This HiRISE image shows the contact between the Hematite Bearing Plains and Etched Terrain in Northern Meridiani Planum.

The Hematite Bearing Plains (exposed at the bottom left of this image) are dark, smooth and full of dune fields. This unit is laterally extensive and the same unit that the Mars Exploration Rover Opportunity is sitting on about 400 km to the southwest. Based on observations by Opportunity, this unit is interpreted to be a thin aeolian (wind-blown) mantle of basaltic sand and hematite concretions sitting on the Etched Terrain.

The Etched Terrain in this image is split into two units. The darker unit at the top of the image is filling in a ~120 km NW-SE trending valley, while the brighter Etched Terrain in the middle of the image is stratigraphically and topographically higher than the lower Etched Terrain in the valley. This upper Etched Terrain is a plateau-forming unit with a geomorphic pattern that ranges from relatively flat plains to dissected plateaus and mesas. The lower Etched Terrain is flat with low albedo, and covered in dunes.

It is in these Etched Terrains that CRISM, and previously OMEGA, have detected hydrated sulfates, which makes a sedimentary origin seems most likely for these layered deposits of Etched Terrain found in Meridiani.
Written by: Jennifer Griffes

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.