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Oolite
Oolite or oölite () is a sedimentary rock formed from ooids, spherical grains composed of concentric layers. Strictly, oolites consist of ooids of diameter 0.25–2 millimetres; rocks composed of ooids larger than 2 mm are called pisolites. The term ''oolith'' can refer to oolite or individual ooids. Composition Ooids are most commonly composed of calcium carbonate (calcite or aragonite), but can be composed of phosphate, clays, chert, dolomite or iron minerals, including hematite. Dolomitic and chert ooids are most likely the result of the replacement of the original texture in limestone. Oolitic hematite occurs at Red Mountain near Birmingham, Alabama, along with oolitic limestone. They are usually formed in warm, supersaturated, shallow, highly agitated marine water intertidal environments, though some are formed in inland lakes. The mechanism of formation starts with a small fragment of sediment acting as a 'seed', such as a piece of a shell. Strong intertidal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hunts Bay Oolite
Hunts Bay Oolite is an oolite, oolitic Carboniferous limestone Formation (geology), geological formation found in the south Wales region. It is named after Hunts Bay on the Gower peninsula, south-south west of Bishopston, Swansea, Bishopston, where a significant amount of the limestone forms the cliffs there. Hunts Bay Oolite is a sub-group of the Pembroke Limestone Group which itself is part of the Carboniferous Limestone Supergroup. Oolite means 'egg stone': very small grains (up to 2mm) form by accumulating precipitated minerals, usually calcium carbonate. These ooids, created in a warm, tropical environment, are the precursors to the limestone. The Hunts Bay Oolite extends from Pembroke, Pembrokeshire, Pembroke in the West to Monmouth and Chepstow in the East and northwards into the Dowlais Limestone Formation around Merthyr Tydfil. Fossils, such as brachiopods and crinoids associated with a shallow sea environment, can be found in the rock. East of the South Wales Coalfield ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cotswold Hills
The Cotswolds ( ) is a region of central South West England, along a range of rolling hills that rise from the meadows of the upper River Thames to an escarpment above the Severn Valley and the Vale of Evesham. The area is defined by the bedrock of Jurassic limestone that creates a type of grassland habitat that is quarried for the golden-coloured Cotswold stone. It lies across the boundaries of several English counties: mainly Gloucestershire and Oxfordshire, and parts of Wiltshire, Somerset, Worcestershire, and Warwickshire. The highest point is Cleeve Hill at , just east of Cheltenham. The predominantly rural landscape contains stone-built villages, towns, stately homes and gardens featuring the local stone. A large area within the Cotswolds has been designated as a National Landscape (formerly known as Area of Outstanding Natural Beauty, or AONB) since 1966. The designation covers , with boundaries roughly across and long, stretching south-west from just south of St ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bath Stone
Bath Stone is an oolitic limestone comprising granular fragments of calcium carbonate originally obtained from the Middle Jurassic aged Great Oolite Group of the Combe Down and Bathampton Down Mines under Combe Down, Somerset, England. Its honey colouring gives the World Heritage City of Bath, England, its distinctive appearance. An important feature of Bath Stone is that it is a ' freestone', so-called because it can be sawn or 'squared up' in any direction, unlike other rocks such as slate, which form distinct layers. Bath Stone has been used extensively as a building material throughout southern England, for churches, houses, and public buildings such as railway stations. Some quarries are still in use, but the majority have been converted to other purposes or are being filled in. Geological formation Bath Stone is an oolitic limestone comprising granular fragments of calcium carbonate laid down during the Jurassic Period (195 to 135 million years ago) when the regio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ooid
Ooids (, ) are small (commonly ≤2 mm in diameter), spheroidal, "coated" (layered) sedimentary grains, usually composed of calcium carbonate, but sometimes made up of iron- or phosphate-based minerals. Ooids usually form on the sea floor, most commonly in shallow tropical seas (around the Bahamas, for example, or in the Persian Gulf). After being buried under additional sediment, these ooid grains can be cemented together to form a sedimentary rock called an '' oolite''. Oolites usually consist of calcium carbonate; these belong to the limestone rock family. Pisoids are similar to ooids, but are larger than 2 mm in diameter, often considerably larger, as with the pisoids in the hot springs at Carlsbad (Karlovy Vary) in the Czech Republic. Ooids have been the subject of scientific research for centuries.https://www.geological-digressions.com/the-mineralogy-of-carbonates-non-skeletal-grains/ Formation An ooid forms as a series of concentric layers around a nucleus. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limestone
Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science), crystal forms of calcium carbonate . Limestone forms when these minerals Precipitation (chemistry), 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 (rock), dolomite, a closely related rock, which contains a high percentage of the mineral Dolomite (mine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jurassic
The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. The Jurassic constitutes the second and middle period of the Mesozoic, Mesozoic Era as well as the eighth period of the Phanerozoic, Phanerozoic Eon and is named after the Jura Mountains, where limestone strata from the period were first identified. The start of the Jurassic was marked by the major Triassic–Jurassic extinction event, associated with the eruption of the Central Atlantic magmatic province, Central Atlantic Magmatic Province (CAMP). The beginning of the Toarcian Age started around 183 million years ago and is marked by the Toarcian Oceanic Anoxic Event, a global episode of Anoxic event, oceanic anoxia, ocean acidification, and elevated global temperatures associated with extinctions, likely caused by the eruption of the Kar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isle Of Portland
