Tag Archives: crossbedding

Fuzzy dunes

A Piece of Mars: The dunes (or maybe they're ripples) in this valley appear to be fuzzy (the view is 625x775 m, 0.39x0.48 mi). They're not really fuzzy, but it's not actually clear what's going on. They seem to have ...

The corpse of a dune

A Piece of Mars: The rippled darker patch in this 600x600 m (0.37x0.37 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 ...

Cross-strata or not?

A Piece of Mars: Sand dunes are one of the few sedimentary phenomena that leave behind layers that aren't horizontal. They tend to have a characteristic lean to them (and we call them cross-strata). So when I see something that ...

Dunes in a colorful hole

A Piece of Mars: Gray dunes have migrated over reddish rock, moving toward a narrowing cleft surrounded by tall tan cliffs. Bright lines on the dunes are exposed internal layers (bones of the dunes, really) that show you where the ...

The trail of a dune

A Piece of Mars: A low, broad dune occupies the center of this 800x450 m (0.5x0.28 mi) scene, blown by a dominant wind towards the lower left. The slip face on the lee side has several small avalanches, formed as ...

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 ...

When the martian surface is eroded, pretty things emerge

A Piece of Mars: Just like at Earth's Grand Canyon, erosion on Mars has created some really beautiful landscapes. This 480x270 m (0.3x0.17 mi) scene shows rugged terrain that was once buried in sediment. Does the texture here represent the ...

Where we have been

A Piece of Mars: This 0.98x0.54 km (0.61x0.34 mi) scene shows ancient windblown bedforms (maybe dunes) that have been partially eroded by the wind. The wind has left behind ghostly stripes: these are remnants of where these things once were, ...

Dune cannibals II

A Piece of Mars: This 0.96x0.54 km (0.60x0.34 mi) scene shows two sets of bedforms (dunes), each aligned in different directions. The more closely-spaced set has sharper crests, and it's superposed on top of (and it is therefore younger than) ...

Wind stripes

A piece of Mars: Yes, I post a lot of pictures of martian dunes with striped patterns. They're all distinct and beautiful. So here's another one, 480x270 m (0.3x0.17 mi) in size. These beasts moved from right to left across ...