40 Reports and Proceedings — 



portions of carcasses of various animals had been conveyed in Pleis- 

 tocene times. The very great abundance of some animals, such as 

 the rhinoceros, horse and reindeer, and the frequent presence of 

 bones belonging to young animals, proved that the plain of the Vale 

 of Clwyd, with that extending northward under the Irish Sea, must 

 have formed a favourite feeding-ground even at that time. The 

 flint implements and worked bones showed also that man was 

 contemporary with these animals. The facts perhaps, however, of 

 greatest importance, made out during these researches, are those 

 which bear on some questions of physical geology in regard to this 

 area, which hitherto have been shrouded more or less in doubt. The 

 views on the physical conditions in Pleistocene times of the areas in 

 North Wales in which these and the other bone-caverns occur, so 

 ably put forward by Sir A. C. Eamsay, appeared to the author to be 

 strongly supported by the results obtained in these explorations. 

 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. 

 This sand and clay, there seems good evidence to show, must have 

 filled up the ravine to a height above the entrances to the caverns, 

 and such sands and clays are now found at some points 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 

 subsequent to the deposition of the Boulder-clay in the valley and 

 surrounding area ? The position of the caverns 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, as has been suggested by some 

 in the case of other caverns, if it had anything like its present con- 

 figuration. Moreover, there is scarcely any deposit now visible upon 

 the limestone ridge, and there is no certainty that there ever was 

 deposited there any great thickness of such a clay as that now found 

 in the caverns. The general position also of the bones in some of 

 the tunnels seems to indicate clearly that the force which broke up 

 the stalagmite floor, in some places 10-12 inches thick, and stalac- 

 tites 6 to 8 inches across, which thrust many of the large and heavy 

 bones into fissures high up in the caverns and placed them at all 

 angles in the deposit, and must have acted from the entrance inwards, 

 and the only force which seems to meets these conditions is marine 

 action. The following seem to the author to be the changes indicated 

 by the deposits. The lowest in the caverns, consisting almost entirely 

 of local materials, must have been introduced by a river which flowed 

 in the valley at a very much higher level than does the little stream 

 at present. Gradually, as the valley was being excavated, and the 

 caverns were above the reach of floods, hyaenas and other beasts of 

 prey occupied them, and conveyed the remains of other animals into 

 them. Man also must have been present at some part of this period. 

 Gradually the land became depressed, the animals disappeared, sta- 

 lagmite was formed, and the sea at last entered the caverns, filling 

 them up with sand and pebbles, and burying also the remains not 



