A view of the wall terraces of Mojave Crater in the Xanthe Terra region of Mars. So-called "pitted ponds" are thought to result when material melted by crater-causing impacts is captured behind the wall terraces.
Polygonal Ridge in Gordii Dorsum Region, Mars
Ridges in Mars' Gordii Dorsum region may have originally been dunes that hardened through the action of an unknown process. Groundwater might have been involved.
Northern Hemisphere Gullies on West-Facing Crater Slope, Mars
West-facing side of an impact crater in the mid-latitudes of Mars' northern hemisphere. The crater has gullies that may have been formed by flowing water, liquid carbon dioxide or dry granular flows. Scientists continue to debate this question.
Dune Symmetry Inside Martian Crater
Dunes of sand-sized materials have been trapped on the floors of many Martian craters.
Bright Layered Deposits with Clues of Acidic Water
Color variations in bright layered deposits on a plateau near Juventae Chasma in the Valles Marineris region of Mars. Scientists believe the region likely was formed by "precipitation, surface runoff, and fluvial deposition." In other words, water - and lots of it.
Light-Toned Deposits in Noctis Labyrinthus
Dune fields in the Labyrinthus formation on Mars are visible in this image.
Branched Features on the Floor of Antoniadni Crater
A channel network which resulted after billions of years of wind erosion.
Sand Dunes and Ripples in Proctor Crater, Mars
This image shows two classes of aeolian bedforms within Proctor Crater. The ripples are composed of fine sand (less than 200 microns in diameter) or fine sand coated with coarser sand and granules