What is quicksand?

You find quicksand in places where there’s water flowing underneath sand.

People used to think that quicksand was a certain kind of sand – that the grains had to be round and smooth like little ball bearings. But grains of quicksand can be big or little, rough or smooth. You can even have quicksand made of gravel. You find quicksand in places where there’s water flowing underneath sand. The water pushes up with just the right pressure to equal, or slightly more than equal, the sand’s weight. Then each sand grain has a cushion of water around it – and that’s quicksand.

The fact is that most people can float on quicksand. It actually holds you up better than water. If you ever find yourself stuck in quicksand, try not to panic. Try gently falling backward spread-eagled. You may eventually have to roll or swim – very slowly – to solid ground.

Anything that won’t float in water isn’t likely to float in quicksand either. About a century ago, an entire train in the Kansas Pacific Railroad line plunged into quicksand. Workers later pulled out most of the cars, but they never did find the engine.

EarthSky