If you do step into quicksand, says study co-author Daniel Bonn, you'll only sink in a little deeper than your waist. The authors estimate that the force needed for someone to pull their foot out of quicksand at a speed of a centimeter a second would be the equivalent of that required to lift a medium-size car. Water has to be introduced into the sand sediment to loosen it, and this requires considerable amounts of force. It's the difficulty of moving this dense sand that causes the problem.

The increase is due to the formation of sand sediment, which has a very high viscosity. Difficult to Get Out Ofīut if quicksand becomes less viscous as you struggle, why is it so difficult to escape? The reason, explain the study's authors, is that after its initial liquefaction, quicksand's apparent viscosity (thickness or flow resistance) increases. But when they shook the container a bit harder, the ball descended to the bottom. When they shook it only a little, the bead stayed floating on top. At rest, the bead remained on the surface, despite aluminum's higher density.īut then scientists started shaking the container. But a piece of aluminum will float on top of quicksand until motion causes the sand to liquefy.ĭuring their study, researchers placed an aluminum bead on top of a container of laboratory-created quicksand. Aluminum, for example, has a density of about 2.7 grams per milliliter. You would descend about up to your waist, but you'd go no further.Įven objects with a higher density than quicksand will float on it-until they move. At that level of density, sinking in quicksand is impossible. But human density is only about 1 gram per milliliter. Quicksand has a density of about 2 grams per milliliter. The reason is that humans just aren't dense enough. This causes a trapped body to sink when it starts to move.īut a person moving around in quicksand will never go all the way under. At rest, quicksand thickens with time, but it remains very sensitive to small variations in stress.Īt higher stresses, quicksand liquefies very quickly, and the higher the stress the more fluid it becomes.

Researchers in the Netherlands and France studied quicksand, a combination of fine sand, clay, and salt water.

Real quicksand is certainly hard to get out of, but it doesn't suck people under the way it always seems to in the movies.Īccording to a study published in the current issue of the journal Nature, it is impossible for a person immersed in quicksand to be drawn completely under. You won't sink in-at least not all the way. If stumbling into quicksand ranks on your list of worries, don't panic.

Raven stuck in quicksand