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Scientists can't be sure about the early atmosphere and can only draw evidence from other sources. For example, volcanoes release high quantities of carbon dioxide. Iron-based compounds are present in very old rocks that could only have formed if there was little or no oxygen at the time.

scientists can't be sure about the early atmosphere and can only draw evidence from from other sources.

Explanation:

For example volcanoes relase high quantities of carbon dioxide. iron based compounds are present in very old rocks that could only have formed if there was little or no oxygen at time

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