[The KG9 Kid]

Wind does this when the playa is wet and muddy from torrential rains.

[IllumiNaughtyByNature]

Ah, mud and rain would better explain it then freezing temps (see above post)except that DV never average more than .42 in. of rain.

This is interesting. I wonder if this phenomenon is seasonal or all year round?

[ErnBatavia]

Yep...I saw a TV program on this phenomenon; that clay becomes slicker than snot when wet.

[tophat9000]

I saw a show on this where they tested various things in a lab recreation of this environment

The combo they found to get this "racetrack rock" effect was a light thin layer of morning ice/frost on the ground and rain water making a very very slick surface ... after that all it took very little wind to make multiple rocks slide along in a common direction at the same time