This HiRISE image shows an outcrop of bright material in Melas Chasma, part of the giant Valles Marineris trough system.

These troughs contain many bright deposits, often layered. The origin of these materials is still not known, but is the subject of much study because answering this question will provide important information regarding the geologic history of Mars.

In this image, some layers can be seen, but much of the surface has a strange scalloped texture. The cause of this texture is unclear, but it is likely related to the mechanism of erosion of these deposits as well as their physical nature.

These materials are being eroded by winds, forming elongated ridges called yardangs. These winds may also be responsible for the small-scale scalloped texture. Also, landslides have produced some talus cones, composed of piles of loose debris; these are visible in places, mostly near the base of the mound, as wedge-shaped features containing many boulders.
Written by: Colin Dundas

All of the images produced by HiRISE and accessible on this site are within the public domain: there are no restrictions on their usage by anyone in the public, including news or science organizations. We do ask for a credit line where possible: Image: NASA/JPL/University of Arizona

For information about NASA and agency programs on the Web, visit: http://www.nasa.gov. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.