rearrangement. Thus the man whose leavings ought to form the layer
half-way up may have seen fit to dig a deep hole in the cave-floor
in order to bury a deceased friend, and with him, let us suppose, to
bury also an assortment of articles likely to be useful in the life
beyond the grave. Consequently an implement of one age will be found
lying cheek by jowl with the implement of a much earlier age, or even,
it may be, some feet below it. Thereupon the pre-historian must fall
back on the general run, or type, in assigning the different implements
each to its own stratum. Luckily, in the old days fashions tended to
be rigid; so that for the pre-historian two flints with slightly
different chipping may stand for separate ages of culture as clearly
as do a Greek vase and a German beer-mug for the student of more recent
times.

* * * * *

Enough concerning the stratigraphical method. A word, in the next place,
about the pre-historian's main sources of information. Apart from
geological facts, there are three main classes of evidence that serve
to distinguish one pre-historic epoch from another. These are animal
bones, human bones, and human handiwork.

Again I illustrate by means of a case of which I happen to have
first-hand knowledge. In Jersey, near the bay of St. Brelade, is a
cave, in which we dug down through some twenty feet of accumulated
clay and rock-rubbish, presumably the effects of the last throes of
the ice-age, and came upon a pre-historic hearth. There were the big
stones that had propped up the fire, and there were the ashes. By the
side were the remains of a heap of food-refuse. The pieces of decayed
bone were not much to look at; yet, submitted to an expert, they did