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Wenlock (Silurian)
The Wenlock Epoch (sometimes referred to as the Wenlockian) is the second epoch of the Silurian. It is preceded by the Llandovery Epoch and followed by the Ludlow Epoch. Radiometric dates constrain the Wenlockian between and million years ago. Naming and history The Wenlock is named after Wenlock Edge, an outcrop of rocks near the town of Much Wenlock in Shropshire ( West Midlands, United Kingdom). The name was first used in the term "Wenlock and Dudley rocks" by Roderick Murchison in 1834 to refer to the limestones and underlying shales that underlay what he termed the "Ludlow rocks". He later modified this term to simply the "Wenlock rocks" in his book, ''The Silurian System'' in 1839. Definition and subdivision The Wenlock's beginning is defined by the lower boundary (or GSSP) of the Sheinwoodian. The end is defined as the base (or GSSP A Global Boundary Stratotype Section and Point (GSSP), sometimes referred to as a golden spike, is an internationally agreed upo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Commission On Stratigraphy
The International Commission on Stratigraphy (ICS), sometimes unofficially referred to as the International Stratigraphic Commission, is a daughter or major subcommittee grade scientific organization that concerns itself with stratigraphy, stratigraphical, geology, geological, and chronology, geochronological matters, worldwide. It is the largest subordinate body of the International Union of Geological Sciences (IUGS). The ICS is essentially a permanent working committee, working subcommittee, which meets far more regularly than the quadrennial meetings scheduled by the IUGS, when it meets as a congress or committee, membership of the whole. Aims One of its main aims, a project begun in 1974, is to establish a multidisciplinary standard and global geologic time scale that will ease paleontology, paleontological and geobiology, geobiological comparisons region to region by benchmarks with stringent and rigorous strata criteria called Global Boundary Stratotype Section and Points ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Much Wenlock
Much Wenlock is a market town and Civil parishes in England, parish in Shropshire, England; it is situated on the A458 road between Shrewsbury and Bridgnorth. Nearby, to the north-east, is the Ironbridge Gorge and Telford. The civil parish includes the villages of Homer, Shropshire, Homer ( north of the town), Wyke, Shropshire, Wyke ( north-east), Atterley ( south-east), Stretton Westwood ( south-west) and Bourton, Shropshire, Bourton ( south-west). The population of the civil parish, according to the 2001 United Kingdom Census, 2001 Census, was 2,605, increasing to 2,877 by 2011 United Kingdom Census, 2011. Notable historic attractions in the town are Wenlock Priory, Wenlock Edge, Holy Trinity Church and the Guildhall. The Wenlock Olympian Society Annual Games, Wenlock Olympian Games, established by William Penny Brookes in 1850, are centred in the town. Brookes is credited as a founding father of the modern Olympic Games and one of the Wenlock and Mandeville, London 2012 Summe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silurian Geochronology
The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of the Paleozoic Era, and the third of twelve periods of the Phanerozoic Eon. As with other geologic periods, the rock beds that define the period's start and end are well identified, but the exact dates are uncertain by a few million years. The base of the Silurian is set at a series of major Ordovician–Silurian extinction events when up to 60% of marine genera were wiped out. One important event in this period was the initial establishment of terrestrial life in what is known as the Silurian-Devonian Terrestrial Revolution: vascular plants emerged from more primitive land plants, dikaryan fungi started expanding and diversifying along with glomeromycotan fungi, and three groups of arthropods (myriapods, arachnids and hexapods) became full ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wenlock Epoch
The Wenlock Epoch (sometimes referred to as the Wenlockian) is the second epoch of the Silurian. It is preceded by the Llandovery Epoch and followed by the Ludlow Epoch. Radiometric dates constrain the Wenlockian between and million years ago. Naming and history The Wenlock is named after Wenlock Edge, an outcrop of rocks near the town of Much Wenlock in Shropshire ( West Midlands, United Kingdom). The name was first used in the term "Wenlock and Dudley rocks" by Roderick Murchison in 1834 to refer to the limestones and underlying shales that underlay what he termed the "Ludlow rocks". He later modified this term to simply the "Wenlock rocks" in his book, ''The Silurian System'' in 1839. Definition and subdivision The Wenlock's beginning is defined by the lower boundary (or GSSP) of the Sheinwoodian. The end is defined as the base (or GSSP A Global Boundary Stratotype Section and Point (GSSP), sometimes referred to as a golden spike, is an internationally agreed upo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homerian
In the geologic timescale, the Homerian is an age of the Wenlock Epoch of the Silurian Period of the Paleozoic Era of the Phanerozoic Eon that is comprehended between 430.5 ± 0.7 Ma and 427.4 ± 0.5 Ma (million years ago), approximately. The Homerian Age succeeds the Sheinwoodian Age and precedes the Gorstian Age. The name comes from the small village of Homer, Shropshire near Much Wenlock. The defining lower boundary of Homerian rock layers (GSSP A Global Boundary Stratotype Section and Point (GSSP), sometimes referred to as a golden spike, is an internationally agreed upon reference point on a stratigraphic section which defines the lower boundary of a stage on the geologic time scale. ...) is located within the Coalbrookdale Formation of England. References Wenlock epoch Silurian geochronology {{geochronology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gorstian
