Layered Sediments in Valles Marineris

Sediments rich in hydrated sulfates may have filled central Valles Marineris, but debates persist as to how these deposits grew or formed.

If they formed from deposition in a deep lake then the layers should be nearly horizontal. If the layers formed from airfall deposits such as volcanic pyroclastics or windblown dust, then the layers should drape over the pre-existing topography.

Another possibility is that the layers were deformed by slumping. Stereo topographic data can be used to test these hypotheses. The cutout shows an area at full resolution. There are no detectable color variations within these layers, suggesting a uniform composition or the presence of a thin cover of dust over all surfaces.

The map is projected here at a scale of 50 centimeters (19.7 inches) per pixel. (The original image scale is 56.4 centimeters [22.2 inches] per pixel [with 2 x 2 binning]; objects on the order of 169 centimeters [66.5 inches] across are resolved.) North is up.

This is a stereo pair with ESP_072836_1725.

The University of Arizona, in Tucson, operates HiRISE, which was built by Ball Aerospace & Technologies Corp., in Boulder, Colorado. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the Mars Reconnaissance Orbiter Project for NASA's Science Mission Directorate, Washington.