TECTONIC+PLATES

= PLATE TECTONICS =

**The main features are:**

 * The Earth's surface is made up of a series of large plates (like pieces of a giant jigsaw puzzle).
 * These plates are in constant motion travelling at a few centimetres per year.
 * The ocean floors are continually moving, spreading from the centre and sinking at the edges.
 * **[|Convection currents]**beneath the plates move the plates in different directions.
 * The source of heat driving the convection currents is radioactive decay which is happening deep in the Earth.

Watch this clip to gain a better knowledge of how the plates move!!!!

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rift valleys are formed by the subsidence of a block of the Earth's [|crust] between two or more parallel [|faults]. Rift valleys are steep-sided and form where the crust is being pulled apart, as at [|mid-ocean ridges], or in the Great Rift Valley of East Africa. In cross-section they can appear like a widened gorge with steep sides and a wide floor. Africa's Great Rift Valley is a 6,000-mile crack (fissure) in the earth's crust, stretching from Lebanon to Mozambique. One of its most dramatic sections slices through East Africa, dividing Kenya into two [|segments].

Rift valleys occur as lithospheric plates are diverging, creating a gap between land masses which is being in filled with rising decompression melted basaltic magma and lava. did you know that tectonic plates cause volcanoes to erupt and tsunami's?