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Pen Allt-mawr
Pen Allt-mawr is a high subsidiary summit of Waun Fach and the third highest peak in the Black Mountains in south-eastern Wales. A very recognisable and prominent peak of the Black Mountains, it lies near the end of the more westerly of Waun Fach's two broad southern ridges. Its top Pen Twyn Glas is to the north, while its close neighbour Pen Cerrig-calch is to the south. A prominent spur 1 km to the SSW of the summit is known as Pen Gloch-y-pibwr. The stepped Bryniog ridge curves southward from this point. Its summit is stony and has damaged Bronze Age cairns and a large shelter cairn together with a trig point. Further Bronze Age cairns are found along the western edge of the plateau to the south. Geology The summit of Pen Allt-mawr is at the northern tip of a broadly triangular summit surface formed from a slab of southerly tilting upper Old Red Sandstone traditionally known as the Quartz Conglomerate. These rocks which date from the Late Devonian Epoch are co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pen Cerrig-calch
Pen Cerrig-calch is a subsidiary summit of Waun Fach in the Black Mountains in the Brecon Beacons National Park in southern Powys, Wales. Its summit, at a height of 701 m (2,300 ft), is marked by a trig point. The peak sits high above the River Usk valley as it narrows above the small town of Crickhowell. The views from here are wide-ranging and extend as far as the Beacons themselves to the west. A ridge runs off to the northwest and the shoulder of Pen Gloch-y-pibwr then turns north to the secondary top of Pen Allt-mawr whose peak at 719m is also crowned by a trig point. Geology Like all of the hills in the Black Mountains, Pen Cerrig-calch is formed from mudstones and sandstones of the Old Red Sandstone laid down during the Devonian period but it is unusual in having a band of Carboniferous Limestone outcropping around the summit and giving rise to a few shakeholes. A classic example of an outlier, the name of the hill reflects this situation; it means 'top of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trig Point
A triangulation station, also known as a trigonometrical point, and sometimes informally as a trig, is a fixed surveying station, used in geodetic surveying and other surveying projects in its vicinity. The nomenclature varies regionally: they are generally known as trigonometrical stations or triangulation stations in North America, trig points in the United Kingdom, trig pillars in Ireland, trig stations or trig points in Australia and New Zealand, and trig beacons in South Africa. Use The station is usually set up by a government with known coordinates and elevation published. Many stations are located on hilltops for the purposes of visibility. A graven metal plate on the top of a pillar may provide a mounting point for a theodolite or reflector, often using some form of kinematic coupling to ensure reproducible positioning. Trigonometrical stations are grouped together to form a network of triangulation. Positions of all land boundaries, roads, railways, bridges and other ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuttalls
Nuttall may refer to: People * Nuttall (name) * Nuttall baronets Nature * Nuttall's oak, a fast-growing large deciduous oak tree native to North America * Nuttall's woodpecker, a species of woodpecker found in oak woodlands of California * Nuttall sandstone, a very hard type of sandstone; see New River Gorge National River * Nuttall's toothwort, a species of cardamine flower. Places * Nuttall, Virginia, United States * Nuttall railway station, Nuttall village, Nasirabad, Balochistan, Pakistan * Nuttalls, hills in England and Wales that are over with a prominence above Other uses * BAM Nuttall, a British construction company * Blackman–Nuttall window, a mathematical function used in signal processing—see Window function * Codex Zouche-Nuttall, a pre-Columbian piece of Mixtec writing * Geiger–Nuttall law, a rule in nuclear physics stating that short-lived isotopes emit more energetic alpha particles than long-lived ones * Nuttall Ornithological Club, the oldest ornitho ... [...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] |
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 related to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sugar Loaf, Monmouthshire
Sugar Loaf, sometimes called The Sugar Loaf ( cy, Mynydd Pen-y-fâl or ), is a hill situated north-west of Abergavenny in Monmouthshire, Wales and sits within the Brecon Beacons National Park. It is the southernmost of the summit peaks of the Black Mountains, with a height of 1,955 feet (596 metres). Sugar Loaf was gifted to the National Trust by suffragette Lady Rhondda. Name The original Welsh name of the hill appears to have been Mynydd Pen-y-fâl. Translated into English, this name means 'mountain of the head/top of the peak/summit' from ''mynydd'', ''pen'' and ''bâl''. The name Sugar Loaf has been popularly applied to numerous hills which have a perceived resemblance to a sugarloaf; the nearest other such hill is the Sugar Loaf, Carmarthenshire. Prehistory A southern foothill of Sugar Loaf, ''Y Graig'', was discovered in the 1990s to be the site of prehistoric flint tools dating from the Mesolithic, Neolithic and Bronze Ages. Geology It is a popular m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inliers And Outliers (geology)
An inlier is an area of older rocks surrounded by younger rocks. Inliers are typically formed by the erosion of overlying younger rocks to reveal a limited exposure of the older underlying rocks. Faulting or folding may also contribute to the observed outcrop pattern. A classic example from Great Britain is that of the inlier of folded Ordovician and Silurian rocks at Horton in Ribblesdale in North Yorkshire which are surrounded by the younger flat-lying Carboniferous Limestone. The location has long been visited by geology students and experts. Another example from South Wales is the Usk Inlier in Monmouthshire where Silurian age rocks are upfolded amidst Old Red Sandstone rocks of Devonian age. A similar outcrop pattern which results from movement on a thrust fault followed by erosion may be termed a window. Conversely an outlier is an area of younger rock surrounded by older rocks. An outlier is typically formed when sufficient erosion of surrounding rocks has taken place to s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Devonian
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, Euramerica/Laurussia. In Britain it is a lithostratigraphy, lithostratigraphic unit (a sequence of rock strata) to which Stratigraphy, stratigraphers accord Geological unit#Lithostratigraphic units, 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bronze Age
The Bronze Age is a historic period, lasting approximately from 3300 BC to 1200 BC, characterized by the use of bronze, the presence of writing in some areas, and other early features of urban civilization. The Bronze Age is the second principal period of the three-age system proposed in 1836 by Christian Jürgensen Thomsen for classifying and studying ancient societies and history. An ancient civilization is deemed to be part of the Bronze Age because it either produced bronze by smelting its own copper and alloying it with tin, arsenic, or other metals, or traded other items for bronze from production areas elsewhere. Bronze is harder and more durable than the other metals available at the time, allowing Bronze Age civilizations to gain a technological advantage. While terrestrial iron is naturally abundant, the higher temperature required for smelting, , in addition to the greater difficulty of working with the metal, placed it out of reach of common use until the end o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Waun Fach
Waun Fach is, with a summit height of , the highest mountain in the Black Mountains in south-eastern Wales. It is one of the three Marilyns over 600 m that make up the range, the others being Black Mountain and Mynydd Troed. To the north Rhos Fawr and the Radnor Forest can be seen. It is the third highest mountain in Britain south of Snowdonia (after Pen y Fan and its near neighbour Corn Du). It is situated at the head of the Grwyne Fechan valley, above and to the west of the Grwyne Fawr reservoir. It has an undistinguished (and almost indistinguishable) rounded summit. The nearby tops on the ridge, Pen Trumau and Pen y Gadair Fawr, although lower, are very much more recognisable. Geology The summit and upper slopes of Waun Fach are formed from the Early Devonian Epoch sandstones of the Brownstones Formation, a division of the Old Red Sandstone. Beneath these and forming the lower slopes are the sandstones of the Senni Formation (traditionally the Senni Bed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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