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Hoodoo Mountain
Hoodoo Mountain, sometimes referred to as Hoodoo Volcano, is a potentially active stratovolcano in the Northern Interior of British Columbia, Canada. It is located northeast of the Alaska–British Columbia border on the north side of the Iskut River opposite of the mouth of the Craig River. With a summit elevation of and a topographic prominence of , Hoodoo Mountain is one of many prominent peaks within the Boundary Ranges of the Coast Mountains. Its flat-topped summit is covered by an ice cap more than thick and at least in diameter. Two valley glaciers surrounding the northwestern and northeastern sides of the mountain have retreated significantly over the last hundred years. They both originate from a large icefield to the north and are the sources of two meltwater streams. These streams flow along the western and eastern sides of the volcano before draining into the Iskut River. Much of Hoodoo Mountain was formed beneath glacial ice and it has been overlain by glacier ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iskut River
The Iskut River, located in the northwest part of the province of British Columbia is the largest tributary of the Stikine River, entering it about above its entry into Alaska. From its source at Kluachon Lake the Iskut River flows south and west for about Length measured using BCGNIS coordinates, topographic maps, anToporama/ref> to the Stikine River near the border of British Columbia and Alaska. The upper Iskut flows south through a series of lakes: Kluachon Lake, Eddontenajon Lake, Tatogga Lake, Kinaskan Lake, Natadesleen Lake, and others. The middle Iskut encompasses the area between the Little Iskut River and Forrest Kerr Creek. Below the Ningunsaw River the Iskut flows southwest through a canyon and is regulated by the Forrest Kerr Hydroelectric Project, a run-of-river hydroelectric project. The lower Iskut flows west through an increasingly braided channel. The upper Iskut is in the Klastline Plateau, a subregion of the Stikine Plateau. The middle Iskut forms the bou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stratovolcano
A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and periodic intervals of explosive eruptions and effusive eruptions, although some have collapsed summit craters called calderas. The lava flowing from stratovolcanoes typically cools and hardens before spreading far, due to high viscosity. The magma forming this lava is often felsic, having high-to-intermediate levels of silica (as in rhyolite, dacite, or andesite), with lesser amounts of less-viscous mafic magma. Extensive felsic lava flows are uncommon, but have travelled as far as . Stratovolcanoes are sometimes called composite volcanoes because of their composite stratified structure, built up from sequential outpourings of erupted materials. They are among the most common types of volcanoes, in contrast to the less common shield volca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Explosive Eruption
In volcanology, an explosive eruption is a volcanic eruption of the most violent type. A notable example is the 1980 eruption of Mount St. Helens. Such eruptions result when sufficient gas has dissolved under pressure within a viscous magma such that expelled lava violently froths into volcanic ash when pressure is suddenly lowered at the vent. Sometimes a lava plug will block the conduit to the summit, and when this occurs, eruptions are more violent. Explosive eruptions can expel as much as per second of rocks, dust, gas and pyroclastic material, averaged over the duration of eruption, that travels at several hundred meters per second as high as into the atmosphere. This cloud may subsequently collapse, creating a fast-moving pyroclastic flow of hot volcanic matter. Stages of an explosive eruption An explosive eruption begins with some form of blockage in the crater of a volcano that prevents the release of gases trapped in highly viscous andesitic or rhyolitic magma. The pr ... [...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 moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or underwater, usually at temperatures from . The volcanic rock resulting from subsequent cooling is also often 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. The word ''lava'' comes from Italian and is probably derived from the Latin word ''labes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phonolite
Phonolite is an uncommon extrusive rock, of intermediate chemical composition between felsic and mafic, with texture ranging from aphanitic (fine-grained) to porphyritic (mixed fine- and coarse-grained). Phonolite is a variation of the igneous rock trachyte that contains nepheline or leucite rather than quartz. Its intrusive equivalent is nepheline syenite. Phonolite is typically fine grained and compact. The name ''phonolite'' comes from the Ancient Greek meaning "sounding stone" due to the metallic sound it produces if an unfractured plate is hit; hence, the English name ''clinkstone'' is given as a synonym. Formation Unusually, phonolite forms from magma with a relatively low silica content, generated by low degrees of partial melting (less than 10%) of highly aluminous rocks of the lower crust such as tonalite, monzonite and metamorphic rocks. Melting of such rocks to a very low degree promotes the liberation of aluminium, potassium, sodium and calcium by melting of f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcano
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates are diverging or converging, and most are found underwater. For example, a mid-ocean ridge, such as the Mid-Atlantic Ridge, has volcanoes caused by divergent tectonic plates whereas the Pacific Ring of Fire has volcanoes caused by convergent tectonic plates. Volcanoes can also form where there is stretching and thinning of the crust's plates, such as in the East African Rift and the Wells Gray-Clearwater volcanic field and Rio Grande rift in North America. Volcanism away from plate boundaries has been postulated to arise from upwelling diapirs from the core–mantle boundary, deep in the Earth. This results in hotspot volcanism, of which the Hawaiian hotspot is an example. Volcanoes are usually not created where two tectonic plates slide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meltwater
