102 GLEANINGS FROM NATURE. 



eroded. The larger caves possess great vaulted rooms, 

 deep pits, high water-falls and streams of water ; some 

 of the streams being large enough to allow the ready 

 passage of a good-sized boat. 



From the above it will be seen that sink-holes and 

 caves are closely related, the latter, in fact, being 

 largely dependent upon the funnel shape of the for- 

 mer to collect the surface waters and direct the flow 

 thereof. A number of sink-holes often connect by 

 narrow and tortuous channels with the same under- 

 ground passage, the latter increasing in size with the 

 addition of each new branch, until finally it attains 

 majestic dimensions. 



The rooms and passages of limestone caverns are 

 often, after their formation, partially filled by those 

 handsome forms of crystalline limestone, called sta- 

 lactites and stalagmites. These are seldom, if ever, 

 formed in great numbers, except where the passages 

 or rooms are close to the surface. The water, charged 

 with carbonic acid, filters slowly through the soil, 

 and, entering the narrow crevices and joints between 

 the layers of stone, seeps downward until it pierces 

 the roof of an under-ground cavity. Here the slowly 



dripping water comes in contact with 

 Formation of ^ air f th caye The R id . 

 Stalactites and 

 Stalagmites, evaporated and the solid particles or 



carbonate of lime, dissolved from the 

 rocks with which it had come in contact, are left be- 

 hind. Each successive drop thus deposits or leaves a 

 solid particle, until finally a pendent cylindrical mass, 

 called a stalactite, and resembling in general form an 

 icicle, remains suspended from the roof. 



