This image shows a central swath of a well preserved crater on the volcano Alba Patera. The crater has steep walls and no large superposed craters.

The mounds of material located adjacent to the walls probably fell there during the late-stages of crater formation. The center of the crater contains a central pit that has potential fluvial features that might have formed from water released in the impact melt.

There are abundant coalesced pits near the central depression. These also might have formed from volatiles escaping from impact melt.
Written by: Kelly kOLB

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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.