This image shows a portion of the southern highlands cut by Arda Valles, an ancient valley network.

The valley network is degraded as seen by the lack of obvious walls and a V-shaped bottom. The valley networks are thought to have formed by running liquid water on the surface of Mars billions of years ago, with a few being active more recently.

Arda Valles has many dunes within it and craters on top of it, which show that is has been around for long enough for craters to form. The surface that Arda Valles cuts is more cratered than the valley surface because wind has moved material into the valley throughout time such that the surface in the valley gets covered and past craters might be buried there.

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.