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Encyclopedia > Cryogenian

The Cryogenian Period (from Greek cryos "ice" and genesis "birth") is the second geologic period of the Neoproterozoic Era, followed by the Ediacaran Period. The Cryogenian includes the Sturtian and Marinoan (formerly considered together as the Varanger) glaciations, and lasted from 850 Ma (as defined by the ICS based on radiometric chronometry) to approximately 635 Ma. World geologic provinces Oceanic crust  0-20 Ma  20-65 Ma  >65 Ma Geologic provinces  Shield  Platform  Orogen  Basin  Large igneous province  Extended crust Geology (from Greek γη- (ge-, the earth) and λογος (logos, word, reason))[1] is the science and study of the solid matter of a celestial body, its composition... In geology, a period or age is a time span of many millions of years that are assumed to have had similar characteristics. ... The Neoproterozoic is the geological era from 1000 Ma to 542 Ma (million years ago). ... A geologic era is a subdivision of geologic time that is a separate classification that divides the Phanerozoic Eon into three parts timeframes. ... The Ediacaran Period is the last geological period of the Neoproterozoic Era, just before the Cambrian. ... The Sturtian-Varangian is a late Precambrian world-wide glaciation episode ranging from 950Ma to 600Ma, represented by tillite deposits in Congo, Australia, China, North America, Sahara and Norway. ... The Cryogenian Period (from Greek cryos ice and genesis birth) is the second geologic period of the Neoproterozoic Era, followed by the Ediacaran Period. ... 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. ... Annum is a Latin noun meaning year. ... The International Commission on Stratigraphy concerns itself with stratigraphy on a global scale. ... Radiometric dating is a technique used to date materials based on a knowledge of the decay rates of naturally occurring isotopes, and the current abundances. ...


The name is derived from the glacial deposits characteristic of the period, indicating that at this time, the Earth suffered the most severe ice ages in its history, with glaciers extending to the equator, in a series of rhythmical pulses. These glaciations are represented by tillite deposits in Congo, Sahara, and Oman, in Australia and in China, and in North America, Ireland, Scotland, and Norway, and many other places around the world. It is generally considered to be divisible into at least two (Sturtian around 750 to 700 Ma and Marinoan/Varanger which terminated at ca. 635 Ma) major worldwide glaciations. The tillite deposits occur also in places which were at low latitudes during the Cryogenian, a phenomenon which led to the hypothesis of the deeply-frozen planetary oceans called "Snowball Earth". Earth (IPA: , often referred to as the Earth, Terra, the World or Planet Earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth largest. ... A glacier is a large, long-lasting river of ice that is formed on land and moves in response to gravity and undergoes internal deformation. ... Glacial till with tufts of grass Till is an unsorted glacial sediment. ... World map showing North America A satellite composite image of North America. ... Motto: (Latin for No one provokes me with impunity)1 Anthem: Multiple unofficial anthems Capital Edinburgh Largest city Glasgow Official language(s) English, Gaelic, Scots 2 Government Constitutional monarchy  - Queen Queen Elizabeth II  - Prime Minister of the UK Tony Blair MP  - First Minister Jack McConnell MSP Unification    - by Kenneth I... The Snowball Earth hypothesis is a controversial hypothesis (Sankaran, 2003) that 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 population of acritarchs crashed during this glaciation and it is claimed that oxygen levels in the atmosphere increased after the glaciation. There are a number of enigmatic features about this glaciation, including indications of glaciation at very low latitudes and the presence of capstones of limestone -- which are normally warm water sediments -- above and below and intermixed with glacial deposits. The reappearance of banded iron formations associated with the glacial periods suggests low and fluctuating oxygen levels, not seen since the Paleoproterozoic period, also temporarily returned. Acritarchs are small organic structures found as fossils. ... General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Atomic mass 15. ... Layers of Atmosphere (NOAA) Air redirects here. ... The capstone is the highest rock or mount of a structure. ... Limey shale overlaid by limestone. ... Water is an odourless substance that is essential to all known forms of life and is known as the universal solvent. ... 2. ... General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Atomic mass 15. ...


