Paleoproterozoic Era

Increase in Earth's oxygen

The Paleoproterozoic Era is first era in the Proterozoic Eon, occurring after the Neoarchean Period, and before the Mesoproterozoic Era. This era accounts for 20% of Earth's geological history.

Geologic Age

2,500–1,600 million years ago

Subdivisions

Statherian Period: 1,800–1,600 Ma
Orosirian Period: 2,050–1,800 Ma
Rhyacian Period: 2,300–2,050 Ma
Siderian Period: 2,500–2,300 Ma

Eon

Proterozoic

What happened during this time?

Geochemical

Continents and crust stabilized
- Supercontinent, named Columbia, starts to form (1.5-2.0 Ga)
The atmosphere was dominated by methane, nitrogen, ammonia, and carbon dioxide
- Oxygen levels were extremely low, but starting to increase by the end of this era
The Earth was closer to the sun, but it was 70% weaker than today.
A "day" was approximately 20 hours, and there were 450 days to an annual cycle (Feulner, 2012)

Biological

Cyanobacteria flourish along coastlines
First reported green sulfur bacteria
First acritarchs appear around 1.8 Ga
Many anaerobic bacteria go extinct
First possible eukaryotes (Grypania) arise around 2.1 Ga

Above: A stromatolite, layers of fossilized cyanobacteria from the Paleoproterozoic

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