As a result of the new abundance of oxygen in the atmosphere, BIFs may have caused the entire planet's oceans to rust.
# Metadata
Title: Oceans Turn Red Movietime: 4:32 Geographical Time: 2450 Ma
Following the Great Oxygenation Event, excess oxygen released by cyanobacteria reacted with dissolved iron in Earth's oceans. This reaction formed vast deposits of banded iron formations (BIFs), pulling iron out of the oceans and precipitating it to the seafloor.
The process may have turned entire oceans reddish-brown — a planetary-scale rusting event — leaving behind geological records that persist to this day.