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Initial Impressions
Mud Tracks
Observations and Theories
In Conclusion
Initial Impressions
(This commentary is from our trip to Death Valley on 08/23/2003)
Well, we finally made it out to Racetrack Playa in Death Valley to see the mysterious moving rocks. Even though I've been reading about it for weeks, actually being there and seeing it is a whole different experience. The hugeness and the flatness of the playa are breath taking.
First of all - The rocks do indeed slide across the ground, and it's the wind blowing through the canyon that makes them move. No, we didn't get to see them moving, but it was pretty obvious that's what was happening. We stopped at Ubehebe Crater before heading up the 27 mile road and the wind was blowing so hard we almost got blown over. The wind was a bit less at Racetrack, but still strong.
Even though they'd had flash flooding a few days before, the playa was completely dry by the time we got there. We could see that someone had been walking out to look at the sliding stones while it was still muddy though. Along with the tracks you could see several sets of foot prints that looked like they were made at nearly the same time.. I would love to talk to these people. Did they see the rocks move? How slippery was the surface? Was there standing water or just mud?
One interesting thing that the tracks indicate is that there is a hard layer that sits under about an inch of mud. We looked at other mud holes left by the recent storm in other sections of the park, and tracks there sunk in various depths, but some went down 6 inches or more. All of the Racetrack tracks were an even depth. And even though they were obviously made in soupy mud, none of them sunk in further than an inch. This helps explain why the stones don't get mired in the mud.
We could also tell that the stones hadn't been encased in an "ice raft". The tracks made when the playa was dried had distinct piles of mud that didn't look like they'd formed under water or ice. That is, it seemed clear that the rocks moved while there was no standing water on the playa.
One of the other odd things we saw were tracks made by clumps of mud. We could see where a clump (or typically several clumps) about 4-5 inches wide and 1-2 inches front to back would break loose and scoot across making a track that looked just like the rock's tracks. These seemed to usually occur in a sets of 4-5 with a very regular spacing. I found these very odd. I suspect dust devils or some other cyclic force caused them. I also wonder why I've never read about these in any of the literature.
Mud Tracks
Besides the sliding stones, in several places we saw tracks that had been made by clumps of mud. At first we thought people had come out and removed the rocks after the tracks were made, but we saw more and more examples it became apparent the clumps of mud were breaking loose and sliding through the mud.
I hadn't read about anything like this is any of the other accounts. Is this normal?
The tracks were shorter and not as deep. They were also much less regular and distinct. The weirdest thing is that about half the "mud clump tracks" appeared in a series. So we'd see 4-5 tracks in parallel with very regular spacing.
In at least three places I saw the following:
4-5 parallel tracks with clumps of mud at the terminus. A few feet away would be a haphazard group of tracks with random direction and size, which crossed over each other making a big mess. Almost like someone had taken a big broom and swiped it back and forth randomly. But of course there were no footprints.
I was really struck by the regularity of all this. The only cause I can think of would be something like a dust devil. But I have no idea how it would cause the tracks we saw which were in a parallel series.
Observations and Theories
One of the first things I noticed was that most of the rocks hadn't moved at all after the last storm, while others had made deep tracks up to 100 feet long. Obviously there is a very specific set of wind and rock geometry that will set the rocks moving. Strangely, the moisture level in the mud didn't seem to be a factor. We found some tracks where the mud had flowed part way back into the track, and others where the mud had obviously been less soupy.
Another thing I'd wondered about, after reading through the previous research was where the rocks ultimately went. Did they slide all the way across? If rocks are steadily falling off the cliffs to the south, and a certain percentage are making it onto the playa, they must pile up somewhere.
After visiting I still have no idea about that. Many of the tracks we saw were heading back towards the cliff. And the rocks definitely thin out as you get farther from the cliff. So I don't think they make it all the way across. It seems like after hundreds of years you'd get a big pile up somewhere in the middle. But we didn't see anything like that.
I suppose it's possible that people come out and steal the rocks. But that wouldn't account for the hundreds of years before people showed up.
