ng this line since the country was settled.
The pressure and grinding of the earth upon opposite sides of the
fissures has formed long low ridges of earth. Small valleys have
been blocked, and the old stage road from Los Angeles to Bakersfield,
which followed the course of the fissures for a number of miles,
has been almost obliterated.

[Illustration: FIG. 24.--ELIZABETH LAKE, CALIFORNIA

Occupying a valley primarily due to earthquake movements]

Hundreds of cliffs and mountain scarps throughout the West have
come into existence as the results of movements such as we have been
describing. Where the disturbances have been recent the mountains
are bold and picturesque. Those produced in earlier times are in many
instances so worn away that it is difficult to tell with certainty
how they were made.

THE LAST VOLCANIC ERUPTIONS IN THE UNITED STATES

There are more volcanoes in our country than is generally supposed.
Some are very small and some rank among the greatest of mountain
peaks, but all together there are many hundreds, perhaps thousands,
of them. At present they are all silent and apparently dead. We
are accustomed to speak of them as extinct volcanoes, but of this
we must not be too sure.

They stand dark and cold, giving no clue to the nature of the forces
which made them, except perhaps by the presence of an occasional hot
spring and the appearance of the rocks of which they are composed.
The slag-like character of these rocks we have learned to associate
with intense heat. Some of these volcanoes are very old and have
been nearly worn away; others are new and almost as perfect as
when they were first made.

Where shall we go to find these volcanoes? Are there any upon the
Atlantic coast or neighboring highlands? Though you may travel
over all that portion of our country, you will find none, although
you will discover in places, as for instance in the palisades of
the Hudson, lavas which came from very ancient volcanoes, worn
down so long ago that their very sites are lost to view.

If we search the Mississippi basin we find there even fewer traces
of volcanic action than upon the eastern highlands. The greater
portion of the vast area embraced by the Mississippi River and its
tributaries has had a very uneventful history, although at times
earthquakes may have occurred and the sky may have been darkened
by ashes from eruptions in distant parts of the earth.

[Illustration: FIG. 25.--FISSURE I