Archean Eon

The beginning of lifeon Earth and evidence of cyanobacteria date to 3500 mya.
Life was limited to simple single-celled organisms lacking nuclei, called Prokaryota.
The atmosphere was without oxygen,and the atmospheric pressure was around 10 to 100 atmospheres.
The Earth’s crust had cooled enough to allow the formation of continents.
The oldest rock formations exposed on the surface of the Earth are Archean.
Volcanic activity was considerably higher than today, with numerous lava eruptions.
The oceans were more acidicdue to dissolved carbon dioxide than during the Proterozoic.
By the end of the Archaean, plate tectonicsmay have been similar to that of the modern Earth.
Liquid water was prevalent, and deep oceanic basins are known to have existed.
The earliest stromatolites are found in 3.48 billion-year-old sandstone discovered in Western Australia.
The earliest identifiable fossilsconsist of stromatolites, which are microbial mats formed in shallow water by cyanobacteria.