Today's Word of the Day means...
the layer of the earth that underlies the continents and continental shelves; the thick part of the earth's crust that form large land masses
A hard, crisp covering or surface.
An outer layer or coating formed by the drying of a bodily exudate such as pus or blood; a scab.
|continental crust |
See under crust.
The solid, outermost layer of the Earth, lying above the mantle. ◇ The crust that includes continents is called continental crust and is about 35.4 to 70 km (22 to 43.4 mi) thick. It consists mostly of rocks, such as granites and granodiorites, that are rich in silica and aluminum, with minor amounts of iron, magnesium, calcium, sodium, and potassium. ◇ The crust that includes ocean floors is called oceanic crust and is about 4.8 to 9.7 km (3 to 6 mi) thick. It has a similar composition to that of continental crust, but has higher concentrations of iron, magnesium, and calcium and is denser than continental crust. The predominant type of rock in oceanic crust is basalt.
Note: The crust includes the continents and the ocean bottom and is generally estimated to be about five to twenty-five miles thick.
Note: The crust is made from relatively lightweight rocks that floated to the surface when the Earth was molten early in its history.