|
Geological Shoulder
In geology, a geological shoulder or rift shoulder is an area of uplifted terrain resulting from the compensatory movement of large-scale tectonic processes. These features are distinct from reliefs caused by Continental collision, compressional tectonics, as they arise from Extensional tectonics, extensional forces rather than compression. Geological shoulder Rift shoulders are significant topographic features, often reaching elevations of several kilometers, that form mountainous belts along the edges of central rift depressions. The origin of these shoulders has been the subject of extensive research since the 1980s. The isostatic compensation model proposed by Felix Andries Vening Meinesz in 1950, also known as the Isostasy, isostatic or Flexural strength, flexural rebound model, explains the permanent topographic uplift that occurs during rifting and persists on passive margins despite erosion. This model is complemented by additional theories that account for factors suc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rift Shoulders
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] |
East African Rift
The East African Rift (EAR) or East African Rift System (EARS) is an active continental rift zone in East Africa. The EAR began developing around the onset of the Miocene, 22–25 million years ago. It was formerly considered to be part of a larger Great Rift Valley that extended north to Asia Minor. A narrow zone, the rift is a developing divergent tectonic plate boundary where the African plate is in the process of splitting into two tectonic plates, called the Somali plate and the Nubian plate, at a rate of per year. The rift system consists of three microplates, the Victoria microplate to the north, and the Rovuma and Lwandle microplates to the south. The Victoria microplate is rotating anti-clockwise with respect to the African plate. Its rotation is caused by the configuration of mechanically weaker and stronger lithospheric regions in the EARS. Many of the African Great Lakes lie within the Rift Valley. Extent A series of distinct rift basins, the East A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tectonics
Tectonics ( via Latin ) are the processes that result in the structure and properties of the Earth's crust and its evolution through time. The field of ''planetary tectonics'' extends the concept to other planets and moons. These processes include those of orogeny, mountain-building, the growth and behavior of the strong, old cores of continents known as cratons, and the ways in which the relatively rigid tectonic plate, plates that constitute the Earth's outer shell interact with each other. Principles of tectonics also provide a framework for understanding the earthquake and volcanic belts that directly affect much of the global population. Tectonic studies are important as guides for economic geology, economic geologists searching for fossil fuels and ore deposits of metallic and nonmetallic resources. An understanding of tectonic principles can help geomorphology, geomorphologists to explain Erosion and tectonics, erosion patterns and other Earth-surface features. Ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Structural Geology
Structural geology is the study of the three-dimensional distribution of rock units with respect to their deformational histories. The primary goal of structural geology is to use measurements of present-day rock geometries to uncover information about the history of deformation ( strain) in the rocks, and ultimately, to understand the stress field that resulted in the observed strain and geometries. This understanding of the dynamics of the stress field can be linked to important events in the geologic past; a common goal is to understand the structural evolution of a particular area with respect to regionally widespread patterns of rock deformation (e.g., mountain building, rifting) due to plate tectonics. Use and importance The study of geologic structures has been of prime importance in economic geology, both petroleum geology and mining geology. Folded and faulted rock strata commonly form traps that accumulate and concentrate fluids such as petroleum and natural gas. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mantle Convection
Mantle convection is the very slow creep of Earth's solid silicate mantle as convection currents carry heat from the interior to the planet's surface. Mantle convection causes tectonic plates to move around the Earth's surface. The Earth's lithosphere rides atop the asthenosphere, and the two form the components of the upper mantle. The lithosphere is divided into tectonic plates that are continuously being created or consumed at plate boundaries. Accretion occurs as mantle is added to the growing edges of a plate, associated with seafloor spreading. Upwelling beneath the spreading centers is a shallow, rising component of mantle convection and in most cases not directly linked to the global mantle upwelling. The hot material added at spreading centers cools down by conduction and convection of heat as it moves away from the spreading centers. At the consumption edges of the plate, the material has thermally contracted to become dense, and it sinks under its own weight i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geomorphology
Geomorphology () is the scientific study of the origin and evolution of topographic and bathymetric features generated by physical, chemical or biological processes operating at or near Earth's surface. Geomorphologists seek to understand why landscapes look the way they do, to understand landform and terrain history and dynamics and to predict changes through a combination of field observations, physical experiments and numerical modeling. Geomorphologists work within disciplines such as physical geography, geology, geodesy, engineering geology, archaeology, climatology, and geotechnical engineering. This broad base of interests contributes to many research styles and interests within the field. Overview Earth's surface is modified by a combination of surface processes that shape landscapes, and geologic processes that cause tectonic uplift and subsidence, and shape the coastal geography. Surface processes comprise the action of water, wind, ice, wildfire, and lif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mascarene Basin
