pic Mountains formed an island. The broad and fertile
Willamette Valley was but an arm of the sea, somewhat like Puget
Sound to-day. The body of water which once filled this valley has
been called Willamette Sound. The ocean overspread the low Oregon
coast, and reached far up the valleys of the Umpqua and Rogue rivers.
But the boundaries of the Klamath Mountains were not greatly changed,
for in many places they rise quite abruptly from the present shore
line.

All the large valleys of California were flooded, including the
San Joaquin-Sacramento valley, which was then a great sound, open
to the ocean in the region of the present Strait of Carquinez.
The Coast range was broken up into islands and peninsulas. The
islands off the coast of southern California are high and therefore
were not entirely submerged. The Gulf of California spread over the
Colorado Desert, while from the west the water penetrated inland
over the plain of Los Angeles to a point beyond San Bernardino, so
that at the San Gorgonio pass only a narrow neck of land connected
the San Jacinto Mountains and the Peninsula Range with the mainland.

If California had been inhabited at this time, the state would
not have been noted for orchards and grain-fields, but rather for
its mineral wealth. There would have been comparatively little
low land fit for cultivation, but the mountains, where almost all
the precious metals are found, would have appeared nearly as they
do to-day.

The surface of the earth may be divided into the ocean basins and
the continental masses which rise above them, but we must not make
the mistake of thinking that the shore line always corresponds
with the border of the continental masses. We have learned that
the land is almost always moving slowly up or down, so that the
shore is continually changing back and forth. At one time the shore
line may be far within the borders of the continent, as we have
seen was once the case upon our Pacific coast; at another time,
if the land should rise, the shore line might coincide with the
real border of the continent. By the real border of the continent
we mean the line along which the earth slopes down steeply to the
abysmal depths of the ocean.

It is an interesting fact that outside the present shore line of
California there is a submerged strip of the continent varying
from ten to one hundred and fifty miles in width. This strip of
land is like a bench upon the side of the continent, and