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Layers of Earth Crust • • • • Outermost layer Thinnest under ocean Thickest under continent Crust + top of mantle = Lithosphere Crust density • Least dense overall layer • Oceanic crust (basalt) is more dense than • Continental Crust (granite) Crust composition • Solid rock—mostly silicon and oxygen • Oceanic crust—basalt • Continental crust--granite Mantle Position • Middle layer, thickest layer • Top portion called the asthenosphere Mantle Density •Density increases with depth of increasing pressure Mantle Composition • Hot softened rock • Contains iron (Fe) and magnesium (Mg) Core position • Inner layer • Consists of the outer and inner core Core density • Heaviest material; most dense layer Core composition • Mostly iron and nickel • Outer core—slow flowing liquid • Inner core--solid Thickness of Layers • Crust: (continental) 22-43 miles thick (1 % of Earth’s volume) • Mantle: 1,800 miles thick (84% of Earth’s volume) • Outer core: 1,400 miles thick • Inner core: 790 miles thick