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Disappearing beaches
Grim examples
Role of beaches
Solving beach erosion?
Global warming and sea levels

Update: Flooded Island


 

Here's one way that sea cliffs get formed. Sometimes the sand hangs around to form a beach; eroding cliffs are a major source of beach sand.

Image by Why Files Staff.

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A thin line of protection
All geology is about change. Continents, as we know, drift gradually around the globe. The ocean floor is being created at the mid-ocean ridges and recycled beneath the crust at the margins. Mountains rise up and gradually erode back.

erosion diagram
These changes are slow, inexorable, and usually gradual. The changes on a beach, in contrast, can happen literally overnight, at least during a storm. Even without storms, sand may be lost to longshore drift (the currents that parallel coastlines). Or sand may be pulled to deeper water, essentially lost to the coastal system.

On the positive side, sand arrives from eroding uplands, river sediment, and longshore drift.

How's the beach this year? That depends on recent storms. To paraphrase Heraclitus, the ancient philosopher, "You can never step on the same beach twice."

Change -- with a purpose
All this change, however, is useful to those who live sheltered by the beach. Aside from providing recreation and wildlife habitat, beaches are protection for whatever lies behind. Like those foam-packed highway barriers that give way on impact, beaches absorb energy from the sea. "Beaches are a very significant dissipater of wave energy," says O'Connell. "The wider, more gently sloping and permeable they are, the more energy will dissipate before it reaches landward development or natural resources."

Got any energetic ideas for saving the beaches?


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