Visible here are gullies on the northeast rim of a southern hemisphere crater. Most of the gullies are cut deeply into the crater wall and have narrow channels.

Several of the gully channels have curves—known as meanders—that might indicate that the material the gullies flowed through was easily eroded. The head of many of the gullies can be traced back to the layers exposed on the wall, suggesting that groundwater trickled out of the layers onto the slope.

The floor of the crater contains dark sand dunes as well as some arcuate ridges (wavy features) at the base of the gullies. Arcuate ridges are proposed to be evidence of gravity-driven movement of ice-rich material from the crater walls onto the floor.

Written by: Kelly Kolb

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.