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Arctida
Arctica or Arctida was an ancient continent which formed approximately 2.565 billion years ago in the Neoarchean era. It was made of Archaean cratons, including the Siberian Craton, with its Anabar/Aldan shields in Siberia, and the Slave, Wyoming, Superior, and North Atlantic cratons in North America. Arctica was named by because the Arctic Ocean formed by the separation of the North American and Siberian cratons. Russian geologists writing in English call the continent "Arctida" since it was given that name in 1987, alternatively the Hyperborean craton, in reference to the hyperboreans in Greek mythology. Nikolay Shatsky () was the first to assume that the crust in the Arctic region was of continental origin. Shatsky, however, was a "fixist" and, erroneously, explained the presence of Precambrian and Paleozoic metamorphic rocks on the New Siberian, Wrangel, and De long Islands with subduction. "Mobilists", on the other hand, also erroneously, proposed that North Amer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleocontinent
A paleocontinent or palaeocontinent is a distinct area of continental crust that existed as a major landmass in the geological past. There have been many different landmasses throughout Earth's time. They range in sizes, some are just a collection of small microcontinents while others are large conglomerates of crust. As time progresses and sea levels rise and fall more crust can be exposed making way for larger landmasses. The continents of the past shaped the evolution of organisms on Earth and contributed to the climate of the globe as well. As landmasses break apart, species are separated and those that were once the same now have evolved to their new climate. The constant movement of these landmasses greatly determines the distribution of organisms on Earth's surface. This is evident with how similar fossils are found on completely separate continents. Also, as continents move, mountain building events (orogenies) occur, causing a shift in the global climate as new rock is expo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greek Mythology
A major branch of classical mythology, Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and a genre of Ancient Greek folklore. These stories concern the Cosmogony, origin and Cosmology#Metaphysical cosmology, nature of the world, the lives and activities of List of Greek mythological figures, deities, Greek hero cult, heroes, and List of Greek mythological creatures, mythological creatures, and the origins and significance of the ancient Greeks' own cult (religious practice), cult and ritual practices. Modern scholars study the myths to shed light on the religious and political institutions of ancient Greece, and to better understand the nature of myth-making itself. The Greek myths were initially propagated in an oral tradition, oral-poetic tradition most likely by Minoan civilization, Minoan and Mycenaean Greece, Mycenaean singers starting in the 18th century BC; eventually the myths of the heroes of the Trojan War and its after ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rodinia
Rodinia (from the Russian родина, ''rodina'', meaning "motherland, birthplace") was a Mesoproterozoic and Neoproterozoic supercontinent that assembled 1.26–0.90 billion years ago and broke up 750–633 million years ago. were probably the first to recognise a Precambrian supercontinent, which they named 'Pangaea I'. It was renamed 'Rodinia' by who also were the first to produce a reconstruction and propose a temporal framework for the supercontinent. Rodinia formed at c. 1.23 Ga by accretion and collision of fragments produced by breakup of an older supercontinent, Columbia, assembled by global-scale 2.0–1.8 Ga collisional events.; Rodinia broke up in the Neoproterozoic with its continental fragments reassembled to form Pannotia 633–573 million years ago. In contrast with Pannotia, little is known yet about the exact configuration and geodynamic history of Rodinia. Paleomagnetic evidence provides some clues to the paleolatitude of individual pieces of the Ea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nena (supercontinent)
Nena, an acronym for Northern Europe–North America, was the Early Proterozoic amalgamation of Baltica and Laurentia into a single "cratonic landmass", a name first proposed in 1990. Since then several similar Proterozoic supercontinents have been proposed, including Nuna and Arctica, that include other Archaean cratons, such as Siberia and East Antarctica. In the original concept Nena formed in the Penokean, Makkovikan, Ketilidian, and Svecofennian orogenies. However, because Nena excludes several known Archaean cratons, including those in India and Australia, it is strictly speaking not a supercontinent. Although Nena and Nuna share many similarities, Nena accounted for a larger landmass than Nuna. This extended landmass included the Angara, Antarctica, Baltica, Laurentia Laurentia or the North American Craton is a large continental craton that forms the ancient geological core of North America. Many times in its past, Laurentia has been a separate continent, as it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baltica
Baltica is a paleocontinent that formed in the Paleoproterozoic and now constitutes northwestern Eurasia, or Europe north of the Trans-European Suture Zone and west of the Ural Mountains. The thick core of Baltica, the East European Craton, is more than three billion years old and formed part of the Rodinia supercontinent at 1 . Tectonic history Baltica formed at 2.0–1.7 Ga by the collision of three Archaean-Proterozoic continental blocks: Fennoscandia (including the exposed Baltic Shield), Sarmatia (Ukrainian Shield and Voronezh Massif), and Volgo-Uralia (covered by younger deposits). Sarmatia and Volgo-Uralia formed a proto-craton (sometimes called "Proto-Baltica") at c. 2.0 Ga which collided with Fennoscandia c. 1.8–1.7 Ga. The sutures between these three blocks were reactivated during the Mesoproterozoic and Neoproterozoic. 750–600 million years ago, Baltica and Laurentia rotated clockwise together and drifted away from the Equator towa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
West African Craton
