Hills, boulders, and wind

A piece of Mars: In the lower left of the image, a small hill stands above a plain partly covered by stabilized ripples. Boulders have rolled down the hill as it slowly erodes. If these ripples aren’t ever activated by the wind again, they will one day be completely buried by sediment eroded from this and other surrounding hills. (HiRISE ESP_031215_1830, NASA/JPL/University of Arizona)