Tag Archives: stabilized

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 ...

Bedforms on crater rims

A Piece of Mars: Dunes and ripples most commonly form in topographic lows. But not in this 0.96x0.54 km (0.6x0.34 mi) scene. Here, and in other places on Mars, these bedforms (called TARs) form on plains, and sometimes appear to ...

Dunes and rock hurdles in Gale crater (3D)

A Piece of Mars: Wind from the upper left is blowing dark dunes toward the lower right in this 1.92x1.08 km (1.19x0.67 mi) anaglyph (if you don't have your red/blue 3D glasses handy, you can also check out the black ...

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) ...