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Tindar (landform)
Tindar is a ridge made by subglacial volcanism. It can contain pillow lava, pillow breccia, hyalotuff, hyaloclastite. Examples are Skefilfjall, Kálfstindar, Helgafell in Iceland and Pillow Ridge in British Columbia British Columbia (commonly abbreviated as BC) is the westernmost Provinces and territories of Canada, province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include ..., Canada. References {{volcano-stub Volcanology Ridges ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ridge
A ridge or a mountain ridge is a geographical feature consisting of a chain of mountains or hills that form a continuous elevated crest for an extended distance. The sides of the ridge slope away from the narrow top on either side. The lines along the crest formed by the highest points, with the terrain dropping down on either side, are called the ridgelines. Ridges are usually termed hills or mountains as well, depending on size. Smaller ridges, especially those leaving a larger ridge, are often referred to as spurs. Types There are several main types of ridges: ;Dendritic ridge: In typical dissected plateau terrain, the stream drainage valleys will leave intervening ridges. These are by far the most common ridges. These ridges usually represent slightly more erosion resistant rock, but not always – they often remain because there were more joints where the valleys formed or other chance occurrences. This type of ridge is generally somewhat random in orientation, oft ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subglacial Eruption
Subglacial eruptions, those of ice-covered volcanoes, result in the interaction of magma with ice and snow, leading to meltwater formation, jökulhlaups, and lahars. Flooding associated with meltwater is a significant hazard in some volcanic areas, including Iceland, Alaska, and parts of the Andes. Jökulhlaups (glacial outburst floods) have been identified as the most frequently occurring volcanic hazard in Iceland, with major events where peak discharges of meltwater can reach 10,000 – 100,000 m3/s occurring when there are large eruptions beneath glaciers. It is important to explore volcano-ice interactions to improve the effectiveness of monitoring these events and to undertake hazard assessments. This is particularly relevant given that subglacial eruptions have demonstrated their ability to cause widespread impact, with the ash cloud associated with Iceland's Eyjafjallajökull eruption in 2010 resulting in significant impacts to aviation across Europe. Examp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pillow Lava
Pillow lavas are lavas that contain characteristic pillow-shaped structures that are attributed to the extrusion of the lava underwater, or ''subaqueous extrusion''. Pillow lavas in volcanic rock are characterized by thick sequences of discontinuous pillow-shaped masses, commonly up to one meter in diameter. They form the upper part of Layer 2 of normal oceanic crust. Composition Pillow lavas are commonly of basaltic composition, although pillows formed of komatiite, picrite, boninite, basaltic andesite, andesite, dacite or even rhyolite are known. In general, the more felsic the composition (richer in silica - resulting in an Intermediate composition), the larger the pillows, due to the increase in viscosity of the erupting lava. Occurrence They occur wherever lava is extruded underwater, such as along marine hotspot volcano chains and the constructive plate boundaries of mid-ocean ridges. As new oceanic crust is formed, thick sequences of pillow lavas are erupted at the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pillow Breccia
A pillow is a support of the body at rest for comfort, therapy, or decoration. Pillows are used in different variations by many species, including humans. Some types of pillows include throw pillows, body pillows, decorative pillows, and many more. Pillows that aid sleeping are a form of bedding that supports the head and neck. Other types of pillows are designed to support the body when lying down or sitting. There are also pillows that consider human body shape for increased comfort during sleep. Decorative pillows used on people, couches or chairs are sometimes referred to as cushions. In contemporary western culture, pillows consist of a plain or patterned fabric envelope (known as a pillowcase) which contains a soft stuffing, typically synthetic and typically standardized in sizes and shape. Pillows have been historically made of a variety of natural materials and many cultures continue to use pillows made from natural materials in the world. The word ''pillow'' comes f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyalotuff
Phreatomagmatic eruptions are volcanic eruptions resulting from interaction between magma and water. They differ from exclusively magmatic eruptions and phreatic eruptions. Unlike phreatic eruptions, the products of phreatomagmatic eruptions contain juvenile (magmatic) clasts.Heiken, G. & Wohletz, K. 1985. Volcanic Ash. University of California Press, Berkeley It is common for a large explosive eruption to have magmatic and phreatomagmatic components. Mechanisms Several competing theories exist as to the exact mechanism of ash formation. The most common is the theory of explosive thermal contraction of particles under rapid cooling from contact with water. In many cases the water is supplied by the sea, for example with Surtsey. In other cases the water may be present in a lake or caldera-lake, for example Santorini, where the phreatomagmatic component of the Minoan eruption was a result of both a lake and later the sea. There have also been examples of interaction between magma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyaloclastite
