Unsettling Quick Sand

The standard Hollywood “quick sand” is plain water with a layer of vermiculite floating on top. It crops up so often in movies and it’s always one of the hallmarks of a truly bad film – what director has to reach for such a hackneyed plot device, anyway?

However, quick sand is real – it’s just fairly rare and occurs in specific conditions. This is a really amazing video of some tourists (with a competent guide) exploring quick sand near Mont Saint Michel in Normandy. There’s a lot of tidal action there, and that means sand gets saturated and mixed with water as the tide is going out, which gives a brief window in which the sand gets … weird: [The action starts around 0:48]

Isn’t that nuts? Sand is supposed to be solid.


  1. brucegee1962 says

    Wasn’t it one of the recent Star Wars movies where characters sank into quicksand, said a tearful farewell to one another, then fell through the sand into an underground tunnel? I vaguely feel as if I’ve seen that in other movies as well. No indication of why the sand doesn’t just fall right through. Talk about cheap suspense!

  2. Ice Swimmer says

    I wonder if the shear thinning property is used for pumping sand-water suspensions?

    Pulp fiber slurry is also shear-thinning and medium consistency pulp slurry (8-12 % chemical pulp in water) should be hard enough to stand on, but by fluidizing it it can be pumped with a special centrifugal pump (with air evacuation from middle of the impeller and a specially designed impeller, which features a long screw-like part for the fluidization). The invention of the MC pump led to significant reductions in water consumption in pulp mills because the pulp slurry didn’t have to be diluted to low consistency (1 – 2 %) for pumping.

    One of the inventors later became the Professor of Pulping Technology in Helsinki University of Technology despite only having a M.Sc., but he is also one of the heirs of a family that owned a big company that manufactured process equipment for paper and pulp mills. He was a good and engaging lecturer anyway.

  3. StonedRanger says

    Mostly interesting, but couldnt listen to four minutes of wind noise. We have a river in Oregon called the Sandy river. It too has areas where there is quicksand. I stepped in one and sank to my knees, it scared the piss out of me because it happened so quickly.

  4. kestrel says

    Wow that’s pretty wild. I’ve never seen quick sand before, I had no idea it was like that.

  5. lochaber says

    I’m guessing that’s a pretty similar process that leads to liquefaction of unconsolidated sediment in some areas during earthquakes. pretty cool demonstration though.

  6. says

    The liquefaction videos from Tokyo in 2011 show how precarious is city construction on “reclaimed land”. Nature is going to reclaim it from us eventually.

  7. says

    The liquefaction videos from Tokyo in 2011 show how precarious is city construction on “reclaimed land”. Nature is going to reclaim it from us eventually.

    Yeah, that’s really a scary thing.

    Out here in rural Pennsylvania, it’s not unusual that someone’s house vanishes into a collapsed coal mine. None of that stuff is documented, anywhere, because the former mining companies are all out of business and moved on, and they never wanted people to know where the mines are in order to keep them out. But every one of them is a possible collapse. Eventually some family will be wiped out and everyone will run around wringing their hands going, “who’d a thought!?”

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