Лаврентия (древний материк). Древний материк лаврентия

Лаврентия (древний материк) - это... Что такое Лаврентия (древний материк)?

Лаврентия — континент, существовавший в палеозойскую эру в восточной и центральной Канаде, имя, данное североамериканскому континентальному щиту.

См. также

Ссылки

• Древние континенты
• Суперконтиненты
• Мезозой

Wikimedia Foundation. 2010.

• Лаврентин из Ареццо
• Лаврентьев, Андрей Николаевич

Смотреть что такое "Лаврентия (древний материк)" в других словарях:

• Северная Америка — на карте полушария Северная Америка (англ. North America, фр.  …   Википедия

• Континент — У этого термина существуют и другие значения, см. Континент (значения). Континентальные модели Конти …   Википедия

• Канада — гос во в Сев. Америке. На языке одного из племен индейцев ирокезов каната группа хижин, селение . Франц. колонисты, появившиеся на территории совр. Канады в начале XVII в., восприняли это слово как название деревни, которое затем распространили и …   Географическая энциклопедия

• Северная Америка —         материк в Зап. полушарии.          Oбщие сведения. Площадь C. A. 20,36 млн. км2, вместе c o вами 24,25 млн. км2 (крупные o ва Гренландия, Kанадский Aрктич. архипелаг, Bест Индия, Aлеутские, архипелаг Aлександра). Hac. 395 млн. чел. (cep.… …   Геологическая энциклопедия

• КАНАДА. ПРИРОДА — Границы. Материковая часть Канады омывается на востоке Атлантическим океаном, на севере Северным Ледовитым океаном, на западе Тихим океаном; на суше она граничит с Аляской на западе и с основной территорией США на юге. Граница Канады с Аляской… …   Энциклопедия Кольера

• Лавруссия — (Еврамерика)  палеозойский суперконтинент, который образовался в результате коллизии Северо Американской (древний континент Лаврентия) и Восточно Европейской (древний континент Балтика) платформ во время каледонского орогенеза. Известны… …   Википедия

• ОКЕАН — водная оболочка, покрывающая большую часть земной поверхности (четыре пятых в Южном полушарии и более трех пятых в Северном). Лишь местами земная кора вздымается над поверхностью океана, образуя континенты, острова, атоллы и т.д. Хотя Мировой… …   Энциклопедия Кольера

• МИРОВОЙ ОКЕАН — водная оболочка, покрывающая большую часть земной поверхности (четыре пятых в Южном полушарии и более трех пятых в Северном). Лишь местами земная кора вздымается над поверхностью океана, образуя континенты, острова, атоллы и т.д. Хотя Мировой… …   Энциклопедия Кольера

• Мировой океан — см. океан, Мирового океана ресурсы. География. Современная иллюстрированная энциклопедия. М.: Росмэн. Под редакцией проф. А. П. Горкина. 2006. Мировой океан …   Географическая энциклопедия

• океан — (Мировой океан), непрерывная водная оболочка Земли, окружающая материки и острова и обладающая общностью солевого состава. Составляет большую часть гидросферы (96 %) и покрывает более 70 % площади планеты. Океан находится в непрерывном… …   Географическая энциклопедия

dic.academic.ru

Лаврентия (древний материк) Википедия

Лаврентия — континент, существовавший в палеозойскую эру в восточной и центральной Канаде. Начал формирование 540 млн. л. назад при распаде Паннотии и 335 млн. л. назад объединился с другими континентами в Пангею.

Название континенту дало Лаврентийское плато (Канадский щит), которое в свою очередь так названо по реке Святого Лаврентия.

См. также[ | код]

• Суперконтинент
• Тектоника плит
• Лавразиотерии

Ссылки[ | код]

• United Plates of America (англ.). The Dynamic Earth. National Museum of Natural History. Проверено 1 февраля 2017. Архивировано 6 марта 2005 года.

Континенты

ru-wiki.ru

Лаврентия (древний материк) — Википедия

Лаврентия — континент, существовавший в палеозойскую эру в восточной и центральной Канаде. Начал формирование 540 млн. л. назад при распаде Паннотии и 335 млн. л. назад объединился с другими континентами в Пангею.

Название континенту дало Лаврентийское плато (Канадский щит), которое в свою очередь так названо по реке Святого Лаврентия.

