[Footnote 105: _Reise durch Island_, Copenhagen, 1744 (being a German translation from the original Danish), i. 128 sqq.]
[Footnote 106: _Henderson"s Iceland_, ii. 189 sqq.]
[Footnote 107: Pp. 145 sqq.]
[Footnote 108: The Sturlunga, Landnama, and Holmveria Sagas.]
[Footnote 109: Two priests determined to solve the mystery of this unapproachable valley, the Aradal, or Thoris-thal, with its rich meadows and gigantic inhabitants, and made an expedition for this purpose in 1664. They reached a point where the glaciers fell off into a valley so deep that they could not see whether there were meadows at the bottom or not, and the slope was so rapid that it was impossible to descend.]
[Footnote 110: _Voyage en Islande; Atlas Historique_; t. ii., pl.
130-133.]
[Footnote 111: _Iceland: its Scenes and Sagas_: pp. 97, 98.]
[Footnote 112: Page 113.]
[Footnote 113: _Russia and the Ural Mountains_, i. 186, sqq.]
[Footnote 114: See the Papers read before the Geological Society of London, on March 9, 1842, by Sir John Herschel and Sir E. Murchison, the substance of which has been given above.
See also the _Edinburgh Philosophical Journal_ for 1843 (x.x.xv. 191), for an attempt by Dr. Hope to explain the phenomena of this cave by a reference to the slow penetration of the winter and summer waves of cold and heat. Dr. Hope believes that, although the external changes do not travel to any great depth, they reach far enough to communicate with some of the fissures leading to the cave.]
[Footnote 115: _Voyages_ (French translation); Paris, 1788; i. 364.]
[Footnote 116: In the gypsum to the NE. of Kungur, on the banks of the Iren, there is a cave containing ice. Four of its chambers have ice, in one of which a stalagmite of ice rises almost to the roof. The farthest chamber, 625 fathoms from the entrance, contains a lake of water which stretches away out of sight under the low roof. (_Taschenbuch fur die gesammte Mineralogie_; Leonhard, 1826; B. 2, S. 425. Published as _Zeitschrift fur Mineralogie_.)]
[Footnote 117: Pallas, _Voyages_, i. 84.]
[Footnote 118: _Teneriffe_, by Professor Smyth, ch. viii., and Humboldt, _Voyage aux Regions equinoctiales_; Paris, 1814; i. 124.]
[Footnote 119: They afterwards discovered smoke issuing from the centre of this patch of stones; so that volcanic heat may possibly have had something to do with the disappearance of the snow.]
[Footnote 120: "_Ce pet.i.t glacier souterrain_," Humboldt, l.c.]
[Footnote 121: See p. 272 for an account of the underground glacier in the neighbourhood of the Casa Inglese.]
CHAPTER XVI.
BRIEF NOTICES OF OTHER ICE-CAVES.[122]
On the Brandstein in Styria, in the district of Gems, there is an ice-hole closely resembling some of the glacieres of the Jura. It is described by Sartori,[123] as lying in a much-fissured region, reached after four hours of steep ascent from the neighbouring village, through a forest of fir. Some of the fissures contain water and some snow, while others are apparently unfathomable. From one of the largest of these, a strong and cold current blows in summer, and in this fissure is the ice-hole. Sartori found _crimpons_ necessary for descending the frozen snow which led from the entrance to the floor of the cave, where he discovered pillars and capitals and pyramids of ice of every possible shape and variety, as if the cave had contained the ruins of a Gothic church, or a fairy palace. At the farther end, after pa.s.sing large cascades of ice, his party reached a dark grey hole, which lighted up into blue and green under the influence of the torches; they could not discover the termination of this hole, and the stones which they rolled down into it seemed to go on for ever. The greatest height of the cave is about 36 feet, and its length 192 feet, with a maximum breadth of 126 feet. Towards the end of autumn, the temperature of the ice-hole rises so much, that the glacial decorations disappear, and various wild animals are driven by the cold of winter to take shelter in the comparative warmth of the cave. The elevation of the district in which this ice-hole occurs is about 1,800 German feet above the sea.
