Tag Archives: ripples

Tortoise and hare

A Piece of Mars: There's a lot of evidence for both fast and slow movement in this 480x270 m (0.3x0.17 mi) scene. The tortoise: The rippled surface at the top is high ground: the top of a dune. Wind pushes ...

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 ...

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 0.96x0.54 km (0.6x0.34 mi) scene. Large ripples have accumulated in the lowest area to the right, which is ...

Windblown: ancient and recent

A Piece of Mars: HiRISE is celebrating 10 years of success by showcasing its first high resolution image, taken back in 2006. Here is a portion of it, shown at 1/4 the full resolution (the scene is 2.5x2.5 km across). ...

Light and dark

A Piece of Mars: This 0.96x0.54 km (0.6x0.34 mi) late winter scene is a study in contrast. The dark top half is uniformly rippled. This is the shady surface of the main windward side of one of Mars' biggest dunes, ...

Where does the windblown stuff come from?

A Piece of Mars: How far do windblown materials move on Mars? This scene (0.9x1.2 km, 0.56x0.75 mi) shows a bright layer of bedrock (top right) that is eroding, exposing a darker, bluish rock (bottom left). Ripples 5-20 m wide ...

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 ...

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, ...

Landslides unlike any on Earth

A Piece of Mars: Click on this 0.96x0.54 km (0.6x0.33 mi) scene to see it in detail. Many thin, narrow landslides have formed on these dust-coated hills. As far as I'm aware, there's nothing like this on Earth. Inside the ...