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Lower Greensand Group
The Lower Greensand Group is a geological unit present across large areas of Southern England. It was deposited during the Aptian and Albian stages of the Early Cretaceous. It predominantly consists of sandstone and unconsolidated sand that were deposited in shallow marine conditions. Lithology The Lower Greensand typically comprises loose, unconsolidated sandstone (termed rubblestone/rubble in construction) and sands of varying grain size with subordinate amounts of siltstones, mudstones (containing smectites and similar) and limestones. The name "greensand" is derived from the presence of the green coloured mineral glauconite, which forms in shallow marine conditions. In the Weald of East Sussex the lowermost part of the group is recognised by green glauconitic clays with a basal bed of phosphate nodules. These clays are overlain by green sandy clays and silts and finally homogeneous fine grained sands.Lake, R.D. & Shepard-Thorn, E.R. (1987) ''Geology of the country around ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dryhill
Dryhill is a small hamlet in the Sevenoaks district, in the county of Kent, England. Location It is about two miles away from the large town of Sevenoaks, located near the A25 road between Sevenoaks and Sundridge. Transport For transport there is the Sevenoaks railway station and the A25 road, the M25 motorway The M25 or London Orbital Motorway is a major road encircling most of Greater London. The motorway is one of the most important roads in the UK and one of the busiest. Margaret Thatcher opened the final section in 1986, making the M25 the lon ..., M20 motorway and the M26 motorway nearby. Local Nature Reserve The Dryhill Local Nature Reserve based on an old ragstone quarry at the edge of the village covers some 20 hectares ( ). The quarry is also a Geological interest listed Site of Special Scientific Interest. It is no longer managed by Kent County Council, but remains open as a Country Park and picnic area. References * A-Z Great Britain Ro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gallois Geological Map Of Wealden District 1965
Gallois as a French word means "Welsh". ''Le gallois'' (in lower case) refers to the Welsh language; ''un Gallois'' (capitalised) means "a Welshman" and ''une Galloise'' (capitalised) means "a Welshwoman. It may refer to: People * Gallois (surname) * Évariste Galois (1811–1832), French mathematician Other * '' Perceval le Gallois'' (1978) French film directed by Éric Rohmer * Galois theory, a mathematical theory connecting field theory and group theory See also * ''Gaulois'', French for a person of Gaul Gaul ( la, Gallia) was a region of Western Europe first described by the Romans. It was inhabited by Celtic and Aquitani tribes, encompassing present-day France, Belgium, Luxembourg, most of Switzerland, parts of Northern Italy (only durin ... * Gauloises, a brand of French cigarettes {{disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High (tectonics)
A high in structural geology and tectonics an area where tectonic uplift has taken place relative to its surroundings. Highs are often bounded by normal faults and can be regarded as the opposites of basins. A related word is a massif, an area where relative old rocks layers are found at the surface. A small high can be called a horst. Because of the relative uplift the accommodation space for sediments was relatively small and a high will have thinner sedimentary layers deposited on it compared to the surrounding basins. Therefore, highs are not good places to study stratigraphic sequences as the sequence may be less detailed or even absent. See also *Anteclise In geology, a massif ( or ) is a section of a planet's crust that is demarcated by faults or flexures. In the movement of the crust, a massif tends to retain its internal structure while being displaced as a whole. The term also refers to a ... References Tectonics {{tectonics-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marine Transgression
A marine transgression is a geologic event during which sea level rises relative to the land and the shoreline moves toward higher ground, which results in flooding. Transgressions can be caused by the land sinking or by the ocean basins filling with water or decreasing in capacity. Transgressions and regressions may be caused by tectonic events such as orogenies, severe climate change such as ice ages or isostatic adjustments following removal of ice or sediment load. During the Cretaceous, seafloor spreading created a relatively shallow Atlantic basin at the expense of deeper Pacific basin. That reduced the world's ocean basin capacity and caused a rise in sea level worldwide. As a result of the sea level rise, the oceans transgressed completely across the central portion of North America and created the Western Interior Seaway from the Gulf of Mexico to the Arctic Ocean. The opposite of transgression is regression in which the sea level falls relative to the land and e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Upper Greensand Formation
The Upper Greensand Formation is a Cretaceous formation of Albian to Cenomanian in age, found within the Wessex Basin and parts of the Weald Basin in southern England. It overlies the Gault Clay and underlies the Chalk Group. It varies in thickness from zero to 75 m. It is predominantly a glauconitic fine-grained sandstone, locally becoming silty. Fragmentary dinosaur remains, such as those assigned to '' Iuticosaurus'', have been recovered from this formation. It has been quarried as a building stone from Roman times, and used in London and the area of its outcrop from Devon to East Sussex. Use Sandstones from the Upper Greensand have been used as building stone since at least Roman times. Reigate Stone was mined from the Upper Greensand in north east Surrey throughout the middle ages and early modern period, forming the most important source of freestone in Medieval London. In Dorset, the Shaftesbury Sandstone was quarried between Shaftesbury and Okeford Fitzpaine a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stage (stratigraphy)
