Coastal Processes

Waves created by friction of wind on water. Top of wave = Crest Bottom of wave =Trough Wave Length = Crest to Crest

When waves move into shallow water they break as the top of the wave moves faster than the lower half...

Construction vs. Destruction When a wave breaks, water is washed up the beach - this is called the swash. Then the water runs back down the beach - this is called the backwash. With a destructive wave, the backwash is stronger than the swash. With a constructive wave, the swash is stronger than the backwash.

Destructive [take sand away]

Constructive [add sand]

Coastal Erosion LOOK FAMILIAR???!!! RIVERS???!!!! Hydraulic Action: The force of the water breaks away the coast. Abrasion: Debris (such as sand) interactions with coasts. Attrition: Large rocks interaction with coasts. Corrosion: All water is a little acidic; some rocks are dissolved (eg. Limestone) LOOK FAMILIAR???!!! RIVERS???!!!!

Erosion Process Undercutting: Wave action + erosion along shoreline creates cliff and then wears down until collapse creating some new features.

Features Caves – weakest rocks erode first and eventually collapse Bays – erosion of softer rocks and large area is created. Headlands – areas where harder rock resists erosion. Tunnels – when waves eventually erode through headland. Arch – erosion through headland continues to grow.

Stacks – when arch collapses. Wave-Cut Platform – the final remainder of a headland that has been eroded away.

Longshore drift Waves can approach the coast at an angle because of the direction of the wind. Swash, angled, brings sand onto the beach + Backwash, removes it straight back = Long Shore Drift: movement of sand along a beach

Deposition Spit: Sand carried away by long shore drift; long narrow ridge of sand Tombolo – If a spit connects an island to the mainland.

Groynes – Barriers built to stop long-shore drift.

In-land Coastal Processes Estuaries: Mix of fresh and salt water Fjords: Deep U shaped river valleys that go all the way to the ocean.