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[[Image:Pangaea continents.png|right|250px|thumb|Map of Pangaea]] |
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'''Pangaea''', '''Pangæa''' or '''Pangea''' ({{IPAEng|pænˈdʒiːə}}<ref>OED</ref>, from παν, pan, meaning entire, and Γαῖα, Gaea, meaning Earth in [[Ancient Greek]]) was the [[supercontinent]] that existed during the [[Paleozoic]] and [[Mesozoic]] eras about 250 million years ago, before the component [[continent]]s were separated into their current configuration <ref>Plate Tectonics and Crustal Evolution, Third Ed., 1989, by Kent C. Condie, Pergamon Press</ref>. |
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The name was first used by the [[German people|German]] originator of the [[continental drift]] theory, [[Alfred Wegener]], in the 1920 edition of his book ''The Origin of Continents and Oceans (Die Entstehung der Kontinente und Ozeane)'', in which a postulated supercontinent Pangaea played a key role. |
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== Configuration of Pangaea == |
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[[Image:Pangaea (230 million years ago).png|275px|thumb|left|Physical map of the supercontinent Pangaea (~230 million years ago)]] |
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[[Paleogeography|Paleogeographic]] reconstructions show Pangaea as a roughly C-shaped landmass that was spread across the [[equator]]. The [[body of water]] that was enclosed within the resulting crescent has been named the [[Tethys Sea]]. Owing to Pangaea's massive size, the inland regions appear to have been very dry. The large supercontinent would potentially have allowed terrestrial animals to migrate freely. |
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The vast ocean that surrounded the [[supercontinent]] of Pangaea has been named [[Panthalassa]], which means "all seas". The break-up of Pangaea began about 160 million years ago (180 [[megaannum|mya]]) in the [[Jurassic]] [[Period (geology)|Period]], first into two supercontinents ([[Gondwana]] to the south and [[Laurasia]] to the north), thereafter into the [[continent]]s we have today. |
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==Formation of Pangaea== |
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[[Rodinia]], which formed 1.3 billion years ago during the [[Proterozoic]], was the supercontinent from which all subsequent continents, sub or super, derived. Rodinia does not preclude the possibility of [[Vaalbara|prior supercontinents]] as the breakup and formation of supercontinents appears to be [[supercontinent cycle|cyclical]] through Earth's 4.6 billion years. |
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[[Gondwana]] followed with several iterations before the formation of Pangaea, which succeeded [[Pannotia]], before the beginning of the [[Paleozoic Era]] (545 Ma) and the [[Phanerozoic Eon]]. |
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The minor supercontinent of [[Proto-Laurasia]] drifted away from Gondwana and moved across the [[Panthalassic Ocean]]. A new ocean was forming between the two continents, the [[Proto-Tethys Ocean]]. Soon, Proto-Laurasia drifted apart itself to create [[Laurentia]], [[Siberia (continent)|Siberia]] and [[Baltica]]. The rifting also spawned two new oceans, the [[Iapetus Ocean|Iapetus]] and [[Khanty Ocean]]s. Baltica remained east of Laurentia, and Siberia sat northeast of Laurentia. |
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In the [[Cambrian]] the independent continent of [[Laurentia]] on what would become [[North America]] sat on the [[equator]], with three bordering oceans: the [[Panthalassic Ocean]] to the north and west, the [[Iapetus Ocean]] to the south and the [[Khanty Ocean]] to the east. In the Earliest [[Ordovician]], the microcontinent of [[Avalonia]], a landmass that would become the northeastern [[United States]], [[Nova Scotia]] and [[England]], broke free from Gondwana and began its journey to [[Laurentia]].<ref>{{cite book| last =Stanley| first = Steven| authorlink = Steven M. Stanley| title = Earth System History| date = 1998| location = USA| pages = 355-359 }}</ref> |
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[[Image:Euramerica en.svg|245px|thumb|right|Euramerica's formation]] |
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[[Image:Appalachian orogeny.jpg|thumb|235px|right|Appalachian orogeny]] |
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[[Baltica]] collided with Laurentia by the end of the Ordovician and northern Avalonia collided with Baltica and Laurentia. Laurentia, Baltica and Avalonia formed to create a minor supercontinent of [[Euramerica]] or Laurussia, closing the Iapetus Ocean, while the [[Rheic Ocean]] expanded in the southern coast of Avalonia. The collision also resulted in the formation of the northern [[Appalachians]]. [[Siberia (continent)|Siberia]] sat near Euramerica, with the [[Khanty Ocean]] between the two continents. While all this was happening, Gondwana drifted slowly towards the South Pole. This was the first step of the formation of Pangaea.<ref>{{cite book| last =Stanley| first = Steven| authorlink = Steven M. Stanley| title = Earth System History| date = 1998| location = USA| pages = 386-392 }}</ref> |
