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Þjórsá Lava
The Great Þjórsá Lava ( Icelandic: ''Þjórsárhraunið mikla'' ) is the largest lava flow in Iceland (by both area and volume) and the largest lava flow that is known to have erupted in a single eruption in the Holocene. Þjórsá Lava has a total volume of more than , covering approximately . The Þjórsá Lava does not appear on the surface until downstream of its identified eruptive area. Geography In the lowlands of South Iceland the lava has overflown wide areas, covering the districts Landsveit, Gnúpverjahreppur, Skeið and Flói. The main rivers of South Iceland, Þjórsá and HvÃtá/Ölfusá, stream along the borders of the lava to the east and west and the long beach between the river mouths is formed by the lava. The sea level seems to have been around lower than today when the lava was erupted. Along with the rising sea level the ocean has transgressed the lava front so its border line is submerged several hundreds of metres off-shore and its littoral zo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Great Thjorsa Lava
Great may refer to: Descriptions or measurements * Great, a relative measurement in physical space, see Size * Greatness, being divine, majestic, superior, majestic, or transcendent People * List of people known as "the Great" * Artel Great (born 1981), American actor * Great Osobor (born 2002), Spanish-born British basketball player Other uses * ''Great'' (1975 film), a British animated short about Isambard Kingdom Brunel * ''Great'' (2013 film), a German short film * Great (supermarket), a supermarket in Hong Kong * GReAT, Graph Rewriting and Transformation, a Model Transformation Language * Gang Resistance Education and Training, or GREAT, a school-based and police officer-instructed program * Global Research and Analysis Team (GReAT), a cybersecurity team at Kaspersky Lab *'' Great!'', a 2018 EP by Momoland *Great! TV, British TV channel group * ''The Great'' (TV series), an American comedy-drama See also * * * * * The Great (other) The Great is the moniker ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tungnaá Lavas
The Tungnaá () is a river in the southern Highlands of Iceland. It flows from the western edge of Vatnajökull to the reservoir Sultartangalón, where it joins the Þjórsá. The river has been used extensively for hydroelectricity, with power stations at Vatnsfell, Sigalda, Hrauneyjafoss, and Sultartangi. See also *List of rivers of Iceland
On an island like Iceland, the rivers are short in length. None of the rivers are important as a means of navigation due to the impracticality of settlements in the Highlands of Iceland where they originate.
South
* HvÃtá
* Krossá
* ...
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Holocene Volcanism
The Holocene () is the current geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene together form the Quaternary period. The Holocene is an interglacial period within the ongoing glacial cycles of the Quaternary, and is equivalent to Marine Isotope Stage 1. The Holocene correlates with the last maximum axial tilt towards the Sun of the Earth's obliquity. The Holocene corresponds with the rapid proliferation, growth, and impacts of the human species worldwide, including all of its written history, technological revolutions, development of major civilizations, and overall significant transition towards urban living in the present. The human impact on modern-era Earth and its ecosystems may be considered of global significance for the future evolution of living species, including approximately synchronous lithospheric evidence, or more rece ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
East Volcanic Zone Of Iceland
The geological deformation of Iceland is the way that the rocks of the island of Iceland are changing due to tectonic forces. The geological deformation help to explain the location of earthquakes, volcanoes, fissures, and the shape of the island. Iceland is the largest landmass () situated on an oceanic ridge. It is an elevated plateau of the sea floor, situated at the crossing of the Mid-Atlantic Ridge and the Greenland-Iceland-Scotland ridge. It lies along an oceanic divergent plate boundary: the western part of Iceland sits on the North American Plate and the eastern part sits on the Eurasian Plate. The Reykjanes Ridge of the Mid-Atlantic ridge system in this region crosses the island from southwest and connects to the Kolbeinsey Ridge in the northeast. Iceland is geologically young: all rocks there were formed within the last 25 million years. It started forming in the Early Miocene sub-epoch, but the oldest rocks found at the surface of Iceland are from the Middle Miocene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skerry
A skerry ( ) is a small rocky island, or islet, usually too small for human habitation. It may simply be a rocky reef. A skerry can also be called a low stack (geology), sea stack. A skerry may have vegetative life such as moss and small, hardy grasses. They are often used as resting places by animals such as Pinniped, seals and seabird, birds. Etymology The term ''skerry'' is derived from the Old Norse ', which means a small rocky island in the sea (which in turn derives from the Proto-Indo-European root *''sker''-, "cut", in the sense of a rock cut off from the land). The Old Norse term ' was brought into the English language via the Scots language word spelled or . It is a cognate of the Scandinavian languages' words for ''skerry'' – Icelandic language, Icelandic, , , , , found also in , , , , and (). In Scottish Gaelic, it appears as ', e.g. Sula Sgeir, in Irish language, Irish as '','' in Welsh language, Welsh as '','' and in Manx language, Manx as ''.'' Formatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bárðarbunga
Bárðarbunga (, alternative name Veiðivötn), is an active and productive stratovolcano located under Vatnajökull in Vatnajökull National Park which is Iceland's most extensive glacier. The second highest mountain in Iceland, above sea level, Bárðarbunga is also part of the Bárðarbunga-Veiðivötn volcanic system that is approximately long and wide. Bárðarbunga erupted in late August 2014, the eruption style effusive, which is common in Iceland, but had not been seen for a few years. Lava covered the surrounding landscape northwest of the Vatnajökull glacier. Description Bárðarbunga is a subglacial stratovolcano and central volcano under the ice cap of Vatnajökull glacier in the Vatnajökull National Park in Iceland. It is one of the six volcanic systems under Vatnajökull. The central volcano has a rim that rises to about above sea level, making it the second highest mountain in Iceland, being lower than Hvannadalshnjúkur. The caldera is about , u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tholeiitic Basalt