The West African Craton (WAC) is one of the five cratons of the Precambrian basement rock of Africa that make up the African Plate, the others being the Kalahari craton, Congo craton, Saharan Metacraton and Tanzania Craton.Jessell M.W., Liégeois J-P. (2015). "100 years of research on the West African Craton". ''Journal of African Earth Sciences''. 112(B): 377– 381. Cratons themselves are tectonically inactive, but can occur near active margins,Ennih N. & Liégeois J-P. (2008). ''The Boundaries of the West African Craton''. Geological Society, London, Special Publications. 297: 1–17. with the WAC extending across 14 countries in Western Africa, coming together in the late Precambrian and early Palaeozoic eras to form the African continent. It consists of two Archean centers juxtaposed against multiple Paleoproterozoic domains made of greenstone belts, sedimentary basins, regional granitoid-tonalite-trondhjemite-granodiorite, tonalite-trondhjemite-granodiorite (TTG) plutons, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atlantica
Atlantica ( gr, Ατλαντικα; ''Atlantika'') is an ancient continent that formed during the Proterozoic about (two billion years ago, Ga) from various 2 Ga cratons located in what are now West Africa and eastern South America. The name, introduced by , was chosen because the parts of the ancient continent are now located on opposite sides of the South Atlantic Ocean. Formation Atlantica formed simultaneously with Nena at about 1.9 Ga from Archaean cratons, including Amazonia in present-day South America, and the Congo, West Africa and North Africa Cratons in Africa. Breakup Atlantica separated from Nena between 1.6–1.4 Ga when Columbia — a supercontinent composed of Ur, Nena, and Atlantica — fragmented. Atlantica and continents Nena and Ur and some minor plates formed the supercontinent Rodinia about 1 Ga ago. Between 1–0.5 Ga Rodinia split into three new continents: Laurasia and East and West Gondwana; Atlantica became the nucleus of West Gond ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canadian Shield
The Canadian Shield (french: Bouclier canadien ), also called the Laurentian Plateau, is a geologic shield, a large area of exposed Precambrian igneous and high-grade metamorphic rocks. It forms the North American Craton (or Laurentia), the ancient geologic core of the North American continent. Glaciation has left the area with only a thin layer of soil, through which exposures of igneous bedrock resulting from its long volcanic history are frequently visible. As a deep, common, joined bedrock region in eastern and central Canada, the Shield stretches north from the Great Lakes to the Arctic Ocean, covering over half of Canada and most of Greenland; it also extends south into the northern reaches of the United States. Geographical extent The Canadian Shield is a physiographic division comprising four smaller physiographic provinces: the Laurentian Upland, Kazan Region, Davis and James. The shield extends into the United States as the Adirondack Mountains (connected by the Fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
East Antarctica
East Antarctica, also called Greater Antarctica, constitutes the majority (two-thirds) of the Antarctic continent, lying on the Indian Ocean side of the continent, separated from West Antarctica by the Transantarctic Mountains. It lies almost entirely within the Eastern Hemisphere and its name has been accepted for more than a century. It is generally higher than West Antarctica and includes the Gamburtsev Mountain Range in the center. The geographic South Pole is located within East Antarctica. Apart from small areas of the coast, East Antarctica is permanently covered by ice and it has relatively low biodiversity, with only a small number of species of terrestrial plants, animals, algae, and lichens. The coasts are the breeding ground for various seabirds and penguins, and the leopard seal, Weddell seal, elephant seal, crabeater seal and Ross seal breed on the surrounding pack ice in summer. Location and description Almost completely covered in thick, permanent ice, East A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gondwana
Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages of break-up, involving the separation of Antarctica from South America (forming the Drake Passage) and Australia, occurred during the Paleogene. Gondwana was not considered a supercontinent by the earliest definition, since the landmasses of Baltica, Laurentia, and Siberia were separated from it. To differentiate it from the Indian region of the same name (see ), it is also commonly called Gondwanaland. Gondwana was formed by the accretion of several cratons. Eventually, Gondwana became the largest piece of continental crust of the Palaeozoic Era, covering an area of about , about one-fifth of the Earth's surface. During the Carboniferous Period, it merged with Laurasia to form a larger supercontinent called Pangaea. Gondwana (and Pan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gigaannum
A year or annus is the orbital period of a planetary body, for example, the Earth, moving in its orbit around the Sun. Due to the Earth's axial tilt, the course of a year sees the passing of the seasons, marked by change in weather, the hours of daylight, and, consequently, vegetation and soil fertility. In temperate and subpolar regions around the planet, four seasons are generally recognized: spring, summer, autumn and winter. In tropical and subtropical regions, several geographical sectors do not present defined seasons; but in the seasonal tropics, the annual wet and dry seasons are recognized and tracked. A calendar year is an approximation of the number of days of the Earth's orbital period, as counted in a given calendar. The Gregorian calendar, or modern calendar, presents its calendar year to be either a common year of 365 days or a leap year of 366 days, as do the Julian calendars. For the Gregorian calendar, the average length of the calendar year (the mean y ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ur (continent)
Ur is a hypothetical supercontinent that formed in the Archean (3.1 billion). In a reconstruction by Rodgers, Ur is half a billion years older than Arctica and, in the early period of its existence, it was probably the only continent on Earth, and as such can be considered a supercontinent, though it was probably smaller than present-day Australia. In more recent works geologists often refer to both Ur and other proposed Archaean continental assemblages as supercratons. Ur can, nevertheless, be half a billion years younger than Vaalbara, but the concepts of these two early cratonic assemblages are incompatible. Incompatible reconstructions About 1,300–1,071 Mya, Ur joined the continents Nena and Atlantica to form the supercontinent Rodinia. In the reconstruction of , Ur remained the nucleus of East Gondwana until the break-up of Gondwana. In other reconstructions, however, India and East Antarctica did not collide until Rodinia formed 1,071 Mya. Furthermore, in the Early ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
