332 MOULIN HUET AND ICART CAVES. 



through a passage 4 feet wide and formed of the two sides of 

 the gully. Immediately after entering, the eye is struck by 

 the presence of a ledge of rock forming a raised platform, on 

 the top of which is a mass of conglomerate which seems to be 

 continued up the back of the cave and is spread over the roof, 

 being suspended by its cemented condition. The top of the 

 roof is some 40 feet above the mean sea level, and this great 

 height made it difficult for the members of the Society present 

 at the excursion when the Icart cave was examined to believe 

 that these caves could have been filled from the present beach, 

 and yet that was the only explanation then possible. 



The facts ascertained which have led to a better theory 

 are as follows : First — Mr. J. J. Carey and I made careful 

 measurements of the various deposits and found that the 

 conglomerate was at a mean height of 25 feet above mean sea 

 level. This conglomerate formed a flat bed quite distinct 

 from the pebbles which rested upon it and filled up the 

 cave, but at that time we did not find the explanation. I 

 gave a full account of the results of our examination in my 

 presidential address in the year 1892. The matter was left 

 undetermined and the puzzle of how the pebbles got in the 

 caves and filled them up to the very top remained unsolved. 



The history of the caves has now been worked out and is 

 as follows. We must divide the process into three stages : 



1. — Quite a long time ago, long before the glacial epoch, 

 the shape of the island was cut out by an eroding sea. It 

 may have been during Eocene times or more probably during 

 late Pliocene times, for the Bournemouth Beds show that then 

 the sea level was much the same as now. Indeed, the carving 

 Out of our coasts may have been the result of several returns 

 to the same levels. One thing is certain, namely, that the 

 depression of the island which existed when the sea laid down 

 the 25' beach and cut the rock platforms associated with that 

 level found the island of the same shape as at present, if we 

 allow for the separation of the outlying rocks and terminal 

 promontories, otherwise the 25' beach would not have followed 

 the coast line as it does. 



That being the case we must believe that the rocks, 

 which by their decomposition gave rise to the caves, were 

 already brought under the influence of the sea. The sides of 

 the caves, being hard rock, resisted erosion, but the then 

 existing cliff" was washed from the base and an opening was 

 made at the level of the time into the softer rock between the 

 two hard sides. This opening was of small size, a mere 

 beginning in fact. - 



