Why does wet sand turn into almost a liquid when it is shaken?

Question

So normally, wet sand usually is pretty solid, you can crumble it and other things, but when you shake it, it almost loses all its solid properties and flows. Why does this happen?

In: Geology

Answer 1

This is [what the atoms of a liquid do](https://en.wikipedia.org/wiki/Brownian_motion#/media/File:Brownianmotion5particles150frame.gif). That’s also kinda what the grains of sand do when you [blow air through the sand](https://www.youtube.com/watch?v=My4RA5I0FKs) or otherwise agitate.