Most commonly, the term supercontinent is used to refer to a landmass consisting of all the modern continents. Such a landmass is formed or destroyed, 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.
The supercontinent Rodinia broke up roughly 600 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, Pangaea, forming in the late Paleozoic. Pangaea broke up into the northern and southern supercontinents, Laurasia and Gondwana.