Is it an old fossil barchan dune?

A Piece of Mars: There are many barchans on Mars, those lovely isolated crescent-shaped dunes. In a few places there are what looks like ancient preserved barchans, now lithified. The mound in the center of this 0.96×0.54 km (0.6×0.33 mi) scene shows what may be an example of a fossil barchan. If so, then this

Windblown or not? Probably…

A Piece of Mars: This 0.95×0.95 km (0.59×0.59 mi) scene shows an eroding surface punctured by some old craters. Long, thin lines seem to form in the wake of many brighter knobs. Are those thin lines windblown in origin? They look like erosional features – things that are left behind when other stuff erodes away

Is it windblown or not?

A Piece of Mars: This 480×270 m (0.30×0.17 mi) scene shows what are being called “ridges”. Were these ridges once dunes that have now been stabilized and eroded? They have some dune-like characteristics: nearly parallel crests, one slope is steeper than the other, that steep slope seems to have exposed layers, and sometimes the crests

Is it windblown or not?

A Piece of Mars: This scene is 0.96×0.54 km (0.60×0.34 mi) across. There’s an old river valley running across it. The walls of the valley have been eroded and there’s a washboard pattern with a wavelength of ~6m (20 ft). When I first saw this image I thought it was exposed, tilted layers, but a

Windblown or not?

A piece of Mars: The surface in this 960×540 m (0.6×0.34 mi) scene has a distinct fabric to it that runs from the upper left to lower right. Are these old lithified dunes? And what makes the tiny filamentary lines that run from upper right to lower left, are those ripples? I’m not convinced either