The tholeiitic magma series () is one of two main magma series in subalkaline igneous rocks, the other being the calc-alkaline series. A magma series is a chemically distinct range of magma compositions that describes the evolution of a mafic magma into a more evolved, silica rich end member. Rock types of the tholeiitic magma series include tholeiitic basalt, ferro-basalt, tholeiitic basaltic andesite, tholeiitic andesite, dacite and rhyolite. The variety of basalt in the series was originally called ''tholeiite'' but the International Union of Geological Sciences recommends that ''tholeiitic basalt'' be used in preference to that term.Le Maitre ''et al.'' 2002 Tholeiitic rock types tend to be more enriched in iron and less enriched in magnesium and aluminium than calc-alkaline rock types. They are thought to form in a less oxidized environment than calc-alkaline rocks. Tholeiitic basalt is formed at mid-ocean ridges and makes up much of the oceanic crust. Almost all the ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mantle (geology)
A mantle is a layer inside a planetary body bounded below by a Planetary core, core and above by a Crust (geology), crust. Mantles are made of Rock (geology), rock or Volatile (astrogeology), ices, and are generally the largest and most massive layer of the planetary body. Mantles are characteristic of planetary bodies that have undergone planetary differentiation, differentiation by density. All Terrestrial planet, terrestrial planets (including Earth), half of the giant planets, specifically ice giants, a number of Asteroid, asteroids, and some planetary Natural satellite, moons have mantles. Examples Earth The Earth's mantle is a layer of Silicate minerals, silicate rock between the Crust (geology), crust and the Earth's outer core, outer core. Its mass of 4.01 × 1024 kg is 67% the mass of the Earth. It has a thickness of making up about 84% of Earth's volume. It is predominantly solid, but in Geologic time scale, geological time it behaves as a Viscosity, visc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenocryst
image:montblanc granite phenocrysts.JPG, 300px, Granites often have large feldspar, feldspathic phenocrysts. This granite, from the Switzerland, Swiss side of the Mont Blanc massif, has large white phenocrysts of plagioclase (that have trapezoid shapes when cut through). 1 euro coin (diameter 2.3 cm) for scale. A phenocryst is an early forming, relatively large and usually conspicuous crystal distinctly larger than the grains of the rock Matrix (geology), groundmass of an igneous rock. Such rocks that have a distinct difference in the size of the crystals are called Porphyry (geology), porphyries, and the adjective porphyritic is used to describe them. Phenocrysts often have euhedral forms, either due to early growth within a magma, or by post-emplacement recrystallization (geology), recrystallization. Normally the term ''phenocryst'' is not used unless the crystals are directly observable, which is sometimes stated as greater than in diameter. Phenocrysts below this level, but s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Feldspar
Feldspar ( ; sometimes spelled felspar) is a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagioclase'' (sodium-calcium) feldspars and the ''alkali'' (potassium-sodium) feldspars. Feldspars make up about 60% of the Earth's crust and 41% of the Earth's continental crust by weight. Feldspars crystallize from magma as both intrusive and extrusive igneous rocks and are also present in many types of metamorphic rock. Rock formed almost entirely of calcic plagioclase feldspar is known as anorthosite. Feldspars are also found in many types of sedimentary rocks. Etymology The name ''feldspar'' derives from the German , a compound of the words ' ("field") and ("flake"). had long been used as the word for "a rock easily cleaved into flakes"; was introduced in the 18th century as a more specific term, referring perhaps to its comm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Porphyritic
Porphyritic is an adjective used in geology to describe igneous rocks with a distinct difference in the size of mineral crystals, with the larger crystals known as phenocrysts. Both extrusive and intrusive rocks can be porphyritic, meaning all types of igneous rocks can display some degree of porphyritic texture. Most porphyritic rocks have bimodal size ranges, meaning the rock is composed of two distinct sizes of crystal. In extrusive rocks, the phenocrysts are surrounded by a fine-grained (aphanitic) matrix or groundmass of volcanic glass or non-visible crystals, commonly seen in porphyritic basalt. Porphyritic intrusive rocks have a matrix with individual crystals easily distinguished with the eye, but one group of crystals appearing clearly much bigger than the rest, as in a porphyritic granite. The term comes from the Ancient Greek (), meaning " purple". Purple was the color of royalty, and the "imperial porphyry" was a deep purple igneous rock with large crystal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plagioclase
Plagioclase ( ) is a series of Silicate minerals#Tectosilicates, tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continuous solid solution series, more properly known as the plagioclase feldspar series. This was first shown by the German mineralogist Johann F. C. Hessel, Johann Friedrich Christian Hessel (1796–1872) in 1826. The series ranges from albite to anorthite endmembers (with respective compositions NaAlSi3O8 to CaAl2Si2O8), where sodium and calcium atoms can substitute for each other in the mineral's crystallography, crystal lattice structure. Plagioclase in hand samples is often identified by its polysynthetic crystal twinning or "phonograph record, record-groove" effect. Plagioclase is a major constituent mineral in Earth's crust and is consequently an important diagnostic tool in petrology for identifying the composition, origin and evolutio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
