Sand Avalanche

sand avalanche : Movement of large masses of sand down a dune face when the angle of repose is exceeded or when the dune is disturbed.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003


A fortnight ago friends and I were at Eureka sand dunes near Death Valley. We had an awesome time climbing up the structure made up of innumerable ridges and valleys. To climb up, you have to walk on edge of a ridge, which usually gives way to a deep crest on either side. One side of the ridge is steeper that the other and the sand is a loose on this side.

Some places the ridges were so steep that the sand dune seemed unstable - as though a light wind or a slight earthquake tremor could bring the whole structure down. In certain places we could push a little sand down from the top and watch as a mini avalanche was created! We spent some time playing around and making sand rivers.

We heard trembling at a certain point on the dunes.. we thought the sound could be from an earthquake or a power station nearby. We dont know what what made the sound, but who knows.. it just might have been a sand avalanche!