Sand dunes

In physical geography, a dune is a mount of sand built by eolian (wind-related) processes. Bare dunes are subject to changing location and size based on their interaction with the wind. The "valley" or furrow between dunes is called a slack.

Some coastal areas have one or more sets of dunes running parallel to the shoreline straight inland from the beach. In most such cases the dunes are important in caring the land against potential ravages by storm waves from the sea. Although the most broadly distributed dunes are those associated with coastal regions, the largest complexes of dunes are found inland in dry regions and associated with ancient lake or sea beds.Dunes also form below the action of water flow (Alluvial processes), on sand or gravel beds of rivers, estuaries and the sea-bed.

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