<-> MOUNTAINS. 



of sparry deposit. The floor grew up under the droppings into 

 fantastic heaps of stalagmite, which, sometimes reaching the pipes, 

 united roof and floor by pillars of exquisite beauty. 



To a marvellous specimen of this kind the ' Pillar Hall ' owes 

 its name. When the Cave was opened, its floor was very uneven, 

 and many little pools were found in hollows of the rock or in 

 basins, guarded by walls of stalagmite. These pools remain as 

 they were found. The sides of these basins are usually undu- 

 lated stalagmite, and there is often a bright sheet of this sparry 

 deposit spreading widely from the side over the surface of the 

 water like a sheet of snowy ice or the leaf of a crystal plant, 

 narrowing the area of these fairy lakes. The explanation of this 

 is simple. The water charged with calcareous matter, and trick- 

 ling down the stalagmitic sides of the Cave, is sufficiently freed 

 from carbonic acid when it reaches the level of the water to de- 

 posit the earth, and thus by continual accretion the edge spreads 

 out into a surface, and the sheet of spar appears to float on the 

 water. Below the surface of the water the aggregation goes on 

 in coralloidal or botryoidal masses, which are coherent, but much 

 less solid than the subaerial deposit. 



The calcareous sheet which is at the surface of the water ap- 

 pears to lose its original pure white colour when the water ceases 

 to flow over it, and it is observed in many other places that the 

 beauty of the surface is soon injured when it is exposed to con- 

 stant or long-continued dryness. 



The surface of stalagmite is generally undulated or excavated 

 in little nests, of which the floor is formed by little bushes of 

 calcareous spar, and the edges are crusted with that substance. 

 This partly arises from the dropping, but is more dependent on 

 the rippling of the thin films of water which readily yield up 

 their earth to prominent points and ridges smooth the larger but 

 augment the smaller inequalities of surface. In the small hollows 

 the crystallization is less rapid and more individualized. The 

 stalactites and pillars show usually a spirality of structure; this 

 is probably the effect of the air-currents. 



