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Uriconian
Uriconian rocks are volcanic rocks found in parts of Shropshire, United Kingdom. The name relates to '' Uriconio'', the Latin name for an Iron Age hillfort on the summit of the Wrekin, a hill formed of Uriconian rock. The Uriconian rocks of Shropshire (Wrekin Terrane) are thought to be potentially related to the Longmyndian Supergroup of the Stretton Hills, Shropshire, United Kingdom. Current geological profiling of the terranes suggests that the Uriconian rocks are of Precambrian age (Neoproterozoic Phases 2 and 3).P. J. Brenchley, P. F. Rawson ''The Geology of England and Wales'', 2006, 2nd Ed The Uriconian Rocks outcrop to the southeast of the Long Mynd area of the Welsh Borderland Fault System and beyond the Church Stretton Fault which trends northeast-southwest across the area.W. Compston, A. E. Wright, P. Toghill, ''Dating the Late Precambrian volcanicity of England and Wales, Journal of the Geological Society 2002; v.159; pp 323–339 The Stretton Hills are composed prima ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wrekin Terrane
The Wrekin Terrane is one of five inferred fault bounded terranes that make up the basement rocks of the southern United Kingdom. The other notable geological terranes in the region are the Charnwood Terrane, Fenland Terrane, Cymru Terrane and the Monian Composite Terrane.P. J. Brenchley, P. F. Rawson ''The Geology of England and Wales'', 2006, 2nd Ed The Wrekin Terrane is bounded to the west by the Welsh Borderland Fault System and to the east by the Malvern Lineament. The geological terrane to the west is the Cymru Terrane and to the east is Charnwood Terrane. The majority of rocks in the area are associated with the outcrops that are evident at the faulted boundaries.J. N. Carney, J. M. Horak, et al., ''Precambrian Rocks of England and Wales'', ''Joint Nature Conservation Committee.'' Geological Conservation Review Series 20 Intrusive geology The older rocks of the terrane rest in the Precambrian with younger Cambrian rocks resting unconformably upon them. The Precambrian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Longmyndian Supergroup
The Longmyndian Supergroup is a sequence of Late Precambrian rocks that outcrop between the Pontesford–Linley Fault System and the Church Stretton Fault System in the Welsh Borderland Fault System. The supergroup consists of two major geological groups, the Stretton Group and the overlying Wentnor Group. The rocks are a generally regressive sequence from basinal facies to clastic sedimentation. The rocks are thought to be derived from Uriconian mountains that were formed during the southward subduction of an oceanic plate beneath a continental block (ocean closure). The rocks have since been folded due to fault movements and plunge gently to the south. The Longmyndian rocks were deposited in northeast–southwest trending faulted rift basins. These were deposited on top of the Uriconian volcaniclastic deposits. Subsequent ocean closure squeezed these rocks together to provide sub-vertical bedding in the synclinal sequence we see in exposed rocks today. As noted below, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ercall Hill
The Ercall is a small hill in Shropshire, England, between The Wrekin and Wellington. It is an internationally important geological site, part of The Wrekin and The Ercall Site of Special Scientific Interest (SSSI). The hill is managed by Shropshire Wildlife Trust and includes 540 million year old ripple beds and ancient pre-Cambrian lava flows in exposed quarries. Quartzite from the neighbouring Wrekin is also visible. The Ercall bears the marks of extensive quarrying, although the quarries are now disused, safe and open to the public. When the M54 motorway was constructed in 1974, the road was built through the northern end of the hill. Flora and fauna The woods of the forest are important for various butterfly species. In the summer, the Ercall Woods which line the hill are a favourite habitat for the speckled wood and during spring when the forest is laden with bluebells, the dingy skipper can arrive in great numbers. The exposed quarries are popular with other butterf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Wrekin
The Wrekin is a hill in east Shropshire, England. It is located some five miles (8 km) west of Telford, on the border between the unitary authorities of Shropshire and Telford and Wrekin. Rising above the Shropshire Plain to a height of 407 metres (1,335 feet) above sea level, it is a prominent and well-known landmark, signalling the entrance to Shropshire for travellers westbound on the M54 motorway. The Wrekin is contained within the northern salient of the Shropshire Hills AONB. The hill is popular with walkers and tourists and offers good views of Shropshire. It can be seen well into Staffordshire and the Black Country, and even as far as the Beetham Tower in Manchester, Winter Hill in Lancashire and Cleeve Hill in Gloucestershire. Name The earliest mention of ''the Wrekin'' occurs in a charter of 855, as entered in a late 11th century Worcester cartulary, spelled ''Wreocensetun''. Its modern form is believed to have come into modern English by way of Mercian, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Wrekin
The Wrekin is a hill in east Shropshire, England. It is located some five miles (8 km) west of Telford, on the border between the unitary authorities of Shropshire and Telford and Wrekin. Rising above the Shropshire Plain to a height of 407 metres (1,335 feet) above sea level, it is a prominent and well-known landmark, signalling the entrance to Shropshire for travellers westbound on the M54 motorway. The Wrekin is contained within the northern salient of the Shropshire Hills AONB. The hill is popular with walkers and tourists and offers good views of Shropshire. It can be seen well into Staffordshire and the Black Country, and even as far as the Beetham Tower in Manchester, Winter Hill in Lancashire and Cleeve Hill in Gloucestershire. Name The earliest mention of ''the Wrekin'' occurs in a charter of 855, as entered in a late 11th century Worcester cartulary, spelled ''Wreocensetun''. Its modern form is believed to have come into modern English by way of Mercian, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Rock
