Imagine you could travel from one point on Earth
straight through the center of the planet and out
the other side. Your journey would be nearly
12,870 kilometers (8,000 miles).
Along the way, you'd pass through all of the
The rocky surface of the Earth is a thin outer
shell, much thinner than the other layers.
The land that we see, or continental crust, is
about 30 kilometers (19 miles) thick. Under the
sea, oceanic crust is much thinner (8 to 10
kilometers, or 5 to 6 miles thick), but it's also
The Earth's crust and the top part of the mantle
are broken into ten large plates and many
Most plates are made of both continental and
The crust floats on a thick layer of rock, almost
100 times thicker than continental crust.
The solid rock isn't like the rock we know.
Extreme heat makes it move in circles.
It flows very, very slowly, but it's enough to
cause the plates above it to move over long
periods of time.
The plates move about 8 centimeters (3 inches)
The core is even thicker than the mantle.
It's made of a liquid metal outer core that flows
around a solid metal inner core.
The motion in the outer core creates a magnetic
field around the Earth. It's the same field that
makes a compass work!
The core gives off incredible heat, which is one of the
driving forces that causes the mantle to flow.