CHAPTER XIII.
THE OVERLAP OF HISTORY.
THE OVERLAP OF HISTORY.
The Historic period constitutes the last phase of the series of changes which have been reviewed in our inquiry into early man and his place in the Tertiary period. It embraces the events recorded in history which are not only arranged in a linear series, but also possess a definite chronology in terms of years. It differs in this last respect from all the preceding geological periods, of which we know only that they followed one another in a definite order, but to which we cannot assign a date, because there is no standard of comparison to show the contemporaneity in different regions. We have seen in the last four chapters that there is reason for believing that one part of Europe