Quicksand

Quicksand is caused by a solution of soil and water that appears to be a solid but when pressure is applied, it liquifies and supports no weight. The way to escape from it is to lay flat as possible and try to reamin as close to the surface as possible. Just like in water, you can float your way out of it. See the related link for more information.

Basically, it forms when...

1. just the right amount of water is under a mass of a combination of sand and other material such as clay.
2. The water lubricates the sand particles while the clay prevents it from moving further underground.
   • twigs and leaves can gather on the surface, making it difficult to distinguish from the surrounding environment
   • kicking is the worst thing you can do if your ever stuck in quicksand since it shuffles the water around, making more space for you to fall through
   • as they've proven on mythbusters and on several other occasions, it is not possible to completely sink in quicksand due to it's viscosity and your buoyancy (assuming your not carrying a brick of lead or anything really heavy.)
3. This renderes the seemingly solid sand to remain stable until any significant pressure is applied (eg. a person), then it almost instantly goes into a semi-solid state that supports very little weight

Quicksand is a colloid hydrogel consisting of fine granular matter (such as sand or silt), clay, and salt water. In the name, as in that of quicksilver (mercury), "quick" does not mean "fast," but "living" (cf. the expression the quick and the dead).

Water circulation underground can focus in an area with the optimal mixture of fine sands and other materials such as clay. The water moves up and then down slowly in a convection-like manner throughout a column of sand, and the sand remains a generally solid mass. This lubricates the sand particles and renders them unable to support significant weight, since they move with little friction, behaving more like a liquid when exposed to stress. Since water does not usually go up to the surface of the sand, the sand on top appears solid, and can support leaves and other small debris, making quicksand difficult to distinguish from the surrounding environment.

How To eScApE?

Quicksand has a density of about 2 grams per milliliter. But human density is only about 1 gram per milliliter. At that level of density, sinking in quicksand is impossible. You would descend about up to your waist, but you'd go no further.

Even objects with a higher density than quicksand will float on it-until they move. Aluminum, for example, has a density of about 2.7 grams per milliliter. But a piece of aluminum will float on top of quicksand until motion causes the sand to liquefy.

During their study, researchers placed an aluminum bead on top of a container of laboratory-created quicksand. At rest, the bead remained on the surface, despite aluminum's higher density.

But then scientists started shaking the container. When they shook it only a little, the bead stayed floating on top. But when they shook the container a bit harder, the ball descended to the bottom.