THE AVON AND ITS GRAVELS 
231 
directly from some of the Bolderberg or Diestian beds of 
Belgium. 
3. The subangular fragments of flint — some retaining 
their natural colours and others more worn and stained 
brown — are derived, the former directly from the Chalk, 
the latter from an older drift, possibly of the Pliocene age. 
The suggestion of Professor Prestwich that the Kings- 
down gravel may be part of the Wes tie ton Shingle im- 
plies : — 
(a) That this region was submerged until the period 
immediately preceding the glacial epoch ; 
ip) That the enormous amount of denudation which ‘has 
taken place in our district is of glacial and post-glacial age ; 
(c) That of the deposits which must have been formed 
during the submergence all have been removed, leaving 
barely a trace of their existence. 
These conclusions had of course been considered by 
Professor Prestwich ; yet on the evidence only of the 
similarity of the deposit to the Wes tie ton Shingle, he is 
reluctant to exclude this western district from the sub- 
merged area. He writes,^ “ Of the escarpment of the 
Oolites one can speak with less certainty, though if we 
admit the Kingsdown drift to be of the Westleton age, 
it favours the conclusion that the escarpment of the 
Oolites dates no further back than the commencement 
of the Quarternary or Pleistocene period. The fact 
likewise that the two escarpments (i.e. of the Avon 
oolites and of the Chalk) run in parallel lines seems to be in 
favour of a common denuding cause in the same direction. 
The time, geologically measured, is, however, so limited 
and the extent of the denudation so vast, that it is not 
easy to realize that these limits can suffice. Nevertheless, 
I do not see how the conclusions we have arrived at on this 
subject can well be avoided.” 
1 Quart. Journ. Geol. Soc., xlvi., p. 151 (1890). 
