A sand dune is a very large accumulation of loose sand, often forming "wave" shapes. High winds carry sand for long distances and pile it up.
(A similar process occurs with blowing snow that forms drifts in blizzards.)
A loose pile of wind-blown sand.
A sand dune
Dune - Dune album - was created in 1995.
A desert dune is a dune formed in a desert
The secondary dune is the sand dune behind the primary dune.
crescentic dune linear dune star dune dome dune parabolic dune
the top of a sand dune is called the crest of the dune.
This is a dune formed from salt.
The sand dune eroded during the storm. We had a picnic on the dune above the beach.
dune line
A dune beginning to exist or appear.
A dune will disintegrate.