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Nanook Dome
Nanook Dome is a rounded mass of rock on the southeastern rim of Mount Edziza's summit crater in northwestern British Columbia, Canada. It has an elevation of , slightly lower than the pinnacles on the southern crater rim which represent the highest points of Mount Edziza. The dome is about in diameter, almost circular in structure and contains steep, smooth convex margins that reach heights of . Its northeastern side is truncated by the headwall of an immense cirque containing Tenchen Glacier, but the current structure of the dome is nevertheless almost identical to its original form. Nanook Dome is one of three lava domes defined as part of the Edziza Formation, which is one of many geological formations comprising the Mount Edziza volcanic complex. The dome consists mainly of trachyte that erupted as viscous lava from a vent on the southwestern rim of Mount Edziza's summit crater. Some of the lava from this vent flowed into the crater where it ponded to form one or more la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Crater
A volcanic crater is an approximately circular depression in the ground caused by volcanic activity. It is typically a bowl-shaped feature containing one or more vents. During volcanic eruptions, molten magma and volcanic gases rise from an underground magma chamber, through a conduit, until they reach the crater's vent, from where the gases escape into the atmosphere and the magma is erupted as lava. A volcanic crater can be of large dimensions, and sometimes of great depth. During certain types of explosive eruptions, a volcano's magma chamber may empty enough for an area above it to subside, forming a type of larger depression known as a caldera. Geomorphology In most volcanoes, the crater is situated at the top of a mountain formed from the erupted volcanic deposits such as lava flows and tephra. Volcanoes that terminate in such a summit crater are usually of a conical form. Other volcanic craters may be found on the flanks of volcanoes, and these are commonly refe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convex
Convex or convexity may refer to: Science and technology * Convex lens, in optics Mathematics * Convex set, containing the whole line segment that joins points ** Convex polygon, a polygon which encloses a convex set of points ** Convex polytope, a polytope with a convex set of points ** Convex metric space, a generalization of the convexity notion in abstract metric spaces * Convex function In mathematics, a real-valued function is called convex if the line segment between any two distinct points on the graph of a function, graph of the function lies above or on the graph between the two points. Equivalently, a function is conve ..., when the line segment between any two points on the graph of the function lies above or on the graph * Convex conjugate, of a function * Convexity (algebraic geometry), a restrictive technical condition for algebraic varieties originally introduced to analyze Kontsevich moduli spaces Economics and finance * Convexity (finance), second ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tahltan
The Tahltan or Nahani are a First Nations people of the Athabaskan-speaking ethnolinguistic group who live in northern British Columbia around Telegraph Creek, Dease Lake, and Iskut. The Tahltan constitute the fourth division of the ''Nahane'' (People of the West). Culture The Tahltan cultural practices and lifeways varied widely as they were often widely separated and would have to endure varying conditions depending on their locality. In Tahltan culture it was believed that some of their ancestors had knowledge that others did not from times before a great flood. Some of these ancestors used that knowledge for the good of the people, while others used it for evil and to the disadvantage of others. Raven is considered to be the protagonist hero against these evil ancestors. Social organization Tahltan social organization is founded on matriarchy and intermarriage between two main clan designations. The two main clans of Tahltan people are Tses' Kiya (pronounced Tses-kee- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geological Survey Of Canada
The Geological Survey of Canada (GSC; , CGC) is a Canadian federal government agency responsible for performing geological surveys of the country developing Canada's natural resources and protecting the environment. A branch of the Earth Sciences Sector of Natural Resources Canada, the GSC is the country's oldest scientific agency and was one of its first government organizations. History In September 1841, the Province of Canada legislature passed a resolution that authorized the sum of £1,500 sterling be granted to the government for the estimated expense of performing a geological survey of the province. In 1842, the Geological Survey of Canada was formed to fulfill this request.Christy Vodden (1992)No Stone Unturned: The First 150 years of the Geological Survey of Canada Geological Survey of Canada Web site William Edmond Logan was in Montreal at the time and made it known that he was interested in participating in this survey. Gaining recommendations from prominent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kakiddi Formation
The Kakiddi Formation is a stratigraphic unit of Pleistocene age in northwestern British Columbia, Canada. Name The Kakiddi Formation is the namesake of Kakiddi Creek, which flows north along the eastern side of the Mount Edziza volcanic complex to the Klastline River. It is also the samesake of Kakiddi Lake where rocks of the Kakiddi Formation are exposed near its western shore. Geology The Kakiddi Formation has a volume of , making it one of the least voluminous of the 13 geological formations comprising the Mount Edziza volcanic complex. It overlies the Ice Peak and Nido formations on the eastern side of Ice Peak and is overlain by the Big Raven Formation at the mouth of Tennaya Creek valley between Nuttlude Lake and Kakiddi Lake. K–Ar dating of the Kakiddi Formation has yielded ages of 0.31 ± 0.07 million years for mugearite, 0.30 ± 0.02 million years for trachyte, 0.29 ± 0.02 million years for Kakiddi feldspar and 0.28 ± 0.2 million years for pantelleritic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lava Lake
