Fuzzy dunes

Fuzzy dunes
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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

Ripples of rock

A Piece of Mars: To the upper right of this 0.85×0.6 km (0.53×0.37 mi) scene is a flat-lying plain strewn with large ripples. To the lower left is a rugged hill with gray rock laced with white veins (this might be part of an impact megabreccia identified nearby in Holden crater). Notice that some of

The corpse of a dune

A Piece of Mars: The rippled darker patch in this 600×600 m (0.37×0.37 mi) scene is the former site of a sand dune. This is one of a few “dune corpses” found just upwind of a dune field in Holden crater. The dunes are migrating to the south and east – you can see that

Mars’ corduory

A Piece of Mars: The wind on Mars likes to make textiles (unfortunately the term geotextiles is already taken for other purposes). This 1×0.6 km (0.62×0.37 mi) scene shows two different sets of ripples. The larger set has straight to wavy crests, and they’re ~18 m (~59 ft) apart, which is pretty big for ripples

Leeward and poleward

A Piece of Mars: The sharp line in this 0.625×0.625 km (0.39×0.39 mi) scene is the crest of a long dune in Mars’ southern hemisphere. The sunlit side is also the lee side: the bright streaks are thin sand avalanches (grainflows) that formed when the wind blew too much sand over the crest from the

Wind and maybe water too

A Piece of Mars: Along the right side of this 0.5×0.5 km (0.31×0.31 mi) scene is the rim of a crater – the stripes are layers exposed (and then perhaps draped by falling ejecta) as the crater formed. To the left is the crater’s interior wall, dropping downward. Deep gullies have been eroded into the

A change of fluids

A Piece of Mars: Water carved this ~800 m (0.5 mi) wide channel billions of years ago. The water dried up, and since then it’s been sand that flows through here (from the right), building up lovely dunes. A single crater on one of the dunes indicates that they’re not very active (dunes of this

Two directions

A Piece of Mars: Sometimes I just want to show the interior of a dune field, because it’s full of waves: ripples and dune crests, slip faces, all of which signs of movement. The dunes in this 0.67×0.47 km (0.41×0.29 mi) view have been made by two winds: one blowing from the top of the