BONE-CAVES IN NORTH WALES. 15 



by Other beasts of prey as dens, into which portions of carcasses 

 of various animals were conveyed in Pleistocene times. The 

 animals were those usually found in the bone-caverns of this age, 

 in this country, and so far no new species have been added to those 

 already known to be common to these caverns. The very great 

 abundance of some animals, such as the Rhinoceros, Horse, and 

 Reindeer, and the frequent presence of bones belonging to young 

 animals prove that the plain of the Vale of Clwyd, with that ex- 

 tending northward under the Irish Sea, must have formed a favourite 

 feeding-ground even at that time. The evidence furnished by the 

 flint implements and broken bones that man was contemporary with 

 these animals, is useful in confirmation of discoveries in other 

 caverns. The facts, perhaps, of greatest importance made out 

 during these researches are those which bear on some questions of 

 physical geology in regard to this area, which have hitherto been 

 shrouded more or less in doubt. The views on the physical condi- 

 tions in Pleistocene times of the areas in jN'orth Wales in which 

 these and the other bone-caverns occur, so ably put forward by Sir 

 A. Eamsay, are, in my opinion, strongly supported by the results 

 obtained in our explorations, and it appears to me very difficult to 

 account for the facts observed in any other way than by accepting 

 his general conclusions. The ravine in which the caverns occur 

 must have been, scooped out previous to the deposition in it of the 

 glacial sands and Boulder-clays. These sands and clays, there 

 seems good evidence to show, must have filled up the ravine to a 

 height above the entrances to the caverns, and such deposits are 

 now found in some parts to completely fill up the caverns. How, 

 then, did these sands and clays get into the caverns ? Were they 

 forced in through the entrances by marine action, or by a glacier 

 filling the valley ? Or were they conveyed in subsequently to the 

 deposition of the Boulder- clay in the valley and surrounding area ? 

 The position of the caverns, as shown in the sketch (fig. 1), in an 

 escarpment of limestone at the end of a ridge of these rocks, 

 with a sharp fall on either side, prohibits the idea that the material 

 could have been washed in from the higher ground, if the latter had 

 anything like its present configuration. Moreover there is scarcely 

 any deposit now visible upon the limestone ridge, and there is no cer- 

 tainty that any great thickness of such a clay as that now found in 

 the caverns ever was deposited there. Of course I do not maintain 

 that this was not the case, but there is no evidence at present 

 to prove that it was so. The general position of the bones and the 

 condition of the deposits in some of the tunnels seem to me to 

 indicate clearly that the force which broke up the stalagmite floor, 

 in some places from 10 to 12 inches in thickness, and stalactites from 

 6 to 8 inches across — thrust many of the large and heavy bones into 

 fissures high up in the cavern and placed them at all angles in the 

 deposits — must have acted from the entrance inwards ; and the only 

 forces which seem to meet these conditions are marine action, or 

 those accompanying the passage of a glacier down the ravine. ^Jy 

 own opinion, after considering all tlic evidence obtained, is rather 

 in favour of the former than of the latter cause. The followinsr 



