Oceanic crust is the part of Earth's lithosphere that surfaces in the ocean basins. Oceanic crust is primarily composed of mafic rocks, or sima, which is rich in iron and magnesium. It is thinner than continental crust, or sial, generally less than 10 kilometers thick, however it is denser, having a mean density of about 2.9 grams per cubic centimeter.
Famous quotes containing the word crust:
“All civilization has from time to time become a thin crust over a volcano of revolution.”
—Havelock Ellis (18591939)