1.
Feces
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Feces or faeces are the solid or semisolid metabolic waste from an animals digestive tract, discharged through the anus or cloaca during a process called defecation. Urine and feces together are called excreta, collected feces has various uses, namely as fertilizer or soil conditioner in agriculture, as a fuel source, or for medicinal purposes. After an animal has digested eaten material, the remains of material are discharged from its body as waste. Although it is lower in energy than the food from which it is derived, feces may retain a large amount of energy and this means that of all food eaten, a significant amount of energy remains for the decomposers of ecosystems. Many organisms feed on feces, from bacteria to fungi to insects such as dung beetles, some may specialize in feces, while others may eat other foods as well. Feces serve not only as a food, but also as a supplement to the usual diet of some animals. Feces and urine, which reflect light, are important to raptors such as kestrels. Seeds also may be found in feces, animals who eat fruit are known as frugivores. An advantage for a plant in having fruit is that animals will eat the fruit and this mode of seed dispersal is highly successful, as seeds dispersed around the base of a plant are unlikely to succeed and often are subject to heavy predation. Provided the seed can withstand the pathway through the system, it is not only likely to be far away from the parent plant. This cycling of matter is known as the biogeochemical cycle, the distinctive odor of feces is due to bacterial action. Gut flora produce compounds such as indole, skatole, and thiols and these are the same compounds that are responsible for the odor of flatulence. Consumption of foods prepared with spices may result in the spices being undigested, the perceived bad odor of feces has been hypothesized to be a deterrent for humans, as consuming or touching it may result in sickness or infection. Human perception of the odor may be contrasted by an animals perception of it, for example. In humans and depending on the individual and the circumstances, defecation may occur daily, extensive hardening of the feces may cause prolonged interruption in the routine and is called constipation. Human fecal matter varies significantly in appearance, depending on diet, normally it is semisolid, with a mucus coating. The brown coloration comes from a combination of bile and bilirubin, in newborn babies, initially fecal matter is yellow-green after the meconium. This coloration comes from the presence of bile alone, throughout the life of an ordinary human, one may experience many types of feces
2.
Eolianite
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Eolianite or aeolianite is any rock formed by the lithification of sediment deposited by aeolian processes, that is, the wind. It is also known as kurkar in the Middle East, miliolite in India and Arabia, eolianite occurs in many parts of the world. It occurs most extensively between the latitudes of 20° and 40° in both hemispheres, with little nearer the equator, and virtually no deposits nearer the poles. There is no apparent difference in distribution between the hemispheres, but if the extent and thickness of deposits are taken into account, on the west coast, there are over 800 kilometres of eolianite cliffs, which are over 150 metres thick in some places. These cliffs, locally known as the Tamala Limestone Formation, contain layers of dune origin interspersed with layers of shallow-marine origin. Other substantial deposits occur in Bermuda, the Bahamas, the southern and eastern coasts of South Africa, the Mediterranean, India, and oceanic islands of the Pacific, Atlantic, Sedimentary rock Facies Sedimentary depositional environment Brooke, Brendan
3.
Long Island, Bahamas
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Long Island is an island in the Bahamas that is split by the Tropic of Cancer. Long Island is one of the Districts of the Bahamas and is known as the most scenic island in the Bahamas, Long Island is about 130 kilometers long and 6 km wide at its widest point. The land area is 596 km2, Long Island is situated about 265 km southeast of the Bahamian capital of Nassau, which is located on the island of New Providence. The Tropic of Cancer runs through the quarter of the island. The northeast side of Long Island is noted for its steep rocky headlands, the terrain ranges widely throughout the island, including white flat expanses from which salt is extracted, swamplands, beaches, and sloping and low hills. Long Island is particularly noted for its caves, which have played a role in the islands history. Long Island is surrounded by small bays and inlets, including the large New Found Harbor west of Deadmans Cay, there are also smaller islands off-shore, including Sandy Cay. The island was called by the Arawak name Yuma. It was rechristened Fernandina by Christopher Columbus on his first voyage in 1492, during which Long Island is believed to have been his third stop, following San Salvador and Rum Cay to the east. Archaeological evidence, including ceremonial stools called duhos, shows that the Lucayan Taíno tribe settled on Long Island, after the demise of the Lucayans, who were carried as slaves to Hispaniola and Cuba, there was no large settlement until the arrival of the Loyalists. The original Loyalists were mainly from New England and New Jersey and these families started the first farms, primarily raising cattle and sheep. By the 1790s, settlers began to arrive from the Carolinas, the plantations flourished for only a few years and, by the time of the abolition of slavery in 1834, most had collapsed and been abandoned. There are many ruins from this era today, the majority of which are overgrown by bush, there are also remains of some of the houses built after slavery, which are usually small and built of stone. Originally, they had thatched roofs, today, most are shingled, the descendants of these families continue to be widespread on the island. Clarence Town, located in the portion of the island, has a population 86 people. Nearby Deadmans Cay is the settlement at the center of the island and is home to Deadmans Cay Airport. Mangrove Bush is the home of the islands boat-building trade, while Hamiltons is noted for its extensive system that is partially open for tours. Salt Pond is home of the Long Island Regatta, an event that draws tourists from around the world
4.
Geology
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Geology is an earth science concerned with the solid Earth, the rocks of which it is composed, and the processes by which they change over time. Geology can also refer generally to the study of the features of any terrestrial planet. Geology gives insight into the history of the Earth by providing the evidence for plate tectonics, the evolutionary history of life. Geology also plays a role in engineering and is a major academic discipline. The majority of data comes from research on solid Earth materials. These typically fall into one of two categories, rock and unconsolidated material, the majority of research in geology is associated with the study of rock, as rock provides the primary record of the majority of the geologic history of the Earth. There are three types of rock, igneous, sedimentary, and metamorphic. The rock cycle is an important concept in geology which illustrates the relationships between three types of rock, and magma. When a rock crystallizes from melt, it is an igneous rock, the sedimentary rock can then be subsequently turned into a metamorphic rock due to heat and pressure and is then weathered, eroded, deposited, and lithified, ultimately becoming a sedimentary rock. Sedimentary rock may also be re-eroded and redeposited, and metamorphic rock may also undergo additional metamorphism, all three types of rocks may be re-melted, when this happens, a new magma is formed, from which an igneous rock may once again crystallize. Geologists also study unlithified material which typically comes from more recent deposits and these materials are superficial deposits which lie above the bedrock. Because of this, the study of material is often known as Quaternary geology. This includes the study of sediment and soils, including studies in geomorphology, sedimentology and this theory is supported by several types of observations, including seafloor spreading, and the global distribution of mountain terrain and seismicity. This coupling between rigid plates moving on the surface of the Earth and the mantle is called plate tectonics. The development of plate tectonics provided a basis for many observations of the solid Earth. Long linear regions of geologic features could be explained as plate boundaries, mid-ocean ridges, high regions on the seafloor where hydrothermal vents and volcanoes exist, were explained as divergent boundaries, where two plates move apart. Arcs of volcanoes and earthquakes were explained as convergent boundaries, where one plate subducts under another, transform boundaries, such as the San Andreas Fault system, resulted in widespread powerful earthquakes. Plate tectonics also provided a mechanism for Alfred Wegeners theory of continental drift and they also provided a driving force for crustal deformation, and a new setting for the observations of structural geology
5.
Geologist
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A geologist is a scientist who studies the solid and liquid matter that constitutes the Earth as well as the processes that shape it. Geologists usually study geology, although backgrounds in physics, chemistry, biology, field work is an important component of geology, although many subdisciplines incorporate laboratory work. Some geologists work in the mining business searching for metals, oils and they are also in the forefront of natural hazards and disasters prevention and mitigation, studying natural hazards such as earthquakes, volcanic activity, tsunamis, weather storms. Their studies are used to warn the public of the occurrence of these events. Geologists are also important contributors to climate change discussions, james Hutton is often viewed as the first modern geologist. In 1785 he presented a paper entitled Theory of the Earth to the Royal Society of Edinburgh, Hutton published a two-volume version of his ideas in 1795. The first geological map of the U. S. was produced in 1809 by William Maclure, in 1807, Maclure commenced the self-imposed task of making a geological survey of the United States. Almost every state in the Union was traversed and mapped by him and this antedates William Smiths geological map of England by six years, although it was constructed using a different classification of rocks. Sir Charles Lyell first published his famous book, Principles of Geology and this book, which influenced the thought of Charles Darwin, successfully promoted the doctrine of uniformitarianism. This theory states that slow geological processes have occurred throughout the Earths history and are still occurring today, in contrast, catastrophism is the theory that Earths features formed in single, catastrophic events and remained unchanged thereafter. Though Hutton believed in uniformitarianism, the idea was not widely accepted at the time, most geologists also need skills in GIS and other mapping techniques. Geology students often spend portions of the year, especially the summer though sometimes during a January term, geologists may concentrate their studies or research in one or more of the following disciplines, Dendrochronology, the study of dating based on tree ring patterns. Economic geology, the study of ore genesis, and the mechanisms of ore creation, geochemistry, the applied branch deals with the study of the chemical makeup and behaviour of rocks, and the study of the behaviour of their minerals. Geochronology, the study of isotope geology specifically toward determining the date within the past of rock formation, metamorphism, mineralization and geological events. Geomorphology, the study of landforms and the processes that create them Hydrogeology, igneous petrology, the study of igneous processes such as igneous differentiation, fractional crystallization, intrusive and volcanological phenomena. Isotope geology, the case of the composition of rocks to determine the processes of rock. Metamorphic petrology, the study of the effects of metamorphism on minerals, marine geology, the study of the seafloor, involves geophysical, geochemical, sedimentological and paleontological investigations of the ocean floor and coastal margins. Marine geology has strong ties to physical oceanography and plate tectonics, palaeoclimatology, the application of geological science to determine the climatic conditions present in the Earths atmosphere within the Earths history
6.
