its position of not less than three or
four thousand feet of perpendicular depth, and this surprising series
of changes is not peculiar to one locality, but the whole slope of
the Sierras, through the gold region, is the scene of similar volcanic
outflows and subsequent remodeling of the surface into a new series of
reliefs and depressions."<5>

Illustration of Imaginary Section of Table Mountain.-------

In order to fully realize the change here spoken of, an imaginary
section of Table Mountains is here presented. Here we see the two
valleys on the sides, and the mass of lava covering the top of the
mountain. The dotted lines represent the position of the old line of
hills, which must once have inclosed the valley down which coursed the
fiery torrent.

We require to dwell on this, fact before we can fully understand its
meaning. The "eternal hills," two and three thousand feet in height,
have been completely washed away, and where they stood is now a deep
valley. But the old valley, protected by its stony covering, is now a
mountain ridge; and this, we are told, is not a solitary instance, but
the entire surface of the country has been thus denuded. We stand in awe
before the stupendous results, which nature, working through vast cycles
of time, has accomplished.

But if this lava flow took place in a pre-existing valley, we ought to
find under the rocky covering beds of gravel, rolled stones, and other
_debris_ peculiar to a river bed. Such, in fact, we do find extended
along directly underneath the lava, about fifteen hundred feet above the
general level of the country. These old river gravels are found to be
very rich in gold, and miners have tunneled into them in numerous places
in search of the valuable metal. In order to determine the geological
age of these gravels, and subsequent lava flow, a careful examination of
portions of plants and bones of animals found therein has been made. The
plants are pronounced by competent authority<6> to be Pliocene, totally
distinct from any specimens now growing in California. The animal
remains are rhinoceroses, camels, and an extinct species of horse. The
age of these gravels is, therefore, pronounced to be Pliocene. We would
say in this connection that the auriferous gravels of California have
been the object of a very careful research by Prof. Whitney. He adds
to his conclusions that of another of the State geologists. We need not
give in detail his arguments, but