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Aquatic Sill
An aquatic sill (or an oceanic sill) is a sea floor barrier of relatively shallow depth (tens to hundreds of meters) that restricts water movement between benthic zones of an oceanic basin or lake bottom. There are roughly 400 sills in the Earth's oceans, covering 0.01% of the seafloor. A classic example is the Strait of Gibraltar Gateway between the Mediterranean Sea and the Atlantic Ocean. Formation processes Aquatic sills are common in fjords, limiting their water exchange with the ocean. After the last ice age, approximately 18,000 years ago, continental glaciers extended to the continental shelves and created U-shaped glacial valleys, with long narrow openings that rise upward near the outer shelf, thereby creating sills. Aquatic sills as barriers Circulation barriers Aquatic sills can influence water circulation by restricting the movement of bottom water masses, resulting in partial to total separation of two basins. The restricted water circulation affects tem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bivalvia
Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed by a calcified exoskeleton consisting of a hinged pair of half-bivalve shell, shells known as valve (mollusc), valves. As a group, bivalves have no head and lack some typical molluscan organs such as the radula and the odontophore. Their gills have evolved into ctenidium (mollusc), ctenidia, specialised organs for feeding and breathing. Common bivalves include clams, oysters, Cockle (bivalve), cockles, mussels, scallops, and numerous other family (biology), families that live in saltwater, as well as a number of families that live in freshwater. Majority of the class are benthic filter feeders that bury themselves in sediment, where they are relatively safe from predation. Others lie on the sea floor or attach themselves to rocks or other h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transtension
Transtension is the state in which a rock mass or area of the Earth's crust (geology), crust experiences both ''extensive'' and ''transtensive'' Shear (geology), shear. As such, transtensional regions are characterised by both extensional structures (fault (geology), normal faults, grabens) and wrench structures (strike-slip faults). In general, many tectonic regimes that were previously defined as simple strike-slip shear zones are actually transtensional. It is unlikely that a deforming body will experience 'pure' extension or 'pure' strike-slip. Transtensional shear zones are characterized by the co-existence of different structures, related to both strike-slip shear and extension. End member structures include pure strike-slip faults and purely extensional ("normal") dip-slip faults. Faults which have components of both (termed 'oblique' slip faults) are abundant. Releasing bend ''Releasing bends'' are transtensional structures that form where the orientation of a strike-slip ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pull-apart Basin
In geology, a basin is a region where subsidence generates accommodation space for the deposition of sediments. A pull-apart basin is a structural basin where two overlapping (en echelon) strike-slip faults or a fault bend create an area of crustal extension undergoing tension, which causes the basin to sink down. Frequently, the basins are rhombic or sigmoidal in shape. Dimensionally, basins are limited to the distance between the faults and the length of overlap.Frisch, Wolfgang, Martin Meschede, and Ronald C. Blakey. ''Plate tectonics: Continental drift and mountain building''. Springer, 2010. Mechanics and fault configuration The inhomogeneity and structural complexity of continental crust causes faults to deviate from a straight course and frequently causes bends or step-overs in fault paths. Bends and step-overs of adjacent faults become favorable locations for extensional and compressional stress or transtension and transpression stress, if the shear motion is ob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58See the 2014 version of the ICS geologic time scale million years ago (Ma). It is the second and most recent epoch of the Neogene Period in the Cenozoic, Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch. Prior to the 2009 revision of the geologic time scale, which placed the four most recent major glaciations entirely within the Pleistocene, the Pliocene also included the Gelasian Stage, which lasted from 2.59 to 1.81 Ma, and is now included in the Pleistocene. As with other older geologic periods, the Stratum, geological strata that define the start and end are well-identified but the exact dates of the start a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Miocene
The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent" because it has 18% fewer modern marine invertebrates than the Pliocene has. The Miocene followed the Oligocene and preceded the Pliocene. As Earth went from the Oligocene through the Miocene and into the Pliocene, the climate slowly cooled towards a series of ice ages. The Miocene boundaries are not marked by distinct global events but by regionally defined transitions from the warmer Oligocene to the cooler Pliocene Epoch. During the Early Miocene, Afro-Arabia collided with Eurasia, severing the connection between the Mediterranean and Indian Oceans, and allowing the interchange of fauna between Eurasia and Africa, including the dispersal of proboscideans and Ape, hominoids into Eurasia. During the late Miocene, the conn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zanclean Flood