In Upper Styria, where the Frauenmauer overlooks the basin in which the mining town of Eisenerz is situated, an ice-cave has been explored, and a description of it has been given by certain members of the Austrian Alpine Club.[124] The Brandstein is spoken of as one of the peaks in the immediate neighbourhood; and as the cave previously described is stated by Sartori to be on the Brandstein, that district would seem to be rich in glacieres. The cavern is most easily explored from Eisenerz, and on that side the entrance is 4,539 Vienna feet above the sea. Its other outlet, in the Tragoss valley, is 300 feet higher. The total length of the cave is 2,040 Vienna feet. After pa.s.sing the entrance, which is an archway from 12 to 18 feet high, the main course of the cave is soon left, and a branch is followed which leads to the _Eis-kammer_. This ice-chamber consists of a grotto from 30 to 40 fathoms long, decked with ice-crystals, pillars of ice, and cascades of the same material, the floor being composed of ice as smooth as gla.s.s. In the summer, pleasure-parties a.s.semble in the cave and amuse themselves with the game of _Eisschiessen_, so popular in Upper Styria as a winter diversion. The hotter the summer, the more ice is found in the Eiskammer, and the general belief is that it all disappears in winter.
The cave proper, which a.s.sumes stupendous dimensions in its long course, shows no ice. It seems to be formed in the Muschelkalk of the Trias formation, and so far no limestone stalact.i.tes have been discovered. It has not, however, as yet been fully explored. The editor of the proceedings of the Austrian Alpine Club gives a reference to Scheiner, "_Ausflug nach der Hohle der Frauenmauer," (Steiermarkische Zeitschrift, neue Folge_, i. 2, 1834, p. 3.)
At Latzenberg, near Weissenstein in Carniola, there is another ice-cave, described by Rosenmuller.[125] It is entered by a long dark pa.s.sage in which are pillars of ice arranged like the pipes of an organ, varying from the thickness of a man"s body to the size of a straw. All these are said to melt in winter. Farther on are two other pa.s.sages, one of which pa.s.ses upwards over _Stufe_, and is coated in summer with ice; the other has not been explored.
Near Glaneck in the Untersberg, not far from Salzburg, is a cave called the Kolowrathohle, of which a description is given by Gumbel in his great geological work on the Bavarian Alps.[126] It is a s.p.a.cious cavern, opening in a steep wall of rock above the _Rositenschlucht_ between the Platten and _Dachstein-kalk._[127] An ice-current rushes from within, and ice is found on the threshold, becoming more prevalent in the farther recesses of the cave. The lower parts are tolerably roomy, and ma.s.ses of ice of various shapes are found piled one upon another, lighting up with magical effect when torches are brought to bear upon them. Gumbel believes that the cold currents which stream into the cave from the numerous fissures in its walls are the cause of the ice; and though this is the only known ice-cave far and near, he imagines that the icy-currents which are frequently met with in that district, and in the _Hochgebirge_, would be found to proceed in reality from like caves, if the fissures from which they blow could be penetrated.
Behrens[128] describes two ice-caves near Questenberg, in the county of Stollberg, on the Harz mountains. They both occur in limestone, and are known as the Great and Little Ice-holes. The one is close to the village of Questenberg, and consists of a chasm several fathoms deep, so cold that in summer the water trickling down its edges is frozen into long icicles. The opening is large and faces due south, and yet the hotter the day the more ice is found; whereas in winter a warm steam comes out, as if from a stove. The other cave is farther into the mountain; it is s.p.a.cious and light, and very cold in summer.
In Gehler"s _Physik. Worterbuch_ (Art Hohle), a small hole is mentioned near Dole, which is said to be remarkable for the large and curiously-shaped icicles found there; but no sufficient account of it seems to have been given.
