Why is quicksand considered a solid and a liquid?

Basically, quicksand is non-Newtonian fluid. That means "the viscosity decrease under the strain and the friction" especially with certain temperature/pressure conditions. That's why more you resist more you sink into it. read more

Basically, quicksand is non-Newtonian fluid. That means "the viscosity decrease under the strain and the friction" especially with certain temperature/pressure conditions. That's why more you resist more you sink into it. So it acts like a liquid but looks like a gel consist of solid sand grains. read more

The Oobleck mixture isn't your typical liquid—or solid. The cornstarch-and-water mixture creates a fluid that acts more like quicksand than water: applying force (squeezing or tapping it) causes it to become thicker. read more

To understand quicksand, you have to understand the process of liquefaction. When soil liquefies, as with quicksand, it loses strength and behaves like a viscous liquid rather than a solid, according to the Utah Geological Survey. read more