Paleoproterozoic

The most significant event of the Paleoproterozoic is the Great Oxidation Event, during which oxygen levels in the Earth’s atmosphere increased dramatically due to the photosynthetic activities of cyanobacteria. This rise in oxygen not only allowed for the eventual evolution of aerobic organisms but also triggered the formation of large deposits of iron oxides, forming banded iron formations (BIFs). The GOE also likely caused a mass extinction of anaerobic life forms that were unable to survive in oxygenated environments. 

Tectonic activity during this period resulted in the formation of significant geological features, such as the supercontinent Columbia (or Nuna), which formed around 1.8 billion years ago. The first widespread glaciations also occurred during the Paleoproterozoic, exemplified by the Huronian glaciation (approximately 2.4 to 2.1 billion years ago), which may have been one of the most severe ice ages in Earth’s history. 

The Paleoproterozoic also saw the emergence of the first complex cells (eukaryotes) that contained membrane-bound organelles. These early eukaryotic organisms would later give rise to more complex multicellular life forms.