Cratons

A craton (pronunciation: /ˈkreɪtɒn/, /ˈkrætɒn/, or /ˈkreɪtən/; from Greek: κράτος kratos "strength") is an old and stable part of the continental lithosphere, where the lithosphere consists of the Earth's two topmost layers, the crust and the uppermost mantle. Having often survived cycles of merging and rifting of continents, cratons are generally found in the interiors of tectonic plates. They are characteristically composed of ancient crystalline basement rock, which may be covered by younger sedimentary rock. They have a thick crust and deep lithospheric roots that extend as much as several hundred kilometres into the Earth's mantle.

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