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Passive Margin
A passive margin is the transition between Lithosphere#Oceanic lithosphere, oceanic and Lithosphere#Continental lithosphere, continental lithosphere that is not an active plate continental margin, margin. A passive margin forms by sedimentation above an ancient rift, now marked by transitional lithosphere. Continental rifting forms new ocean basins. Eventually the continental rift forms a mid-ocean ridge and the locus of extensional tectonics, extension moves away from the continent-ocean boundary. The transition between the continental and oceanic lithosphere that was originally formed by rifting is known as a passive margin. Global distribution Passive margins are found at every ocean and continent boundary that is not marked by a Fault (geology)#Strike-slip faults, strike-slip fault or a subduction, subduction zone. Passive margins define the region around the Arctic Ocean, Atlantic Ocean, and western Indian Ocean, and define the entire coasts of Africa, Australia, Greenla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rifting To Spreading Transition
In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear Fault (geology), downfaulted depression, called a graben, or more commonly a half-graben with normal faulting and rift-flank uplifts mainly on one side. Where rifts remain above sea level they form a rift valley, which may be filled by water forming a rift lake. The axis of the rift area may contain volcanic rocks, and active volcanism is a part of many, but not all, active rift systems. Major rifts occur along the central axis of most mid-ocean ridges, where new oceanic crust and lithosphere is created along a divergent boundary between two tectonic plates. ''Failed rifts'' are the result of continental rifting that failed to continue to the point of break-up. Typically the transition from rifting to spreading develops at a triple junction where three converging rifts meet over a Hotspot (geology), hotspot. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greenland
Greenland is an autonomous territory in the Danish Realm, Kingdom of Denmark. It is by far the largest geographically of three constituent parts of the kingdom; the other two are metropolitan Denmark and the Faroe Islands. Citizens of Greenland are full Danish nationality law, citizens of Denmark and European Union citizenship, of the European Union. Greenland is one of the Special territories of members of the European Economic Area#Overseas countries and territories, Overseas Countries and Territories of the European Union and is part of the Council of Europe. It is the List of islands by area, world's largest island, and lies between the Arctic Ocean, Arctic and Atlantic oceans, east of the Arctic Archipelago, Canadian Arctic Archipelago. It is the location of the northernmost point of land in the world; Kaffeklubben Island off the northern coast is the world's Northernmost point of land, northernmost undisputed point of land—Cape Morris Jesup on the mainland was thought to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pacific Ocean
The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the continents of Asia and Australia in the west and the Americas in the east. At in area (as defined with a southern Antarctic border), the Pacific Ocean is the largest division of the World Ocean and the hydrosphere and covers approximately 46% of Earth's water surface and about 32% of the planet's total surface area, larger than its entire land area ().Pacific Ocean . ''Encyclopædia Britannica, Britannica Concise.'' 2008: Encyclopædia Britannica, Inc. The centers of both the Land and water hemispheres, water hemisphere and the Western Hemisphere, as well as the Pole of inaccessi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
West Africa
West Africa, also known as Western Africa, is the westernmost region of Africa. The United Nations geoscheme for Africa#Western Africa, United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Liberia, Mali, Mauritania, Niger, Nigeria, Senegal, Sierra Leone, and Togo, as well as Saint Helena, Ascension and Tristan da Cunha (United Kingdom Overseas Territories, United Kingdom Overseas Territory).Paul R. Masson, Catherine Anne Pattillo, "Monetary union in West Africa (ECOWAS): is it desirable and how could it be achieved?" (Introduction). International Monetary Fund, 2001. The population of West Africa is estimated at around million people as of , and at 381,981,000 as of 2017, of which 189,672,000 were female and 192,309,000 male.United Nations Department of Economic and Social Affairs, Population Division (2017). World Population Prospects: The 2017 Revision, custom data acquired via webs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Belt
A volcanic belt is a large volcanically active region. Other terms are used for smaller areas of activity, such as volcanic fields or volcanic systems. Volcanic belts are found above zones of unusually high temperature () where magma is created by partial melting of solid material in the Earth's crust and upper mantle. These areas usually form along tectonic plate boundaries at depths of . For example, volcanoes in Mexico and western North America are mostly in volcanic belts, such as the Trans-Mexican Volcanic Belt that extends from west to east across central-southern Mexico and the Northern Cordilleran Volcanic Province in western Canada. In the case of Iceland, the geologist G.G. Bárdarson in 1929 identified clusters of volcanic belts while studying the Reykjanes Peninsula. The deeply deformed and eroded remnants of ancient volcanic belts are found in volcanically inactive regions such as the Canadian Shield. It contains over 150 volcanic belts (now deformed and eroded d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tectonic Uplift