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The second step in the formation of Pangaea was the collision of Gondwana with [[Euramerica]]. By [[Silurian]] time, Baltica had already collided with Laurentia to form Euramerica. [[Avalonia]] hadn't collided with [[Laurentia]] yet, and a seaway between them, a remnant of the [[Iapetus Ocean]], was still shrinking as Avalonia slowly inched towards Laurentia. |
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Meanwhile, [[southern Europe]] fragmented from Gondwana and started to head towards Euramerica across the newly formed [[Rheic Ocean]] and collided with southern [[Baltica]] in the [[Devonian]], though this microcontinent was an underwater plate. The Iapetus Ocean's sister ocean, the Khanty Ocean, was also shrinking as an island arc from Siberia collided with eastern Baltica (now part of Euramerica). Behind this [[island arc]] was a new ocean, the [[Ural Ocean]]. |
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By late Silurian time, [[North China (continent)|North]] and [[South China (continent)|South China]] rifted away from Gondwana and started to head northward across the shrinking Proto-Tethys Ocean, and on its southern end the new [[Paleo-Tethys Ocean]] was opening. In the Devonian Period, Gondwana itself headed towards Euramerica, which caused the Rheic Ocean to shrink. |
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In the Early [[Carboniferous]], northwest [[Africa]] had touched the southeastern coast of [[Euramerica]], creating the southern portion of the [[Appalachian Mountains]], and the [[Meseta Mountains]]. [[South America]] moved northward to southern Euramerica, while the eastern portion of Gondwana ([[India]], [[Antarctica]] and [[Australia]]) headed towards the South Pole from the [[equator]]. |
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North China and South China were on independent continents. The [[Kazakhstania]] microcontinent had collided with [[Siberia (continent)|Siberia]] (Siberia had been a separate continent for millions of years since the deformation of the supercontinent [[Pannotia]]) in the Middle Carboniferous. |
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Western [[Kazakhstania]] collided with [[Baltica]] in the Late Carboniferous, closing the [[Ural Ocean]] between them, and the western Proto-Tethys in them ([[Uralian orogeny]]), causing the formation of the [[Ural Mountains]], and the formation of the supercontinent of Laurasia. This was the last step of the formation of Pangaea. |
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Meanwhile, South America had collided with southern [[Laurentia]], closing the [[Rheic Ocean]], and forming the southernmost part of the [[Appalachians]] and [[Ouachita Mountains]]. By this time, Gondwana was positioned near the South Pole, and glaciers were forming in Antarctica, India, Australia, southern Africa and South America. The [[North China]] block collided with [[Siberia]] by Late Carboniferous time, completely closing the Proto-Tethys Ocean. |
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By Early [[Permian]] time, the [[Cimmerian plate]] rifted away from Gondwana and headed towards Laurasia, with a new ocean forming in its southern end, the [[Tethys Ocean]], and the closure of the [[Paleo-Tethys Ocean]]. Most of the landmasses were all in one. By the [[Triassic]] Period, Pangaea rotated a little, in a southwest direction. The Cimmerian plate was still travelling across the shrinking Paleo-Tethys, until the [[Middle Jurassic]] time. The Paleo-Tethys had closed from west to east, creating the [[Cimmerian Orogeny]]. Pangaea looked like a ''C'', with an ocean inside the ''C'', the new Tethys Ocean. Pangaea had rifted by the Middle Jurassic, and its deformation is explained below. |
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==Evidence of Pangaea's existence== |
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[[Fossil]] evidence for Pangaea includes the presence of similar and identical species on continents that are now great distances apart. For example, fossils of the [[therapsid]] ''[[Lystrosaurus]]'' have been found in [[Gandu]], [[South Africa]], [[India]] and [[Australia]], alongside members of the ''[[Glossopteris]]'' flora, whose distribution would have ranged from the polar circle to the equator if the continents had been in their present position; similarly, the freshwater reptile ''[[Mesosaurus]]'' has only been found in localized regions of the coasts of [[Brazil]] and [[West Africa]].<ref>Benton, M.J. ''Vertebrate Palaeontology''. Third edition (Oxford 2005), 25.</ref> |
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Additional evidence for Pangaea is found in the [[geology]] of adjacent continents, including matching geological trends between the eastern coast of [[South America]] and the western coast of [[Africa]]. |
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The [[polar ice cap]] of the [[Carboniferous]] Period covered the southern end of Pangaea. Glacial deposits, specifically [[till]], of the same age and structure are found on many separate continents which would have been together in the continent of Pangaea.<ref>Barbara W. Murck, Brian J. Skinner, ''Geology Today: Understanding Our Planet, Study Guide'', Wiley, ISBN 978-0-471-32323-5</ref> |
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==Rifting and break-up of Pangaea== |
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[[Image:Pangea animation 03.gif|thumb|240px|Pangaea separation animation]] |