Amanz Gressly
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Amanz Gressly was a Swiss geologist and paleontologist. He introduced the use of the term facies in geology, he is considered one of the founders of modern stratigraphy and he initially studied medicine at Strasbourg, but his interest subsequently switched to geology, and from 1836 onward, he worked as an assistant to Louis Agassiz. From 1853 he served as a geologist during the construction of tunnels through the Jura Mountains. Since 2004 the Swiss Paleontological Society has awarded the Amanz-Gressly-Auszeichnung for outstanding achievements in the field of paleontology, in, Gallerie berühmter Schweizer der Neuzeit, Bd.1. Hugo Ledermann, Die wissenschaftliche Bedeutung von Amanz Gressly, hans R. Stampfli, Amanz Gressly, 1814-1865, Lebensbild eines außerordentlichen Menschen. Separatdruck aus, Mitteilungen der Naturforschenden Gesellschaft des Kantons Solothurn,32, dazu erschienen, Ergänzungen und Korrekturen,1993
7.
Stratigraphy
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Stratigraphy is a branch of geology which studies rock layers and layering. It is primarily used in the study of sedimentary and layered volcanic rocks, stratigraphy has two related subfields, lithologic stratigraphy or lithostratigraphy, and biologic stratigraphy or biostratigraphy. The first practical application of stratigraphy was by William Smith in the 1790s. Another influential application of stratigraphy in the early 19th century was a study by Georges Cuvier, variation in rock units, most obviously displayed as visible layering, is due to physical contrasts in rock type. This variation can occur vertically as layering, or laterally, and these variations provide a lithostratigraphy or lithologic stratigraphy of the rock unit. Key concepts in stratigraphy involve understanding how certain geometric relationships between rock layers arise and what these geometries imply about their original depositional environment. The basic concept in stratigraphy, called the law of superposition, states, in a stratigraphic sequence. Chemostratigraphy studies the changes in the proportions of trace elements and isotopes within. Carbon and oxygen isotope ratios vary with time, and researchers can use those to map subtle changes that occurred in the paleoenvironment and this has led to the specialized field of isotopic stratigraphy. Biostratigraphy or paleontologic stratigraphy is based on evidence in the rock layers. Strata from widespread locations containing the fossil fauna and flora are said to be correlatable in time. Biologic stratigraphy was based on William Smiths principle of succession, which predated. It provides strong evidence for the formation and extinction of species, the geologic time scale was developed during the 19th century, based on the evidence of biologic stratigraphy and faunal succession. One important development is the Vail curve, which attempts to define a global historical sea-level curve according to inferences from worldwide stratigraphic patterns, stratigraphy is also commonly used to delineate the nature and extent of hydrocarbon-bearing reservoir rocks, seals, and traps of petroleum geology. Chronostratigraphy is the branch of stratigraphy that places an absolute age, a gap or missing strata in the geological record of an area is called a stratigraphic hiatus. This may be the result of a halt in the deposition of sediment, alternatively, the gap may be due to removal by erosion, in which case it may be called a stratigraphic vacuity. It is called a hiatus because deposition was on hold for a period of time, a physical gap may represent both a period of non-deposition and a period of erosion. A geologic fault may cause the appearance of a hiatus, magnetostratigraphy is a chronostratigraphic technique used to date sedimentary and volcanic sequences
8.
Neptunism
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Neptunism, a superseded scientific theory of geology proposed by Abraham Gottlob Werner in the late 18th century, proposed rocks formed from the crystallisation of minerals in the early Earths oceans. The theory took its name from Neptune, the ancient Roman god of the sea, Modern geology acknowledges many different forms of rock formation, and explains the formation of sedimentary rock through processes very similar to those described by neptunism. In the mid-eighteenth century as the investigation of geology found evidence such as fossils, georges de Buffon proposed that the Earth was over 75,000 years old, possibly much older, and showed signs of historical development in a series of distinct epochs. Abraham Gottlob Werner was the inspector of mines and professor of mining and he based his historical sequence of rock formation on the theory that the Earth had originally consisted of water. There is no indication that any of the floods in Werners cosmogony were Noahs flood, a rival theory known as plutonism held that rocks were formed in fire. Neptunists differed from the plutonists in holding that basalt was a deposit which included fossils. Hutton correctly asserted that basalt never contained fossils and was always insoluble, hard and he found geological formations in which basalt cut through layers of other rocks, supporting his theory that it originated from molten rock under the Earths crust. The debate was not just between scientists, johann Wolfgang von Goethe, one of the most respected authors of the day, took sides with the neptunists. The fourth act of his famous work Faust contains a dialogue between a neptunist and a plutonist, the latter being Mephistopheles, the antagonist of the play who is a devil. Doing so he expressed his favour for the neptunist theory, though he also did so explicitly. The controversy lasted into the years of the 19th century, but the works of Charles Lyell in the 1830s gradually won over support for the uniformitarian ideas of Hutton. Gustav Bischof, founder of geochemistry, introduced chemical analysis into widespread use in geology, the theory, and its intellectual context, are treated with engaging irony in Daniel Kehlmanns fictionalised account of the travels of Alexander von Humboldt, Die Vermessung der Welt of 2006. Erickson, Jon, Plate Tectonics, New York, Facts On File,1992 Baigrie, Brian, Scientific Revolutions, Course Notes and Study Material, History of Science, Early Modern Geology. And Still We Evolve, A Handbook on the History of Modern Science, Ian Johnston of Malaspina University-College, Nanaimo, BC
9.
Triassic
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The Triassic is a geologic period and system which spans 50.9 million years from the end of the Permian Period 252.17 million years ago, to the beginning of the Jurassic Period 201.3 Mya. The Triassic is the first period of the Mesozoic Era, both the start and end of the period are marked by major extinction events. Therapsids and archosaurs were the terrestrial vertebrates during this time. A specialized subgroup of archosaurs, called dinosaurs, first appeared in the Late Triassic, the vast supercontinent of Pangaea existed until the mid-Triassic, after which it began to gradually rift into two separate landmasses, Laurasia to the north and Gondwana to the south. The global climate during the Triassic was mostly hot and dry, however, the climate shifted and became more humid as Pangaea began to drift apart. The end of the period was marked by yet another mass extinction, the Triassic-Jurassic extinction event. The Triassic is usually separated into Early, Middle, and Late Triassic Epochs, from the east, along the equator, the Tethys sea penetrated Pangaea, causing the Paleo-Tethys Ocean to be closed. Later in the mid-Triassic a similar sea penetrated along the equator from the west, the remaining shores were surrounded by the world-ocean known as Panthalassa. All the deep-ocean sediments laid down during the Triassic have disappeared through subduction of oceanic plates, thus, the supercontinent Pangaea was rifting during the Triassic—especially late in that period—but had not yet separated. In North America, for example, marine deposits are limited to a few exposures in the west, thus Triassic stratigraphy is mostly based on organisms that lived in lagoons and hypersaline environments, such as Estheria crustaceans. At the beginning of the Mesozoic Era, Africa was joined with Earths other continents in Pangaea, Africa shared the supercontinents relatively uniform fauna which was dominated by theropods, prosauropods and primitive ornithischians by the close of the Triassic period. Late Triassic fossils are found throughout Africa, but are common in the south than north. The time boundary separating the Permian and Triassic marks the advent of an event with global impact. At Paleorrota geopark, located in Rio Grande do Sul, Brazil, in these formations, one of the earliest dinosaurs, Staurikosaurus, as well as the mammal ancestors Brasilitherium and Brasilodon have been discovered. The Triassic continental interior climate was hot and dry, so that typical deposits are red bed sandstones and evaporites. Pangaeas large size limited the effect of the global ocean, its continental climate was highly seasonal, with very hot summers. The strong contrast between the Pangea supercontinent and the global ocean triggered intense cross-equatorial monsoons, the best studied of such episodes of humid climate, and probably the most intense and widespread, was the Carnian Pluvial Event. On land, the vascular plants included the lycophytes, the dominant cycadophytes, ginkgophyta, ferns, horsetails
10.
Utah
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Utah is a state in the western United States. It became the 45th state admitted to the U. S. on January 4,1896, Utah is the 13th-largest by area, 31st-most-populous, and 10th-least-densely populated of the 50 United States. Utah has a population of more than 3 million, approximately 80% of whom live along the Wasatch Front, Utah is bordered by Colorado to the east, Wyoming to the northeast, Idaho to the north, Arizona to the south, and Nevada to the west. It also touches a corner of New Mexico in the southeast, approximately 62% of Utahns are reported to be members of The Church of Jesus Christ of Latter-day Saints or LDS, which greatly influences Utahn culture and daily life. The LDS Churchs world headquarters is located in Salt Lake City, Utah is the only state with a majority population belonging to a single church. The state is a center of transportation, education, information technology and research, government services, mining, in 2013, the U. S. Census Bureau estimated that Utah had the second fastest-growing population of any state. St. George was the metropolitan area in the United States from 2000 to 2005. Utah also has the 14th highest median income and the least income inequality of any U. S. state. A2012 Gallup national survey found Utah overall to be the best state to live in based on 13 forward-looking measurements including various economic, lifestyle, the name Utah is derived from the name of the Ute tribe. It means people of the mountains in the Ute language, according to other sources Utah is derived from the Apache name Yudah which means Tall. These Native American tribes are subgroups of the Ute-Aztec Native American ethnicity and were sedentary, the Ancestral Pueblo people built their homes through excavations in mountains, and the Fremont people built houses of straw before disappearing from the region around the 15th century. Another group of Native Americans, the Navajo, settled in the region around the 18th century, in the mid-18th century, other Uto-Aztecan tribes, including the Goshute, the Paiute, the Shoshone, and the Ute people, also settled in the region. These five groups were present when the first European explorers arrived, the southern Utah region was explored by the Spanish in 1540, led by Francisco Vásquez de Coronado, while looking for the legendary Cíbola. A group led by two Catholic priests—sometimes called the Dominguez-Escalante Expedition—left Santa Fe in 1776, hoping to find a route to the coast of California, the expedition traveled as far north as Utah Lake and encountered the native residents. The Spanish made further explorations in the region, but were not interested in colonizing the area because of its desert nature, in 1821, the year Mexico achieved its independence from Spain, the region became known as part of its territory of Alta California. European trappers and fur traders explored some areas of Utah in the early 19th century from Canada, the city of Provo, Utah was named for one, Étienne Provost, who visited the area in 1825. The city of Ogden, Utah was named after Peter Skene Ogden, in late 1824, Jim Bridger became the first known English-speaking person to sight the Great Salt Lake. Due to the salinity of its waters, Bridger thought he had found the Pacific Ocean
11.
