1916.] THE PLEISTOCENE PERIOD. 341 



5th. — The present sea deepened the bottom of the cave 

 three or four feet and left the ledge of 25-foot beach with its 

 rubble standing on a portion of the old platform with its 

 head of rubble still in position and the pebbles of a different 

 beach cemented into its roof. The beach of which the roof 

 shingle is composed must have had an elevation of about 

 50 feet. 



The caves in Jersey seem also to have deposits of two 

 levels, not in the same caves, but at elevations agreeing with 

 the raised beaches of 25 feet and 60 feet. 



The caves which contain deposits must have been formed 

 before the time of the formation of the deposits. 



Although this fact is self-evident, all the writers call 

 attention to it, for fear, probably, that it may be overlooked. 

 Dr. R. R. Marett (Pleistocene Man in Jersey, Archaeologia, 

 vol. lxii, p. 476) calls attention to it in the following words: 

 " The one absolute fact on which it is possible to build is that 

 the two Cottes must have been hollowed out before they were 

 inhabited. It is hardly less certain that they were sea caves, 

 a raised beach forming the bottom layer of the two Cottes." 



Thus the caves are shown to have been formed before 

 the various beaches with which they are associated. It is 

 also evident that the lower caves have been under the action 

 of the sea four times, viz., 1st, the one which opened them ; 

 2nd, the one which deposited the beach stones within them ; 

 3rd, the level which filled them from above (this did not 

 occur in all), and 4th, the present sea-level as far as the lowest 

 caves are concerned. 



The upper caves at levels of 70 feet, and above, can only 

 be said to represent one sea level each. 



These recurring elevations of the changing sea-levels are 

 most interesting and "give one to think." As I see that 

 there may be some help to be gained from the idea I shall call 

 attention to the fact that geologists have found reason for 

 believing that the Channel area has been several times dry 

 land. 



Jukes-Browne in his " Building of the British Isles " and 

 Geikie in his " Great Ice Age " both give instances — but of 

 later periods than the one we are now discussing — of a dry 

 channel. 



In Tertiary times a sinking must have happened, as shown 

 by the Isle of Wight and Bournemouth Beds. Strange to say 

 the latter, between Bournemouth and Christchurch, have well 

 marked deposits of rolled stones, just at the two levels now 

 under discussion, 