Paleomagnetism studies appear to show very high continental drift rates, leading some geologists to question whether some of the phenomena might be due to magnetic pole wandering, rather than plate motion and low latitude glaciation.[citation needed] Basically, a very lopsided distribution of continental crust causes the Earth's daily rotation to cause centrifugal force which would cause the Earth to rotate (while its daily rotation axis stays in the same direction) until the aggregation of continents is on the equator; this causes apparent continental drift that is much faster than average rates. Paleomagnetism refers to the orientation of the Earths magnetic field as it is preserved in various magnetic iron bearing minerals throughout time. ... Continental drift, first proposed as a theory by Alfred Wegener in 1912, is the movement of the Earths continents relative to each other. ... The magnetosphere shields the surface of the Earth from the charged particles of the solar wind. ... Latitude, usually denoted symbolically by the Greek letter φ, gives the location of a place on Earth north or south of the Equator. ... Centrifugal force (from Latin centrum center and fugere to flee) is a term which may refer to two different forces which are related to rotation. ... World map showing the equator in red The Equator is an imaginary circle drawn around a planet (or other astronomical object) at a distance halfway between the poles. ...


Other known world-wide glaciations include the Huronian from 2400 Ma to 2100 Ma, Andean-Saharan or Ordovician glaciation from 450 Ma to 420 Ma, the Karoo or Carboniferous-Permian glaciation from 360 Ma to 260 Ma, and the Cenozoic Quarternary glaciation which started 30 Ma in Antarctica and is ongoing. The Huronian glaciation was from 2400 mya to 2100 mya, during the Siderian and Rhyacian periods of the Paleoproterozoic era. ... 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 Ordovician period is the second of the six (seven in North America) periods of the Paleozoic era. ... The Karoo Ice Age from 350-250 million years ago was the second major period of Glaciation of the Phanerozoic Era. ... The Carboniferous is a major division of the geologic timescale that extends from the end of the Devonian period, about 359. ... The Permian is a geologic period that extends from about 299. ... 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. ... The Quaternary Period is the geologic time period from the end of the Pliocene Epoch roughly 1. ...


External links

  • Scientists discover that "evolutionary big bang" may have been caused by Earth losing its balance half a billion years ago — Caltech news release

References

  • Cryogenian Period. GeoWhen Database. Retrieved on January 5, 2006.
  • James G. Ogg (2004). "Status on Divisions of the International Geologic Time Scale". Lethaia 37: 183–199.
Proterozoic eon
Paleoproterozoic era Mesoproterozoic era Neoproterozoic era
Siderian Rhyacian Orosirian Statherian Calymmian Ectasian Stenian Tonian Cryogenian Ediacaran

  Results from FactBites:
 
Cryogenian - Wikipedia, the free encyclopedia (489 words)
The Cryogenian Period (from Greek cryos "ice" and genesis "birth") is the second geologic period of the Neoproterozoic Era, followed by the Ediacaran Period.
The Cryogenian includes the Sturtian and Marinoan (formerly considered together as the Varanger) glaciations, and lasted from 850 Ma (as defined by the ICS based on radiometric chronometry) to approximately 635 Ma.
The population of acritarchs crashed during this glaciation and it is claimed that oxygen levels in the atmosphere increased after the glaciation.
SNOWBALL EARTH (1473 words)
Characteristic structures in younger Cryogenian cap carbonates (right): giant wave ripples in the Keilberg cap dolostone, NW Namibia, sea-floor cements (former aragonite crystal fans) in the Hayhook cap limestone, NW Canada.
O) isotopic profiles of the younger Cryogenian cap-carbonate sequence and the pre-glacial Trezona anomaly, Otavi Group carbonate platform near Ombaatjie, NW Namibia.
This contrasts with tightly clustered isotopic data from 635-Ma cap dolostones in Namibia, Svalbard and NW Canada, which are interpreted to reflect equilibrium with contemporaneous seawater.
  More results at FactBites »

 
 

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