the atmosphere

the atmosphere

1. the earth's surface used to be molten, and very hot. this means any atmosphere would have "boiled away" into space

   • eventually things cooled down enough for a thin crust to form over the earth.
     • the early atmosphere would have only been made up of carbon dioxide, water vapour and nitrogen
       • the ocean were formed when the water vapour condensed, as the earth was cooling.

2. green plants started to grow and flourish due to the vast amounts of carbon dioxide in the atmosphere

   • a lot of the carbon dioxide was dissolved into oceans
     • the rest was taken in by the plants which let out oxygen in a process called photosynthesis.
       • when the plants died they got buried under layers of sediment. the carbon they contained got locked up and turned into fossil fuels.

3. the build up of oxygen in the atmosphere killed of many of the organisms, but allowed more complex ones to evolve

   • there is virtually no carbon dioxide left in the atmosphere now

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