Geochronology

Source

The Precambrian (Pre-Cambrian) is an informal name for the supereon comprising the eons of the geologic timescale that came before the current Phanerozoic eon. It spans from the formation of Earth around 4500 Ma (million years ago) to the evolution of abundant macroscopic hard-shelled animals, which marked the beginning of the Cambrian, the first period of the first era of the Phanerozoic eon, some 542 Ma. It is named after the Roman name for Wales, Cambria, where rocks from this age were first studied.
The Precambrian has sometimes been referred to erroneously as an "Era", which is a subdivision of an eon
Precambrian eon
4567.17 - 542 million years ago

The geological eras

-4500 —

–

-4000 —

–

-3500 —

–

-3000 —

–

-2500 —

–

-2000 —

–

-1500 —

–

-1000 —

–

-500 —

–

0 —

Hadean

Archean

Protero
-zoic

Phanero
-zoic

Eo

Paleo

Meso

Neo

Paleo

Meso

Neo

Paleo

Meso

Ceno

Scale:
Millions of years