This HiRISE image shows a part of the Cerberus Fossae, a long system of aligned fissures. The Cerberus Fossae were the source of the youngest major volcanic eruption on Mars that covered much of the surrounding area in lava. The region has also seen much other volcanic activity.

The walls of the fissures typically reveal lava layers. At this site, they have cut through an older hill that protrudes above the surrounding plains. The layers within the hill are tilted relative to the overlying rock, which appears to drape the region and runs continuously over the hill and plains.

This tilted contact is known as an angular unconformity. It is most likely that this formed when horizontal layers were tilted by faults before the most recent volcanic eruptions, forming the irregular hills. The hills represent relatively old rock, while the smooth plains and the thin draping cover were formed more recently.

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.