Chris Peterson wrote:There's a subtle axis of structure in this image running from top right to lower left. It is seen in the asymmetrical filling of the craters, and in fine lines most visible in the lower left. I assume this is a consequence of long term prevailing winds. I'm having a hard time figuring out what the illumination angle is here; I suppose that could impact the appearance of this structure.
If you look at the top crater, the sand is striated in a near perpendicular angle to the others. Would prevailing winds create such a difference? Maybe the mechanism is different? Maybe how the sand slides into the crater down the sides?
I am thinking "standing sand", and the way it has "settled"... click on the image and look at the large image in magnification. Look at the "webbing" in the middle crater. Reminds me of Ice that has stood for some time, and has settled out. The striations get closer, the further to the up and right of the crater... The top down view, and light angle may make it a little deceptive too. See how it "rumples" near the walls of the crater.
Maybe influence in the structure beneath the sand on the crater floors?
There is very little striation on the surface outside the craters. Hard to tell which why the wind had blown, has it blown "down" the scene, or "across"? There is a crater in the upper middle of the RIGHT EDGE, where there appears to be sand that has spilled into a more shallow crater, and there appears to be a more fluid-like flow. But little or no striation, unless influenced by the surface. The build up in these craters APPEARS to be built up in the lower RIGHT of the craters...a totally different direction from the large craters... This appears to hold true for the rest of the area out side of the craters. I think the deeper sand build up, has "settled". Not blown. Bunching up against "structure" on the crater floors, and getting deeper, the differences being magnified.
And... just a thought....Water waves leave ripples. And when water drains, leaves, or evaporates, those ripples remain...