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Table Mountain National Park management has issued a warning for locals and tourists thinking of taking a stroll along Noordhoek Beach to be on the lookout for quicksand near the shore.

Beachgoers are being advised by park authorities to be cautious and keep a safe distance of 15 to 20 metres from the lagoon, especially if they are riding horses.

The warning follows an incident in February where a local, Marilize Burger and her horse got stuck in quicksand during a leisurely ride along Noordhoek Beach. Burger then jumped off and immediately started sinking too.

Familiar with quicksand, Burger told The False Bay Echo, “Patches of quicksand normally appear almost glossy or shiny. These sections looked completely firm and even dry,”

“Bitou’s back legs started sinking, and despite my usual technique to ask him to move forward, he tried to jump out several times but couldn’t. I’ve never encountered the quicksand being this deep or more challenging than him sinking to his knees, making the situation quite severe.”

“I realised that I could crawl out, but because it was slightly uphill and he was already tired, he would struggle to get out a second time. I let go of the reins, slapped him on the neck and shouted ‘go go go’. He then launched out and proceeded to trot home to his stable.”

Similar conditions after the scary incident have now prompted authorities to issue the warning, although the odds of sinking entirely were pretty slim according to Dr Ryan Tucker, a senior lecturer in sedimentology and palaeontology at Stellenbosch University.

Dr Tucker says quicksand forms when granular materials such as sand, silt, or clay interact with water, and saturation between loose sand grains creates a soupy, liquefied substrate that lacks competency – so that anything applying weight would sink into it.

Despite a favourite way to kill off the bad guys in cowboy movies, it does not happen in real life. People and animals can get stuck in it, but they don’t get sucked down to the bottom – they float on the surface.

Our legs are pretty dense, so they may sink, but the torso contains the lungs, and thus is buoyant enough to stay out of trouble (Quicksand has a density of about 2 grams per cubic centimetre, whereas the density of the human body is only about 1 gram per cubic centimetre).

If you do find yourself stuck in quicksand, the best idea is to lean back so that the weight of your body is distributed over a wider area. Moving won’t cause you to sink. In fact, slow back-and-forth movements can actually let water into the cavity around a trapped limb, loosening the quicksand’s hold.

It won’t be easy though. Physicists have calculated that the force required to extract your foot from quicksand at a rate of one centimetre per second is roughly equal to the force needed to lift a medium-sized car.

So quicksand won’t kill you, but it’ll put a damper on your stroll, so best to keep an eye out on the beach.

[source:falsbayecho&britannica]