The Nili Fossae region, located on the northwest rim of Isidis impact basin, is one of the most colorful regions of Mars.
The colors over many regions of Mars are homogenized by the dust and regolith, but here the bedrock is very well exposed, except where there are sand dunes. The rocks also have diverse compositions. This region is ancient and has had a complicated geologic history, leading to interesting structures like layered bedrock, as well as other compositions.

This image of Nili Fossae was taken on Feb. 5, 2016, at 14:54 local Mars time by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter. The University of Arizona, Tucson, operates HiRISE, which was built by Ball Aerospace & Technologies Corp., Boulder, Colo. NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter Project for NASA’s Science Mission Directorate, Washington.

Image Credit: NASA/JPL-Caltech/Univ. of Arizona
Caption: Alfred McEwen Larger image