Death Valley Racetrack Mystery Revealed!

[Drew Wiley]

Part 2: then look up the study to see if this part matches. If that playa contains bentonite or a similar hydroscopic clay (probable), what the happens is that if enough moisture is present there (it doesn't have to be a soaking rain), the clay swells shut and essentially waterproofs itself. That means a very thin film will remain on the surface and not soak in. Being thin, it will also easily freeze, but in a different manner than under the rocks. The clay particles themselves are virtually interlocked, just like a tortoise shell. I learned all this selling clay-based waterproofings. So that ice will produce an ephemeral ice-skating rink, which will sublimate and disappear the next dawn. Soaking rains will, on the other hand, soak the playa and become apparent as crack patterns. Not common on the Racetrack; but it can happen once in awhile. So are there any new tweaks to this fifty year old explanation, or just a confirmation of it? A few nails out there might help with the ATV vandalism.

[Struan Gray]

Plos One is a respectable journal. That doesn't mean it's holy writ, but the obvious objections will have been covered.

This study doesn't rule out ice heave as another mechanism, but it seems unlikely to me. The parallel tracks with matching kinks and changes of direction fit perfectly with the idea of several boulders held by the same large ice sheet and being carried along with it. They would be hard to reproduce with an ice mechanism, especially with different size boulders - most freeze-thaw flow patterns also involve size sorting.

The journal article is pay to read (unless you have an institutional subscription), but the figures and captions are available for free. They make the argument pretty clear - and, to my mind, watertight.

[Drew Wiley]

Ice-heave via needle ice is the basic mechanism behind rock glacier, sorted rings and mounds, etc - that is something I've studied quite a bit, and it does not fit
the Racetrack phenomenon at all, other than the probability that needle ice very briefly forms under the rocks, as I already described. Why do I say that? - because of the basically dessicated conditions where that kind of thing is likely to transpire after the water condenses. But it would be a very temporary thing. Frost heaving
requires months, years, centuries to do its thing to any conspicuous degree. As much as I hate the proliferation of drones, it would be one way to systematically
map what those rocks are doing. But I still think the very most probably explanation is that aliens are playing either bocci ball or croquet out there.

[Struan Gray]

Has anyone considered the possibility that the whole playa is moving, and the rocks are standing still?

We have solifluction terraces on our local hills in N.W.Scotland which are probably remnants from the last glacial maximum (it hasn't been cold enough for long enough since). I always find it odd that a hundred year old wood will be designated a pristine nature reserve, but not ten thousand year old soil structures.

[BrianShaw]

Has anyone considered the possibility that the whole playa is moving, and the rocks are standing still?

Good thought. Maybe that's how it really works and the GPS sensors on the rocks were deceived.

[Drew Wiley]

Darn aliens sure have us tricked, don't they? Making the rocks stand still as the earth revolves!

[Kirk Gittings]

Good thought. Maybe that's how it really works and the GPS sensors on the rocks were deceived.

Well duh!

[Drew Wiley]

GPS has it shortcomings, especially when the person reading it is holding it upside down and thinks east is west. .. especially when he think an official trail sign with
an arrow pointing one direction is wrong, and his GPS is correct instead. I won't relate the whole story like I did over on APUG, but it happened two weeks ago. His
friends were waiting at the parking lot, two miles away one direction, and he insisted on going the other way, twelve miles away when he finally reached the wrong
trailhead, with no cell phone reception in that area. The brains behind inventing that device mean very little if the person reading it has no brains of his own!

[Bob Sawin]

Always held hope that it would turn out to be Bigfoot skipping stones...