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 450 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:
- Vaalbara (~3.6 billion years ago)
- Ur (~3.1 billion years ago)
- Kenorland (~2.6 billion years ago)
- Columbia, also called Nuna (~1.8 to 1.5 billion years ago)
- Rodinia (~1.1 billion years to ~750 million years ago)
- Pannotia, also called Vendian (~600 million years to ~540 million years ago)
- Oldredia (~418–~380 million years ago)
- Euramerica (~300 million years ago)
- Pangaea (~300 to ~200 million years ago)
- Laurasia (~510 to ~200 million years ago)
- Gondwana (~510 to ~180 million years ago)