Shadows behind boulders

A Piece of Mars: Bright material (either dust or sand) has accumulated in the lee of wagon- to car-sized boulders in this 0.96×0.54 km (0.6×0.34 mi) scene. It’s perhaps something like the Rocknest sand shadow that Curiosity visited a few years back. The wind blows from lower right to upper left, carrying along sediment that

Aeolian shoreline

A piece of Mars: On the left is a steep slope leading to a hill. On the right are waves – but not waves of water or any other kind of liquid. These are dunes or very large ripples, blown by the wind into intricate patterns. Sharp eyes might spy boulders that have rolled downslope

Textured gullies

A piece of Mars. These are gullies on a martian hillside (upslope is to the upper right). Water may be what forms the channels, carrying soil and rocks downslope. The textured pattern of the lower slope is caused by the wind forming ripples on loose sediment that has been transported partway down the hill. (HiRISE

Holes around rocks

A piece of Mars: This scene (509×382 m, or 1670×1253 ft), aside from showing some lovely rippled dunes, has many car-sized boulders in it. Some are surrounded by ditches in the sand, like little moats. Why? The sand is blown away from the ground as wind impacts the rocks. My colleague Mark Bishop has studied