One explanation for the sounds is that the grains of these sands are all the same size and shape. When slightly damp, with a film of moisture surrounding each grain, the sand is set into uniform vibration. Sands are loose fragments of minerals or rocks. They are formed by the abrasion or breakdown of rocks through the action of water, ice, or air. Sand accumulates in areas where sediments are transported and deposited, such as in desert and beach environments.
Dry sand is blown by the wind.
Rocks, stumps, or shrubs will stop some of it, forming little mounds. In time the mounds may grow into sand dunes. Unless they become covered by vegetation, dunes usually migrate. Their movement is caused by the slow shifting of sand from the windward to the leeward side of the dune. Sand also occurs in alluvial fans, which are fan-shaped, sedimentary deposits at the mouths of mountain canyons.