Lithosphere includes the crust (continental or oceanic) and outside of the upper mantle.Average thickness of lithosphere is about 100 km.Lithosphere floats on the lower layer of earth called asthenosphera. Asthenosphera is a weak layer, in the viscous state. Due to convection movements within asthenosphera, solid lithosphere is fragmented into parts called tectonic plates that move independently one of another. These movements are called tectonic movements.
The outside of the lithosphere includes the crust of earth. Oceanic crust, called Sima has a thickness of 5-10 km and is composed mainly of basalt rocks.
Continental crust, called Sial, has a thickness of 20-70 km and is composed of rocks less dense than oceanic crust.
Upper mantle is composed of solid material, consistent. Mantle differs substantially from the crust by chemical composition, mechanical properties, types of rocks and seismic characteristics.
Crust is mainly a product of melting of mantle rocks. Due to melting, incompatible chemical elements are separate, less dense materials rising to the surface .
Rocks in the mantle have larger amounts of iron and magnesium,and less silicon and aluminum than the crust.
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