for the extraction of flints, it
necessarily happened that vast multitudes of unfinished or spoiled
implements and weapons were left on the ground, while the
better-formed specimens were for the most part taken away. This
conclusion is amply supported by similar localities in America, where
people well acquainted with many of the arts of life have left
quantities of strictly palaeolithic material. Wilson, Southall, and
other writers have accumulated so many examples of this that I think
the distinction of Palaeolithic and Neolithic ages must now be given up
by all investigators who possess ordinary judgment. A remarkable
instauce is the celebrated "Flint ridge" of Ohio, which was a great
quarry of flint for implements used by the ancient mound-builders, a
highly civilized race, as well as by the modern Indians. Here are
found countless multitudes of palaeolithic flint implements of all the
ordinary types, but which are merely the unfinished material of
workers capable of producing the most exquisite implements. There can
be scarcely a doubt that the palaeolithic implements of the European
gravels, in so far as they are the workmanship of man, are in like
manner merely the relics of old flint quarries.[120]

Possibly a more accurate measurement of time for particular regions of
the world might be deduced from the introduction of bronze and iron.
If the former was, as many antiquarians suppose, a local discovery in
Europe, and not introduced from abroad, it can give no measurement of
time whatever. In America, as the facts detailed by Dr. Wilson show,
while a bronze age existed in Peru, it was the copper age in the
Mississippi Valley, and the stone age elsewhere; and these conditions
might have co-existed for any length of time, and could give no
indication of relative dates. On the other hand, the iron introduced
by European commerce spread at once over the continent, and came into
use in the most remote tribes, and its introduction into America
clearly marks an historical epoch. With regard to bronze in Europe, we
must bear in mind that tin was to be procured only in England and
Spain, and in the latter in very small quantity; the mines of Saxony
do not seem to have been known till the Middle Ages. We must further
consider that tin ore is a substance not metallic in appearance, and
little likely to attract the attention of savages; and that, as we
gather from a hint of Pliny, it was probably first observed, in the
West