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Coastline featuresCoastline features Coastlines are where ocean or sea meets land. Some coastlines are shaped by the action of waves crashing against them, wearing away the rocks. Along others, sand and shingle are piled up in beaches or mudflats. The coast is a continuing battle between sea and land. Sometimes the sea “loses” as shingle, sand or mud piles up and the land grows. In other places, the sea “wins” as waves, currents and tides batter and break up the coast. Even hard rocks like granite are gradually worn away, especially during storms when high winds whip up huge waves powerful enough to smash pebbles and boulders against the shore.

A sea arch on a headlandA sea arch on a headland

Coastal erosion

The shape and features of a coastline depend on its rocks, winds and currents. Very hard rocks erode slowly and stand out as high headlands. Waves build up higher in the direction of the prevailing (or main) winds in the region. This means waves have their biggest effect on coasts exposed to these winds. Sometimes waves may carve a hole, or arch, right through a headland. If the roof of the arch later collapses, part of it is left standing alone in the sea. This is called a stack.

Horseshoe Bay, Queensland, AustraliaHorseshoe Bay, Queensland, Australia


The longest spit in the world is the 110-km (68-mile) Arabat Spit in the Sea of Azov, Ukraine.

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