An ice-hole is also spoken of in the same article, which occurs on the east side of the town of Vesoul.[129] The hole is described as being small, with a little rivulet of water: this water, and also that which trickles down the walls of the cave, is converted into ice, and so much is formed on a cold day that it requires eight warm days to melt it.
Gollut, in his description of the _fre-puits_ of Vesoul,[130] observes that the remarkable pit known by that name was so cold, that in his time it had never been fully explored. Gehler"s expression, however, "a small hole," cannot possibly apply to the _fre-puits_; so that these would seem to be two different examples of cold caves near Vesoul.
There is an interesting account in Poggendorff"s Annalen[131] of a visit made by Professor A. Pleischl to a mountain in the circle of Leitmeritz, where ice is found in summer under very curious circ.u.mstances. The mountain is called Pleschiwetz, and lies above Kameik, in Bohemia, not far from the town of Leitmeritz. On the 24th of June in each year, large numbers of pilgrims a.s.semble at the romantic chapel of S. John the Baptist in the Wilderness; and it is a part of their occupation to search for ice under the basaltic rocks, and carry it home wrapped in moss, as a proof that they have really made the pilgrimage. Professor Pleischl visited this district at the end of May 1834. The weather was hot for the season, as had been the case in April also, and there had been very little snow in the winter. A path leads from the chapel of S.
John through the woods which deck the Pleschiwetz, and then over a small plain to the foot of the basaltic rocks. Here the mountain slopes away very steeply to the south, and the slope is thickly strewn with basaltic _debris_. From east to west this slope measures about 40 fathoms, and its length is about 70 fathoms. It is surrounded on both sides and at the foot by trees and shrubs. The sun burned so directly on to the _debris_, that the basaltic blocks were in some cases too hot to be touched by the naked hand.
Professor Pleischl spent three hours of the early afternoon on this spot. The upper surface of the basaltic blocks had a temperature of at least 122 F. The presence of an icy current was detected by inserting the hand into the lower crevices; and on removing the loose stones to a depth of 1-1/2 or 2 feet, ice was found in considerable quant.i.ties. On the 27th of August, he proceeded to make a further investigation of this phenomenon; but he found the temperature of the blocks only 106 F., and in the crevices, at a depth of 2 or 3 feet, the lowest temperature reached was 3875 F. The external temperature in the shade was at the same time 83 F.
A third visit, in January 1835, gave no results; but on January 21, 1838, the Professor succeeded in determining some very remarkable facts. A depression in the sloping plain is called, _par excellence_, the ice-hole; and this is surrounded by firs and birches, which grow within three or four fathoms of the edge of the hole, so that the rays of the sun do not reach the hole in winter. Fresh snow lay on these trees; and there was nowhere any sign of melted snow, or of the formation of icicles. The basaltic _debris_, in which ice had been found in the summer, covers here a s.p.a.ce of 5 fathoms long by 3 or 4 broad, immediately at the foot of a steep basaltic precipice. At eleven in the morning the temperature was 14 F. in the shade; and snow lay all round the ice-hole, to a thickness of 1-1/2 or 2 feet.
The snow which covered the _debris_ was pierced by holes, which could not have been caused by the sun, for its rays did not penetrate the trees; and, indeed, no sun had been visible for some days. These holes were generally turned towards the north, and were like chimneys. On investigation, it was found that icicles hung down into them, showing, of course, past or present thaw, and within the cavities no ice was found. The thermometer gave here from 275 F. to 2515 F.; but in the crevices, into which the thermometer could not be pushed, the hand discovered a warm air. The moss drawn from these crevices was found to be steeped in unfrozen water, and it froze promptly when brought into the outer air.
The party afterwards climbed up the precipitous basalt, and reached, at 3 P.M., a level covered with large blocks of the same material, where the thermometer was slightly under 12 F. in the shade. The blocks were for the most part stripped of snow, and in some cases thin shields of ice were observed standing out two or three inches from them, forming hollow chambers, in which an agreeable warmth was found. These shields were invariably on the south side of the stones, the north side being free from ice and snow alike. In some places vapours were seen to rise.