См. также

• Суперконтинент
• Тектоника плит
• Лавразиотерии

Ссылки

• United Plates of America (англ.). The Dynamic Earth. National Museum of Natural History. Проверено 1 февраля 2017. Архивировано 6 марта 2005 года.

Континенты

wikipedia.green

Лаврентия (древний материк) - WikiVisually

1. Континент – A continent is one of several very large landmasses on Earth. Generally identified by convention rather than any strict criteria, up to seven regions are regarded as continents. Ordered from largest in size to smallest, they are, Asia, Africa, North America, South America, Antarctica, Europe, in geology, areas of continental crust include regions covered with water. Islands are frequently grouped with a continent to divide all the worlds land into geopolitical regions. Under this scheme, most of the countries and territories in the Pacific Ocean are grouped together with the continent of Australia to form a geopolitical region called Oceania. By convention, continents are understood to be large, continuous, discrete masses of land, many of the seven most commonly recognized continents identified by convention are not discrete landmasses separated completely by water. Earths major landmasses all have coasts on a single, continuous World Ocean, the most restricted meaning of continent is that of a continuous area of land or mainland, with the coastline and any land boundaries forming the edge of the continent. From this perspective the edge of the shelf is the true edge of the continent. In this sense the islands of Great Britain and Ireland are part of Europe, while Australia, as a cultural construct, the concept of a continent may go beyond the continental shelf to include oceanic islands and continental fragments. In this way, Iceland is considered part of Europe and Madagascar part of Africa, extrapolating the concept to its extreme, some geographers group the Australasian continental plate with other islands in the Pacific into one continent called Oceania. This divides the land surface of Earth into continents or quasi-continents. The ideal criterion that each continent be a discrete landmass is commonly relaxed due to historical conventions, of the seven most globally recognized continents, only Antarctica and Australia are completely separated from other continents by ocean. Several continents are defined not as absolutely distinct bodies but as more or less discrete masses of land, Asia and Africa are joined by the Isthmus of Suez, and North and South America by the Isthmus of Panama. In both cases, there is no separation of these landmasses by water. Both these isthmuses are very narrow compared to the bulk off the landmasses they unite, North America and South America are treated as separate continents in the seven-continent model. However, they may also be viewed as a continent known as America or the Americas. This viewpoint was common in the United States until World War II and this remains the more common vision in Latin American countries, Spain, Portugal, France, Italy and Greece, where they are taught as a single continent. The criterion of a landmass is completely disregarded if the continuous landmass of Eurasia is classified as two separate continents, Europe and Asia

2. Палеозой – The Paleozoic Era is the earliest of three geologic eras of the Phanerozoic Eon, from 541 to 252.17 million years ago. It is the longest of the Phanerozoic eras, and is subdivided into six periods, the Cambrian, Ordovician, Silurian, Devonian, Carboniferous. The Paleozoic comes after the Neoproterozoic era of the Proterozoic and is followed by the Mesozoic, the Paleozoic was a time of dramatic geological, climatic, and evolutionary change. The Cambrian witnessed the most rapid and widespread diversification of life in Earths history, known as the Cambrian explosion, fish, arthropods, amphibians, anapsids, synapsids, euryapsids and diapsids all evolved during the Paleozoic. Life began in the ocean but eventually transitioned onto land, and by the late Paleozoic, Great forests of primitive plants covered the continents, many of which formed the coal beds of Europe and eastern North America. Towards the end of the era, large, sophisticated diapsids and synapsids were dominant, the Paleozoic Era ended with the largest extinction event in the history of Earth, the Permian–Triassic extinction event. The effects of this catastrophe were so devastating that it took life on land 30 million years into the Mesozoic Era to recover, recovery of life in the sea may have been much faster. The Paleozoic era began and ended with supercontinents and in between were the rise of mountains along the margins, and flooding and draining of shallow seas between. At its start, the supercontinent Pannotia broke up, paleoclimatic studies and evidence of glaciers indicate that central Africa was most likely in the polar regions during the early Paleozoic. During the early Paleozoic, the huge continent Gondwana formed or was forming, by mid-Paleozoic, the collision of North America and Europe produced the Acadian-Caledonian uplifts, and a subduction plate uplifted eastern Australia. There are six periods in the Paleozoic Era, Cambrian, Ordovician, Silurian, Devonian, Carboniferous, the Cambrian spans from 541 million years to 485 million years and is the first period of the Paleozoic era of the Phanerozoic. The Cambrian marked a boom in evolution in an event known as the Cambrian explosion in which the largest number of creatures evolved in any period of the history of the Earth. Creatures like algae evolved, but the most ubiquitous of that period were the armored arthropods, almost all marine phyla evolved in this period. During this time, the supercontinent Pannotia begins to break up, the Ordovician spanned from 485 million years to 443 million years ago. The Ordovician is a time in Earths history in many of the biological classes still prevalent today evolved, such as primitive fish, cephalopods. The most common forms of life, however, were trilobites, snails, more importantly, the first arthropods went ashore to colonize the empty continent of Gondwana. By the end of the Ordovican, Gondwana was at the pole, early North America had collided with Europe. Glaciation of Africa resulted in a drop in sea level

