l ask how we can know so much about the past. It is
true that no one was here to witness the events which are supposed
to have taken place. But Nature has left a record of her doings
which we have only to see and understand in order to learn with
certainty many things which happened in the far distant past.

Too many of us go through life seeing and understanding almost
as little of the world about us as if we were blind. Our early
ancestors were obliged to understand many things about Nature and
to cultivate clear and close observation for the sake of
self-preservation. The very life of the savage depends upon the
training of his eyes. He must be able to tell the meaning of a
distant object or an indistinct trail, for his enemies may have
passed that way recently. If we could bring the sharp eyes of the
savage to our aid, the world would mean much more to us.

In order to learn something of the history of the Pacific shore
line, we must see what the waves are doing at the present time.
The projecting points of land are being worn away (Fig. 33). The
waves form the cliffs against which they beat, and sometimes, as
they eat their way slowly into the land, they cut off portions
and leave them standing alone as islands.

The pebbles and boulders (Fig. 34) were once angular fragments
torn from the cliff. They have been washed about and hurled against
the solid rock until they have been worn smooth; and the cliff
in turn has had a cave ground out at its base. Above the lower
cave there is a remnant of a second one, with pebbles upon its
floor. This was made when the land stood ten feet lower than at
present.

As the waves wear away the loose earth and the solid rock below
it, moving the cliffs inland, they leave a comparatively smooth
surface which is partly exposed at low tide. The fact that this
surface is not marked by stream channels, as is the land, helps
us to realize the great difference between the irregular surface
of the latter and the plain-like character of the ocean floor.

[Illustration: FIG. 33.--POINT BUCHON, CALIFORNIA

The waves are eating their way into the land]

Along the whole coast of California there are many old sea beaches
and cliffs which the waves abandoned long ago. The highest of these
beaches lies so far up the slopes of the mountains bordering the
ocean that it makes us wonder what the geography of California
could have been like when the region was so deeply submerged.

The lowest