Talk:Quicksand

Hi

I've reinstated the granular materials category for quicksand. From a granular materials perspective, quicksand is qualitatively different from regular sand.

I reckon that quicksand is sufficiently conceptually distinct from sand to justify its inclusion in the category. Besides, a user browsing through the category might wish to see quicksand there.

best wishes

Robinh 10:51, 31 May 2005 (UTC)

Hello, everyone. I'm having difficulty with the main premise of many of the statements made on this topic.

My background is geotechnical engineering, not geology - so I spend a lot of time looking at soil mechanics and groundwater movement. From a geotechnical engineering perspective, quicksand isn't a distinct material. In general, it's a combination of fine sands, silts and an upward flow of groundwater. The quick condition occurs when the upward force of the water equals the buoyant weight of the soil particles. Sand boils can occur when the upward flow of water exceeds the velocity needed to form a "quick" condition. There's absolutely no reason to believe that this condition primarily occurs in thin layers, either. In fact, this condition is more likely to form where the soils - and groundwater upflows - are more than 10 feet deep. It's a basic geometry problem - groundwater flow needs to be primarily upward.

Since clays act as a binder, even a small percentage of clay would tend to impart too much strength to the soil. So quicksands would contain very little, if any, clay. And while I have no doubt that a high salt content could create a "hydrogel"-type condition, this is weak ground, not quicksand. Again, if the surface is still, then you have stepped off into very weak ground - probably a silt or organic "mud", not clay. If a hard bottom is encountered within a few feet, then you have a perched groundwater on top of an aquitard - a low permeability clay, clay-shale or similar material. The near-surface soils are probably a mixture of silts, fine sands and some organics. They are saturated, and weak.

In my view, a great many conditions are attributed to "quicksand" when the real cause of the condition is beyond the knowledge or experience of the viewer. These other conditions are very interesting, but they don't belong under this heading.

And by the way, there's no such thing as "super-saturated" when one deals with soil.

Focht3 (talk) 00:29, 20 March 2008 (UTC)

I forgot: the business about quicksand being a non-Newtonian fluid is amusing, but it's utter nonsense.

Focht3 (talk) 00:34, 20 March 2008 (UTC)

Quicksand dangers

It is not to humans. It is to horses and 4x4s. Horses can sink to their bellies and a 4x4 to it's axels. Then you have a problem.

Horses sink only to their bellies? Humans can, if the stuff is not extremely thick, sink to their armpits, thus engulfing 90 percent of a person's body. Seems to me that a 4x4 could sink until it touches bottom or much thicker material. Seems to me that some animals may have a sufficiently high body density and would be 100 percent engulfed. GBC 00:16, 6 March 2006 (UTC)

Verified Deaths?

a friend brought up the following link that talk about deaths from quicksand. Unmuseum article referring multiple deaths. after googling the name, i came across some odd link and a more official sounding account, but the ones from the '60s involving individuals ... how can i put it ... make me raise an eyebrow? considering how benign Mythbusters made it sound, is there any way any of those can be verified? Plonk420 07:56, 11 October 2006 (UTC)

For one thing, don't believe everything you see on Mythbusters. Their methods are entertaining, but not exactly scientific (I'm often a bit appauled by some of the generalisations they make from conducting one experiment). However, in their episode about quicksand, they were only really trying to address Hollywood's typical portrail of quicksand, in which a person steadily gets sucked underground and the more they struggle, the worse it gets. Deaths from becoming partly stuck in quicksand or mud, then drowning with an incoming tide, or dying from exhaustion and exposure are probably not that uncommon. -- Solipsist 10:24, 11 October 2006 (UTC)

The claim that quicksand doesn't kill is nonsense - It is rare for someone to literally drown in quicksand, in the way seen in movies, but quicksand will tend to hold a victim hard and fast - which is a problem somewhere like Morecambe because Quicksand is most active on coastal estuaries where rivers flow into the sea. The tide coming in will tend to liquify more sand. This is why quicksand moves. It is not always safe to take the same path through it twice. Quicksand kills by holding victims until the sea claims them, or through hypothermia, when the victim is trapped in the cold mud, and exhausted by struggling to get free. Liquification can also turn solid sand to quicksand in Earthquakes. This is especially dangerous where land has been reclaimed from the sea and buildings raised on coastal landfill, as happened in San Francisco in 1906. Even today, with more quakes there being imminant, the same building policy is used. If and when a big quake strikes, thousands could be killed by quicksands swallowing skyscraper foundations. (User:arthurchappell

