STRANGE Sand Acts Like Liquid

This is a good example of how quicksand works, only with water as the working fluid. Place your hand in while operating then turn off the air and your hand is trapped proportional to the volume of sand above it. This is what makes quicksand so dangerous as your body blocks the fluid flow that keeps the sand suspended, the sand settles around you, solidifies and tends to cause you to sink as your combined particle density is too great to float. If deep enough the result is not good.
 This is also how an avalanche works. Once the snow starts moving it is suspended in a sort of cloud of snow and entrained air. If the speed is great enough, and it doesn't take much, you will be carried along within the cloud until it stops. At that point the snow settles into a mass again and if you happen to not be at the surface, and because of your density compared to the cloud you probably won't be, well you can guess the result. If you didn't impact something on your trip you will suffocate from either the weight preventing you from breathing or CO2 accumulation.
 Check out this one from Mark Rober https://www.youtube.com/watch?v=My4RA5I0FKs&feature=em-uploademail