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Leon County Democrat Group

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Wyatt Reed
Wyatt Reed

Quicksand [NEW]


The saturated sediment may appear quite solid until a sudden change in pressure or shock initiates liquefaction. This causes the sand to form a suspension and lose strength. The cushioning of water gives quicksand, and other liquefied sediments, a spongy, fluid-like texture. Objects in liquefied sand sink to the level at which the weight of the object is equal to the weight of the displaced soil/water mix and the submerged object floats due to its buoyancy.




Quicksand



It is impossible for a human to sink entirely into quicksand,[2] due to the higher density of the fluid. Quicksand has a density of about 2 grams per cubic centimeter, whereas the density of the human body is only about 1 gram per cubic centimeter. At that level of density, sinking beyond about waist height in quicksand is impossible. Even objects with a higher density than quicksand will float on it if stationary. Aluminium, for example, has a density of about 2.7 grams per cubic centimeter, but a piece of aluminium will float on top of quicksand until motion causes the sand to liquefy.[3]


Continued or panicked movement, however, may cause a person to sink further in the quicksand. Since this increasingly impairs movement, it can lead to a situation where other factors such as weather exposure (i.e. sun stroke), dehydration, hypothermia, drowning in a rising tide or predatory animals may harm a trapped person.[4]


Quicksand is a trope of adventure fiction, particularly in film, where it is typically and unrealistically depicted with a suction effect that causes people or animals that walk into it to sink until fully submerged and risk drowning. This has led to the common misconception that humans can be completely immersed and drown in quicksand; however, this is physically impossible.[7] According to a 2010 article by Slate, this gimmick had its heyday in the 1960s, when almost 3% of all films showed characters sinking in clay, mud, or sand.[8]


For many of us, quicksand was once a real fear -- it held a vise-grip on our imaginations, from childish sandbox games to grown-up anxieties about venturing into unknown lands. But these days, quicksand can't even scare an 8-year-old. In this short, we try to find out why.


Producer Soren Wheeler introduces us to Dan Engber, writer and columnist for Slate, who ran across a strange fact: kids are no longer afraid of quicksand. To figure out what happened to quicksand, Dan immersed himself in research, compiled mountains of data, and met with quicksand fetishists. Dan tells Soren and Robert about his journey, and shares his theory about why the terror of his childhood seems to have lost its menacing allure. And Carlton Cuse, best-known as writer and executive producer of Lost, weighs in on whether giant pits of hero-swallowing mud might one day creep back into the spotlight.


Of persons, "mentally active, prompt to perceive or respond to impressions" from late 15c. Of an action, process, etc., "done in little time," 1540s. Also in Middle English used of soft soils, gravel pits, etc. where the ground is shifting and yielding (mid-14c., compare quicksand). Also in Middle English "with child, in an advanced state of pregnancy" (when the woman can feel the child move within). Also formerly of bright flowers or colors (c. 1200).


"The higher the stress, the more liquid the quicksand becomes, so movement by a trapped body causes it to sink in deeply," study leader Daniel Bonn of the University of Amsterdam writes in the Sept. 29 issue of the journal Nature.


After the mix liquefies, the quicksand splits into a water-rich phase and a sand-rich one. The wet sand sediment becomes so densely packed that it's harder to move than cold molasses. Once the victim's foot becomes stuck in it, the situation is dire.


"If you move into the quicksand, this loose packing will collapse," Bonn told LiveScience. "We then have densely packed sand at the bottom, and water floating on top of it. It's the difficulty of getting water into this very densely packed sand that makes it difficult for you to pull your foot out."


The researchers simulated a quicksand pit in the lab and placed an aluminum ball of greater density than the quicksand on top of the pit. The ball didn't sink until the researchers began to shake the pit, simulating movement and turning the mixture of sand and water more liquid. When they did this, the ball sank right to the bottom.


But when they used an aluminum ball with a density equal to the human body, which is less than the density of quicksand, they found it impossible to sink the ball, no matter how hard they shook the pit.


According to a study published in the current issue of the journal Nature, it is impossible for a person immersed in quicksand to be drawn completely under. The fact is, humans float in the stuff.


Researchers in the Netherlands and France studied quicksand, a combination of fine sand, clay, and salt water. At rest, quicksand thickens with time, but it remains very sensitive to small variations in stress.


