Caves, Mendip Hills. 473 



from the mainland, for the waste of sea cliffs as hard 

 as the Carboniferous Limestone is so slow, that the life- 

 time of generations of men sees but little change in 

 their outlines, and rude camps and earthworks of un- 

 known age even now stand on many a hard rocky pro- 

 montory, almost as fresh as the day when they were 

 first constructed. These were my first reflections when I 

 saw the traces of the old mammalian inhabitants of 

 what now is Caldy, and the same train of thought is 

 entertained by Professor Dawkins in his book on ' Cave 

 Hunting.' They are sufficiently obvious to all who are 

 not imbued with a sense of unprovable and needless 

 cataclysmic forces. 



On the eastern side of the upper part of Bristol 

 Channel, the Mendip Hills, and other large bosses of 

 Carboniferous Limestone, are seamed by numerous 

 caverns charged with bones. Taken all in all, the 

 assemblage is much the same as that found in the caves 

 already mentioned, and like some of these, the bones, 

 as remarked by Dr. Buckland, were carried into under- 

 ground water-channels by streams falling into swallow- 

 holes. This involves a very considerable change in the 

 physical geography of the region since these streams 

 ran. Unless the Carboniferous Limestone be more or 

 less coated with impermeable strata, such as Red Marl, 

 Lias clay, or Boulder-clay, the rain immediately sinks 

 through innumerable joints open to the surface, and 

 thus it happens that rivers, or even unimportant brooks, 

 are rare in tracts formed exclusively of masses of lime- 

 stone. From the evidence of outlying remnants, it 

 seems probable that the Mendip Hills were once ex- 

 tensively covered by a thin casing of Lias clay, over 

 which streams ran in the Pleistocene epoch, and carried 

 the bones of dead animals into swallow-holes, just as at 



