The contour lines are superimposed upon high- resolution images of Mars, taken by the High- Resolution Stereo Camera (HRSC) onboard Mars Express. On Earth, such maps are used by hikers and planning authorities.
The researchers chose the Iani Chaos region because of its major topographical interest. It is covered in individual blocks and hills that form a chaotic pattern across the landscape.These ‘islands’ of rocks are likely all that remains of a previous surface of Mars. The areas in between the islands collapsed when cavities formed below the surface. Initially these cavities may have been supported by the presence of ice, which melted due to volcanic heat. As the water flowed out into Ares Vallis, towards the northern lowlands of Mars, the landscape collapsed and formed the Iani Chaos region we see today. The contour lines help the eye to understand the morphology of the surface shown in the images.”