Geologic Time Scale

For a more detailed version of the geologic time scale, see the University of California (Berkeley) Museum of Paleontology's excellent Web Geological Time Machine. For a review of the concept of geologic time and how it is measured, see the USGS publication "Geologic Time."

Cenozoic Era (65 million years ago to present)

Quaternary Period (1.8 million years ago to present): Holocene Epoch (8,000 years ago to present); Pleistocene Epoch (1.8 million to 8,000 years ago)
Tertiary Period (65 to 1.8 million years ago): Pliocene Epoch (5.3 to 1.8 million years ago); Miocene Epoch (23.8 to 5.3 million years ago); Oligocene Epoch (33.7 to 23.8 million years ago); Eocene Epoch (55.5 to 33.7 million years ago); Paleocene Epoch (65 to 55.5 million years ago)

Mesozoic Era (248 to 65 million years ago)

Cretaceous Period (145 to 65 million years ago)
Jurassic Period (213 to 145 million years ago)
Triassic Period (248 to 213 million years ago)

Paleozoic Era (544 to 248 million years ago)

Permian Period (286 to 248 million years ago)
Carboniferous Period (360 to 286 million years ago): Pennsylvanian Period (325 to 286 million years ago); Mississippian Period (360 to 325 million years ago)
Devonian Period (410 to 360 million years ago)
Silurian Period (440 to 410 million years ago)
Ordovician Period (505 to 440 million years ago)
Cambrian Period (544 to 505 million years ago)

The Geologic Time Scale

Phanerozoic Eon (544 million years ago to present)

Cenozoic Era (65 million years ago to present)

Mesozoic Era (248 to 65 million years ago)

Paleozoic Era (544 to 248 million years ago)

Precambrian Time (4500 to 544 million years ago)

Proterozoic Era (2500 to 544 million years ago)

Archaean Era (3800 to 2500 million years ago)

Hadean Time (4500 to 3800 million years ago)