Sliding Rocks Bemuse Scientists 433
An anonymous reader writes "Scientists can't figure out why these rocks — weighing up to several hundred pounds each — slide across a dry lake bed. The leading theory proposes that wind moves the rocks after a rain when the lake bed consists of soft and very slippery mud.
Mark Newman Poster (Score:5, Informative)
Re:Mark Newman Poster (Score:5, Informative)
Its not that hard to figure out! (Score:2, Informative)
Everything must be ruled in or out, but... (Score:3, Informative)
I've camped a few times at Texas Spring campground in Death Valley. Nice place in the right times of the year. One year, however, the wind blew all night at about 40 knots. Nearly took me and my tent away. There are sand dunes to the north of the valley, too. I expect the winds there are more than up to the task of pushing around rocks on moist clay. Perhaps most enigmatic is the question, 'Why don't these larger rocks sink into the mud?' Though with strong enough winds, I imagine they could get a move on again.
Re:Amazing how no-one bothers to actually CHECK. (Score:5, Informative)
And as to the foolishly simple explanation, H.L. Mekcken is quoted to have said, "Every complex problem has a solution that is simple, direct, plausible, and wrong".
Re:Begs the question (Score:2, Informative)
Re:Mark Newman Poster (Score:3, Informative)
Indeed.
When my heavy beer glass gets a tiny bit of water between it and the hard table, it starts sliding around all by itself, with no wind at all. I can imagine that these stones slide similarly.
Re:It's a Horta! (Score:3, Informative)
* The rocks don't move very often -- typically once every two or three years.
* Cheap webcams have only been around for a few years, and I don't know if there have been any movement episodes during this time.
* It's an incredibly hostile environment for electronic equipment: surface temperatures of 150+ degrees F during summer days, temperatures below zero F during winter nights, violent rainstorms, and intense direct sunlight.
* There is no electricity. There is no internet service. There is no wireless phone service. During the rainstorms when the rocks are expected to be moving, there is no satellite service.
* There's the ever-present risk of theft.
Re:Begs the question (Score:3, Informative)
http://wsu.edu/~brians/errors/begs.html [wsu.edu]
Raises the question != Begs the question.
Re:It's a Horta! (Score:4, Informative)
From a dependable source [pbs.org]:
If you've never been to Death Valley in the summer, you should give it a try. If you're from a mild climate, I suggest March instead; the regular 90 degree temperatures before April has shown it's face will give you a little idea of the radical heat that this region experiences.
*The Racetrack and Badwater are both below sea level, so you'd need to get up to at least 240f to boil water.
Re:Mark Newman Poster (Score:1, Informative)
Re:Mark Newman Poster (Score:3, Informative)
When the glass is put down, if the water seal forms before the glass has fully contacted the surface, the air pressure will lift the glass as it evens out the pressure on the air cushion. This will cause it to be riding on an air bearing, and slide very easily.
Usually it will only go until the water seal is broken, releasing the air pressure that forms the cushion. If the surface is moist enough, the cohesive water can renew the seal as it glides.
If you try this with a very flat, nearly level surface and a glass with a concave bottom you can get good results.
Hot liquids can actually expand the air under them and suddenly lift up and slide.