Snowball Earth Glaciations
Introduction
-Definitions
The Snowball Earth is a hypothesis fronted by Joseph Kirschvink, suggesting that during the Cryogenian era, the earth was covered in ice in its entirety for a period of 100million years.
-Historical Information
The hypothesis that has been put forward to support this suggest that there was a significant reduction of greenhouse gases such as methane and carbon dioxide followed by a reflection of solar radiation into space by the ice and snow covering the earth’s surface leading to the immense loss of the earth’s heat.
Evidence and Counter-Evidence
-Evidence:
Distinctive signs of ice ages in a substantial number of the Neoproterozoic age deposits despite their involvement with carbonate rocks
The documented magnetic evidence of the ice-age carbonates existence in close proximity to the equator. This claim is further reinforced by the lack of evidence of the earth having been positioned on a different axis as it is in the present day.The appearance of the banded iron formation rocks regardless of their absence for approximately a billion years before. As Kirschvink suggested, the water bodies had been covered in ice reducing the oxygen content translating into the build-up of dissolved iron.
-Counter-Evidence:
Most global deposits are assumed to be diachronous and rarely extend beyond the cumulative Phanerozoic glaciations
Indications of the open water such as wave ripples within the strata of the Marinoan and Sturtian glaciationsLack of massive palynoflora extinctions that would be expected alongside Marinoan and Sturtian glaciations in central Australia regions due to greenhouse effects
Causes and Mechanisms
Low availability of the greenhouse gases such as methane (CH4) and Carbon dioxide (CO2) causing a runaway cooling effect
Earth passing through special space clouds
Conclusion
Brief reiteration of the Snowball Earth hypothesis
Highlights of the evidence and counter-evidence
The causes and mechanisms of this phenomenon
Closing remarks that prompt further insight and discussion of the topic