The clay-rich terrain surrounding Mawrth Vallis is one of the most scenic regions of Mars, a future interplanetary park. Here, we cut a long, oblique view into strips to see the full color coverage in more compact form.
The origin of these altered layers is the subject of continued debates, perhaps to be resolved by a future rover on the surface. We do know that these layers are very ancient, dating back to a time when the environment of Mars was wetter and more habitable, if there were any inhabitants. [More at link]