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Biography
about|the geological feature Quicksand is a colloid hydrogel consisting of fine granular material (such as sand or silt ), clay , and water .
Quicksand forms when water saturates an area of loose sand and the sand is agitated. When the water trapped in the sand cannot escape, it creates liquefied soil that cannot support weight. Quicksand can be formed by standing or (upwards) flowing underground water (as from an underground spring), or by earthquakes. In the case of flowing underground water, the force of the water flow opposes the force of gravity, causing the granules of sand to be more buoyant. In the case of earthquakes, the shaking force can increase the pressure of shallow groundwater, liquefying sand and silt deposits. In both cases, the liquefied surface loses strength, causing buildings or other objects on that surface to sink or fall over.
The saturated sediment may appear quite solid until a change in pressure or shock initiates liquefaction. This causes the sand to form a suspension, with each grain surrounded by a thin film of water. This cushioning gives quicksand, and other liquefied sediments, a spongy, fluidlike texture. Objects in the liquefied sand sink to the level at which the weight of the object is equal to the weight of the displaced sand/water mix and the object floats due to its buoyancy.
Properties
Quicksand is a non-Newtonian fluid : when undisturbed, it often appears to be phase (matter)|solid (" gel " form), but a minor (less than 1%) change in the stress (physics)|stress on the quicksand will cause a sudden decrease in its viscosity (" sol (colloid)|sol " form). After an initial disturbance & mdash; such as a person attempting to walk on it & mdash; the water and sand in the quicksand separate and dense regions of sand sediment form; it is because of the formation of these high volume fraction regions that the viscosity of the quicksand seems to increase suddenly. Someone stepping on it will start to sink. To move within the quicksand, a person or object must apply sufficient pressure on the compacted sand to re-introduce enough water to liquefaction|liquefy it. The force s required to do this are quite large: to remove a foot from quicksand at a speed of .01 m/s would require the same amount of force as "that needed to lift a medium-sized car."Khaldoun, A., E. Eiser, G. H. Wegdam, and Daniel Bonn. 2005. http://www.nature.com/nature/journal/v437/n7059/full/437635a.html "Rheology: Liquefaction of quicksand under stress." Nature 437 (29 Sept.): 635. doi|10.1038/437635a
Because of the higher density of the quicksand, it would be impossible for a human or animal to completely sink in the quicksand, though natural hazards present around the quicksand would lead people to believe that quicksand is dangerous. In actuality the quicksand is harmless on its own, but because it greatly impedes human locomotion, the quicksand would allow harsher elements like solar radiation , dehydration , hypothermia or tides to harm a trapped person. Discovery Channel . MythBusters . Season 2. MythBusters_(season_2)#Episode_19_.E2.80.93_.22Killer_Quicksand.22|"Killer Quicksand." October 20, 2004. The way to escape is to wiggle the legs, to move as slowly as possible in order to reduce viscosity, to try spreading your arms and legs far apart and leaning over to increase your surface area, which should allow you to float.cite web |url= http://news.nationalgeographic.com/news/2005/09/0928_050928_quicksand.html |title=Quicksand Science: Why It Traps, How to Escape |first1=Nicholas |last1=Bakalarfor |publisher= National Geographic News |date=September 28, 2005 |accessdate=October 9, 2011
Prevalence
Quicksand may be found inland (on riverbanks, near lake s, or in marsh es), or near the coast.
In fiction
People falling into (and, unrealistically, being submerged in) quicksand or a similar substance is a Trope (literature)|trope of adventure fiction , notably movies. According to Slate (magazine)|Slate , this gimmick had its heyday in the 1960s, when almost 3% of all films showed someone sinking in mud, sand, or clay, but it has since fallen out of use. The proliferation of quicksand scenes in movies has given rise to an Cyberculture|internet subculture scene dedicated to the topic.cite news|last=Engber|first=Daniel|title=Terra Infirma: The rise and fall of quicksand.|url= http://www.slate.com/id/2264312/|accessdate=23 August 2010|newspaper=Slate|date=23 August 2010
See also
Bill Smith (Fell runner)
Dry quicksand
References
External links
Commons category-inline|Quicksand
http://science.howstuffworks.com/quicksand.htm Howstuffworks.com - How quicksand works
cite news | first= | last= | coauthors= | title=What is quicksand? | date= | publisher= | url = http://www.sciam.com/article.cfm? id=what-is-quicksand | work =Scientific American | pages = | accessdate = | language =
http://www.funham.com/how-to-get-out-of-quicksand/ How to get out of quicksand Video
