This image shows a large symmetrical alluvial fan at the mouth of a small channel along an unnamed crater. Alluvial fans with a well-defined channel source area are relatively uncommon on Mars.

This fan has a rib-like outer margin and many more terrace-like scarps upslope near the channel mouth. These terraces may indicate the outer margin of sediment deposits during each “pulse” of deposition. Further study of these types of alluvial fans may shed light on past sedimentary environments and conditions on Mars.

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.