132 SWAMP DEPOSITS 



beautiful shapes of every description, fringes of crystal spar, and 

 curtain-like draperies hang from the roof and cover the walls of 

 the chambers, while grotesque shapes rise from the floor, which is 

 itself often a solid mass of the same deposit, and the pillars, once 

 formed, are ornamented with every variety of fringe and sculpture. 

 The constancy of the paths by which the water descends through 

 the roof of the cavern, insures that the process shall continue 

 uninterruptedly for very long periods of time. The Luray Caverns 

 of Virginia are famous for the bizarre beauty of their formations, 

 but limestone caves everywhere have more or less of the same 

 deposit to show. 



This process may be readily observed in any masonry arch, 

 through which rain-water percolates, as a bridge, for example. 

 The lime of the mortar is converted, in course of time, by contact 

 with moist air, into CaC0 3 , and this again is partially dissolved by 

 the rain. When the rain-water trickles through the arch, it leaves 

 icicle-like deposits, or thin sheets of calcareous matter, fringing 

 the under side. 



In a cave, it frequently happens that angular fragments fall 

 from the roof and are cemented into a breccia by deposits of 

 stalagmite. In caves connected with the surface by openings, 

 sand and gravel, or fine soil and loam, are washed in by streams, 

 or by the rain, and form the characteristic deposit known as cave 

 earth. In ancient caverns, no longer subject to this wash, the 

 whole deposit of earth may be sealed in by a covering of stalag- 

 mite. Cave earth has, in many instances, yielded great quantities 

 of bones, which were washed in with the earth, or dragged in by 

 the carnivorous animals which inhabited the cavern. The Port 

 Kennedy cave in Pennsylvania is almost filled up by the bones of 

 extinct animals which were washed into it, and many such cases 

 are known, especially in Europe. 



II. Palustrine or Swamp Deposits 



The most important of the swamp and bog deposits are the 

 vegetable accumulations, for the preservation of which a certain 



