Plate+Tectonics-+MAGMA

The Earth's center is super heated causing a flow of molten rock called magma to circulate. The magma becomes exposed as lava when it reaches the surface.

http://www.pbs.org/wgbh/nova/volcanocity/images/anat-magma-l.jpg

Article- http://www.enotes.com/earth-science/magma

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