Chaotian (geology)

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In the geologic record the Chaotian eon or era is unofficially proposed to denote the time preceding the solidification of the Earth's crust and the formation of Earth's moon. It is named after Chaos, the primeval void in Greek mythology.

According to first proposal, it precedes the Hadean eon and is the earliest eon in Earth's history as a planet. The end of the Chaotian was marked by the hypothetical collision of the proto-Earth and a planet-sized body named Theia, leading to the formation of the Moon.[1]

Alternatively it is defined as the first era of the Hadean eon, before the formation of the first crust on the Earth. As of 2012 it is considered to be part of the general revision of the Precambrian time scale.[2]


This geological era designation was proposed by NASA scientists at the Ames Research Center in 2010 to formalize terminology in the earliest stages of Earth's history.[3]

The NASA proposal divides the Chaotian into the Eochaotian and Neochaotian eras, which are in turn proposed to be divided into the Nephelean and Erebrean, and Hyperitian and Titanomachean periods, respectively.[3]


  1. ^ Fox, Stuart (January 7, 2010). "NASA Scientists Classify the Time Before Earth Existed: the Chaotian Era". Popular Science. Retrieved 30 July 2013. 
  2. ^ Gradstein, F.M.; Ogg, J.G.; Schmitz, Mark; Ogg, Gabi (2012). The Geologic Time Scale 2012. Elsevier. pp. 360–364. ISBN 0444594485. 
  3. ^ a b Goldblatt, C.; Zahnle, K.J.; Sleep, N.H.; Nisbet, E.G. (2 February 2010). "The Eons of Chaos and Hades" (PDF). Solid Earth.