This image shows a fan of material deposited on the floor of a large impact crater.

The material was transported into the crater through a valley, likely by running water. The end of the valley is visible in the west (left) part of the image. Arcuate steps visible in the east are probably due to layers of different strength or cohesion; these suggest variations in the flow conditions.

A faint trough is carved into the upper surface of the fan. This could have been cut by the last water to flow across the surface. If the channel was flowing into a lake, this might indicate a drop in lake level, leading to erosion.

The surface of the fan has many small dark spots, particularly on the upper tier. The largest spots, most commonly around impact craters, are big enough to show that these are boulders. If these boulders are original and not due to the hardening of fan sediments into rock, it suggests that the flows which deposited the fan were relatively energetic events able to carry rocks across several feet.

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.