Scanning across several kilometers of relief, this image shows a cliff along a light-toned layered deposit in Valles Marineris. This particular cliff was targeted because of the excellent exposure of layering and the identification of the minerals kieserite (a mineral containing magnesium) and hematite (an iron oxide).
The hematite appears in the darker low-lying region near the lower left of the image and the kieserite is associated with the light-toned layers. The fact that these minerals are found here with a layered deposit suggests that water may have been involved in the deposition of these minerals and the layers.
Erosion by wind has carved V-shaped patterns along the edges of many of the layers. The layers appear friable (easy to erode) so this is why wind can carve deep grooves along a steep cliff such as visible here. The top of the layered deposit ( upper part of image ) is smooth and relatively dark because it is covered by debris laid down by the wind, dust and other fine materials.
The cliff has stronger winds flowing up and down it, plus the effects of gravity, so airborne debris can be shed downslope to expose the fresh brighter layered deposit. Written by: Cathy (9 April 2008)
This is a stereo pair with PSP_007456_1740 .
More info and image formats at http://hirise.lpl.arizona.edu/PSP_007166_1740
Image: NASA/JPL/University of Arizona