That really is a trip … it does make me a little sad, though, that I didn’t go down to Black Rock City this year for the Burning Man festival. Man dad is a geophysicist and he really enjoys the ‘racing rocks’ phenomenon because geological time is usually so slow!

Wow.. it’s odd that it washes over some rocks, completely ignoring them. I guess it’s a matter of which area of water is the most dense. Forwarding this one to a few friends :)

MG, all bodies of water and sections of those bodies of water will have the same density…I think it would depend on current or the size of the rocks, possibly how deep they are embedded?

It is also interesting to note that the crinkled surface of the mud remains relatively unchanged. I am guessing that the mud is frozen or baked hard so that the water flow doesn’t change it but a rock dragging across the surface would. Without that video, one would have to assume some hippies from Burning Mans wondered over in the night and did the rearranging.

I wonder if the clay surface of the dry lake bed contains the mineral called Kaolin? Kaolinite is a clay.It is a soft, earthy, usually white mineral (dioctahedral phyllosilicate clay), produced by the chemical weathering of aluminium silicate minerals like feldspar. In many parts of the world, it is colored pink-orange-red by iron oxide, giving it a distinct rust hue.It is widely used as a replacement for talc.It is also used as a lubricant.It is what gives glossy paper it slick shiny appearance.
If kaolinite is leeching out of the clay when it is wet or submerged with water the surface would become very slick!

I just watched the video but I never actually saw a rock moving just the water flowing.

water seeping upward through the ground freezes on the surface in cold times. I have previously observed these long icicles which appear to grow from the ground and carry topsoil. The frozen crystals should have sufficient power to move the rock very slightly in the upward direction. When the sun shines again, it causes the ice to melt where there is no shadow, causing the rock to sag in that direction. Upon sagging “forward” the rest of the ice will melt or alternatively the ice will grow under it again. This causes an inching effect, the reason for the paths is that the ice will generally grow everywhere, however the rock has a compaction effect of the ground it is situated on. Irregular rocks have irregular shadows and hence the differential preference in direction, direction can change depending on the time of year and the position of the sun relative to the rock, there is also the possibility of rock rotation, based on the same principle. Does anyone agree?

:-) Knowing how the trick is done doesn’t make it any less magical

What I think needs to be added to the explanation is the effect of pore pressure at the interface between the bottom of the stone and the wet mud surface. Pore pressure is a resisting upward force generated by a film of water that occurs around and between mud particles and confined by the block of rock above it. Since water is virtually incompressible, the object is able to move laterally in response to a temporary current produced by the advancing edge of the temporary lake. But the pore pressure “buoys” up the rock, and it can slide on extremely low slopes, such as that of the playa (normally an intermittently wet, surface of deposition in a dry climate environment.

It is sort of analogous to hydroplaning tires on wet pavement. The tires are not in contact with the pavement because of the film of water between the tires and the pavement. Water cannot be compressed, so any confined water in the tread builds up pore pressure, and floats the car (or the rock). Sometimes you can see a water glass with a wet bottom slide in funny directions on a table.

Try and push an irregularly shaped rock in a straight line with a broom, stick, board, car, or even your hand. Hard isn’t it!

Also, try pulling an irregularly shaped rock in a straight line by tying a string to it. Doesn’t track in a straight line does it?

Unless you have a hockey puck, a blemish-free sliding surface, and a perfectly uniform sheet of ice being blown by a perfectly straight wind, the track that is going to be left when all is said and done will not be straight.

Why exactly is it surprising that non-linear tracks are left by the irregularyl shaped rocks, which are being pushed by irregularly shaped ice, which is in turn being pushed by irregular wind? Also consider that the sheets of ice will encounter other bigger rocks or surface irregularities creating friction and pivoting of the direction of force.

Experiment: sprinkle a little sand on a frozen pond surface. Put a rock on it. Get a piece of thin plywood and cut it in a random shape. Now put that next to the rock. Stand behind the sheet of plywood. Now push it and see if you can make it track in a straight line.

Now theres a theory that makes sence. As for the rocks in proximity of others that dont move, I think you will find that the non-moving rocks are kept in place because of jaged surfaces facing down, anchoring them, where the moving rocks were likely to have a smooth surface oriented against the surface of the mud. Also if this ice sheet is the force that is pushing these rocks, mabe the jaged surfaces facing up is fractureing the ice rather than letting it push them. At any rate that would answer some of the theorys. What about the large rocks, and how big are the largest rocks with trails behind them? Any as big as say a 5 gallon bucket? or a dish-washer or a similar size? Id think the force to move such a large size would negate the ice-flow theory……..at any rate its an interesting mystery