The "early Earth" is a term usually defined as Earth's first billion years, or gigayear. On the geologic time scale, the "early Earth" comprises all of the Hadean eon (itself unofficially defined), as well as the Eoarchean and part of the Paleoarchean eras of the Archean eon.

This period of Earth's history, being its earliest, involved the planet's condensation from a solar nebula and accretion from meteorites, as well as the formation of the earliest atmosphere and hydrosphere. It was also defined by the emergence of life and, later, photosynthesis. The earliest supracrustals (such as the Isua greenstone belt) date from the latter half of this period, about 3.8 gya, around the same time as peak late heavy bombardment.

[edit] See also

• History of Earth

[edit] References

• Bleeker, W.. "Toward a "natural" Precambrian time scale". in Felix M. Gradstein, James G. Ogg, and Alan G. Smith. A Geologic Time Scale 2004. Cambridge University Press. ISBN 0-521-78673-8. 

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