ERA

PERIOD

EPOCH

ATOMIC TIME (Millions of years ago)

CENOZOIC

QUATERNARY

Holocene

Pleistocene

2-3

TERTIARY

Pliocene

12

Miocene

26

Oligocene

37-38

Eocene

53-54

Paleocene

65

MESOZOIC

CRETACEOUS

Late and Early

136

JURASSIC

Late, Middle, and Early

190-195

TRIASSIC

Late, Middle, and Early

225

PALEZOIC

PERMIAN

Late and Early

280

CARBON-

IFEROUS

Pennsylvanian

Late, Middle, and Early

345

Mississippian

Late and Early

DEVONIAN

Late, Middle, and Early

395

SILURIAN

Late, Middle, and Early

430-440

ORDOVICIAN

Late, Middle, and Early

500

CAMBRIAN

Late, Middle, and Early

570

PRECAMBRIAN

3600+