s are found, and the relative age of that stratum is known, it is
easy to estimate the relative age of man.

Whether man existed prior to the glacial epoch is still in doubt. Some
anthropologists hold that he appeared at the latter part of the
Tertiary, that is, in the Pliocene. Reasons for assumption exist,
though there is not sufficient evidence to make it conclusive. The
question is still in controversy, and doubtless will be until new
discoveries bring new evidence. If there is doubt about the finding of
human relics in the Tertiary, there is no doubt about the evidence of
man during the Quaternary, including the whole period of the glacial
epoch, extending 500,000 years into the past.

The relics of man which are found in the drift and elsewhere are the
stone implements and the flakes chipped from the flint as he fashioned
it into an axe, knife, or hatchet. The implements commonly found are
arrow-heads, knives, lance-heads, pestles, etc. Human bones have been
found imbedded in the rock or the sand. Articles made of horn, bones
of animals, especially the reindeer, notched or cut pieces of wood have
been found. Also there are evidences of rude drawings on stone, bone,
or ivory; fragments of charcoal, which give {76} evidence of the use of
fire in cooking or creating artificial heat, are found, and long bones
split longitudinally to obtain marrow for food, and, finally, the
remnants of pottery. These represent the principal relics found in the
Stone Age; to these may be added the implements in bronze and iron of
later periods.

A good example of the use of these relics to determine chronology is
shown in the peat bogs of Denmark. At the bottom are found trees of
pine which grew on the edges of the bog and have fallen in. Nearer the
top are found oak and white birch-trees, and in the upper layer are
found beech-trees closely allied to the species now covering the
country. The pines, oaks, and birches are not to be seen in that part
of the country at present. Here, then, is evidence of the successive
replacement of different species of trees. It is evident that it must
have taken a long time for one species thus to replace another, but how
long it is impossible to say. In some of these bogs is found a
gradation of implements, unpolished stone at the bottom, polished stone
above, followed by bronze, and finally iron. These are associated with
the different forms of vegetable remains.

In Europe stone