Sedimentary structures
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Sedimentary structures are those structures formed during sediment deposition. There are two kinds of structures, bidirectional and unidirectional. Flow regimes in single-direction flow, which at varying speeds and velocities produce different structures, are called bedforms, in the lower flow regime, the natural progression is from a flat bed, to some sediment movement, to ripples, to slightly larger dunes. Dunes have a vortex in the lee side of the dune, as the upper flow regime forms, the dunes become flattened out, and then produce antidunes. At higher still velocity, the antidunes are flattened and most sedimentation stops, ripple marks usually form in conditions with flowing water, in the lower part of the Lower Flow Regime. There are two types of marks, Symmetrical ripple marks - Often found on beaches, they are created by a two way current, for example the waves on a beach. This creates ripple marks with pointed crests and rounded troughs, which arent inclined more to a certain direction, three common sedimentary structures that are created by these processes are herringbone cross-stratification, flaser bedding, and interference ripples. Asymmetrical ripple marks - These are created by a one way current, for example in a river and this creates ripple marks with still pointed crests and rounded troughs, but which are inclined more strongly in the direction of the current. For this reason, they can be used as palaeocurrent indicators, antidunes are the sediment bedforms created by fast, shallow flows of water with a Froude number greater than 1. Antidunes form beneath standing waves of water that periodically steepen, migrate, the antidune bedform is characterized by shallow foresets, which dip upstream at an angle of about ten degrees that can be up to five meters in length. They can be identified by their low angle foresets, for the most part, antidunes bedforms are destroyed during decreased flow, and therefore cross bedding formed by antidunes will not be preserved. A number of biologically-created sedimentary structures exist, called trace fossils, examples include burrows and various expressions of bioturbation. Ichnofacies are groups of fossils that together help give information on the depositional environment. In general, as deeper burrows become more common, the shallower the water, as surface traces become more common, the water becomes deeper. Microbes may also interact with sediment to form Microbially Induced Sedimentary Structures, soft-sediment deformation structures or SSD, is a consequence of the loading of wet sediment as burial continues after deposition. The heavier sediment squeezes the water out of the sediment due to its own weight. There are three variants of SSD, load structures or load casts are blobs that form when a denser, wet sediment slumps down on. Pseudonodules or ball-and-pillow structures, are pinched-off load structures, these may also be formed by earthquake energy, flame structures, fingers of mud that protrude into overlying sediments
12.
Stratigraphic unit
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Units must be mappable and distinct from one another, but the contact need not be particularly distinct. For instance, a unit may be defined by such as when the sandstone component exceeds 75%. Sequences of sedimentary and volcanic rocks are subdivided on the basis of their lithology, going from smaller to larger in scale, the main units recognised are Bed, Member, Formation, Group and Supergroup. A bed is a distinct layer within a member or formation and is the smallest recognisable stratigraphic unit. These are not normally named, but may be in the case of a marker horizon, a member is a named lithologically distinct part of a formation. Not all formations are subdivided in this way and even where they are recognized, formations are the primary units used in the subdivision of a sequence and may vary in scale from tens of centimetres to kilometres. They should be distinct lithologically from other formations, although the boundaries do not need to be sharp, to be formally recognised, a formation must have sufficient extent to be useful in mapping an area. A group is a set of two or more formations that share certain lithological characteristics, a group may be made up of different formations in different geographical areas and individual formations may appear in more than one group. A supergroup is a set of two or more associated groups and/or formations that share certain lithological characteristics, a supergroup may be made up of different groups in different geographical areas. A sequence of fossil-bearing sedimentary rocks can be subdivided on the basis of the occurrence of fossil taxa. A unit defined in this way is known as a biostratigraphic unit, the five commonly used types of biozone are assemblage, range, abundance, interval and lineage zones. An assemblage zone is a stratigraphic interval characterised by an assemblage of three or more coexisting fossil taxa that distinguish it from surrounding strata. A range zone is an interval that represents the occurrence range of a specific fossil taxon. An abundance zone is an interval in which the abundance of a particular taxon is significantly greater than seen in neighbouring parts of the succession. An interval zone is a stratigraphic interval whose top and base are defined by horizons that mark the first or last occurrence of two different taxa, a lineage zone is a stratigraphic interval that contains fossils that represent parts of the evolutionary lineage of a particular fossil group. This is a case of a range zone. Chronostratigraphy Glaciology Magnetostratigraphy Sedimentology Sequence stratigraphy Stratigraphy International Commission on Stratigraphy Stratigraphic Guide
13.
Sedimentation
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Sedimentation is the tendency for particles in suspension to settle out of the fluid in which they are entrained and come to rest against a barrier. This is due to their motion through the fluid in response to the acting on them. In geology, sedimentation is often used as the opposite of erosion, in that sense, it includes the termination of transport by saltation or true bedload transport. Settling is the falling of suspended particles through the liquid, whereas sedimentation is the termination of the settling process, in estuarine environments, settling can be influenced by the presence or absence of vegetation. Trees such as mangroves are crucial to the attenuation of waves or currents, even small molecules supply a sufficiently strong force to produce significant sedimentation. This process is used in the biotech industry to separate cells from the culture media. In a sedimentation experiment, the applied force accelerates the particles to a velocity v t e r m at which the applied force is exactly canceled by an opposing drag force. For small enough particles, the force varies linearly with the terminal velocity, i. e. F d r a g = f v t e r m where f depends only on the properties of the particle. Thus, measuring s can reveal underlying properties of the particle, in many cases, the motion of the particles is blocked by a hard boundary, the resulting accumulation of particles at the boundary is called a sediment. The concentration of particles at the boundary is opposed by the diffusion of the particles, the sedimentation of a single particle under gravity is described by the Mason–Weaver equation, which has a simple exact solution. The sedimentation coefficient s in this case equals m b / f, the sedimentation of a single particle under centrifugal force is described by the Lamm equation, which likewise has an exact solution. The sedimentation coefficient s also equals m b / f, where m b is the buoyant mass, the Lamm equation also has extra terms, since it pertains to sector-shaped cells, whereas the Mason–Weaver equation is one-dimensional. They settle as individual particles and do not flocculate or stick to other during settling, example, alum or iron coagulation Type 3 sedimentation is also known as zone sedimentation. In this process the particles are at a high concentration such that the particles tend to settle as a mass, zone settling occurs in lime-softening, sedimentation, active sludge sedimentation and sludge thickeners. In geology, sedimentation is the deposition of particles carried by a fluid flow, for suspended load, this can be expressed mathematically by the Exner equation, and results in the formation of depositional landforms and the rocks that constitute sedimentary record. An undesired increased transport and sedimentation of suspended material is called siltation, high sedimentation rates can be a result of poor land management and a high frequency of flooding events. If not managed properly, it can be detrimental to fragile ecosystems on the receiving end, climate change also affects siltation rates. In chemistry, sedimentation has been used to measure the size of large molecules, where the force of gravity is augmented with centrifugal force in an ultracentrifuge
14.
Aspect (geography)
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In physical geology, aspect is the compass direction that a slope faces. For example, a slope on the edge of the Rockies toward the Great Plains is described as having an easterly aspect. A slope which falls down to a valley on its western side. The direction a slope faces can affect the physical and biotic features of the slope, the term aspect can also be used to describe the shape or alignment of a coastline. Here, the aspect is the direction which the coastline is facing towards the sea, for example, a coastline with sea to the northeast has a northeasterly aspect. Aspect can have an influence on temperature. This is because of the angle of the sun in the northern and southern hemispheres which is less than 90 degrees or directly overhead. 5° at 40° north on December 22, the aspect of a slope can make very significant influences on its local climate. For example, because the rays are in the west at the hottest time of day in the afternoon. This can have effects on altitudinal and polar limits of tree growth. In Australia, for example, remnants of rainforest are almost always found on east-facing slopes which are protected from dry westerly wind, similarly, in the northern hemisphere a south-facing slope will therefore generally be warmer and dryer due to higher levels of evapotranspiration than a north-facing slope. This can be seen in the Swiss Alps, where farming is more extensive on south-facing than on north-facing slopes. In the Himalayas, this effect can be seen to a degree, with south-facing slopes being warm, wet and forested. In some locales there are patterns of soil differences related to differences in aspect, aspect similarly influence seasonal soil biological processes that are temperature dependent. Particulate laden winds often blow from a prevailing direction near solar early afternoon, the summer dryness of the Coromandel Coast due to the southerly monsoon flowing parallel to the coast. Its wetness during the northeast monsoon is similarly explained, the anomalous late autumn rainy seasons of central Vietnam and the coastal zone of northeastern Brazil for the same reason as above. The unusual dryness of Port Moresby compared to the rest of New Guinea is because the National Capital District lies parallel to the winds which have a drying effect. In Gulf Province and Lae, which receives their full force, rainfall during winter is exceedingly heavy, with rainfall. The relative dryness of the Queensland coast has the same cause as with Port Moresby
15.
