AREAS of open water may have provided a vital haven for life on Earth when
the rest of the planet froze over about 700 million years ago.
One nagging question about the “snowball Earth” theory has been how early
animals could have survived if a thick ice sheet covered the entire planet
(Â鶹´«Ã½, 6 November 1999, p 28).
Photosynthesis would have been impossible in the dark, ice-covered oceans,
so creatures should have starved. But using a simulation that includes ice-sheet dynamics,
William Hyde of Texas A&M University has shown that stretches of open water might
have remained near…