The thermometer gave 41 F. at a depth of six inches among the stones, though the external temperature, as has been said, was 12 F. For eight days previously, the thermometer had been always far below the freezing point, and on the 17th (four days before) had been 13 below zero (F.).
On the 19th and 20th heavy snow had fallen. All these facts seem to show that the warmth which had caused the chimneys in the snow over the ice-holes, and the heated vapours on the higher parts of the mountains, proceeded from within, and not from without.
The people of the district a.s.sured Professor Pleischl that the hotter the summer, the more ice is formed; and that it disappears when the nights become long and the days short. Dr. Weiss, for six years head of the Gymnasium of Leitmeritz, stated that when one of the holes was emptied of ice in the summer, it filled again in a few days. The explanation given by the Professor of this phenomenon is, that the blocks of basalt, that being an excellent conductor of heat, pa.s.s so much warmth through to their under surfaces--which form the roof of small chambers filled with a spongy ma.s.s of decaying leaves--that the rapid evaporation thereby caused produces the cold air and the ice. He omits to explain why there should be anything exceptional in the winter phenomenon of the crevices among the stones.
There are two other places in Bohemia where ice is found in summer. One is on the Steinberg, in the county of Konaged;[132] it is a small basin, surrounded by trees, where, in the middle of summer, lumps of ice are found under basaltic _debris_. This ice is only formed, according to Sommer, in the hottest part of the year. The other is on the Zinkenstein, one of the highest points of the Vierzehnberg, in the circle of Leitmeritz. It is described by Sommer[133] as a cleft, five fathoms deep, in the basaltic rock, where ice is found in the hottest seasons. Professor Pleischl put this a.s.sertion to the test by visiting the spot in the end of August, when he found no signs of ice.
Another writer in Poggendorff[134] describes a somewhat similar appearance on the Saalberg. Here ice is found on the surface from June to the middle of August; and that, too, with a west exposure and in moderate shade. In July, the ice was so abundant that it could be seen from some distance: it was half a foot thick, and yielded neither to sun nor rain. In the middle of August there was no ice on the surface; but when the loose _debris_ was removed, the most beautiful ice appeared, and at a little depth all was frozen as hard as if it had been the depth of winter.[135] The people who work in the neighbourhood declare that the place remains open, and free from ice or snow, in the greatest cold, and that no ice begins to form till the month of June. When the writer of the account in Poggendorff visited the ice-hole, the peasants were in the habit of carrying large ma.s.ses of ice down to their houses, through a temperature of 81 F.
Reich[136] gives a detailed and valuable account of the prevalence of subterranean ice on the Sauberg, a hill which forms one side of a ravine near Ehrenfriedersdorf. The surface is about 2,000 feet above the sea, and its mean temperature, as determined by many careful observations, about 45 F. There are several tin-mines in this district, and the extended observations made by the authorities establish the curious fact that the mean temperature is considerably lower beneath than at the surface. For instance, in the S. Christoph pit, it is found that the mean temperature, at 15 fathoms below the surface, is only slightly above 42 F.; while at the Morgenrother cross-cut the same mean temperature is found at a depth of 46 fathoms. The annual change of temperature is very small in these mines, and the maximum and minimum are reached very late; so that, if a point could be found with a mean temperature of 32 F., ice would increase there up to June or even July, and then diminish until December or January; in which case the phenomenon so often said to be observed in connection with subterranean ice--the melting in winter and forming in summer--would really be presented.
The ice on the Sauberg is frequently found to commence at a depth of 3 or 4 fathoms, and in the years 1811 and 1813 it extended to 24 fathoms below the surface: this depth, however, was exceptionally great, and as a rule the limit is reached at about 14 fathoms.[137] The ice is usually not very firm, and can be broken by stout blows with a stick; but between the years 1790 and 1800, when it was found at a depth of from 3 to 9 fathoms, it was so hard that blasting became necessary, and at that time the miners were with difficulty protected from the effects of the severe cold. The greatest quant.i.ty of ice is found in the interstices of the rubbish-beds of old workings, and here it a.s.sumes a crystalline form, the rocks being covered with a "fibrous" structure, arranged perpendicularly to their surface.
