Outforia Quicktake: Key Takeaways
- Quicksand is a colloid, a mixture of microscopic particles dispersed in a fluid, usually water. It’s formed in areas with fine sediment like sand or silt and occurs when water or air creates large voids in the sand.
- It’s most often found near upwardly moving water, mouths of large rivers, pools of water where drainage is reduced, and areas hit by earthquakes. Deserts are not frequent locations for quicksand.
- Dry quicksand, which forms after sandstorms in deserts, is more dangerous than wet quicksand, behaving like snow in an avalanche.
- Quicksand is a non-Newtonian fluid, behaving like a solid at rest and like a liquid when agitated.
- Areas with a high likelihood of quicksand include Tasmania, the UK, France, Sweden, and the US.
Picture this: an adventurer venturing into the unknown, the ground suddenly shifting beneath their feet as they sink into a perilous trap. Quicksand.
It’s the stuff of movies and childhood tales, but is it real? Where is quicksand found, and how can you find it?
Quicksand is found in areas where there is fine sediment, like sand or silt. When mixed with water or air, this creates gaps, called voids, in the sand.
Movement caused by people, earthquakes, or vibrations turns the quicksand from a solid to a liquid very quickly.
What Is Quicksand?
Quicksand is sand that has larger than normal gaps between the grains. It looks normal and safe to step on, but it is not. These gaps are called voids.
Sand normally has voids that make up 25 to 30% of its mass. In quicksand, these voids comprise from 30 to 70% of the mass of the sand.
This means that if the sand is agitated—by movement, upward motion of water, or vibration—the fragile structure collapses and becomes fluid.
All that’s holding the sand grains together is friction, and when movement destabilizes the sand grains, quicksand is the result.
Quicksand is a colloid. A colloid is a mixture of microscopic particles dispersed in a fluid, usually water. These particles can be sand, silt, mud, or even grain.
Colloids don’t follow the normal laws of physics. At rest, they behave like solids. When force is applied, they behave like liquid.
Other examples of colloids can be found around your home. Toothpaste and hair gel are colloids. When you squeeze a tube of toothpaste, the mixture behaves like a liquid as you force it out of the tube.
Where Is Quicksand Found?
Quicksand is most often found in:
- Near upwardly moving water, such as underground springs. Springs that rise up in sand on beaches and riverbanks at low tide can cause quicksand.
- At the mouths of large rivers.
- In pools of water where drainage is reduced by an underlying layer of non-permeable material, like clay.
- Areas hit by earthquakes
Despite what cartoons might have you thinking, deserts are not likely places to find quicksand. Sometimes there are large air gaps in desert sand, but this isn’t common.
After a sandstorm, you are most likely to encounter desert quicksand. This is known as “dry quicksand.”
The Danger of Dry Quicksand
Dry quicksand is much more dangerous than wet quicksand.
This is because it behaves in much the same way that snow in an avalanche does. Once the dry sand or other grains solidify again around you, they can restrict air flow to your lungs. These grains don’t even need to be sand to have this effect.
This is what happened to a man who fell into a grain silo in Germany in 2002. It took a while for firefighters to figure out which of the eight silos he was in. By then, he had sunk up to his chest in the grain.
Every time he let out a breath, more grain would fill the gap. This made it harder and harder for him to breathe.
Firefighters saved the man with a clever solution. They gave him oxygen. They then lowered a cylinder over him, which also sank.
They sucked out the grain inside the cylinder with an industrial vacuum. The cylinder stopped more grains from falling around the man.
What Is Dry Quicksand?
Dry quicksand is sand with voids made of air gaps instead of water. It can be very dangerous, as air is less dense than the human body, so you keep sinking. Thankfully, it is fairly rare.
Movies such as “Lawrence of Arabia” show entire vehicles swallowed by dry quicksand in the desert.
Professor Detlef Lohse and his fellow researchers from the University of Twente (Netherlands) did some experiments to find out how dry quicksand behaves.
- The team used very fine-grain sand in a container.
- They blew air into the sand from underneath the container.
- When the sand settled, it had a packing volume of just 41%.
- They used a 4cm ping pong ball, which they filled with various bronze ball weights to vary its weight.
