Where dune fields begin

This is the upwind edge of a dune field (825×625 m, 0.51×0.39 mi). Winds blow down a cliff (offscreen) from the lower right, blowing sand toward the upper left. Elongated dunes have formed parallel to the resultant wind direction, only avalanching into slip faces once enough sand has piled up (there are two slip faces

Mars’ “Type A” wind

The busy, busy wind has moved a lot of things to make this 0.6×0.85 km (0.37×0.53 mi) landscape. First it built a big dark dune, covering it and the surrounding surface with ripples. Then it dumped a bunch of bright yellow dust all over everything, maybe the result of a nearby dust storm, or maybe

Smash! Whoosh…

A Piece of Mars: The dark splash pattern in this 0.9×0.9 km (0.56×0.56 mi) scene (click on it for a better view) is the site of an impact crater that appeared between images sometime between August 2006 and March 2010 (Smash!). The main crater is ~7 m (23 ft) across. Impacts smash a little ways

Arnus Vallis, Mars

A Piece of Mars: This is a section of Arnus Vallis (scene is 1.25×1 km, 0.78×0.62 mi). It’s a >300 km long valley that was carved out, not by water, but by lava, long ago. Since then the wind has taken over. The left wall of the valley seems to have layers etched into high

Varying wind directions

A Piece of Mars: This 0.5×0.4 km (0.31×0.25 mi) scene shows two dunes near the north pole. The shape of the dunes indicates two main winds: one blowing left to right (which makes slip faces on the right side, one of which still has some bright white ice on it), and a secondary wind blowing

Dunes with comet tails

A Piece of Mars: The north polar dunes in this 575×325 m (0.36×0.2 mi) scene are made of dark sand covered by bright winter frost (which will soon sublimate away, as this image was taken in late spring). To the right of the dunes extend pale yellow bumpy hills, making the dunes look like they

Fuzzy dunes

A Piece of Mars: The dunes (or maybe they’re ripples) in this valley appear to be fuzzy (the view is 625×775 m, 0.39×0.48 mi). They’re not really fuzzy, but it’s not actually clear what’s going on. They seem to have smaller ripples superposed on them, and maybe bright dust has settled into the troughs between

Buried by ejecta

A Piece of Mars: To see this one well you’ll have to click on the image. At the lower right, a 240 m (787 ft) diameter crater formed when a bolide hit the surface, throwing out ejecta on the surrounding terrain. Zooming in, you can see that the ejecta has a distinctive rough surface. Farther