What is quicksand. How to get out of quicksand
Walking somewhere in nature, enjoying the charm of flowering plants, listening to birds whistling cheerful songs, you can accidentally find yourself in a trap, falling into quicksand. But you should immediately warn that everything is not so scary, as shown in some films of the "horror" genre. Yes, of course, it is better to avoid them, but at the same time, you should not be afraid. There are several consistent rules, the knowledge of which will help to avoid such situations.
What exactly is quicksand? It's really interesting, but not at all peculiar. A mixture of fine-grained material, clay and water (in desert places - a mixture of sand and air). It looks solid, but becomes unstable when pressure is applied to its surface. It is formed when water oversaturates such soil. Ordinary, naturally occurring sand (quarry, mountain, sea) consists of densely packed grains that form a rigid mass (approximately 25 to 30 percent of the space between the grains is filled with water or air). Since many grains of sand are elongated, they can separate, and then the voids will be from 30 to 70 percent of the mass. This mechanism is similar to a house of cards when the space between the cards is significantly larger than the space they occupy. The liquid contributes to the creation of liquefied soil, which is not able to withstand the weight load.
Quicksand can form in stagnant and flowing upward water (as in artesian springs). Water jets directed upwards resist and inhibit soil particles. Saturated precipitation may look quite solid, but a little on its surface initiates liquefaction. This causes the sand to form into a slurry and lose strength. Cushioned water produces quicksand, liquefied sediments, and a spongy, liquid-like soil texture. Objects entering such an environment sink to a level at which their weight is equal to the weight of the displaced mixture (from soil and water). Liquefaction - a special case the phenomenon under consideration. So, in the event of an earthquake, the pore pressure instantly increases in shallow areas. Wet liquefied soil loses its strength, which leads to the collapse of buildings and other objects located on its surface.
Quicksands form where natural springs exist, in marshy or wet places, near rivers, on beaches, although most often they are not so easy to identify. If you suddenly get into them, they retreat quickly and gently, reacting with an interval of a couple of seconds. They are, that is, at rest they are a solid substance (gel-like form), but the slightest impact on them causes a sharp decrease in viscosity. In deserts, they are also found, but extremely rarely, where placers of sand appear, for example, on dunes. But the decline is limited to a few centimeters, because as soon as the air in the voids between the sand grains is removed (and this happens quickly), they re-compact.
Quicksand - sands that are oversaturated with water from ascending sources, they are able as a result of this to suck in objects, animals and humans that fall on them. Quicksand is diverse in nature. Due to the thin water film that envelops the grains of sand, the adhesion between them is sharply reduced, and these sands behave almost the same as a liquid: a foreign body continues to sink until the weight of the sand it displaces is equal to the weight of the body itself.
The suction rate depends on the structure of the sand, the mass and volume of the foreign object and can vary from several minutes to several months.
terrible danger
There are many legends and dark stories associated with these sands. The terrible danger lurking under the surface of the sand, at first glance, seems so harmless.
Tarnagen Fjord in Alaska a nice place, in 1988, two tourists, a married couple Dixon, decided to ride along the coast at low tide. The car got stuck in the sand. Adreanna Dixon got out of the car and immediately fell into the sand up to her knees. The husband tried for several hours to help his wife, but could not free her from the trap. The sand was compressed and held the legs like cement. The husband called the rescue team, but the fjord was already high tide. It was not possible to save the woman from sandy captivity - the unfortunate woman drowned.
Action of quicksand (how it happens)
Why do people fall into quicksand? It's all about the special structure of the arrangement of grains of sand. The water flow coming from below whips up a loose cushion of grains of sand, which is in comparative equilibrium for some time. The weight of a traveler who finds himself in such a place brings down the structure. The grains of sand, being redistributed, begin to move along with the body of the unfortunate person, additionally, as if they are sucking the victim into the soil layer. After that, the structure of the sand around the victim changes completely - tightly pressed wet grains of sand form a trap due to the surface tension of the water layer.
When you try to pull your leg out, a rarefaction of air is formed, which pulls the leg back with great force. In order to extend the leg in such a situation at a speed of 0.1 m/s, it is necessary to apply a force equal to the lifting force of a medium-sized car. So, when you get into quicksand, it is advised not to make sudden movements, but to try to lie on your back and, with your arms outstretched, wait for help.
nature of quicksand
To this day, scientists have not been able to fully understand the nature of this dangerous phenomenon. Some of the researchers believe that the ability to suck is determined by the special shape of the grains of sand. According to one of the versions proposed by the Russian physicist V. Frolov, the mechanism of action of quicksand is due to electrical effects, as a result of which the friction between the grains of sand becomes much less and the sand becomes fluid. If the fluidity extends to a depth of several meters, the soil becomes viscous and sucks in any massive body that is on it.
