Dunes are mounds or hills of sand which have been heaped up by wind action. Typically, dunes exhibit four distinct features, as listed below:
Primary Dunes - The first system of dunes shoreward of the water, having little or no vegetation, which are intolerant of unnatural disturbances.
Secondary Dunes - The second system of dunes shoreward from the water, with some vegetative cover.
Back Dunes - The system of dunes behind the secondary dunes, generally having vegetation and some top soil, and being more tolerant of development than the primary and secondary systems.
Troughs - The valleys between the dune systems.
The Importance of Dunes
Dunes are a natural levee and a final protection line against the sea. The destructive leveling of, or interference with the primary dune system (such as cutting through the dunes for access) can endanger upland areas by subjecting them to flooding from heavy wave action during severe storms and destroy a distinct and disappearing natural feature. Removal of sand from the beach and shore in dune areas starves dunes of their natural supply of sand and may cause their destruction from lack of sand. Appropriate vegetation can and should be encouraged throughout the entire system for stabilization. Check out the Use Activity Policies and Regulations for more information.