Petrology
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Petrology is the branch of geology that studies the origin, composition, distribution and structure of rocks. In the petroleum industry, lithology, or more specifically mud logging, is the representation of geological formations being drilled through. As the cuttings are circulated out of the borehole they are sampled, examined and tested chemically when needed, Petrology utilizes the fields of mineralogy, petrography, optical mineralogy, and chemical analysis to describe the composition and texture of rocks. Igneous rocks include volcanic and plutonic rocks, sedimentary petrology focuses on the composition and texture of sedimentary rocks. Experiments are particularly useful for investigating rocks of the lower crust and they are also one of the prime sources of information about completely inaccessible rocks such as those in the Earths lower mantle and in the mantles of the other terrestrial planets and the Moon. The work of experimental petrologists has laid a foundation on which modern understanding of igneous, important publications in petrology Ore Soil Best, Myron G. Igneous and Metamorphic Petrology. ISBN 1-4051-0588-7 Blatt, Harvey, Tracy, Robert J. Owens, Brent, Petrology, igneous, sedimentary, ISBN 978-0-7167-3743-8 Dietrich, Richard Vincent, Skinner, Brian J. Gems, Granites, and Gravels, knowing and using rocks and minerals. ISBN 978-0-521-10722-8 Fei, Yingwei, Bertka, Constance M. Mysen, mantle Petrology, field observations and high-pressure experimentation. ISBN 0-941809-05-6 Philpotts, Anthony, Ague, Jay, Principles of Igneous and Metamorphic Petrology
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Mineralogy
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Mineralogy is a subject of geology specializing in the scientific study of chemistry, crystal structure, and physical properties of minerals and mineralized artifacts. Specific studies within mineralogy include the processes of mineral origin and formation, classification of minerals, their geographical distribution, the German Renaissance specialist Georgius Agricola wrote works such as De re metallica and De Natura Fossilium which began the scientific approach to the subject. Systematic scientific studies of minerals and rocks developed in post-Renaissance Europe, the modern study of mineralogy was founded on the principles of crystallography and to the microscopic study of rock sections with the invention of the microscope in the 17th century. Nicholas Steno first observed the law of constancy of interfacial angles in quartz crystals in 1669 and this was later generalized and established experimentally by Jean-Baptiste L. Romé de lIslee in 1783. In 1814, Jöns Jacob Berzelius introduced a classification of minerals based on their chemistry rather than their crystal structure, james D. Dana published his first edition of A System of Mineralogy in 1837, and in a later edition introduced a chemical classification that is still the standard. It, however, retains a focus on the structures commonly encountered in rock-forming minerals. An initial step in identifying a mineral is to examine its physical properties and these can be classified into density, measures of mechanical cohesion, macroscopic visual properties, magnetic and electric properties, radioactivity and solubility in hydrogen chloride. If the mineral is crystallized, it will also have a distinctive crystal habit that reflects the crystal structure or internal arrangement of atoms. It is also affected by crystal defects and twinning. Many crystals are polymorphic, having more than one crystal structure depending on factors such as pressure and temperature. ”Examples of polymorphs are calcite and aragonite - two minerals with identical chemical composition, distinguished by their crystallography, calcite is rhombohedral and aragonite is orthorhombic. The crystal structure is the arrangement of atoms in a crystal and it is represented by a lattice of points which repeats a basic pattern, called a unit cell, in three dimensions. The lattice can be characterized by its symmetries and by the dimensions of the unit cell and these dimensions are represented by three Miller indices. The lattice remains unchanged by certain symmetry operations about any point in the lattice, reflection, rotation, inversion, and rotary inversion. Together, they make up an object called a crystallographic point group or crystal class. There are 32 possible crystal classes, in addition, there are operations that displace all the points, translation, screw axis, and glide plane. In combination with the point symmetries, they form 230 possible space groups, most geology departments have X-ray powder diffraction equipment to analyze the crystal structures of minerals. X-rays have wavelengths that are the order of magnitude as the distances between atoms. In a sample that is ground to a powder, the X-rays sample a random distribution of all crystal orientations, powder diffraction can distinguish between minerals that may appear the same in a hand sample, for example quartz and its polymorphs tridymite and cristobalite
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Lithology
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It may be either a detailed description of these characteristics or be a summary of the gross physical character of a rock. It is the basis of subdividing rock sequences into individual lithostratigraphic units for the purposes of mapping, in certain applications, such as site investigations, lithology is described using a standard terminology such as in the European geotechnical standard Eurocode 7. The naming of a lithology is based on the rock type, the three major rock types are sedimentary, igneous, metamorphic. Sedimentary rocks are classified by whether they are siliciclastic or carbonate. Siliciclastic sedimentary rocks are then subcategorized based on their size distribution and the relative proportions of quartz, feldspar. Carbonate rocks are classified with the Dunham or Folk classification schemes according to the constituents of the carbonate rock, the name of an igneous rock requires information on crystal size and mineralogy. This classification can often be performed with a QAPF diagram, metamorphic rock naming can be based on texture, protolith, metamorphic facies, and/or the locations in which they are found. Naming based on texture and a pelite protolith can be used to slate and phyllite. Texture-based names are schist and gneiss and these textures, from slate to gneiss, define a continually-increasing extent of metamorphism. Metamorphic facies are defined by the fields in which particular minerals form. In igneous and metamorphic rocks, grain size is a measure of the sizes of the crystals in the rock. In igneous rock, this is used to determine the rate at which the material cooled, large crystals typically indicate intrusive igneous rock, as metamorphic reactions progress, the grains in metamorphic rocks can often be broken down into smaller grains. In clastic sedimentary rocks, grain size is the diameter of the grains and/or clasts that constitute the rock and these are used to determine which rock naming system to use. In the case of sandstones and conglomerates, which cover a range of grain sizes. Examples are pebble conglomerate and fine quartz arenite, in rocks in which mineral grains are large enough to be identified using a hand lens, the visible mineralogy is included as part of the description. The mineralogical composition of a rock is one of the ways in which it is classified. In general, igneous rocks can be categorized by increasing silica content as ultramafic, mafic, intermediate, or felsic, the fabric of a rock describes the spatial and geometric configuration of all the elements that make it up. In sedimentary rocks the main fabric is normally bedding and the scale
18.
Paleontology
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Paleontology or palaeontology is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene Epoch. It includes the study of fossils to determine organisms evolution and interactions with each other, paleontological observations have been documented as far back as the 5th century BC. The science became established in the 18th century as a result of Georges Cuviers work on comparative anatomy, and developed rapidly in the 19th century. The term itself originates from Greek παλαιός, palaios, i. e. old, ancient, ὄν, on, i. e. being, creature and λόγος, logos, i. e. speech, thought, study. Paleontology lies on the border between biology and geology, but differs from archaeology in that it excludes the study of modern humans. It now uses techniques drawn from a range of sciences, including biochemistry, mathematics. The final quarter of the 20th century saw the development of molecular phylogenetics, molecular phylogenetics has also been used to estimate the dates when species diverged, but there is controversy about the reliability of the molecular clock on which such estimates depend. The simplest definition is the study of ancient life, paleontology is one of the historical sciences, along with archaeology, geology, astronomy, cosmology, philology and history itself. This means that it aims to describe phenomena of the past, hence it has three main elements, description of the phenomena, developing a general theory about the causes of various types of change, and applying those theories to specific facts. Sometimes the smoking gun is discovered by an accident during other research. Paleontology lies on the boundary between biology and geology since paleontology focuses on the record of past life but its source of evidence is fossils. In addition paleontology often uses techniques derived from other sciences, including biology, osteology, ecology, chemistry, techniques developed in engineering have been used to analyse how ancient organisms might have worked, for example how fast Tyrannosaurus could move and how powerful its bite was. As knowledge has increased, paleontology has developed specialised subdivisions, vertebrate paleontology concentrates on fossils of vertebrates, from the earliest fish to the immediate ancestors of modern mammals. Invertebrate paleontology deals with fossils of such as molluscs, arthropods. Paleobotany focuses on the study of plants, but traditionally includes the study of fossil algae. Palynology, the study of pollen and spores produced by plants and protists. Micropaleontology deals with all microscopic fossil organisms, regardless of the group to which they belong, one example is the development of oxygenic photosynthesis by bacteria, which hugely increased the productivity and diversity of ecosystems. This also caused the oxygenation of the atmosphere, together, these were a prerequisite for the evolution of the most complex eukaryotic cells, from which all multicellular organisms are built
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Limestone
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Limestone is a sedimentary rock, composed mainly of skeletal fragments of marine organisms such as coral, forams and molluscs. Its major materials are the minerals calcite and aragonite, which are different crystal forms of calcium carbonate, about 10% of sedimentary rocks are limestones. The solubility of limestone in water and weak acid solutions leads to karst landscapes, most cave systems are through limestone bedrock. The first geologist to distinguish limestone from dolomite was Belsazar Hacquet in 1778, like most other sedimentary rocks, most limestone is composed of grains. Most grains in limestone are skeletal fragments of organisms such as coral or foraminifera. Other carbonate grains comprising limestones are ooids, peloids, intraclasts and these organisms secrete shells made of aragonite or calcite, and leave these shells behind when they die. Limestone often contains variable amounts of silica in the form of chert or siliceous skeletal fragment, some limestones do not consist of grains at all, and are formed completely by the chemical precipitation of calcite or aragonite, i. e. travertine. Secondary calcite may be deposited by supersaturated meteoric waters and this produces speleothems, such as stalagmites and stalactites. Another form taken by calcite is oolitic limestone, which can be recognized by its granular appearance, the primary source of the calcite in limestone is most commonly marine organisms. Some of these organisms can construct mounds of rock known as reefs, below about 3,000 meters, water pressure and temperature conditions cause the dissolution of calcite to increase nonlinearly, so limestone typically does not form in deeper waters. Limestones may also form in lacustrine and evaporite depositional environments, calcite can be dissolved or precipitated by groundwater, depending on several factors, including the water temperature, pH, and dissolved ion concentrations. Calcite exhibits a characteristic called retrograde solubility, in which it becomes less soluble in water as the temperature increases. Impurities will cause limestones to exhibit different colors, especially with weathered surfaces, Limestone may be crystalline, clastic, granular, or massive, depending on the method of formation. Crystals of calcite, quartz, dolomite or barite may line small cavities in the rock, when conditions are right for precipitation, calcite forms mineral coatings that cement the existing rock grains together, or it can fill fractures. Travertine is a banded, compact variety of limestone formed along streams, particularly there are waterfalls. Calcium carbonate is deposited where evaporation of the leaves a solution supersaturated with the chemical constituents of calcite. Tufa, a porous or cellular variety of travertine, is found near waterfalls, coquina is a poorly consolidated limestone composed of pieces of coral or shells. During regional metamorphism that occurs during the building process, limestone recrystallizes into marble
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Shale
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Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable, shale is characterized by breaks along thin laminae or parallel layering or bedding less than one centimeter in thickness, called fissility. Mudstones, on the hand, are similar in composition. Before the mid 19th century, the slate, shale. In the context of underground mining, shale was frequently referred to as slate well into the 20th century. Non-fissile rocks of similar composition but made of smaller than 0.06 mm are described as mudstones or claystone. Rocks with similar sizes but with less clay and therefore grittier are siltstones. Shale is the most common sedimentary rock, shales are typically composed of variable amounts of clay minerals and quartz grains and the typical color is gray. Addition of variable amounts of minor constituents alters the color of the rock, black shale results from the presence of greater than one percent carbonaceous material and indicates a reducing environment. Black shale can also be referred to as black metal, red, brown and green colors are indicative of ferric oxide, iron hydroxide, or micaceous minerals. Clays are the constituent of shales and other mudrocks. The clay minerals represented are largely kaolinite, montmorillonite and illite, clay minerals of Late Tertiary mudstones are expandable smectites whereas in older rocks especially in mid- to early Paleozoic shales illites predominate. The transformation of smectite to illite produces silica, sodium, calcium, magnesium, iron and these released elements form authigenic quartz, chert, calcite, dolomite, ankerite, hematite and albite, all trace to minor minerals found in shales and other mudrocks. Shales and mudrocks contain roughly 95 percent of the matter in all sedimentary rocks. However, this amounts to less than one percent by mass in an average shale, black shales, which form in anoxic conditions, contain reduced free carbon along with ferrous iron and sulfur. Pyrite and amorphous iron sulfide along with carbon produce the black coloration, the process in the rock cycle which forms shale is called compaction. The fine particles that compose shale can remain suspended in long after the larger particles of sand have deposited. Shales are typically deposited in very slow moving water and are found in lakes and lagoonal deposits, in river deltas, on floodplains
21.
