Download The Earths interior overview

The Earth’s Interior: A Brief Overview
It is imperative to understand the earth's structure before you can understand tectonic
forces.
The earth's interior is neither all solid nor is it all molten. There are layers with a
different density, thickness and composition.
Furthermore the earth's crust is not one continuous layer. It is broken into many
sections known as plates. Some plates are quite small while others are quite large.
They all float and move on top of the molten asthenosphere. When they push together
and when they pull apart they create "tectonic forces". It is interesting to note; without
this liquid layer called the asthenosphere we would not experience earthquakes or
volcanoes.
 Inner Core: The deepest part of the earth (1512 miles deep) is a solid that
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contains both iron and nickel. It is because
of this that the centre of the earth is a
magnet, a compass. It generates a
magnetic field that protects the earth from
flying out of orbit.
Outer Core: Outside of the inner core lays
the outer core (1419 miles deep). This is
much like the inner core with the
exception that it is a liquid that contains
sulphur and oxygen (which lowers the
melting point).
Mantle: Occupying 1789 miles of the earth
is the magma (iron and magnesium) that
makes up the mantle. It is mostly solid
except the outer 200-300 Km which is
extremely hot and goopy; very plasticlike. This outermost liquid layer of the
mantle is referred to as the
asthenosphere.
Mohorovicic Discontinuity (MOHO):
Boundary between the mantle (asthenosphere) and the Lithosphere.
Lithosphere (crust): This is the top layer of the earth, which is basically
hardened mantle (magma). It contains two segments, the oceanic and
continental crusts. Note: this is the same crust, it just depends how thick it is
to determine if it is part of the Oceanic or Continental Crust. For instance, if
you drained all of the water from earth, then there would be one, giant
Continental Crust. Likewise, if you flooded everything, you'd have one, giant
Oceanic Crust.