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Llewelyn Volcanic Group
The Llewelyn Volcanic Group is an Ordovician lithostratigraphic group (a sequence of rock strata) in Snowdonia, north-west Wales. The name is derived from Carnedd Llewelyn, the highest peak in the Carneddau range where it outcrops. Outcrops The rocks occur across the Snowdon massif and the Carneddau and within the Capel Curig Anticline. Lithology and stratigraphy The Group comprises around 1400m thickness of ash flow tuffs, flow-banded rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral ...s and breccias with a variety of volcaniclastic sediments erupted or sedimented during the Caradocian epoch of the Ordovician period. The Group comprises (in descending order, i.e. oldest last): *Capel Curig Volcanic Formation *Foel Fras Volcanic Formation *Conwy Rhyolite Volcanic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhyolite
Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained ( aphanitic) in texture, but may be porphyritic, containing larger mineral crystals ( phenocrysts) in an otherwise fine-grained groundmass. The mineral assemblage is predominantly quartz, sanidine, and plagioclase. It is the extrusive equivalent to granite. Rhyolitic magma is extremely viscous, due to its high silica content. This favors explosive eruptions over effusive eruptions, so this type of magma is more often erupted as pyroclastic rock than as lava flows. Rhyolitic ash-flow tuffs are among the most voluminous of continental igneous rock formations. Rhyolitic tuff has been extensively used for construction. Obsidian, which is rhyolitic volcanic glass, has been used for tools from prehistoric times to the present day because it can be shaped to an extremely sharp edge. Rhyolitic pumice finds use as an abrasive, in concrete, and as a soil amendment. Description R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nant Ffrancon Formation
The Nant Ffrancon Fermation is a geologic formation in Wales. It preserves fossils A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in ... dating back to the Ordovician period. See also * List of fossiliferous stratigraphic units in Wales References * Geologic formations of Wales Ordovician System of Europe Ordovician Wales {{Wales-stub Fossiliferous stratigraphic units in Wales ... [...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. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. 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 during the Ordovician as it did in the earlier Cambrian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caradoc
Caradoc Vreichvras (; Modern cy, Caradog Freichfras, ) 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 t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capel Curig Anticline
Capel may refer to: People * Capell, surname, includes a list of people with the surnames Capel and Capell *Capel (given name), includes a list of people with the given name Capel Places England * Capel, Kent, a village and civil parish near Tunbridge Wells * Capel, Surrey, a village and civil parish * Capel-le-Ferne, Kent * Capel St Andrew, Suffolk *Capel St Mary, Suffolk * RNAS Capel, a First World War airship station near Folkestone, Kent Australia *Capel, Western Australia *Shire of Capel, Western Australia *Electoral district of Capel, Western Australia, a Legislative Assembly electorate from 2005 to 2008 *Capel River, Western Australia Other uses * HMS ''Capel'', two Royal Navy ships *Cooperativa Agrícola Pisquera Elqui Limitada, the trademark of a Chilean spirits company, that produces pisco and wine See also *Capels, West Virginia Capels is an unincorporated community on the Tug Fork River in McDowell County, West Virginia West Virginia is a state in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snowdon
Snowdon () or (), is the highest mountain in Wales, at an elevation of above sea level, and the highest point in the British Isles outside the Scottish Highlands. It is located in Snowdonia National Park (') in Gwynedd (historic county of Caernarfonshire). On 17 November 2022, the Snowdonia National Park Authority announced they are to use the Welsh name ''Yr Wyddfa'' for ''Snowdon'' and ''Eryri'' for ''Snowdonia'' in all circumstances and capacities, in English and Welsh. It is the busiest mountain in the United Kingdom and the third most visited attraction in Wales; in 2019 it was visited by 590,984 walkers, with an additional 140,000 people taking the train. It is designated as a national nature reserve for its rare flora and fauna. The rocks that form Snowdon were produced by volcanoes in the Ordovician period, and the massif has been extensively sculpted by glaciation, forming the pyramidal peak of Snowdon and the arêtes of Crib Goch and Y Lliwedd. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carneddau
The (lit. 'the cairns'; is a 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 Wales and England (although larger areas over 2,000 feet are found in Northern England), as well as six or seven of the highest peaks in the country—the 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 Conwy valley to the east, and by the A5 road from Betws-y-Coed to 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 (to the north), the A5 to the south and the A470 to the east. Geology In common with much of Snowdonia, the rocks forming the Carneddau originated largely during the Ordovician period between 485 and 444 Ma (million years ago). P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snowdonia
Snowdonia or Eryri (), is a mountainous region in northwestern Wales and a national park of in area. It was the first to be designated of the three national parks in Wales, in 1951. Name and extent It was a commonly held belief that the name is derived from ("eagle"), and thus means "the abode/land of eagles", but recent evidence is that it means ''highlands'', and is related to the Latin (to rise) as leading Welsh scholar Sir proved. The term first appeared in a manuscript in the 9th-century , in an account of the downfall of the semi-legendary 5th-century king (Vortigern). In the Middle Ages, the title ''Prince of Wales and Lord of Snowdonia'' () was used by ; his grandfather used the title ''Prince of north Wales and Lord of Snowdonia.'' The name ''Snowdonia'' derives from '' Snowdon'', the highest mountain in the area and the highest mountain in Wales at . Before the boundaries of the national park were designated, "Snowdonia" was generally used to refer to a s ... [...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 either 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 lithostratigraphic unit consisting of a series of related formations that have been classified together to form a group. Formations are the fundamental unit of stratigraphy. Groups may sometimes be combined into 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 distinguished from its neighbor by its lithology, but all were deposited in the sam ... [...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 the appear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cwm Eigiau Formation
Cwm may refer to: * Cwm (landform), a rounded, glaciated valley, also known as a corrie or cirque * 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 (window manager) or Calm Window Manager, a stacking window manager for Unix systems * Canadian War Museum, Canada's national museum of military history * Cape Wine Master, a South African wine industry qualification * Christian Witness Ministries, a non-denominational church affiliation * Circus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
