The aureole that surrounds the western and northern sectors of Olympus Mons has puzzled Mars geologists. The most common idea is that these deposits formed as giant land slides as the volcano partially collapsed under its own weight.

This HiRISE image is centered on a dark and relatively dust-free part of the aureole. Where the dust has been stripped off, swirling bands of darker and lighter rocks are visibile. These suggest gently warped layers that have been exposed by erosion. In fact, many of the small pinnacles and mesas in this area are being eroded by the wind in the same way as layered deposits in other parts of Mars. However, there are also blocks that shed dark material, that could be broken up lava rock. The many dunes in the area suggest that much of the debris is sand sized.

Written by: Laszlo P. Keszthelyi

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.