crossbedding
April 23, 2018
The wind on Mars is an artist, or at least it tries really hard to be one. It flutters up and down mountains, winding along valleys, dragging its wings in the sand and building up really amazing structures that could […]
March 19, 2018
A few weeks ago I wrote about dunes leaving behind trails near the north pole of Mars. They do this in a few other places as well, but it’s not very common. Below is a rare example, this time on […]
March 1, 2018
There’s so much going on in this 0.75×0.75 km (0.47×0.47 mi) image. You’re looking at a broad dune migrating toward the upper right. It’s early summer, but this is close enough to the north pole that some winter ice lingers […]
February 5, 2018
The busy, busy wind has moved a lot of things to make this 0.6×0.85 km (0.37×0.53 mi) landscape. First it built a big dark dune, covering it and the surrounding surface with ripples. Then it dumped a bunch of bright […]
January 2, 2018
A Piece of Mars: The dunes (or maybe they’re ripples) in this valley appear to be fuzzy (the view is 625×775 m, 0.39×0.48 mi). They’re not really fuzzy, but it’s not actually clear what’s going on. They seem to have […]
November 27, 2017
A Piece of Mars: The rippled darker patch in this 600×600 m (0.37×0.37 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 […]
July 25, 2017
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 […]
February 27, 2017
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 […]
December 19, 2016
A Piece of Mars: A low, broad dune occupies the center of this 800×450 m (0.5×0.28 mi) scene, blown by a dominant wind towards the lower left. The slip face on the lee side has several small avalanches, formed as […]