232 RAISED BEACHES, CLIFF AND RUBBLE HEADS. 



existing in the immediate neighbourhood. Exceptions to this 

 rule exist, but with our present knowledge we are bound to 

 reason on the fact as stated. This portion of the cliff-head 

 will vary from one to six or seven feet in thickness. The next 

 layer, though mixed up with the first in a sense, is neverthe- 

 less a distinct formation. It is a sandy clay. This also varies 

 in its nature, being more sandy in some places than in others, 

 where a small rubble and clay mixture seems to rule. The 

 probability is that a stony mass was first deposited, and the 

 sandy clay, which came next in order, permeated into the 

 interstices of the fallen stone, and thus produced the apparent 

 mixture. This formation rarely exceeds fifteen feet, and in 

 some cases does not exist. This is followed by a rubble-head 

 more or less distinct from the lower portions, and in places 

 possessing the appearances of bedding, very indistinct, but 

 traceable wherever a long section is exposed to view. 



This band is never very decided, and no general depth 

 can be given to it, but at Divette Mr. Cooper fixed its depth at 

 5 feet. I think it would be fair to average it at that figure, 

 but I really believe that I have found it as deep as 8 feet in 

 one or two places inland, to be alluded to directly. 



We next come to a distinct and very well marked layer 

 of clay. This is very plainly marked everywhere in the head. 

 It is yellow in colour, of good plastic consistency and very 

 impermeable to water. It is to this clay layer that the con- 

 cretions and breccia existing at St. Martin's Point and studied 

 by the geological section, only yesterday, is due. At Divette 

 this layer is four feet in depth. At St. Martin's Point it is in 

 places quite eight feet thick. I am inclined to give it an 

 average not much below eight feet, but I am not sure that 

 I am right in this. Over this clay is usually a clayey sand 

 and earthy clay, true earth and mould. These upper layers 

 are very modern, and will not be of much importance in 

 forming conclusions. 



THE RUBBLE-HEAD 



Is a formation met with inland. I have found it generally 

 present on the sides of hills and hougues, very visible in road- 

 side cuttings, field hedges, where the field has been lowered, 

 and on the sides of quarries. It usually rests on the rock of 

 the district, and roughly follows the order of deposition found 

 in the cliff-heads, commencing with the upper bands of rubble, 

 upwards. 



The true cliff-head is found wherever a cliff exists in the 

 island, but where the slope is gentle > and inland it is more 



