Earth's Structure - How Many Licks Does it Take to Get to the Center?
Earth's Crust
The
first layer encountered when investigating the Earth is the
crust.
What do you think the crust is like? Well it's just like it sounds, crusty!
It is the thin outer layer of the Earth and as you know from everyday walking,
it is solid and rocky. When Earth was just starting to form it was a huge,
hot ball of molten rock. Gradually the lighter materials, Silicon, Aluminum,
Magnesium and Oxygen rose to the surface and cooled to form the crust. This
is demonstrated by
observing oil and water after they are shaken up. Drag
your mouse over the link to open the QuickTime video in a new window. Close
the window to return to this page. It now makes up only one percent
of earth's mass. The continental crust is thicker than the oceanic crust.
It can range from 25 km thick at the edges to 70 km thick near the center.
The oceanic crust on the other hand is only about 7 km thick and considerably
more dense. The crust and the uppermost part of the mantle make up the lithosphere,
a solid region that is broken into plates. It is about 65 to 100 km thick.
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