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

• 

  The geologic time scale, proportionally represented as a log-spiral with some major events in Earth's history. A megaannus (Ma) represents one million (106) years.