phase 1
volcanoes gave out steam and CO2.
volcanoes gave out steam and CO2.- the earths surface was originally molten for many millons of years.Finally is cooled and a thin crust formed, volcanoes kept erupting, releasing carbon dioxide, steam and ammonia.early atomsphere mostly CO2 and water vapour later formed the oceans.
phase 2
green plants envolved and produced oxygen.
CO2 dissolved into the oceans. Green plants started to evolved.Nitrogen gas was put into the atmosphere- it formed ammonia reacting for oxygen and was released by denitrifying bacteria.
phase 3
ozone layer allows evolution of complex animals.
the build up of oxygen in the atmosphere and killed off early organisms= more complex organisms.oxygen=ozone layer.which blocked harmful rays=more complex orgainisms.
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