Europe’s Mars Express spacecraft spies ancient flood plains on the red planet, where water once carved a deep canyon into the surface.

The lumpy rock blocks seen here between the Iani Chaos depression and the Ares Vallis outflow channel in the Xanthe Terra region of Mars appear to be the remains of an ancient landscape that collapsed when voids formed beneath them, astronomers said.

Ice in those cavities may have been melted by volcanic heat and ebbed out into Ares Vallis, leaving behind the large, knob-like rock lumps which stand several meters high, they added.

The stark cliffs along the edge of Iani Chaos show what could be lava layers, which are easily found in other parts of Xanthe Terra.

This perspective view of Mars was generated using a digital terrain model and color data observed by Mars Express’ High Resolution Stereo Camera.

-- SPACE.com Staff

Credits: ESA/DLR/FU Berlin (G. Neukum)