Wind stripes

A piece of Mars: Yes, I post a lot of pictures of martian dunes with striped patterns. They’re all distinct and beautiful. So here’s another one, 480×270 m (0.3×0.17 mi) in size. These beasts moved from right to left across the scene, some of them leaving behind some stripey deposits in their wake. (HiRISE ESP_039581_1520,

Martian waves

A piece of Mars: The swirly candy stripes in these big dark dunes are layers inside that have been made visible by wind erosion (the scene is 1.5×0.9 km, or 0.93×0.56 mi). It’s rare to see the inside structure of dunes like this, but these are being eroded by wind blowing from the upper right.

Swirly rocks

A piece of Mars: Never mind the 4 m (13 ft) boulders that have fallen downslope, or the rippled sandy surfaces here. Look at those bright swirls in the ground. Those are the former interiors of sand dunes, which were trapped and incorporated into the bedrock (like dinosaur bones, but without so much rawr). The

Uniquely martian

A piece of Mars: Now here’s something that, as far as I know, can safely be labeled as “uniquely martian”. These dunes (or maybe they’re ripples) are ~25 m wide, and have formed from winds blowing from the upper left. Their upwind sides are smoothed by constant erosion from incident sand-laden winds, but their downwind

Ribbons on Mars

A piece of Mars: Bet you didn’t know there were ribbons on Mars. Long, sweeping, velvety lines, delicately frayed at the ends. These are actually ancient ripples, formed by a wind blowing from right to left. Stripes on the ripples and on the ground between them show the ancient ripple interiors, exposed by erosion. The

Spines

A piece of Mars: Here are some old dunes that look a little like vertebrae of fossils (if you think they look like dragon spines poking out of the ground then you’re playing too many video games). The white areas are stabilized and possibly lithified. The blue areas are where the dunes are being actively

Mysterious textures

A piece of Mars: Dunes don’t usually have a rough surface texture like these do. It’s not clear what’s going on. Are they ancient dunes that are being eroded? What causes this particular texture? It seems unique to high elevations on Mars. Nobody knows yet. (HiRISE PSP_009448_1670, NASA/JPL/University of Arizona)