The Zanclean flood or Zanclean deluge is theorized to have refilled the Mediterranean Sea 5.33 million years ago. This flooding ended the Messinian salinity crisis and reconnected the Mediterranean Sea to the Atlantic Ocean, although it is possible that even before the flood there were partial connections to the Atlantic Ocean. The re-connection marks the beginning of the Zanclean age (geology), age which is the name given to the earliest age on the geologic time scale of the Pliocene. According to this model, water from the Atlantic Ocean refilled the Endorheic basin, dried-up basin through the modern-day Strait of Gibraltar. Ninety percent of the Mediterranean Basin flooding occurred abruptly during a period estimated to have been between several months and two years, following low water discharges that could have lasted for several thousand years. Sea level rise in the basin may have reached rates at times greater than . Based on the erosion features preserved until mod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Messinian Crisis
In the Messinian salinity crisis (also referred to as the Messinian event, and in its latest stage as the Lago Mare event) the Mediterranean Sea went into a cycle of partial or nearly complete desiccation (drying-up) throughout the latter part of the Messinian age of the Miocene epoch, from 5.96 to 5.33 Ma (million years ago). It ended with the Zanclean flood, when the Atlantic reclaimed the basin. Sediment samples from below the deep seafloor of the Mediterranean Sea, which include evaporite minerals, soils, and fossil plants, show that the precursor of the Strait of Gibraltar closed about 5.96 million years ago, sealing the Mediterranean off from the Atlantic. This resulted in a period of partial desiccation of the Mediterranean Sea, the first of several such periods during the late Miocene. After the strait closed for the last time around 5.6 Ma, the region's generally dry climate at the time dried the Mediterranean basin out nearly completely within a thousand years. This mas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deep-water Coral
The habitat of deep-water corals, also known as cold-water corals, extends to deeper, darker parts of the oceans than tropical corals, ranging from near the surface to the abyss, beyond where water temperatures may be as cold as . Deep-water corals belong to the Phylum Cnidaria and are most often stony corals, but also include black and thorny corals and soft corals including the Gorgonians (sea fans). Like tropical corals, they provide habitat to other species, but deep-water corals do not require zooxanthellae Zooxanthellae (; zooxanthella) is a colloquial term for single-celled photosynthetic organisms that are able to live in symbiosis with diverse marine invertebrates including corals, jellyfish, demosponges, and nudibranchs. Most known zooxanthell ... to survive. While there are nearly as many species of deep-water corals as shallow-water species, only a few deep-water species develop traditional reefs. Instead, they form aggregations called patches, banks, bioher ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fauna
Fauna (: faunae or faunas) is all of the animal life present in a particular region or time. The corresponding terms for plants and fungi are ''flora'' and '' funga'', respectively. Flora, fauna, funga and other forms of life are collectively referred to as '' biota''. Zoologists and paleontologists use ''fauna'' to refer to a typical collection of animals found in a specific time or place, e.g. the " Sonoran Desert fauna" or the " Burgess Shale fauna". Paleontologists sometimes refer to a sequence of faunal stages, which is a series of rocks all containing similar fossils. The study of animals of a particular region is called faunistics. Etymology ''Fauna'' comes from the name Fauna, a Roman goddess of earth and fertility, the Roman god Faunus, and the related forest spirits called Fauns. All three words are cognates of the name of the Greek god Pan, and ''panis'' is the Modern Greek equivalent of fauna (πανίς or rather πανίδα). ''Fauna'' is also the word fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Morocco
Morocco, officially the Kingdom of Morocco, is a country in the Maghreb region of North Africa. It has coastlines on the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to Algeria–Morocco border, the east, and the disputed territory of Western Sahara to Morocco–Western Sahara border, the south. Morocco also claims the Spain, Spanish Enclave and exclave, exclaves of Ceuta, Melilla and Peñón de Vélez de la Gomera, and several small Plazas de soberanía, Spanish-controlled islands off its coast. It has a population of approximately 37 million. Islam is both the official and predominant religion, while Arabic and Berber are the official languages. Additionally, French and the Moroccan dialect of Arabic are widely spoken. The culture of Morocco is a mix of Arab culture, Arab, Berbers, Berber, Culture of Africa, African and Culture of Europe, European cultures. Its capital is Rabat, while its largest city is Casablanca. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iberian Peninsula
The Iberian Peninsula ( ), also known as Iberia, is a peninsula in south-western Europe. Mostly separated from the rest of the European landmass by the Pyrenees, it includes the territories of peninsular Spain and Continental Portugal, comprising most of the region, as well as the tiny adjuncts of Andorra, Gibraltar, and, pursuant to the traditional definition of the Pyrenees as the peninsula's northeastern boundary, a small part of France. With an area of approximately , and a population of roughly 53 million, it is the second-largest European peninsula by area, after the Scandinavian Peninsula. Etymology The Iberian Peninsula has always been associated with the River Ebro (Ibēros in ancient Greek and Ibērus or Hibērus in Latin). The association was so well known it was hardly necessary to state; for example, Ibēria was the country "this side of the Ibērus" in Strabo. Pliny the Elder, Pliny goes so far as to assert that the Greeks had called "the whole of the peninsula" Hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
