116 PEOr. T. M'KEXNT HUGHES 



Magazine' in N"ovember *, especially noticing that the blocking of the 

 upper opening seemed to have taken place gradually, and that while 

 it was going on drift-material was washed into the cave, and various 

 objects got into the crevices of the broken limestone — my point 

 always being that the upper opening was not stopped by undisturbed 

 drift, but by moved and slipped portions of the drift and of the over- 

 lying head or rainwash; and that even if it had been blocked by 

 undisturbed drift, such as lay on the hill-side near by, that would 

 not prove the contents to be preglacial, because that marine drift 

 was not laid down tiU after glacial conditions had entirely ceased to 

 prevail in that district. 



I explained my views on the subject in a lecture delivered at 

 Chester in October 1886 f, in which I pointed out that the cha- 

 racter of the drift was not such as to allow us to refer it to an 

 ordinary beach-deposit, but it must have crept down the hill-side 

 either subaerially or into deep water, where there would not be the 

 same sorting of the material as is usual on such a coast; that the 

 drift which finally closed the cave was in its upper part superficial 

 talus, and below that moved marine drift, but that there was a com- 

 munication with the cave from the surface by swallow-holes down 

 to quite late times. 



In November of the same year I read a paper J before this 

 Society, in which I discussed more fully the characters of the various 

 drifts in the district, giving my reasons for assigning to the deposits 

 outside the Cae Gwyn Cave a place among newer series which I 

 considered not to have been laid down until after glacial conditions 

 had passed away from that area. I gave fuU lists of shells from the 

 marine drifts of that and adjoining areas, but at that time the shell- 

 bearing bed at Cae Gwyn had not been touched. I again stated my 

 reasons for believing that the drift-deposits outside Cae Gwyn Cave 

 were not a true beach, but the result of the working down the slope 

 cf debris from the drift, first into deep water, and subsequently sub- 

 aerially ; and that " the drift which finally closed the mouth of the 

 cave " (p. 110) was not even as old as the marine drift, but that 

 some of the material was a mere superficial talus, that some of it 

 was the moved drift (p. 104) which had sunk into an irregular 

 swallow-hole, and that all the drift which overlapped the bones had 

 settled down on them in consequence of this swallow-hole action 

 long subsequent to the deposition of that drift (p. 109). 



In the 'Geological Magazine' of December 1886, Dr. Hicks § 

 reprinted the Eeport which he had drawn up for the Meeting of the 

 British Association at Birmingham, with a long footnote commenting 

 upon the observations I had made on the subject. 



He states that the accumulation against the upper side of the old 



* " On the FfynBon Beuno Caves," Geol. Mag. Nov. 1886, dee. 3. vol iii 

 p. 489. 



t " Caves and Cave Deposits," ' Chester Chronicle,' Nov. 6, 1886. 



+ " On the Drifts of the Vale of Clwyd and their Relations to the Caves and 

 Cave Deposits," Quart. Journ. Geol. Soc. vol. xliii. 1887, p. 73. 



§ " On the Ffynnon Eeuno and Cae Gwyn Caves," Geol. Mag. Dec. 1886, 

 dec. 3, vol. iii. p. 666. 



