Too steep for ripples

A piece of Mars: This 480×270 m (0.3×0.17 mi) area is a steep slope that plunges down to the upper left. A pile of dark sand, covered by brighter tan dust, clings to the hillside. Usually the martian wind blows sand into ripples, and you can see where it’s tried to do that here. But the steep slope triggers thin dark avalanches of dark sand that compete with the wind in shaping the sandy surface. (HiRISE ESP_043085_1670 NASA/JPL/Univ. of Arizona)