Quicksand: what is the natural phenomenon?

Walking somewhere in the countryside, enjoying the charm of flowering plants, listening to birds whistling funny songs, you can accidentally be trapped in a quicksand. But immediately you should warn that it's not so scary, as shown in some films of the genre "horror." Yes, of course, they should be avoided, but at the same time do not be afraid. There are several consistent rules, knowledge of which will avoid such situations.

What is quicksand? This is really an interesting natural phenomenon, but no kind of soil type. A mixture consisting of fine-grained material, clay and water (in deserted places - a mixture of sand and air). It looks solid, but becomes unstable when there is pressure on its surface. It is formed when water supersaturates such soil. The usual, natural origin of sand (quarry, mountain, sea) consists of tightly packed grains forming a stiff mass (approximately 25 to 30 percent of the space between grains is filled with water or air). Since many grains of sand have an elongated shape, their separation can occur, and then the voids will form 30 to 70 percent of the mass. This mechanism is similar to a house of cards when the space between the cards is much larger than the space occupied by them. The liquid contributes to the creation of a liquefied soil, which is unable to withstand the weight load.

Shifting sands can form in standing and flowing waters, flowing upwards (as in artesian sources). Water jets directed upwards resist the force of gravity and inhibit the soil particles. Saturated precipitation may look quite solid, but a slight mechanical stress on their surface initiates liquefaction. This leads to the fact that the sand is formed into a slurry and loses its force. Because of amorphous water, quicksand, liquefied sediments, spongy, fluidlike, soil texture are formed. Objects falling into such an environment are lowered to a level at which their weight is equal to the weight of the displaced mixture (from soil and water). Liquefaction is a special case of the phenomenon under consideration. So, in the case of an earthquake, pore pressure in shallow groundwaters immediately increases . Wet liquefied soil loses its strength, which leads to the collapse of buildings and other objects located on its surface.

Shifting sands form where natural springs exist, in swampy or damp places, near rivers, on beaches, although they are often not easily identified. If you suddenly fall into them, then they retreat quickly and gently, reacting with an interval of a couple of seconds. They are a non-Newtonian fluid, that is, at rest they represent a solid (gel-like), but the slightest effect on them causes a sharp decrease in viscosity. In the deserts, they also occur, but extremely rarely, where sand deposits occur, for example, on the leeward side of the dunes. But the reduction is limited to a few centimeters, because once the air in the voids between the sand grains is removed (and this happens quickly), they are again condensed.