Proterozoic Eon

Comprising of the Paleoproterozoic, Mesoproterozoic and Neoproterozoic Eras, This eon spans from 2.5 billion years ago to 541 million years ago lasting almost 2 billion years.

During the beginning of this eon, cyanobacteria rapidly reproduced and photosynthesized turning a lot of carbon dioxide to oxygen. This oxygen reacted with the iron in the oceans, filling the oceans with iron rust BIFs, turning the oceans blood red. Later, there was no longer enough iron to hold onto the oxygen, and it escaped into the atmosphere. That oxygen formed the ozone layer. Nearly all of the carbon dioxide turned into oxygen, turning earth into a snowball earth.

The snowball earth quickly recovered after 300 million years. Then, supercontinent Columbia formed. For the next billion years, climate remained notably stable. This period of time from 1.8 billion years to 800 million years ago was called "The boring billion". During this period, supercontinent Rodinia formed, but broke apart. The rocks that became exposed sucked up more carbon dioxide from volcanoes, turning earth into a second snowball earth.

After that recovered, the two halves of Rodinia reunited around the South Pole forming supercontinent Pannotia. However, it broke apart during the end of the eon just as animals started to appear, as Laurentia rifted away from the rest of the supercontinent. Finally, the End-Ediacaran extinction event took place to end the eon.

Imagine living during the middle of the Proterozoic Eon! There would be no plants, no animals, just water, land and bacteria!