Quicksand: geohazard tank model video

A video published on the BGS YouTube channel shows how quicksand conditions occur. Water is pumped in from the bottom of the model to simulate a spring, artesian condition or incoming tide, that may result in sand grains floating and quicksand to develop locally; the effect can be transient and change location rapidly. Quicksand develops when the sand grains can no longer remain in their original horizontal layers because the upward flow of water is sufficiently great to make the sand grains float. The sand is behaving as a fluid or quicksand. http://www.youtube.com/watch?v=19RAUY2z0pI