Geologic Time Scale: The Phanerozoic Eon
| Era | Period | Epoch | Dates (m.y.) |
| Cenozoic | Neogene | Holocene | 0.01-0 |
| Pleistocene | 1.8-0.01 | ||
| Pliocene | 5.3-1.8 | ||
| Miocene | 23-5.3 | ||
| Paleogene | Oligocene | 34-23 | |
| Eocene | 56-34 | ||
| Paleocene | 66-56 | ||
| Mesozoic | Cretaceous | Late Cretaceous | 100-66 |
| Early Cretaceous | 146-100 | ||
| Jurassic | Late Jurassic | 161-145 | |
| Middle Jurassic | 176-161 | ||
| Early Jurassic | 200-176 | ||
| Triassic | Late Triassic | 228-200 | |
| Middle Triassic | 245-228 | ||
| Early Triassic | 251-245 | ||
| Paleozoic | Permian | Lopingian | 260-251 |
| Guadalupian | 271-260 | ||
| Cisuralian | 299-271 | ||
| Carboniferous | Late Pennsylvanian | 307-299 | |
| Middle Pennsylvanian | 312-307 | ||
| Early Pennsylvanian | 318-312 | ||
| Late Mississippian | 326-318 | ||
| Middle Mississippian | 345-326 | ||
| Early Mississippian | 359-345 | ||
| Devonian | Late Devonian | 385-359 | |
| Middle Devonian | 398-385 | ||
| Early Devonian | 416-398 | ||
| Silurian | Pridoli | 419-416 | |
| Ludlow | 423-419 | ||
| Wenlock | 428-423 | ||
| Llandovery | 444-428 | ||
| Ordovician | Late Ordovician | 461-444 | |
| Middle Ordovician | 472-461 | ||
| Early Ordovician | 488-472 | ||
| Cambrian | Late Cambrian | 501-488 | |
| Middle Cambrian | 513-501 | ||
| Early Cambrian | 542-513 | ||
| Precambrian time | 4600-542 | ||
| Era | Period | Epoch | Dates (m.y.) |
Back to the top-level geologic time scale
Phanerozoic means "visible life," referring to the first appearance of hard-shelled fossils at the beginning of the Cambrian Period. Earlier, during Precambrian time, life consisted entirely of soft-bodied forms that are rarely fossilized. The names of the three eras in the Phanerozoic Eon mean "old life" (Paleozoic), "middle life" (Mesozoic) and "recent life" (Cenozoic).
This table shows more time units than most geologists learn in school. Students learn all the periods, but only the Cenozoic epochs.
There are a few differences between usage in America and elsewhere. American students learn a time scale with two periods, the Pennsylvanian and Mississippian, in place of the Carboniferous; elsewhere those two names are not in wide use. The International Commission on Stratigraphy compromises by calling the Pennsylvanian and Mississippian subperiods. And American geologists divide the Cenozoic Era into the Tertiary and Quaternary periods. Learn more about that on the Cenozoic Era geologic time scale.
Specialists divide the epochs further into ages. You can see the ages for each era in the Paleozoic, Mesozoic, and Cenozoic geologic time scales.
The dates and colors shown on this geologic time scale were specified by the International Commission on Stratigraphy in 2004.