Lava lakes are large volumes of molten lava, usually basaltic, contained in a volcanic vent, crater, or broad depression. The term is used to describe both lava lakes that are wholly or partly molten and those that are solidified (sometimes referred to as ''frozen lava lakes''). Formation Lava lakes can form in three ways: *from one or more vents in a crater that erupts enough lava to partially fill the crater; or *when lava pours into a crater or broad depression and partially fills the crater; or *atop a new vent that erupts lava continuously for a period of several weeks or more and slowly builds a crater progressively higher than the surrounding ground. Behaviors Lava lakes occur in a variety of volcanic systems, ranging from the basaltic Erta Ale lake in Ethiopia and the basaltic andesite volcano of Villarrica, Chile, to the unique phonolitic lava lake at Mt. Erebus, Antarctica. Lava lakes have been observed to exhibit a range of behaviours. A "constantly circu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lava
Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fracture in the Crust (geology), crust, on land or underwater, usually at temperatures from . The volcanic rock resulting from subsequent cooling is often also called ''lava''. A lava flow is an outpouring of lava during an effusive eruption. (An explosive eruption, by contrast, produces a mixture of volcanic ash and other fragments called tephra, not lava flows.) The viscosity of most lava is about that of ketchup, roughly 10,000 to 100,000 times that of water. Even so, lava can flow great distances before cooling causes it to solidify, because lava exposed to air quickly develops a solid crust that insulates the remaining liquid lava, helping to keep it hot and inviscid enough to continue flowing. Etymology The word ''lava'' comes from Ital ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trachyte
Trachyte () is an extrusive igneous rock composed mostly of alkali feldspar. It is usually light-colored and aphanite, aphanitic (fine-grained), with minor amounts of mafic minerals, and is formed by the rapid cooling of lava (or shallow intrusions) enriched with silica and alkali metals. It is the volcanic equivalent of syenite. Trachyte is common wherever alkali magma is erupted, including in late stages of ocean island volcanismMacDonald 1983, pp. 51–52 and in continental rift valleys, above mantle plumes,Philpotts and Ague 2009, pp. 390–394 and in areas of back-arc extension. Trachyte has also been found in Gale crater on Mars. Trachyte has been used as decorative building stone and was extensively used as dimension stone in the Roman Empire and the Republic of Venice. Chemical composition Trachyte has a silica content of 60 to 65% and an alkali oxide content of over 7%. This gives it less SiO2 than rhyolite and more (Na2O plus K2O) than dacite. These chemical differe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mount Edziza Volcanic Complex
The Mount Edziza volcanic complex ( ; abbreviated MEVC) is a group of volcanoes and associated lava flows in northwestern British Columbia, Canada. Located on the Tahltan Highland, it is southeast of Telegraph Creek and southwest of Dease Lake. The complex encompasses a broad, steep-sided lava plateau that extends over . Its highest summit is in elevation, making the MEVC the highest of four large complexes in an extensive north–south trending volcanic region. It is obscured by an ice cap characterized by several Glacier morphology#Outlet glaciers, outlet glaciers that stretch out to lower altitudes. The MEVC consists of several types of volcanoes, including stratovolcanoes, shield volcanoes, cinder cones and lava domes. These volcanoes have formed over the last 7.5 million years during five cycles of magmatic activity which spanned four geologic epochs. Volcanic eruptions during these magmatic cycles produced a wide variety of volcanic rocks that comprise 13 geol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geological Formation
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exposed in a geographical region (the stratigraphic column). It is the fundamental unit of lithostratigraphy, the study of strata or rock layers. A formation must be large enough that it can be mapped at the surface or traced in the subsurface. Formations are otherwise not defined by the thickness (geology), thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology (rock type), or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock. The concept of a geologic formation goes back to the beginnings of modern scientific geology. The term was used by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edziza Formation
The Edziza Formation ( ) is a stratigraphic unit of Pleistocene age in northwestern British Columbia, Canada. First described in 1984, the Edziza Formation was mapped as one of several geological formations of the Mount Edziza volcanic complex. It overlies at least four other geological formations of this volcanic complex that differ in age and composition. The main volcanic rock comprising the Edziza Formation is trachyte which was deposited by volcanic eruptions at the end of the third magmatic cycle of the Mount Edziza volcanic complex 0.9 million years ago. Trachyte of the Edziza Formation is in the form of lava flows and pyroclastic rocks that comprise the central stratovolcano of Mount Edziza, as well as lava domes on its summit and flanks. At least four lava lakes ponded inside the summit crater which cooled into four rock units that are exposed in the breached eastern crater rim. These lava lakes overlie rock fragments inside the central volcanic conduit which accompanied ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lava Dome
In volcanology, a lava dome is a circular, mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano. Dome-building eruptions are common, particularly in convergent plate boundary settings. Around 6% of eruptions on Earth form lava domes. The geochemistry of lava domes can vary from basalt (e.g. Semeru, 1946) to rhyolite (e.g. Chaiten, 2010) although the majority are of intermediate composition (such as Santiaguito, dacite-andesite, present day). The characteristic dome shape is attributed to high viscosity that prevents the lava from flowing very far. This high viscosity can be obtained in two ways: by high levels of silica in the magma, or by degassing of fluid magma. Since viscous basaltic and andesitic domes weather fast and easily break apart by further input of fluid lava, most of the preserved domes have high silica content and consist of rhyolite or dacite. Existence of lava domes has been suggested for some domed structures on the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
