Tag Archives: dunes

Black and tan

A Piece of Mars: Dunes in the top row in this 0.73x0.47 km (0.46x0.29 mi) scene are dark but those in the lower row are brighter. Why? They're all probably made out of the same kind of sand, which is ...

Leeward and poleward

A Piece of Mars: The sharp line in this 0.625x0.625 km (0.39x0.39 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 ...

Exhumed dunes!

A Piece of Mars: The large dunes in the middle of this 375x450 m (0.23x0.28 mi) scene run along a valley (the small dunes at top and bottom are on high ground). What's amazing about this is that the ends ...

Mars’ giant bubble wrap

A Piece of Mars: This 0.7x0.5 km (0.43x.31 mi) scene shows Mars' giant yellow bubble wrap, with each "bubble" about 100 m across (seriously, don't you want to pop them?). These are actually a type of dune called a "dome ...

Reversing slip faces

A Piece of Mars: This 523x750 m (0.32x0.47 mi) scene shows a large dune. It's quite colorful for some reason, although it's partially false-color. What caught my eye is that the slip face on this dune has reversed direction, which ...

The real tetrahedrons of Mars

A Piece of Mars: The real tetrahedrons of Mars are dunes, built by winds blowing sand from more than one direction. This 0.5x0.5 km (0.31x0.31 mi) area shows a dune formed from two winds that are about 90 degrees apart: ...

Dunes fighting for survival

A Piece of Mars: Having a bad day? You're in good company with these dunes in this 0.96x0.48 km (0.6x0.3 mi) scene. The gray barchanoid dunes are covered in ripples, as the wind valiantly tries to push the sand to ...

Is it an old fossil barchan dune?

A Piece of Mars: There are many barchans on Mars, those lovely isolated crescent-shaped dunes. In a few places there are what looks like ancient preserved barchans, now lithified. The mound in the center of this 0.96x0.54 km (0.6x0.33 mi) ...

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 0.67x0.47 km (0.41x0.29 ...

Where on Mars is this dune?

A Piece of Mars: This 0.48x0.27 km (0.3x0.17 mi) scene shows a rotund barchan dune. Can you tell from looking at it where on Mars it might be? To me the most obvious feature are the bumpy piles at the ...