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Chalk Formation
The Chalk Group (often just called the Chalk) is the lithostratigraphic unit (a certain number of rock strata) which contains the Upper Cretaceous limestone succession in southern and eastern England. The same or similar rock sequences occur across the wider northwest European chalk 'province'. It is characterised by thick deposits of chalk, a soft porous white limestone, deposited in a marine environment. Chalk is a limestone that consists of coccolith biomicrite. A biomicrite is a limestone composed of fossil debris ("bio") and calcium carbonate mud ("micrite"). Most of the fossil debris in chalk consists of the microscopic plates, which are called coccoliths, of microscopic green algae known as coccolithophores. In addition to the coccoliths, the fossil debris includes a variable, but minor, percentage of the fragments of foraminifera, ostracods and mollusks. The coccolithophores lived in the upper part of the water column. When they died, the microscopic calcium carbonate pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seven Sisters, Sussex
The Seven Sisters are a series of chalk sea cliffs on the English Channel coast, and are a stretch of the sea-eroded section of the South Downs range of hills, in the county of East Sussex, in south-east England. The Seven Sisters cliffs run between the mouth of the River Cuckmere near Seaford, and the chalk headland of Beachy Head outside of Eastbourne. The dips or swales that separate each of the seven crests from the next are the remnants of dry valleys in the chalk South Downs which are being gradually eroded by the sea. Some of the cliffs and adjacent countryside make up the Seven Sisters Country Park, which is bounded on its inland side by the A259 road, and is itself a part of the larger South Downs National Park. Cliffs From west to east, the sequence starts just east of Cuckmere Haven. The cliff peaks and the dips between them are individually named. Listed below, the peaks are in italics. There are seven hills, with an eighth one being created by the erosion of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Europe
Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia and it is located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. Comprising the westernmost peninsulas of Eurasia, it shares the continental landmass of Afro-Eurasia with both Africa and Asia. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south and Asia to the east. Europe is commonly considered to be Boundaries between the continents of Earth#Asia and Europe, separated from Asia by the drainage divide, watershed of the Ural Mountains, the Ural (river), Ural River, the Caspian Sea, the Greater Caucasus, the Black Sea and the waterways of the Turkish Straits. "Europe" (pp. 68–69); "Asia" (pp. 90–91): "A commonly accepted division between Asia and E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pelagic Sediment
Pelagic sediment or pelagite is a fine-grained sediment that accumulates as the result of the settling of particles to the floor of the open ocean, far from land. These particles consist primarily of either the microscopic, calcareous or siliceous shells of phytoplankton or zooplankton; clay-size siliciclastic sediment; or some mixture of these. Trace amounts of meteoric dust and variable amounts of volcanic ash also occur within pelagic sediments. Based upon the composition of the ooze, there are three main types of pelagic sediments: siliceous oozes, calcareous oozes, and red clays.Rothwell, R.G., (2005) ''Deep Ocean Pelagic Oozes'', Vol. 5. of Selley, Richard C., L. Robin McCocks, and Ian R. Plimer, Encyclopedia of Geology, Oxford: Elsevier Limited. HüNeke, H., and T. Mulder (2011) ''Deep-Sea Sediments''. Developments in Sedimentology, vol. 63. Elsiever, New York. 849 pp. The composition of pelagic sediments is controlled by three main factors. The first factor is the dis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcareous
Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines. In zoology ''Calcareous'' is used as an adjectival term applied to anatomical structures which are made primarily of calcium carbonate, in animals such as gastropods, i.e., snails, specifically about such structures as the operculum, the clausilium, and the love dart. The term also applies to the calcium carbonate tests of often more or less microscopic Foraminifera. Not all tests are calcareous; diatoms and radiolaria have siliceous tests. The molluscs are calcareous, as are calcareous sponges ( Porifera), that have spicules which are made of calcium carbonate. In botany ''Calcareous grassland'' is a form of grassland characteristic of soils containing much calcium carbonate from underlying chalk or limestone rock. In medicine The term is used in pathology, for example i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mollusca
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is estimated between 60,000 and 100,000 additional species. The proportion of undescribed species is very high. Many taxa remain poorly studied. Molluscs are the largest marine phylum, comprising about 23% of all the named marine organisms. Numerous molluscs also live in freshwater and terrestrial habitats. They are highly diverse, not just in size and anatomical structure, but also in behaviour and habitat. The phylum is typically divided into 7 or 8 taxonomic classes, of which two are entirely extinct. Cephalopod molluscs, such as squid, cuttlefish, and octopuses, are among the most neurologically advanced of all invertebrates—and either the giant squid or the colossal squid is the largest known invertebrate species. The gastropod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ostracod
