The Cryogenian Period was the second of the three periods in the Neoproterozoic Era. It lasted from about 720 million to about 635 million years ago. It came after the Tonian Period and before the Ediacaran Period. Its beginning was defined as the start of the first glacial episode after 750 million years ago. The period is especially known for long intervals when ice covered much, and perhaps all, of the surface of Earth.
verifiedCite
While every effort has been made to follow citation style rules, there may be some discrepancies.
Please refer to the appropriate style manual or other sources if you have any questions.
Select Citation Style