3. Канада – Canada is a country in the northern half of North America. Canadas border with the United States is the worlds longest binational land border, the majority of the country has a cold or severely cold winter climate, but southerly areas are warm in summer. Canada is sparsely populated, the majority of its territory being dominated by forest and tundra. It is highly urbanized with 82 per cent of the 35.15 million people concentrated in large and medium-sized cities, One third of the population lives in the three largest cities, Toronto, Montreal and Vancouver. Its capital is Ottawa, and other urban areas include Calgary, Edmonton, Quebec City, Winnipeg. Various aboriginal peoples had inhabited what is now Canada for thousands of years prior to European colonization. Pursuant to the British North America Act, on July 1,1867, the colonies of Canada, New Brunswick and this began an accretion of provinces and territories to the mostly self-governing Dominion to the present ten provinces and three territories forming modern Canada. With the Constitution Act 1982, Canada took over authority, removing the last remaining ties of legal dependence on the Parliament of the United Kingdom. Canada is a parliamentary democracy and a constitutional monarchy, with Queen Elizabeth II being the head of state. The country is officially bilingual at the federal level and it is one of the worlds most ethnically diverse and multicultural nations, the product of large-scale immigration from many other countries. Its advanced economy is the eleventh largest in the world, relying chiefly upon its abundant natural resources, Canadas long and complex relationship with the United States has had a significant impact on its economy and culture. Canada is a country and has the tenth highest nominal per capita income globally as well as the ninth highest ranking in the Human Development Index. It ranks among the highest in international measurements of government transparency, civil liberties, quality of life, economic freedom, Canada is an influential nation in the world, primarily due to its inclusive values, years of prosperity and stability, stable economy, and efficient military. While a variety of theories have been postulated for the origins of Canada. In 1535, indigenous inhabitants of the present-day Quebec City region used the word to direct French explorer Jacques Cartier to the village of Stadacona, from the 16th to the early 18th century Canada referred to the part of New France that lay along the St. Lawrence River. In 1791, the area became two British colonies called Upper Canada and Lower Canada collectively named The Canadas, until their union as the British Province of Canada in 1841. Upon Confederation in 1867, Canada was adopted as the name for the new country at the London Conference. The transition away from the use of Dominion was formally reflected in 1982 with the passage of the Canada Act, later that year, the name of national holiday was changed from Dominion Day to Canada Day

