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Lockne Crater
Lockne is a meteorite crater, located approximately south of the city of Östersund in northern Sweden. It has been suggested that it is a doublet with the nearby smaller Målingen Crater, apart.Raul Rincon (2014BBC News: "Ancient Earth hammered by double space impact", 18 March 2014 accessed 19 March 2014. Computer simulations suggest that the asteroid that created the Lockne crater was some in diameter, and the one that carved out Målingen crater was about across. It is in diameter and the age is estimated, based on accompanying chitinozoan microfossils, to be 458 million years (Late Ordovician). The crater is exposed at the surface. Its fossils, typical of shallow marine environments, show it to be a marine target impact event An impact event is a collision between astronomical objects causing measurable effects. Impact events have been found to regularly occur in planetary systems, though the most frequent involve asteroids, comets or meteoroids and have minimal effe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meteorite
A meteorite is a rock (geology), rock that originated in outer space and has fallen to the surface of a planet or Natural satellite, moon. When the original object enters the atmosphere, various factors such as friction, pressure, and chemical interactions with the atmospheric gases cause it to heat up and radiate energy. It then becomes a meteor and forms a Meteoroid#Fireball, fireball, also known as a shooting star; astronomers call the brightest examples "Bolide#Astronomy, bolides". Once it settles on the larger body's surface, the meteor becomes a meteorite. Meteorites vary greatly in size. For geologists, a bolide is a meteorite large enough to create an impact crater. Meteorites that are recovered after being observed as they transit the atmosphere and impact event, impact Earth are called meteorite falls. All others are known as meteorite finds. Meteorites have traditionally been divided into three broad categories: stony meteorites that are rocks, mainly composed of sil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Impact Crater
An impact crater is a depression (geology), depression in the surface of a solid astronomical body formed by the hypervelocity impact event, impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters typically have raised rims and floors that are lower in elevation than the surrounding terrain. Impact craters are typically circular, though they can be elliptical in shape or even irregular due to events such as landslides. Impact craters range in size from microscopic craters seen on lunar rocks returned by the Apollo Program to simple bowl-shaped depressions and vast, complex, multi-ringed impact basins. Meteor Crater is a well-known example of a small impact crater on Earth. Impact craters are the dominant geographic features on many solid Solar System objects including the Moon, Mercury (planet), Mercury, Callisto (moon), Callisto, Ganymede (moon), Ganymede, and most small moons and asteroids. On other planet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Östersund
Östersund (; ) is an Urban areas in Sweden, urban area (Stad (Sweden), city) in Jämtland in northern Sweden. It is the seat of Östersund Municipality and the capital of Jämtland County. Östersund is located at the shores of Sweden's fifth-largest lake, Storsjön, opposite the island Frösön. It is the only city in Jämtland. The northern part of the urban area is located inside of the municipality of Krokom Municipality, Krokom. Östersund is the region's cultural and economical centre and by tradition a city of trade and commerce. The city had one of the most extensive garrisons in Sweden prior to its closure in the early-21st century. Östersund is home to Mid Sweden University's largest campus site with approximately 7,000 students. With a total population of 50,960 (2017) Östersund is the List of cities in Sweden by population, 22nd most populous city in Sweden, the List of cities in Scandinavia by population, 46th most populous city in Scandinavia, and by far the largest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MÃ¥lingen Crater
Målingen was confirmed as an impact crater in 2014. It is located near the city of Östersund in northern Sweden. It is "probable" that it formed simultaneously with the nearby Lockne crater.Raul Rincon (2014)BBC News: "Ancient Earth hammered by double space impact", 18 March 2014 accessed 19 March 2014. Computer simulations suggest the asteroid pieces that created the Lockne and Målingen craters were some 600 meters and 250 meters in diameter, respectively. Målingen is in diameter and its age is estimated, using chitinozoan microfossils, which were also found in Lockne, to be 458 million years (Late Ordovician The Late Ordovician is the third and final epoch of the Ordovician period, lasting million years and spanning from around 458.2 to 443.1 million years ago. The rocks associated with this epoch are referred to as the Upper Ordovician Series. At ...). References Impact craters of Sweden Ordovician impact craters Ordovician Sweden Sandbian Landforms of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asteroid
An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). Asteroids are rocky, metallic, or icy bodies with no atmosphere, and are broadly classified into C-type asteroid, C-type (carbonaceous), M-type asteroid, M-type (metallic), or S-type asteroid, S-type (silicaceous). The size and shape of asteroids vary significantly, ranging from small rubble piles under a kilometer across to Ceres (dwarf planet), Ceres, a dwarf planet almost 1000 km in diameter. A body is classified as a comet, not an asteroid, if it shows a coma (tail) when warmed by solar radiation, although recent observations suggest a continuum between these types of bodies. Of the roughly one million known asteroids, the greatest number are located between the orbits of Mars and Jupiter, approximately 2 to 4 astronomical unit, AU ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chitinozoan