In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries. Rock series are divided into stages, just as geological epochs are divided into ages. Stages can be divided into smaller stratigraphic units called chronozones. (See chart at right for full terminology hierarchy.) Stages may also be divided into substages or indeed grouped as superstages. The term faunal stage is sometimes used, referring to the fact that the same fauna (animals) are found throughout the layer (by definition). Definition Stages are primarily defined by a consistent set of fossils (biostratigraphy) or a consistent magnetic polarity (see paleomagnetism) in the rock. Usually one or more index fossils that are common, found worldwide, easily recognized, and limited to a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Early Cretaceous
The Early Cretaceous (geochronological name) or the Lower Cretaceous ( chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Proposals for the exact age of the Barremian-Aptian boundary ranged from 126 to 117 Ma until recently (as of 2019), but based on drillholes in Svalbard the defining early Aptian Oceanic Anoxic Event 1a (OAE1a) was carbon isotope dated to 123.1±0.3 Ma, limiting the possible range for the boundary to c. 122–121 Ma. There is a possible link between this anoxic event and a series of Early Cretaceous large igneous provinces (LIP). The Ontong Java- Manihiki- Hikurangi large igneous province, emplaced in the South Pacific at c. 120 Ma, is by far the largest LIP in Earth's history. The Ontong Java Plateau today covers an area of 1,860,000 km2. In the Indian Ocean another LIP began to form at c. 120 Ma, the Kergue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphate Nodule
Phosphorite, phosphate rock or rock phosphate is a non-detrital sedimentary rock that contains high amounts of phosphate minerals. The phosphate content of phosphorite (or grade of phosphate rock) varies greatly, from 4% to 20% phosphorus pentoxide (P2O5). Marketed phosphate rock is enriched ("beneficiated") to at least 28%, often more than 30% P2O5. This occurs through washing, screening, de-liming, magnetic separation or flotation. By comparison, the average phosphorus content of sedimentary rocks is less than 0.2%.Blatt, Harvey and Robert J. Tracy, ''Petrology'', Freeman, 1996, 2nd ed. pp. 345–349 The phosphate is present as fluorapatite Ca5(PO4)3F typically in cryptocrystalline masses (grain sizes < 1 μm) referred to as -sedimentary apatite deposits of uncertain origin. It is also present as |
East Sussex
East Sussex is a ceremonial and non-metropolitan county in South East England on the English Channel coast. It is bordered by Kent to the north and east, West Sussex to the west, and Surrey to the north-west. The largest settlement in East Sussex is the city of Brighton and Hove. History East Sussex is part of the historic county of Sussex, which has its roots in the ancient kingdom of the South Saxons, who established themselves there in the 5th century AD, after the departure of the Romans. Archaeological remains are plentiful, especially in the upland areas. The area's position on the coast has also meant that there were many invaders, including the Romans and later the Normans. Earlier industries have included fishing, iron-making, and the wool trade, all of which have declined, or been lost completely. Governance Sussex was historically sub-divided into six rapes. From the 12th century the three eastern rapes together and the three western rapes together had ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weald
The Weald () is an area of South East England between the parallel chalk escarpments of the North and the South Downs. It crosses the counties of Hampshire, Surrey, Sussex and Kent. It has three separate parts: the sandstone "High Weald" in the centre; the clay "Low Weald" periphery; and the Greensand Ridge, which stretches around the north and west of the Weald and includes its highest points. The Weald once was covered with forest, and its name, Old English in origin, signifies "woodland". The term is still used today, as scattered farms and villages sometimes refer to the Weald in their names. Etymology The name "Weald" is derived from the Old English ', meaning "forest" (cognate of German ''Wald'', but unrelated to English "wood", which has a different origin). This comes from a Germanic root of the same meaning, and ultimately from Indo-European. ''Weald'' is specifically a West Saxon form; ''wold'' is the Anglian form of the word. The Middle English form of the w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glauconite
Glauconite is an iron potassium phyllosilicate (mica group) mineral of characteristic green color which is very friable and has very low weathering resistance. It crystallizes with a monoclinic geometry. Its name is derived from the Greek () meaning 'bluish green', referring to the common blue-green color of the mineral; its sheen (mica glimmer) and blue-green color. Its color ranges from olive green, black green to bluish green, and yellowish on exposed surfaces due to oxidation. In the Mohs scale it has hardness of 2. The relative specific gravity range is 2.4 - 2.95. It is normally found in dark green rounded brittle pellets, and with the dimension of a sand grain size. It can be confused with chlorite (also of green color) or with a clay mineral. Glauconite has the chemical formula . Glauconite particles are one of the main components of greensand, glauconitic siltstone and glauconitic sandstone. Glauconite has been called a marl in an old and broad sense of that wo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms when these minerals precipitate out of water containing dissolved calcium. This can take place through both biological and nonbiological processes, though biological processes, such as the accumulation of corals and shells in the sea, have likely been more important for the last 540 million years. Limestone often contains fossils which provide scientists with information on ancient environments and on the evolution of life. About 20% to 25% of sedimentary rock is carbonate rock, and most of this is limestone. The remaining carbonate rock is mostly dolomite, a closely related rock, which contains a high percentage of the mineral dolomite, . ''Magnesian limestone'' is an obsolete and poorly-defined term used variously for dolomite, for lime ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
