INTERNAL STRUCTURE OF EARTH
The Earth is composed of four different layers. The crust
is the layer that you live on, and it is the most widely studied and understood.
The mantle is much hotter and has the ability to flow. The outer core
and inner core are even hotter with pressures so great you would be
squeezed into a ball smaller than a marble if you were able to go to the center
of the Earth!
The Crust
The Earth's Crust is like the skin of an apple. It is
very thin in comparison to the other three layers. The crust is only about 3-5
miles (8 kilometers) thick under the oceans (oceanic crust) and about 25
miles (32 kilometers) thick under the continents (continental crust).
The crust
is composed of two rocks. The continental crust is mostly granite.
The oceanic crust is basalt. Basalt is much denser than the
granite. Because of this the less dense
continents ride on the denser oceanic
plates.
The Mantle
The Mantle is the largest layer of the Earth. The middle
mantle is composed of very hot dense rock that flows like asphalt under a
heavy weight. The movement of the middle mantle (asthenosphere) is the
reason that the crustal plates of the Earth move.
The Outer Core
The core of the Earth is like a ball of very hot metals. The outer
core is so hot that the metals in it
are all in the liquid state. The outer core is composed of the melted metals of
nickel and iron.
The Inner Core
The inner core of the Earth has temperatures and
pressures so great that the metals are squeezed together and are not able to
move about like a liquid, but are forced to vibrate in place like a solid.
The Layers
of the Earth
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