- (geology) The geologic eon from about 4,600 to 3,800 million years ago; marked by the formation of the first rocks.
1998, Graham R. Thompson & Jonathan Turk, Introduction to Physical Geology, page 150:
- It may be that erosion or metamorphism destroyed traces of Hadean life, or that Hadean time preceded the evolution of life. In any case, Hadean time is not amenable to subdivision based on fossils.
Hadean — see Hadean