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Pseudo-atoll
A pseudo-atoll, like an atoll, is an island that encircles a lagoon, either partially or completely. A pseudo-atoll differs from an atoll as established by several authorities, such as how it is formed (not by subsidence, nor by coral). It is considered a preferable term to "near-atoll". There is a need for rigorous definition of "pseudo-atoll" before it can be accepted as a general term. Definitions Alexander Agassiz gave the term pseudo-atoll to "any ring-shaped reefs not formed as a result of subsidence". while Norman D. Newell and J. Keith Rigby called such reefs non-coral. and "We conclude that almost-atoll should be retained as a descriptive term as defined by Davis and Tayama, and that the use of "near-atoll" as a synonym be abandoned. The value of terms such as "semi-atoll" and "pseudo-atoll" needs close examination and more rigorous definition before being generally accepted." H. Mergner yet states that micro-atolls classify as pseudo-atolls. Professor David R. Stoddart of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reef
A reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic processes— deposition of sand, wave erosion planing down rock outcrops, etc.—but there are also reefs such as the coral reefs of tropical waters formed by biotic processes dominated by corals and coralline algae, and artificial reefs such as shipwrecks and other anthropogenic underwater structures may occur intentionally or as the result of an accident, and sometimes have a designed role in enhancing the physical complexity of featureless sand bottoms, to attract a more diverse assemblage of organisms. Reefs are often quite near to the surface, but not all definitions require this. Earth's largest coral reef system is the Great Barrier Reef in Australia, at a length of over . Biotic There is a variety of biotic reef types, including oyster reefs and sponge reefs, but the most massive and widely ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coral Reef
A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups. Coral belongs to the class Anthozoa in the animal phylum Cnidaria, which includes sea anemones and jellyfish. Unlike sea anemones, corals secrete hard carbonate exoskeletons that support and protect the coral. Most reefs grow best in warm, shallow, clear, sunny and agitated water. Coral reefs first appeared 485 million years ago, at the dawn of the Early Ordovician, displacing the microbial and sponge reefs of the Cambrian. Sometimes called ''rainforests of the sea'', shallow coral reefs form some of Earth's most diverse ecosystems. They occupy less than 0.1% of the world's ocean area, about half the area of France, yet they provide a home for at least 25% of all marine species, including fish, mollusks, worms, crustaceans, echinoderms, sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atoll
An atoll () is a ring-shaped island, including a coral rim that encircles a lagoon partially or completely. There may be coral islands or cays on the rim. Atolls are located in warm tropical or subtropical oceans and seas where corals can grow. Most of the approximately 440 atolls in the world are in the Pacific Ocean. Two different, well-cited models, the subsidence and antecedent karst models, have been used to explain the development of atolls.Droxler, A.W. and Jorry, S.J., 2021. ''The Origin of Modern Atolls: Challenging Darwin's Deeply Ingrained Theory.'' ''Annual Review of Marine Science'', 13, pp.537-573. According to Charles Darwin's ''subsidence model'', the formation of an atoll is explained by the subsidence of a volcanic island around which a coral fringing reef has formed. Over geologic time, the volcanic island becomes extinct and eroded as it subsides completely beneath the surface of the ocean. As the volcanic island subsides, the coral fringing reef becomes a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Island
An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An island in a river or a lake island may be called an eyot or ait, and a small island off the coast may be called a holm. Sedimentary islands in the Ganges delta are called chars. A grouping of geographically or geologically related islands, such as the Philippines, is referred to as an archipelago. There are two main types of islands in the sea: continental and oceanic. There are also artificial islands, which are man-made. Etymology The word ''island'' derives from Middle English ''iland'', from Old English ''igland'' (from ''ig'' or ''ieg'', similarly meaning 'island' when used independently, and -land carrying its contemporary meaning; cf. Dutch ''eiland'' ("island"), German ''Eiland'' ("small island")). However, the spelling of the word ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lagoon
A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') and ''atoll lagoons''. They have also been identified as occurring on mixed-sand and gravel coastlines. There is an overlap between bodies of water classified as coastal lagoons and bodies of water classified as estuaries. Lagoons are common coastal features around many parts of the world. Definition and terminology Lagoons are shallow, often elongated bodies of water separated from a larger body of water by a shallow or exposed shoal, coral reef, or similar feature. Some authorities include fresh water bodies in the definition of "lagoon", while others explicitly restrict "lagoon" to bodies of water with some degree of salinity. The distinction between "lagoon" and "estuary" also varies between authorities. Richard A. Davis Jr. restrict ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subsidence
Subsidence is a general term for downward vertical movement of the Earth's surface, which can be caused by both natural processes and human activities. Subsidence involves little or no horizontal movement, which distinguishes it from slope movement. Processes that lead to subsidence include dissolution of underlying carbonate rock by groundwater; gradual compaction of sediments; withdrawal of fluid lava from beneath a solidified crust of rock; mining; pumping of subsurface fluids, such as groundwater or petroleum; or warping of the Earth's crust by tectonic forces. Subsidence resulting from tectonic deformation of the crust is known as tectonic subsidence and can create accommodation for sediments to accumulate and eventually lithify into sedimentary rock. Ground subsidence is of global concern to geologists, geotechnical engineers, surveyors, engineers, urban planners, landowners, and the public in general.National Research Council, 1991. ''Mitigating losses from land subsi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coral
Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton. A coral "group" is a colony of very many genetically identical polyps. Each polyp is a sac-like animal typically only a few millimeters in diameter and a few centimeters in height. A set of tentacles surround a central mouth opening. Each polyp excretes an exoskeleton near the base. Over many generations, the colony thus creates a skeleton characteristic of the species which can measure up to several meters in size. Individual colonies grow by asexual reproduction of polyps. Corals also breed sexually by spawning: polyps of the same species release gametes simultaneously overnight, often around a full moon. Fertilized eggs form planulae, a mobile early form of the coral polyp which, when m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Norman D
Norman or Normans may refer to: Ethnic and cultural identity * The Normans, a people partly descended from Norse Vikings who settled in the territory of Normandy in France in the 10th and 11th centuries ** People or things connected with the Norman conquest of southern Italy in the 11th and 12th centuries ** Norman dynasty, a series of monarchs in England and Normandy ** Norman architecture, romanesque architecture in England and elsewhere ** Norman language, spoken in Normandy ** People or things connected with the French region of Normandy Arts and entertainment * ''Norman'' (film), a 2010 drama film * '' Norman: The Moderate Rise and Tragic Fall of a New York Fixer'', a 2016 film * ''Norman'' (TV series), a 1970 British sitcom starring Norman Wisdom * ''The Normans'' (TV series), a documentary * "Norman" (song), a 1962 song written by John D. Loudermilk and recorded by Sue Thompson * "Norman (He's a Rebel)", a song by Mo-dettes from ''The Story So Far'', 1980 Businesses * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of California, Berkeley
The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public land-grant research university in Berkeley, California. Established in 1868 as the University of California, it is the state's first land-grant university and the founding campus of the University of California system. Its fourteen colleges and schools offer over 350 degree programs and enroll some 31,800 undergraduate and 13,200 graduate students. Berkeley ranks among the world's top universities. A founding member of the Association of American Universities, Berkeley hosts many leading research institutes dedicated to science, engineering, and mathematics. The university founded and maintains close relationships with three national laboratories at Berkeley, Livermore and Los Alamos, and has played a prominent role in many scientific advances, from the Manhattan Project and the discovery of 16 chemical elements to breakthroughs in computer science and genomics. Berkeley is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Everglades Pseudoatoll
The Everglades Pseudoatoll (also called a pseudo-atoll) was a major geomorphic feature of southern Florida during the Pliocene epoch. Origin The Everglades Pseudoatoll began its growth during the early Eocene as a paleodepression possibly created by an asteroid impact upon the carbonate Florida Platform at the southern part of what is now Everglades National Park. The pseudo-atoll is surrounded by a raised rim. Its growth as a reef system and pseudo-atoll began during the Oligocene reaching its maximum size of north to south during the Piacenzian of the late Pliocene. (Petuch, 163). Description The Everglades Pseudoatoll was a U-shaped asymmetrical system of reefs that surrounded the Okeechobean Sea, not unlike South Pacific atolls surrounded by a central lagoon. The west side was more developed than the east and south, as was the remainder of the west side. On the western side of this pseudo-atoll lay the Immokalee Reef Tract and chain of islands called the Immokalee Archipe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Depression (geology)
In geology, a depression is a landform sunken or depressed below the surrounding area. Depressions form by various mechanisms. Types Erosion-related: * Blowout: a depression created by wind erosion typically in either a partially vegetated sand dune ecosystem or dry soils (such as a post-glacial loess environment). * Glacial valley: a depression carved by erosion by a glacier. * River valley: a depression carved by fluvial erosion by a river. * Area of subsidence caused by the collapse of an underlying structure, such as sinkholes in karst terrain. * Sink: an endorheic depression generally containing a persistent or intermittent (seasonal) lake, a salt flat (playa) or dry lake, or an ephemeral lake. * Panhole: a shallow depression or basin eroded into flat or gently sloping, cohesive rock.Twidale, C.R., and Bourne, J.A., 2018Rock basins (gnammas) revisited.''Géomorphologie: Relief, Processus, Environnement,'' Vol. 24, No. 2. January 2018. Retrieved 9 June 2020. Coll ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atolls
An atoll () is a ring-shaped island, including a coral rim that encircles a lagoon partially or completely. There may be coral islands or cays on the rim. Atolls are located in warm tropical or subtropical oceans and seas where corals can grow. Most of the approximately 440 atolls in the world are in the Pacific Ocean. Two different, well-cited models, the subsidence and antecedent karst models, have been used to explain the development of atolls.Droxler, A.W. and Jorry, S.J., 2021. ''The Origin of Modern Atolls: Challenging Darwin's Deeply Ingrained Theory.'' ''Annual Review of Marine Science'', 13, pp.537-573. According to Charles Darwin's ''subsidence model'', the formation of an atoll is explained by the subsidence of a volcanic island around which a coral fringing reef has formed. Over geologic time, the volcanic island becomes extinct and eroded as it subsides completely beneath the surface of the ocean. As the volcanic island subsides, the coral fringing reef becomes a b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
