Where is the zebra? Options

[SigurRosFan]

- http://www.msss.com/mars_images/moc/2006/05/12/

[Guest_Richard Trigaux_*]

Very interesting image, SigurRosFan.

A bit puzzling, because of bottom lighting. I managed to see it correctly with head tilted horizontally to the right. The left part of the image appears lower, and the slope in front of us.


What is interesting is th fact that the dark streaks don't stop at the borrom on the slope, but somewhat continue on the flat bottom. This is an evidence that it is a dynamic process, occuring at high speed, not a slow crawling process.

On some parts of the bottom at the foot of the slope, the ground shapes appear slightly obliterated. This is an evidence that these dust avalanches were numerous in the past, but that they carry little dust at a time. This conforts the theory as what they are formed by falling dust accumulating on the ground.

At last, there are many streaks of roughly the same age here. Perhaps a quake triggered them all in the same time.

Acheron fossae is a puzzling small zone of highly fractured terrain showing many horsts and grabens*, north of Olympus mons. It seems recent, and perhaps still active. It is part of the overall fault belt around Tharsis plateau.

*horsts and grabens: parallel parts of terrains, uplifted or subsided, between parallel faults.