Tag Archives: ripples

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 ...

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 ...

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 ...

Who wins in the fight of wind vs. ice?

A Piece of Mars: This is the crest of one of the largest dunes on Mars (0.5x0.5 km or 0.31x0.31 mi). The wind mostly blows from the right, slowly pushing sand up the windward slope. But frost accumulates on (and ...

Dunes + Craters = Mars

A Piece of Mars: How do you tell when a planetary landscape shows Mars, instead of Mercury or the Moon or Europa? The easiest way to tell is to look for both craters and dunes, like what's shown here in ...

Mars’ giant sweaters

A Piece of Mars: Sometimes in the floors of small craters, the wind blows in from several directions to produce odd polygon-shaped dunes that look like crochet (maybe Mars is making sweaters for its craters - it is, after all, ...

Tortoise and hare

A Piece of Mars: There's a lot of evidence for both fast and slow movement in this 480x270 m (0.3x0.17 mi) scene. The tortoise: The rippled surface at the top is high ground: the top of a dune. Wind pushes ...

Crater ejecta on old ripples

A Piece of Mars: Mars rarely does anything without drama. Long ago in this 0.96x0.54 km (0.6x0.34 mi) scene, large ripples formed and then, presumably, lithified (turned into rock). Some time after that, an impact formed the crater in the ...

Steno’s principles, or “how to make sense of pretty landscapes”

A Piece of Mars: Nicholas Steno was a 19th century geologist, who came up with some principles that are still used today to guide interpretation of exposed sedimentary rocks. The principles seem a bit obvious, but then some of the ...

Them that make ripples and them that don’t

A Piece of Mars: Higher ground is to the left. You're seeing a tan layer sandwiched between two gray layers in this 0.96x0.54 km (0.6x0.34 mi) scene. Large ripples have accumulated in the lowest area to the right, which is ...