MAMMOTH CAVE (ante), though the largest, is but one of a very large series of caves, lying beneath extensive districts of both Tennessee and Kentucky. It was dis covered 1809, and has always been private property. The principal stream, Echo river, is nearly three-quarters of a mile in length and has underground communication with Green river; the Styx is about 450 ft. long and is remarkable for a natural bridge of great beauty. Passan.es and avenues connect chambers or halls, placed at different levels; thus showing the slow progress of the stream in its course through the earth: Accurate measurement of the passages has never been permitted. The extreme length is said to be from 8 to 10 in., while the total length of passages cannot be less than 150 miles. Several of the largest chambers, called domes, extend through the entire height of the levels. Of these the most notable are the Stella, Mammoth, and Gorin's domes, each about 250 ft. high, and Lucy's donne, over 300 ft. high and 00 ft. in diameter. Cleveland avenue extends for more than 2 m. and presents a most wonderful variety of crystals and incrustations, " some massive and splendid; others delicate as the lily." All of the halls offer to view numbers of stalagmites and stalactites, which in their varied and fantastic shapes—sometimes exhibiting weird or grotesque resemblance to riatural or architectural objects--form, in conjunction with the streams and fountains, the picturesque scenery of the cavern. Startling effects are produced by the use of lights and -fireworks, the Star chamber showing on its ceiling myriads of the glistening points from which it takes its name.
Geologists assign a. million years as the approximate term for the production of this series of caves. There is at present no growth, but, on the contrary, a slow but continual decrease iu size by the natural causes of decay and accretion. The process of formation. seems to have been as follows: In their course through the soil the streams absorb'a large amount of carbonic acid gas; this possesses the chemical power of taking up considerable quantities of carbonate of lime, thus by varied action forming large cavities, and deposit ing the carbonate, in part, on ceiling or floor or in the stalagmite and stalactite forms, and, in part, carrying it off into the river. In this way the caverns are in succession produced snd closed up.
The variations in both the insect and fish life of the 'Mammoth cave from the ordinary type are scientifically of the highest interest as bearing upon and, it is claimed, favoring the doctrines of evolution and natural selection. That variation has taken place to accommodate animal life to exigencies of environment caunot be doubted, when we -examine the blind and the totally eyeless species of fish and crawfish here found. It is not improbable that, if more thoroughly explored, fossil testimony of great value might he discovered