Carolina Environmental Diversity Explorations

The northern Outer Banks · By Dirk Frankenberg and Blair Tormey

Overwash at Coquina Beach

Overwash at Coquina Beach

Figure 13. Breached during the Halloween storm of 1991, this gap in the primary palisade dune at Coquina Beach has been the site of frequent overwash. (Photograph by Blair Tormey. More about the photograph)

During the Halloween Storm of 1991, the primary palisade dune at Coquina Beach was breached, causing extensive damage to the Park Service facilities. This overwash event filled the earlier bathhouse with sand and ripped up entire sections of what was once a loop road leading to the Coast Guard Station to the north. Ripped up blocks of asphalt still remain from the overwash, as well as a large, lobate, overwash fan deposit whose surface is about ten feet higher than the previous back-beach surface. After the storm, the beach access facilities were moved to their current location in keeping with National Park Service policies that require structures to be relocated if they cannot be reasonably protected and control measures are not required by law.

Figure 13 here shows the gap in the primary palisade dune at Coquina Beach. The dune originally extended from the dune behind the lifeguard chair to the dune on the left side of the picture.

Definitions

palisade dune n.
A dune that is natural or man-made that helps protect the shoreline from erosion, or helps prevent overwash.
dune n.
A hill or ridge of wind-blown sand.
overwash n.
The transport of sediment landward of the active beach by coastal flooding during a tsunami, hurricane, or other event with extreme waves.
lobate adj.
Having or resembling a lobe or lobes (a rounded projection that is part of a larger structure).
overwash fan n.
A break in a continuous dune line or line of vegetation where storm tides carried sand from oceanside, to estuaries, great ponds, and bayside; often clears a vegetation-free path from ocean to inner water body.
back-beach n.
The section of beach extending landward from the high water mark to the point where there is an abrupt change in slope or material; also referred to as the backshore.