Sand
It occurs when a piece of sand becomes so soaked that, instead of behaving like a solid, it acquires the properties of a viscous liquid. However, contrary to what Hollywood leads us to believe, this geographic accident does not suck adventurers into a terrible drowning. Of course, if you step in an area with quicksand, a person sinks. But if you stop struggling, it will float slowly. The human body is nearly half as dense as sand and water, and quicksand banks are usually not very deep. So, it’s pretty hard to sink all the way down, like in the movies.
Reader question – Abylene Dyane de Oliveira, Tarumã, SP
movie thing
The event is rare, but the recipe for it to happen is simple.
FIRM LAND
The friction between the grains is the force that sustains a body that rests on common and compact sand, such as beach sand, for example. When stepping on this type of soil, the weight of the body causes the surface grains to adjust, fitting together and making the soil firm.
SOFT SAND
Quicksand is nothing more than common sand subjected to an upward flow of water, coming from groundwater. The flow makes the ground neither hard enough to support the weight of a body nor liquid enough to swim in.
GETTING MIDDLED
This strange behavior of sand occurs because the liquid between the grains reduces the friction between them and the flow of water does not allow them to settle. That’s why, when supporting the weight on quicksand, the grains make way and the body sinks.
Emergency exit
The greatest danger is not sinking but getting stuck. see how to escape
1. Stop moving. The more you struggle, the more you open the way to sink. Pulling the legs up doesn’t help either, as the empty space created under the foot generates strong suction.
2. Increase contact with the surface by lifting your legs slowly. When you’re almost lying down on the sand, it’s time to crawl to the firm ground around the well.
3. Completely sinking is unlikely, but death can come anyway. In riverside regions it is possible to be trapped until the river level rises. In desert areas, one can die from starvation, hypothermia or long exposure to the sun.
Consultancy: Ideval Souza Costa, geologist at the Museum of Geosciences (IGc/USP)
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