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State Of Research On "Snowball Earth Hypothesis"

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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)

Research included conducting a geologic survey of the Congo craton, facies of Ghaub formation fill valleys. Rock specimens were taken from the lower glacial intervals (Chugs Formation) to just beneath the unconformity at the base of Mulden group, Southern Damara margin of the craton and Kaoko craton, Kalahari craton, Amadeus basin. These rock specimens were microdrilled and the elements Sr, Mn, Fe, Ca, Mg were measured for abundance using inductively coupled plasma emission spectoscopy to assess diagenetic alteration. These sample were analyzed offline for DELTA 13 CARBON AND DELTA 18 OXYGEN after digestion for 3 hours in H2po4 at 50'C to insure complete reaction of dolomite: the evolved gas was measured on a finnigan mat, other research consisted of fisions secter mass spectrometer, graphite -furnace atomic absorption spectoscopy, leached in NH4CH3COO, digestion in weak acetic acid. (Hoffman, et. al. 1998)

Analysis of "Snowball Earth Hypothesis"

The data obtained from cap carbonates deposited where glaciers melted and sea level climbed, carbonates deposited on glacier submerged karst, forming guyots, other areas, iron rock deposits were found that aged (540 ma?) (Hoffman, et. al. 2002)

The cap carbonates are located above glacial strata that form a shape knife edge boundry. The Namibia cap carbonates formation is a rocky cliff along the Namibia skeleton coast. There superposition of the glacial strata to cap carbonates disconfroms.

The specimens gathered from that strata are uniformity to Neopaleozoic glaciation samples from other excavations. The comprehensive data help scientist conclude Neopaleozic glaciers had existed for 100 million years, it's believed the glaciers formed when animal life radiated and then mass extinction followed.

The enormity of the glaciation cover makes a vivid picture of a Earth receiving Sun light without atmosphere to retain heat. There was no data of Snowball Earth glacial succession. What glaciers and where had the first occurred -- what glaciers had rescinded eventually melting into water.

The research had established the initial span of glaciation, the nature of the rock, and perhaps why massive glaciation happened. Scientist established through mathematical models, based on the rock samples, a phenomenon of ice-albedo feedback. Geographic surfaces that reflect the Sun's incoming energy. (Hoffman, et. al. 2000)

This model was used to describe atmospheric conditions that can initiate Snowball Earth.

Discussion

Research concluded that DELTA 13 CARBON of -5% indicated there was no photosynthesis on earth. Thus, no biological life existed in Snowball Earth. (Cold) Iron rock deposits also proved oxygen wasn't present to oxidize iron, Therefore a Snowball earth was glaciated.

(Hoffman, et. al. 2002)

The DELTA 13

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