The Marinoan glaciation, sometimes also known as the Varanger glaciation, was a period of worldwide glaciation. A glacial episode within the Marinoan Epoch is known as the Elatina glaciation. The beginning of the Marinoan glaciation is poorly constrained, but occurred no earlier than 654.5 Ma. It ended approximately 632.3 ± 5.9 Ma during the Cryogenian period. This glaciation possibly covered the entire planet, in an event called the Snowball Earth. The end of the glaciation was caused by volcanic release of carbon dioxide and dissolution of clathrate hydrates and may have been hastened by the release of methane from equatorial permafrost.