nce. The scene
completely changes, when the misty curtain of the past again rises and
allows us to continue our investigations into primitive times.

We would naturally expect to find everywhere, connecting links between
these two ages--the culture of the one gradually changing into the
culture of the other. This, however, is not the case. The line
of demarkation between the ages is everywhere plainly drawn; and,
furthermore, we are learning that a very long time elapsed between the
departure, or disappearance, of the Paleolithic tribes, and the arrival
of their Neolithic successors. This is shown in a great many ways, and
we will notice some of them. We learn that Neolithic man occasionally
used caves as a place of habitation. In such cases there is nearly
always a thick layer of stalagmite between the strata containing the
Paleolithic implements and the Neolithic strata--though this stalagmite
is unmistakable evidence of the lapse of many years, we can not
determine how many, as we do not know the rate of formation.

This lapse of time is shown very plainly when we come to consider the
changes wrought in the surface features of the country by the action of
running water. We know that rain, running water, and frost, constituting
what we call denuding forces, are constantly at work changing the
surface of a country. We know that, in general, this change is slow. But
great changes have been wrought between these two ages.

In the British Islands, we know that the rivers had time to very
materially change the surface features of the land. The important rivers
of Scotland had carved out channels one hundred feet deep in places; and
along their courses, especially near their mouths, had plowed out and
removed great quantities of glacial material--forming broad flats which
became densely wooded before Neolithic man made his appearance on the
scene. In some cases the entire surface of the land had been removed,
leaving only knolls and hills of the old land surface. Examples of
this occur on the east coast of England, and in what is known as the
Fen-lands. The final retreat of the glaciers must have left the country
covered with _debris._ After this had been largely denuded, the country
became densely wooded. It was not until these changes had taken place,
that Neolithic man wandered into Europe.<3>

But still another ground exists for claiming a long interval between
these two ages, namely, the great changes that took plac