Worldwide glaciation episodes during the Proterozoic eon
Artist's rendition of a fully-frozen Snowball Earth with no remaining liquid surface water.
Proterozoic snowball periods
−1000 —
–
−950 —
–
−900 —
–
−850 —
–
−800 —
–
−750 —
–
−700 —
–
−650 —
–
−600 —
–
−550 —
Tonian
Cryogenian
Ediacaran
Sturtian[1]
Marinoan[1]
← Gaskiers
(millions of years ago)
Baykonurian
Neoproterozoic era
Snowball Earth
Estimate of Proterozoic glacial periods.[2][1]
Dating of pre-Gaskiers glaciations is uncertain. As for the Kaigas, its very existence is doubted by some. The Huronian glaciation, is not shown, there is a lack of any significant evidence for a Snowball Earth during the time period.
The Snowball Earth is a geohistorical hypothesis that proposes during one or more of Earth's icehouse climates, the planet's surface became entirely or nearly entirely frozen with no liquid oceanic or surface water exposed to the atmosphere. The most academically referred period of such global glaciation is believed to have occurred sometime before 650 mya during the Cryogenian period.
Proponents of the hypothesis argue that it best explains sedimentary deposits that are generally believed to be of glacial origin at tropical palaeolatitudes and other enigmatic features in the geological record. Opponents of the hypothesis contest the geological evidence for global glaciation and the geophysical feasibility of an ice- or slush-covered ocean,[3][4] and they emphasize the difficulty of escaping an all-frozen condition. Several unanswered questions remain, including whether Earth was a full snowball or a "slushball" with a thin equatorial band of open (or seasonally open) water. The snowball-Earth episodes are proposed to have occurred before the sudden radiation of multicellular bioforms known as the Cambrian explosion. The most recent snowball episode may have triggered the evolution of multicellularity.
^ abcCite error: The named reference Pu was invoked but never defined (see the help page).
^Smith, A. G. (2009). "Neoproterozoic timescales and stratigraphy". Geological Society, London, Special Publications. 326 (1): 27–54. Bibcode:2009GSLSP.326...27S. doi:10.1144/SP326.2. S2CID 129706604.
^Kirschvink, J. L. (1992). "Late Proterozoic low-latitude global glaciation: The snowball Earth" (PDF). In Schopf, J. W.; Klein, C. (eds.). The Proterozoic Biosphere: A Multidisciplinary Study. Cambridge University Press. pp. 51–2.
^Allen, Philip A.; Etienne, James L. (2008). "Sedimentary challenge to Snowball Earth". Nature Geoscience. 1 (12): 817–825. Bibcode:2008NatGe...1..817A. doi:10.1038/ngeo355.
The SnowballEarth is a geohistorical hypothesis that proposes during one or more of Earth's icehouse climates, the planet's surface became entirely or...
Hemisphere. A "snowballEarth" is the complete opposite of greenhouse Earth in which Earth's surface is completely frozen over. However, a snowballEarth technically...
couple of severe ice ages called SnowballEarths. After the last SnowballEarth about 600 Ma, the evolution of life on Earth accelerated. About 580 Ma, the...
oxygenated water. The SnowballEarth hypothesis provided an alternative explanation for these younger deposits. In a SnowballEarth state the continents...
glaciation possibly covered the entire planet, in an event called the SnowballEarth. The end of the glaciation was caused by volcanic release of carbon...
Neoproterozoic, 1000 to 539 Ma, much of Earth might have been covered in ice. This hypothesis has been termed "SnowballEarth", and it is of particular interest...
glaciation began, freezing the entire planet in a state known as a snowballEarth. After 70 million years it ended, but was quickly followed by the global...
the snowballEarth, simple life could have had time to innovate and evolve, which could later lead to the evolution of multicellularity. The snowball Earth...
explains how other microorganisms could have survived when the Earth (according to the SnowballEarth hypothesis) was entirely frozen over. Ice-covered oceans...
Nuclear winter Timeline of volcanism on Earth The Sturtian glaciation is controversially referred to as "SnowballEarth." Each reconstruction results different...
Ediacara biota, which appears soon after the last "SnowballEarth" episode. However, the snowball episodes occurred a long time before the start of the...
of SnowballEarth argue that it was caused in the first place by a reduction in atmospheric CO2. The hypothesis also warns of future SnowballEarths. In...
Cryogenian, when ice sheets may have reached the equator and formed a "SnowballEarth". The earliest fossils of complex multicellular life are found in the...
and Rhyacian periods of the Paleoproterozoic) and the hypothesized SnowballEarth (during the Cryogenian period in the late Neoproterozoic); and the Ediacaran...
temperatures covered much of the Earth in glaciers and ice sheets. This hypothesis has been termed the "SnowballEarth", and it is of particular interest...
extreme cooling of the global climate around 717–635 Ma (the so-called SnowballEarth of the Cryogenian period) and the rapid evolution of primitive life...
is also when a significant glaciation event known as 'SnowballEarth' occurred. SnowballEarth covered almost the entire planet with ice. The areas that...
there were at least four during the Neoproterozoic, climaxing with the SnowballEarth of the Varangian glaciation. The Phanerozoic Eon is the current eon...
composition is the foundation for this theory. In the snowballEarth episode, the surface ocean of Earth is covered by the sea ice that separates the ocean...
following the end of the Cryogenian global glaciation known as the SnowballEarth. The relatively sudden evolutionary radiation event, known as the Avalon...
Rodinia, birth of Gondwana, true polar wander and the snowballEarth". Journal of African Earth Sciences. 28 (1): 17–33. Bibcode:1999JAfES..28...17H....
that formed the protoplanets. This episode mainly focuses on the two SnowballEarth events in the mid-Precambrian period, and the effect they had on life...
of approximately 57 million years. It is hypothesised to have been a SnowballEarth event, or contrastingly multiple regional glaciations, and is the longest...
it has been suggested that it produced a second "SnowballEarth", i.e. a period during which Earth was completely covered in ice. It has also been suggested...
of the first magnetofossils) and the SnowballEarth hypothesis. He is also Principal Investigator (PI) of Earth–Life Science Institute. In 1988, Kirschvink...
years) may also have been a snowballEarth event though this is unproven. The changes that lead to the initiation of snowballEarth events are not well known...
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