Snowball Earth, also known as Makganyene, was an ice age of enormous proportions, probably the most extreme ever to occur on Earth. Average temperatures dropped by 45°C, and perhaps the entire planet became a vast ice sheet, reaching the equator. The oceans froze for 800 meters at high latitudes, and perhaps tens of meters even at the equator. Yet, in several places, liquid water must have remained, allowing life to survive, at least cyanobacteria. At the end of the Snowball Earth episode, the oxygen concentration in the atmosphere increased from 0% to 1%.
