What Exactly is Quicksand?

Quicksand is a staple hazard of adventure movies, TV shows and video games. Whenever a minor character needs to be killed off quickly, the hero needs someone to rescue, or danger needs to be introduced without calling the villain in, quicksand is there to fulfill the task and swallow an explorer whole. Conveniently, there’s always a pool of pasty goo sitting around somewhere, usually perfectly circular and somewhat hidden from the characters’ view. This shouldn’t come as a shock, but real quicksand isn’t exactly how Hollywood makes it out to be.

Quicksand is what happens when regular old sand or grainy soil gets mixed with water under the right conditions. Normally, sand/soil can support weight on top of it because the friction between the grains helps distribute the load across a large area. If enough water seeps up from an underground source and gets under and around each grain, though, the friction gets compromised and the soil and water become a suspension where the grains are floating around in the water. The ground loses a lot of its ability to support weight, and takes on a consistency somewhat like wet concrete. If you step on it, you’ll start to sink, though not necessarily to your doom.

Despite its frequency in fiction, complete submersion and death in quicksand doesn’t happen in real life. Objects sink only to the level at which their weight is equal to the weight of the displaced sand/water mix, and then the object floats due to its buoyancy. The average person is only going to sink to his or her waist, elbows or armpits, depending on what they’re wearing and carrying. People who die in quicksand don’t die because they sank all the way in, but because they weren’t able to get out quickly enough and were exposed to the elements — low temperatures, incoming tide, etc.

Because quicksand needs underground water to form, riverbanks, beaches, sand washes, alluvial fans, swamps, marshes, and areas with natural springs are the most common spots to find it. It can, and does, develop almost everywhere in the U.S., but the hotspots are the marshes and coasts of the Southeast, and the canyons of Utah, Arizona, and New Mexico.

I'm Stuck in Quicksand Right Now. How Do I Escape?

It’s less difficult to get out than you might think. First, don’t struggle. Remember, you won’t sink all the way in, just to your hips or so if you’re not carrying a pack or wearing heavy gear. Flailing, however, makes you sink deeper by making the quicksand more fluid.

Now, to pull yourself out, start by leaning backwards. Yes, you’re putting more of your upper body in the sand, but it will spread your weight out a little more and improve your buoyancy. You’re basically going to backstroke yourself out from here. Kick your legs slowly to loosen the sand around them and then try to gently bring them up towards the surface. Once your legs and midsection are at or on the surface, gently and slowly paddle with your arms with short strokes along the surface of the quicksand - don’t submerge your hands or arms all the way and get them stuck.

Once you’ve paddled to the edge of more solid ground, pull yourself out. Depending on what type of soil the quicksand is made of and what type of shoes you’ve got on, you might have a hard time pulling your feet completely free because of the quicksand’s suctioning effects. Try and grab a stick and pry your shoes off, but don’t squirm too much or stick your hands in to pull them off.

Quicksand’s Evil Twin

There’s another type of quicksand that’s a little bit scarier than the regular stuff and can cause a person to sink completely — and very quickly. Fortunately, no one has ever confirmed a natural occurrence of it. It’s called dry quicksand and scientists only know it from conditions they created in the lab. Dry quicksand forms when grains of sand form a very loose structure that can barely hold its own weight, let alone yours. In the lab, it’s made by blowing air through the sand, but could be caused naturally by the gradual buildup of sand blown around in the air. Hypothetically, desert winds could create a patch of dry quicksand on the down-wind side of a dune.

While scientists haven’t confirmed dry quicksand in the wild, they don’t discount the possibility that it’s out there. It was a concern during the planning of the Apollo moon missions, and astronomers were worried that the battering of the moon by asteroids and meteorites might have ground some of its surface to a deep, loose layer of debris, soil and dust that would swallow the lunar module whole. To support the craft in the event of these conditions, NASA added large plates to the ends of its legs to help distribute weight.

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May 22, 2012 - 8:01pm
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