Ostracods, or ostracodes, are a class of the Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 70,000 species (only 13,000 of which are extant) have been identified, grouped into several orders. They are small crustaceans, typically around in size, but varying from in the case of ''Gigantocypris''. Their bodies are flattened from side to side and protected by a bivalve-like, chitinous or calcareous valve or "shell". The hinge of the two valves is in the upper (dorsal) region of the body. Ostracods are grouped together based on gross morphology. While early work indicated the group may not be monophyletic and early molecular phylogeny was ambiguous on this front, recent combined analyses of molecular and morphological data found support for monophyly in analyses with broadest taxon sampling. Ecologically, marine ostracods can be part of the zooplankton or (most commonly) are part of the benthos, living on or inside the upper layer of the sea floor. While Myodoc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foraminifera
Foraminifera (; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular Ectoplasm (cell biology), ectoplasm for catching food and other uses; and commonly an external shell (called a "Test (biology), test") of diverse forms and materials. Tests of chitin (found in some simple genera, and Textularia in particular) are believed to be the most primitive type. Most foraminifera are marine, the majority of which live on or within the seafloor sediment (i.e., are benthos, benthic), while a smaller number float in the water column at various depths (i.e., are planktonic), which belong to the suborder Globigerinina. Fewer are known from freshwater or brackish conditions, and some very few (nonaquatic) soil species have been identified through molecular analysis of small subunit ribosomal DNA. Foraminifera typically produce a test (biology), test, or shell, which can have eithe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coccolithophore
Coccolithophores, or coccolithophorids, are single celled organisms which are part of the phytoplankton, the autotrophic (self-feeding) component of the plankton community. They form a group of about 200 species, and belong either to the kingdom Protista, according to Robert Whittaker's Five kingdom classification, or clade Hacrobia, according to a newer biological classification system. Within the Hacrobia, the coccolithophores are in the phylum or division Haptophyta, class Prymnesiophyceae (or Coccolithophyceae). Coccolithophores are almost exclusively marine, are photosynthetic, and exist in large numbers throughout the sunlight zone of the ocean. Coccolithophores are the most productive calcifying organisms on the planet, covering themselves with a calcium carbonate shell called a ''coccosphere''. However, the reasons they calcify remains elusive. One key function may be that the coccosphere offers protection against microzooplankton predation, which is one of the ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Micrite
Micrite is a limestone constituent formed of calcareous particles ranging in diameter up to four μm formed by the recrystallization of lime mud. Flügel, Erik, ''Microfacies of Carbonate Rocks: Analysis, Interpretation and Application,'' Springer, pp 74-94, 2004 The term was coined in 1959 by Robert Folk for his carbonate rock classification system. Micrite is derived from MICRocrystalline calcITE. In the Folk classification micrite is a carbonate rock dominated by fine-grained calcite. Carbonate rocks that contain fine-grained calcite in addition to allochems are named ''intramicrite'', ''oomicrite'', ''biomicrite'' or ''pelmicrite'' under the Folk classification depending on the dominant allochem. Micrite is lime mud, carbonate of mud grade. Micrite as a component of carbonate rocks can occur as a matrix, as micrite envelopes around allochems or as peloids Peloids are allochems that are composed of micrite, irrespective of size, shape, or origin. The two primary types of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the ''fossil record''. Paleontology is the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years old to 4.1 billion years old. Early edition, published online before print. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coccolith
Coccoliths are individual plates or scales of calcium carbonate formed by coccolithophores (single-celled phytoplankton such as ''Emiliania huxleyi'') and cover the cell surface arranged in the form of a spherical shell, called a ''coccosphere''. Overview Coccolithophores are spherical cells about 5–100 micrometres across, enclosed by calcareous plates called coccoliths, which are about 2–25 micrometres across. Coccolithophores are an important group of about 200 marine phytoplankton species which cover themselves with a calcium carbonate shell called a "coccosphere". They are ecologically and biogeochemically important but the reason why they calcify remains elusive. One key function may be that the coccosphere offers protection against microzooplankton predation, which is one of the main causes of phytoplankton death in the ocean. Material was copied from this source, which is available under Creative Commons Attribution 4.0 International License File:Cross section of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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