Ch. XXI.J 
ALLUVIUM OF WEALD VALLEY. 
297 
of the chalk and its flints in the deep valleys of the Forest 
ridge. Indeed, if we adopted the diluvial hypothesis of Dr. 
Buckland, we should expect to find vast heaps of broken flints 
drifted more frequently into the valleys of the Gault and Weald 
clay, instead of being so frequently confined to the summit 
of the chalk downs. On the other hand, it is quite conceivable 
that the slow agency of oceanic currents may have cleared 
away, in the course of ages, the matter which fell into the sea 
from wasting cliffs. The reader will recollect our account of 
the manner in which the sea has advanced, within the last cen- 
tury, upon the Norfolk coast at Sherringham *. 
No. 72. 
Section of cliffs west of Sherringham. 
a, Crag. b, Ferruginous flint breccia on the surface of the chalk. 
c, Chalk with flints. 
The beach, at the foot of the cliff, is composed of bare chalk 
with flints, as is the bed of the sea near the shore. No one 
would suspect, from the appearance of the beach at low water, 
that a few years ago beds of solid chalk, together with sand 
and loam of the superincumbent crag, formed land on the very 
spot where the waves are now rolling ; still less that these same 
formations extended, within the last 50 years, to a considerable 
distance from the present shore, over a space where the sea has 
now excavated a channel 20 feet deep. 
As in this recent instance the ocean has cleared away part of 
the chalk, and its capping of crag, so the tertiary sea may have 
swept away not only the chalk, but the layer of broken flints 
on its surface, which was probably a marine alluvium of the 
* Vol. i. p. 268, and Second Edition, p. 307. 
