These images were taken by the High Resolution Stereo Camera (HRSC) on board ESA’s Mars Express are of the Acheron Fossae region, an area of intensive tectonic (continental ‘plate’) activity in the past.
The images show traces of enormous stress and corresponding strain in the crust of the Red Planet. The HRSC was pointed twice at this interesting geological feature in the Acheron Fossae mountain range, during orbits 37 and 143.
The feature is situated at approximately 35º-40º North and 220º-230º East, about 1000 kilometres north of the large Olympus Mons volcano.
This perspective view of images 1-3 shows the same region including some adjacent areas to the south without vertical exaggeration. This is dominated by the curved faults, showing a highly fractured and deformed area in the central part of the Acheron Fossae.
In geological terms, this is called a ‘horst and graben’ system. When several parallel faults form, the block of crust between them drops down, forming a ‘graben’. At Acheron, an almost classical example of parallel fault-bounded grabens has formed, dissected by remnants of the pre-existing topographical heights, the ‘horsts’.