Dan McKenzie talks about water on Mars

The surface of Mars shows the scars of a wetter and warmer past when great floods raced over its surface. But there has always been one question about this picture: where did the water come from?

A new analysis of some of the planet's surface features suggests that the flooding on Mars may be related to the geological fault lines that can be seen criss-crossing the surface.

Only 2.5 km (1.6 miles) wide

Dan McKenzie of the University of Cambridge has used computer simulations that show that magma, molten rock, moving underneath the surface can melt underground ice deposits generating vast amounts of water.

Something like 2,000 cubic km of water is needed to account for the scars on Mars.

The intrusion of magma provides a source of heat sufficient to melt ground ice, and provide a source of water for the floods.

The water would have caused catastrophic floods and then frozen again at the lowest points in the landscape.

It would then sink into the ground and the cycle would start all over again.