the earliest eon in the history of the Earth from the first accretion of planetary material (around 4,600 million years ago) until the date of the oldest known rocks (about 3,800 million years ago); no evidence of life

The earliest subdivision of the Precambrian, spanning the time between the formation of the Earth, about 4.5 billion years ago, and the start of the Archaean era, 3.8 billion years ago. This interval predates the period of true geologic time since no rocks of this age are known on Earth, with the exception of a few meteorites.

The earliest eon in the history of the Earth from the first accretion of planetary material until the date of the oldest known rocks. The name "Hadean" derives from the Greek Hades "Hell".

The oldest of the Precambrian eons; the time between Earth's origin and the formation of the first rocks that have been preserved.

(See Timetable of the Precambrian)