5
The ages have been so named from the principal material
of which the implements were made in the several stages of
culture through which man appears almost universally to have
passed.
The lapse of time which these four periods embrace is
very uncertain ; the time occupied by the last three, extends
back only so far as the present geographical conditions of
Britain. The period required, however, for the Palaeolithic
Age is vastly greater, and carries us back to a time when
these Islands were part of the continent of Europe and
experienced extremes of climatic change. (See fig. 1.)
PALAEOLITHIC PERIOD.
The earliest generally accepted evidence of man's appear-
ance is found in the flint implements of the Plateau and River
Gravels and in Caves and Rock-shelters. It must not be con-
sidered, however, that these remains mark man's earliest appear-
ance on the earth. It is quite probable that he is of much older
origin, though the evidence of this will possibly be found in some
part of the world where the climate was more favourable to
primitive existence than in Britain.
Stones appear to have been the first implements used by
man of which any trace has been found. At first natural forms
were selected, unshaped by artificial means and used simply in
the grasp of the hand. The blows of such rude implements on
hard substances would produce fractures and flakes, which in
time would suggest chipping by design, in order to produce an
implement of desired form with a superior cutting edge. The
flakes struck off in this process were also found to be useful tools
and came to be shaped and used for a variety of purposes.
Implements were, no doubt, made from wood and bone during
this age, but have not survived the geological changes that have
occurred, and which deposited the gravels in which these early
flint tools are found. These gravels were deposited in the beds
of former river valleys, and they now remain "terracing" the
face of the hills and looking down on younger rivers which
have eroded valleys far below the level of these older river beds.