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The Archean Eon and the Hadean

The Archean Eon and the Hadean

It was early in the Archean that life first appeared on Earth. Our oldest fossils date to roughly 3.5 billion years ago, and consist of bacteria microfossils.

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The Proterozoic Eon

The Proterozoic Eon

The period of Earth's history that began 2.5 billion years ago and ended 542.0 million years ago is known as the Proterozoic, which is subdivided into three ...

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