Florence J. Relf—Some Wealden Sands. 301 
support to the view that the stream bearing their material came from 
a westerly direction. If it did—and this was Jukes-Browne’s view 
—it would, of course, be probable that tributaries joined it on its 
way to the southern sea. A tributary from the north-west coming 
over the Trias rocks of the Midlands may have brought the pebbles 
of liver-coloured quartzite mentioned by Lamplugh? as occurring in 
a boring at Dover, and considered by him to have come from the 
north-east. 
On the whole, this study of the minerals in the Ashdown Sands 
points to the conclusion that the majority of the material was brought 
by a large river from the west or south-west. On the question as to 
whether - the Wealden beds were laid down in a lake’ or as a delta, the 
results of the investigation have been disappointing. Although the 
Wealden river is believed finally to have reached the sea which then 
occupied the Mediterranean area, the only known estuarine deposits 
of that age which are of any considerable importance are those in ° 
the Haute Marne district. If the Wealden river and the Southern 
Sea were connected through this area, the subsequent invasion of the 
Vectian sea north-westward would have been the natural one of 
advance up a river valley. iS 
If the theory that the Wealden river broadened into a lake be 
accepted, an outflowing stream must be supposed to have emerged 
from the south-east end, and this stream to have broadened no 
a delta which was subject to invasion by the sea. If the lake did 
exist, the stream emerging from it must have been fairly free from 
sediment, and the thinning of the Wealden deposits, eastward, bears 
out this view. In this case it is difficult to imagine how all the 
material necessary to the formation of deltaic deposits could have 
been accumulated between the lake and the sea. It is true that the 
Haute-Marne estuarine series is only about 60 feet thick, but it 
extends over a fairly wide area, and represents a greater amount of 
erosion than seems possible between the lake and the delta, unless 
a stream from another direction joined in at this point; and of this 
there is, I believe, no evidence. 
On the éther theory—that our Wealden Series is estuarine—the 
assumption is that the deposits are only part of the wide estuary, of 
whose lower end there are still remains in France. The alternation 
of clay and sandy material, and the facts that the Weald Clay is less 
sandy than the underlying Ashdown Sands and that current bedding 
frequently occurs, are characteristic of lake as well as of delta 
deposits, if the lake is fed by streams with fairly swift current ; 
while the absence of rock-salt and gypsum is no proof that a lake 
did not exist. ‘The absence of marine bands from all but the upper 
part of the Wealden Series has been used as an argument against 
their being estuarine, but if this area was but the upper end of 
a delta their absence from the lower and presence in the higher 
horizon is but natural. De Lapparent held the estuarine view, “and 
he stated that the river in question is only one of several which 
entered the sea from the north. 
' G. W. Lamplugh, Mesozoic Rocks in Coal Explorations in Kent, p. 19. 
