Research supports 'Snowball Earth' theory

u2boy_nl writes: "A new U.S. study finds evidence for the 'Snowball Earth' hypothesis, the theory which states that the entire Earth was ice-covered for long periods 600-700 million years ago. These icy conditions (Earth's oceans frozen completely with ice more than two kilometers thick) ended violently under extreme greenhouse conditions and triggered the evolution of multicellular animal life. The Snowball Earth theory was previously assumed rather than tested and challenges long-held assumptions regarding the limits of global change.

For more on the theory see snowballearth.org and of course wikipedia"