Volcanic rock (often shortened to volcanics in scientific contexts) is a rock formed from lava erupted from a volcano. In other words, it differs from other igneous rock by being of volcanic origin. Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and metamorphic rocks and constitute an important element of some sediments and sedimentary rocks. For these reasons, in geology, volcanics and shallow hypabyssal rocks are not always treated as distinct. In the context of Precambrian shield geology, the term "volcanic" is often applied to what are strictly metavolcanic rocks. Volcanic rocks and sediment that form from magma erupted into the air are called "volcaniclastics," and these are technically sedimentary rocks. Volcanic rocks are among the most common rock types on Earth's surface, particularly in the oceans. On land, they are very common at plate boundaries and in flood basalt provinces. It has been estimated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Partial Melting
Partial melting occurs when only a portion of a solid is melted. For mixed substances, such as a rock containing several different minerals or a mineral that displays solid solution, this melt can be different from the bulk composition of the solid. Partial melting occurs where the solidus and liquidus temperatures are different. For single minerals this can happen when they exhibit solid solution, for example in olivines between iron and magnesium. In rocks made up of several different minerals, some will melt at lower temperatures than others. Partial melting of the mantle Melting in the mantle requires one of three possible events to occur: an increase in temperature, a decrease in pressure, or the addition of volatiles to the system (a change in composition). Temperature In the case of raising the temperature, mantle melting will only occur if the mantle is heated past the normal geotherm. It is believed that heat flux from the core and lower mantle is responsible for in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Equator
The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can also be used for any other celestial body that is roughly spherical. In spatial (3D) geometry, as applied in astronomy, the equator of a rotating spheroid (such as a planet) is the parallel (circle of latitude) at which latitude is defined to be 0°. It is an imaginary line on the spheroid, equidistant from its poles, dividing it into northern and southern hemispheres. In other words, it is the intersection of the spheroid with the plane perpendicular to its axis of rotation and midway between its geographical poles. On and near the equator (on Earth), noontime sunlight appears almost directly overhead (no more than about 23° from the zenith) every day, year-round. Consequently, the equator has a rather stable daytime temperature throu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Continental Plate
Continental may refer to: Places * Continent, the major landmasses of Earth * Continental, Arizona, a small community in Pima County, Arizona, US * Continental, Ohio, a small town in Putnam County, US Arts and entertainment * ''Continental'' (album), an album by Saint Etienne * Continental (card game), a rummy-style card game * ''Continental'' (film), a 2013 film * Continental Singers, a Christian music organization Companies * Continental AG, a German automotive parts and technologies manufacturer * Continental Airlines, a former American airline * Continental Electronics, an American radio transmitter manufacturer * Continental Films, a German-controlled French film company during the Nazi occupation of France * Continental Illinois, a defunct large bank * Continental Mortgage and Loan Company (later known as Continental, Inc.), the former name of HomeStreet Bank * Continental Motors, Inc., a Chinese manufacturer of aircraft engines * Continental Records, a former America ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oceanic Plate
Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramafic cumulates. The crust overlies the rigid uppermost layer of the mantle. The crust and the rigid upper mantle layer together constitute oceanic lithosphere. Oceanic crust is primarily composed of mafic rocks, or sima, which is rich in iron and magnesium. It is thinner than continental crust, or sial, generally less than 10 kilometers thick; however, it is denser, having a mean density of about 3.0 grams per cubic centimeter as opposed to continental crust which has a density of about 2.7 grams per cubic centimeter. The crust uppermost is the result of the cooling of magma derived from mantle material below the plate. The magma is injected into the spreading center, which consists mainly of a partly solidified crystal mush derived from ear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Granophyre
Granophyre ( ; from ''granite'' and ''porphyry'') is a subvolcanic rock that contains quartz and alkali feldspar in characteristic angular intergrowths such as those in the accompanying image. The texture is called granophyric. The texture can be similar to micrographic texture and to the coarser graphic intergrowths of quartz and alkali feldspar common in pegmatite. These textures document simultaneous crystallization of quartz and feldspar from a silicate melt at the eutectic point, perhaps in the presence of a water-rich phase. They may also be formed by crystallization when the magma is significantly undercooled, not necessarily under eutectic conditions. Granophyres typically are intrusive rocks that crystallized at shallow depths, and many have compositions similar to those of granites. A common occurrence of granophyre is within layered igneous intrusions dominated by rocks with compositions like that of gabbro. In such occurrences, the granophyre may form as an end pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Back Arc Basin
A back-arc basin is a type of geologic basin, found at some convergent plate boundaries. Presently all back-arc basins are submarine features associated with island arcs and subduction zones, with many found in the western Pacific Ocean. Most of them result from tensional forces, caused by a process known as oceanic trench rollback, where a subduction zone moves towards the subducting plate. Back-arc basins were initially an unexpected phenomenon in plate tectonics, as convergent boundaries were expected to universally be zones of compression. However, in 1970, Dan Karig published a model of back-arc basins consistent with plate tectonics. Structural characteristics Back-arc basins are typically very long and relatively narrow, often thousands of kilometers long while only being a few hundred kilometers wide at most. For back-arc extension to form, a subduction zone is required, but not all subduction zones have a back-arc extension feature. Back-arc basins are found in are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
