The High-Resolution Stereo Camera (HRSC) onboard the ESA spacecraft Mars Express obtained images focusing on a depression that displays a crater at the end of the long, winding valley, Mamers Valles.
The data was obtained on 5 August 2006 with a ground resolution of approximately 14 m/pixel. The image is centred at approximately 39° north and 17° east on the planet.
The valley of Mamers Valles is approximately 1000 km long, running along the boundary between the northern lowlands and southern highlands in the region of Deuteronilus Mensae.
Scientists term a region such as Mamers Valles ‘fretted terrain’ because it shows numerous deep and wide labyrinth-like valleys and circular depressions which often show structures formed by flowing liquid on their even floors.
The structures formed by the flows are thought to be ice-rich debris flows. They show some resemblance to block glaciers seen on Earth.
The patches of rock at the centre of the depression are thought to be remnants of rock detached from the flanks of the depression and transported into its centre (2).
The wrinkle ridges (3), as the name indicates, are formed by compressive forces acting on the surface. The dark coloured material inside the crater (4) could have formed formed in-situ or was transported by the wind.