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Blackrock (geology)
The Pembroke Limestone Group is a stratigraphic unit of Courceyan to Brigantian age (Early Carboniferous) found in southern Wales and northern Somerset. It forms part of the Carboniferous Limestone Supergroup. These carbonate rocks developed in platform and ramp environments and are up to 1025m thick in places. The make-up of the Group varies from one part of the basin to another but in south Pembrokeshire it comprises the following formations: *Oystermouth Formation *Oxwich Head Limestone Formation *Stackpole Limestone Formation *Pen-y-Holt Limestone Formation *Hobbyhorse Bay Limestone Formation *Linney Head Formation *Berry Slade Limestone Formation *Black Rock Limestone Subgroup In the Tenby, Gower and Vale of Glamorgan areas, the Stackpole Formation is replaced by the Hunt's Bay Oolite Subgroup which consists of a lower/earlier Cornelly Oolite Formation and an upper/later Stormy Limestone Formation. Likewise the Linney Head to Pen-y-Holt sequence is replaced by a triparti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oolite
Oolite or oölite (''egg stone'') is a sedimentary rock formed from ooids, spherical grains composed of concentric layers. The name derives from the Ancient Greek word for egg (ᾠόν). 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbonate Platform
A carbonate platform is a sedimentary body which possesses topographic relief, and is composed of autochthonic calcareous deposits. Platform growth is mediated by sessile organisms whose skeletons build up the reef or by organisms (usually microbes) which induce carbonate precipitation through their metabolism. Therefore, carbonate platforms can not grow up everywhere: they are not present in places where limiting factors to the life of reef-building organisms exist. Such limiting factors are, among others: light, water temperature, transparency and pH-Value. For example, carbonate sedimentation along the Atlantic South American coasts takes place everywhere but at the mouth of the Amazon River, because of the intense turbidity of the water there. Spectacular examples of present-day carbonate platforms are the Bahama Banks under which the platform is roughly 8 km thick, the Yucatan Peninsula which is up to 2 km thick, the Florida platform, the platform on which the Grea ... [...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 limes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Argillaceous
Clay minerals are hydrous aluminium phyllosilicates (e.g. kaolin, Al2 Si2 O5( OH)4), sometimes with variable amounts of iron, magnesium, alkali metals, alkaline earths, and other cations found on or near some planetary surfaces. Clay minerals form in the presence of water and have been important to life, and many theories of abiogenesis involve them. They are important constituents of soils, and have been useful to humans since ancient times in agriculture and manufacturing. Properties Clay is a very fine-grained geologic material that develops plasticity when wet, but becomes hard, brittle and non–plastic upon drying or firing. It is a very common material, and is the oldest known ceramic. Prehistoric humans discovered the useful properties of clay and used it for making pottery. The chemistry of clay, including its capacity to retain nutrient cations such as potassium and ammonium, is important to soil fertility. Because the individual particles in clay are less than ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Avon Gorge
The Avon Gorge () is a 1.5-mile (2.5-kilometre) long gorge on the River Avon in Bristol, England. The gorge runs south to north through a limestone ridge west of Bristol city centre, and about 3 miles (5 km) from the mouth of the river at Avonmouth. The gorge forms the boundary between the unitary authorities of North Somerset and Bristol, with the boundary running along the south bank. As Bristol was an important port, the gorge formed a defensive gateway to the city. On the east of the gorge is the Bristol suburb of Clifton, and The Downs, a large public park. To the west of the gorge is Leigh Woods, the name of both a village and the National Trust forest it is situated in. There are three Iron Age hill forts overlooking the gorge, as well as an observatory. The Clifton Suspension Bridge, an icon of Bristol, crosses the gorge. Geology and formation The gorge cuts through a ridge mainly of limestone, with some sandstone. This particular ridge runs from Cli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mendip Hills
The Mendip Hills (commonly called the Mendips) is a range of limestone hills to the south of Bristol and Bath in Somerset, England. Running from Weston-super-Mare and the Bristol Channel in the west to the Frome valley in the east, the hills overlook the Somerset Levels to the south and the Chew Valley and other tributaries of the Avon to the north. The hills give their name to the local government district of Mendip, which administers most of the area. The higher, western part of the hills, covering has been designated an Area of Outstanding Natural Beauty (AONB), which gives it a level of protection comparable to a national park. The hills are largely formed from Carboniferous Limestone, which is quarried at several sites. Ash–maple woodland, calcareous grassland and mesotrophic grassland which can be found across the Mendip Hills provide nationally important semi-natural habitats. With their temperate climate these support a range of flora and fauna including birds, but ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Severn Estuary
