This image shows polar pit gullies in a depression. The gullies do not appear to have been active recently, as their channels and alcoves are covered with polygonal fractures and ripples that have formed over time. The alcoves contain boulders from eroding layers up-slope. Several of the alcoves extend to the slope rim, suggesting head-ward erosion.

The rest of the scene contains abundant polygonal ground, thought to have formed by processes involving ground ice. This image is at a high latitude where polygonal terrain is common. This feature is not found in equatorial regions, which supports a relationship with ground ice because ground ice is not stable near the equator today.

There are several muted circles on the plains in the lower half of the image; these are possibly relaxed craters. If a crater forms in ice-rich ground, the ice enhances the degradation of the crater and gives the crater a “softened” appearance.
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.