Reich reports the universal presence of cold currents of air in these shafts and mines, and, in consequence, takes the opportunity of contradicting a statement in Horner"s _Physik. Worterbuch,_[138] that the absence of all current of air is essential to the formation of subterranean ice. He quotes the case of the cheese-caves of Roquefort as a further confirmation of his own observations with regard to the connection between ice in caves and cold currents of air; but of the many accounts which I have met with of the curious caves referred to, both in books and from the lips of those who have visited them, not one has made any mention of ice.[139] He states, too, that when the strength of the current is diminished, its temperature is increased; a fact which all observations of the cold currents in caves, especially those made with so much care by M. Saussure, abundantly establish.
In the way of explanation, Reich mentions the possibility of rocks of peculiar formation possessing actually a low degree of temperature;[140]
but he rejects this suggestion, preferring to believe that in some cases the cold resulting from evaporation is the cause of ice, and in others the greater specific gravity of cold as compared with warmer air.
In the _Bulletin des Sciences Naturelles_,[141] it is stated that a large quant.i.ty of ice is found in one of the recesses of the grotto of Antiparos--a fact which I have not seen mentioned elsewhere. After penetrating a long way through difficult fissures, a square chamber is at length reached, measuring 300 feet in length and breadth, with a height of about 80 feet. The walls and roof and floor are beautifully decorated with ice, and reflect all the colours of the rainbow. There are groups of pyramidal and round columns, and in some parts of the cave screens or curtains of ice 10 or 12 feet broad hang down to the floor.
In a later volume of the same periodical,[142] there is a description of a hill in Virginia where ice is found in summer. This hill lies near the road between Winchester and Romney, on the North River, lat.i.tude 39 N.
One side of the hill is entirely composed of loose stones from ten to twenty pounds in weight, and under these the ice is found, although their upper surface is exposed to the full sun from 9 or 10 A.M. till sunset. In all seasons there is an abundance of ice. A writer in the "London and Paris Observer"[143] visited the spot on the 4th of July, after a time of stifling heat, and in ten minutes he found more ice than the whole party could have carried away. He did not explore any farther than the foot of the hill; but the neighbours, who used the ice regularly in summer, a.s.sured him that it was to be found high up also.
A constant and strong current issued from the crevices, stronger and infinitely colder than the current in the famous "blowing cave" of Virginia. A man had built a store-room for meat within the influence of one of these currents, and hard dry icicles were seen hanging from the wooden supports inside: the flies, too, which had been attracted by the meat, were found frozen on to the stones. This is not the only district where ice is found within temperate lat.i.tudes in North America. In Professor Silliman"s "American Journal of Science,"[144] in a sketch of the geology of the township of Salisbury, Con. (lat.i.tude 43 N.), "natural ice-houses" are mentioned. These consist of chasms of considerable extent in the mica-state, where ice and snow remain during the greater part of the year. The princ.i.p.al of these chasms lies in the east part of the town, and is several hundred feet long, sixty feet deep, and about forty wide. The slate is of a very compact kind; and the walls are perpendicular, and correspond with much exactness. At the bottom is a cold spring, and a cave of considerable extent, in which it is probable that the ice lies--for the writer does not specify the position in which it is found. The chasm is a favourite retreat in summer, and is called the Wolf-hollow, from its having formerly been a famous haunt for wolves.
Similar receptacles for summer-ice are found in several places in North America. In the forty-ninth volume of the _Sitzungsberichte der Kaiserl.
Akademie in Wien_ (1te. Abth.), a list of references to various ice-holes is appended to a paper by Dr. Boue on the geology of Servia.