ARTICLES 91 



ment is this : over the shelf of the beach lie four deposits, 

 indicating alternations of cold and warm climates. Beginning 

 at the bottom they are (1) the beach itself (arctic) ; (2) 

 cemented sand (warm) ; (3) " Head " or Coombe Rock (cold) ; 

 (4) Boulder Clay (arctic). Various observers have associated 

 the Chellean industry with a warm period occurring between 

 the last glacial episode (Giinzian, in Penck's scheme) and the 

 last but one (Rissian) ; and since the fauna of the cemented 

 sands agrees on the whole with that of the Chellean deposits 

 of the Thames, and the Coombe Rock is known to be post- 

 Chellean, it is assumed that the sands in question are of early 

 palaeolithic age. Mr. Dewey frankly admits that no imple- 

 ments have yet been found in the cemented sands ; but he 

 does not meet the other obvious objection that no contemporary 

 Chellean implements have yet been proved to occur in river- 

 drift at such low levels in this country. This is no place to 

 discuss the large and difficult question of how far Penck's four 

 glacial episodes are traceable in England, but a word must 

 be said as to the relation of the Chellean deposits to the Chalky 

 Boulder Clay. Mr. Dewey, in common with most English 

 geologists, believes that the latter is the older ; but although 

 this conclusion is very possibly sound, the premises on which 

 it rests have recently been challenged by Mr. Kennard, 1 and 

 it must be admitted that they are of such an unsatisfactory 

 character as to make it surprising that they have been so long 

 and so widely accepted. 



Reliance is usually placed on four localities : (1) Biddenham, 

 (2) Hoxne, (3) Warren Hill, and (4) Hornchurch. In the first 

 case the valley of the river Ouse is supposed to have been cut 

 through Boulder Clay before the implementiferous gravels were 

 deposited in it ; but as Mr. Kennard points out, the evidence 

 produced by Mr. Boswell and others that our main valleys 

 are older than the Chalky Boulder Clay seriously weakens the 

 argument : and the same may be said of Mr. Dewey's own 

 conclusion that the raised beaches of Brighton, etc., only a 

 few feet above O.D., are pre-Chellean. The low level of the 

 gravels, too (about 40 ft. above the river), makes it doubtful 

 whether they can be correlated with those of the 100 ft. terrace 

 of the Thames. 



At Hoxne the implements are mainly, if not wholly, of 



1 Proc. Prekisl. Soc. E. Anglia, vol. ii. pt. ii. p. 249. 



