Archaean-erarocks near Tirumala in Andhra Pradesh (India).TheArchaean follows on from the Hadean as
Archaean-erarocks near Tirumala in Andhra Pradesh (India).TheArchaean follows on from the Hadean as the first true geological eonof the Earth. During this time, the Earth’s crust cooled down enoughthat rocks and continental plates could form.TheEarth was very different to today. It had a reducing atmosphere (inwhich oxidation was prevented) that was probably full of gases suchas ammonia and methane – toxic to most of Earth’s life today.Itwas during the Archaean that life first appeared on Earth. Theoldest fossils are bacteria microfossils, and they are 3.5 billionyears old. All life during the Archaean was bacterial.Stromatolitesare colonies of protosynthetic bacteria. Early Archaeanstromatolites have been found in South Africa and Western Australia. Their numbers increased during the Archaean, but decreased during thefollowing Proterozoic Era. They are not common today, butstromatolites can be found in Shark Bay in Western Australia. -- source link
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