- They hung the ping pong ball on a thin rope, just touching the surface.
- They burned through the rope.
The result? The ping pong ball moved downward through the dry quicksand. It soon completely disappeared beneath the surface. This shows just how dangerous dry quicksand can be.
What Happens When You Fall In Quicksand?
When you fall into quicksand, your weight and movement cause the fragile bonds between the grains to fall apart. You are creating physical stress. This turns sand full of voids (gaps) from a solid into a liquid.
Just a 1% change in weight can cause the viscosity of the quicksand to drop by a factor of 1 million.
You sink fast at first, as your heavy legs going downward have a small surface area but a lot of weight. As you sink further down, the sand becomes more viscous. This is due to the formation of sand sediment.
This makes it hard to escape. It is like moving through setting concrete.
Luckily, the density of the water in the sand is higher than that of your body, so you will not completely sink under the surface of the quicksand.
Watch the video below to know more about what will happen if you fall into a quicksand.
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Why Can’t Signs Be Put Up Warning of Quicksand Areas?
There are many areas susceptible to quicksand where warning signs are present. However, there are equally as many without warning signs.
This is because quicksand patches don’t stay in the same location. They move every time the tides change. This makes quicksand areas almost impossible to predict.
This hazard sign is at Paxton Pits in Cambridgeshire, UK. Due to high rainfall and flooding, the UK is one of the world’s quicksand hotspots.
World Quicksand Hotspots
Here are the places worldwide where you are most likely to run into quicksand: Quite literally speaking.
- Pieman Heads and Arthur River, West Coast, Tazmania: Between the Arthur River and the Heads is an area notorious for quicksand. This is where the river flows into the sea.
- Trelleborg Beach, Sweden: This beach is 40 km long, and there are no signs showing dangerous quicksand areas. This is because quicksand patches move depending on tides. The high rainfall makes quicksand more likely.
- Near St Osyth, Essex, UK: A storm broke up the sand dunes near St Osyth, and heavy rain plus high tides created many areas of quicksand.
- Santa Ana River, US: The silty, fine sand of the area slips easily into the quicksand state. Floods in the area make the problem worse.
- Mont St. Michel, France: This famous landmark in Normandy, France, is only reachable by a land bridge that appears at low tide. Tourists often play in the quicksand caused by the tides. While it’s fun in a crowd, it’s not advisable to try this alone.
- Broomway Trail, near River Thames, UK: This notorious path leads out to sea at low tide. There are also unexploded munitions under the sand.
Check out this video for more dangerous areas of quicksand.
Quicksand Fun Facts
Check out these interesting quicksand facts below.
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What type of sand is quicksand?
Quicksand can be any type of sand. What makes it quicksand are the voids between the grains.
Quicksand has voids that comprise 30% to 70% of its mass. However, the addition of clay particles and salt can create an especially sticky quicksand that is even harder to get out of.
How do you spot quicksand on the beach?
Quicksand can look just like normal sand. Avoid areas where rivers meet the sea or where underground springs rise. Tidal mudflats, swamps, and marshes are also hotspots.
When pressed, quicksand will release water. Check for puddles. Unusual ripple patterns can indicate an area of quicksand.
Where are there the most areas of quicksand?
Quicksand can be found anywhere in the world where there are fine particles and water. Hotspots include Tasmania, the UK, France, Sweden, and the US. Areas with high rainfall and floods or storms are more likely to have quicksand.
Can earthquakes cause quicksand?
Earthquakes can cause quicksand as they create ground vibration. This breaks up the bonds between sand grains. This is a major challenge for civil engineers.
Many buildings sank in the 1964 Niigata earthquake in Japan. This happened in the 1989 Loma Prieta, California, earthquake too. In engineering terms, this is known as soil liquefaction.
How fast do you sink in quicksand?
National Geographic Channel broadcaster Johnny Philipps sank up to his waist in quicksand in 8 minutes. Much depends on what position you fell in and how much the sand was agitated.
Does salt make quicksand more dangerous?
Daniel Bonn of the University of Amsterdam found that adding salt to the sand mixture created a stickier layer that would trap a person more efficiently.
Quicksand without salt didn’t create such a viscous bottom layer. You can get freshwater quicksand without salt, though.