|
Lake Lappajärvi
Lappajärvi is a lake in Finland, in the municipalities of Finland, municipalities of Lappajärvi, Alajärvi and Vimpeli. It is formed in a wide, partly eroded meteorite impact crater. The lake is part of Ähtävänjoki () basin together with Lake Evijärvi that is located downstream (north) of it. The Lappajärvi impact structure is estimated to be 77.85 ± 0.78 million years old (Campanian age of the Late Cretaceous time period). Experts working on Finland's Onkalo spent nuclear fuel repository project have studied Lake Lappajärvi to help them project how Finnish landscapes might look one million years in the future and beyond. An island in the middle of the lake, Kärnänsaari (Kärnä Island), gives the name to the black impact melt rock (impactite) found there, locally called ''Kärnäiitti''. Nearby towns include Lappajärvi and Vimpeli and the nearest major city is Seinäjoki. In September 2023, UNESCO accepted the Lappajärvi area's "Impact Crater Lake" Geopark applica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lappajärvi
Lappajärvi is a municipalities of Finland, municipality in Finland's Southern Ostrobothnia region. It is located from Seinäjoki, from Kokkola and from Vaasa. The municipality has a population of () and covers an area of of which , or nearly 20% is water. The population density is . The municipality is unilingually Finnish language, Finnish. Lake Lappajärvi, which gives the name to the municipality, is a impact crater, meteor crater, one of the few meteor crater lakes found in Finland. Singer and performer, Timo Kotipelto from the worldwide known Finnish power metal band Stratovarius was born and raised in Lappajärvi. Notable people born in Lappajärvi *Johannes Bäck (1872–1952) *Aleksi Hakala (1886–1959) *Veikko Savela (1919–2015) *Jarmo Övermark (1955–) *Arto Melleri (1956–2005) *Seppo Särkiniemi (1957–) *Jussi Lampi (1961–) *Timo Kotipelto (1969–) *Petra Olli (1994–) See also * Lappajärvi Church References External links Municipality of La ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the Latin word for the white limestone known as chalk. The chalk of northern France and the white cliffs of south-eastern England date from the Cretaceous Period. Climate During the Late Cretaceous, the climate was warmer than present, although throughout the period a cooling trend is evident. The tropics became restricted to equatorial regions and northern latitudes experienced markedly more seasonal climatic conditions. Geography Due to plate tectonics, the Americas were gradually moving westward, causing the Atlantic Ocean to expand. The Western Interior Seaway divided North America into eastern and western halves; Appalachia and Laramidia. India maintained a northward course towards Asia. In the Southern Hemisphere, Aus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Argon–argon Dating
Argon–argon (or 40Ar/39Ar) dating is a radiometric dating method invented to supersede Potassium-argon dating, potassiumargon (K/Ar) dating in accuracy. The older method required splitting samples into two for separate potassium and argon measurements, while the newer method requires only one rock fragment or mineral grain and uses a single measurement of isotopes of argon, argon isotopes. 40Ar/39Ar dating relies on neutron irradiation from a nuclear reactor to convert a stable form of potassium (39K) into the radioactive 39Ar. As long as a standard of known age is co-irradiated with unknown samples, it is possible to use a single measurement of argon isotopes to calculate the 40K/40Ar* ratio, and thus to calculate the age of the unknown sample. 40Ar* refers to the radiogenic 40Ar, i.e. the 40Ar produced from radioactive decay of 40K. 40Ar* does not include atmospheric argon adsorbed to the surface or inherited through diffusion and its calculated value is derived from measuring t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gravity Anomaly
The gravity anomaly at a location on the Earth's surface is the difference between the observed value of gravity and the value predicted by a theoretical model. If the Earth were an ideal oblate spheroid of uniform density, then the gravity measured at every point on its surface would be given precisely by a simple algebraic expression. However, the Earth has a rugged surface and non-uniform composition, which distorts its gravitational field. The theoretical value of gravity can be corrected for altitude and the effects of nearby terrain, but it usually still differs slightly from the measured value. This gravity anomaly can reveal the presence of subsurface structures of unusual density. For example, a mass of dense ore below the surface will give a positive anomaly due to the increased gravitational attraction of the ore. Different theoretical models will predict different values of gravity, and so a gravity anomaly is always specified with reference to a particular model. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nature (journal)
''Nature'' is a British weekly scientific journal founded and based in London, England. As a multidisciplinary publication, ''Nature'' features Peer review, peer-reviewed research from a variety of academic disciplines, mainly in science and technology. It has core editorial offices across the United States, continental Europe, and Asia under the international scientific publishing company Springer Nature. ''Nature'' was one of the world's most cited scientific journals by the Science Edition of the 2022 ''Journal Citation Reports'' (with an ascribed impact factor of 50.5), making it one of the world's most-read and most prestigious academic journals. , it claimed an online readership of about three million unique readers per month. Founded in the autumn of 1869, ''Nature'' was first circulated by Norman Lockyer and Alexander MacMillan (publisher), Alexander MacMillan as a public forum for scientific innovations. The mid-20th century facilitated an editorial expansion for the j ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Crater Lake
