Earth may have been a 'water world' 3bn years ago, scientists find

Chemical signatures in ancient ocean crust point to a planet without continents

Scientists have found evidence that Earth was covered by a global ocean that turned the planet into a "water world" more than 3bn years ago.

Telltale chemical signatures were spotted in an ancient chunk of ocean crust which point to a planet once devoid of continents, the largest landmasses on Earth.