Tag Archives: aeolian

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, ...

Shades and textures

A Piece of Mars: This 480x270 m (0.3x0.17 mi) scene shows the contact between two very different terrains. On the left is a bright surface with polygonal cracks (characteristic of periglacial terrain - this is at a high latitude). On ...

Eroded dune

A Piece of Mars: Barchan dunes on Mars have a characteristic crescent shape, with a steep slope ("slip face") on the inside of the sharpest curve (see examples like this, this, these, or this). This image (873x491 m, or 0.54x0.31 ...

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 ...

Erosional remnants

A Piece of Mars: The erosionally-streamlined bright areas are on high ground. They are remnants of a vast dusty mantle that once covered this whole area - the rest of it has been blown away. The surrounding regions (check out ...

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 ...

Dunes not in the global dune database

A Piece of Mars: Ten years ago I participated in a global survey of martian dunes. But we missed a few dune fields, like these beauties. They're small, low, and in rugged terrain, which made them difficult to spot in ...

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, ...

How to hide geology on Mars

A Piece of Mars: Three things are trying to hide in this 0.96x0.48 km (0.6x0.3 mi) scene. 1) Craters are slowly being both scoured and buried by migrating sand, 2) the sand itself is hiding in the lee of crater ...

New craters and wind

A Piece of Mars: The two small dark craters (2.25-2.4 m, or 7.4-7.8 ft across) are brand new, having appeared in CTX images sometime between May 2007 and April 2008. They punched through a layer of bright dust and threw ...