Editing Quicksand (section)

== Properties ==
[[File:Stuck in Quicksand (13944309974).jpg|thumb|A group of hikers encountering quicksand on the banks of the [[Paria River]], Utah]]
[[File:Quicksandwarning.JPG|thumb|Quicksand warning sign near [[Lower King, Western Australia|Lower King]] Bridge, Western Australia]]
Quicksand is a [[shear thinning]] [[non-Newtonian fluid]]: when undisturbed, it often appears to be [[phase (matter)|solid]] ("[[gel]]" form), but a 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—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 decrease 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 1&nbsp;cm/s would require the same amount of force as that needed to lift a car.<ref name="Bonn">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}}</ref>

It is impossible for a human to sink entirely into quicksand,<ref name=":0">{{Cite web|url=http://thescienceexplorer.com/nature/will-quicksand-really-kill-you|title=Will Quicksand Really Kill You?|website=The Science Explorer|language=en|access-date=2020-04-08}}</ref> 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.<ref name=Bakalar>{{cite web |url=https://www.nationalgeographic.com/science/article/quicksand-science-why-it-traps-how-to-escape/ |archive-url=https://web.archive.org/web/20210221081902/https://www.nationalgeographic.com/science/article/quicksand-science-why-it-traps-how-to-escape |url-status=dead |archive-date=February 21, 2021 |title=Quicksand Science: Why It Traps, How to Escape |first1=Nicholas |last1=Bakalar |publisher=[[National Geographic News]] |date=September 28, 2005 |access-date=October 9, 2011}}</ref>

Continued or panicked movement, however, may cause a person to sink further in the quicksand.<ref>{{cite news |last1=Gleeson |first1=Bill |title=Sinking sand is notorious near Crosby - here's what you need to know |url=https://www.liverpoolecho.co.uk/news/liverpool-news/sinking-sand-notorious-near-crosby-11794759 |work=Liverpool Echo |date=24 August 2016 |language=en}}</ref> Since this increasingly impairs movement, it can lead to a situation where other factors such as exposure (i.e., [[heat stroke|sun stroke]], [[dehydration]] and [[hypothermia]]), [[drowning]] in a rising [[tide]] or [[animal attack|attacks]] by [[Predation|predatory]] or otherwise aggressive animals may harm a trapped person should they not be rescued.<ref>[[Discovery Channel]]. ''[[MythBusters]]''. Season 2. [[MythBusters (2004 season)#Episode 19 .E2.80.93 .22Killer Quicksand.22|"Killer Quicksand."]] October 20, 2004.</ref>

Quicksand may be escaped by slow movement of the legs in order to increase viscosity of the fluid, and rotation of the body so as to float in the [[supine position]] (lying horizontally with the face and torso facing up).<ref name=Bakalar/>