Lithosphere
From Freepedia
The lithosphere (from the Greek for "rocky" sphere) is the solid outermost shell of a rocky planet. On the Earth, the lithosphere includes the crust and the uppermost layer of the mantle (the upper mantle or lower lithosphere) which is joined to the crust.
The distinguishing characteristic of the lithosphere is not composition, but its flow properties. Under the influence of the low-intensity, long-term stresses that drive plate tectonic motions, the lithosphere responds essentially as a rigid shell, while the asthenosphere behaves as a slightly viscous fluid. Both the crust and upper mantle float on the more plastic asthenosphere. The crust is distinguished from the mantle, and hence the upper mantle, by the change in chemical composition that takes place at the Moho discontinuity. The thickness of the lithosphere varies from around 1.6 km (1 mi) at the mid-ocean ridges to approximately 130 km (80 mi) beneath older oceanic crust. The thickness of the continental lithospheric plates is probably around 150 kilometers (93 mi).
As the cooling surface layer of the Earth's convection system, the lithosphere thickens over time. It is fragmented into relatively strong pieces, called tectonic plates, which move independently relative to one another. This movement of lithospheric plates is described as plate tectonics.
The lithosphere is the outermost part of the solid earth. It includes Earth's surface. The lithosphere is made up of plates. These plates move against each other, causing some regions of Earth's surface to rise and others to fall. The rise and fall of Earth's surface under the oceans can have major effects on coral reefs. Volcanoes can affect coral reefs in a different way. Although volcanoes have their sources deep in Earth's interior, they penetrate through the lithosphere. There are two types of lithosphere:
