Quicksand is a mixture of sand and water, or sand and air, that looks solid, but becomes unstable when disturbed by any additional stress. In normal sand, grains are packed tightly together to form a rigid mass, with about 25 to 30 percent of the space voids between the grains filled with air or water. Because many sand grains are elongate rather than spherical, loose packing of the grains can produce sand in which voids make up 30 to 70 percent of the mass.
This arrangement is similar to a house of cards in that the space between the cards is significantly greater than the space occupied by the cards. The sand collapses, or becomes 'quick,' when additional force from loading, vibration or the upward migration of water overcomes the friction holding the grains together.
Most quicksand occurs in settings where there are natural springs, either at the base of alluvial fans cone-shaped bodies of sand and gravel formed by rivers flowing from mountains , along riverbanks or on beaches at low tide. But then the water and sand separate, leaving a layer of densely packed wet sand which can trap it.
It is true that struggling can make you sink in further, but would you actually sink far enough to drown? Daniel Bonn from the University of Amsterdam was in Iran when he saw signs by a lake warning visitors of the dangers of quicksand. He took a small sample back to his lab, analysed the proportions of clay, salt water and sand, and then recreated quicksand for his experiment. Instead of people, he used aluminium beads which have the same density as a human.
He put them on top of the sand and then, to simulate the flailing of a panicking human, he shook the whole model and waited to see what happened. The answer was no. At first they sunk a little, but as the sand gradually began to mix with water again, the buoyancy of the mixture increases and they floated back up to the top.
Bonn and his team tried placing all sorts of objects on his lab-made quicksand. If they were of density equivalent to a human they did sink, but never completely, only half way. This is really when quicksand can be dangerous. If you stop after the first step, the sand particles beneath you get compressed by your weight. The sand around you also settles into place. Continued movement like thrashing around from panic keeps the mixture more like a liquid , so you sink further.
However, the average human has a density of about 1 gram per milliliter, while the average quicksand density is about 2 grams per milliliter. You'll only sink halfway, no matter how badly you freak out. Disturbing quicksand makes it flow like a liquid, but gravity acts against you.
The trick to escaping the trap is to move slowly and try to float. Strong forces stiffen quicksand, making it more like a solid than a liquid, so pulling and jerking only make a bad situation worse. A quick Google search reveals most writers don't have personal experience with quicksand or consult water rescue experts.
Quicksand can kill! It's true you don't sink in quicksand until you're submerged. Humans and animals typically float in water, so if you are standing upright, the furthest you'll sink in the quicksand is waist-deep. If the quicksand is near a river or coastal area, you can still drown the old-fashioned way when the tide comes in, but you won't suffocate with a mouthful of sand or mud.
Dry quicksand presents its own special risks. There are reports of people, vehicles, and entire caravans sinking into it and being lost.
Whether this has actually occurred is unknown, but modern science considers it possible. In the movies, escape from quicksand often comes in the form of an outstretched hand, underwater vine, or overhanging branch. The truth is, pulling a person even yourself out of quicksand won't result in freedom.
Removing just your foot from quicksand at the rate of 0. The harder you pull on a branch or a rescuer pulls on you, the worse it gets! Quicksand is no joke and self-rescue isn't always possible.
If you step into quicksand, you should:. You don't need to visit a riverbank, beach, or desert to explore the properties of quicksand. While quicksand can occur in almost any location where water is present, there are certain locations where it's more prevalent. Places where quicksand is most likely to occur include:. The next time you're at the beach , notice the difference in the sand as you stand on different parts of the beach that have varying levels of moisture.
If you stand on the driest part of the beach, the sand holds you up just fine. The friction between the sand particles creates a stable surface to stand on. If you move closer to the water, you'll notice that the sand that is moderately wet is even more tightly packed than the dry sand. A moderate amount of water creates the capillary attraction that allows sand particles to clump together.
This is what allows you to build sand castles. But beach sand could easily become quicksand if enough water were thrust up through it. If an excessive amount of water flows through the sand, it forces the sand particles apart. This separation of particles causes the ground to loosen, and any mass on the sand will begin to sink through it. In the next section, you will find out how to save yourself if you happen to fall into a pit of quicksand. The more you struggle in quicksand the faster you will sink.
If you ever find yourself in a pit of quicksand, don't worry -- it's not going to swallow you whole, and it's not as hard to escape from as you might think. The human body has a density of The key is to not panic. Most people who drown in quicksand, or any liquid for that matter, are usually those who panic and begin flailing their arms and legs.
It may be possible to drown in quicksand if you were to fall in over your head and couldn't get your head back above the surface, although it's rare for quicksand to be that deep.
Most likely, if you fall in, you will float to the surface. However, the sand-to-water ratio of quicksand can vary, causing some quicksand to be less buoyant.
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