Ur (continent)

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Ur is a hypothetical first supercontinent that is believed to have formed 3 billion years ago, in the early Archean , near the equator. It is believed to be smaller than what is now Australia.


The name Ur was suggested by John JW Rogers in 1993 . The name is derived from the German prefix ur- for originally, old, but also alludes to the Mesopotamian city Ur , one of the oldest cities in the world, and is intended to indicate that it is the first and oldest supercontinent. Although Ur was relatively small and could not compete in size with the later supercontinents, the term supercontinent applies to the extent that 3 billion years ago a contiguous land mass of all or at least almost all of the continental cores on earth that existed at that time was formed.


Ur consisted of four larger cratons , the Western Dharwar and the Singhbhum craton of India, the Kaapvaal craton of South Africa and the Pilbara craton of Australia. In addition there are probably three smaller cratons in the Antarctic and possibly two other smaller cratons in India, the Eastern Dharwar craton and the Bhandara craton . It is conceivable that Ur formed from several smaller continents. Nelson et al. (1999) suggest, based on the very similar geological history, that the Kaapvaal and Pilbara cratons once formed a small continent they called Vaalbara .

Ur as a continent

Ur was increased by 2500 mya due to the accretion of the Zimbabwe craton to the Kaapvaal craton along the Limpopo Belt and the accretion of the Yilgarn craton to the Pilbara craton. This continent is called extended Ur , translated as "greater Ur". This continent, enlarged by further crustal parts, joined according to this plate tectonic model with Eastern Antarctica, Nena and Atlantica 1.1 to 1 billion years ago to form the global supercontinent Rodinia . He formed the core of the later Gondwana . Today its crustal parts are distributed over the continents Africa, Antarctica and Australia as well as the subcontinent India.

Older crust fragments

Since the discovery of the possibly up to 4.3 billion year old Nuvvuagittuq greenstone belt from the eastern Canadian shield , the 4030 mya old Acasta gneisses and similar old splinters on various continents, it can be assumed that mainland islands already existed in the Hadean . Such rock finds were made in Montana , Wyoming , in the Enderby country of Antarctica , on the Sino - Korean border, in Goa , around the Greenland capital Nuuk , in Brazil and Africa .



  • John J. W. Rogers: India and Ur. Journal of the Geological Society of India, 42: 217-22, Bangalore 1993 ISSN  0016-7622
  • John J. W. Rogers and M. Santosh: Supercontinents in Earth History. Gondwana Research , 6 (3): 357-368, Osaka 2003 ISSN  1342-937X .