We also saw several rocks that didn't come from the black cliffs to the south. While most of the rocks were black, squared off chunks, several were more like tan sandstone and showed weathering similar to what you'd see in river stones. Are people adding their own rocks to the playa?
Unfortunately we got the playa very late and we only had about an hour to explore before the sun went behind the western mountain. The playa is so huge, and the rocks are so spread out that you could easily spend half a day just getting to most of them and taking photos. I was rushing around like crazy, but I felt I'd barely gotten a look at the place. We'll need to head back again. Hopefully with more time to investigate. I really wanted to take GPS reading from the stones, but there wasn't time. Ditto for panoramas.
One other observation - Once you stand on the edge of the playa you realize why no one has seen the rocks move: They are about 1/3 of a mile from the edge. You literally can't see them. If one of them was moving at 5-10 MPH you'd never be able to tell from "shore". And even once you're out there you still have a huge distance between stones. If one was moving you'd have to slog through 100 yards of muck to get near it.
In Conclusion
I still have no idea what to make of Death Valley's Racetrack. Here you have a place where rocks slide across the ground all by themselves. And they only move when no one is there to see it. And scientists have been unable to come up with a better explanation than, "When it's muddy and windy, the rocks move. Sometimes."
It makes it even more magical that these rocks are a few miles from the deepest hole in the western hemisphere, and a huge crater caused by a massive steam explosion, and the hottest place you'll ever be, and is a favorite for both scientists *and* new age loonies.
I want to complain about how crappy the road is, but on the other hand I think I like it better that way. The road is bad. Not so much because it's a 4WD road (it really isn't), but more because of the horrendous washboards you go over for 27 miles. I've read several accounts of people who went up there and trashed their car in one way or another. The bat snuggler had to take hers to the shop after we went.
But I think I'd rather it was hard to get up there. With people so eager to mess with the place - taking rocks, adding rocks, driving over tracks - I'd rather the park service tried to discourage people who weren't determined.
But I think I'd rather it was hard to get up there. With people so eager to mess with the place - taking rocks, adding rocks, driving over tracks - I'd rather the park service tried to discourage people who weren't determined.
As absolutely awful as Death Valley is it's also very magical. The sweetie bat mentioned that it was about as close as you would ever come to being on another planet, and I suppose that's accurate. Unfortunately most of the visitors seem to have the attitude that the park was put there for them to screw with. They don't seem to understand that the main point of the park is geology - Natural processes that took millions of years to create something magical. If you take things, or move things around, or drive all over something just because it's pristine, you break something that can never be fixed.
Other Racetrack Playa Sites
A great site with tons of background on the magic rocks. No photos and light on science, but a very good introduction to the Racetrack.
A long article with lots of detail and a very good breakdown of the various theories. Excellent reading.
This is a reprint of the Paula Messina and Phil Stoffer article in California Geology Magazine. It is best and most timely online article I've found.
Lots of very good recent pictures of Racetrack Playa (very high bandwidth!!!).
One of the best pages for hard science. Lots of pictures, history and charts.
Excellent site with tons of photos, hard data, and a great Bibliography. Be sure to click on the "Go on to next page" icon at the bottom.
Lots of great hi-res pictures.
More photos and charts. Very nice.
Some nice background. A few items I haven't read anywhere else.
"The Sliding Rocks of Racetrack Playa, Death Valley National Park, California: Physical and Spatial Influences on Surface Processes"
Chapter 2 of Paula Messina's dissertation (PDF), which is probably the best summation of the Racetrack research prior to her studies.
Lots of very good photos.
The US Geological Survey page on the Racetrack. Short, but good technical detail.
Another detailed article
Hardly any data, but the only place I've found the "Tsunami Theory" mentioned.
This is the National Park Service page on the playa. Not much detail though. Very brief.
One picture and an eye witness acount.
More pictures and accounts.
An eye witness acount.
Not Racetrack related, but a great resource for those interested in the science of the playa surface.
A photo and short article.
More photos and brief comments.
A few pictures and general background.
A page with info about the rather nasty road leading to the playa. Very handy if you're planning on driving out there.
This is a Park Service web site for Death Valley.
Lots of silliness and more photos.
About Death Valley in general, but it has some great photos of the rocks.
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