Their contents and position indicate for them a date posterior to that of the great extinct mammals, but prior to the domesticated.

Some of these, it is said, cannot be less than one hundred thousand years old.
The lake-dwellings in Switzerland--huts built on piles or logs, wattled with boughs--were, as may be inferred from the accompanying implements, begun in the Stone age, and continued into that of Bronze.

In the latter period the evidences become numerous of the adoption of an agricultural life.
It must not be supposed that the periods into which geologists have found it convenient to divide the progress of man in civilization are abrupt epochs, which hold good simultaneously for the whole human race.
Thus the wandering Indians of America are only at the present moment emerging from the Stone age.

They are still to be seen in many places armed with arrows, tipped with flakes of flint.

It is but as yesterday that some have obtained, from the white man, iron, fire-arms, and the horse.
So far as investigations have gone, they indisputably refer the existence of man to a date remote from us by many hundreds of thousands of years.