HOW STALACTITES AEE FORMED. 209 



as they have done here, though rarely in equal profusion and attractive- 

 ness. Their formation is simple. Whenever, through some of the mi- 

 nute crevices in the limestone roof or wall, a drop of water trickles, it 

 is sure to be saturated with carbonic acid, and to bear along with it a 

 solution of lime and magnesia. When emerging from its rocky chan- 

 nel it meets with a current of air, it will evaporate and leave behind it 

 minute crystals of carbonate of lime, deposited in the form of a ring, 

 because, as the drop evaporated, the solid matter became more concen- 

 trated around its edges than in the pendent centre. " This ring now 

 becomes the support of the drop, and the process continues until a tube 

 of the diameter of the drop, and from one to thirty-six inches in length, 

 is formed. At this stage of its growth it begins to fill up, and the water 

 now trickling exteriorly deposits its solid matter and enlarges it." This 

 process forms a hanging appendage of stone exactly as icicles grow — 

 large at the top, because the larger part of the lime is deposited before 

 the drop reaches the tip, which nevertheless prolongs itself downward 

 with never-ceasing endeavor to touch bottom. 



But, in the majority of cases, more water flows down a stalactite than 

 can be evaporated, and drops to the floor, depositing, particle by parti- 

 cle, its solid matter in the same spot, directly underneath the tip of the 

 stalactite, until a column corresponding fairly to the size of the stalac- 

 tite is built up ; this is a stalagmite.. In time the upward reach of the 

 one and the downward stretching of the other may join them into a 

 single column, thick or slender, reaching from floor to ceiling. There 

 are many such pillars, seeming to support the roof, in this cave — hun- 

 dreds of them, from the size of a fishing-rod (aud wonderfully resem- 

 bling a bamboo stick, with every node perfect) to that great column in 

 the centre of Giant's Hallj which is fifteen or twenty feet in circumfer- 

 ence and is ribbed like an ancient oak or redwood ; pillars representing 

 all sorts of architectural style in base and capital, for the sculpture-like 

 growth and commingling of these stalactites and crystallizations lend 

 themselves easily to every odd design and fantastic embellishment, which 

 yet never seem inharmonious. 



Though the simple stalactite will be circular and gradually decreas- 

 ing in size, conically, from its attachment to its acuminate point, yet in- 

 numerable variations may occur, as the dripping or streaming water that 

 feeds it is diverted from its direct and moderate flowing. Where it 

 runs slowest, but copiously, or at least continuously, there most lime will 

 be deposited, and the stony image will be built up to the prejudice of a 

 less favored part. Thus it happeris that stalactites often become expand- 



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