[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 (xxxv. 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 für die gesammte Mineralogie_; Leonhard, 1826; B. 2, S. 425. Published as _Zeitschrift für Mineralogie_.)] [Footnote 117: Pallas, _Voyages_, i. 84.] [Footnote 118: _Teneriffe_, by Professor Smyth, ch. viii., and Humboldt, _Voyage aux Régions Équinoctiales_; 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 petit 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]