A volcanic crater lake is a lake in a volcanic crater, crater that was formed by explosive eruption, explosive activity or a caldera, collapse during a types of volcanic eruptions, volcanic eruption. Formation Lakes in calderas fill large craters formed by the collapse of a volcano during an eruption. Lakes in maars fill medium-sized craters where an eruption deposited debris around a vent. Crater lakes form as the created depression, within the Rim (craters), crater rim, is filled by water. The water may come from Precipitation (meteorology), precipitation, groundwater circulation (often Hot Spring, hydrothermal fluids in the case of volcanic craters) or melted ice. Its level rises until an equilibrium is reached between the rates of incoming and outgoing water. Sources of water loss singly or together may include evaporation, subsurface seepage, and, in places, surface leakage or overflow when the lake level reaches the lowest point on its rim. At such a saddle location, the u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentti Eskola
Pentti Elias Eskola (8 January 1883 – 6 December 1964) was a Finland, Finnish geologist who specialised in the petrology of granites and developed the concept of metamorphic facies. He won the Wollaston Medal in 1958, the Vetlesen Prize in 1964, and was given a state funeral upon his death. The mineral eskolaite is named in his honor. Eskola was born in Lellainen, the son of a farmer. He graduated from the University of Helsinki in 1906 and received a doctorate in 1914 with a dissertation on the petrology of the Orijärvi Region. Eskola was a student of Wilhelm Ramsay. He visited Norway and the US in 1920–21 working at the Geophysical Laboratory in Washington, D.C., and with the Geological Survey of Canada during which time he examined eclogites. He became a geologist for the Finnish Survey in 1922 and joined as a professor of geology at Helsinki in 1924 working there until 1954. Eskola's major work on metamorphism was influenced by the work of Jakob Sederholm, J.J. Sederho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Yanisyarvi
Lake Yanisyarvi (; ) is a lake in the Republic of Karelia, Russia, located north of and draining to Lake Ladoga. The basin of this somewhat circular lake was formed by meteorite impact 700±5 million years ago during the Cryogenian period. The crater is in diameter. Prior to World War II, the lake was thought to be the second known volcanic caldera in Finland (the other was Lake Lappajärvi). Both were eventually recognized as impact craters. References External linksLake Jänisjärvi Impact Craterat NASA Earth Observatory NASA Earth Observatory is an online publishing outlet for NASA which was created in 1999. It is the principal source of satellite imagery and other scientific information about the climate and the environment which are being provided by NASA for ... Impact craters of Russia LYanisyarvi Impact craters of the Arctic Impact crater lakes {{Earth-crater-stub Lakes of the Sortavalsky District ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Rock
Volcanic rocks (often shortened to volcanics in scientific contexts) are rocks formed from lava erupted from a volcano. Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and metamorphic rocks and constitute an important element of some sediments and sedimentary rocks. For these reasons, in geology, volcanics and shallow hypabyssal rocks are not always treated as distinct. In the context of Precambrian shield geology, the term "volcanic" is often applied to what are strictly metavolcanic rocks. Volcanic rocks and sediment that form from magma erupted into the air are called "pyroclastics," and these are also technically sedimentary rocks. Volcanic rocks are among the most common rock types on Earth's surface, particularly in the oceans. On land, they are very common at plate boundaries and in flood basalt provinces. It has been estimated that volcanic rocks cover about 8% of the Earth's current land surface. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dacite
Dacite () is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite. It is composed predominantly of plagioclase feldspar and quartz. Dacite is relatively common, occurring in many tectonic settings. It is associated with andesite and rhyolite as part of the subalkaline tholeiitic and calc-alkaline magma series. Etymology The word ''dacite'' comes from Dacia, a province of the Roman Empire which lay between the Danube River and Carpathian Mountains (now modern Romania and Moldova) where the rock was first described. The term ''dacite'' was used for the first time in the scientific literature in the book ''Geologie Siebenbürgens'' (''The Geology of Transylvania'') by Austrian geologists Franz Ritter von Hauer and Guido Stache. Dacite was originally defined as a new rock type to separate calc-alkaline ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coesite
Coesite () is a form (polymorphism (materials science), polymorph) of silicon dioxide (silicon, Sioxide, O2) that is formed when very high pressure (2–3 gigapascals), and moderately high temperature (), are applied to quartz. Coesite was first synthesized by Loring Coes, Jr., a chemist at the Norton Company, in 1953. The word ''coesite'' is pronounced as "Coze-ite", after chemist Loring Coes, Jr. Occurrences In 1960, a natural occurrence of coesite was reported by Edward C. T. Chao, in collaboration with Eugene Shoemaker, from Barringer Crater, in Arizona, US, which was evidence that the crater must have been formed by an impact. After this report, the presence of coesite in unmetamorphosed rocks was taken as evidence of a meteorite impact event or of an atomic bomb explosion. It was not expected that coesite would survive in high pressure metamorphic rocks. In metamorphic rocks, coesite was initially described in eclogite xenoliths from the mantle (geology), mantle of the Ear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Suevite
Suevite is a rock consisting partly of melted material, typically forming a breccia containing glass and crystal or lithic fragments, formed during an impact event. It forms part of a group of rock types and structures that are known as impactites. Name The word "suevite" is derived from "Suevia", Latin name of Swabia. The geologist Oliver Sachs was able to show that, over the course of the 19th and 20th centuries, this type of rock was recognized as something special and, in 1919, was formally introduced into petrographic science by Adolf Sauer under the name "suevite".J. O. Sachs: ''Wie der Schwabenstein zu seinem Namen kam.'' In: W. Rosendahl, M. Schieber (Hrsg.): ''Der Stein der Schwaben. Natur- und Kulturgeschichte des Suevits.'' Band 4, Staatsanzeiger-Verlag, Stuttgart 2009. Formation Suevite is thought to form in and around impact craters by the sintering of molten fragments together with unmelted clasts of the country rock. Rocks formed from more completely melted mat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
