This image spans the floor and two walls of a pit in Noctis Labyrinthus, a system of deep, steep-walled valleys on the western edge of Valles Marineris. The valleys themselves, called graben
, are trench-like features created during stretching of the crust (in this case, most likely following volcanic activity in the nearby Tharsis region. The light-colored layers on the valley floors might contain hydrated minerals (minerals with water bound in their molecular structure). Click here
for more information and to see a larger view.
NASA / JPL / Univ. of Arizona