Geoscientists in Scotland announced in 2004 they
had evidence to disprove the controversial 'Snowball Earth' theory
- the idea that the planet was almost completely encased in ice
just over 600 million years ago.
The team, from the University of St Andrews,
published its findings in the scientific journal Geology, after
studying rocks in the west of Scotland, Ireland, Namibia, and
California. Drs Dan Condon, Tony Prave, and Doug Benn said that they
had found evidence of sedimentary material, which could only have
been derived from floating ice on open oceanic waters.
This, they believed, indicated that Earth's oceans
could not have been frozen during the snowball years.
The controversial theory that for millions of years
the planet was entirely smothered in ice, up to one kilometre thick,
had been kicked around for more than fifty years.
It rested on the apparently anomalous evidence of
past glaciation in places that should have been much too hot - very
near the equator. Even during the most severe ice age, many
scientists thought that the ice only reached as far down as Northern
Europe and the middle of the USA.