A supercontinent is a large area of land which has more than one continental core, or craton. They are formed by continental plates coming together. Continental plates have periodically collided and assembled in periods of orogeny (mountain-building) to form supercontinents. The cycle of supercontinents forming, breaking up, separating, and re-forming through plate tectonics happens about every 2000 million years.
Eurasia is certainly a supercontinent, but the Americas are usually thought of as separate continents. Even more clearly, Gondwana and Laurasia were supercontinents formed by the breakup of the global supercontinent Pangaea.
Throughout Earth's history, there have been many supercontinents. In order of age (oldest to newest), the ancient supercontinents were:
|Supercontinent name||Age (Ma)||Period/Era Range||Comment|
|Vaalbara||3,636–2,803||Eoarchean-Mesoarchean||Also known as a supercraton or just a continent|
|Ur||2,803–2,408||Mesoarchean-Siderian||Known as both a continent and a supercontinent|
|Kenorland||2,720–2,114||Neoarchean-Rhyacian||The continents may have also formed into two groupings Superia and Sclavia|
|Arctica||2,114–1,995||Rhyacian-Orosirian||Not generally known as a supercontinent, depending on definition|
|Atlantica||1,991–1,124||Orosirian-Stenian||Not generally known as a supercontinent, depending on definition|
|Gondwana||550–175||Ediacaran-Jurassic||From the Carboniferous, formed part of Pangaea, not always known as a supercontinent|
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