PART II.

PAE AND,

  

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ALTHOUGH water occupies much the larger portion of the earth’s surface, yet, when compared with
the entire volume of the globe, its quantity is comparatively insignificant ; for the mean depth of the
ocean probably does not exceed two and one-third miles, and underneath this lies the solid crust,

with its heated interior.

The crust and heated interior are composed of a variety of simple and compound substances. Simple
or elementary substances are those which have never been separated into components. Compound
substances are those which are composed of two or more simple or elementary substances combined

under the influence of the chemical force.

— S. £8 KGW RB $$

SEC rtowe
THE INSIDE OF THE EARTH.

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CHAPTER I.
The Heated Interior.

30. The Proofs of the Earth’s Original Fluidity
or fused condition through heat are—

1.) Its Spherical Shape, which is the shape
the earth would have taken had it been placed
in space when in a melted condition. This is
the shape of nearly all the heavenly bodies.

22

.

(2.) The fact that the rocks which were first
formed give evidence by their appearance of
having been greatly heated. These rocks are
generally highly crystalline.

(3.) The general climate of the earth during
the geological past was much warmer than at
present.

Very little of the internal heat now reaches the surface.

According to Poisson, all that escapes would raise the mean
annual temperature only #,th of a degree Fahr.