ON THE LAND. 223 



little more than an eighth of the mass makes its appearance 

 above the surface, one can readily form some conception of 

 the bulk and weight of a " berg," and of its crushing and 

 grinding power when drifted along at the rate of four or 

 five miles an hour. But the ice that was generated on 

 and has now become ice on water, and belongs to the next 

 division of our subject. 



But before taking leave of ice as it appears on the land, 

 there is another condition in which it not unfrequently 

 occurs, and which is well deserving of the attention of the 

 geologist and hydrographer. We allude to its formation 

 and conservation in caverns and fissures where it may have 

 lain unchanged for ages. These ice-caves, as they are called, 

 are found in many countries, and most abundantly, of 

 course, in all high, dry, and cold regions. In some the ice 

 appears in stalactitic and stalagmitic masses, issuing from 

 the roofs in fantastic cascades and wall-like screens, or rest- 

 ing on the floor in cones and pillars ; in some it merely 

 forms a pavement of varying thickness ; while in others it 

 glitters on all sides like a casing of the purest alabaster. 

 Palseontologically, the preservative effects of such cavern ice 

 must be very great; hydrographically, its partial melting 

 in summer may feed the mountain-springs that would other- 

 wise be dry; and economically, it yields to the surrounding 

 districts its cooling and refreshing supplies. In Europe 

 the better-known ice-caves or glacieres, as they are locally 

 termed, occur in France and Switzerland, and those form 

 the subject of a recent volume by the Eev. G. F. Browne, 

 a perusal of which will well repay the reader.* As the 

 subject is somewhat novel, the theory of their formation, 

 as given by Deluc and the author, may prove instructive ; 

 and this we present with a little condensation : 



" The heavy cold air of winter," says Mr Browne, " sinks 

 * 'Ice- Caves of France and Switzerland.' Longmans & Co. 1865. 



