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Encyclopedia > Glaciation

A glaciation (a created composite term meaning Glacial Period, referring to the Period or Era of, as well as the process of High Glacial Activity), often called an ice age, is a geological phenomenon in which massive ice sheets form in the Arctic and Antarctic and advance toward the equator. Conversely, the term interglacial or Interglacial Period, such as the current era, is used to denote the absence of large-scale glaciation on a global scale — i.e., a non-Ice Age. Interglacials are, in general, shorter than glacial epochs. Variations in CO2, temperature and dust from the Vostok ice core over the last 400 000 years For the animated movie, see Ice Age (movie). ... Geology (from Greek γη- (ge-, the earth) and λογος (logos, word, reason)) is the science and study of the Earth, its composition, structure, physical properties, history and the processes that shape it. ... Frozen Waterfall in the Rhön mountains A natural, 4 tonne, block of ice on a beach in Iceland Ice can refer to any of the 14 known solid phases of water. ... The red line indicates the 10°C isotherm in July, commonly used to define the Arctic region border The Arctic is the area around the Earths North Pole. ... Antarctica is the continent at the extreme southern latitudes of the Earth, containing the South Pole. ... The equator is an imaginary circle drawn around a planet (or other astronomical object) at a distance halfway between the poles. ...

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What glaciation means

Glaciations are characterized by cool, wet climates and thick ice sheets extending from each pole. Mountain or alpine glaciers in otherwise unglaciated areas expand and extend to lower elevations even in the lowest of latitudes. Sea levels drop due to the presence of large volumes of water above sea level in the icecaps. There is evidence that ocean circulation patterns are disrupted by glaciations. Since the earth has significant continental glaciation in the Arctic and Antarctic, we currently are in a glacial minimum of a glaciation. Such a period between glacial maxima is known as an "interglacial". The current one is the Flandrian. Mount McKinley (Denali) in Alaska (USA) has the largest visible base-to-summit elevation difference on Earth. ... Aletsch glacier, Switzerland A glacier is a large, long-lasting river of ice that is formed on land and moves in response to gravity. ... Latitude, usually denoted symbolically by the Greek letter φ, gives the location of a place on Earth north or south of the Equator. ... The Flandrian interglacial or stage is the name given by geologists and archaeologists in the British Isles to the first, and so far only, stage of the Holocene, covering the period from around 10,000 years ago when the last ice age ended to the present day. ...


In general, the Earth seems to have been ice-free even in high latitudes except during relatively rare glacial maximums such as the one from which we emerged 10 to 15 thousand years ago. Earth is the current Good Article Collaboration of the week! Please help to improve this article to the highest of standards. ...


The causes of glaciations have been much debated ever since the phenomenon was clearly identified in the 17th century. Modern theories tend to revolve around periodic oscillations in the Earth's orbit, hypothesized periodic changes in solar output, and/or the effects of continental masses drifting into polar regions where Antarctica currently resides. (16th century - 17th century - 18th century - more centuries) As a means of recording the passage of time, the 17th century was that century which lasted from 1601-1700. ... Two bodies with a slight difference in mass orbiting around a common barycenter. ...