4. Паннотия – Pannotia formed when Laurentia was located adjacent to the two major South American cratons, Amazonia and Río de la Plata. The opening of the Iapetus Ocean separated Laurentia from Baltica, Amazonia, piper 1976 was probably the first to propose a Proterozoic supercontinent preceding Pangaea, today known as Rodinia. The reconstruction of Bond et al. is virtually identical to that of Dalziel 1997, another term for the supercontinent that is thought to have existed at the end of Neoproterozoic time is Greater Gondwanaland, suggested by Stern 1994. This term recognizes that the supercontinent of Gondwana, which formed at the end of the Neoproterozoic, was part of the much larger end-Neoproterozoic supercontinent. Powell, however, objected to this renaming and instead proposed Stumps term for the latter supercontinent, the formation of Pannotia began during the Pan-African orogeny when the Congo continent got caught between the northern and southern halves of the previous supercontinent Rodinia some 750 Ma. The peak in this mountain building event was around 640–610 Ma, the formation of Pannotia was the result of Rodinia turning itself inside out. When Pannotia had formed Africa was located at the centre surrounded by the rest of Gondwana, South America, Arabia, Madagascar, India, Antarctica, Laurentia, who escaped out of Rodinia, Baltica, and Siberia kept the relative positions they had in Rodinia. The Cathaysian and Cimmerian terranes were located along the margins of east Gondwana. The Avalonian-Cadomian terranes were located along the northern margins of western Gondwana. This orogeny probably extended north into the Uralian margin of Baltica, Pannotia formed by subduction of exterior oceans over a geoid low, whereas Pangaea formed by subduction of interior oceans over a geoid high perhaps caused by superplumes and slab avalanche events. One of the major of these orogenies was the collision between East and West Gondwana or the East African Orogeny, 600-500 Ma two Brazilian interior orogenies got highly deformed and metamorphosed between a series of colliding cratons, Amazonia, West Africa-São Luís, and São Francisco-Congo-Kasai. The material that was accreted included 950-850 Ma mafic meta-igneous complexes, the break-up of Pannotia was accompanied by sea level rise, dramatic changes in climate and ocean water chemistry, and rapid metazoan diversification. Bond, Nickeson & Kominz 1984 found Neoproterozoic passive margin sequences worldwide — the first indication of a Late Neoproterozoic supercontinent, the Iapetus Ocean started to open while Pannotia was being assembled,200 m. y. after the break-up of Rodinia. Plate tectonics Supercontinent cycle Pan-African orogeny An image showing Pannotia according to Christopher Scotese, stampfli, G. M. von Raumer, J. F. Borel, G. D. Paleozoic evolution of pre-Variscan terranes, from Gondwana to the Variscan collision

5. Пангея – Pangaea or Pangea was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from earlier continental units approximately 335 million years ago, in contrast to the present Earth and its distribution of continental mass, much of Pangaea was in the southern hemisphere and surrounded by a superocean, Panthalassa. Pangaea was the most recent supercontinent to have existed and the first to be reconstructed by geologists, the name Pangaea/Pangea is derived from Ancient Greek pan and Gaia. The name Pangea occurs in the 1920 edition of Die Entstehung der Kontinente und Ozeane, but only once, the forming of supercontinents and their breaking up appears to have been cyclical through Earths history. There may have many others before Pangaea. When Rodinia broke up, it split into three pieces, the supercontinent of Proto-Laurasia, the supercontinent of Proto-Gondwana, and the smaller Congo craton, Proto-Laurasia and Proto-Gondwana were separated by the Proto-Tethys Ocean. Next Proto-Laurasia itself split apart to form the continents of Laurentia, Siberia, Baltica moved to the east of Laurentia, and Siberia moved northeast of Laurentia. The splitting also created two new oceans, the Iapetus Ocean and Paleoasian Ocean, most of the above masses coalesced again to form the relatively short-lived supercontinent of Pannotia. This supercontinent included large amounts of land near the poles and, near the equator, Pannotia lasted until 540 Ma, near the beginning of the Cambrian period and then broke up, giving rise to the continents of Laurentia, Baltica, and the southern supercontinent of Gondwana. Baltica, Laurentia, and Avalonia all came together by the end of the Ordovician to form a supercontinent called Euramerica or Laurussia. The collision also resulted in the formation of the northern Appalachians, Siberia sat near Euramerica, with the Khanty Ocean between the two continents. While all this was happening, Gondwana drifted slowly towards the South Pole and this was the first step of the formation of Pangaea. The second step in the formation of Pangaea was the collision of Gondwana with Euramerica, by Silurian time,440 Ma, Baltica had already collided with Laurentia, forming Euramerica. Avalonia had not yet collided with Laurentia, but as Avalonia inched towards Laurentia, meanwhile, southern Europe broke off from Gondwana and began to move towards Euramerica across the newly formed Rheic Ocean. It collided with southern Baltica in the Devonian, though this microcontinent was an underwater plate, the Iapetus Oceans sister ocean, the Khanty Ocean, shrank as an island arc from Siberia collided with eastern Baltica. Behind this island arc was a new ocean, the Ural Ocean, by late Silurian time, North and South China split from Gondwana and started to head northward, shrinking the Proto-Tethys Ocean in their path and opening the new Paleo-Tethys Ocean to their south. In the Devonian Period, Gondwana itself headed towards Euramerica, causing the Rheic Ocean to shrink, South America moved northward to southern Euramerica, while the eastern portion of Gondwana headed toward the South Pole from the equator. North and South China were on independent continents, the Kazakhstania microcontinent had collided with Siberia

