Vaalbara

Vaalbara was an Archean supercontinent that consisted of the Kaapvaal craton, today located in eastern South Africa, and the Pilbara craton, today found in north-western Western Australia. Vaalbara was named by Cheney 1996 who derived the name from the last four letters of each craton's name. The two cratons are made of 3.6±2.7 Ga-old crust, making Vaalbara the oldest supercontinent on Earth.

There has been some debate when and whether Vaalbara existed.

An Archaean-Palaeoproterozoic (2.8–2.1 Ga) link between South Africa and Western Australia was first proposed by Button 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.

Cheney 1996, nevertheless, found a three-fold stratigraphic similarity and proposed that the two cratons once formed a continent which he named Vaalbara. This model is supported by the palaeomagnetic data of Zegers, de Wit & White 1998. Reconstructions of the palaeolatitudes of the two cratons at 2.78–2.77 Ga are ambiguous however. In the reconstruction of Wingate 1998 they fail to overlap, but they do in more recent reconstructions, for example Strik et al. 2003.

Other scientists dispute the existence of Vaalbara and explain similarities between the two cratons as the product of global processes. They point to, for example, thick volcanic deposits on other cratons such as Amazonia, São Francisco, and Karnataka.

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