Period (geology)
A period in geologic time scale 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.
A period in geologic time scale 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.