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 Time (hā-dē'ən) Pronunciation Key
The period of geologic time between 4.6 and 3.8 billion years ago, when the solar system was forming and the Earth was solidifying. No rocks are known from this time, as they were presumably eroded or drawn deep into the Earth and melted through the processes of plate tectonics. See Chart at geologic time. |