Tectonic uplift is the orogeny, geologic uplift of Earth#Surface, Earth's surface that is attributed to plate tectonics. While Isostasy, isostatic response is important, an increase in the mean elevation of a region can only occur in response to tectonic processes of Thrust tectonics, crustal thickening (such as Mountain formation, mountain building events), changes in the density distribution of the crust and underlying Mantle (geology), mantle, and flexural support due to the bending of rigid lithosphere. Tectonic uplift results in denudation (processes that wear away the earth's surface) by raising buried rocks closer to the surface. This process can redistribute large loads from an elevated region to a topographically lower area as well – thus promoting an isostatic response in the region of denudation (which can cause local bedrock uplift). The timing, magnitude, and rate of denudation can be estimated by geologists using pressure-temperature studies. Crustal thickening C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convergent Boundary
A convergent boundary (also known as a destructive boundary) is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a plane where many earthquakes occur, called the Wadati–Benioff zone. These collisions happen on scales of millions to tens of millions of years and can lead to volcanism, earthquakes, orogenesis, destruction of lithosphere, and deformation. Convergent boundaries occur between oceanic-oceanic lithosphere, oceanic-continental lithosphere, and continental-continental lithosphere. The geologic features related to convergent boundaries vary depending on crust types. Plate tectonics is driven by convection cells in the mantle. Convection cells are the result of heat generated by the radioactive decay of elements in the mantle escaping to the surface and the return of cool materials from the surface to the mantle. These convection cells bri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plate Tectonics
Plate tectonics (, ) is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of , an idea developed during the first decades of the 20th century. Plate tectonics came to be accepted by Earth science, geoscientists after seafloor spreading was validated in the mid-to-late 1960s. The processes that result in plates and shape Earth's crust are called ''tectonics''. Tectonic plates also occur in other planets and moons. Earth's lithosphere, the rigid outer shell of the planet including the crust (geology), crust and upper mantle, is fractured into seven or eight major plates (depending on how they are defined) and many minor plates or "platelets". Where the plates meet, their relative motion determines the type of plate boundary (or fault (geology), fault): , , or . The relative movement of the plates typically ranges from zero to 10 cm annu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Northeast Asia
Northeast Asia or Northeastern Asia is a geographical Subregion#Asia, subregion of Asia. Its northeastern landmass and islands are bounded by the Pacific Ocean, North Pacific Ocean. The term Northeast Asia was popularized during the 1930s by American historian and political scientist Robert Kerner. Under Kerner's definition, "Northeast Asia" includes the Japanese archipelago, Japanese Archipelago, the Korea, Korean Peninsula, the Mongolian Plateau, the Northeast China Plain, and East Siberian Mountains, the mountainous regions of the Russian Far East, stretching from the Lena (river), Lena River in the west to the Pacific Ocean in the east. Definitions The definition of Northeast Asia is not static but often changes according to the context in which it is discussed. The subregion of Northeast Asia comprises China, Japan, and Korea, usually also including Mongolia and Siberia. Parts or the whole of Northern and southern China, northern China are also frequently included in source ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antarctica
Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. Antarctica is the fifth-largest continent, being about 40% larger than Europe, and has an area of . Most of Antarctica is covered by the Antarctic ice sheet, with an average thickness of . Antarctica is, on average, the coldest, driest, and windiest of the continents, and it has the highest average elevation. It is mainly a polar desert, with annual Climate of Antarctica#Precipitation, precipitation of over along the coast and far less inland. About 70% of the world's freshwater reserves are frozen in Antarctica, which, if melted, would raise global sea levels by almost . Antarctica holds the record for the Lowest temperature recorded on Earth, lowest measured temperature on Earth, . The coastal regions can reach temperatures over in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Western Europe
Western Europe is the western region of Europe. The region's extent varies depending on context. The concept of "the West" appeared in Europe in juxtaposition to "the East" and originally applied to the Western half of the ancient Mediterranean world, the Latin West of the Roman Empire, and "Western Christendom". Beginning with the Renaissance and the Age of Discovery, roughly from the 15th century, the concept of ''Europe'' as "the Western world, West" slowly became distinguished from and eventually replaced the dominant use of "Christendom" as the preferred endonym within the area. By the Age of Enlightenment and the Industrial Revolution, the concepts of "Eastern Europe" and "Western Europe" were more regularly used. The distinctiveness of Western Europe became most apparent during the Cold War, when Europe was divided for 40 years by the Iron Curtain into the Western Bloc and Eastern Bloc, each characterised by distinct political and economical systems. Historical divisions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