The Mascarene Basin is an oceanic basin in the western Indian Ocean. It was formed as the tectonic plate of the Indian subcontinent pulled away from the Madagascar Plate about 66–90 Mya, following the breaking up of the Gondwana supercontinent. The Mascarene Basin is bounded on the west by the island of Madagascar, i.e. the Precambrian Madagascar Massif. It is separated from the Western and Eastern Somali Basins to the north and northeast by the island arc from the northern tip of Madagascar, the Farquhar Islands, the Amirante Islands and Amirante Plateau, the Seychelles Plateau and the Mascarene Plateau. To the southwest and south it is separated from the Madagascar Basin by a continuation of the island arc through Mauritius Island and Reunion Island, the Mauritius Fracture Zone, a fracture zone trending approximately NE-SW, located east of Mauritius Island, and the northwestern edge of the Madagascar Ridge. The approximate center of the basin is . See also * G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scandinavia
Scandinavia is a subregion#Europe, subregion of northern Europe, with strong historical, cultural, and linguistic ties between its constituent peoples. ''Scandinavia'' most commonly refers to Denmark, Norway, and Sweden. It can sometimes also refer to the Scandinavian Peninsula (which excludes Denmark but includes a part of northern Finland). In English usage, Scandinavia is sometimes used as a synonym for Nordic countries. Iceland and the Faroe Islands are sometimes included in Scandinavia for their Ethnolinguistics, ethnolinguistic relations with Sweden, Norway and Denmark. While Finland differs from other Nordic countries in this respect, some authors call it Scandinavian due to its economic and cultural similarities. The geography of the region is varied, from the Norwegian fjords in the west and Scandinavian mountains covering parts of Norway and Sweden, to the low and flat areas of Denmark in the south, as well as archipelagos and lakes in the east. Most of the population ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Continental Margin
A continental margin is the outer edge of continental crust abutting oceanic crust under coastal waters. It is one of the three major zones of the ocean floor, the other two being deep-ocean basins and mid-ocean ridges. The continental margin consists of three different features: the continental rise, the continental slope, and the continental shelf. Continental margins constitute about 28% of the oceanic area. Subzones The continental shelf is the relatively shallow water area found in proximity to continents; it is the portion of the continental margin that transitions from the shore out towards to ocean. Continental shelves are believed to make up 7% of the sea floor. The width of continental shelves worldwide varies in the range of 0.03–1500 km. The continental shelf is generally flat, and ends at the shelf break, where there is a drastic increase in slope angle: The mean angle of continental shelves worldwide is 0° 07′, and typically steeper closer to the c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bay Of Biscay
The Bay of Biscay ( ) is a gulf of the northeast Atlantic Ocean located south of the Celtic Sea. It lies along the western coast of France from Point Penmarc'h to the Spanish border, and along the northern coast of Spain, extending westward to Cape Ortegal. The average depth is and the greatest depth is . Etymology The Bay of Biscay is known in Spain as the Gulf of Biscay (; ). In France, it is called the Gulf of Gascony ( ; ; ; ). In Latin, the bay was known as ( Cantabrian Gulf); the name Cantabrian Sea is still used locally for the southern area of the Bay of Biscay that washes over the northern coast of Spain ( Cantabria). The English name comes from Biscay on the northern Spanish coast, probably standing for the western Basque districts (''Biscay'' up to the early 19th century). Geography Parts of the continental shelf extend far into the bay, resulting in fairly shallow waters in many areas and thus the rough seas for which the region is known. Heavy storms ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Armorican Massif
The Armorican Massif (, ) is a geologic massif that covers a large area in the northwest of France, including Brittany, the western part of Normandy and the Pays de la Loire. It is important because it is connected to Dover on the British side of the English Channel and there has been tilting back and forth that has controlled the geography on both sides. Its name comes from the old Armorica, a Gauls, Gaul area between the rivers Loire and Seine. The massif is composed of metamorphic rock, metamorphic and magmatic rocks that were metamorphism, metamorphosed and/or Deformation (geology), deformed during the Variscan orogeny, Hercynian or Variscan orogeny (400 to 280 million years ago) and the earlier Cadomian orogeny (650 to 550 million years ago). The region was tectonic uplift, uplifted when the Bay of Biscay opened during the Cretaceous period (geology), period. The Cantabrian Mountains and the Armorican Massif were then rift shoulders of the Bay of Biscay. The competence (geo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cantabrian Mountains
The Cantabrian Mountains or Cantabrian Range () are one of the main systems of mountain ranges in Spain. They stretch for over 300 km (180 miles) across northern Spain, from the western limit of the Pyrenees to the Galician Massif in Galicia, along the coast of the Cantabrian Sea. Their easternmost end meets the Sistema Ibérico. These mountains are a distinct physiographic province of the larger Alpine System physiographic division. The Cantabrian Mountains offer a wide range of trails for hiking, as well as many challenging climbing routes. Skiing is possible in the ski resorts of Alto Campoo, Valgrande-Pajares, Fuentes de Invierno, San Isidro, Leitariegos and Manzaneda. Geography The Cantabrian Mountains stretch east–west, nearly parallel to the Cantabrian Sea, as far as the Pass of Leitariegos, also extending south between León and Galicia. The range's western boundary is marked by the valley of the river Minho (), by the lower Sil, which flows into ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
