Ha·de·an Time  (hā-dē'ən, hā'dē-)  n. The geological time period during which Earth formed, from the start of the solar system (4.6 billion years ago) until accretion, impact, and local melting led to stable Earth-Moon orbits and the oldest Earth rocks (3.8 billion years ago). Also called Hadean Eon. See Table at geologic time. [AfterHades (from the intense heat during part of this period).] |
| hadean eon | |
noun | |
| 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 [syn: Hadean] |