Hyaloclastite is a volcanoclastic accumulation or breccia consisting of glass (from the Greek ''hyalus'') fragments (clasts) formed by quench fragmentation of lava flow surfaces during submarine or subglacial extrusion. It occurs as thin margins on the lava flow surfaces and between pillow lavas as well as in thicker deposits, more commonly associated with explosive, volatile-rich eruptions as well as steeper topography. Hyaloclastites form during volcanic eruptions under water, under ice or where subaerial flows reach the sea or other bodies of water. It commonly has the appearance of angular flat fragments sized between a millimeter to few centimeters. The fragmentation occurs by the force of the volcanic explosion, or by thermal shock and spallation during rapid cooling. Several mineraloids are found in hyaloclastite masses. Sideromelane is a basalt glass rapidly quenched in water. It is transparent and pure, lacking the iron oxide crystals dispersed in the more commonly oc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helgafell (Hafnarfjörður)
Helgafell () is a mountain on Reykjanes peninsula, Iceland. The height of the mountain is 338 m. Name Many mountains in Iceland bear the name of ''Helgafell''. It means “''holy mountain''” and is thought that in the Viking era, these mountains played a special – if unknown – role in the worship of their gods.Ari Trausti Guðmundsson, Pétur Þorsteinsson: Íslensk fjöll. Gönguleiðir á 152 tind. Reykjavík 2004, p. 98 An architect from Reykjavík measured out the positions of the very old cairn on top of Helgafell as well as the cairns of two other mountains in the vicinity and came to the conclusion that by using the positions of the sun as well as the shades of the cairns, the Vikings had constructed a calendar. Subglacial volcano The mountain is a hyaloclastite ridge formed during the Weichselian glaciation of the Pleistocene epoch. Its typical form shows well as there is not much vegetation on its slopes. Helgafell is located in a tectonically and volcani ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iceland
Iceland ( is, Ísland; ) is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which (along with its surrounding areas) is home to over 65% of the population. Iceland is the biggest part of the Mid-Atlantic Ridge that rises above sea level, and its central volcanic plateau is erupting almost constantly. The interior consists of a plateau characterised by sand and lava fields, mountains, and glaciers, and many glacial rivers flow to the sea through the lowlands. Iceland is warmed by the Gulf Stream and has a temperate climate, despite a high latitude just outside the Arctic Circle. Its high latitude and marine influence keep summers chilly, and most of its islands have a polar climate. According to the ancient manuscript , the settlement of Iceland began in 874 AD when the Norwegian chieftain Ingólfr Arnarson became the first ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pillow Ridge
Pillow Ridge is a ridge of the Tahltan Highland in northern British Columbia, Canada, located southeast of Telegraph Creek. It extends northwest from Mount Edziza in Mount Edziza Provincial Park. History As its name suggests, Pillow Ridge was named on January 2, 1980 by the Geological Survey of Canada for the classic exposures of subaqueous pillow lava that form the ridge. Geology Pillow Ridge is a volcanic feature associated with the Mount Edziza volcanic complex which in turn form part of the Northern Cordilleran Volcanic Province. It is a subglacial mound that formed in the Pleistocene period when this area was buried beneath glacial ice during the last ice age. See also * List of volcanoes in Canada * List of Northern Cordilleran volcanoes * Volcanism of Canada * Volcanism of Western Canada Volcanism of Western Canada has produced lava flows, lava plateaus, lava domes, cinder cones, stratovolcanoes, shield volcanoes, greenstone belts, submarine volcanoes, cald ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
British Columbia
British Columbia (commonly abbreviated as BC) is the westernmost Provinces and territories of Canada, province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, forests, lakes, mountains, inland deserts and grassy plains, and borders the province of Alberta to the east and the Yukon and Northwest Territories to the north. With an estimated population of 5.3million as of 2022, it is Canada's Population of Canada by province and territory, third-most populous province. The capital of British Columbia is Victoria, British Columbia, Victoria and its largest city is Vancouver. Vancouver is List of census metropolitan areas and agglomerations in Canada, the third-largest metropolitan area in Canada; the 2021 Canadian census, 2021 census recorded 2.6million people in Metro Vancouver Regional District, Metro Vancouver. The First Nations in Canada, first known human inhabi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanology
Volcanology (also spelled vulcanology) is the study of volcanoes, lava, magma and related geological, geophysical and geochemical phenomena (volcanism). The term ''volcanology'' is derived from the Latin word '' vulcan''. Vulcan was the ancient Roman god of fire. A volcanologist is a geologist who studies the eruptive activity and formation of volcanoes and their current and historic eruptions. Volcanologists frequently visit volcanoes, especially active ones, to observe volcanic eruptions, collect eruptive products including tephra (such as ash or pumice), rock and lava samples. One major focus of enquiry is the prediction of eruptions; there is currently no accurate way to do this, but predicting eruptions, like predicting earthquakes, could save many lives. Modern volcanology Volcanologist examining tephra horizons in south-central Iceland. In 1841, the first volcanological observatory, the Vesuvius Observatory, was founded in the Kingdom of the Two Sicil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
