Quicksand

Quicksand

Quicksand is a colloid hydrogel consisting of fine granular matter (such as sand or silt), clay, and salt water. In the name, as in that of quicksilver (mercury), "quick" does not mean "fast," but "alive" (cf. the expression "the quick and the dead").

Water circulation underground can focus in an area with just the right mixture of fine sands and other materials such as clay. The water moves up and then down slowly in a convection-like manner throughout a column of sand under optimal conditions, and the sand remains a generally solid mass. This lubricates the sand particles and renders them unable to support any significant weight, since they move around with very little friction, behaving more like a liquid when exposed to stress. Since the water does not usually go all the way up through the sand, the sand above does not appear to move at all, and can support leaves and other small debris, making quicksand difficult to distinguish from the surrounding environment.

Properties

Quicksand is a non-Newtonian fluid: when undisturbed it often appears to be solid ("gel" form), but a minor (less than 1%) change in the stress on the quicksand will cause a sudden decrease in its viscosity ("sol" form). After an initial disturbance—such as a person attempting to walk on it—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 in it will start to sink. In order to move within the quicksand, a person or object must apply sufficient pressure on the compacted sand to re-introduce enough water to liquefy it. The forces required to do this are quite large: to remove a foot from quicksand at a speed of one centimeter per second would require the same amount of force as "that needed to lift a medium-sized car." "A. Khaldoun, E. Eiser, G. H. Wegdam and Daniel Bonn [http://www.nature.com/nature/journal/v437/n7059/full/437635a.html Rheology: Liquefaction of quicksand under stress] " 'Nature' Vol. 437, Pg. 635, 29 September 2005 doi|10.1038/437635a]

Recent research findings

It was commonly believed that the behavior of quicksand was due solely to saturated or supersaturated suspensions of granules in water. Pressure from underground sources of water would separate and suspend the granular particles, reducing the friction between them. As of September 2005, it has been shown that it is the presence of salt that is largely responsible. The stability of the colloidal quicksand is compromised by the presence of salt, increasing the likelihood of sand flocculation and the formation of the high viscosity regions of sediment responsible for quicksand's "trapping" power.

Prevalence

Quicksand may be found inland (on riverbanks, near lakes, or in marshes), or near the coast.

One region notorious for its quicksands is Morecambe Bay, England. As the bay is very broad and shallow, a person trapped by the quicksand would be exposed to the danger of the returning tide, which can come in rapidly.

ee also

*Dry quicksand
*Fech fech
*Liquid limit
*Plastic limit
*Soil liquefaction
*Thixotropy

References

External links

* [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/print_version.cfm?articleID=000D6BF9-5CDF-1D9C-815A809EC5880000 | work =Scientific American | pages = | accessdate = | language =
* [http://www.dellamente.com/quicksand/ Quicksand in Fiction]
* [http://www.youtube.com/watch?v=0IZT-AHPxQs Brainiac on Quicksand (Youtube)]


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  • Quicksand — Saltar a navegación, búsqueda Quicksand Información personal Origen Nueva York Estados Unidos Información artística Género(s) …   Wikipedia Español

  • Quicksand — Quick sand , n. Sand easily moved or readily yielding to pressure; especially, a deep mass of loose or moving sand mixed with water, sometimes found at the mouth of a river or along some coasts, and very dangerous, from the difficulty of… …   The Collaborative International Dictionary of English

  • Quicksand — Allgemeine Informationen Genre(s) Post Hardcore Hardcore Punk Gründung 1990 Auflösung 1998 …   Deutsch Wikipedia

  • Quicksand — Quicksand, 1) Sand, dessen Körner eckig sind; 2) so v.w. seiner Sand …   Pierer's Universal-Lexikon

  • quicksand — (n.) c.1400, from M.E. quyk living (see QUICK (Cf. quick)) + sond sand (see SAND (Cf. sand) (n.)). Old English had cwecesund, but this might have meant lively strait of water …   Etymology dictionary

  • quicksand — ► NOUN (also quicksands) ▪ loose wet sand that sucks in anything resting on it …   English terms dictionary

  • quicksand — [kwik′sand΄] n. [ME quykkesand: see QUICK & SAND] a deep, semifluid deposit or bed of sand in which an animal, heavy object, etc. may be trapped or engulfed …   English World dictionary

  • Quicksand — Cette page d’homonymie répertorie les différents sujets et articles partageant un même nom. Quicksand signifie sable mouvant en anglais. Sommaire 1 Cinéma et télévision 2 …   Wikipédia en Français

  • quicksand — quicksandy, adj. /kwik sand /, n. a bed of soft or loose sand saturated with water and having considerable depth, yielding under weight and therefore tending to suck down any object resting on its surface. [1275 1325; ME qwykkesand. See QUICK,… …   Universalium

  • quicksand — [[t]kwɪ̱ksænd[/t]] quicksands 1) N UNCOUNT: also N in pl Quicksand is deep, wet sand that you sink into if you try to walk on it. 2) N UNCOUNT, also N in pl You can refer to a situation as quicksand when you want to suggest that it is dangerous… …   English dictionary

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