Geologic Time Scale: Precambrian Time
| Eon | Era | Period | Dates (m.y.) |
| Phanerozoic (post-Precambrian time) | 542-0 | ||
| Proterozoic | Neoproterozoic | Ediacaran | 630-542 |
| Cryogenian | 850-630 | ||
| Tonian | 1000-850 | ||
| Mesoproterozoic | Stenian | 1200-1000 | |
| Ectasian | 1400-1200 | ||
| Calymmian | 1600-1400 | ||
| Paleoproterozoic | Statherian | 1800-1600 | |
| Orosirian | 2050-1800 | ||
| Rhyacian | 2300-2050 | ||
| Siderian | 2500-2300 | ||
| Archean | Neoarchean | 2800-2500 | |
| Mesoarchean | 3200-2800 | ||
| Paleoarchean | 3600-3200 | ||
| Eoarchean | 4000-3600 | ||
Back to the top-level geologic time scale
"Precambrian" is a long-established, informal name for the 4 billion years of Earth history before hard-bodied organisms arose at the beginning of the Cambrian Period, earliest division of the Phanerozoic Eon. Aside from the names of the eons and the Ediacaran Period (also called the Vendian), few of the terms in this geologic time scale are yet in wide use.
Whereas later geologic history is minutely documented by fossils showing the evolving succession of living things, Precambrian time is almost entirely divided by absolute numerical ages of rocks. Nonetheless, the end of the Archean marks a distinct change in the Earth, roughly at the time atmospheric oxygen first appeared. (Read more about the Archean Eon and the Proterozoic Eon.) Archean and Proterozoic rocks are exposed in the continents' ancient central regions, but they make up a small fraction of Earth's total surface.
The dates and colors shown on this geologic time scale were specified by the International Commission on Stratigraphy in 2004.