Rock (geology)
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Rock or stone is a natural substance, a solid aggregate of one or more minerals or mineraloids. For example, granite, a rock, is a combination of the minerals quartz, feldspar. The Earths outer solid layer, the lithosphere, is made of rock, rock has been used by mankind throughout history. The minerals and metals found in rocks have been essential to human civilization, three major groups of rocks are defined, igneous, sedimentary, and metamorphic. The scientific study of rocks is called petrology, which is a component of geology. At a granular level, rocks are composed of grains of minerals, the aggregate minerals forming the rock are held together by chemical bonds. The types and abundance of minerals in a rock are determined by the manner in which the rock was formed, many rocks contain silica, a compound of silicon and oxygen that forms 74. 3% of the Earths crust. This material forms crystals with other compounds in the rock, the proportion of silica in rocks and minerals is a major factor in determining their name and properties. Rocks are geologically classified according to such as mineral and chemical composition, permeability, the texture of the constituent particles. These physical properties are the end result of the processes that formed the rocks, over the course of time, rocks can transform from one type into another, as described by the geological model called the rock cycle. These events produce three general classes of rock, igneous, sedimentary, and metamorphic, the three classes of rocks are subdivided into many groups. However, there are no hard and fast boundaries between allied rocks, hence the definitions adopted in establishing rock nomenclature merely correspond to more or less arbitrary selected points in a continuously graduated series. Igneous rock forms through the cooling and solidification of magma or lava and this magma can be derived from partial melts of pre-existing rocks in either a planets mantle or crust. Typically, the melting of rocks is caused by one or more of three processes, an increase in temperature, a decrease in pressure, or a change in composition, igneous rocks are divided into two main categories, plutonic rock and volcanic. Plutonic or intrusive rocks result when magma cools and crystallizes slowly within the Earths crust, a common example of this type is granite. Volcanic or extrusive rocks result from magma reaching the surface either as lava or fragmental ejecta, the chemical abundance and the rate of cooling of magma typically forms a sequence known as Bowens reaction series. Most major igneous rocks are found along this scale, about 64. 7% of the Earths crust by volume consists of igneous rocks, making it the most plentiful category. Of these, 66% are basalts and gabbros, 16% are granite, only 0. 6% are syenites and 0. 3% peridotites and dunites
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Depositional environment
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In most cases the environments associated with particular rock types or associations of rock types can be matched to existing analogues. However, the back in geological time sediments were deposited. Sedimentary Environments, Processes, Facies and Stratigraphy, sedimentary Environments Classification Charts Depositional environments on e-notes
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Sedimentary
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Sedimentary rocks are types of rock that are formed by the deposition and subsequent cementation of that material at the Earths surface and within bodies of water. Sedimentation is the name for processes that cause mineral and/or organic particles to settle in place. The particles that form a rock by accumulating are called sediment. Sedimentation may also occur as minerals precipitate from solution or shells of aquatic creatures settle out of suspension. The sedimentary rock cover of the continents of the Earths crust is extensive, sedimentary rocks are only a thin veneer over a crust consisting mainly of igneous and metamorphic rocks. Sedimentary rocks are deposited in layers as strata, forming a structure called bedding, sedimentary rocks are also important sources of natural resources like coal, fossil fuels, drinking water or ores. The study of the sequence of rock strata is the main source for an understanding of the Earths history, including palaeogeography, paleoclimatology. The scientific discipline that studies the properties and origin of rocks is called sedimentology. Sedimentology is part of both geology and physical geography and overlaps partly with other disciplines in the Earth sciences, such as pedology, geomorphology, geochemistry, sedimentary rocks have also been found on Mars. Clastic sedimentary rocks are composed of rock fragments that were cemented by silicate minerals. Clastic rocks are composed largely of quartz, feldspar, rock fragments, clay minerals, and mica, any type of mineral may be present, clastic sedimentary rocks, are subdivided according to the dominant particle size. Most geologists use the Udden-Wentworth grain size scale and divide unconsolidated sediment into three fractions, gravel, sand, and mud and this tripartite subdivision is mirrored by the broad categories of rudites, arenites, and lutites, respectively, in older literature. The subdivision of these three categories is based on differences in clast shape, conglomerates and breccias), composition. Conglomerates are dominantly composed of rounded gravel, while breccias are composed of dominantly angular gravel, composition of framework grains The relative abundance of sand-sized framework grains determines the first word in a sandstone name. Naming depends on the dominance of the three most abundant components quartz, feldspar, or the lithic fragments that originated from other rocks, all other minerals are considered accessories and not used in the naming of the rock, regardless of abundance. Clean sandstones with open space are called arenites. Muddy sandstones with abundant muddy matrix are called wackes, six sandstone names are possible using the descriptors for grain composition and the amount of matrix. Mudrocks are sedimentary rocks composed of at least 50% silt- and clay-sized particles and these relatively fine-grained particles are commonly transported by turbulent flow in water or air, and deposited as the flow calms and the particles settle out of suspension
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Palynology
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Palynology is the study of dust or particles that are strewn. A classic palynologist analyses particulate samples collected from the air, from water, the condition and identification of those particles, organic and inorganic, give the palynologist clues to the life, environment, and energetic conditions that produced them. Palynology does not include diatoms, foraminiferans or other organisms with siliceous or calcareous exoskeletons, palynology is an interdisciplinary science and is a branch of earth science and biological science, particularly plant science. Stratigraphical palynology is a branch of micropalaeontology and paleobotany, which studies fossil palynomorphs from the Precambrian to the Holocene, early investigators include Christian Gottfried Ehrenberg, Gideon Mantell and Henry Hopley White. Quantitative analysis of pollen began with Lennart von Posts published work, although he published in the Swedish language, his methodology gained a wide audience through his lectures. In particular, his Kristiania lecture of 1916 was important in gaining a wider audience, because the early investigations published in the Nordic languages or Scandinavian languages the field of pollen analysis was confined to those countries. The isolation ended with the German publication of Gunnar Erdtmans 1921 thesis, the methodology of pollen analysis became widespread throughout Europe and North America and revolutionized Quaternary vegetation and climate change research. Earlier pollen researchers were Früh, who enumerated many common tree types. There is a study of samples taken from sediments of Swedish lakes by Trybom, Pinus. Georg F. L. Sarauw studied fossil pollen of middle Pleistocene age from the harbour of Copenhagen, a. Weber appear to be among the first to undertake percentage frequency calculations. The term palynology was introduced by Hyde and Williams in 1944, following correspondence with the Swedish geologist Antevs, Hyde and Williams chose palynology on the basis of the Greek words paluno meaning to sprinkle and pale meaning dust. Pollen analysis advanced rapidly in this due to advances in optics. Much of the science was revised by Johannes Iversen and Knut Fægri in their textbook on the subject, palynomorphs are broadly defined as organic-walled microfossils between 5 and 500 micrometres in size. They are extracted from sedimentary rocks and sediment cores both physically, by treatment and wet sieving, and chemically, by chemical digestion to remove the non-organic fraction. Palynomorphs may be composed of material such as chitin, pseudochitin and sporopollenin. Palynomorphs that have a taxonomy description are sometimes referred to as palynotaxa, palynomorphs form a geological record of importance in determining the type of prehistoric life that existed at the time the sedimentary formation was laid down. As a result, these microfossils give important clues to the climatic conditions of the time. Their paleontological utility derives from an abundance numbering in millions of cells per gram in organic marine deposits, palynomorphs, however, generally have been destroyed in metamorphic or recrystallized rocks
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Seismology
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Seismology is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other planet-like bodies. A related field that uses geology to infer information regarding past earthquakes is paleoseismology, a recording of earth motion as a function of time is called a seismogram. A seismologist is a scientist who does research in seismology, scholarly interest in earthquakes can be traced back to antiquity. Early speculations on the causes of earthquakes were included in the writings of Thales of Miletus, Anaximenes of Miletus, Aristotle. In 132 CE, Zhang Heng of Chinas Han dynasty designed the first known seismoscope, in 1664, Athanasius Kircher argued that earthquakes were caused by the movement of fire within a system of channels inside the Earth. In 1703, Martin Lister and Nicolas Lemery proposed that earthquakes were caused by chemical explosions within the earth, the Lisbon earthquake of 1755, coinciding with the general flowering of science in Europe, set in motion intensified scientific attempts to understand the behaviour and causation of earthquakes. The earliest responses include work by John Bevis and John Michell, Michell determined that earthquakes originate within the Earth and were waves of movement caused by shifting masses of rock miles below the surface. From 1857, Robert Mallet laid the foundation of instrumental seismology and he is also responsible for coining the word seismology. In 1897, Emil Wiecherts theoretical calculations led him to conclude that the Earths interior consists of a mantle of silicates, surrounding a core of iron. In 1906 Richard Dixon Oldham identified the separate arrival of P-waves, S-waves and surface waves on seismograms, in 1910, after studying the 1906 San Francisco earthquake, Harry Fielding Reid put forward the elastic rebound theory which remains the foundation for modern tectonic studies. The development of this depended on the considerable progress of earlier independent streams of work on the behaviour of elastic materials. In 1926, Harold Jeffreys was the first to claim, based on his study of waves, that below the mantle. In 1937, Inge Lehmann determined that within the liquid outer core there is a solid inner core. By the 1960s, earth science had developed to the point where a comprehensive theory of the causation of seismic events had come together in the now well-established theory of plate tectonics, seismic waves are elastic waves that propagate in solid or fluid materials. There are two types of waves, Pressure waves or Primary waves and Shear or Secondary waves. S-waves are transverse waves that move perpendicular to the direction of propagation, therefore, they appear later than P-waves on a seismogram. Fluids cannot support perpendicular motion, so S-waves only travel in solids, the two main surface wave types are Rayleigh waves, which have some compressional motion, and Love waves, which do not. Rayleigh waves result from the interaction of vertically polarized P- and S-waves that satisfy the conditions on the surface