Meltwater is water released by the melting of snow or ice, including glacial ice, tabular icebergs and ice shelves over oceans. Meltwater is often found in the ablation zone of glaciers, where the rate of snow cover is reducing. Meltwater can be produced during volcanic eruptions Several types of volcanic eruptions—during which lava, tephra (ash, lapilli, volcanic bombs and volcanic blocks), and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often ..., in a similar way in which the more dangerous lahars form. When meltwater pools on the surface rather than flowing, it forms melt ponds. As the weather gets colder meltwater will often re-freeze. Meltwater can collect or melt under the ice's surface. These pools of water, known as subglacial lakes can form due to geothermal heat and friction. Water source Meltwater provides drinking water for a large proportion of the world's population, as well as pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Icefield
An ice field (also spelled icefield) is a mass of interconnected valley glaciers (also called mountain glaciers or alpine glaciers) on a mountain mass with protruding rock ridges or summits. They are often found in the colder climates and higher altitudes of the world where there is sufficient precipitation for them to form. The higher peaks of the underlying mountain rock that protrude through the icefields are known as nunataks. Ice fields are larger than alpine glaciers, but smaller than ice caps and ice sheets. The topography of ice fields is determined by the shape of the surrounding landforms, while ice caps have their own forms overriding underlying shapes. Formation Ice fields are formed by a large accumulation of snow which, through years of compression and freezing, turns into ice. Due to ice's susceptibility to gravity, ice fields usually form over large areas that are basins or atop plateaus, thus allowing a continuum of ice to form over the landscape uninterrupted b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Valley Glacier
A valley is an elongated low area often running between hills or mountains, which will typically contain a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers or streams over a very long period. Some valleys are formed through erosion by glacial ice. These glaciers may remain present in valleys in high mountains or polar areas. At lower latitudes and altitudes, these glacially formed valleys may have been created or enlarged during ice ages but now are ice-free and occupied by streams or rivers. In desert areas, valleys may be entirely dry or carry a watercourse only rarely. In areas of limestone bedrock, dry valleys may also result from drainage now taking place underground rather than at the surface. Rift valleys arise principally from earth movements, rather than erosion. Many different types of valleys are described by geographers, using terms that may be global in use or else applied only locally. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ice Cap
In glaciology, an ice cap is a mass of ice that covers less than of land area (usually covering a highland area). Larger ice masses covering more than are termed ice sheets. Description Ice caps are not constrained by topographical features (i.e., they will lie over the top of mountains). By contrast, ice masses of similar size that ''are'' constrained by topographical features are known as ice fields. The ''dome'' of an ice cap is usually centred on the highest point of a massif. Ice flows away from this high point (the ice divide) towards the ice cap's periphery. Ice caps have significant effects on the geomorphology of the area that they occupy. Plastic moulding, gouging and other glacial erosional features become present upon the glacier's retreat. Many lakes, such as the Great Lakes in North America, as well as numerous valleys have been formed by glacial action over hundreds of thousands of years. On Earth, there are about of total ice mass. The average temperature ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coast Mountains
The Coast Mountains (french: La chaîne Côtière) are a major mountain range in the Pacific Coast Ranges of western North America, extending from southwestern Yukon through the Alaska Panhandle and virtually all of the Coast of British Columbia south to the Fraser River. The mountain range's name derives from its proximity to the sea coast, and it is often referred to as the Coast Range. The range includes volcanic and non-volcanic mountains and the extensive ice fields of the Pacific and Boundary Ranges, and the northern end of the volcanic system known as the Cascade Volcanoes. The Coast Mountains are part of a larger mountain system called the Pacific Coast Ranges or the Pacific Mountain System, which includes the Cascade Range, the Insular Mountains, the Olympic Mountains, the Oregon Coast Range, the California Coast Ranges, the Saint Elias Mountains and the Chugach Mountains. The Coast Mountains are also part of the American Cordilleraa Spanish term for an extensive chain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Topographic Prominence
In topography, prominence (also referred to as autonomous height, relative height, and shoulder drop in US English, and drop or relative height in British English) measures the height of a mountain or hill's summit relative to the lowest contour line encircling it but containing no higher summit within it. It is a measure of the independence of a summit. A peak's ''key col'' (the highest col surrounding the peak) is a unique point on this contour line and the ''parent peak'' is some higher mountain, selected according to various criteria. Definitions The prominence of a peak may be defined as the least drop in height necessary in order to get from the summit to any higher terrain. This can be calculated for a given peak in the following way: for every path connecting the peak to higher terrain, find the lowest point on the path; the ''key col'' (or ''key Saddle point, saddle'', or ''linking col'', or ''link'') is defined as the highest of these points, along all connecting pat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
