340 THE PLEISTOCENE PERIOD. 



No. 3, the Channel and Islands low level beach. 



No. 4, the 50 feet Beaches in Jersey and Guernsey, 

 including the Gower Caves and the Jersey Caves. 



No. 6, Period of occupation of Caves. 



At various elevations, in all the islands, are to he found 

 caves, rock-fissnres and sea-eroded rocks. 



These begin with the sunken and submerged caves of 

 Sark and end w T ith the sea eroded rocks and fissures of our 

 south coast where they exist at an elevation of 270 feet. 

 (Corbiere caves.) 



These alone point to recent changes of level, but such 

 changes are also indicated by extensive rock-platforms and 

 raised beaches, the difficulty being to assign correct relative 

 periods and sequences to all these geological data. 



The caves which exist here have their counterparts on 

 the coasts of the English Channel and in the other islands of 

 our group. 



These caves are usually associated with definite levels of 

 the sea as indicated by former beach deposits or sea eroded 

 margins. 



Thus we have caves in Sark with their bottoms below sea- 

 level and beach deposits on our west coast 12 feet below O.D. 



We also have caves with their bottoms at the same 

 height above the present sea-level as the 25 ft. beach. (Dog's 

 cave at Icart Point and Moulin Huet cave.) 



In the caves we have but little to guide us as to sequence, 

 but I think the evidence of Moulin Huet cave does offer 

 strong evidence that the 50 ft. to 60 ft. beach followed and 

 was in that cave laid on the 25 ft. beach. (See separate 

 paper in this volume at page 331.) 



This association is not admitted for like caves in Jersey. 

 The evidence here is as follows : — 



1st. — A rock crevice was formed and existed as a cave 

 with a low and constricted entrance. 



2nd. — Through the entrance the 25-foot sea, assisted by 

 the pebbles of its beach, worked a flat platform and deposited 

 thereon a 4-foot layer of pebbles. These are now a conglo- 

 merate. 



3rd. — An interval of time followed during which the 

 cave was not under the action of the sea and rubble fell from 

 the decaying roof and partly filled the cave, resting upon the 

 conglomerate. 



4th. — The conglomerate was in its turn covered by a new 

 deposit of beach, apparently through an opening in the roof, 

 and this became, in its turn, cemented into a conglomerate. 