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Isfjorden (Svalbard)
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Isfjorden is the second longest fjord in the Norwegian archipelago of Svalbard. It lies on the west side of Spitsbergen, an island in the Arctic Ocean about midway between Norway and the North Pole, and the largest in the archipelago. The mountain of Alkhornet stands on the side of the entrance to the fjord. A portion of Isfjorden is included in the parks of Norway as Nordre Isfjorden Land National Park. Around the fjord lie many of the largest settlements in Svalbard, Barentsburg, a Basque whaling ship from San Sebastian, under the command of Juan de Erauso and piloted by the Englishman Nicholas Woodcock, was the first to establish a temporary whaling station here in 1612. In 1613 French, Basque, and Dutch whaling ships resorted to Safehaven on the side of Isford or in Green Harbour on the south side of the fjord. All were either driven off by armed English ships or were forced to pay a fine of some sort, in 1614 the Dutch agreed to give Isfjorden to the English. The English continued to use Isfjorden as a base until at least the late 1650s. The Svenskehuset Tragedy occurred in 1872–73 at Cape Thordsen in Isfjorden, seventeen men died in Svenskehuset, now the oldest house on Spitsbergen. Today it is preserved as a heritage site. No Mans Land, A History of Spitsbergen from Its Discovery in 1596 to the Beginning of the Scientific Exploration of the Country, foraminifera from Isfjorden - illustrated catalogue
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Svalbard
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Svalbard is a Norwegian archipelago in the Arctic Ocean. Situated north of mainland Europe, it is midway between continental Norway and the North Pole. The islands of the range from 74° to 81° north latitude. The largest island is Spitsbergen, followed by Nordaustlandet and Edgeøya, administratively, the archipelago is not part of any Norwegian county, but forms an unincorporated area administered by a governor appointed by the Norwegian government. Since 2002, Svalbards main settlement, Longyearbyen, has had a local government. Other settlements include the Russian mining community of Barentsburg, the station of Ny-Ålesund. Svalbard is the northernmost settlement in the world with a permanent civilian population, other settlements are farther north, but are populated only by rotating groups of researchers. The islands were first taken into use as a base in the 17th and 18th centuries. Coal mining started at the beginning of the 20th century, the Svalbard Treaty of 1920 recognizes Norwegian sovereignty, and the 1925 Svalbard Act made Svalbard a full part of the Kingdom of Norway. They also established Svalbard as an economic zone and a demilitarized zone. The Norwegian Store Norske and the Russian Arktikugol remain the mining companies in place. Research and tourism have become important supplementary industries, with the University Centre in Svalbard, no roads connect the settlements, instead snowmobiles, aircraft and boats serve inter-community transport. Svalbard Airport, Longyear serves as the main gateway, the archipelago features an Arctic climate, although with significantly higher temperatures than other areas at the same latitude. The flora take advantage of the period of midnight sun to compensate for the polar night. Svalbard is a ground for many seabirds, and also features polar bears, reindeer, the Arctic fox. Seven national parks and twenty-three nature reserves cover two-thirds of the archipelago, protecting the largely untouched, yet fragile, approximately 60% of the archipelago is covered with glaciers, and the islands feature many mountains and fjords. Svalbard and Jan Mayen are collectively assigned the ISO 3166-1 alpha-2 country code SJ, both areas are administered by Norway, though they are separated by a distance of over 500 nautical miles and have very different administrative structures. The Svalbard Treaty of 1920 defines Svalbard as all islands, islets and skerries from 74° to 81° north latitude, the land area is 61,022 km2, and dominated by the island of Spitsbergen, which constitutes more than half the archipelago, followed by Nordaustlandet and Edgeøya
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Norway
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The Antarctic Peter I Island and the sub-Antarctic Bouvet Island are dependent territories and thus not considered part of the Kingdom. Norway also lays claim to a section of Antarctica known as Queen Maud Land, until 1814, the kingdom included the Faroe Islands, Greenland, and Iceland. It also included Isle of Man until 1266, Shetland and Orkney until 1468, Norway has a total area of 385,252 square kilometres and a population of 5,258,317. The country shares a long border with Sweden. Norway is bordered by Finland and Russia to the north-east, Norway has an extensive coastline, facing the North Atlantic Ocean and the Barents Sea. King Harald V of the Dano-German House of Glücksburg is the current King of Norway, erna Solberg became Prime Minister in 2013, replacing Jens Stoltenberg. A constitutional monarchy, Norway divides state power between the Parliament, the Cabinet and the Supreme Court, as determined by the 1814 Constitution, the kingdom is established as a merger of several petty kingdoms. By the traditional count from the year 872, the kingdom has existed continuously for 1,144 years, Norway has both administrative and political subdivisions on two levels, counties and municipalities. The Sámi people have an amount of self-determination and influence over traditional territories through the Sámi Parliament. Norway maintains close ties with the European Union and the United States, the country maintains a combination of market economy and a Nordic welfare model with universal health care and a comprehensive social security system. Norway has extensive reserves of petroleum, natural gas, minerals, lumber, seafood, the petroleum industry accounts for around a quarter of the countrys gross domestic product. On a per-capita basis, Norway is the worlds largest producer of oil, the country has the fourth-highest per capita income in the world on the World Bank and IMF lists. On the CIAs GDP per capita list which includes territories and some regions, from 2001 to 2006, and then again from 2009 to 2017, Norway had the highest Human Development Index ranking in the world. It also has the highest inequality-adjusted ranking, Norway ranks first on the World Happiness Report, the OECD Better Life Index, the Index of Public Integrity and the Democracy Index. Norway has two names, Noreg in Nynorsk and Norge in Bokmål. The name Norway comes from the Old English word Norðrveg mentioned in 880, meaning way or way leading to the north. In contrasting with suðrvegar southern way for Germany, and austrvegr eastern way for the Baltic, the Anglo-Saxon of Britain also referred to the kingdom of Norway in 880 as Norðmanna land. This was the area of Harald Fairhair, the first king of Norway, and because of him
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Johannes Walther
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Johannes Walther was a German geologist who discovered important principles of stratigraphy, including Walthers Law. Walther came from a home and studied botany, zoology. In 1882 he successfully completed this course with a doctorate, then he studied geology and palaeontology in Leipzig and later Munich. The following year he worked at the Stazione Zoologica in Naples as a lecturer, among other things, he ran extensive sedimentological and biological studies. In 1885 he returned to Jena and habilitated there in 1886 with a thesis on crinoids, after travelling, he was appointed as a professor at Jena in 1890. Walther moved to the University of Halle in 1906, staying until 1929, whilst there, he was in 1924 elected president of the prestigious German Academy of Sciences Leopoldina, an office he held until 1931
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Marine transgression
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A marine transgression is a geologic event during which sea level rises relative to the land and the shoreline moves toward higher ground, resulting in flooding. Transgressions can be caused either by the sinking or the ocean basins filling with water. Transgressions and regressions may be caused by events such as orogenies. During the Cretaceous, seafloor spreading created a relatively shallow Atlantic basin at the expense of deeper Pacific basin and this reduced the worlds ocean basin capacity and caused a rise in sea level worldwide. As a result of sea level rise, the oceans transgressed completely across the central portion of North America. The opposite of transgression is regression, in which the sea level relative to the land. Sedimentary facies changes may indicate transgressions and regressions and are easily identified. Thus, a transgression reveals itself in the column when there is a change from nearshore facies to offshore ones. A regression will feature the opposite pattern, with offshore facies changing to nearshore ones, the strata represent regressions less clearly, as their upper layers are often marked by an erosional unconformity. These are both idealized scenarios, in practice identifying transgression or regressions can be more complicated, for instance, a regression may be indicated by a change from carbonates to shale only, or a transgression from sandstone to shale, and so on. Lateral changes in facies are also important, a well-marked transgression sequence in an area where a sea was deep may be only partial farther away. One should consider such factors when interpreting a specific sedimentary column, current sea level rise Dunkirk transgression Ingression coast Marine terrace Sequence stratigraphy Submerged forest
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Marine regression
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Marine regression is a geological process occurring when areas of submerged seafloor are exposed above the sea level. The opposite event, marine transgression, occurs when flooding from the sea covers previously exposed land, at the time of the Permian-Triassic extinction, the largest extinction event in the Earths history, global sea level fell 250 m. Regressions are, therefore, seen as correlates or symptoms of major extinctions, however, that cause could not have applied in all, or even many, other cases. At the height of the last ice age, at around 18,000 years before the present, a cold spell around 6 million years ago was linked to an advance in glaciation, a marine regression, and the start of the Messinian salinity crisis in the Mediterranean basin. Some major regressions of the past, however, seem unrelated to glaciation episodes — the regression that accompanied the mass extinction at the end of the Cretaceous Period being one example. Marine transgression Holocene Transgression 8.2 kiloyear event Marine terrace Marine Transgression and Marine Regression, World of Earth Science
32.