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There were three major phases in the break-up of Pangaea. The first phase began in the [[Early Jurassic|Early]]-[[Middle Jurassic]], when Pangaea created a rift from the Tethys Ocean in the east and the [[Pacific]] in the west. The rifting took place between North America and Africa, and produced multiple failed rifts. The rift resulted in a new ocean, the [[Atlantic Ocean]]. |
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The Atlantic Ocean did not open uniformly; rifting began in the north-central Atlantic. The [[South Atlantic]] did not open until the [[Cretaceous]]. Laurasia started to rotate clockwise and moved northward with North America to the north, and [[Eurasia]] to the south. The clockwise motion of Laurasia also led to the closing of the Tethys Ocean. Meanwhile, on the other side of Africa, new rifts were also forming along the adjacent margins of east Africa, Antarctica and [[Madagascar]] that would lead to the formation of the southwestern [[Indian Ocean]] that would also open up in the Cretaceous. |
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The second major phase in the break-up of Pangaea began in the [[Early Cretaceous]] (150–140 Ma), when the minor supercontinent of Gondwana separated into four multiple continents (Africa, South America, India and Antarctica/Australia). About 200 Ma, the continent of [[Cimmerian Plate|Cimmeria]], as mentioned above (see "[[Pangaea#Formation of Pangaea|Formation of Pangaea]]"), collided with Eurasia. However, a subduction zone was forming, as soon as Cimmeria collided. |
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This subduction zone was called the [[Tethyan Trench]]. This trench might have subducted what is called the Tethyan [[mid-ocean ridge]], a ridge responsible for the Tethys Ocean's expansion. It probably caused Africa, India and Australia to move northward. In the Early Cretaceous, [[Atlantica]], today's South America and Africa, finally separated from eastern Gondwana (Antarctica, India and Australia), causing the opening of a "South Indian Ocean". In the Middle Cretaceous, Gondwana fragmented to open up the South Atlantic Ocean as South America started to move westward away from Africa. The South Atlantic did not develop uniformly; rather, it rifted from south to north. |
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Also, at the same time, [[Madagascar]] and India began to separate from Antarctica and moved northward, opening up the Indian Ocean. Madagascar and India separated from each other 100–90 Ma in the Late Cretaceous. India continued to move northward toward Eurasia at 15 centimeters (6 in) per year (a plate tectonic record), closing the Tethys Ocean, while Madagascar stopped and became locked to the [[African Plate]]. [[New Zealand]], [[New Caledonia]] and the rest of [[Zealandia (continent)|Zealandia]] began to separate from Australia, moving eastward towards the [[Pacific]] and opening the [[Coral Sea]] and [[Tasman Sea]]. |
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The third major and final phase of the break-up of Pangaea occurred in the early [[Cenozoic]] ([[Paleocene]] to [[Oligocene]]). North America/[[Greenland]] broke free from Eurasia, opening the [[Norwegian Sea]] about 60–55 Ma. The Atlantic and Indian Oceans continued to expand, closing the Tethys Ocean. |
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Meanwhile, Australia split from Antarctica and moved rapidly northward, just as India did more than 40 million years earlier, and is currently on a collision course with [[eastern Asia]]. Both Australia and India are currently moving in a northeastern direction at 5–6 centimeters (2–3 in) per year. Antarctica has been near or at the South Pole since the formation of Pangaea about 280 Ma. India started to collide with [[Asia]] beginning about 35 Ma, forming the [[Himalayan orogeny]], and also finally closing the [[Tethys Seaway]]; this collision continues today. The African Plate started to change directions, from west to northwest toward [[Europe]], and South America began to move in a northward direction, separating it from Antarctica and allowing complete oceanic circulation around Antarctica for the first time, causing a rapid cooling of the continent and allowing [[glacier]]s to form. Other major events took place during the [[Cenozoic]], including the opening of the [[Gulf of California]], the uplift of the [[Alps]], and the opening of the [[Sea of Japan]]. The break-up of Pangaea continues today in the [[Great Rift Valley]]; ongoing collisions may indicate the incipient creation of a new [[supercontinent]]. |
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In around 250 million years, all of the world's continents may be merged together in one landmass again as [[Amasia (continent)|Amasia]] or [[Pangaea Ultima]]. |
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==See also== |
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* [[List of supercontinents]] |
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* [[History of Earth]] |
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* [[Supercontinent cycle]] |
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==References== |
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{{reflist}} |
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== External links == |
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{{commons|Pangea|Pangaea}} |
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{{Wiktionary|Pangaea}} |
