The Nature Of The Barrier Islands ~ by Thomas Yocum: Ecology and History of the NC Outer Banks and the Mainland

The islands of North Carolina's Outer Banks are the children of the sea. A series of low-slung sand islands stretching in a thin line from the Virginia border to Cape Lookout, they were born at the end of the last Ice Age when huge continental glaciers began to melt and the ocean began to rise. Since they formed ten thousand years ago, they have raced the rising waters westward, migrating as much as fifty miles to their present location.

The Outer Banks were formed by the force of moving water and moving water shapes them still. The islands were created when rivers and streams carrying silt- and sand-laden glacier meltwater flowed out into the ocean, creating deltas on either side of their main channels. These deposits grew as more silt and sand built up the upstream side. The ocean added sand as it washed over the top of the sandbar during high tides and storms. Steady winds blew sand that accumulated even more. A small, shallow lagoon began to form on the west side and a pair of young islands slowly rose out of the sea.

As they grew, prevailing ocean currents slowly ground away the face of the young islands, transporting sand particles down the line; increasing the material at one end as it robbed the same amount from the other. Gradually, the islands began to elongate, stretching into ribbons riding far out into the water. The island chain was broken in points by inlets, which allowed the water still flowing from mainland rivers to empty into the sea, but the island building process continued, with sand building up on the top of the islands while the ocean pulled away on the front of them.

This combination of replenishment and erosion has allowed the barrier islands to move as fast as they do for as far as they do. The vital supply of sand provided by the ocean overwash ensures the western side of the islands will be growing even as the eastern side is being washed away. The process is called island migration, and it's key to the survival of the barrier island chain.

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	The Nature Of The Barrier Islands by Thomas Yocum The islands of North Carolina's Outer Banks are the children of the sea. A series of low-slung sand islands stretching in a thin line from the Virginia border to Cape Lookout, they were born at the end of the last Ice Age when huge continental glaciers began to melt and the ocean began to rise. Since they formed ten thousand years ago, they have raced the rising waters westward, migrating as much as fifty miles to their present location. The Outer Banks were formed by the force of moving water and moving water shapes them still. The islands were created when rivers and streams carrying silt- and sand-laden glacier meltwater flowed out into the ocean, creating deltas on either side of their main channels. These deposits grew as more silt and sand built up the upstream side. The ocean added sand as it washed over the top of the sandbar during high tides and storms. Steady winds blew sand that accumulated even more. A small, shallow lagoon began to form on the west side and a pair of young islands slowly rose out of the sea. As they grew, prevailing ocean currents slowly ground away the face of the young islands, transporting sand particles down the line; increasing the material at one end as it robbed the same amount from the other. Gradually, the islands began to elongate, stretching into ribbons riding far out into the water. The island chain was broken in points by inlets, which allowed the water still flowing from mainland rivers to empty into the sea, but the island building process continued, with sand building up on the top of the islands while the ocean pulled away on the front of them. This combination of replenishment and erosion has allowed the barrier islands to move as fast as they do for as far as they do. The vital supply of sand provided by the ocean overwash ensures the western side of the islands will be growing even as the eastern side is being washed away. The process is called island migration, and it's key to the survival of the barrier island chain. Next > > More Coastal Articles by Yocum More articles, ghost stories, and tales in CoastalGuide's HELMSMAN
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