Chaocian: 0 - 250 Myr
Peftonician: 250 - 500 Myr
Vrasmian: 500 - 750 Myr
Vrochian: 750 - 1000 Myr
Pagocian: 1000 - 1500 Myr
Lyonian: 1500 - 1700 Myr
Omician: 1700 - 1900 Myr
Ostrician: 1900 - 2100 Myr
Eocian: 2100 - 2185 Myr
Iremian: 2185- 2285 Myr
Ostrician: 2285 - Current Myr