Metamorphic facies
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A metamorphic facies is a set of metamorphic mineral assemblages that were formed under similar pressures and temperatures. The assemblage is typical of what is formed in conditions corresponding to an area on the two dimensional graph of temperature vs. pressure, Rocks which contain certain minerals can therefore be linked to certain tectonic settings, times and places in the geological history of the area. The boundaries between facies are wide because they are gradational and approximate, the name facies was first used for specific sedimentary environments in sedimentary rocks by Swiss geologist Amanz Gressly in 1838. Analogous with these sedimentary facies a number of metamorphic facies were proposed in 1920 by Finnish petrologist Pentti Eskola, eskolas classification was refined by New-Zealand geologist Francis John Turner throughout his career. A classic work of Turners was the book he published in 1948 titled Mineralogical and Structural Evolution of Metamorphic Rocks, Turner continued to work in the field, refining the metamorphic facies classifications through the end of his career in the early 1970s. The different metamorphic facies are defined by the composition of a rock. When the temperature or pressure in a body change, the rock can cross into a different facies. Whether minerals really react depends on the reaction kinetics, the energy of the reaction. The minerals in a rock and their age relations can be studied by optical microscopy or Scanning Electron Microscopy of thin sections of the rock. Apart from the metamorphic facies of a rock, a terrane can be described by the abbreviations LT, MT, HT, LP, MP. Since the 1980s the term UHP is used for rocks that saw extreme pressures, which minerals grow in a rock is also dependent of the original composition of the protolith. Carbonate rocks have a different composition from say a basalt lava, therefore, a metapsammite and a metapelite will have different mineralogical compositions even though they were in the same metamorphic facies. Every metamorphic facies has some index minerals by which it can be recognized and that does not mean these minerals will necessarily be visible with the naked eye, or even exist in the rock, when the rock did not have the right chemical composition they will not grow. Very typical index minerals are the polymorphs of aluminosilicate, andalusite is stable at low pressure, kyanite is stable at high pressure but relatively low temperature and sillimanite is stable at high temperature. The zeolite facies is the metamorphic facies with the lowest metamorphic grade, at lower temperature and pressure processes in the rock are called diagenesis. The facies is named for zeolites, strongly hydrated tectosilicates and it is named for the minerals prehnite and pumpellyite. The facies is named for the typical texture of the rocks. It is named after amphiboles that form under such circumstances, the depth at which it occurs is not constant
33.
Metamorphism
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Metamorphism is the change of minerals or geologic texture in pre-existing rocks, without the protolith melting into liquid magma. The change occurs primarily due to heat, pressure, and the introduction of chemically active fluids, the chemical components and crystal structures of the minerals making up the rock may change even though the rock remains a solid. Changes at or just beneath Earths surface due to weathering and/or diagenesis are not classified as metamorphism, Metamorphism typically occurs between diagenesis, and melting. Three types of metamorphism exist, contact, dynamic, and regional, Metamorphism produced with increasing pressure and temperature conditions is known as prograde metamorphism. Conversely, decreasing temperatures and pressure characterize retrograde metamorphism, Metamorphic rocks can change without melting. When pressure is applied, somewhat flattened grains that orient in the same direction have a stable configuration. The upper boundary of metamorphic conditions is related to the onset of melting processes in the rock, the maximum temperature for metamorphism is typically 700 –900 °C, depending on the pressure and on the composition of the rock. Migmatites are rocks formed at this limit, which contain pods. Since the 1980s it has recognized that rocks are rarely dry enough. Conditions producing widespread regionally metamorphosed rocks occur during an orogenic event, the collision of two continental plates or island arcs with continental plates produce the extreme compressional forces required for the metamorphic changes typical of regional metamorphism. These orogenic mountains are eroded, exposing the intensely deformed rocks typical of their cores. The conditions within the slab as it plunges toward the mantle in a subduction zone also produce regional metamorphic effects. The techniques of structural geology are used to unravel the collisional history, regional metamorphism can be described and classified into metamorphic facies or metamorphic zones of temperature/pressure conditions throughout the orogenic terrane. Contact metamorphism occurs typically around intrusive igneous rocks as a result of the increase caused by the intrusion of magma into cooler country rock. The area surrounding the intrusion where the contact metamorphism effects are present is called the metamorphic aureole, contact metamorphic rocks are usually known as hornfels. Rocks formed by contact metamorphism may not present signs of deformation and are often fine-grained. Contact metamorphism is greater adjacent to the intrusion and dissipates with distance from the contact, the size of the aureole depends on the heat of the intrusion, its size, and the temperature difference with the wall rocks. Dikes generally have small aureoles with minimal metamorphism whereas large ultramafic intrusions can have significantly thick, the metamorphic grade of an aureole is measured by the peak metamorphic mineral which forms in the aureole
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Metamorphic rock
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Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means change in form. The original rock is subjected to heat and pressure, causing profound physical and/or chemical change, the protolith may be a sedimentary, an igneous, or even an existing type of metamorphic rock. Metamorphic rocks make up a part of the Earths crust. They are classified by texture and by chemical and mineral assemblage and they may be formed simply by being deep beneath the Earths surface, subjected to high temperatures and the great pressure of the rock layers above it. They can form from tectonic processes such as continental collisions, which cause horizontal pressure and they are also formed when rock is heated up by the intrusion of hot molten rock called magma from the Earths interior. The study of rocks provides information about the temperatures and pressures that occur at great depths within the Earths crust. Some examples of rocks are gneiss, slate, marble, schist. Metamorphic minerals are those that only at the high temperatures and pressures associated with the process of metamorphism. These minerals, known as index minerals, include sillimanite, kyanite, staurolite, andalusite, and some garnet. Other minerals, such as olivines, pyroxenes, amphiboles, micas, feldspars, and quartz, may be found in metamorphic rocks and these minerals formed during the crystallization of igneous rocks. They are stable at temperatures and pressures and may remain chemically unchanged during the metamorphic process. However, all minerals are only within certain limits. The change in the size of the rock during the process of metamorphism is called recrystallization. Both high temperatures and pressures contribute to recrystallization, high temperatures allow the atoms and ions in solid crystals to migrate, thus reorganizing the crystals, while high pressures cause solution of the crystals within the rock at their point of contact. The layering within metamorphic rocks is called foliation, and it occurs when a rock is being shortened along one axis during recrystallization. This causes the platy or elongated crystals of minerals, such as mica and chlorite and this results in a banded, or foliated rock, with the bands showing the colors of the minerals that formed them. Textures are separated into foliated and non-foliated categories, foliated rock is a product of differential stress that deforms the rock in one plane, sometimes creating a plane of cleavage. For example, slate is a metamorphic rock, originating from shale
35.
