What are the 12 main periods in the four main eras of earths past?

Cenozoic * Recent (Holocene) * Pleistocene * Pliocene * Miocene * Oligocene * Eocene * Paleocene Mesozoic Mesozoic * Cretaceous * Jurassic * Triassic Paleozoic * Permian * Carboniferous (Pennsylvanian Mississippian) * Devonian * Silurian * Ordovician * Cambrian Pre-Cambrian You can remember this using the following mnemonic (starting at the bottom)

Camels ordinarily sit down carefully perhaps their joints creek probably early oiling will prevent permanent rheumatism. For a more detailed view of this look in the related link below.