[krey-ton] 
| a relatively rigid and immobile region of continental portions of the earth's crust. |
| cra·ton (krā'tŏn') n. A large portion of a continental plate that has been relatively undisturbed since the Precambrian era and includes both shield and platform layers. [German Kraton, from Greek kratos, power; see kar- in Indo-European roots.] cra·ton'ic (krə-tŏn'ĭk) adj. |
craton
the stable interior portion of a continent characteristically composed of ancient crystalline basement rock. The term craton is used to distinguish such regions from mobile geosynclinal troughs, which are linear belts of sediment accumulations subject to subsidence (i.e., downwarping). The extensive central cratons of continents may consist of both shields and platforms. A shield is that part of a craton in which (usually) Precambrian basement rocks crop out extensively at the surface. By contrast, in a platform the basement is overlain by horizontal or subhorizontal sediments.
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