384 THE DEPOSITS. 



But we have still another deposit of clay which rests in a 

 hollow at Mount Row (including Ville-au-Roi, lower part, and 

 a part of King's Road), which I confess to be at a loss to 

 place in time, not having seen any section giving a deposit 

 either above or below. It differs from the glacial clays in 

 colour, being less yellow, and seems to contain ferruginous 

 staining. It has the peculiarity of possessing an unusual 

 modification in that it breaks up, when thrown out of the exca- 

 vation, into pentiform blocks each about two inches in diameter. 

 The horizontal section has the appearance of a honey-comb. 

 This, no doubt, is the result o': pressure acting uniformly on 

 all sides. The deposit is old, for these blocks retain their 

 shape when removed, and although soft in situ they harden in 

 the air without flattening. One piece may be seen in the 

 Museum. The plastic clays I have been describing would not 

 set in the same way. This clay may hi unconnected with the 

 glacial clays, but I must leave this an open question for want 

 of the necessary exposures. 



Note. — While this paper was still in the hands of printer 

 a paleolithic implement of Chellean culture was found in this 

 deposit by Mr. Henry, of Mount Row. 



There is still another clay which is of great use in 

 assisting in fixing the limits of the points of submergence, for 

 it is the product of the decomposition of close-grained diorite 

 rocks, under water. The process of decomposition may be 

 seen in our bays, where the diorite veins start as hard rock at 

 the top of the bay and softens as it reaches the half tide level, 

 and at low water may be taken up as tenaceous blue clay. I 

 have found this at practically all levels, not always easily 

 found, for the external surfaces have become yellow wheie 

 freely exposed, owing to the oxidation of the iron. This 

 deposit is equivalent to sea-washed rock outcrops in tracing 

 sea levels. This kind of clay is rarely distributed and may be 

 taken as being in the position of the veins from which it was 

 formed. When distributed it comes under the oxidising 

 action of the air and soon becomes yellow, therefore indis- 

 tinguishable from other clays. 



The two deposits of glacial clay are to be found in the 

 " Head " which is further built up by them. In places they 

 are distinct and fairly unmixed with redistributed material, 

 but on steep cliffs the loose material has fallen on the deposits 

 when soft and partly suspended by the water over it, with the 

 result that on the cliffs there are more angular stones in the 

 clay part of the " Head " than on the inland plateau. 



