4,600–541 Million Years Ago

Precambrian

The Precambrian encompasses the vast majority of Earth's history — over four billion years. During this immense span, the planet formed, cooled, and developed its atmosphere and oceans. The earliest life appeared as single-celled organisms around 3.5 billion years ago. For billions of years, microbial life dominated, producing stromatolites and eventually oxygenating the atmosphere in the Great Oxidation Event. The Precambrian culminated with the Ediacaran Period, when the first complex multicellular organisms — the Ediacara biota — appeared, setting the stage for the Cambrian Explosion.

Milestones

Key Events

Formation of Earth (~4,600 Mya)

Oldest known life — stromatolites (~3,500 Mya)

Great Oxidation Event (~2,400 Mya)

Snowball Earth glaciations (~720–635 Mya)

First multicellular organisms (Ediacaran, ~575 Mya)

Transition to the Cambrian Explosion (~541 Mya)

Environment

Climate & Environment

Precambrian climate ranged from extreme volcanism and high temperatures during the Hadean, through multiple glacial episodes including the dramatic Snowball Earth events of the Cryogenian, to the relatively warm conditions of the late Ediacaran.

Subdivisions