278 CORRELATION OF THE PREHISTORIC "FLOOR."
the present time, while, from other considerations, a value of
twice this amount is in the highest degree improbable. Indeed,
the lower value is perhaps in excess of the necessities of the case.31
If we said five thousand within a margin of error of fifteen
hundred on either side, we should probably be fairly safe. This 
would give time for the deposition of the tidal silts, and would
be in general agreement with the archaeological evidence. It
would also be within the keeping of tradition.
Another difficulty in considering whether the remains from
the Buried Prehistoric Surface should, or should not, be called
Neolithic, arises from the question of nomenclature. Before
we are in a position to consider this problem, we must first ask
the question : What is Neolithic ?
In this country, it is customary to consider the Neolithic age
to be a culture stage, subsequent to the Palaeolithic Period, in
which the working of metal was absolutely unknown. But if
we follow the records of discovery, we cannot help being struck
by the fact that at one Lake Dwelling or similar station after
another, that has been regarded as Neolithic, Bronze has sooner
or later turned up. There is a strong tendency in this country
to thereupon transfer such a station to the Bronze Age. And
this, in spite of the fact that it may still have far more in common
with those stations where no bronze has yet been found than
with those which belong to the fully developed Age of Bronze.
Thus the reality of the prehistoric succession becomes confused
or destroyed. It is somewhat disturbing to our conventional
classification to observe how frequently bronze of local manu-
facture ultimately turns up in working supposed Stone Age
sites.
I must confess that it seems to me that a pure and strict
Neolithic age, to the total exclusion of all knowledge of metal,
becomes a somewhat shadowy and uncertain quantity. The
prehistoric succession depends rather upon the development of
certain types, and the relative proportions in which they were
used, than in the absolute presence or absence of metal.
The question of Neolithic or Bronze Age is thus by no means
the simple one that it might at first sight appear. It raises at
once very wide questions of classification and nomenclature,
31 If it be thought that my estimate is too moderate, an even lower one will be found
in the new Memoir of the Geological Survey on the London District, by H. B. Woodward.
1909, p. 98.