H.. H. Howorth.—A Great Post-Glacial Flood. 363 
ossiferous débris,—or whether they occur in vast barren sheets over 
Central and Southern England, with neither shells nor bones,—we 
propose to show that the great bulk of these surface gravels may be 
integrated into a continuous series, and owe their present distribution 
to one common overwhelming cause. 
In regard to the High Level Marine Drift of which we wrote in the 
previous paper, it passes unmistakeably and insensibly into a similar 
drift without shells exactly like it in every respect save in the 
absence of these shells. For this drift also a marine origin has been 
generally adduced, and in fact every observer of any standing who 
has written about the beds, including notably Mr. Mackintosh, is 
agreed that the presence of the marine shells is an accident. The 
same transported boulders which have travelled from the same areas 
occur in both; the pebbles are similarly rounded and the sands are 
similarly laminated in places, while the beds are apparently hori- 
zontally continuous, nor is there any reason of any kind for doubting 
that they are contemporary. 
‘Near the summit level of the pass of Llanberis,” says Mr. 
Mackintosh, “some years ago, I saw a striking section of obliquely 
laminated sand and fine gravel, probably about 1000 feet above 
the sea-level. The extent to which the stones were rounded, the 
arrangement of the lamine and the position of the deposit (being 
away from any channel which could have conducted a fresh-water 
stream), all pointed to its being of marine origin, though I did not 
see any shells” (id. p. 557). 
Most writers, as Mr. Mackintosh says, including Ramsay and 
Etheridge, have observed the resemblance these beds (without 
shells) bear to what may be seen on a sea-beach. ‘The fact that the 
rounded pebbles found in the gravels of North Wales, which have 
come from Eskdale, in Cumberland, to North Wales, are found 
unrubbed at Eskdale itself, shows that the trituration took place 
en route, while the further fact that erratics have converged on this 
point both from Ireland and the Solway Firth, make it clear the trans- 
porting power was water, which could alone work along lines which 
are not parallel, in this way converging on one point. Again, Mr. 
Mackintosh remarks that the existence of the rounded gravel and 
sand deposits, with shells, at about the same level in different parts 
of North Wales, and likewise in England and Ireland, could scarcely 
have been the result of an accident (Journ. Geol. Soc. vol. xxxvii. 
p- 864). Quite so, but I would say further they could hardly be 
the result of icebergs or an ice-sheet, and can only be explained by a 
diluvial movement ona great scale. This is again testified by the fact 
that above the level of the shelly deposits rounded gravel and sand with 
shells would appear to be everywhere absent (id.). Finally, if we 
exclude ice, as we have assuredly given good reason for excluding 
it in a former paper, how else than by a violent movement of water, 
carrying with it great masses of debris and shingle, can we account 
for such a distribution of gravel as we find in Caernarvonshire ? 
“From Clynnog to Penmanmawr,” says Mr. Sharpe, “the whole 
western side of the Snowdon range is flanked by igneous rocks, 