Geologist George Clark from the University of Kansas (America) has been studying the unique phenomena of sand for many years and came to the conclusion that quicksand is ordinary sand that is mixed with water and has some properties of a liquid medium. According to Clark, fluctuation is not a natural phenomenon, but a special state of sand. The latter occurs, for example, on a surface periodically flooded by the tide, or if an underground river flows under a sand massif.
Usually quicksands are located in hilly areas where underground water flows often change direction and can rise to the surface or go deep.
Why you can get out of dry sand
With dry sand, everything is different: even up to the neck of a buried person, you can gradually get out of it on your own, because when you move slowly, air first enters the free space, and then grains of sand begin to fill the niche. In quicksand, there is no such air, and the suspension can be compared to jelly in its consistency, and the slowly moving mass will not have time to fill the resulting cavity, forming a vacuum.
There are two kinds of quicksand
1. With a wet surface. It can be found on the shores of lakes, rivers, seas, where rising sources are often present. On top there may be a thin crust of silt formed from a fine fraction of sand.
2. With a dry surface. They are found in the desert and in rocky areas.
On the English coasts
Most legends about quicksand originated in Britain on the sea coasts, where for centuries there were dangerous areas that sucked in a person or animal who carelessly stepped on a deceptive surface.
Excerpt from the novel by W. Collins "Moonstone":
“Between two rocks lies the most terrible quicksand on the entire Yorkshire coast. At high and low tide, something happens in their depths, causing the entire surface of the sands to oscillate in the most unusual way ... Secluded and scary place!.. Not a single boat dares to enter this bay... Even the birds fly away from the quicksand. The tide began to rise, and the terrible sand began to shudder. Its brown mass slowly rose, and then it all trembled…”
Also in XIX century most of these dangerous places in England fell asleep and destroyed. Currently, there are no quicksands in densely populated areas.
happy rescue
1999 - Arnside (England), in front of his parents, the sand sucked up to the waist of a 4-year-old son. Fortunately, the rescue team arrived in time, and the tragedy did not happen. Arnside is close to Morecambe Bay which is famous for its high tides. At low tide, the water recedes by 11 km, and the sandy bottom of the bay is exposed. Daredevils who dare to step on this sand, which seems like solid ground, are instantly sucked in. The hardened mass squeezes the legs, and it is impossible to pull them out without someone's help. If this is not done in a timely manner, a person will die under the water of the tide (the water rises 9 meters!), As happened with Adreanna Dixon. More than 150 people died there in a few years.
Beware of quicksand
Notorious among the sailors received, located in Atlantic Ocean 180 km from the coast of Canada, near which there are many reefs, because of which ships often crashed there and were washed ashore. As the months passed, the sand sucked the wreckage without a trace. There are a lot of dangerous sandy quicksands in Alaska, the longest of the peninsula's fjords, completely filled with quicksand, 150 km long.
And in the Sahara, one of the most arid and lifeless deserts on Earth, there are quicksands. Entire caravans disappear without a trace. Nomads from the Tuareg tribe talk about heartbreaking screams that come from under the ground at night. They believe that this is the groaning of the souls of people who were swallowed up by the ruthless belly of the desert. Relatively not so long ago, Russian scientists made a discovery based on satellite photographs of the earth's surface - a powerful underground river flows under the desert. It is likely that the waters of this river give some places of the desert the properties of quickness.
Tragedy of Port Royal
It is difficult to even roughly estimate the number of victims of the deadly sands, in any case, it exceeds thousands, and possibly tens of thousands. 1692 - In Jamaica, quicksand swallowed up an entire area of the city, then more than 2,000 people died. Port Royal was a very large rich port, where the largest slave market was located. Since 1674, upon the appointment of the English monarch Charles II, the legendary pirate was appointed mayor of the city. But the place for the construction of the city was chosen extremely unsuccessfully. Port Royal was located on a 16-kilometer sandbar. Its upper layer is still saturated with water today, and below is a mixture of gravel, sand and rock fragments.
1692, June 7 - an earthquake began, and the sand under the city suddenly began to suck in buildings and people. Descriptions of the tragedy have been preserved in the historical chronicle. Some of the inhabitants of the city instantly fell into the ground, others were sucked up to the knee or to the waist.
