Supercontinent

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In geology, a supercontinent is a land mass comprising more than one continental core, or craton. The assembly of cratons and accreted terranes that form Eurasia<ref>And to a lesser extent, the Americas, if taken as a whole</ref> qualifies as a supercontinent today.

1 History
2 Geology
- 2.1 Incomplete list of major past supercontinents
- 2.2 Incomplete list of supercontinents
3 Notes
4 External links

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History

Most commonly, paleogeographers employ the term supercontinent to refer to a single landmass consisting of all the modern continents. The earliest known supercontinent, Rodinia, broke up roughly 750 million years ago. One of the fragments included large parts of the continents now located in the southern hemisphere. Continental drift brought the fragments of Rodinia back together in a different configuration during the late Paleozoic era, forming the best-known supercontinent, Pangaea. Pangaea subsequently broke up into the northern and southern supercontinents, Laurasia and Gondwana.

Modern studies have suggested that supercontinents form in cycles, coming together and breaking apart again, through plate tectonics, very roughly about every 250 million years. Recently, Drs. John J. Rogers and M. Santosh have proposed the existence of an older supercontinent, Columbia, which formed and broke up during a period of 1.8 to 1.5 billion years (1.8-1.5 Ga) ago.

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Geology

Supercontinents block the flow of heat from the Earth's interior, and thus cause the asthenosphere to overheat. Eventually, the lithosphere will begin to dome upward and crack, magma will then rise, and the fragments will be pushed apart. It is currently a matter of some debate as to how the supercontinents reform, whether or not continental drift makes them re-join after travelling around the planet, or if they drift apart and then back together again.

In other areas of study such as history and geography, land masses connected with an isthmus are also considered supercontinents or just continents, such as the Americas. Some historians call the combined land mass of Africa and Eurasia the supercontinent Africa-Eurasia, but it is not a geological supercontinent.

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Incomplete list of major past supercontinents

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Incomplete list of supercontinents

In reverse-chronological order (stratolithic order) comprising nearly all land at the time.

Pangaea Ultima or Amasia (~250 – ~400 million years from now)
Eurasia (present-day supercontinent)
Pangaea (~300 – ~180 million years ago)
Pannotia (~600 – ~540 million years ago)
Rodinia (~1.1 – ~750 million years ago)
Columbia (~1.8–1.5 Ga ago)
Kenorland (~2.45 – ~2.10 Ga ago)
Ur (~3 Ga ago, though probably not a supercontinent; but still however, the earliest known continent. Ur, however, was probably the largest, perhaps even the only continent three billion years ago, so one can argue that Ur was a supercontinent for its time, even if it was smaller than Australia is today). Still an older rock formation now located in Greenland dates back from hadean