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floor, and pieces of the roof becoming detached partially fill 
the unused ways with debris. As this goes on, stalactitic 
and (foreseen t stalagmitic formations accumulate in these 
stormless old river channels. The sign of water action in 
the rocks is wonderfully preserved, and tells its tale of 
stream-wear or drift-wear more faithfully than in valleys 
exposed to rains, vegetation, and changes of temperature. 
The unaccustomed darkness and the strange shadows cast 
by the lamps of visitors give to these accumulations, masses 
of debris, and water-worn roofs and walls, weird shapes 
which are fancifully supposed to resemble familiar objects 
above ground. Their own individualities, so different from 
anything on the surface, give them a far stronger claim on 
the observer s interest. 
Amid slightly undulating woodlands about 325 feet above 
Green River, lies a depression some 80 feet deep, and at one 
place the sandstone bottom of this depression has fallen 
away, exposing an opening into the “Mammoth Cave,” 
whose upper and lower chambers are known to extend for 
200 miles, and to communicate with further unexplored 
channels. 
After a descent from the open air of about 60 feet, the floor 
of the “Water Cave” is reached. This has been dry as long 
as it has been known. Indeed, as it is nearly 200 feet 
above Green River (the drainage level in this district), the 
water must for ages have been able to traverse large lower 
channels. 
The old deposits of mud in these upper caves have been 
so saturated with saltpetre that they have been washed as 
early as the war of 1812. On the theory that this saltpetre 
is derived from bat-guano, acted on by the dry atmosphere 
