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To separate supercontinents from other groupings, a limit has been proposed in which a continent must include at least about 75% of the continental crust then in existence in order to qualify as a supercontinent. [5] Moving under the forces of plate tectonics, supercontinents have assembled and dispersed multiple times in the geologic past.
The degree of certainty to which the identified landmasses can be regarded as independent entities reduces as geologists look further back in time. The list includes cratons, supercratons, microcontinents, continents and supercontinents. For the Archean to Paleoproterozoic cores of most of the continents see also list of shields and cratons.
Columbia, also known as Nuna or Hudsonland, is a hypothetical ancient supercontinent. It was first proposed by John J.W. Rogers and M. Santosh in 2002 [1] and is thought to have existed approximately (Ma), in the Paleoproterozoic era. The assembly of the supercontinent was likely completed during global-scale collisional events from 2,100 to ...
Map of Pangaea with modern continental outlines. The supercontinent cycle is the quasi-periodic aggregation and dispersal of Earth's continental crust.There are varying opinions as to whether the amount of continental crust is increasing, decreasing, or staying about the same, but it is agreed that the Earth's crust is constantly being reconfigured.
Gondwana (/ ɡ ɒ n d ˈ w ɑː n ə /) [1] was a large landmass, sometimes referred to as a supercontinent.The remnants of Gondwana make up around two-thirds of today's continental area, including South America, Africa, Antarctica, Australia, Zealandia, Arabia, and the Indian Subcontinent.
Unlike later supercontinents, Rodinia was entirely barren. It existed before complex life colonized on dry land. Based on sedimentary rock analysis, Rodinia's formation happened when the ozone layer was not as extensive as it is now. Ultraviolet light discouraged organisms from inhabiting its interior.
Ur is a hypothetical supercontinent that formed in the Archean eon around 3.1 billion years ago (Ga). In a reconstruction by Rogers, Ur is half a billion years older than Arctica and, in the early period of its existence, probably the only continent on Earth, making it a supercontinent despite probably being smaller than present-day Australia.
Vaalbara thus remained stable for 1–0.4 Ga and hence had a life span similar to that of later supercontinents such as Gondwana and Rodinia. [10] Some palaeomagnetic reconstructions suggest a Palaeoarchaean proto-Vaalbara is possible, although the existence of this 3.6–3.2 Ga continent cannot be proven. [12]