The Beaches Are Moving

3 Pages 772 Words

The North Carolina barrier islands are a major part of the North Carolina coast. Here, the only constant is change. Dunes get blown around, beaches shrink and grow, and islands move landward. The recreational beach is like the “tip of an iceberg” stretching from the first dunes to an ocean depth of about 30 feet. That’s about one mile out to sea. The weather plays a huge role in the way sand gets moved and distributed. In fair weather the net movement of sand is onshore. Underwater sandbars work their way up the incline towards the recreational beach and sand is deposited there. In stormy weather the net movement of sand is offshore. Battering waves erode sand and bring it out to sea, flattening the beach. Sand cliffs and beach scarps are a sure sign of erosion. This beach/storm response is a mechanism for survival. “A way to bend without breaking,” said host and geologist Orrin H. Pilkey.
Ocean waves strike the beach at an angle. This is called long shore movement. The net flow of sand by the long shore movement in North Carolina is north to south and it transports about 100,000 cubic yards of sand per year. This plays a vital role in shaping the barrier islands.
Inlets are waterways that separate barrier islands and are important for the storage and transport of sand. Tides capture the long shore current sands and store them in two web-shaped deltas: The flood delta on the sound side, and the ebb delta on the ocean side. These deltas are constantly shifting.
15,000 years ago glaciers were beginning to melt and the sea-level rose. Before this there were maritime forests that extended forty miles out to the continental shelf. As the sea level rose islands formed and as sea level rose more the islands began rolling over themselves to keep up with the receding mainland. Barrier islands still do this today, that is how sound dwelling oyster shells thousands of years old are found on the ocean side of i...