368 THE DEPOSITS. 



2nd. — Boulders, that is stones of all sizes which have 

 been rolled and moved from their place of origin. 



3rd. — Rubble of aerial origin. 



4th. — Clays (a) of local origin ; (b) of glacial origin. 



5th. — Deposited sands, wind blown sands and gravels. 



6th. — Beach stones and pebbles, in situ or redistributed. 



In this list it will be perceived that there is no " Head " 

 having the same nature as the Brighton " Elephant Bed," but 

 nevertheless our " Head " covers the same period, for it covers 

 all the Pleistocene Period, but we are not influenced by the 

 more recent " Head " to place the whole formation down to 

 one portion of that period. 



We have, in the islands, no equivalent of that bed in the 

 Raised Beach Period, with which it is associated by Prestwich 

 and others ; on the other hand the discovery of the Elephas 

 Antiquus in Jersey places any possible equivalent, in the 

 islands, much later in time than the Beach Period. 



I have stated the deposits which go to form the " Head " 

 and the fact that it extends all through the period under 

 discussion, and I must now leave it to the future stages to 

 show how each component has been acquired. 



After the deposit of that portion of the " Head " described 

 under " Emergence " the conditions became severely glacial, 

 The ice-cap was permanent and it performed a great work in 

 breaking down the upper levels of the island, but as already 

 stated it does not seem to have directly added to the "Head " 

 nor to have caused any deposit that can be identified ; yet it 

 will be evident that it had an enormous effect in reducing the 

 rock material to a condition favourable to its future deposition 

 on the island surfaces. 



The elevation was high enough to connect the group of 

 the three islands, Guernsey, Herm and Jethou for the 

 North-East end of Herm was not affected by the early 

 advent of floating ice-floes as was the North end of Guernsey. 

 An ice-cap rested on all three islands no doubt, but its effect 

 on each was different. On Jethou we find no decomposed 

 rock and no glacial clay. The one thing means the other for, 

 as I shall show, the glacial clay is the result of the friction of 

 the ice-cap on the easily rotted and decomposed rocks of the 

 southern half of Guernsey. There being no soft rock in 

 Jethou the ice simply rubbed it bare and left it so. 



Not so, however, in Herm. The rocks of the higher 

 portion of Herm are soft enough to have been permeated by 

 water and broken by the subsequent freezing to be worn away, 

 but with a distinct difference from anything we find in 



