This image shows two related features: a trough with a succession of pits in the center. The trough, formed by the roughly straight scarps trending NW-SE, is a graben, a tectonic feature formed when a block slides downwards along two faults facing each other. Graben are found in many places on Earth, with some of the best-known examples in the canyon lands area of southern Utah.

A succession of pit craters is found in the center of the graben. These are rimless pits, roughly circular, which form via collapse. On both Earth and Mars, they are commonly found in volcanic terrains. They may be due to collapse into void space left behind after propagation of a lava-filled dike.

An interesting aspect of this site is that some of the pit craters are nearly filled with some mantling material, while others have relatively smooth floors and appear empty. Since this material may have been deposited regionally, this suggests that the pits formed at different times.

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.