Major ice ages

The next well-documented ice age, and probably the most severe of the last billion years, occurred from 850 to 630 million years ago (the period) and may have produced a in which glacial ice sheets reached the equator, possibly being ended by the accumulation of such as CO₂ produced by volcanoes. "The presence of ice on the continents and pack ice on the oceans would inhibit both and which are the two major sinks for CO₂ at presentIt has been suggested that the end of this ice age was responsible for the subsequent though this model is recent and controversial.

A minor ice age, the occurred from 460 to 430 million years ago, during the and the period. There were extensive polar at intervals from 350 to 260 million years ago in South Africa during the and Periods, associated with the Correlatives are known from Argentina, also forming in the center of the ancient supercontinent Gondwanaland.

The occurred from 360 to 260 million years ago. It is named after the glacial tills found in the Karoo region of South Africa where evidence for this ice age was first clearly identified. It is thought that this ice age was largely caused by the evolution of land plants with the onset of the period. The Earth during this time was covered with an immense degree of vegetation compared to earlier times, and this caused a long term increase in planetary oxygen levels and reduction of CO₂ levels that resulted in this ice age.