At TAM 2013 last month, I presented a news article (courtesy of The Weather Channel’s website) which told of a long-standing mystery that had “finally” been solved. However, it appears I presented an incomplete report. Here is how my report basically went, as told at TAM.
Known as The Sailing Stones of Death Valley, these rocks appear to be moving across the ground all by themselves, and scientists do not know how this is happening. And no one would know that the rocks are moving at all, if it weren’t for the trails they leave. Some of these stones weigh as much as 700 hundreds of pounds, and they are leaving trails thousands of feet long.
These sailing stones were first reported in 1915 (so that’s almost 100 years ago), and they have been investigated ever since by geologists from UCLA and the US Geological Survey.The problem is that the researches have yet to witness the rocks in motion.
Previous hypothesis included:
Rainstorms – which cause flash flooding followed by intense winds (which can reach 70 mph) – but this can not account for the heaviest of the stones moving. They are just too heavy.
Gravity – is there are slight slope, so perhaps they are very slowly sliding downhill at a glacial pace. However this can not account for how some of the stones move uphill – because at the southern end of the Playa (a dried up lake bed in the valley) this is where some of the rocks begin their journey and the southern end is a few centimeters lower than the north end.
So what’s going on here? Are the supernatural forces at work? Is this an elaborate hoax of some kind? Are ET’s messing with our heads?
Well, according to the article, the mystery seems to have finally been solved.
Enter Ralph Lorenz (not Ralph Lauren) Johns Hopkins University. He is a planetary scientist, and he had been working on a project setting up weather stations in Death Valley.
He noticed that the paths of the stones put them on a “collision course” with one another, but instead of a collision, one of the stones seemed to somehow deflect the other stone’s trajectory just slightly enough so that they never actually touched.
And he remembered reading something similar to this occurring in the Arctic, with Arctic boulders. The weather data Lorenz had collected told him that the desert got cold enough for something similar to be going on in Death Valley. So he decided to try and replicate the effect, and he describes it as such:
“I took a small rock, and put it in a piece of Tupperware, and filled it with water so there was an inch of water with a bit of the rock sticking out. I put it in the freezer, and that then gave me a slab of ice with a rock sticking out of it.”
By placing the ice-bound rock in a large tray of water with sand at the bottom, all he had to do was gently blow on the rock to get it to move across the water and viola – you get a rock drawing an impression in the sand.
Lorenz’s research team calculated that under certain winter conditions in Death Valley, enough water and ice could form to float the rocks across the muddy bottom of Racetrack Playa in a light breeze, leaving a trail in the mud as the rocks moved.
This is basically what I presented at TAM, however, soon afterwards, I was made aware that Brian Dunning of the Skeptoid podcast had actually tackled this subject himself back in 2006, and he came across another explanation, with video footage to back up his report.
As Brian explains:
“Solid ice, moving with the surface of the lake and with the inertia of a whole surrounding ice sheet, would have no trouble pushing a rock along the slick muddy floor. Certainly a lot more horsepower than wind alone, as has been proposed. The wind was gusty and moved around some, and since the surface is not perfectly flat and with rocks and various obstructions, the water didn’t flow straight; rather it swapped around as it moved generally forward. Ice sheets driven by the water would move in the same way, accounting for the turns and curves found in many of the rock trails.”
So credit for Brian for an additional, highly plausible explanation. Unfortunately it was not covered by The Weather Channel’s article, and uncovered by the other 4 articles I looked at in support of my TAM news item presentation. Otherwise, I definitely would not have overlooked Brian’s contributions to helping solve this “mystery.”