Tag Archives: stabilized

Ancient ripples?

A Piece of Mars: Potential signs of wind activity are everywhere on Mars. Take this 0.96x0.54 km (0.6x0.34 mi) scene, which is on bedrock dated to be several billion years old. There's a fabric of ridges trending from the upper ...

Fossil dunes

A Piece of Mars: This 1.92x1.08 km (1.19x 0.67 mi) scene shows eroded ridges that are, in fact, lithified dunes. They are so old that you might not recognize them as dunes without more context. This doesn't happen much on ...

Giant “combs” on Mars

A Piece of Mars: This 480x270 m (0.3x0.17 mi) scene shows a herd of 100-300 m fine-toothed combs grazing on the surface of Mars. Wait, what? No, it's not really combs. This is actually a landscape covered by two sets ...

Peas in a pod

A Piece of Mars: These "peas-in-a-pod" are dunes covered in long ripples (the scene is 960x480 m, or 0.6x0.3 mi). They're a bit odd, surrounded by a rippled apron. It reminds me of melted-looking dunes that are common in ...

Is it windblown or not?

A Piece of Mars: This scene is 0.96x0.54 km (0.60x0.34 mi) across. There's an old river valley running across it. The walls of the valley have been eroded and there's a washboard pattern with a wavelength of ~6m (20 ft). ...

Melty dunes

A Piece of Mars: With all due apologies to followers of the show Coupling, I have to call these things "melty dunes". This link shows what a crisp dune should look like. The dunes in this 600x450 m (0.37x0.28 mi) ...

The bright barchan

A piece of Mars: Most dunes on Mars are dark, like these and these. So why is this one bright? It's adjacent to a more typical, dark dune. It's possible that there are two populations of sand here that are ...

Changing winds

A piece of Mars: There are two sets of ripples here: tan ones and gray ones, each oriented to a different wind (scene is 300x225 m, or 984x738 ft). The gray ones sit on top of the tan ones, so ...

Swirly rocks

A piece of Mars: Never mind the 4 m (13 ft) boulders that have fallen downslope, or the rippled sandy surfaces here. Look at those bright swirls in the ground. Those are the former interiors of sand dunes, which were ...

Uniquely martian

A piece of Mars: Now here's something that, as far as I know, can safely be labeled as "uniquely martian". These dunes (or maybe they're ripples) are ~25 m wide, and have formed from winds blowing from the upper left. ...