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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] [Amazon] |
Big Raven Plateau
The Big Raven Plateau is an intermontane plateau in Cassiar Land District of northwestern British Columbia, Canada. It lies on the Tahltan Highland and is surrounded by several valleys, including those of Mess Creek, Kakiddi Creek, Chakima Creek, Walkout Creek and the Klastline River. The plateau is drained by many small streams that flow into these neighbouring valleys and, unlike the valleys, it is relatively barren vegetation, barren of vegetation. Stream erosion has resulted in the creation of canyons with intervening ridges on the eastern and western sides of the plateau, resulting in the creation of rugged terrain. The plateau is in Mount Edziza Provincial Park which is one of the largest provincial parks in British Columbia. Access to the Big Raven Plateau is mainly by aircraft or by a network of horse trails from surrounding roads. The Big Raven Plateau is volcanic plateau, volcanic in origin, consisting mostly of basaltic lava flows of the Mount Edziza volcanic complex t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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] [Amazon] |
Glacier Morphology
Glacier morphology, or the form a glacier takes, is influenced by temperature, precipitation, topography, and other factors. The goal of glacial morphology is to gain a better understanding of glaciated landscapes and the way they are shaped. Types of glaciers can range from massive ice sheets, such as the Greenland ice sheet, to small cirque glaciers found perched on mountain tops. Glaciers can be grouped into two main categories: * Ice flow is constrained by the underlying bedrock topography * Ice flow is unrestricted by surrounding topography Unconstrained Glaciers Ice sheets and ice caps Ice sheets and ice caps cover the largest areas of land in comparison to other glaciers, and their ice is unconstrained by the underlying topography. They are the largest glacial ice formations and hold the vast majority of the world's fresh water. Ice sheets Ice sheets are the largest form of glacial formation. They are continent-sized ice masses that span areas over . They are dome ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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 By definition, ice caps are not constrained by topographical features (i.e., they must 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 significantly affect the geomorphology of the area 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. The Antarctic and Greenland contain 99% of the ice volume on earth, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
