EónEn geology, an Eon refers to each of the major divisions of time in the history of the Earth from the point of view of geological and paleontological. The category of higher rank is the supereón and the rank immediately below are the eras. The limit after an EON and the future must be fundamental change in the history of living organisms. Although the proposal made in 1957 to define an Aeon as a unit of time equal to one billion years, the idea was not accepted as a unit of measure in itself and is rarely used to specify an exact period of time, but it is used as a large but arbitrary amount of time.
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