sion that here has been the
meeting ground of many distinct tribes and nations. "From such a
mixture, and over-population of the most desirable portions of the
country, would naturally result the formation of the hundreds of petty
tribes that existed in both Upper and Lower California when first known
to the Spaniards."<29>

In view of these facts, it is not strange that no advance in culture is
noticeable; and the grounds just mentioned may go far to explain why we
catch sight, here and there, of bits of customs, habits, and manners of
life which strangely remind us of widely distant people--though it will
not explain the presence of words of Malay or Chinese origin which are
claimed to exist.<30> What is known as the Eskimo trace is quite marked
in the physical characters and in the arts of the Californians.<31>
It is, probably, the continuance of the type of the primitive American
race.

It would naturally be interesting to know whether any date can be given
for the Pliocene Age, and so give us some ideas as to the antiquity of
man, if he were really here during that epoch. This, however, is one of
the most difficult questions to answer, and in the present state of our
knowledge incapable of solution. Approximations have, of course, been
made, and, as might be expected, vary greatly in results. When it was
acknowledged on all hands that on geological grounds the age of the
earth was certainly very great, many times the few thousand years
hitherto relied on, it is not strange that popular thought swung to the
other extreme, and hundreds of millions of years were thought necessary
to explain the series of changes which the geologists unfolded. This
demand for a greatly extended time was strengthened when the law of
the gradual evolution of life was expounded by the modern school of
naturalists, and as great a lapse of time as five hundred millions of
years was not deemed an extravagant estimate. Sir William Thompson has,
however, demonstrated that the time that has elapsed since the crust of
the earth became solidified can not be far from one hundred millions of
years, and consequently we know the time since the appearance of life
must be greatly less than that number of years.

Attempts have been made to estimate the length of time required to form
the sedimentary crust of the earth. The results are so divergent on this
point that it is best not to adopt any standard at present. Our views
on this matter are also de