270 CORRELATION OF THE PREHISTORIC "FLOOR."
Thus the archaeological evidence is at least not contradictory
to the idea that this ancient surface belongs to a definite horizon
all round the southern parts of Britain.
At the same time, some caution is undoubtedly needed
here. For, although, in my opinion, the commonest submerged
forest of our coasts belongs to this definite stage, yet it must not
be forgotten that there are many other peats with associated
forest growths, which belong to very different horizons, some
dating from the age of the Mammoth, others coming down to
much later times. In order to give it a definite name to dis-
tinguish it from the other surfaces, I propose, for reasons pre-
sently to be given, that the Buried Prehistoric Surface should be
called the "Lyonesse" surface.
III.—THE EVIDENCE OF SUBMERGENCE.
Some writers23 have endeavoured to explain the "submerged
forests," without calling in any change in level, by supposing
that the forests grew on low-lying land protected behind sand
banks, and that when these gave way the forests became sub-
merged. Or else, upon another theory, that the soil under-
lying the peat and forest beds has been eroded by the passage
of subterranean water so as to cause the peats to founder down
and appear to occupy a lower position than that to which they
actually belong.24
If either of these theories were substantiated, it would be
impossible to attempt to correlate the buried surfaces of different
localities with each other. The phenomenon of the submerged
forests would be one of local accident only, and they might be
—indeed, would be—of different ages at different places.
If, on the other hand, the submerged forests be due to a
general and wide-spread submergence of the country, then it
may be possible to correlate the ancient surfaces, as seen at
different places, with each other. The archaeological evidence
points to the conclusion that the buried surfaces in East Essex
and in Devonshire, which are on about the same level, were
also submerged at approximately the same date. Then, if the
submergence was a general one, it is a fair presumption to assume
that other surfaces at the same levels, which are seen at inter-
23 Professor Sucss is the foremost exponent of these views, but they have also been
advocated by many other writers.
24 W. Shone, Quart. Journ. Geol. Soc. vol. xlviii. (1892), p. 96.