The Isle of Portland is a tied island, long by wide, in the English Channel. The southern tip, Portland Bill, lies south of the resort of Weymouth, Dorset, Weymouth, forming the southernmost point of the county of Dorset, England. A barrier beach called Chesil Beach joins Portland with mainland England. The A354 road passes down the Portland end of the beach and then over the Fleet Lagoon by bridge to the mainland. The population of Portland is 13,417. Portland is a central part of the Jurassic Coast, a World Heritage Site on the Dorset and east Devon coast, important for its geology and landforms. Portland stone, a limestone famous for its use in British and world architecture, including St Paul's Cathedral and the United Nations Headquarters, continues to be quarried here. Portland Harbour, in between Portland and Weymouth, is one of the largest man-made harbours in the world. The harbour was made by the building of stone breakwater (structure), breakwaters between 1848 a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pisolite
A pisolite () is a sedimentary rock made of pisoids, which are concretionary grains – typically of calcium carbonate which resemble ooids, but are more than 2 mm in diameter. These grains are approximately spherical and have concentric layers reaching 10 mm in diameter. Bauxites, limonites, and siderites often have a pisolitic structure. See also * Ooid * Oolite Oolite or oölite () is a sedimentary rock formed from ooids, spherical grains composed of concentric layers. Strictly, oolites consist of ooids of diameter 0.25–2 millimetres; rocks composed of ooids larger than 2 mm are called pis ... References Further reading * Sedimentary rocks {{sedimentary-rock-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sedimentary Rock
Sedimentary rocks are types of rock (geology), rock formed by the cementation (geology), cementation of sediments—i.e. particles made of minerals (geological detritus) or organic matter (biological detritus)—that have been accumulated or deposited at Earth's surface. Sedimentation is any process that causes these particles to settle in place. Geological detritus originates from weathering and erosion of existing rocks, or from the solidification of molten lava blobs erupted by volcanoes. The geological detritus is transported to the place of deposition by water, wind, ice or Mass wasting, mass movement, which are called agents of denudation. Biological detritus is formed by bodies and parts (mainly shells) of dead aquatic organisms, as well as their fecal mass, suspended in water and slowly piling up on the floor of water bodies (marine snow). Sedimentation may also occur when dissolved minerals precipitate from aqueous solution, water solution. The sedimentary rock cover of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Current Bedding
In geology, cross-bedding, also known as cross-stratification, is layering within a stratum and at an angle to the main bedding plane. The sedimentary structures which result are roughly horizontal units composed of inclined layers. The original depositional layering is tilted, such tilting not being the result of post-depositional deformation. Cross-beds or "sets" are the groups of inclined layers, which are known as cross-strata. Cross-bedding forms during deposition on the inclined surfaces of bedforms such as ripples and dunes; it indicates that the depositional environment contained a flowing medium (typically water or wind). Examples of these bedforms are ripples, dunes, antidunes, sand waves, hummocks, bars, and delta slopes.Collinson, J.D., Thompson, D.B., 1989, Sedimentary Structures (2nd ed): Academic Division of Unwin Hyman Ltd, Winchester, MA, XXX p. Environments in which water movement is fast enough and deep enough to develop large-scale bed forms fall into thr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North York Moors
The North York Moors is an upland area in north-eastern Yorkshire, England. It contains one of the largest expanses of Calluna, heather moorland in the United Kingdom. The area was designated as a national parks of England and Wales, National Park in 1952, through the National Parks and Access to the Countryside Act 1949. Covering an area of , the National Park has a population of 23,380. It is administered by the North York Moors National Park Authority, which is based in Helmsley. Location and transport To the east, the area is clearly defined by the impressive cliffs of the North Sea coast. The northern and western boundaries are defined by the steep scarp slopes of the Cleveland Hills edging the Tees lowlands and the Hambleton Hills above the Vale of Mowbray. To the south lies the broken line of the Tabular Hills and the Vale of Pickering. Four roads cross the North York Moors from north to south. In the east, the A171 road, A171 joins Whitby and Scarborough, North Yorkshi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Portland Stone
Portland stone is a limestone geological formation (formally named the Portland Stone Formation) dating to the Tithonian age of the Late Jurassic that is quarried on the Isle of Portland in Dorset, England. The quarries are cut in beds of white-grey limestone separated by chert beds. It has been used extensively as a building stone throughout the British Isles, notably in major public buildings in London such as St Paul's Cathedral and Buckingham Palace. Portland stone is also exported to many countries, being used for example at the United Nations headquarters in New York City. Geology Portland stone formed in a marine environment, on the floor of a shallow, warm, sub-tropical sea probably near land (as evidenced by fossilised driftwood, which is not uncommon). When seawater is warmed by the sun, its capacity to hold dissolved gas is reduced; consequently, dissolved carbon dioxide (CO2) is released into the atmosphere as a gas. Calcium and bicarbonate ions within the wat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
