To many, quicksand is just another word for mud. Rest assured, however, that this is certainly not the case. Far from it, in fact.
Unlike mud, which is really a generic term used anytime the ground gets wet and... muddy, quicksand carries with it a whole bevy of scientific words and phrases, as well as very technical definitions and explanations.
In other words, quicksand is mud, but it is also much more.
Quicksand, to use technical terms, is nothing but a hydrocolloid gel.
To explain: A colloid is a system wherein the particles of two different substances are interspersed with each other so as to form a single other substance. Adding the prefix 'hydro' simply means that the colloid is also mixed with water.
In the case of quicksand, the colloid generally consists of clay and another substance, such as sand or silt. And the water must be salt water.
This last fact hadn't actually been proven until September of 2005, so the science of quicksand is really a relatively new thing. How much remains a mystery about this substance is perhaps one of its most surprising features.
How it Works
When undisturbed, the hydrocolloidal mixture is actually somewhat solid, the entire entity having mixed itself into a single substance.
However, when pressure is applied to the surface of the substance (i.e. When it is accidentally stepped into) the water and the colloid actually separate, lessening the viscosity of the entire substance and causing you to quickly sink into it.
Almost immediately afterward, the viscosity suddenly increases once again as areas of high density form within the watery substance.
These high density areas would not be as likely to form if not for the presence of salt, which allows a process known as flocculation to occur, which is the combining of the colloids into a single substance once again.
Now what is left is a thick liquid with enough density to grab hold of any stray body parts that might have been unfortunate enough to land within its grasp.
The process of quicksand's actual transformation into a liquid is called liquifaction, a term often used in chemistry when a gas is forced into its liquid form, such as liquid nitrogen.
Now, once a person is stuck in the quicksand, things aren't nearly as bad as one might expect.
The human body actually has far less mass than the sand which is holding it down, so there really isn't much chance of being pulled under the surface, though struggling and flailing about can serve to dig a person in deeper. The trick to surviving quicksand is to stay calm.
In fact, with enough time and energy and lack of panic, it really shouldn't be too difficult to swim right out of the stuff.
Unfortunately, many quicksand beds are located in tidal areas near oceans, or beside rivers, so it’s a good idea to make sure to get out before the tide comes back in, lest drowning result.
And that, in short, is quicksand.
For an excellent demonstration on escaping quicksand, please see this video on youtube of Bear Grills teaching the proper technique.