January 12, 2017

Tortoise and hare

A Piece of Mars: There’s a lot of evidence for both fast and slow movement in this 480×270 m (0.3×0.17 mi) scene. The tortoise: The rippled surface at the top is high ground: the top of a dune. Wind pushes […]
January 3, 2017

Crater ejecta on old ripples

A Piece of Mars: Mars rarely does anything without drama. Long ago in this 0.96×0.54 km (0.6×0.34 mi) scene, large ripples formed and then, presumably, lithified (turned into rock). Some time after that, an impact formed the crater in the […]
December 26, 2016

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 […]
December 19, 2016

The trail of a dune

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 […]
December 12, 2016

Them that make ripples and them that don’t

A Piece of Mars: Higher ground is to the left. You’re seeing a tan layer sandwiched between two gray layers in this 0.96×0.54 km (0.6×0.34 mi) scene. Large ripples have accumulated in the lowest area to the right, which is […]
December 5, 2016

Martian spiders

A Piece of Mars: Martian spiders, or araneiforms, are geological structures found at high latitudes on Mars. The dark splotch with branching arms in this 0.48×0.27 km (0.3×0.17 mi) scene is a good example. They form in the springtime, when […]
November 28, 2016

Grainfall

A Piece of Mars: The dunes climbing over a rocky surface in this 0.96×0.54 km (0.6×0.34 mi) scene are mostly yellow because they’re covered (and therefore kept immobile) by dust. The crest of one dune, though, shows recent activity: dark […]
November 21, 2016

Bedforms on crater rims

A Piece of Mars: Dunes and ripples most commonly form in topographic lows. But not in this 0.96×0.54 km (0.6×0.34 mi) scene. Here, and in other places on Mars, these bedforms (called TARs) form on plains, and sometimes appear to […]
November 14, 2016

Shadows behind boulders

A Piece of Mars: Bright material (either dust or sand) has accumulated in the lee of wagon- to car-sized boulders in this 0.96×0.54 km (0.6×0.34 mi) scene. It’s perhaps something like the Rocknest sand shadow that Curiosity visited a few […]