Sequence stratigraphy
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The essence of the method is mapping of strata based on identification of surfaces which are assumed to represent time lines, and therefore placing stratigraphy in chronostratigraphic framework. Sequence stratigraphy is an alternative to a lithostratigraphic approach, which emphasizes similarity of the lithology of rock units rather than time significance. Sequence stratigraphy deals with genetically related sedimentary strata bounded by unconformities, the sequence part of the name refers to cyclic sedimentary deposits. Stratigraphy is the knowledge about the processes by which sedimentary deposits form and how those deposits change through time. Sequence boundaries are deemed the most significant surfaces, sequence boundaries are defined as unconformities or their correlative conformities. Sequence boundaries are formed due to the sea level fall, for example, multi-story fluvial sandstone packages often infill incised valleys formed by the sea level drop associated with sequence boundaries. The incised valleys of sequence boundaries correlate laterally with interfluves, palaeosols formed on the margins of incised valleys, the valley infills are not genetically related to underlying depositional systems as previous interpretations thought. Sandstone bodies associated with incised valleys can be good hydrocarbon reservoirs, there have been problems in the correlation and distribution of these bodies. Sequence stratigraphic principles and identification of significant surfaces have resolved some issues, parasequence boundaries may not form a barrier to hydrocarbon accumulation but may inhibit vertical reservoir communication. Sequence stratigraphic principles have optimized production potential once reservoir scale architecture is identified, the concept of systems tract evolved to link the contemporaneous depositional systems. Systems tract forms subdivision in a sequence, different kind of systems tracts are assigned on the basis of stratal stacking pattern, position in a sequence and in the sea level curve and types of bounding surfaces. A lowstand systems tract forms when the rate of sedimentation outpaces the rate of sea level rise during the stage of the sea level curve. It is bounded by a subaerial unconformity or its correlative conformity at the base, a transgressive systems tract is bounded by maximum regressive surface at the base and maximum flooding surface at the top. This systems tracts forms when the rate of sedimentation is outpaced by the rate of sea level rise in the sea level curves, highstand occurs during the late stage of base level rise when the rate of sea level rise drops below the sedimentation rate. In this period of sea level highstand is formed and it is bounded by maximum flooding surface at the base and composite surface at the top. Regressive systems tract forms in the part of the basin during the base level fall. Subaerial unconformities form in the side of the basin at the same time. A parasequence is a relatively conformable, genetically related succession of beds and bedsets bounded by marine flooding surfaces, the flooding surfaces bounding parasequences are not of the same scale as the regional transgressive surface that is associated with a sequence boundary
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Stratum
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In geology and related fields, a stratum is a layer of sedimentary rock or soil with internally consistent characteristics that distinguish it from other layers. The stratum is the unit in a stratigraphic column and forms the basis of the study of stratigraphy. Each layer is one of a number of parallel layers that lie one upon another. They may extend over hundreds of thousands of kilometers of the Earths surface. Strata are typically seen as bands of different colored or differently structured material exposed in cliffs, road cuts, quarries, individual bands may vary in thickness from a few millimeters to a kilometer or more. Each band represents a mode of deposition, river silt, beach sand, coal swamp, sand dune, lava bed. Geologists study rock strata and categorize them by the material of beds, each distinct layer is typically assigned to the name of sheet, usually based on a town, river, mountain, or region where the formation is exposed and available for study. For example, the Burgess Shale is an exposure of dark, occasionally fossiliferous. Slight distinctions in material in a formation may be described as members, formations are collected into groups while groups may be collected into supergroups. Archaeological horizon Geologic formation Geologic map Geologic unit Law of superposition Bed GeoWhen Database
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International Standard Book Number
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The International Standard Book Number is a unique numeric commercial book identifier. An ISBN is assigned to each edition and variation of a book, for example, an e-book, a paperback and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, the method of assigning an ISBN is nation-based and varies from country to country, often depending on how large the publishing industry is within a country. The initial ISBN configuration of recognition was generated in 1967 based upon the 9-digit Standard Book Numbering created in 1966, the 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108. Occasionally, a book may appear without a printed ISBN if it is printed privately or the author does not follow the usual ISBN procedure, however, this can be rectified later. Another identifier, the International Standard Serial Number, identifies periodical publications such as magazines, the ISBN configuration of recognition was generated in 1967 in the United Kingdom by David Whitaker and in 1968 in the US by Emery Koltay. The 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108, the United Kingdom continued to use the 9-digit SBN code until 1974. The ISO on-line facility only refers back to 1978, an SBN may be converted to an ISBN by prefixing the digit 0. For example, the edition of Mr. J. G. Reeder Returns, published by Hodder in 1965, has SBN340013818 -340 indicating the publisher,01381 their serial number. This can be converted to ISBN 0-340-01381-8, the check digit does not need to be re-calculated, since 1 January 2007, ISBNs have contained 13 digits, a format that is compatible with Bookland European Article Number EAN-13s. An ISBN is assigned to each edition and variation of a book, for example, an ebook, a paperback, and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, a 13-digit ISBN can be separated into its parts, and when this is done it is customary to separate the parts with hyphens or spaces. Separating the parts of a 10-digit ISBN is also done with either hyphens or spaces, figuring out how to correctly separate a given ISBN number is complicated, because most of the parts do not use a fixed number of digits. ISBN issuance is country-specific, in that ISBNs are issued by the ISBN registration agency that is responsible for country or territory regardless of the publication language. Some ISBN registration agencies are based in national libraries or within ministries of culture, in other cases, the ISBN registration service is provided by organisations such as bibliographic data providers that are not government funded. In Canada, ISBNs are issued at no cost with the purpose of encouraging Canadian culture. In the United Kingdom, United States, and some countries, where the service is provided by non-government-funded organisations. Australia, ISBNs are issued by the library services agency Thorpe-Bowker
38.
Principle of original horizontality
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The Principle of Original Horizontality states that layers of sediment are originally deposited horizontally under the action of gravity. It is a dating technique. The principle is important to the analysis of folded and tilted strata and it was first proposed by the Danish geological pioneer Nicholas Steno. As one of Stenos Laws, the Principle of Original Horizontality served well in the nascent days of geological science, however, it is now known that not all sedimentary layers are deposited purely horizontally. This is known as the angle of repose, and an example is the surface of sand dunes. Similarly, sediments may drape over an inclined surface, these sediments are usually deposited conformably to the pre-existing surface. Also sedimentary beds may pinch out along strike, implying that slight angles existed during their deposition, thus the Principle of Original Horizontality is widely, but not universally, applicable in the study of sedimentology, stratigraphy and structural geology. Law of superposition Principle of lateral continuity Principle of cross-cutting relationships Principle of faunal succession
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Law of superposition
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The law of superposition is an axiom that forms one of the bases of the sciences of geology, archaeology, and other fields dealing with geological stratigraphy. In its plainest form, it states that in undeformed stratigraphic sequences and this is important to stratigraphic dating, which assumes that the law of superposition holds true and that an object cannot be older than the materials of which it is composed. The law was first proposed in the 17th century by the Danish scientist Nicolas Steno, man made intrusions and activity in the archaeological record need not form chronologically from top to bottom or be deformed from the horizontal as natural strata are by equivalent processes. Some archaeological strata are created by undercutting previous strata, an example would be that the silt back-fill of an underground drain would form some time after the ground immediately above it. Other examples of non vertical superposition would be modifications to standing structures such as the creation of new doors, Superposition in archaeology requires a degree of interpretation to correctly identify chronological sequences and in this sense superposition in archaeology is more dynamic and multi-dimensional. K. The Earths Dynamic Systems, A Textbook in Physical Geology, by W. Kenneth Hamblin, BYU, Provo, UT, william L. Chesser, Dennis Tasa, c 1978, pg. 115, The Principle of Superposition and Original Horizontality, pg,116, The Principle of Faunal Succession, The Principle of Crosscutting Relations, pg 116-17, The Principle of Inclusion. 40 figs.1 pl.136 pp. London & New York, Academic Press ISBN 0-12-326650-5
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Principle of lateral continuity
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The principle of lateral continuity states that layers of sediment initially extend laterally in all directions, in other words, they are laterally continuous. As a result, rocks that are similar, but are now separated by a valley or other erosional feature. Layers of sediment do not extend indefinitely, rather, the limits can be recognized and are controlled by the amount and type of sediment available, as long as sediment is transported to an area, it will eventually be deposited. However, as the amount of material away from the source. Often, coarser-grained material can no longer be transported to an area because the medium has insufficient energy to carry it to that location. In its place, the particles that settle from the medium will be finer-grained. The lateral variation in sediment within a stratum is known as sedimentary facies, if sufficient sedimentary material is available, it will be deposited up to the limits of the sedimentary basin. Often, the basin is within rocks that are very different from the sediments that are being deposited. In those cases, the limits of the sedimentary layer will be marked by an abrupt change in rock type
41.
Cross-cutting relationships
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Cross-cutting relationships is a principle of geology that states that the geologic feature which cuts another is the younger of the two features. It is a dating technique in geology. There are several types of cross cutting relationships, Structural relationships may be faults or fractures cutting through an older rock. Intrusional relationships occur when an igneous pluton or dike is intruded into pre-existing rocks, stratigraphic relationships may be an erosional surface cuts across older rock layers, geological structures, or other geological features. Sedimentological relationships occur where currents have eroded or scoured older sediment in an area to produce, for example. Paleontological relationships occur where animal activity or plant growth produces truncation and this happens, for example, where animal burrows penetrate into pre-existing sedimentary deposits. Geomorphological relationships may occur where a feature, such as a river. In a similar example, an impact crater excavates into a layer of rock. Cross-cutting relationships may be compound in nature, for example, if a fault were truncated by an unconformity, and that unconformity cut by a dike. Based upon such compound cross-cutting relationships it can be seen that the fault is older than the unconformity which in turn is older than the dike, using such rationale, the sequence of geological events can be better understood. Cross-cutting relationships may be seen cartographically, megascopically, and microscopically, in other words, these relationships have various scales. A cartographic crosscutting relationship might look like, for example, a large fault dissecting the landscape on a large map, megascopic cross-cutting relationships are features like igneous dikes, as mentioned above, which would be seen on an outcrop or in a limited geographic area. Microscopic cross-cutting relationships are those that require study by magnification or other close scrutiny, for example, penetration of a fossil shell by the drilling action of a boring organism is an example of such a relationship. Cross-cutting relationships can also be used in conjunction with radiometric age dating to effect an age bracket for geological materials that cannot be dated by radiometric techniques. A radiometric age date from crystals in dike A will give the age date for the layer in question and likewise. This provides an age bracket, or range of possible ages, Principle of original horizontality Principle of lateral continuity Principle of faunal succession Cross Cutting. Ed. K. Lee Lerner and Brenda Wilmoth Lerner, nicolai Stenonis solido intra solidum naturaliter contento dissertationis prodromus. Florentiae, ex typographia sub signo Stellae Hutton, James, theory of the Earth,1795 Lyell, Charles
42.
Facies
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Ideally, a sedimentary facies is a distinctive rock unit that forms under certain conditions of sedimentation, reflecting a particular process or environment. Sedimentary facies are either descriptive or interpretative, sedimentary facies are bodies of sediment that are recognizably distinct from adjacent sediments that resulted from different depositional environments. Generally, geologists distinguish facies by the aspect of the rock or sediment being studied, Facies based on petrological characters are called lithofacies, whereas facies based on fossil content are called biofacies. A facies is usually further subdivided, for example, one might refer to a tan, the characteristics of the rock unit come from the depositional environment and from the original composition. Sedimentary facies reflect their depositional environment, each facies being a kind of sediment for that area or environment. Since its inception, the concept has been extended to related geological concepts. For example, characteristic associations of organic microfossils, and particulate organic material, discrete seismic units are similarly referred to as seismic facies. Walthers Law of Facies, or simply Walthers Law, named after the geologist Johannes Walther, conversely, it states that when a depositional environment migrates laterally, sediments of one depositional environment come to lie on top of another. In Russia the law is known as Golovkinsky-Walthers Law, honoring also Nikolai A. Golovkinsky, a classic example of this law is the vertical stratigraphic succession that typifies marine transgressions and regressions. The sequence of minerals that develop during progressive metamorphism define a facies series, seismic facies are mappable three-dimensional seismic units composed of reflection units whose parameters differ from adjacent facies units. Lithofacies Metamorphic rock Sequence stratigraphy Stratum
