A craton (Greek kratos; "strength") is an old and stable part of the continental crust that has survived the merging and splitting of continents and supercontinents for at least 500 million years. Some are over 2 billion years old. Cratons are generally found in the interiors of continents and are characteristically composed of ancient crystalline basement crust of lightweight felsic igneous rock such as granite. They have a thick crust and deep roots that extend into the mantle beneath to depths of 200 km.
The term craton is used to distinguish the stable interior portion of the continental crust from such regions as mobile geosynclinal troughs, which are linear belts of sediment accumulations subject to subsidence, or downwarping. The extensive central cratons of continents may consist of both shields and platforms, and the crystalline basement. A shield is that part of a craton in which the usually Precambrian basement rocks crop out extensively at the surface. In contrast, the platform of the basement is overlain by horizontal or subhorizontal sediments.
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.