various parallel ranges of the
Great Basin to Owens Valley at the eastern base of the Sierra Nevada
mountains. This is the highest and longest continuous mountain range
in the United States. For a distance of more than one hundred miles
its elevation is from twelve thousand to over fourteen thousand
feet.

[Illustration: FIG. 23.--EASTERN FACE OF THE SIERRA NEVADA MOUNTAINS

Formed by a great fracture in the earth's crust]

Owens Valley was in 1872 the centre of one of the most severe and
extensive earthquakes ever recorded in the United States. The little
village of Lone Pine, situated in the valley below Mount Whitney,
was utterly demolished, twenty people were killed and many injured.
A portion of the valley near the village sank so low that the water
flowed in and formed a lake above it. The land was so shaken up
that the fields of one man were thrust into those of his neighbor.
For a distance of several hundred miles to the north along the base
of the mountains the earth was fractured, and bluffs from ten to
forty feet high were formed as a result either of the dropping of
the surface of the valley upon the eastern side, or of the raising
of the mountains upon the west.

This slipping of the earth which gave rise to the earthquake bluffs
was the most recent of a long series of similar events which have
raised the precipitous eastern wall of the Sierra Nevada mountains
to a height of two miles above Owens Valley. If you will go out
into the centre of the valley and look west toward the mountains,
you will see three bluffs or scarps. The first, which is twenty
feet high, was made at the time of the last earthquake; the second,
known as the Alabama Hills and rising about four hundred feet, was
formed at an earlier time; the third, rising back of the others,
is that of the main Sierra.

Similar cliffs appear at the bases of other ranges of mountains
in the Great Basin. Springs abound along these fractures in the
earth, for the surface waters have an opportunity to collect wherever
the rocks are broken. Numerous fertile valleys mark the line of
earthquake movements, for the broken rocks and abundant springs
favor rapid erosion.

Among the Coast Ranges of California there appears a series of
fractures in the earth which form a line nearly four hundred miles
long. They extend from a point near San Bernardino in a northwesterly
direction to the neighborhood of San Francisco. Severe earthquakes
have taken place alo