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Tectonic Block
A tectonic block is a part of the Earth's crust that can be treated as a solid rigid crustal block or lithospheric section. A tectonic block may be bounded by faults. It may move from one place to another because of a tectonic shift, and they may also be rotated. A tectonic block may have a proper name for example, the Muness Phyllite Block (which is located in Unst and Uyea in Scotland), or the South China Block The Yangtze Plate, also called the South China Block or the South China Subplate, comprises the bulk of southern China. It is separated on the east from the Okinawa Plate by a rift that forms the Okinawa Trough which is a back-arc basin, on the so .... Early use of the term tectonic block referred to the blocks of rock on either side of a fault. Continental regions may be subdivided into tectonic blocks which are mapped in order to determine earthquake risk. References Tectonics {{tectonics-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crust (geology)
In geology, the crust is the outermost solid shell of a rocky planet, dwarf planet, or natural satellite. It is usually distinguished from the underlying mantle by its chemical makeup; however, in the case of icy satellites, it may be distinguished based on its phase (solid crust vs. liquid mantle). The crusts of Earth, Mercury, Venus, Mars, Io, the Moon and other planetary bodies formed via igneous processes and were later modified by erosion, impact cratering, volcanism, and sedimentation. Most terrestrial planets have fairly uniform crusts. Earth, however, has two distinct types: continental crust and oceanic crust. These two types have different chemical compositions and physical properties and were formed by different geological processes. Types of crust Planetary geologists divide crust into three categories based on how and when it formed. Primary crust / primordial crust This is a planet's "original" crust. It forms from solidification of a magma ocean. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lithosphere
A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust and the portion of the upper mantle that behaves elastically on time scales of up to thousands of years or more. The crust and upper mantle are distinguished on the basis of chemistry and mineralogy. Earth's lithosphere Earth's lithosphere, which constitutes the hard and rigid outer vertical layer of the Earth, includes the crust and the uppermost mantle. The lithosphere is underlain by the asthenosphere which is the weaker, hotter, and deeper part of the upper mantle. The lithosphere–asthenosphere boundary is defined by a difference in response to stress. The lithosphere remains rigid for very long periods of geologic time in which it deforms elastically and through brittle failure, while the asthenosphere deforms viscously and accommodates strain through plastic deformation. The thickness of the lithosphere is thus considered to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fault (geology)
In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, such as the megathrust faults of subduction zones or transform faults. Energy release associated with rapid movement on active faults is the cause of most earthquakes. Faults may also displace slowly, by aseismic creep. A ''fault plane'' is the plane that represents the fracture surface of a fault. A '' fault trace'' or ''fault line'' is a place where the fault can be seen or mapped on the surface. A fault trace is also the line commonly plotted on geologic maps to represent a fault. A ''fault zone'' is a cluster of parallel faults. However, the term is also used for the zone of crushed rock along a single fault. Prolonged motion along closely spaced faults can blur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unst
Unst (; sco, Unst; nrn, Ønst) is one of the North Isles of the Shetland Islands, Scotland. It is the northernmost of the inhabited British Isles and is the third-largest island in Shetland after Mainland and Yell. It has an area of . Unst is largely grassland, with coastal cliffs. Its main village is Baltasound, formerly the second-largest herring fishing port after Lerwick and now the location of a leisure centre and the island's airport. Other settlements include Uyeasound, home to Greenwell's Booth (a Hanseatic warehouse) and Muness Castle (built in 1598 and sacked by pirates in 1627); and Haroldswick, location of a boat museum and a heritage centre. Etymology There are three island names in Shetland of unknown and possibly pre-Celtic origin: Unst, Fetlar and Yell. The earliest recorded forms of these three names do carry Norse meanings: ''Fetlar'' is the plural of ''fetill'' and means "shoulder-straps", ''Ǫmstr'' is "corn-stack" and ''í Ála'' is from ''ál'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uyea, Unst
Uyea ( sco, Uyea) is an uninhabited island, lying south of Unst in Shetland, Scotland. History The island was inhabited as early as the Bronze Age, and a chambered cairn can still be seen. In the twelfth century, Saint Olaf's chapel overlooking Brei Wick was built. In 1745, two girls from Uyea rowed to the small island of Haaf Gruney to milk some of the cows grazing here. They were caught in a storm when trying to return, and eventually they found their tiny boat blown to Karmøy in south west Norway. The Uyea girls ended up marrying Karmøy men, and their descendants still live there. Jack Priest, in his memoir of the isle during World War II, described it as "a beachcomber's dream - washed as it is with a westerly Atlantic tide through Bluemull Sound, fed from the east by waters of the Norwegian basin and finally the North Sea pressing up from among the isles through the narrow channel between Yell and Fetlar and feeding Colgrave Sound on the south side of Uyea Isle."P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South China Block
The Yangtze Plate, also called the South China Block or the South China Subplate, comprises the bulk of southern China. It is separated on the east from the Okinawa Plate by a rift that forms the Okinawa Trough which is a back-arc basin, on the south by the Sunda Plate and the Philippine Sea Plate, and on the north and west by the Eurasian Plate. The Longmenshan Fault on the latter border was the site of the 2008 Sichuan earthquake, 2008 Wenchuan earthquake. The Yangtze Plate was formed by the disaggregation of the Rodinia Supercontinent 750 million years ago, in the Neoproterozoic era (geology), era. South China rifted away from the Gondwana supercontinent in the Silurian. During the formation of the great supercontinent Pangaea, South China was a smaller, separate continent located off the east coast of the supercontinent and drifting northward. In the Triassic the Yangtze Plate collided with the North China Plate, thereby connecting with Pangaea, and formed the Sichuan basin. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