Named glacial periods

Known periods of glaciation include the Huronian (2400 Ma - 2100 Ma), Sturtian-Varangian (950 Ma - 570 Ma), Andean-Saharan (450 Ma - 420 Ma), Karoo (360 Ma - 260 Ma), Cenozoic (30 Ma - Present). These can be further divided by location and time (e.g.: the names Riss (180,000 - 130,000 years bp) and Würm (70,000 - 10,000 years bp) refer specifically to glaciation at the headwaters of the Donau/Rhine rivers.) Not every year in each interval was a time of complete or even partial glaciation. The best-studied glaciation, that of the recent past, appears to have taken place in at least four separate ice incursions and retreats. Unfortunately, the scouring action of each glaciation tends to remove most of the evidence of prior ice sheets almost completely, except in regions where the later sheet doesn't achieve full coverage. It is probable that glacial periods other than those above have been overlooked because of the paucity of exposed rocks from high latitudes from older periods. The Varanger glaciation was especially severe and may have extended to the Equator. This has led to a recent "Snowball Earth" hypothesis - that the Earth froze over completely in the late Proterozoic, then thawed very rapidly as trapped water and carbon dioxide were returned to Earth's atmosphere. An alternative hypothesis, sometimes called Slushball Earth, maintains that the Equator at least was ice-free. The Huronian glaciation was from 2400 mya to 2100 mya, during the Siderian and Rhyacian periods of the Paleoproterozoic era. ... // Generalità Il Periodo Cryogeniano (dal Greco cryos ghiaccio e genesi, nascita) è il secondo periodo geologico dell Era Neoprotozoica seguito poi dal periodo Ediacarano. ... The Andean-Saharan glaciation was from 450 mya to 420 mya, during most of the Silurian period and the beginning of the Devonian period. ... The Karoo is a semi-desert region of South Africa. ... The Cenozoic Era (sen-oh-ZOH-ik; sometimes Caenozoic Era in the United Kingdom) meaning new life (Greek kainos = new + zoe = life) is the most recent of the three classic geological eras. ... // Generalità Il Periodo Cryogeniano (dal Greco cryos ghiaccio e genesi, nascita) è il secondo periodo geologico dell Era Neoprotozoica seguito poi dal periodo Ediacarano. ... The equator is an imaginary circle drawn around a planet (or other astronomical object) at a distance halfway between the poles. ... The Snowball Earth hypothesis attempts to explain a number of phenomena noted in the geological record by proposing that an ice age that took place in the Neoproterozoic was so severe that the Earths oceans froze over completely, with only heat from the Earths planetary core causing some... In geology, the Proterozoic is an eon prior to the first abundant complex life on earth. ... Water (from the Old English waeter; c. ... Carbon dioxide is an atmospheric gas comprised of one carbon and two oxygen atoms. ... Layers of Atmosphere (NOAA) Air redirects here. ...


Newer means of detecting glaciations

The problem of the removal of evidence of earlier glacials by the later ones has been overcome to some extent by drilling cores of ice and of benthic mud. The ice of an ice cap contains bubbles of the atmosphere of the time when it was trapped. In so far as a high proportion of carbon dioxide represents an interglacial, it is possible to analyze the gas in the bubbles and see when the warmer periods were. Carbon dioxide is an atmospheric gas comprised of one carbon and two oxygen atoms. ...


On the other hand, ice is solid water. A water molecule includes an oxygen atom but some isotopes of oxygen are more readily incorporated into ice crystals than others. Thus, when these are locked up in ice caps, they are rarer in the remaining waters of the world. This is detectable in the layers of mud laid down each year in the ocean depths. Therefore, oxygen isotope variation in the mud varies with time and with the extent of the process of glaciation. As far as they go, the three sources of information, the traditional, the carbon dioxide proportion and the oxygen isotope tend to corroborate each other though the newer ones appear to show more detailed fluctuation in glaciation. General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... Fluctuation Fluctuation refer to an economical term called conjuncture. ...


The term, 'ice age' is used in two ways

The term ice age is used to refer either to a single glaciation or to an entire period of repeated glaciations such as the recent 30 million years of the Cenozoic period, especially the Pleistocene glaciations. Variations in CO2, temperature and dust from the Vostok ice core over the last 400 000 years For the animated movie, see Ice Age (movie). ... The Cenozoic Era (sen-oh-ZOH-ik; sometimes Caenozoic Era in the United Kingdom) meaning new life (Greek kainos = new + zoe = life) is the most recent of the three classic geological eras. ...


See also

  • Timeline of glaciation This includes a graph drawn from carbon dioxide concentrations in ice cores. Its oxygen isotope graph has a much longer time scale.

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