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 800 Ma (million years ago, boundary defined chronometrically) to approximately 635 Ma. 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. ... 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. ... Varanger Peninsula is a peninsula in Finnmark, north-eastern Norway, by the Barents Sea. ... Glaciation, 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 term meaning year. ...

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 several 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 is the third-closest planet to the Sun. ... Aletsch glacier, Switzerland A glacier is a large, long-lasting river of ice that is formed on land and moves in response to gravity. ... This article is about glacial sediments, for other uses see till (disambiguation). ... World map showing North America A satellite composite image of North America North America is a continent in the northern hemisphere bordered on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the south by the Caribbean Sea, and on the west by the... Royal motto: Nemo me impune lacessit (English: No one provokes me with impunity) Scotlands location within the UK Languages English, Gaelic, Scots Capital Edinburgh Largest city Glasgow First Minister Jack McConnell Area - Total - % water Ranked 2nd UK 78,782 km² 1. ... 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. ... Varanger Peninsula is a peninsula in Finnmark, north-eastern Norway, by the Barents Sea. ... Tillite is lithified till. ... 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...

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 limestones -- sediments which are normally warm water above and below and intermixed with glacial deposits. Acritarchs are small organic structures found as fossils. ... General Name, Symbol, Number oxygen, O, 8 Chemical series Chalcogens Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... Layers of Atmosphere (NOAA) Earths atmosphere is a layer of gases surrounding the planet Earth and retained by the Earths gravity. ... Limey shale overlaid by limestone. ... Water (from the Old English word wæter; c. ...

Paleomagnetism seems to show very high continental drift rates, leading some geologists to question whether some of the phenomena might be due to magnetic pole wandering (inertial interchange true polar wander: see the work of J. Kirschvink (Caltech news release, link below) rather than plate motion and low latitude glaciation. 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. ... Portrayal of shifting continents The concept of continental drift was first proposed by Alfred Wegener. ... This article does not cite its references or sources. ... California Institute of Technology The California Institute of Technology (commonly known as Caltech) is a private, coeducational university located in Pasadena, California, in the United States. ... Latitude, sometimes denoted by the Greek letter φ, gives the location of a place on Earth north or south of the Equator. ... Centrifugal force stems from Latin centrum center and fugere to flee. In Newtonian physics [1] it is the centripetal force that induces curved motion. ... 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 from 450 Ma to 420 Ma, the Karoo glaciation from 360 Ma to 260 Ma, and the Cenozoic 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 Karoo is a semi-desert region of South Africa. ... The Cenozoic Era (sometimes still Caenozoic in the United Kingdom) is the most recent of the four classic geological eras. ...

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. URL accessed on January 5, 2006.
• James G. Ogg (2004). Status on Divisions of the International Geologic Time Scale. Lethaia 37: 183–199.