Carolina Environmental Diversity Explorations

Small sand volume barrier islands · By Dirk Frankenberg

beach and berm of Masonboro Island

Figure 2. Another view of Masonboro Island. (Photograph by the author. More about the photograph)

Figure 2 shows another view of the same rather dull topography of beach and berm. A little life can be seen in the middle background where pioneering sand dune plants have established a precarious roothold. In the left background you can see where sand has been washed over the berm and into the salt marsh beyond. This is a common occurrence during storms and is called a washover event by coastal geologists. The one you see here was created during Hurricane Floyd. Overwash events are one of the natural processes by which sand moves landward during periods of rising sea level. This landward transport maintains the existence of the barrier island, although not in exactly the same place geographically. The slight change of location is not a problem on an undeveloped island like Masonboro, but as you will see, it can be a problem when the island overwashes out from under beachfront houses and roads.

Definitions

topography n.
The surface features of a place or region; the character, natural features, and configuration of land; terrain.
berm n.
A terrace formed by wave action along the backshore of a beach.
dune n.
A hill or ridge of wind-blown sand.
precarious adj.
Dangerously lacking in security or stability; subject to chance or unknown conditions; lacking stability; insecure, shaky, tottering, unstable, unsteady, unsure, weak, wobbly.
salt marsh n.
A low coastal grassland frequently overflowed by the tide.
washover event n.
Accumulation of sand on the landward side of a barrier island that is deposited by storm waves which overtop the island.
barrier island n.
A long, relatively narrow island running parallel to the mainland, built up by the action of waves and currents and serving to protect the coast from erosion by surf and tidal surges.