CLOSE OP POST-PLIOCENE ADVENT OF MAN. 309 



taries, disappeared under the sea; and some tribs, 

 driven from the lower lands, took refuge in this cave, 

 now again near the encroaching waves, and left there 

 the remains of their last repasts, ere they were driver 

 farther inland or engulfed in the waters. For a time 

 the cavern may have been wholly submerged, and the 

 charcoal of the extinguished fires became covered with 

 its thin coating of clay. But ere long it re-emerged to 

 form part of an island, long barren and desolate ; and 

 the valleys having been cut deeper by the receding 

 waters, it no longer received muddy deposits, and 

 the crust formed by drippings from its roof contained 

 only bones and pebbles washed by rains or occasional 

 land floods from its own clay deposits. Finally, the 

 modern forests overspread the land, and were tenanted 

 by the modern animals. Man returned to use the 

 cavern again as a place of refuge or habitation, and to 

 leave there the relics contained in the black earth. 

 This seems at present the only intelligible history of 

 this curious cave and others resembling it ; though, 

 when we consider the imperfection of the results 

 obtained even by a large amount of labour, and the 

 difficult and confused character of the deposits ia this 

 and similar caves, too much value should not be 

 attached to such histories, which may at any time be 

 contradicted or modified by new facts or different 

 explanations of those already known. The time in- 

 volved depends very much, as already stated, on the 

 question whether we regard the Post-glacial sub- 

 sidence and re-elevation as somewhat sudden, or as 



