Vast ocean once covered Mars, say scientists | Science | The Guardian

Vast ocean once covered Mars, say scientists | Science | The Guardian: "Scientists have revived arguments over whether there was once an ocean on the surface of Mars by claiming that their analysis of existing data supports the hypothesis that water covered much of the red planet's northern hemisphere 3.5bn years ago.

They believe their study of apparent marine deltas and valley networks in the journal Nature Geoscience bolsters the possibility that up to a third of Mars was under about 30 million cubic miles of water."