A Terrifying River Of Flowing Rocks

February 26, 2018

This is a video from New Zealand of a granular flow of rocks pouring down the side of a hill near the Rakaia River in Canterbury. What the hell is a granular flow? Let me copy/paste that for you while I down a bottle of DayQuil because somebody got me sick again. I blame the hunk at the gym who was using the eighty pound dumbbells before me. "Eighty?" Ten.

This is a magnificent example of a granular flow. Whilst they appear to be very exotic, granular flows are quite common and have been well-described in the literature. In essence the pebbles behave as particles, allowing behaviour that is akin to that of a fluid. Of course the density of the fluid is somewhat higher than that of a more familiar liquid, such as water, and the particles are many times larger, but the river of rock is still able to generate the sorts of flow structures that we see in water...I suspect that this one comprises particles that are of a comparatively even size--Simon Cox from GNS suggested to me that the material is probably greywacke. It may be that this uniformity lies behind the unusual characteristics of this flow.

Crazy, right? That is not a river I would want to skinny dip in -- those rocks look like they could really tear a pecker up. Now fishing, fishing is another story. What kind of fish do you think you could catch in there anyways? "Rockfish." Wow, you really didn't try too hard, did you?

Keep going for the video.

Thanks to SN, who wants to know if it's possible to skip a rock across a river of rocks.

  • dougfunnay

    Ive never gone tubing....and ive never wanted to go tubing...... until now

  • GeneralDisorder

    You're gonna want to wear some kevlar or steel or iron or something. Unless you really hate your skin where it is.

  • Kaizer Chief

    Ah, the correct use of the word "comprise". Brought a little tear of joy to my eye.

  • Meh

    So where do the rocks come from? Seems like this shouldn't run too long.

  • Doog

    Death Mountain of course.

  • Nicholas Conrad

    Think this is when a troll over does it on coffee.

  • The_Wretched

    "So we shall flow a river forth to Thee And teeming with souls shall it ever be."

  • TheQiwiMan

    "Keep going for the video." - was obviously meant in the most abstract terms. Like, "Don't give up, beloved Geekologie fans. Keep going and some day you'll find the video!"

  • TheQiwiMan

    Or maybe GW just meant "Read Qiwi's comment, he'll hook ya up!"


  • Doog

    First, thanks for the video.

    Second, this is so much more terrifying in video form.

  • Kaizer Chief

    Funnily enough, I saw a comment of yours on YouTube the other day! I think it was on the Today I Found Out channel... Small world, innit...

  • TheQiwiMan


  • Kaizer Chief
  • TheQiwiMan
  • Ollie Williams

    "Keep going for the video"

    "Just kidding. Go fuck yourself." - GW, probably.

  • TheQiwiMan

    Hey, he's sick, cut him some slack. ;-)

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