Olympus Mons, the largest volcano in the Solar System is covered by lava flows. Most of these lava flows carried the liquid lava in open streams which geologists call channels. In some places these channels break down and the lava spreads across a broad area, like a fan. In the center of this HiRISE image, you can see the transition from well-confined lava channels into broad fans as the lava flowed down to the north.

When viewed at full-resolution, the HiRISE image shows a fuzzy pitted surface. This is caused by a thick layer of very small particles that are being moved around by the wind. It is not clear at this point in time whether these particles are predominantly dust deposited from the global dust storms or if they are mostly volcanic ash.
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.