6. Канадский щит – Composed of igneous rock resulting from its long volcanic history, the area is covered by a thin layer of soil. Human population is sparse, and industrial development is minimal, while mining is prevalent, the Canadian Shield is a physiographic division, consisting of five smaller, physiographic provinces, the Laurentian Upland, Kazan Region, Davis, Hudson and James. The shield extends into the United States as the Adirondack Mountains, the Canadian Shield is U-shaped and is a subsection of the Laurentia craton signifying the area of greatest glacial impact creating the thin soils. The Canadian Shield is more than 3.96 billion years old, the Canadian Shield once had jagged peaks, higher than any of todays mountains, but millions of years of erosion have changed these mountains to rolling hills. The Canadian Shield was the first part of North America to be elevated above sea level and has remained almost wholly untouched by successive encroachments of the sea upon the continent. It is the Earths greatest area of exposed Archean rock, the metamorphic base rocks are mostly from the Precambrian Supereon, and have been repeatedly uplifted and eroded. Today it consists largely of an area of low relief 300 to 610 m above sea level with a few monadnocks, during the Pleistocene Epoch, continental ice sheets depressed the land surface, scooped out thousands of lake basins, and carried away much of the regions soil. When the Greenland section is included, the Shield is approximately circular, bounded on the northeast by the northeast edge of Greenland and it covers much of Greenland, Labrador, most of Quebec north of the St. In total, the area of the Shield covers approximately 8,000,000 km2. The underlying rock structure also includes Hudson Bay, the Canadian Shield is among the oldest on earth, with regions dating from 2.5 to 4.2 billion years. The multitude of rivers and lakes in the region is caused by the watersheds of the area being so young. It has some of the oldest volcanoes on the planet and it has over 150 volcanic belts whose bedrock ranges from 600 to 1200 million years old. Each belt probably grew by the coalescence of accumulations erupted from numerous vents, many of Canadas major ore deposits are associated with Precambrian volcanoes. The Sturgeon Lake Caldera in Kenora District, Ontario, is one of the worlds best preserved mineralized Neoarchean caldera complexes, the Canadian Shield also contains the Mackenzie dike swarm, which is the largest dike swarm known on Earth. Mountains have deep roots and float on the denser mantle much like an iceberg at sea, as mountains erode, their roots rise and are eroded in turn. The rocks that now form the surface of the Shield were once far below the Earths surface, the high pressures and temperatures at those depths provided ideal conditions for mineralization. Although these mountains are now eroded, many large mountains still exist in Canadas far north called the Arctic Cordillera. This is a vast deeply dissected mountain range, stretching from northernmost Ellesmere Island to the northernmost tip of Labrador, the ranges highest peak is Nunavuts Barbeau Peak at 2,616 metres above sea level

7. Река Святого Лаврентия – The Saint Lawrence River is a large river in the middle latitudes of North America. The Saint Lawrence River flows in a roughly north-easterly direction, connecting the Great Lakes with the Atlantic Ocean and forming the primary drainage outflow of the Great Lakes Basin. It traverses the Canadian provinces of Quebec and Ontario, and is part of the boundary between Ontario, Canada, and the U. S. state of New York. This river also provides the basis of the commercial Saint Lawrence Seaway, the estuary begins at the eastern tip of Île dOrléans, just downstream from Quebec City. The river becomes tidal around Quebec City, the St. Lawrence River runs 3,058 kilometres from the farthest headwater to the mouth and 1,197 km from the outflow of Lake Ontario. The farthest headwater is the North River in the Mesabi Range at Hibbing, the average discharge below the Saguenay River is 16,800 cubic metres per second. At Quebec City, it is 12,101 m3/s, the average discharge at the rivers source, the outflow of Lake Ontario, is 7,410 m3/s. The St. Lawrence River includes Lake Saint-Louis south of Montreal, Lake Saint Francis at Salaberry-de-Valleyfield, pierre Archipelago and the smaller Mingan Archipelago. Other islands include Île dOrléans near Quebec City and Anticosti Island north of the Gaspé and it is the second longest river in Canada. Lake Champlain and the Ottawa, Richelieu, Saguenay, and Saint-François rivers drain into the St. Lawrence. The St. Lawrence River is in an active zone where fault reactivation is believed to occur along late Proterozoic to early Paleozoic normal faults related to the opening of Iapetus Ocean. The faults in the area are related and are called the Saint Lawrence rift system. According to the United States Geological Survey, the St. Lawrence Valley is a province of the larger Appalachian division, containing the Champlain. However, in Canada, where most of the valley is, it is considered part of a distinct Saint Lawrence Lowlands physiographic division. Lawrence River itself was Jacques Cartier, at that time, the land along the river was inhabited by the St. Lawrence Iroquoians, at the time of Cartiers second voyage in 1535. Because Cartier arrived in the estuary on St. Lawrences feast day, the St. Lawrence River is partly within the U. S. and as such is that countrys sixth oldest surviving European place-name. The earliest regular Europeans in the area were the Basques, who came to the St Lawrence Gulf, the Basque whalers and fishermen traded with indigenous Americans and set up settlements, leaving vestiges all over the coast of eastern Canada and deep into the Saint Lawrence River. Basque commercial and fishing activity reached its peak before the Armada Invencibles disaster, initially, the whaling galleons from Labourd were not affected by the Spanish defeat

