Mesoarchean Era

Direct evidence of life

The Mesoarchean is the third era in the Archean Eon, occurring after the Paleoarchean Era, and before the Neoarchean Era.

Free oxygen present in the oceans, possibly formed from cyanobacteria around 3.2 billion years ago (Satkoski et al., 2015)
Evidence for chemical weathering of rocks leading to soil formation that occurred in the presence of O2 at least 3.02 billion years ago (Deane & Crowley, 2014)
The oldest known glaciation event, Pongola, starts toward the end of this period (~2.9 Ga)
Extensive cratonization events have never been repeated in the history of the Earth.
- The first supercontinent, Vaalbara, broke up during this time
- The Supercontinent, Ur, may have originated during this time (~3.1 Ga)
- Ur existed for a very long time, joining with other cratons to later form Rodinia and, even later, Pangaea.
Atmospheric oxygen levels remained very low as the oxygen continued to be used up in oxidizing minerals on the earth's crust and in the sea
- Oldest Banded Iron-Ore formations are from this time

First direct evidence of life on Earth
- Anaerobic prokaryotes
- Diversification of stromatolites on Earth
Potentially complex microfossil of microplankton (House et al., 2013)
Possible life on land by 3.0 Ga (Retallack et al., 2016)

Above: Living stromatolites at Shark's Bay, Australia