In the geologic timescale, the Gorstian is an age of the Ludlow Epoch of the Silurian Period of the Paleozoic Era of the Phanerozoic Eon that is comprehended between 427.4 ± 0.5 Ma and 425.6 ± 0.9 Ma (million years ago), approximately. The Gorstian Age succeeds the Homerian Age and precedes the Ludfordian Age. The age is named after Gorsty village southwest of Ludlow Ludlow ( ) is a market town and civil parish in Shropshire (district), Shropshire, England. It is located south of Shrewsbury and north of Hereford, on the A49 road (Great Britain), A49 road which bypasses the town. The town is near the conf .... The base of the age is marked by '' Saetograptus (Colonograptus) varians''. The type section is located in a quarry in the Elton Formation at Pitch Coppice, Shropshire, United Kingdom. References Ludlow epoch Silurian geochronology {{geochronology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sheinwoodian
In the geologic timescale, the Sheinwoodian is the age of the Wenlock Epoch of the Silurian Period of the Paleozoic Era of the Phanerozoic Eon that is comprehended between 433.4 ± 0.8 Ma and 430.5 ± 0.7 Ma (million years ago), approximately. The Sheinwoodian Age succeeds the Telychian Age and precedes the Homerian Age. Definition The Wenlock-Llandovery boundary is defined by the first occurrence of '' Cyrtograptus centrifugus''. The stage is named after Sheinwood village, north of Much Wenlock Much Wenlock is a market town and Civil parishes in England, parish in Shropshire, England; it is situated on the A458 road between Shrewsbury and Bridgnorth. Nearby, to the north-east, is the Ironbridge Gorge and Telford. The civil parish incl .... The Buildwas Formation of Shropshire, United Kingdom contains the type section. References Wenlock epoch Silurian geochronology {{geochronology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GSSP
A Global Boundary Stratotype Section and Point (GSSP), sometimes referred to as a golden spike, is an internationally agreed upon reference point on a stratigraphic section which defines the lower boundary of a stage on the geologic time scale. The effort to define GSSPs is conducted by the International Commission on Stratigraphy, a part of the International Union of Geological Sciences. Most, but not all, GSSPs are based on paleontological changes. Hence GSSPs are usually described in terms of transitions between different faunal stages, though far more faunal stages have been described than GSSPs. The GSSP definition effort commenced in 1977. As of 2024, 79 of the 101 stages that need a GSSP have a ratified GSSP. Rules A geologic section has to fulfill a set of criteria to be adapted as a GSSP by the ICS. The following list summarizes the criteria: * A GSSP has to define the lower boundary of a geologic stage. * The lower boundary has to be defined using a primary m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shale
Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of Clay mineral, clay minerals (hydrous aluminium phyllosilicates, e.g., Kaolinite, kaolin, aluminium, Al2Silicon, Si2Oxygen, O5(hydroxide, OH)4) and tiny fragments (silt-sized particles) of other minerals, especially quartz and calcite.Blatt, Harvey and Robert J. Tracy (1996) ''Petrology: Igneous, Sedimentary and Metamorphic'', 2nd ed., Freeman, pp. 281–292 Shale is characterized by its tendency to split into thin layers (Lamination (geology), laminae) less than one centimeter in thickness. This property is called ''Fissility (geology), fissility''. Shale is the most common sedimentary rock. The term ''shale'' is sometimes applied more broadly, as essentially a synonym for mudrock, rather than in the narrower sense of clay-rich fissile mudrock. Texture Shale typically exhibits varying degrees of fissility. Because of the parallel orientation of clay mineral flakes in shale, it breaks in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limestone
Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science), crystal forms of calcium carbonate . Limestone forms when these minerals Precipitation (chemistry), precipitate out of water containing dissolved calcium. This can take place through both biological and nonbiological processes, though biological processes, such as the accumulation of corals and shells in the sea, have likely been more important for the last 540 million years. Limestone often contains fossils which provide scientists with information on ancient environments and on the evolution of life. About 20% to 25% of sedimentary rock is carbonate rock, and most of this is limestone. The remaining carbonate rock is mostly Dolomite (rock), dolomite, a closely related rock, which contains a high percentage of the mineral Dolomite (mine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Roderick Murchison
Sir Roderick Impey Murchison, 1st Baronet (19 February 1792 – 22 October 1871) was a Scottish geologist who served as director-general of the British Geological Survey from 1855 until his death in 1871. He is noted for investigating and describing the Silurian, Devonian and Permian systems. Early life and work Murchison was born at Tarradale House, Muir of Ord, Ross-shire, the son of Barbara and Kenneth Murchison. His wealthy father died in 1796, when Roderick was four years old, and he was sent to Durham School three years later and then to the Royal Military College, Great Marlow, to be trained for the army. In 1808, under Wellesley, he landed in Portugal, and was present at the actions of Roliça and Vimeiro in the Peninsular War as an ensign in the 36th Regt of Foot. Subsequently, under Sir John Moore, he took part in the retreat to Corunna and the final battle there. After eight years of service Murchison left the army and married Charlotte Hugonin (1788–1869 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dudley
Dudley ( , ) is a market town in the West Midlands, England, southeast of Wolverhampton and northwest of Birmingham. Historically part of Worcestershire, the town is the administrative centre of the Metropolitan Borough of Dudley. In the 2011 census, it had a population of 79,379. The wider Metropolitan Borough had a population of 312,900. In 2014, the borough council adopted a slogan describing Dudley as the capital of the Black Country, a title by which it had long been informally known. Originally a market town, Dudley was one of the birthplaces of the Industrial Revolution and grew into an industrial centre in the 19th century with its iron, coal, and limestone industries before their decline and the relocation of its commercial centre to the nearby Merry Hill Shopping Centre in the 1980s. Tourist attractions include Dudley Zoo and Castle, the 12th century priory ruins, and the Black Country Living Museum. History Early history Dudley has a history dating b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
