Vaalbara

Vaalbara is a hypothetical Archean supercontinent consisting of the Kaapvaal craton (in present-day eastern South Africa) and the Pilbara Craton (in present-day north-western Western Australia). E. S. Cheney derived the name from the last four letters of each craton's name. The two cratons consist of continental crust dating from 3.6 to 2.7 Ga; this timing would make Vaalbara one of Earth's earliest supercontinents.

==Existence and lifespan== There has been some debate as to when and even if Vaalbara existed. An Archaean–Palaeoproterozoic (2.8–2.1 Ga) link between South Africa and Western Australia was first proposed by Alan Button in 1976. He found a wide range of similarities between the Transvaal Basin in South Africa and the Hamersley Basin in Australia. Button, however, placed Madagascar between Africa and Australia and concluded that Gondwana must have had a long stable tectonic history. Similarly, in the reconstruction of Rogers 1993, 1996 the oldest continent is Ur. In Rogers' reconstructions, however, Kaapvaal and Pilbara are placed far apart already in their Gondwana configuration, a reconstruction contradicted by later orogenic events and incompatible with the Vaalbara hypothesis.