State of Research on the "Snowball Earth Hypothesis"
The "Snowball Earth Hypothesis" also known as the "Varangia glaciation" is a hypothesis presented in 2001 by Geologist Paul Hoffman. (Wikipedia, 2002)
The hypothesis purposes that 540 million years ago during the Neoproterozic, a meter thick of ice covered the oceans and glaciers the continents for 100 million years. Albedo; when ice and snow reflect solar radiation into space, in absents of greenhouse gases, which don't exist within the atmosphere, heat therefore escapes the planet. A condition of temperature disequilibrium occurs, when freezing cold reaches a state, the climate never warms to normal, and cold freezes the hemisphere and buries it under massive glaciation.
The glaciers begin when a green house gas, carbon dioxide, is depleted from erosion of silicates. Once the atmosphere is depleted of carbon dioxide, it can not absorb solar radiation. The global tempertures drops to cold and glaciation occurs, glaciation continues, temperature gradients drop further to colder, below freezing, cold is irreversible, glaciers reflect solar radiation into space. The lack of atmospheric carbon dioxide prevented greenhouse from occurring, earth is frozen until the hemisphere is totally glaciated. (Hoffman, 1998)
Deglaciation can occur when volcanic eruptions saturate the atmosphere with carbon dioxide gas and resume the greenhouse effect on climate. Solar radiation is absorbed by greenhouse gases, rewarming the climate. A dramatic expansion of the biosphere occurred. ("Cold")
History of "Snowball Earth Hypothesis"
A tree toppled during a hurricane. A 700 million year old rock bed was discovered in Appalachia. The rock, diamictite consisted of basalt -size cobbles mixed with a slurry of fine silt and sand. The region consisting of Appalachian Blue Ridge range, Sharp Top mountain had once bordered a seaway cutting through Rhodina, a giant continent that included most of the worlds land. Sharp Top contained signs of tides, indicating the glacier had streached down to the sea. During this time, Virginia was 15' to 30' of the equator. Scientist wanted to know why ice was on the equator during the Neoproterozoic era. (Monastersky,1998)
The team of scientists consisted of a biogeologist, geochemist, and tectonic geologist with the common goal of understanding the coevolution of life and environments in Earth History. The research centered on three critical intervals of planetary change and major transitions in the co-evolution of life on earth. (Knoll)
In 1998 the team of geologists had culled clues from Namibia and fashioned the Snowball hypothesis. (monastersky, 1998)
Source and Nature of research
The research into collecting data proving or disproving Snowball Earth was conducted by geologists who had collected Neoproterozoic rock samples in Australia, China, western U.S., Arctic Islands of Svalbard and the Namibia coast. (Hoffman, et al. 1998)