Quicksand is a mixture of sand and water, or sand and air, that looks solid, but becomes unstable when disturbed by any additional stress. In normal sand, grains are packed tightly together to form a rigid mass, with about 25 to 30 percent of the space (voids) between the grains filled with air or water. Because many sand grains are elongate rather than spherical, loose packing of the grains can produce sand in which voids make up 30 to 70 percent of the mass. This arrangement is similar to a house of cards in that the space between the cards is significantly greater than the space occupied by the cards. The sand collapses, or becomes 'quick,' when additional force from loading, vibration or the upward migration of water overcomes the friction holding the grains together. Most quicksand occurs in settings where there are natural springs, either at the base of alluvial fans (cone-shaped bodies of sand and gravel formed by rivers flowing from mountains), along riverbanks or on beaches at low tide. In such cases, the loose packing is maintained by the upward movement of water. Quicksand does occur in deserts, but only very rarely: where loosely packed sands occur, such as on the down-wind sides of dunes, the amount of sinking is limited to a few centimeters, because once the air in the voids is expelled the grains are too densely packed to allow further compaction.Answer originally published on October 7, 2002. Rights & PermissionsRead This NextDark MatterVera Rubin Lives on in Lives of the Women She Helped in AstronomyTulika Bose


Such truisms sidestep a deeper, stickier question: Why does one gag fall by the wayside while another soldiers on? Movie villains have long since given up tying their victims to the railroad tracks, yet they never seem to weary of planting time bombs. (Think how many colored wires were snipped in The Hurt Locker.) And quicksand? Time was, a director could sink a man in the desert and still win the Oscar for best picture. Today, that gimmick has been scorned in third-rate schlock.


Before we can answer those questions, let's pinpoint when quicksand's status began to falter. Carlton Cuse, the longtime television producer, offers a clue. He didn't write any quicksand into Lost, but he did put some in another show, years earlier. In the seventh week of the first season of The Adventures of Brisco County Jr., the title character is captured by a Wild West pirate and thrown in a pool of sinking mud. So there you have it: For one pop-culture professional, at least, the gag still had its mojo back in October 1993. By the time the Lost pilot was aired in the fall of 2004, it had disappeared.


By the mid-1990s, individual quicksand fans were already conducting their own private surveys of the genre, and making libraries of scenes dubbed to VHS. With communication came the possibility of collaboration, and a more structured way to assemble this knowledge. Clips were shared over the Internet, and the community began working together to dig up new, undiscovered examples of quicksand cinema. They scoured the shelves at video-rental stores for movies with island or jungle in their titles. They sifted through IMDB plot summaries and discussed ways to keep the metaphorical uses of quicksand from polluting their Google searches. (References to the New York-based post-hardcore band Quicksand proved especially annoying.) And sometimes they relied on dumb luck: One day, Duncan Edwards happened to pick up a copy of Life magazine from 1961 at a flea market, and, flipping through the pages, found a film publicity still showing pin-up girl Anita Ekberg sinking in a pool of sand and water. He shared the news, and the race was on for the original footage. "The search is endless," says Edwards, "it goes on and on and on."


For those with "the interest," the guide serves as an enormous Netflix queue, a sort of collector's catalog or a fetish to-do list. For everyone else, it's a sui generis chronicle of America's preoccupation with quicksand. If Carlton Cuse of Lost is right that adventure gags must evolve, then Crypto's List is the nearest we have to a fossil record.


As a child of the Reagan years, I thought I'd seen the glory days of quicksand: What depths we reached, at The Neverending Story (1984), when Artax sank in the Swamps of Sadness, and what joy at seeing Buttercup saved from the muck in The Princess Bride (1987). I know my brother spent hours dodging pools of deadly tar in Pitfall!, the 1982 Atari cartridge that remains one of the most popular video games of all time.


But for all that, the quicksand of our youth was already an endangered resource. By the time I entered junior high, the gag had been relegated to self-conscious horror flicks and zany sitcoms like Perfect Strangers and Small Wonder. Quicksand was ironized and depleted. Across the 1980s, it appeared in roughly one of every 75 films released in the theaters. That's more than twice as much quicksand as we have today but less than half the total from just a few years earlier. 041b061a72


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