Global glaciation events during the Neoproterozoic era, during which Earth’s entire surface (including the equator) may have been frozen. There are three main ‘snowball’ ice-house intervals: the Sturtian and Marinoan glaciations in the Cryogenian period, and the Gaskiers glaciation in the early Ediacaran period, in total lasting from 720 million to 635 million years ago.