This image covers part of the central uplifted region of an unnamed crater in Phlegra Dorsa.

This complex crater is approximately 30 kilometers (about 18 miles) in diameter and is centered at 23 N latitude and 176 E longitude. The transition from a simple bowl-shaped crater to a complex crater exhibiting central peaks or pits, flat floors and terraced walls takes place in craters that are larger than about 8-10 kilometers (or roughly 5-6 miles) in diameter on Mars. Because the central uplifts of complex craters expose rocks and materials that originated deep below the surface, researchers can use these regions as possible "windows" to view the rocks beneath the surface.

A northeast-southwest linear valley or trough transects this region dividing the uplift in two. This valley, or lineation, may have resulted from processes occurring during the uplift event or subsequent to crater formation. When seen at HiRISE resolution the center of this valley seems to bisect what may be a small (less than a kilometer wide) central pit.

Written by: Shawn D. Hart and Ginny Gulick

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.