So, any references for people killed after being trapped in quicksand? I have seen, walked on, and taken samples of quicksand, and find it completely unbelievable that a person could actually get stuck in it. I think people are confusing quicksand with simply deep mud. Quicksand is hard and easy to walk on, it needs to be agitated vigorously to liquify, and then it is still very dense, denser than water, and far more slow-flowing. Constructions are in danger from it because it may shift, but humans? Not so much. This article seems little more than folklore.213.114.237.26 (talk) 09:55, 15 October 2008 (UTC)

Function of salt in quicksand

Findings about the crucial role of salt in quicksand published in September 2005 in Nature: http://www.nature.com/nature/journal/v437/n7059/full/437635a.html

Cleaned up some slightly incorrect statements about the nature of quicksand and provided a more detailed explanation of the "trapping" mechanism.

The paragraph that was deleted / heavily modified follows below, just in case someone does not approve of my updates:

Quicksand is loose, water-logged soil that yields easily to weight or pressure. It can be formed when sand, silt, clay, or other grainy soil is saturated or supersaturated by water flowing from below ground (such as from an underground spring) with enough pressure to separate and suspend the grains. The undisturbed sand often is or appears to be solid until some shock or sudden increase in pressure, such as a person stepping on it, causes it to liquify and lose its friction.

Also, maybe the "liquefaction in quicksand" section of the Soil liquefaction entry should be updated.

much love and many blessings =)

Iamthepattern 12:50, 28 March 2006 (UTC)

Given the new information about how quicksand works, what changes in terms of the methods of how to rescue a person caught in it, and what are the methods that a lone individual would use to extract himself? GBC 22:39, 10 July 2006 (UTC)

While salt may make quicksand less stable, quicksand may be found along the banks of rivers, at the base of dams, and over springs where fresh water flows up through the soil. There are many examples of freshwater quicksands. The description of quicksand should not be limited to salt water. Naaman Brown 18:17, 30 July 2007 (UTC)

Quicksand in 80s movies

It says in the article "It is unclear why so many television shows and movies from the 1980s depicted quicksand as such a threat. There are no reported deaths from quicksand inhalation." Why only from the 80s? There are loads of other depictions from other years. Also, There are no reported deaths from quicksand inhalation. Well probably not because it would act like a 1iquid and drown them. Think outside the box 13:14, 22 March 2007 (UTC)

Not just movies in the 80s, the new Indiana Jones movie has quicksand (I mean the new one that just came out, where it turns out the crystal skulls were actually alien skulls from an alternate dimension who taught early civilization knowledge and awareness) JayKeaton (talk) 12:31, 22 May 2008 (UTC)

Surviving Quicksand

What's a good strategy to maximize one's chances of survival? Is it better to give up one's breath early to make use of the dead-man's float or is it better to save one's breath and float on one's back? --Thelazyleo (talk) 18:38, 20 August 2008 (UTC)

This isn't directly related to falling into quicksand and getting out but, is it rue that you can run across quicksand (so you get across before decrease in viscosity)?

Alkali bogs

A 1950s article in Scientific American about quicksand also mentions a variation called an alkali bog, prevalent in the western United States. This version of quicksand does not involve any water, rather, salt seeps produce a condition -- which may also occur on inclines -- similar to quicksand, but with the consistency of soft soap. It is possible to identify it by whitish marks on otherwise normal-coloured sand. Although the article states that an individual must move far faster to escape, and that such bogs are littered with the bones of animals that did not "move fast enough", it does not state whether the density of an alkali bog is low enough to engulf a human being. I do have photocopies of the entire article, but I do not know at this time where I have it stored. GBC (talk) 09:22, 13 September 2008 (UTC)