dunes

November 12, 2012

Big dunes and little dunes

A Piece of Mars: A large dune (on the right, bluish) rests on a surface covered in much smaller dunes or ripples (on the left, cream). This is part of my favorite dune field on Mars. Can you spot the […]
August 24, 2012

The dunes near Curiosity

A piece of Gale crater, Mars: Here are some of the large, dark dunes not far from where Curiosity has landed. They’re pretty big monsters, 200-300 meters across. Their shape indicates they’ve been formed from two different wind directions: one […]
August 3, 2012

A beautiful tangle

A piece of Mars: Compare this with my post five days ago and you might think the scenes are similar. In fact they’re not. In the previous case sedimentary layers were carved out by the wind, leaving behind swirly patterns […]
July 30, 2012

Double trouble

A piece of Mars: Bright dunes once marched through the depression created by a double impact. How can you tell the dunes are no longer moving? Because one of them has its own little crater sitting on it. A mobile […]
July 14, 2012

Barely a dune

A piece of Mars: What makes a dune different from a random pile of sand? Usually the requirement is that it has a “slipface”, a steep avalanching slope. The central dune in the image here has a small one, making […]
July 11, 2012

Wrapping around

A piece of Mars: Dunes near the north pole of Mars form in a very cold environment. Winter ice continually tries to stop them in their tracks, which makes for unusually rounded dunes like these. (HiRISE ESP_027451_2635)
July 9, 2012

Dunes all gone

A piece of Mars: Way up in the cold northern plains of Mars, some of the dunes are being blown away slowly by the wind. Here are some that are barely there yet — dark patches of sand in the […]
June 20, 2012

Dune bones

A piece of Mars: The thin stripes within stripes are the bones of dunes. You’re seeing old dunes that have had their tops eroded away so you’re seeing into their insides, as if you were dissecting them in a biology […]
June 19, 2012

The edge of the ice

A piece of Mars: This is the edge of the northern polar cap on Mars. At the top is the bright icy surface, which is abruptly cut by a cliff. The wall of the cliff shows many layers of different […]