Proterozoic

The Proterozoic eon comes before the Phanerozoic. It was a period before the first abundant complex life on Earth. The name Proterozoic comes from the Greek "earlier life". The Proterozoic Eon extended from 2500 million years ago (mya) to 541 mya. It is the most recent part of the former Precambrian.
The Proterozoic consists of 3 geologic eras, from oldest to youngest:
The well-identified events were:
Study of these rocks shows that the eon featured massive, rapid continental accretion (unique to the Proterozoic), supercontinent cycles, and mountain building.