Period (geology)

A period in geology is a main subunit of an era.

Thus the Mesozoic era is divided into three periods: the Triassic, the Jurassic and the Cretaceous. These periods are then further subdivided into epochs.

Period (geology) Media

Geologic time scale with proportional representation of eons/eonothems and eras/erathems. Cenozoic is abbreviated to Cz. *The image also shows some notable events in Earth's history and the general evolution of life.
The geological clock: a projection of Earth's 4,5 Ga history on a clock ("Ma" = a million years (Megayear) ago; "Ga" = a billion years (Gigayear) ago)

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