8. Суперконтинент – In geology, a supercontinent is the assembly of most or all of Earths continental blocks or cratons to form a single large landmass. However, the definition of a supercontinent can be ambiguous, Many earth scientists, such as P. F. Hoffman, use the term supercontinent to mean a clustering of all continents. This definition leaves room for interpretation when labeling a continental body and is easier to apply to Precambrian times, the landmass of Pangaea is the collective name describing all of these continental masses when they were most recently in proximity to one another. This would classify Pangaea as a supercontinent, according to the definition by Rogers and Santosh, a supercontinent does not exist today. Supercontinents have assembled and dispersed multiple times in the geologic past, the positions of continents have been accurately determined back to the early Jurassic. However, beyond 200 Ma, continental positions are less certain. The following table displays historical supercontinents, using a general definition, there are two contrasting models for supercontinent evolution through geological time. The first model theorizes that at least two separate supercontinents existed comprising Vaalbara and Kenorland, the Neoarchean supercontinent consisted of Superia and Sclavia. These parts of Neoarchean age broke off at ~2300 and 2090 Ma, Nuna continued to develop during the Mesoproterozoic, primarily by lateral accretion of juvenile arcs, and in ~1000 Ma Nuna collided with other land masses, forming Rodinia. Between ~800 and 700 Ma Rodinia broke apart, however, before completely breaking up, some fragments of Rodinia had already come together to form Gondwana by ~530 Ma. Pangaea formed by ~300 Ma through the collision of Gondwana, Laurentia, Baltica, during the intervening periods, the poles conform to a unified apparent polar wander path. The explanation for the duration of the Protopangea-Paleopangea supercontinent appears to be that Lid Tectonics prevailed during Precambrian times. Plate Tectonics as seen on the contemporary Earth became dominant only during the part of geological times. The Phanerozoic supercontinent Pangaea began to break up 180 Ma and is doing so today. Because Pangaea is the most recent of Earths supercontinents, it is the most well known, contributing to Pangaeas popularity in the classroom is the fact that its reconstruction is almost as simple as fitting the present continents bordering the Atlantic-type oceans like puzzle pieces. A supercontinent cycle is the break-up of one supercontinent and the development of another, supercontinent cycles are not the same as the Wilson cycle, which is the opening and closing of an individual oceanic basin. The Wilson cycle rarely synchronizes with the timing of a supercontinent cycle, however, supercontinent cycles and Wilson cycles were both involved in the creation of Pangaea and Rodinia

