|
Snowdon Volcanic Group
The Snowdon Volcanic Group is an Ordovician lithostratigraphic group (a sequence of rock strata) in Snowdonia, north-west Wales. The name is derived from Snowdon, the highest peak in Wales where it outcrops. This assemblage of rocks has also been referred to as the Snowdon Volcanic Series. Outcrops The rocks occur across the Snowdon massif and to its south, southeast and west, around the eastern flanks of the Carneddau and within the Idwal syncline. Lithology and stratigraphy The Group consists of up to 1800 m thickness of ash flow tuffs with sandstones, mudstones and siltstones and important basalt, hyaloclastites and breccias erupted or sedimented during the Caradoc Caradoc Vreichvras (; Modern , ) was a semi-legendary ancestor to the kings of Gwent. He may have lived during the 5th or 6th century. He is remembered in the Matter of Britain as a Knight of the Round Table, under the names King Carados and C ...ian Epoch of the Ordovician Period. The Group includes (in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Y Lliwedd
Y Lliwedd is a mountain, connected to Snowdon in the Snowdonia National Park, North Wales. Its summit lies above sea level. The eastern flanks are steep cliffs rising above Glaslyn and Llyn Llydaw. Y Lliwedd is the most conspicuous of the peaks for those who approach Snowdon via the Miners' and Pyg tracks. Few that summit Snowdon continue over to Y Lliwedd as the challenge of Wales' highest peak is enough, leaving Y Lliwedd quiet and peaceful even when queues are forming at the summit of Snowdon. Hikers and mountaineers often pass over Y Lliwedd when walking the Snowdon Horseshoe. The noted British climber George Mallory undertook many of his early climbs here. It was also the site of considerable training activity for the 1953 British Everest Expedition. The north face of Y Lliwedd was explored in the late 19th century and in 1909 was the subject of the first British climbing guide, ''The Climbs on Lliwedd'' by J. M. A. Thomson and A. W. Andrews. Two subsidiary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lithostratigraphy
Lithostratigraphy is a sub-discipline of stratigraphy, the geological science associated with the study of strata or rock layers. Major focuses include geochronology, comparative geology, and petrology. In general, strata are primarily igneous or sedimentary relating to how the rock was formed. Sedimentary layers are laid down by deposition of sediment associated with weathering processes, decaying organic matter (biogenic) or through chemical precipitation. These layers are often distinguishable as having many fossils and are important for the study of biostratigraphy. Igneous layers occur as stacks of lava flows, layers of lava fragments (called tephra) both erupted onto the Earth's surface by volcanoes, and in layered intrusions formed deep underground. Igneous layers are generally devoid of fossils and represent magmatic or volcanic activity that occurred during the geologic history of an area. There are a number of principles that are used to explain relationships betwe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ordovician System Of Europe
The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era, and the second of twelve periods of the Phanerozoic Eon. The Ordovician spans 41.6 million years from the end of the Cambrian Period Ma (million years ago) to the start of the Silurian Period Ma. The Ordovician, named after the Welsh tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same rock beds in North Wales in the Cambrian and Silurian systems, respectively. Lapworth recognized that the fossil fauna in the disputed strata were different from those of either the Cambrian or the Silurian systems, and placed them in a system of their own. The Ordovician received international approval in 1960 (forty years after Lapworth's death), when it was adopted as an official period of the Paleozoic Era by the International Geological Congress. Life continued to flourish ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caradoc
Caradoc Vreichvras (; Modern , ) was a semi-legendary ancestor to the kings of Gwent. He may have lived during the 5th or 6th century. He is remembered in the Matter of Britain as a Knight of the Round Table, under the names King Carados and Carados Briefbras (French for "Carados Shortarm"). Identification and historicity Though the name "Caradoc" and its various forms were by no means uncommon during the Middle Ages, it is probable some of the Caradocs referred to in Welsh genealogies and hagiographies such the ''Life of St. Tatheus'' are the same person. Due to the name's prevalence considerable confusion exists about Caradoc's identity, both historical and literary. He may have become confused with the British hero Caratacus (the Latin form of Caradoc), Cerdic of Wessex and any number of British history's later Caradocs. His parentage varies from text to text; he is called the son of Llŷr Marini (possibly implying Llŷr) several times in the ''Mabinogion'', and a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Breccia
Breccia ( , ; ) is a rock composed of large angular broken fragments of minerals or Rock (geology), rocks cementation (geology), cemented together by a fine-grained matrix (geology), matrix. The word has its origins in the Italian language, in which it means "rubble". A breccia may have a variety of different origins, as indicated by the named types including sedimentary breccia, fault (geology), fault or tectonics, tectonic breccia, igneous breccia, Impact event, impact breccia, and Hydrothermal circulation, hydrothermal breccia. A megabreccia is a breccia composed of very large rock fragments, sometimes kilometers across, which can be formed by landslides, impact events, or caldera collapse. Types Breccia is composed of coarse rock fragments held together by cement or a fine-grained matrix. Like Conglomerate (geology), conglomerate, breccia contains at least 30 percent of gravel-sized particles (particles over 2mm in size), but it is distinguished from Conglomerate (geol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sandstone
Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar, because they are the most resistant minerals to the weathering processes at the Earth's surface. Like uncemented sand, sandstone may be imparted any color by impurities within the minerals, but the most common colors are tan, brown, yellow, red, grey, pink, white, and black. Because sandstone beds can form highly visible cliffs and other topography, topographic features, certain colors of sandstone have become strongly identified with certain regions, such as the red rock deserts of Arches National Park and other areas of the Southwestern United States, American Southwest. Rock formations composed of sandstone usually allow the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cwm Idwal
