"Many great deluges have taken place during the nine thousand years." [Plato, "Critias" 111]
Oden, Vili, and Ve fought and slew the great ice giant Ymir, and icy water from his wounds drowned most of the Rime Giants. The giant Bergelmir escaped, with his wife and children, on a boat. Ymir's body became the world we live on. [Green]
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References: Green, Roger Lancelyn. Myths of the Norsemen, Puffin Books, Middlesex, England, 1970.