eet in thickness. The materials of the beds, at first a soft
mass like the ooze which the dredger brings up from the bottom
of the present ocean, became packed together in a solid mass.

Then disturbances affected this old sea bottom. It was raised, and
gravel, clay, and sand from some new shore were washed over the
bed of animal remains, burying it deeply. Continued movements of
the earth finally folded these rocks, which, as they were, squeezed
and broken, became warm. The heat and pressure started chemical
action in the decayed animal bodies, and particles of organic matter
were driven off in the form of oil and gas. These substances were
forced here and there through the fissures in the rocks. Part of
the products found a way to the surface and formed springs, while
other portions collected to form vast reservoirs in such porous
rocks as sandstone. The sulphur and mineral springs which occur
in oil regions tell us that this work of oil-making is still going
on.

The oil as it comes from the ground is usually brownish or greenish
in color, and much thicker than the refined product which we use
in our lamps. Some of the crude petroleum is thick and tar-like
in appearance, and when long exposed to the air turns to a solid
black mass called "asphaltum." This, when softened by heat and
mixed with sand, makes a valuable material for street pavement.

THE CLIMATE OF THE PACIFIC SLOPE

The western portion of the United States exhibits very interesting
climatic features. In California, for example, there may be found
every degree of temperature between tropic heat and arctic cold.
In the deserts of the southeastern portion of the state the air
is extremely dry, while in the northwest it rains nearly every
month in the year.

Upon the borders of Puget Sound the thermometer seldom falls below
the freezing-point, while southern Newfoundland, in the same latitude,
is marked by cold and snowy weather for at least six months of
every year. Southern California has the same latitude as central
Georgia, but its average temperature near the coast is but little
higher than that of Puget Sound, while it is warmer in winter and
cooler in summer than Georgia. The deserts of southern California
and Arizona are so hot that for four months of the year work in the
sun is almost impossible; yet the higher portions of the Sierra Nevada
mountains, but a short distance away, have an arctic climate. The
whole Pacific coast region has,