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Fan Fraith
Fan Fraith is a top of Fan Gyhirych in the Fforest Fawr section of the Brecon Beacons National Park in the county of Powys, south Wales. Its summit is at a height of 2192 feet or 668 m. It lies within Fforest Fawr Geopark. Geology The bulk of the hill is formed from sandstones and mudstones of the Brownstones Formation of the Old Red Sandstone laid down during the Devonian period. Sandstones of the overlying Plateau Beds Formation occur in the summit area as do beds of the Grey Grits Formation - both are assigned to the upper Devonian. The Plateau Beds sandstones occur across the whole southern aspect of the mountain and are often present as boulder fields,a result of periglacial activity. Several geological fault (geology), faults affect these rocks, the most significant of which is the northeast-southwest aligned Swansea Fault, a part of the Cribarth Disturbance.British Geological Survey 1:50,000 map sheet 231 'Merthyr Tydfil' & accompanying memoir Access The hill is entirely ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foel Fraith
Foel Fraith is a hill in the Black Mountain (range), Black Mountain in the county of Carmarthenshire, southwest Wales. It lies within the Brecon Beacons National Park and Fforest Fawr Geopark. Its plateau-like summit attains a height of above sea level. To the north the subsidiary summit of Cefn y Cylchau reaches , and to the southeast is the subsidiary summit of Carn Fadog or Cefn Carn Fadog, which reaches a height of . Geology The hill has a split personality with its northern slopes dominated by the succession of Carboniferous Limestone rocks and its southern slopes by the Twrch Sandstone (formerly known as the 'Basal Grit') of the overlying Marros Group, but also dating from the Carboniferous period. In common with the Geology of South Wales, regional trend the rock strata dip moderately to the south though locally the beds overlying the limestone have foundered as this soluble rock has dissolved away over millennia. There is an extensive area of shakeholes across the ent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brecon Beacons National Park
The Brecon Beacons National Park ( cy, Parc Cenedlaethol Bannau Brycheiniog) is one of three national parks in Wales, and is centred on the Brecon Beacons range of hills in southern Wales. It includes the Black Mountain ( cy, Y Mynydd Du) in the west, Fforest Fawr (translates as 'great forest') and the Brecon Beacons in the centre and the Black Mountains ( cy, Y Mynydd Du or Mynyddoedd Duon) in the east. Description The Brecon Beacons National Park was established in 1957, the last of the three Welsh parks designated after Snowdonia in 1951 and the Pembrokeshire Coast in 1952. It stretches from Llandeilo in the west to Hay-on-Wye in the northeast and Pontypool in the southeast, covering and encompassing four main regions – the Black Mountain in the west, reaching 802 metres (2631 feet) at Fan Brycheiniog, Fforest Fawr and the Brecon Beacons in the centre, including the highest summit in the park and in South Wales at Pen y Fan 886 metres (2,907 feet) and the confusingly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cribarth Disturbance
The Cribarth Disturbance is a geological structure forming a lineament which stretches across south Wales from Swansea up the Swansea Valley then northeastwards to Brecon and beyond. It consists of both a series of faults and associated folds which were active during the mountain-building period known as the Variscan orogeny. This line of weakness probably featured in the earlier Caledonian Orogeny and perhaps reflects a more ancient line of weakness in the basement rocks. It is also known (in part) as the Tawe Valley Disturbance or the Swansea Valley Disturbance. Influence on the landscape The Disturbance is responsible for a number of significant landscape features along its 50 km length. Prominent amongst these is the Swansea Valley, formed both by glacial action during the ice ages and river erosion along this line of weakness in the Earth's crust between Abercraf and Swansea. It is now occupied by the River Tawe. The geologically complex mountain of Cribarth also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fault (geology)
In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, such as the megathrust faults of subduction zones or transform faults. Energy release associated with rapid movement on active faults is the cause of most earthquakes. Faults may also displace slowly, by aseismic creep. A ''fault plane'' is the plane that represents the fracture surface of a fault. A '' fault trace'' or ''fault line'' is a place where the fault can be seen or mapped on the surface. A fault trace is also the line commonly plotted on geologic maps to represent a fault. A ''fault zone'' is a cluster of parallel faults. However, the term is also used for the zone of crushed rock along a single fault. Prolonged motion along closely spaced faults can bl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Periglacial
Periglaciation (adjective: "periglacial", also referring to places at the edges of glacial areas) describes geomorphic processes that result from seasonal thawing of snow in areas of permafrost, the runoff from which refreezes in ice wedges and other structures. "Periglacial" suggests an environment located on the margin of past glaciers. However, freeze and thaw cycles influence landscapes outside areas of past glaciation. Therefore, periglacial environments are anywhere that freezing and thawing modify the landscape in a significant manner. Tundra is a common ecological community in periglacial areas. History Periglaciation became a distinct subject within the study of geology after Walery Łoziński, a Polish geologist, introduced the term in 1909. Łoziński drew upon the early work of Johan Gunnar Andersson. According to Alfred Jahn, his introduction of his work at the 1910 International Geological Congress held in Stockholm caused significant discussion. In the field tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Devonian Period
