Death in quicksand is a favorite plot of directors of low-budget films. But can the sands actually swallow a person? The BBC Future columnist decided to delve into this issue.
We've all seen this in movies. A person falls into quicksand, calls for help, but the more he resists, the deeper he plunges into the bog and finally disappears altogether - and now nothing is visible except the terrible sand and, perhaps, the hat of the deceased.
Death in quicksand is such a pervasive storyline that Daniel Engbar, a reporter for the English-language online magazine Slate, even set out to find out which years it was most exploited.
So, in the 60s of the last century, quicksand appeared in every thirty-fifth film. They met everywhere - from the epic film Lawrence of Arabia to the comedy series Monkeez.
However, there are not very many data in favor of the fact that, wallowing in the sand, a person sinks deeper into it and drowns.
Quicksands usually consist of sand or clay and moisture-saturated salt and are most commonly found in river deltas. Their surface looks solid, but as soon as a human foot steps on it, the sand begins to liquefy.
The water and sand then separate, forming a compacted layer of wet sand that can easily get stuck in. The friction between the grains of sand is greatly reduced, and they can no longer support the weight of the person, so that he really begins to bog down.
It is also true that violent attempts to get out can cause an even deeper sinking into the sand. But can a person drown in it?
Promotional video:
During his trip to Iran, Daniel Bonn, a researcher at the University of Amsterdam, noticed signs near a lake warning tourists about the danger of quicksand.
He took a small sample to the laboratory, analyzed the ratio of clay, salt water and sand, and then recreated the quicksand based on the obtained proportion - for the experiment.
Instead of people, he used aluminum bars, similar in density to the human body.
He placed them on a mountain of sand, and then began to swing, imitating the feverish movements of a man trying to get out to see if the bars would drown in the sand.
But they didn't drown. At first they sank slightly into the sand, but gradually it began to mix with water again, its buoyancy increased, and the bars rose back to the surface.
Bonn and his colleagues tried to put a variety of objects on quicksand, obtained in laboratory conditions. If in density they were similar to the human body, they were immersed in the sand, but not completely, but only half.
But if, according to the laws of physics, the body cannot endlessly sink into the sand deeper and deeper, why do people tragically die from time to time in quicksand, as happened in 2012 with a mother of two children, who was vacationing in Antigua?
The reason is that, although quicksand does not suck in a person, if he does not free himself in time, he can be covered by a tidal wave. In this case, quicksand can indeed be dangerous.
So, convulsive attempts to get out of the sand will not lead to death by themselves, but you still need to be careful.
If you want to free yourself without waiting for someone to help you or until the sand starts to liquefy again, then, as Bonn's research has shown, in order to free at least one leg, you need to apply a force of 100 thousand newtons - this is about the same, how much it takes to lift a midsize car into the air.
In the laboratory, Bonn and his colleagues found that salt is an integral part of quicksand, which makes them quicksand, which leads to the formation of such dangerous areas of dense rock.
But then another group of scientists - this time from Switzerland and Brazil - discovered a type of quicksand that did not contain salt.
The study analyzed sand samples taken from a lagoon in northeastern Brazil. It turned out that bacteria are present on the surface of the soil, forming a crust, which gives the impression of solid soil, but falls through when you step on it. However, even in this case, not everything is so bad: the depth of such sand is very rarely more than human height, so even getting stuck in this quagmire, a person, most likely, will not drown.
Dry bogs, however, are a completely different matter. So, getting into a filled grain storage is often fatal precisely due to the effect of quicksand.
In 2002, a story was published about how a man fell into an elevator late at night on a German farm.
By the time the firefighters determined which of the eight containers he was in, the grain was reaching his armpits and, in full accordance with the classic principles of quicksand, it was sucking him deeper and deeper. With each exhalation, his chest clenched, and the vacated space was immediately occupied by grain, which made it increasingly difficult to breathe.
A doctor with an oxygen mask for the victim descended into the container on a rope, and straps were fastened around his chest. However, he soon developed intolerable chest pains, and the doctor suffered an asthma attack from the dust.
But the firefighters were not at a loss: they came up with the idea of lowering a cylinder from above and pumping out the grain in an industrial way. The grain ceased to squeeze the fallen man so hard, and he was saved.
A person trapped in a dry bog can only survive if he is promptly assisted. But what if you are caught in wet sand and do not drown, but are stuck?
In this case, it is recommended to move your leg so that water comes out around your foot - and the sand would turn into slime again.
The key is to stay calm (which is, of course, not easy!), Lean back and flatten on the surface to distribute your weight more evenly.
And then you just have to wait until you are pushed up again. Yes, and don't forget your hat!
Claudia Hammond