Supercontinent
A supercontinent is a mass of land comprising more than one continent.
Since the definition of continent is arbitrary, the definition of supercontinent is also arbitrary (as is the definition of a subcontinent), but the term refers to a landmass containing more than one of the modern continents.
Present day supercontinents are Eurasia, Africa-Eurasia, and The Americas.
Most commonly, the term supercontinent is used to refer to a landmass consisting of all the modern continents. It was originally believed that a single supercontinent, Pangæa, had existed for a very long period of Earth's history. However more modern studies have shown that supercontinents form in cycles, coming together and breaking apart again, through continental drift, about every 250 million years.
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.
The supercontinent Rodinia broke up roughly 750 million years ago. One of the fragments included large parts of the modern southern hemisphere continents. Continental drift then brought the fragments together in a different configuration, resulting in another supercontinent, Pangæa, forming in the late Paleozoic. Pangæa broke up into the northern and southern supercontinents, Laurasia and Gondwana.
Recently Drs. Rogers and Santosh have proposed the existence of a yet older supercontinent, Columbia, that was formed and broken up during a period of 1.8 to 1.5 billion years (1.8-1.5 Ga) ago.
Lists of supercontinents
List of present supercontinents
Partial (incomplete) List of major past supercontinents
Partial (incomplete) list of supercontinents in reverse-chronological order (stratolithic order) comprising nearly all land at the time
- Pangæa Ultima (~250 – ~400 million years from now)
- Pangæa (~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 Ur was smaller than Australia is today)