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* [http://pubs.usgs.gov/publications/text/historical.html USGS Overview] |
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* In honor of [[Alfred Wegener]], at the [[Alfred Wegener Institute for Polar and Marine Research]] (AWI) an information system for georeferenced data from earth system research is named [http://www.pangaea.de/ "pangaea |
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* [http://www.tectonic-forces.org An explanation of tectonic forces] |
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*[http://www.foxnews.com/story/0,2933,248979,00.html Europe's First Stegosaurus Boosts Pangaea Theory] |
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* [http://www.scotese.com/newpage8.htm Map of Triassic Pangaea at Paleomaps] |
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{{Continents of the world}} |
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[[Category:Historical continents]] |
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[[Category:Carboniferous]] |
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[[Category:Permian]] |
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[[Category:Triassic]] |
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[[Category:Jurassic]] |
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[[Category:Plate tectonics]] |
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[[Category:Supercontinents]] |
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[[ar:بنجيا]] |
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[[ast:Panxea]] |
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[[br:Pangea]] |
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[[bg:Пангея]] |
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[[ca:Pangea]] |
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[[ceb:Pangaea]] |
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[[cs:Pangea]] |
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[[cy:Pangaea]] |
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[[da:Pangæa]] |
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[[de:Pangaea]] |
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[[dv:ޕަންގިއާ]] |
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[[et:Pangaea]] |
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[[el:Παγγαία]] |
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[[es:Pangea]] |
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[[eo:Pangeo]] |
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[[eu:Pangea]] |
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[[fa:پانجهآ]] |
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[[fr:Pangée (continent)]] |
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[[gd:Pangaea]] |
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[[gl:Panxea]] |
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[[ko:판게아]] |
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[[hr:Pangea]] |
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[[id:Pangea]] |
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[[it:Pangea]] |
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[[he:פנגיאה]] |
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[[ka:პანგეა]] |
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[[ht:Panje]] |
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[[la:Pangaea]] |
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[[lb:Pangäa]] |
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[[lt:Pangėja]] |
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[[hu:Pangea]] |
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[[ml:പാന്ജിയ]] |
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[[mt:Pangea]] |
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[[mr:पँजिआ]] |
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[[nl:Pangea]] |
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[[ja:パンゲア大陸]] |
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[[no:Pangea]] |
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[[nn:Pangea]] |
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[[nov:Pangea]] |
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[[pl:Pangea]] |
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[[pt:Pangéia]] |
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[[ru:Пангея]] |
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[[scn:Pangea]] |
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[[simple:Pangaea]] |
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[[sk:Pangea]] |
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[[sl:Pangea]] |
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[[sr:Пангеа]] |
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[[fi:Pangea]] |
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[[sv:Pangea]] |
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[[tl:Pangaea]] |
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[[ta:ஒருநிலக் கொள்கை]] |
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[[th:มหาทวีปแพนเจีย]] |
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[[vi:Pangaea]] |
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[[tr:Pangea]] |
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[[uk:Пангея]] |
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[[wa:Pandjêye]] |
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[[zh:盤古大陸]] |
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