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, where rocks from this period were first studied. The first significant adaptive radiation of life on dry land occurred during the Devonian. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents. By the middle of the Devonian, several groups of plants had evolved leaves and true roots, and by the end of the period the first seed-bearing plants appeared. The arthropod groups of myriapods, arachnids and hexapods also became well-established early in this period, after starting their expansion to land at least from the Ordovician period. Fish reached substantial diversity during this time, leading the Devonian to often be dubbed the Age of Fishes. The placoderms began dominating ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Old Red Sandstone
The Old Red Sandstone is an assemblage of rocks in the North Atlantic region largely of Devonian age. It extends in the east across Great Britain, Ireland and Norway, and in the west along the northeastern seaboard of North America. It also extends northwards into Greenland and Svalbard. These areas were a part of the ancient continent of Euramerica/Laurussia. In Britain it is a lithostratigraphic unit (a sequence of rock strata) to which stratigraphers accord supergroup status and which is of considerable importance to early paleontology. For convenience the short version of the term, ORS is often used in literature on the subject. The term was coined to distinguish the sequence from the younger New Red Sandstone which also occurs widely throughout Britain. Sedimentology The Old Red Sandstone describes a suite of sedimentary rocks deposited in a variety of environments during the Devonian but extending back into the late Silurian and on into the earliest part of the ... [...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 distin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) because they are the most resistant minerals to weathering processes at the Earth's surface. Like uncemented sand, sandstone may be any color due to impurities within the minerals, but the most common colors are tan, brown, yellow, red, grey, pink, white, and black. Since sandstone beds often form highly visible cliffs and other topographic features, certain colors of sandstone have been strongly identified with certain regions. Rock formations that are primarily composed of sandstone usually allow the percolation of water and other fluids and are porous enough to store large quantities, making them valuable aquifers and petroleum reservoirs. Quartz-bearing sandstone can be changed into quartzite through metamorphism, usually r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fforest Fawr Geopark
Fforest Fawr Geopark is a Geopark in the Brecon Beacons National Park, south Wales. It is the first designated Geopark in Wales having gained membership of both the European Geoparks Network and the UNESCO-assisted Global Network of National Geoparks in October 2005. The Geopark aims to promote and support sustainable tourism and other opportunities to improve the economy of the area whilst safeguarding the natural environment. Its aims largely coincide with the statutory duties and purpose of the National Park within which it sits. History of designation An initial application to the European Geoparks Network (EGN) made for a more geographically restricted Geopark based on the upper Swansea Valley was turned down in 2003 but the present area which extends to was accepted by the EGN at their meeting in October 2005. A Geopark Development Officer was appointed in January 2007 whilst the National Park Authority also employs an education officer part of whose time is dedicate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fforest Fawr
Fforest Fawr is an extensive upland area in the county of Powys, Wales. Formerly known as the Great Forest of Brecknock in English, it was a royal hunting area for several centuries but is now used primarily for sheep grazing, forestry, water catchment and recreation. It lies within the Brecon Beacons National Park. Extent The area extends from the edge of the Black Mountain in the west eastwards to the A470 Brecon to Merthyr Tydfil road, just west of the Brecon Beacons themselves. It includes the peaks of Fan Fawr (734 m), Fan Frynych (629 m), Craig Cerrig-gleisiad (629 m), Fan Llia (632 m), Fan Nedd (663 m), Fan Gyhirych (725 m), Fan Bwlch Chwyth (603 m) and Cefn Cul (562 m). Traditionally Fforest Fawr also included the peaks of Fan Hir and Fan Brycheiniog, although the modern recreational use of the name tends to be restricted to the area east of the Black Mountain of which they form a part. Geology The area is largely underlain by sandstones and mudstones of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Black Mountain (range)
The Black Mountain ( cy, Y Mynydd Du) is a mountain range in South, Mid and West Wales, straddling the county boundary between Carmarthenshire and Powys (formerly Brecknockshire) and forming the westernmost range of the Brecon Beacons National Park. Its highest point is Fan Brycheiniog at 802 metres or 2,631 ft. The Black Mountain also forms a part of the Fforest Fawr Geopark. Name The Black Mountain should not be confused with the Black Mountains in the east of the National Park, nor with a summit in the Black Mountains that is confusingly also called Black Mountain. In his description of a ''Blak Montayne'', the antiquarian John Leland refers to a massif extending between Carmarthen and Monmouth i.e. what is now considered to be the Brecon Beacons in the wider modern sense of that term, thus also including the Black Mountains and the intervening high ground of Fforest Fawr. The term "Carmarthen Fans" (''Bannau Sir Gâr'' in Welsh) is sometimes used inaccur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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