SPACE dust found deep below central Africa has boosted the controversial idea that Earth was once completely sheathed in ice.
The “Snowball Earth” theory claims that our planet was entirely frozen over about 630 million years ago. Most geoscientists agree that the Earth cooled significantly at that time, but some favour a “Slushball Earth” scenario in which equatorial oceans did not freeze.
Bernd Bodiselitsch of the University of Vienna in Austria and his colleagues evaluated the two theories by measuring iridium levels in three cores drilled from central Africa. Iridium is a component of the space dust that continually falls…
