There is strong evidence that most of the Earth's continents have been periodically joined together into supercontinents as the movement of the plates brought them together. The most recent of these supercontinents, Pangaea, formed about 270 million years ago and broke up about 200 million years ago.
The geologic record provides evidence of older supercontinents than Pangaea and a so-called "supercontinent cycle" of periodic supercontinent formation and break-up. What ultimately drives the cycle is a subject of scientific debate.
Image: Artwork showing the predicted position of the Earth's continents about 250 million years in the future (credit: Christian Darkin/SPL)
In geology, a supercontinent is the assembly of most or all of the Earth's continental blocks or cratons to form a single large landmass. However, the definition of a supercontinent can be ambiguous. Many tectonicists such as Hoffman (1999) use the term “supercontinent” to mean “a clustering of nearly all continents”. This definition leaves room for interpretation when labeling a continental body and is easier to apply to Precambrian times. Using the first definition provided here, Gondwana (aka Gondwanaland) is not considered a supercontinent, because the landmasses of Baltica, Laurentia and Siberia also existed at the same time but physically separate from each other. The landmass of Pangaea is the collective name describing all of these continental masses when they were in a close proximity to one another. This would classify Pangaea as a supercontinent (Figure 1). According to the definition by Rogers and Santosh (2004), a supercontinent does not exist today (Figure 2). Supercontinents have assembled and dispersed multiple times in the geologic past (Table 1). The positions of continents have been accurately determined back to the early Jurassic. However, beyond 200 Ma, continental positions are much less certain.
Table 1- Supercontinents through geologic history using a general definition.