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The eon is the geochronological time interval corresponding to the largest chronostratigraphic subdivision of the geological time scale, the eonothem. The term eon is also used in planetology to describe the history of the planets.
The history of the Earth is divided into four eons. The first three, which cover the first 4 billion years of the Earth’s history, are sometimes grouped together in a supereon called the Precambrian. For the same geological time interval, the eons and eonothems have identical names.
The four Earth eons are as follows, from oldest to newest:
https://fr.wikipedia.org/wiki/Geological_time_scale#Aeons