370 THE DEPOSITS. 



Channel coasts, and as the sea-level reached the old 25 feet 

 beach, the ice began to eat off the beach, and in this way a 

 large part of the outer portions of that beach were eroded 

 off from the positions on which it had managed to retain 

 itself. 



The islands sank further and the point of stability at 25 

 feet was passed and the next, that of 50 feet, held the sea for a 

 short time, and the ice mounted the cliff* and grounded on the 

 shores, tearing out from the one and twisting off from the 

 other the frost detached rock blocks and thus laying down 

 the first part of the " Head." 



These angular blocks fell on the remainder of the 25 feet 

 beach, and, as they were soon covered by the future deposits, 

 they still rest there. 



The sinking continued. and one after the other the islands 

 were divided from each other. I think there is reason to 

 suppose that Jethou was much longer under the influence of 

 the floating ice than Herm for the enormous blocks (see 

 Transactions, Vol. I., Jethou), appear to me to have been 

 moved in larger numbers than those of Herm. To understand 

 this we have only to look at the map of the united islands 

 to see that the ice would be able to attack Jethou 

 from the South side before it would reach Herm where the 

 water was less deep. 



The submergence I am now describing I term " the 

 Pre-Mousterian " so as to distinguish it from the first which I 

 described as - Pre-Glacial." 



By its consequences on our island we recognise this 

 glaciation. 



It will naturally be asked where the floating ice came 

 from ? Of course, the island does not afford evidence on this 

 point, so we have to accept the statement of the Glacialists 

 who tell us that the bergs calved off the land in the Irish sea 

 and floated down the Atlantic as far as mid-Atlantic islands. 



Not all of them though, for a large number of them, 

 under tidal and gulf stream pressure, got into the Channel and 

 there became jammed. 



Assuming that this part of the Channel was covered with 

 ice which would consist of small bergs and pack-ice under 

 pressure, it would follow the course of the circulating water 

 and have a general movement around the French coasts, 

 forcing its way through the passages between the islands. 

 Those passages would be more constricted than they are at 

 present owing to the Casquet, Schole and other banks being 

 then above water ; indeed, we may take it that it was at this 