Chitinozoa (singular: chitinozoan, plural: chitinozoans) are a group of flask-shaped, organic walled marine microfossils produced by an as yet unknown organism. Common from the Ordovician to Devonian periods (i.e. the mid-Paleozoic), the millimetre-scale organisms are abundant in almost all types of marine sediment across the globe. This wide distribution, and their rapid pace of evolution, makes them valuable biostratigraphic markers. Their bizarre form has made classification and ecological reconstruction difficult. Since their discovery in 1931, suggestions of protist, plant, and fungal affinities have all been entertained. The organisms have been better understood as improvements in microscopy facilitated the study of their fine structure, and it has been suggested that they represent either the eggs or juvenile stage of a marine animal. However, recent research has alternatively suggested that they represent the test of a group of protists with uncertain affinities. Chitin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microfossil
A microfossil is a fossil that is generally between 0.001 mm and 1 mm in size, the visual study of which requires the use of light or electron microscopy. A fossil which can be studied with the naked eye or low-powered magnification, such as a hand lens, is referred to as a macrofossil. Microfossils are a common feature of the geological record, from the Precambrian to the Holocene. They are most common in deposits of marine environments, but also occur in brackish water, fresh water and terrestrial sedimentary deposits. While every kingdom of life is represented in the microfossil record, the most abundant forms are protist skeletons or microbial cysts from the Chrysophyta, Pyrrhophyta, Sarcodina, acritarchs and chitinozoans, together with pollen and spores from the vascular plants. Overview A microfossil is a descriptive term applied to fossilized plants and animals whose size is just at or below the level at which the fossil can be analyzed by the naked e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ordovician
The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era, and the second of twelve periods of the Phanerozoic Eon (geology), Eon. The Ordovician spans 41.6 million years from the end of the Cambrian Period Megaannum, Ma (million years ago) to the start of the Silurian Period Ma. The Ordovician, named after the Celtic Britons, Welsh tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same Rock (geology), rock beds in North Wales in the Cambrian and Silurian systems, respectively. Lapworth recognized that the fossil fauna in the disputed Stratum, strata were different from those of either the Cambrian or the Silurian systems, and placed them in a system of their own. The Ordovician received international approval in 1960 (forty years after Lapworth's death), when it was adopted as an official per ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Impact Event
An impact event is a collision between astronomical objects causing measurable effects. Impact events have been found to regularly occur in planetary systems, though the most frequent involve asteroids, comets or meteoroids and have minimal effect. When large objects impact terrestrial planets such as the Earth, there can be significant physical and Biosphere, biospheric consequences, as the impacting body is usually traveling at several kilometres per second (km/s), with a minimum impact speed of 11.2 km/s (7.0 mi/s) for bodies striking Earth. Atmosphere, While planetary atmospheres can mitigate some of these impacts through the effects of atmospheric entry, many large bodies retain sufficient energy to reach the surface and cause substantial damage. This results in the formation of Impact crater, impact craters and Impact structure, structures, shaping the dominant landforms found across various types of solid objects found in the Solar System. Their prevalence and ubiquity pres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Impact Craters Of Sweden
In early 2018 there were eight known impact structures in Sweden. They range in age from 90 mya to 470 mya, and in diameter from 1 km to 52 km. Six of them are exposed, that is they are visible at the surface, in the natural landscape, although their nature and origin might need to be pointed out to the untrained layman. List * Dellen * Granby crater * Hummeln structure * Lockne crater * Målingen Crater * Mien (lake) * Siljan Ring * Tvären See also * Ordovician meteor event The Ordovician meteor event was a dramatic increase in the rate at which L chondrite meteorites fell to Earth during the Middle Ordovician period, about 467.5±0.28 million years ago, lasting for about 40 million years. This rate increase is ind ...H. Haack et al. ''Meteorite, asteroidal, and theoretical constraints on the 500-Ma disruption of the L chondrite parent body'', Icarus, Vol. 119, p. 182 (1996). References {{Commons category, Impact craters of Sweden Geology of Sweden L ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ordovician Impact Craters
The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era, and the second of twelve periods of the Phanerozoic Eon. The Ordovician spans 41.6 million years from the end of the Cambrian Period Ma (million years ago) to the start of the Silurian Period Ma. The Ordovician, named after the Welsh tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same rock beds in North Wales in the Cambrian and Silurian systems, respectively. Lapworth recognized that the fossil fauna in the disputed strata were different from those of either the Cambrian or the Silurian systems, and placed them in a system of their own. The Ordovician received international approval in 1960 (forty years after Lapworth's death), when it was adopted as an official period of the Paleozoic Era by the International Geological Congress. Life continued to flourish du ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
