This HiRISE color image covers the floor of Holden Crater in Margaritifer Terra. Holden is one of the most interesting locations for scientists investigating the history of water on Mars, because the crater contains deep gullies carved by running water, as well as excellent examples of likely lake beds and alluvial fans (sediment deposited by streams) on its floor.

These deposits are about 3.7 billion years old and date back to a wetter period of early Martian history. Since that time the planet has generally been very cold and dry, and water has remained frozen in the polar regions or middle latitudes.

The cliff shown in this frame is located on the southwestern part of the crater floor. Many of the brightly colored, flat-lying, possible lake beds near the bottom of the cliff are each less than a meter thick. After these lake beds were deposited, a massive flood entered Holden Crater from the southwest and deposited the layer of dark boulders and gravel that are now exposed near the top of the cliff. After the lake dried up, wind eroded the surface and formed the ripples and dunes seen in the valley. The circular pits are impact craters formed by meteorite strikes onto the ancient deposits.

Note: the color in these images is enhanced; it is not as it would appear normally.

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.