January 11, 2013

Bright and dark sand on a dune

A piece of Mars: A lovely little dune is right at the edge of this image, trying its best to migrate into the center of the frame. The bright sickle-shaped part of the dune is its slip face, where sand […]
January 8, 2013

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 […]
December 31, 2012

Dune cannibals

A piece of Mars: Dunes often cannibalize each other, with new dunes forming from the sand in older dunes. Here the tan dunes have formed from the sand that made up the grayish blue dunes. Notice the banding on the […]
December 19, 2012

Bye-bye, crater

A piece of Mars: On Earth, it’s typically water that erodes a landscape, as rivers cut down rocks, storms trigger landslides, and ocean waves eat away at shorelines. On Mars, it’s usually the wind that slowly grinds down a landscape. […]
December 16, 2012

Wisps

A piece of Mars: These wispy dunes look like veins on a leaf, don’t they? The thicker ones are older, and they are slowly being reworked by the younger, thinner ones. If they remain active, then the smaller ones will […]
December 11, 2012

The Painted Desert, on Mars

A piece of Mars: Small dunes or ripples in a depression provide a striking contrast with the surrounding bedrock. The sand in the dunes changes color, too, to mark off which regions have more recently been actively moved by the […]
December 6, 2012

Crescents and ripples

A piece of Mars: A lonely dune slowly makes its way (towards the upper right) across a plain. Well, look closer, it’s not all that lonely. Surrounding it on the plain are smaller streaks that are ripples, which also once […]
November 25, 2012

And the wind blew on

A piece of Mars: Small dunes (or possibly ripples) are likely no longer moving in today’s winds. Or are they? Dark splotches on their upper (northern) sides suggest some kind of wind scour has recently occurred. Winds blow, create dunes, […]
November 20, 2012

Generations of wind-blown landscapes

A piece of Mars: Some places on Mars highlight just how effective the wind is at sculpting the surface. This is a good example. Dark and light stripes on the right show not one but two successive influxes of sand: […]