing that the chief fissure communicated with some surface of rock-salt, 'the saliferous vapours of which might be so rapidly evaporated or changed in escaping to an intensely hot and dry atmosphere as to produce ice and snow.' But Sir John Herschel, to whom they applied for assistance, rejected the evaporation theory, and suggested that the external summer wave of heat might possibly only reach the cave at Christmas, being delayed six months in its passage through the rock; the cold of winter, in the same manner, arriving at midsummer. To this the explorers objected, that the mound contained many caves, but' only in this particular fissure was any ice found. Dr. Robinson, astronomer at Armagh, endeavoured to explain the matter by referring to De Saussure's explanation of the phenomena of cold caves in Italy and elsewhere; but this, too, was considered unsatisfactory. At length, Professor Wheatstone referred them to the memoir by Professor Pictet, in the Bibliothèque Universelle of Geneva, where that savant improves upon De Saussure's theory, and applies it in its new form to the case of caves containing permanent ice, in tracts whose mean cold is above the freezing point. This they seem to have accepted, adding that the climatological circumstances of Orenburg--a wet spring, caused by the melting of the abundant snows, followed by a summer of intense and dry Asiatic heat--must be particularly favourable for the working out of the theory, and must also act powerfully in producing the refrigerating effects of evaporation.[^[114]]

The traveller Pallas visited Illetzkaya in July 1769, and describes this gypseous hillock.[^[115]] In his time the entrance by the side of the hill was unknown, as also was the existence of ice in the cavern. He saw at the top of the Kraoul-naï-Gora, or Watch-mountain, as it was called, a fissure which had once formed a large cavern, into which the Kirghis were in the habit of throwing furs and other materials as religious offerings. Although the cave had since fallen in, they still kept up a part of the ceremony, marching solemnly round the base of the hill once a year, and bathing in the neighbouring water. In earlier times, a man had descended through the fissure by means of cords, and found the cold within insupportable, having very probably reached the present ice-cave.

Pallas describes many caves in various parts of Russia, but never seems to hint at the existence of ice in them, though he specially mentions their extreme cold. Some of these occurred in gypsum, and some in limestone; and the gypseous caves showed universally a very low temperature, though still far above the freezing-point.[^[116]]: Thus in the dark cavern of Barnoukova,[^[117]] on the Piana, in a rock of gypsum, while the thermometer in the shade stood at 75°•2, the temperatures at various points in the cave were,--at the entrance 59°•36, 25 feet from the entrance 46°•4, and in the coldest part 42°•8. This cold he describes as insupportable. The temperature of the water which had accumulated in the coldest parts of the cave was 48°•8, considerably higher than the surrounding atmosphere; from which Pallas concluded that the cold of gypsum-caves is due to the acid vapours which are generally observed in grottoes of this description. In May 1770, he found snow on the sloping entrance to the cavern of Loeklé, in the neighbourhood of the Oufa; but the air of the interior was not colder than was to be expected in a deep cave.