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CHAPTER XX. 



ON SUBTERRANEAN RIVERS AND CURRENTS, AND ON CAVERNS. 



Occurrence of Subterranean Currents and Rivers in various Parts of the World. — 

 The Principal Agents in the Formation of Caverns. — Remarkable Cavern and 

 Cascade in the Speedwell Mine, Derbyshire. — Subterranean Currents and Cav- 

 erns generally in Calcareous Mountains. — The reason explained. — Subterrane- 

 an Currents connected with the Surface Water, deposit Animal and Vegetable 

 Remains between ancient Strata, proved by Facts. — Caverns with bones of ex- 

 tinct Species of Animals in Germany and France, intermixed with Human 

 Bones, and Implements of Industry. — Bones introduced into Caverns by Subter- 

 ranean Currents and other causes, and at different Epochs. — Cavern at Kirk- 

 dale, in Yorkshire. — Bones found in the Clefts and Fissures of Rocks forming 

 Osseous Breccia in various Parts of Europe, and in New Holland. — Epochs of 

 their Deposition supposed to be different in distant Parts of the Globe. 



Beside the fissures and spaces filled with metallic matter, that oc- 

 cur in the older rocks, as described in the preceding chapter, there 

 are empty spaces or caverns, that sometimes extend far into the in- 

 terior of mountains, and sometimes descend to considerable depths. 

 Almost all large caverns occur in limestone rocks, chiefly of the 

 transition and the secondary class. Caverns, in some instances, may 

 have been formed by the upheaving or subsiding of rocks; but they 

 have, most frequently, been excavated by subterranean currents of 

 water, which have enlarged original fissures, or carried away the beds 

 of soft clay or loose sand that were interposed between hard strata. 

 Many large caverns have streams of water constantly running through 

 them ; and, after heavy rains, they are often gorged with water, 

 which issues with violence from their mouths. This is the case with 

 the great Peak Cavern, near Castleton, in Derbyshire. 



The action of subterranean currents of water, has scarcely been 

 attended to by geologists ; but were it betier understood, it might 

 probably afford a satisfactory explanation of several facts in geology 

 that have been regarded as anomalous, particularly that of the oc- 

 currence of bones in caverns which have no opening to the surface. 

 In the third edition of this work, I stated some instances of these 

 currents in mountain limestone. 



The mountain or transition limestone of Craven, in Yorkshire, 

 forms, in many parts, a nearly flat elevated surface of table land, 

 covered with vegetation, but intersected by numerous fissures or 

 chasms of vast length and depth, varying from a few inches to a foot 

 or more in width. Many of these fissures widen as they descend ; 

 and at the bottom, streams of water may be, frequently, heard run- 

 ning. During snow, it is not uncommon for sheep to be lost in these 

 chasms, and the whole surface is extremely dangerous, to traverse 

 in the dark. Limestone plains, intersected by such fissures, may be 

 regarded as natural traps for herbivorous animals, into which, when 



