Who took the rocks?

The Racetrack playa. Rocks tumble on to the playa. From our visit here on the 18th of February, 2010, it appears that this could only happen on the far Southeastern end of the playa. Photos have been taken for decades of the “trails” rocks leave on the flat playa surface when evidently “rafting” across the surface. This could happen when the playa is wet. When wet, the surface is extremely slippery and with a flat slippery surface, it doesn’t push the imagination to envision, rocks skidding across the surface.

I have read that another theory is that the rocks could raft when the surface was frozen and with the aid of strong winds. Of course, with a solid frozen surface, it would seem that the rocks would leave no mud trails. More on the “ice” possibility later.

I read that because the playa is so perfectly flat and so “slippery” when wet, that even an inch of water can be blown to one end of the playa or the other. This again seems plausible but once the winds stopped, it would seem that the wind blown water would once again seek the level and spread back out across the entire surface.

When we arrived at the Racetrack playa, we were the only visitors. So our first stop was to park near the Grandstand (a big dark granite outcropping on the northwest end of the playa. Here we took a few photos and observed the beautiful pattern that the drying mud creates all across the surface of the playa. The park department has dug a deep trench along the western shore of the playa, trying their best to deter the “IDIOTS” who would mar the surface by driving across it. Faint tracks on the playa surface indicated that has been done many times over the years.

Hearing that most of the “moving rocks” and their mud trails could be found at the south end of the playa, that is where we drove. I knew it had rained a lot in the previous weeks and dirt roads within DVNP had been damaged by the resulting alluvial flooding. Still, with temperatures now in the high 70s and low 80s, I didn’t expect to find water in the playa but we did. The last half mile of the southern end of the playa was under several inches of water. Some of the bigger rocks at this end of the playa formed reflecting “islands”, any moving trails they may have made, were now underwater.

The weather was perfect. No wind. Nice sunny day and pleasantly warm. So my wife and I drove back almost to the Grandstand area, and parked our pickup truck. We decide to take cameras and binoculars and circumnavigate the entire DRY portion of the Racetrack playa. I would use my camera telephoto to photograph the “moist” (and presumably muddy and slippery) portion so as not to leave any human tracks on the drying portion of the playa.

Still, just walking the dry section, which covered 3/4 of the playa, took a lot more walking than we thought. It was quite a walk just covering the distance across the width of the playa. But the walk was worth it. Good exercise, fresh air, and we got to observe a number of “mud trails” left by rafting rocks now marooned on the dry portion of the playa.

All of the rafting rock trails we observed showed that the rocks had been blown from the north and traveled south. Since there are no rocky cliffs except at the southeastern corner of the playa, that means that the rocks take “rides” all across the playa, sometimes rafting north and sometimes rafting south (high hills on either side of the playa on the east and west side, would prevent strong winds from blowing across the playa from that direction.

The mud trails read like a book. In observing the rocks, where they sit and how they sit, and their arrival dried mud trail behind them, you can clearly envision their trip. It appears they move quickly when blown across the wet (not icy) flat playa surface, and then “dig in and plow” a mud mound before them as they come to a halt.

The result is a rock sitting on or behind a mud island at the end of a trenched mud travel trail. You can also see by the leading edge of the rock, how the soft wet mud covered part of the rock when it came to a stop.

After walking the entire playa and observing lots of different rafted rocks of all sizes and shapes, we encountered what to me is the real “mystery” of these rocks. Missing rocks!
At the end of about 1/4 of all the dried rock mud trails was the clear sign of that terminal mud island that I describe BUT the rocks were gone! This could only be explained (to my way of thinking), if that a later time, ice formed on the playa, which was just as slippery as the wet mud version, and then the rocks were blown off their mud pedestal and were rafted across the surface leaving no trail behind them. OR

Somebody picks up a few of the rafted rocks and then carries them to the edge of the playa (we saw no rocks on the playa without some sort of “rafting trail”. I didn’t see any signs of ATV tracks (though the soft wide tires of those might leave few, no, or faint tracks - - and I can’t imagine somebody wanting to create a mystery, trying t carry a 20 pound rock a mile, to the playa shore, but they may. So I don’t have the answer, but it was intriguing.

The other mystery we found was a large wet perfectly round mud hole that existed right in the middle of the driest part of the playa. If you didn’t know better, you would assume that a 100 pound round rock had been dropped from the sky from a 1/2 mile up then the rock removed. Then the drop hole filled with water, which had yet to evaporate. I posted a photo in this photo set of that particular “phenomena”. It was the only such sight we saw and again, we walked the entire length and width of the dry portion of the playa.

I have seen photos of the “moving rocks” of the Racetrack playa over many decades. To my knowledge, nobody has yet to see the rocks move (does the wind blow only at night or are the roads to the playa not traveled during severe storms). Seeing the place for ourselves was a real treat.

Wikipedia info I looked up since returning: Racetrack at 3,600’ elevation. 3 miles long and one mile wide. Playa is very flat BUT north end is 1.5 inches higher than southern end. Drying mud forms the rock hard hexagonal tiles 3-4 inches in diameter and an inch deep. Rocks only move once every two to three years and the tracks they leave last three to four years. Nobody has seen or filmed the rocks move. Prevailing winds are from the Southwest. This means the rock trails we observed which had been formed by the rocks rafting north to south, were unusual.

We wanted some sun, blue sky, warm weather and the opportunity to see some of the sights in a national park, that neither of us had visited. We got it all. High 70s in DVNP on the day we spent there.

Starting at the break of day on Thursday the 18th of February, 2010 we visited the following places in Death Valley National Park:
Stovepipe Wells; Mesquite sand dunes; Teakettle Junction; The Racetrack playa; Ubehebe crater; Titus Canyon; Furnace Creek; Borax museum; and the pup fish of Salt Creek (right at dusk).

The Racetrack playa, which we had all to ourselves was the highlight of the visit.

The photographs in this photo set are mostly from the places we visited within DVNP, but there are also some photos of the back road sights we saw on our our way down and back to DVNP.

To read the full account of the route we took, to and from, and more about the places we visited withing Death Valley National Park - - read the narrative that accompanies this photo set. Thanks! OMT