How do we know about the early atmosphere?
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.
Topic: Earth Science
Keywords: Ocean, Oxygen, Atmosphere, Paleoclimatology, Sedimentary rocks
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.