Cwm Idwal is a cirque (or corrie) in the Glyderau range of mountains in northern Snowdonia, the national park in the mountainous region of North Wales. Its main interest is to hill walkers and rock climbers, but it is also of interest to geologists and naturalists, given its combination of altitude (relatively high in UK terms), aspect (north-facing) and terrain (mountainous and rocky). In a 2005 poll conducted by ''Radio Times'', Cwm Idwal was ranked the 7th greatest natural wonder in Britain. Geology Cwm Idwal is a spectacular product of glaciation, surrounded by high crags, screes, moraines and rounded rocks, with a lake on its floor ( Llyn Idwal). Cwm Idwal comprises volcanic and sedimentary rock which was laid down in a shallow Ordovician sea, and later folded to give rise to the distinctive trough-shaped arrangement of strata known today as the Idwal Syncline. This fold in the rock is visible today, thanks to the layering of the sedimentary rocks. The area was then erode ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carneddau
The (lit. 'the cairns'; is a Welsh language, Welsh plural form, and is sometimes anglicised to ''Carnedds'') are a group of mountains in Snowdonia, Wales. They include the largest contiguous areas of high ground (over or high) in England and Wales, Wales and England (although larger areas over are found in Northern England), as well as six or seven of the highest peaks in the country—the Welsh 3000s, Fifteen Peaks. The range also encloses a number of lakes such as Llyn Cowlyd and Llyn Eigiau, and the Aber Falls waterfall. It is delimited by the Irish Sea to the north, the River Conwy, Conwy valley to the east, and by the A5 road (Great Britain), A5 road from Betws-y-Coed to Bethesda, Gwynedd, Bethesda to the south and west. The area covers nearly , about 10% of the area of Snowdonia. The area is bordered by three main roads—the A55 road, A55 (to the north), the A5 road (Great Britain), A5 to the south and the A470 road, A470 to the east. Geology In common with Geology of S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snowdonia
Snowdonia, or Eryri (), is a mountainous region and National parks of the United Kingdom, national park in North Wales. It contains all 15 mountains in Wales Welsh 3000s, over 3000 feet high, including the country's highest, Snowdon (), which is tall. These peaks are all part of the Snowdon Massif, Snowdon, Glyderau, and Carneddau ranges in the north of the region. The shorter Moelwynion and Moel Hebog ranges lie immediately to the south. The national park has an area of (the fourth-largest in the UK), and covers most of central and southern Gwynedd and the western part of Conwy County Borough. This is much larger than the area traditionally considered Snowdonia, and in addition to the five ranges above includes the Rhinogydd, Cadair Idris, and Aran Fawddwy, Aran ranges and the Dyfi hills, Dyfi Hills. It also includes most of the coast between Porthmadog and Aberdyfi. The park was the first of the three national parks of Wales to be designated, in October 1951, and the third i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rock Strata
In geology and related fields, a stratum (: strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as either '' bedding surfaces'' or ''bedding planes''.Salvador, A. ed., 1994. ''International stratigraphic guide: a guide to stratigraphic classification, terminology, and procedure. 2nd ed.'' Boulder, Colorado, The Geological Society of America, Inc., 215 pp. . Prior to the publication of the International Stratigraphic Guide, older publications have defined a stratum as being either equivalent to a single bed or composed of a number of beds; as a layer greater than 1 cm in thickness and constituting a part of a bed; or a general term that includes both ''bed'' and ''lamina''.Neuendorf, K.K.E., Mehl, Jr., J.P., and Jackson, J.A. , eds., 2005. ''Glossary of Geology'' 5th ed. Alexandria, Virginia, American Geological Institute. 779 pp. . ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Group (stratigraphy)
In geology, a group is a lithostratigraphy, lithostratigraphic Stratigraphic unit, unit consisting of a series of related Geological formation, formations that have been classified together to form a group. Formations are the fundamental unit of stratigraphy. Groups may sometimes be combined into Supergroup (geology), supergroups. Groups are useful for showing relationships between formations, and they are also useful for small-scale mapping or for studying the stratigraphy of large regions. Geologists exploring a new area have sometimes defined groups when they believe the strata within the groups can be divided into formations during subsequent investigations of the area. It is possible for only some of the strata making up a group to be divided into formations. An example of a group is the Glen Canyon Group, which includes (in ascending order) the Wingate Sandstone, the Moenave Formation, the Kayenta Formation, and the Navajo Sandstone. Each of the formations can be distingui ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cwm Eigiau Formation
Cwm or cŵm may refer to: * Cwm (landform), a rounded, glaciated valley, also known as a corrie or cirque * Cwm, a steep, narrow valley, or a small valley or large hollow on the side of a hill, also known as a combe * Cwm (software), a general-purpose data processor for the semantic web * Cwm railway station, a station in Cwm, Blaenau Gwent, Wales, 1852–1963 * Cwm Rhondda, a famous Welsh hymn tune Places * Cwm, Blaenau Gwent, a community in Wales * Cwm, Llanrothal, a Jesuit gathering place in Herefordshire, England * Cwm, Denbighshire, a community in Wales * Cwm Cadnant, a community in Anglesey, north Wales * Cwm Gwaun, a community in northern Pembrokeshire, Wales * Cwm Penmachno, a community in Snowdonia, north Wales * Western Cwm, a geographical feature on Mount Everest Abbreviations CWM may refer to: * cwm (window manager) or Calm Window Manager, a stacking window manager for Unix systems * Canadian War Museum, Canada's national museum of military history * Christian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
