CORRELATION OF THE PREHISTORIC "FLOOR." 271
mediate places, were also submerged at about the same time,
And further, it may be remarked that if, as appears to be the
case, this submergence was a considerable one, it is not likely
that local accidents (such as the protection afforded by sand-
banks) would modify by any considerable period of time the
date of submergence of the same level at different places. The
greatest chance of such local interference with the general
phenomenon would undoubtedly be found at places situated
at the heads of the estuaries which were the farthest from the
open sea-board.
It certainly appears to me that the theory of local accident
is inadequate to account for the position of the submerged
forests. Apart from the difficulty of explaining the existence
of peat beds, intercalated between fresh-water silts, at depths
of fifty feet or more below sea level, there is also the physical
evidence of the submerged river channels, the "drowned valleys"
of American geologists, to be taken into account. The sub-
merged forests in general, and the Buried Prehistoric [" Lyonesse "]
surface in particular, are intimately associated with the deep
river channels. These deep channels were certainly excavated
at a time when the land stood at a much higher elevation re-
latively to the sea than it does to-day. The series of pre-
historic deposits often form an integral part of the former
marsh beds of these river valleys ; and these deep river valleys
have most unquestionably been submerged.
The level of the Buried Prehistoric Surface is too low, and it is
too widely spread and continuous in its distribution to be ex-
plicable without inferring a considerable change in level.25 In
fact, I think there can be no doubt that it forms, broadly speaking,
a well-defined horizon, and represents a definite event in the
recent geological history of the country.
IV.—THE SUCCESSION OF RECENT DEPOSITS IN
EAST ESSEX AND THE PREHISTORIC REMAINS
THEY CONTAIN.
In a previous communication to this Society I gave some
account of the conclusions at which I had arrived from an
examination of the marsh deposits of Eastern Essex.26 In this
25 Sir A. Geikie, Quart. Jour. Geol. Soc., vol. lx. (1904), Proc, p. xcviii.
26 S. H. Warren, "Notes on the Palaeolithic and Neolithic Implements of East Essex,"
Essex Naturalist, vol. xvi. (1908), p. 46.