Cratons
A craton (Greek: κράτος kratos "strength") is an old and stable part of the continental lithosphere. 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 a few hundred kilometers into the Earth's mantle.
The term craton is used to distinguish the stable portion of the continental crust from regions that are more geologically active and unstable. Cratons can be described as shields, in which the basement rock crops out at the surface, and platforms, in which the basement is overlain by sediments and sedimentary rock.
The word craton was first proposed by the German geologist L. Kober in 1921 as "Kratogen", referring to stable continental platforms, and "orogen" as a term for mountain or orogenic belts. Later authors shortened the former term to kraton and then to craton.
Examples of cratons are the Slave craton in Canada, the Wyoming craton in the United States, the Amazonia craton in South America, the Kaapvaal craton in South Africa, and the Gawler craton in South Australia.