After the earthquake ended (it lasted six minutes), the sand instantly turned into a solid mass that resembled cement, it tightly clamped people in its vise. People were suffocating, buried alive in the ground. Most of them died, unable to get out, their bodies sticking out of the sand were eaten by feral dogs. Back in the 19th century, on the site of the buried city, the remains of the walls of collapsed houses protruded from the sand. And in 1907 there was another earthquake that swallowed up these silent testimonies of the tragedy.
goodwin shallows
The South Foreland in England, where the Goodwin Shoals are located, has a grim notoriety as a "ship graveyard". There, on a vast shoal, ships are half-buried. Only what remains of the masts and rusty pipes of the former conquerors of the seas stick out of the sand. The sands tenaciously hold their victims, and it is almost impossible to save the ships.
1946 - the ship "Gelena Modjeska" became a victim of the Goodwin Sands, the cargo of which was estimated at three million dollars. On September 12, the ship ran aground off the southern tip of South Forland. For four days, 8 rescue tugs tried to save the steamer, but on the 5th day, the Helena Modjeska broke in half, and the cargo and the steamer fell victim to the sands.
1954 - in this place, the sands swallowed up a lighthouse that warned ships of danger. The tragedy happened so quickly that the arriving helicopter managed to save only one worker from the tower that had almost sunk into the sand.
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Quicksand is a deadly attraction. The main danger lies in the fact that they are almost impossible to distinguish from ordinary sandy areas. This means that if you are traveling, for example, in the desert, where there is often the same type of landscape without stones and vegetation, then at some point there is a chance that you will simply start to fall "under the ground".
Quicksand: what is it
Basically, quicksands are formed in places where underground sources appear or when groundwater approaches the soil. In addition, the condition for their appearance is the presence of sand without clay impurities with a grain diameter of up to 3 mm.
The smallest particles of moisture, mixing with such sand, do not allow air to pass through, and the friction between the grains of sand disappears. As a result, the grains of sand turn into a semi-liquid mass, a swamp, which outwardly is almost impossible to distinguish from an ordinary desert or beach. It is a viscous mass with a huge reaction force.
How to spot quicksand
Visually detecting classic quicksand is difficult - they can lie in wait for a traveler anywhere along the entire path. There is a road that takes more than one day, gradually mindfulness becomes dull, which leads to serious consequences.
Since quicksand is a viscous quagmire, outwardly it looks like a flat surface with small motionless ripples. That is, any flat territory can potentially turn out to be an impassable swamp. It should be noted that sand can dry out on the surface of the bog and sometimes even grass grows on it.
Most often, quicksand can be found along the banks of reservoirs and in the lowlands of hills - where underground sources are likely to come to the surface. To make sure, you need to move slowly, be able to quickly get rid of the backpack and other cargo, as well as feel the road in front of you with a pole or stick.
In a normal, dry state, when pouring from vessel to vessel (let's take an hourglass as an example), sand passes air. But if there is moisture between the grains of sand, the air does not pass, and the sand does not spill out, clogging the passage. This property is the basis for the appearance of a quagmire.
Such a sandy is characterized by a huge counterforce. If a person's leg falls into quicksand, it is necessary to expend the effort of a heavyweight weightlifter to free it, and then, provided that his second leg has a reliable fulcrum and is on a solid surface.
In addition, the impact of a quagmire can be compared to a seat belt - the faster the trapped person moves, the stronger the swamp binds him. This is due to the momentary "solidification" of quicksand due to the appearance of rarefied air under the released foot. The presence of a discharged space leads to the opposite effect - tightening the leg even deeper ("collapse").
Quicksand vs. Man
At its core, quicksand can be attributed to a variety of non-Newtonian fluids with a high content of fine solids (grains of sand). That is why a person, getting into such a place, begins to fall into it, like into water. If at the same time he does not make sudden movements, then the dive will stop when the mass of the displaced sand becomes equal to the mass of a person.
What to do if you get caught in quicksand
Exist certain rules behavior when hit in quicksand. Following these rules will allow you to get out of the situation alive.
1. Don't panic! If you start to twitch or make other sudden movements, you will go towards the core of the planet.
2. Fall on your back, flat, preferably on your back - in general, take a horizontal position with your whole body.
3. Try to immediately throw off everything superfluous - a backpack, a tent, etc. Life is more important.
If you start making sudden movements, pits will appear that will continue to suck. After the excitement has calmed down, move slowly, preferably back, in the direction from which you came, since it is not known how far the dangerous sands extend.
Relax your body, imagine that you are lying on your back in the water and relaxing. When moving, the sand should flow gently under the body and on the sides. This process is laborious, but effective. If Bottom part your body will still enter the sand vertically, put your torso on the surface and slowly, but with effort, gradually release your legs.
