What is the crust.
Octavia
Perry
Hi again, Octavia:
The crust is the outermost layer of the earth (not counting the
atmosphere). We live on the top of the crust. The crust is relatively
cold and brittle compared to the layers that are deeper down. Continental
crust is made up of old rocks and it is 20-60 km thick. Oceanic crust
consists of young basalt, is about 5 km thick, and is presently forming at
mid-ocean ridges. These ridges are places where basalt magma comes up
from the upper mantle and cools. After a while the two sides of the ridge
pull apart, and soon new basalt comes up to again fill the crack.
Most introductory geology books have good diagrams to show how the crust relates
to the rest of the Earth, how
continental
and
oceanic crust
compare, and how
oceanic crust is created at mid-ocean ridges. There is also a CD-ROM about
plate tectonics that you can buy and play on your computer to learn more.
Sincerely,
Scott Rowland, University of Hawaii
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