Evolution of the Atmosphere

  • Created by: lh07
  • Created on: 31-07-15 12:57

Phase One

1) - Volcanoes gave out gases.

  • The Earth's surface was originally molten for many millions of years - it was so hot due to volcanic activity that any atmosphere just 'boiled away' into space. 
  • Eventually, the heat cooled down and a thin crust formed, yet volcanoes kept erupting
  • These volcanoes gave out lots of gases, including: carbon dioxide, water vapour annd nitrogen
  • According to this theory, the early atmosphere was mostly carbon dioxide and water vapour wth hardly any oxygen. We think this was how the atmosphere was created
  • The oceans were formed by the water vapour condensing, due to the Earth cooling down. 
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Phase Two

2) _- Green plants evolved and produced Oxygen

  • Green plants evolved over most of the Earth, because they were quite happy in the carbon dioxide atmosphere.
  • A lot of early carbon dioxide dissolved into oceans. The green plants also removed carbon dioxide from the atmosphere and produced oxygen by photosynthesis, causing the carbon dioxide count to minimise.
  • When plants died, they were buried under many layers of sediment, and the carbon they had removed got 'locked up' in sedimentary rocks as insoluble carbonates and fossil fuels
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Phase Three

3) _- Complex Organisms evolved.

  • The buildup of oxygen killed off some early organisms that couldn't tolerate it, but allowed more complex organisms to evolve
  • There is virtually no carbon dioxide left now
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