Interesting and tragic facts about quicksand
Morecambe Bay, England. Known since the 15th century, when it was forbidden to enter the sand at high tide. Annually claimed the lives of up to 150 people. People who fell into quicksand died during a 9-meter high tide that covered them with their heads.
Goodwin Shoals at South Foreland, England. Devour the ships, the remains of which rise above the sands. The place is known as the "Ship Graveyard". One day, the Goodwin Shoals swallowed up the lighthouse tower.
Tarnagen Fjord, Alaska. The coast is about 80 km long and consists of quicksand.
Sable Island, Atlantic. Quicksand swallows entire ships after shipwrecks.
Jamaica, city of Port Royal. Completely drowned in quicksand in 1692. 2000 citizens died. After the earthquake, the soil hardened, so it was initially believed that the city was swallowed up by the “abyss of the sea”.
An example of hitting the quicksand of American paratroopers
The phenomenon of quicksand in most people is associated with terrible pictures of a person being pulled deep into the abyss.
Many see mysticism in this, tie the influence of cosmic or otherworldly forces. But how does everything really happen and is quicksand really so dangerous? How are they formed and how not to become a victim of this natural phenomenon?
Physical explanation and types of quicksand
The depth of quicksand can reach several meters, and may be only a few centimeters. From the point of view of physics, the explanation for quicksand is very simple and depends on the ratio and interaction of sand and water.
Sand grains are enveloped in water, and a film forms around them. There is air between the grains of sand, but with an increase in the amount of water, the air is displaced, and a mixture of sand and water is formed, the properties of which differ significantly from the mixture of sand, water and air.
There are two types of these sands:
1. With a wet surface. They are found on the shores of lakes, rivers, seas, where rising springs often come across. On top there may be a thin crust of silt formed from a fine fraction of sand.
2. With a dry surface. Found in deserts and rocky areas.
The reason is the source of water
A prerequisite for the formation of quicksand is a large source of water, which is located at a depth of several meters, and sometimes several tens of meters.
These springs provoke shedding of sand. In most cases, they try to break out with great force, rising as close to the surface as possible and enveloping individual grains of sand with water.
Thus, a loose sandy mass impregnated with water is formed, which for some time retains its balance. When any object hits here, the structure collapses, and physical forces try to push back the displaced sand.
Suction occurs. The question arises: can any source of water cause quicksand? Such a source can be one that moves in an inclined horizontal direction or almost in a vertical direction.
It is sometimes impossible to determine the location of such sand. From above, it looks quite reliable and there is no doubt whether it is possible to move on such a surface. Grass and flowers can grow here, however, if there is a similar sand formation in a rocky area, it is better to bypass it.
It is simply impossible to check whether a nearby source of water provoked the appearance of quicksand.
Is it possible to get out?
Statistics show that tragic incidents involving falling into quicksand are very common. Why is it so difficult or almost impossible to get out of the whirlpool of sand?
The fact is that it is very viscous, so any sudden movements cause even more resistance, despite the fact that the density of quicksand is only one and a half times greater than the density of water.
You can get out of the elements only if you move very smoothly, or even better, try to lie on your back, freeing your legs, and thus, as it were, float on the sand. In this case, you can keep the balance certain time and wait for the rescuers to arrive.
In response to the sharpness, the sand mass seems to harden. Independent attempts to pull out, for example, a leg form a rarefaction of air. There is a huge force pulling the leg back. The effort required to lift a leg can be compared to the weight of a car.
In dry sand, everything is different: a person buried even up to his neck can gradually get out of it on his own, because when moving slowly, air first enters the free space, and then grains of sand fill the niche. In quicksand, there is no such air, and the suspension is comparable in consistency to jelly, and the slowly moving mass does not have time to fill the resulting cavity, forming a vacuum.
Other causes
Quicksand occurs most often not in deserts, as many people think, but in rocky areas and in areas of frequent tides. A well-known area with dangerous tides is the Bay of Morecambe, in particular the city of Arnside, located in England. At low tide, the bottom quickly dries up and becomes a trap.
The tide rises ten meters and covers everything that is in the zone of quicksand.
Another reason for the appearance of quicksand can be static charges arising from the mutual friction of sand grains. Since they are all charged in the same way, the cohesion is weakened and the surface becomes unstable. Quicksand is found in Canada, on the islands Caribbean, in England. There is a place in Alaska where the territory with treacherous sands stretches for 80 km, and not far from here there is a special rescue service in case someone falls into the trap of nature.
