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Rhinog Fach And Y Llethr
The Rhinogydd (a Welsh plural form, often anglicised as Rhinogs and also known by the alternative Welsh plural Rhinogau) are a range of mountains located east of Harlech in North Wales. The name ''Rhinogydd'' derives from the names of two of the more famous peaks, Rhinog Fawr and Rhinog Fach, although the greatest elevation in the range is reached by Y Llethr, 756 m (2,480 feet). Foel Penolau, the northernmost summit of the range, was promoted to a Hewitt in 2018 due to a new survey. The Rhinogydd are notably rocky and heather-clad towards the northern end of the range, especially around Rhinog Fawr, Rhinog Fach and towards Moel Ysgyfarnogod. The southern end, around Y Llethr, Diffwys and the Ysgethin Valley has a softer, grassy character. A population of feral goats are in the range. Over 30 km² are protected as a Special Area of Conservation and a National Nature Reserve. Geology The Rhinogydd are formed of hard sedimentary rocks of Cambrian age which occur as a major a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Welsh Language
Welsh ( or ) is a Celtic language family, Celtic language of the Brittonic languages, Brittonic subgroup that is native to the Welsh people. Welsh is spoken natively in Wales, by some in England, and in Y Wladfa (the Welsh colony in Chubut Province, Argentina). Historically, it has also been known in English as "British", "Cambrian", "Cambric" and "Cymric". The Welsh Language (Wales) Measure 2011 gave the Welsh language official status in Wales. Both the Welsh and English languages are ''de jure'' official languages of the Welsh Parliament, the Senedd. According to the 2021 United Kingdom census, 2021 census, the Welsh-speaking population of Wales aged three or older was 17.8% (538,300 people) and nearly three quarters of the population in Wales said they had no Welsh language skills. Other estimates suggest that 29.7% (899,500) of people aged three or older in Wales could speak Welsh in June 2022. Almost half of all Welsh speakers consider themselves fluent Welsh speakers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Special Area Of Conservation
A Special Area of Conservation (SAC) is defined in the European Union's Habitats Directive (92/43/EEC), also known as the ''Directive on the Conservation of Natural Habitats and of Wild Fauna and Flora''. They are to protect the 220 habitats and approximately 1,000 species listed in annex I and II of the directive which are considered to be of European interest following criteria given in the directive. They must be chosen from the Sites of Community Importance by the member states and designated SAC by an act assuring the conservation measures of the natural habitat. SACs complement Special Protection Areas and together form a network of protected sites across the European Union called Natura 2000. This, in turn, is part of the Emerald network of Areas of Special Conservation Interest (ASCIs) under the Berne Convention. Assessment methodology in the United Kingdom Prior to being designated as a Special Area of Conservation (SAC), sites have been assessed under a two-stage process ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dike (geology)
A dike or dyke, in Geology, geological usage, is a sheet of rock that is formed in a Fracture (geology), fracture of a pre-existing rock body. Dikes can be either Intrusive rock, magmatic or Sedimentary rock, sedimentary in origin. Magmatic dikes form when magma flows into a crack then solidifies as a sheet intrusion, either cutting across layers of rock or through a contiguous mass of rock. Clastic dikes are formed when sediment fills a pre-existing crack.Essentials of Geology, 3rd Ed, Stephen Marshak Magmatic dikes A magmatic dike is a sheet of igneous rock that cuts across older rock beds. It is formed when magma fills a fracture in the older beds and then cools and solidifies. The dike rock is usually more resistant to weathering than the surrounding rock, so that erosion exposes the dike as a natural wall or ridge. It is from these natural walls that dikes get their name. Dikes preserve a record of the fissures through which most mafic magma (fluid magma low in silica) reac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dolerite
Diabase (), also called dolerite () or microgabbro, is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine-grained to aphanitic chilled margins which may contain tachylite (dark mafic glass). ''Diabase'' is the preferred name in North America, while ''dolerite'' is the preferred name in the rest of the English-speaking world, where sometimes the name ''diabase'' refers to altered dolerites and basalts. Some geologists prefer to avoid confusion by using the name ''microgabbro''. The name ''diabase'' comes from the French ', and ultimately from the Greek - meaning "act of crossing over, transition". Petrography Diabase normally has a fine but visible texture of euhedral lath-shaped plagioclase crystals (62%) set in a finer matrix of clinopyroxene, typically augite (20–29%), with minor olivine (3% up to 12% in olivine diabase), magnetite (2%), and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mudstone
Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology.'' New York, New York, W. H. Freeman, 2nd ed, 529 pp. The term ''mudstone'' is also used to describe carbonate rocks (limestone or dolomite) that are composed predominantly of carbonate mud. However, in most contexts, the term refers to siliciclastic mudstone, composed mostly of silicate minerals. The NASA Curiosity rover has found deposits of mudstone on Mars that contain organic substances such as propane, benzene and toluene. Definition There is not a single definition of mudstone that has gained general acceptance,Boggs 2006, p.143 though there is wide agreement that mudstones are fine-grained sedimentary rocks, composed mostly of silicate grains with a grain size less than . Individual grains this size are too small to be disting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siltstone
Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, pp.381-382 Although its permeability and porosity is relatively low, siltstone is sometimes a tight gas reservoir rock, an unconventional reservoir for natural gas that requires hydraulic fracturing for economic gas production. Siltstone was prized in ancient Egypt for manufacturing statuary and cosmetic palettes. The siltstone quarried at Wadi Hammamat was a hard, fine-grained siltstone that resisted flaking and was almost ideal for such uses. Description There is not complete agreement on the definition of siltstone. One definition is that siltstone is mudrock ( clastic sedimentary rock containing at least 50% clay and silt) in which at least 2/3 of the clay and silt fraction is composed of silt-sized particles. Silt is defined a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greywacke
Greywacke or graywacke (German ''grauwacke'', signifying a grey, earthy rock) is a variety of sandstone generally characterized by its hardness, dark color, and poorly sorted angular grains of quartz, feldspar, and small rock fragments or lithic fragments set in a compact, clay-fine matrix. It is a texturally immature sedimentary rock generally found in Paleozoic strata. The larger grains can be sand- to gravel-sized, and matrix materials generally constitute more than 15% of the rock by volume. The term "greywacke" can be confusing, since it can refer to either the immature (rock fragment) aspect of the rock or its fine-grained (clay) component. The origin of greywacke was unknown until turbidity currents and turbidites were understood, since, according to the normal laws of sedimentation, gravel, sand and mud should not be laid down together. Geologists now attribute its formation to submarine avalanches or strong turbidity currents. These actions churn sediment and cause mi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blaenau Ffestiniog
Blaenau Ffestiniog is a town in Gwynedd, Wales. Once a slate mining centre in historic Merionethshire, it now relies much on tourists, drawn for instance to the Ffestiniog Railway and Llechwedd Slate Caverns. It reached a population of 12,000 at the peak development of the slate industry, but fell with the decline in demand for slate. The population of the community, including the nearby village Llan Ffestiniog, was 4,875 in the 2011 census: the fourth most populous in Gwynedd after Bangor, Caernarfon and Llandeiniolen. The population not including Llan is now only about 4,000. Etymology and pronunciation The meaning of Blaenau Ffestiniog is "uplands of Ffestiniog". The Welsh word ' is the plural of ' "upland, remote region". Ffestiniog here is probably "territory of Ffestin" (Ffestin being a personal name) or could possibly mean "defensive place". The English pronunciation of Blaenau Ffestiniog suggested by the ''BBC Pronouncing Dictionary of British Names'' is , but the f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cadair Idris
Cadair Idris or Cader Idris is a mountain in the Meirionnydd area of Gwynedd, Wales. It lies at the southern end of the Snowdonia National Park near the town of Dolgellau. The peak, which is one of the most popular in Wales for walkers and hikers, is composed largely of Ordovician igneous rocks, with classic glacial erosion features such as cwms, moraines, striated rocks, and roches moutonnées. Etymology ''Cadair Idris'' means 'Idris's Chair'. Idris is usually taken to be the name of a giant or, alternatively, it may refer to Idris ap Gwyddno (or Gweiddno), a 7th-century prince of Meirionnydd who won a battle against the Irish on the mountain. Idris ap Gwyddno was in fact referred to as ''Idris Gawr'' ("Idris the Giant") in some mediaeval genealogies of Meirionydd. The basic meaning of the word ''cadair'' (Middle Welsh/Early Modern Welsh ''kadeir'' or ''cadeir'') is 'seat, chair' (borrowed from the Greek ''cathedra'' 'chair'). In place names ''cadair'' can mean 'stronghold, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caledonian Orogeny
The Caledonian orogeny was a mountain-building era recorded in the northern parts of the British Isles, the Scandinavian Mountains, Svalbard, eastern Greenland and parts of north-central Europe. The Caledonian orogeny encompasses events that occurred from the Ordovician to Early Devonian, roughly 490–390 million years ago ( Ma). It was caused by the closure of the Iapetus Ocean when the continents and terranes of Laurentia, Baltica and Avalonia collided. The orogeny is named for Caledonia, the Latin name for Scotland. The term was first used in 1885 by Austrian geologist Eduard Suess for an episode of mountain building in northern Europe that predated the Devonian period. Geologists like Émile Haug and Hans Stille saw the Caledonian event as one of several episodic phases of mountain building that had occurred during Earth's history. Current understanding has it that the Caledonian orogeny encompasses a number of tectonic phases that can laterally be diachronous. The n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harlech Dome
The Harlech Dome is a geological dome in southern Snowdonia in north Wales. It extends approximately from Blaenau Ffestiniog in the north to Tywyn in the south, and includes Harlech, The Rhinogydd, Barmouth and Cadair Idris. The geological layer structure comprises Cambrian sedimentary, volcanic and intrusive rocks from the lower Paleozoic age approximately 4.5 km thick. The geology contains the Harlech Grits Group, Mawddach Group, Rhobell Volcanic Group and Aran Volcanic Group. The area contains a wide range of metallic minerals and has been mined for (copper, silver, zinc, manganese, gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile met ...) in the past. References Rock formations of Gwynedd {{UK-geology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anticline
In structural geology, an anticline is a type of fold that is an arch-like shape and has its oldest beds at its core, whereas a syncline is the inverse of an anticline. A typical anticline is convex up in which the hinge or crest is the location where the curvature is greatest, and the limbs are the sides of the fold that dip away from the hinge. Anticlines can be recognized and differentiated from antiforms by a sequence of rock layers that become progressively older toward the center of the fold. Therefore, if age relationships between various rock strata are unknown, the term antiform should be used. The progressing age of the rock strata towards the core and uplifted center, are the trademark indications for evidence of anticlines on a geologic map. These formations occur because anticlinal ridges typically develop above thrust faults during crustal deformations. The uplifted core of the fold causes compression of strata that preferentially erodes to a deeper st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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