How do we know about the early atmosphere?

  • Exhibition Text

    • Among the oldest rocks on Earth are many sedimentary rocks known as banded iron formations. They formed in an atmosphere and ocean containing little or no free oxygen.

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  • For Educators

    • Topic: Earth Science

      Subtopic: Atmosphere

      Keywords: Ocean, Oxygen, Atmosphere, Paleoclimatology, Sedimentary rocks

      Audience: General

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Ontario banded iron formation

Ontario banded iron formation

This banded iron formation comes from a rock unit 60 meters thick that formed over a 50-million-year period, from 2.736 to 2.687 billion years ago.