This image captures one of the cleaner portions of the interior wall of the caldera at the top of Tharsis Tholus.

Tharsis Tholus is an intermediate sized shield volcano, much smaller than giants such as Olympus Mons, but still large by terrestrial standards. While relatively dust-free, this section of the caldera wall is still extensively covered by dust that is being sculpted into curious shapes by the wind and by gravity.
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.