The Severn Estuary ( cy, Aber Hafren) is the estuary of the River Severn, flowing into the Bristol Channel between South West England and South Wales. Its high tidal range, approximately , means that it has been at the centre of discussions in the UK regarding renewable energy. Geography Definitions of the limits of the Severn Estuary vary. At the upstream boundary, the tidal limit of the river is at Gloucester. Downstream, the International Hydrographic Organization places the boundary between the estuary and the open sea of the Bristol Channel at a line between Sand Point, Somerset (immediately north of Weston-super-Mare) and Lavernock Point (immediately south of Penarth in south Wales). This definition is used by the Severn Estuary Partnership and Visit England. A narrower definition adopted for navigation purposes by some maps includes only the area downstream of the Second Severn Crossing near Severn Beach, South Gloucestershire. The definition used on Admiralty Chart SC ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stratigraphic Unit
A stratigraphic unit is a volume of rock of identifiable origin and relative age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features (facies) that characterize it. 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 terms such as "when the sandstone component exceeds 75%". Lithostratigraphic units Sequences of sedimentary and volcanic rocks are subdivided the basis of their shared or associated lithology. Formally identified lithostratigraphic units are structured in a hierarchy of lithostratigraphic rank, higher rank units generally comprising two or more units of lower rank. Going from smaller to larger in rank, the main lithostratigraphic ranks are Bed, Member, Formation, Group and Supergroup. Formal names of lithostratigraphic units are assigned by geological surveys. Units of formation or hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South Wales Coalfield
The South Wales Coalfield ( cy, Maes glo De Cymru) extends across Pembrokeshire, Carmarthenshire, Swansea, Neath Port Talbot, Bridgend, Rhondda Cynon Taf, Merthyr Tydfil, Caerphilly, Blaenau Gwent and Torfaen. It is rich in coal deposits, especially in the South Wales Valleys. Description It comprises a fully exposed synclinorium with a varying thickness of coal measures (Upper Carboniferous/Pennsylvanian) with thick, workable seams in the lower parts and generally thinner and sparser seams in the upper parts, together with a development of sandstones (Pennant Sandstone). These sandstones have been much used in building construction (including the characteristic terraces of former miners' houses) and give rise to bleak uplands rising 300–600 metres above sea level between the steep-sided valleys in which most deep mines were developed. The coal generally increases in grade or "rank" from east to west, with bituminous coals in the east, and anthracite in the west, mostly to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Newport, Wales
Newport ( cy, Casnewydd; ) is a city and Local government in Wales#Principal areas, county borough in Wales, situated on the River Usk close to its confluence with the Severn Estuary, northeast of Cardiff. With a population of 145,700 at the 2011 census, Newport is the third-largest authority with City status in the United Kingdom, city status in Wales, and seventh List of Welsh principal areas, most populous overall. Newport became a unitary authority in 1996 and forms part of the Cardiff-Newport metropolitan area. Newport was the site of the last large-scale armed insurrection in Great Britain, the Newport Rising of 1839. Newport has been a port since medieval times when the first Newport Castle was built by the Normans. The town outgrew the earlier Roman Britain, Roman town of Caerleon, immediately upstream and now part of the borough. Newport gained its first Municipal charter, charter in 1314. It grew significantly in the 19th century when its port became the focus of Coa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vale Of Glamorgan
The Vale of Glamorgan ( cy, Bro Morgannwg ), often referred to as The Vale, is a county borough in the south-east of Wales. It borders Bridgend County Borough to the west, Cardiff to the east, Rhondda Cynon Taf to the north, and the Bristol Channel to the south. With an economy based largely on agriculture and chemicals, it is the southernmost unitary authority in Wales. Attractions include Barry Island Pleasure Park, the Barry Tourist Railway, Medieval wall paintings in St Cadoc's Church, Llancarfan, Porthkerry Park, St Donat's Castle, Cosmeston Lakes Country Park and Cosmeston Medieval Village. The largest town is Barry. Other towns include Penarth, Llantwit Major, and Cowbridge. There are many villages in the county borough. History The area is the southernmost part of the county of Glamorgan. Between the 11th century and 1536 the area was part of the Lordship of Glamorgan. In medieval times, the village of Cosmeston, near what is today Penarth in the south east of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gower
Gower ( cy, Gŵyr) or the Gower Peninsula () in southwest Wales, projects towards the Bristol Channel. It is the most westerly part of the historic county of Glamorgan. In 1956, the majority of Gower became the first area in the United Kingdom to be designated an Area of Outstanding Natural Beauty. Until 1974, Gower was administered as a rural district. It was then merged with the county borough of Swansea. From 1974 to 1996, it formed the Swansea district. Since 1996, Gower has been administered as part of the unitary authority of the City and County of Swansea. Since its establishment in 1999, the Gower Senedd constituency has only elected Labour members. The Gower constituency in Westminster had previously also elected only Labour Members of Parliament (MPs) since 1908; the longest run (with Normanton and Makerfield) of any UK constituency. This ended in 2015 when the Conservatives took the seat. In 2017, it returned to Labour. The area of both constituencies covers the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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