he surface of the water, that is horizontal, until
disturbed. Then they would be tilted in many directions. Hence it will
be easily seen why the seams in the rocks, especially in and near
mountainous regions, do not lie in a horizontal position after an
upheaval, but are found standing at all angles, up to a perpendicular.

Viewed from this standpoint, the solid portion of the old world has gone
all to pieces. Wherever there is a chain of mountains it marks a
breakage in the earth's crust, and these mountains are not all on the
land, but extend under the seas so deeply that they are unable to lift
their heads above the surface of the water. The earth is no longer
round, except in general outline, but broken up into all sorts of
shapes that give the varied conditions of landscape that we find
whichever way we turn.

There are but few volcanoes that are active in this age, while in former
times they extended for thousands of miles. We still have occasional
earthquakes, but undoubtedly they are very slight as compared with those
that shook the earth millions of years ago.

If, now, we study the constitution of the earth's crust so far as it has
yet been penetrated, we find it divided up into periods called Primary,
Secondary, and Tertiary. The primary period reaches down to the line
where the lowest forms of animal fossils begin to be found. This is
called the "Paleozoic" period, which means the period of "ancient life."
From here let us first go downward. Immediately under this lies a
stratum of "Metamorphic" rocks. To metamorphose is to change; and
metamorphic rocks are those which have been changed by heat or pressure
from their original formation. This class of rocks lie on top of what
are called "Igneous" rocks, which means that they have been formed by or
subjected to heat. All lava-formed rocks are igneous. They are
unstratified,--not in layers or strata, but in a formless mass,--and in
this they differ from water-formed rocks.

If there is a molten center to the earth these igneous rocks are
undoubtedly the offspring of this great internal furnace. The
metamorphic rocks were primarily igneous and are changed somewhat in
their structure by the lapse of time. For instance, marble is a
metamorphic limestone. The difference between common limestone and
marble is in its molecular structure--the way in which its smallest
particles are put together. They are both carbonates of lime. But the
marble is made up of little