HiRISE image PSP-001916-2220 shows surface features on the northern plains of Mars.

Light-toned mounds occur across the image. The northern part of the image is dominated by small knobs or patches, while there are features hundreds of meters across to the south. The larger features frequently have one or more craters and an irregular shape; it has been proposed that these features are mud volcanoes, which erupt mud instead of lava. On Earth, mud volcanoes usually form in conditions of tectonic pressurization or rapid burial of sediments.

At high resolution, the knobs show some fine lineations which may be wind-blown material, but are otherwise very smooth. In between the mounds the surface is rough and rich in boulders. The few boulders on the mounds were likely ejected from nearby impact craters. Information like this from HiRISE images provides useful constraints on the formation and material of these knobs and cones.
Written by: Colin Dundas

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.