What is Craton?
[[File:North america craton nps.gif|thumb|250px|The broad picture of the [[North American Craton]]]] [[File:Cratons West Gondwana and EAO.png|thumb|Cratons of West [[Gondwana]], which later became Africa and South America]] A '''craton''' is the oldest part of a [[continental plate]]. It is an old and stable part of the continental [[lithosphere]]. After surviving cycles of merging and rifting of continents, cratons are usually found in the interiors of [[tectonic plate]]s. They are composed of ancient [[crystalline]] [[Basement (geology)|basement rock]], which may be covered by younger [[sedimentary rock]]. They have a thick crust and deep roots that extend as much as several hundred kilometers into the Earth's [[mantle (geology)|mantle]].<ref>{{cite book |last=Stanley |first=Steven M. |title=Earth system history |url=https://archive.org/details/earthsystemhisto0000stan |location=New York |publisher=W.H. Freeman |year=1999 |isbn=0-7167-2882-6 |pages=[https://archive.org/details/earthsystemhisto0000stan/page/297 297]–302}}</ref> ''Cratonic lithosphere is much older than oceanic lithosphere'' – up to 4 billion years versus 180 million years.<ref>{{cite journal |url=http://www.sciencenews.org/view/feature/id/66927/title/Continental_Hearts |title=Continental hearts - Science News |last=Petit |first=Charles | journal=Science News | volume=178 | issue=13 |pages=22–26 |date=18 December 2010 |issn=0036-8423 |publisher=Society for Science & the Public |access-date=2011-01-08 }} p25</ref> 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. Cratons are subdivided geographically into geologic '''provinces'''. A geologic province is an area with common geologic properties. == References == {{Reflist}} [[Category:Plate tectonics]]