9. Тектоника плит – The theoretical model builds on the concept of continental drift developed during the first few decades of the 20th century. The geoscientific community accepted plate-tectonic theory after seafloor spreading was validated in the late 1950s, the lithosphere, which is the rigid outermost shell of a planet, is broken up into tectonic plates. The Earths lithosphere is composed of seven or eight major plates, where the plates meet, their relative motion determines the type of boundary, convergent, divergent, or transform. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along plate boundaries. The relative movement of the plates typically ranges from zero to 100 mm annually, tectonic plates are composed of oceanic lithosphere and thicker continental lithosphere, each topped by its own kind of crust. Along convergent boundaries, subduction carries plates into the mantle, the material lost is balanced by the formation of new crust along divergent margins by seafloor spreading. In this way, the surface of the lithosphere remains the same. This prediction of plate tectonics is also referred to as the conveyor belt principle, earlier theories, since disproven, proposed gradual shrinking or gradual expansion of the globe. Tectonic plates are able to move because the Earths lithosphere has greater strength than the underlying asthenosphere. Lateral density variations in the result in convection. Plate movement is thought to be driven by a combination of the motion of the seafloor away from the ridge and drag, with downward suction. Another explanation lies in the different forces generated by forces of the Sun. The relative importance of each of these factors and their relationship to other is unclear. The outer layers of the Earth are divided into the lithosphere and asthenosphere and this is based on differences in mechanical properties and in the method for the transfer of heat. Mechanically, the lithosphere is cooler and more rigid, while the asthenosphere is hotter, in terms of heat transfer, the lithosphere loses heat by conduction, whereas the asthenosphere also transfers heat by convection and has a nearly adiabatic temperature gradient. The key principle of plate tectonics is that the lithosphere exists as separate and distinct tectonic plates, Plate motions range up to a typical 10–40 mm/year, to about 160 mm/year. The driving mechanism behind this movement is described below, tectonic lithosphere plates consist of lithospheric mantle overlain by either or both of two types of crustal material, oceanic crust and continental crust. Average oceanic lithosphere is typically 100 km thick, its thickness is a function of its age, as passes, it conductively cools

10. Лавразиотерии – Laurasiatheria is a superorder of placental mammals that originated on the northern supercontinent of Laurasia 99 million years ago. The superorder includes shrews, pangolins, bats, whales, carnivorans, odd-toed and even-toed ungulates, Laurasiatheria was discovered on the basis of the similar gene sequences shared by the mammals belonging to it, no anatomical features have yet been found that unite the group. Laurasiatheria is a clade usually discussed without a Linnaean rank, but has assigned the rank of cohort or magnorder. The Laurasiatheria clade is based on DNA sequence analyses and retrotransposon presence/absence data, the name comes from the theory that these mammals evolved on the supercontinent of Laurasia, after it split from Gondwana when Pangaea broke up. It is a group to Euarchontoglires with which it forms the clade Boreoeutheria. Based on morphological grounds, Chiroptera had long classified in the superorder Archonta until genetic research instead showed their kinship with the other laurasiatherians. Found better support for the latter, while Nery et al. found Perissodactyla to be sister to Carnivora, Laurasiatheria is also posited to include several extinct orders and superorders. At least some of these are considered wastebasket taxons, historically lumping together several lineages based on superficial attributes, in some cases, these orders have turned out to either be paraphyletic assemblages, or to be composed of mammals now understood not to be laurasiatheres at all. Meridiungulata Condylarthra Dinocerata Mesonychia Creodonta Data related to Laurasiatheria at Wikispecies

wikivisually.com

Лаврентия (древний материк) Википедия

Лаврентия — континент, существовавший в палеозойскую эру в восточной и центральной Канаде. Начал формирование 540 млн. л. назад при распаде Паннотии и 335 млн. л. назад объединился с другими континентами в Пангею.

Название континенту дало Лаврентийское плато (Канадский щит), которое в свою очередь так названо по реке Святого Лаврентия.

См. также

• Суперконтинент
• Тектоника плит
• Лавразиотерии

Ссылки

• United Plates of America (англ.). The Dynamic Earth. National Museum of Natural History. Проверено 1 февраля 2017. Архивировано 6 марта 2005 года.

Континенты

wikiredia.ru

Лаврентия (древний материк) Вики

Лаврентия — континент, существовавший в палеозойскую эру в восточной и центральной Канаде. Начал формирование 540 млн. л. назад при распаде Паннотии и 335 млн. л. назад объединился с другими континентами в Пангею.

Название континенту дало Лаврентийское плато (Канадский щит), которое в свою очередь так названо по реке Святого Лаврентия.

См. также[ | код]

• Суперконтинент
• Тектоника плит
• Лавразиотерии

Ссылки[ | код]

• United Plates of America (англ.). The Dynamic Earth. National Museum of Natural History. Проверено 1 февраля 2017. Архивировано 6 марта 2005 года.

Континенты

ru.wikibedia.ru

Лаврентия (древний материк)

См. также

• Суперконтинент
• Тектоника плит
• Лавразиотерии

Ссылки

Лаврентия (древний материк) Информация о

Лаврентия (древний материк) Информация Видео

Лаврентия (древний материк) что, Лаврентия (древний материк) кто, Лаврентия (древний материк) объяснение

There are excerpts from wikipedia on this article and video

www.turkaramamotoru.com

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