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It is believed that between 3.3 and 3.6 billion years ago land formed on the Earth in a single supercontinent, we now call Vaalbara. According to radiometric data of the encompassing cratons that comprised Vaalbara, we know that it existed at 3.3 billion years ago (3.3 Ga) and possibly even as far back as 3.6 Ga. Evidence includes geochronological and palaeomagnetic studies between the two Archaean cratons (protocontinents) called the Kaapvaal craton (the Kaapvaal province of South Africa) and the Pilbara craton (the Pilbara province of Western Australia). Another piece of evidence is the structural sequence similarities of the greenstone belts and gneiss belts of these two cratons. These same Archaean greenstone belts are now spread out across the margins of the Superior craton of Canada and are also spread out across the cratons of the former Gondwana and Laurasia continents. The subsequent drift paths of the Kaapvaal and Pilbara cratons after 2.8 Ga gives further evidence that they were once connected.

It is not certain when Vaalbara began to break up, but geochronological and palaeomagnetic evidence show that the two cratons had a rotational 30 degree latitudinal separation at 2.78 to 2.77 Ga, implying that they were no longer contiguous after ~2.8 Ga.


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Page last modified on December 09, 2006, at 07:38 PM