There are many more places on the planet that are better not to fall into accidentally. And one has to be very careful when going there. Quicksand is a good example of such places. There are many chilling stories about them. According to some legends, there are sands that can swallow a person completely in a few minutes (the sand dunes between North and South Wales have such a reputation). However, in order to perish, a lone traveler in desert places does not have to be dragged with his head. One day, a married couple went to private car(SUV, by the way) on a seemingly safe sandbank at high tide. The wheels immediately sank into the sand. The woman who got out of the car also fell knee-deep, where her feet seemed to be squeezed by an iron grip. The husband could not save his wife - the ocean quickly hid her from her head.Researchers have repeatedly taken up the study of the phenomenon of quicksand, and gradually the situation with them has become more or less clear. Undoubtedly, the properties of wet sand depend significantly on the amount of water it contains. Wet sand grains easily stick together, showing a sharp increase in cohesive forces, which in dry sand are due only to surface irregularities and therefore are very small.
The surface tension forces of the water films surrounding each grain of sand cause them to stick together. In order for the grains of sand to stick together well, water must cover the particles and their groups with a thin film, while most of the space between them must remain filled with air. If the amount of water in the sand is increased, then as soon as the entire space between the grains of sand is filled with water, the surface tension forces disappear and a mixture of sand and water is obtained, which has completely different properties. Thus, quicksand is the most common sand, under the thickness of which, at a depth of several meters, there is a fairly strong source of water.
Quicksand is most commonly found in hilly or tidal areas. Moving from the mountains, the streams of water move through channels carved inside the dolomite and limestone rocks. Somewhere it breaks through a stone and rushes up in a powerful stream. If a layer of sand is encountered along the way, then the stream of water coming from below can turn it into quicksand. The sun dries the top layer of sand, and a thin hard crust forms on it, on which grass can even grow. The illusion of well-being and tranquility will instantly evaporate, as soon as you step on it, the soil will float from under your feet.
Why do people fall into quicksand? The point is the resulting structure of the arrangement of grains of sand. A stream of water coming from below whips up a loose pillow of grains of sand, which is in relative equilibrium for some time. The weight of a traveler wandering into such a place brings down the structure.
The grains of sand, being redistributed, move along with the body of the victim, additionally, as if sucking the poor fellow into the soil layer. After that, the structure of the sand around the unfortunate person becomes completely different - tightly pressed wet grains of sand form a trap due to the surface tension of the water layer. When you try to pull your leg out, a rarefaction of air is formed, pulling the leg back with great force. The force required to lift the leg in such a situation is comparable to the weight of the car. If the sand were dry, then with slow movement, the air that was between the grains of sand would first come to the vacant place, and then the sand itself, crumbling, would fill the gap. Buried even up to the neck in ordinary sand, a person may well get out of it on his own (anticipating objections, let me remind you that in the White Sun of the Desert the hero was previously bound). In quicksand, a viscosity comparable to thick jelly will not allow this to be done.
The density of quicksand is about 1.6 times that of water, but this does not make it possible to swim in it. Due to the high humidity, the sand is viscous, and any attempt to move in it is met with strong opposition. The slowly flowing sandy mass does not have time to fill the cavity that appears behind the shifted object, and rarefaction, a vacuum, arises in it. The force of atmospheric pressure tends to return the object to its original place - it seems that the sand "sucks" its victim. Thus, moving in quicksand is possible, but only extremely slowly and smoothly, since the mixture of water and sand is inertial in relation to fast movements: in response to a sharp movement, it seems to harden.
For the formation of quicksand, the movement of water from the bottom up is necessary - which provides a tide or underground flow. In the Sahara desert, quicksands are formed in the zone of the existence of a large underground river, which people did not know about until the beginning of the era of sounding the structure of the earth's surface from a satellite. Sometimes, an earthquake can be the cause of such a zone. Or human activity. One day, while trying to drain the construction area of the foundation of a high-rise building, a huge pump sucking water through a well went underground. Quicksand is often encountered by builders of buildings and the subway in St. Petersburg, where soils are oversaturated with water. In these places they are called quicksand.
Quicksand victims are not only lone travelers or animals. There is a place where ships are swallowed up by the sands: the South Foreland in England (the Goodwin Shoals) is world-famous as the “ship graveyard”. On a long shallow, there are wrecks of ships immersed in the sand. The sands tenaciously hold the victim, and it is almost impossible to save the ship, and sometimes the crew. Once the ship "Gelena Modjeska" became a victim of the Goodwin Sands, the cargo of which was estimated at 3 million dollars. For four days, eight rescue tugs tried to save the steamer, but on the fifth day, the Helena Modjeska broke in half, and the cargo and the ship perished in the sands. And in 1954, in this place, quicksand sucked in a whole lighthouse that warned ships of danger. The tower went into the sand completely.