Download The Interior of the Earth

The Interior of the
Earth
What exactly is in there?
Of course we do not know for certain, but we are pretty
sure the Earth’s interior is made of several distinct
layers.
Starting from the outside, there is the relatively thin crust, the
very thick mantle, and then the outer core and inner core.
The lithosphere includes the solid crust and the solid uppermost layer of
the mantle.
(The lithosphere is broken up into tectonic plates.)
The asthenosphere is the semi-liquid layer of upper mantle.
(The plates are believed to flow slowly on top of the asthenosphere.)
The mantle is thick - it makes up about 84% of the volume of the
Earth.
And it is hot - it is believed that convection currents in the mantle
are what make the plates move.
The outer core and inner core are even hotter.
The outer core is liquid iron,
but the inner core – even though it is hotter – is SOLID iron.
Yes, solid – NOT liquid. Can you guess why?
How do you suppose
scientists know so much
about the interior of the
Earth?
The answer might surprise you.
Earthquakes!
Seismic waves actually.
(P and S waves, to be more specific.)
An understanding of the interior of the Earth helps us to
understand the driving force behind plate tectonics.
(Click on image for a video – 5:42)