4700–4600 million years ago
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 the earliest era within the eon of Hadean. It lasted 196 million years, at to the beginning of the Zirconian era, . It is named after Chaos, the primeval void in Greek mythology. The Chaotian sets in with the emergence of Earth at 4.6 billion years ago. Its upper limit and thus the transition to the Zirconian era is defined by the occurrence of the first conservation capable mineral. These are zircon, the oldest mineral in the Jack Hills of Narryer Gneiss Terrane in Western Australia (Yilgarn craton) found and were dated 4,404 ± 8 million years ago 
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.
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 a proposed revision of the Precambrian time scale.
The NASA proposal divides the Chaotian into the Eochaotian (4.7-4.65 Gya) and Neochaotian (4.65-4.6 Gya) eras, which are in turn proposed to be divided into the Nephelean (4.7-4.68 Gya) and Erebrean (4.68-4.65 Gya), and Hyperitian (4.65-4.62 Gya) and Titanomachean (4.62-4.6 Gya) periods, respectively. As of May 2017[update], this has been adopted by the IUGS.
Timing of events
The exact date of the birth of our solar system (and the earth) is still controversial. Calcium-aluminium-rich inclusions (CAI), the first condensate from the planetary orbit, were dated to 4,567.30 ± 0.16 million years ago by the uranium-lead method.
Manganese-chromium dating of chondrules revealed an age of 4.571 billion years ago. In 1979 dating of the Mundrabilla iron meteorite of Western Australia using the argon method determined an age of 4,570 ± 60 million years ago.
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