Coasts and Oceans
Coasts and Oceans
Understand coastal processes, landforms and management. Waves are formed by wind over the sea; learn swash and backwash, constructive versus destructive waves (long, low, frequent waves build beaches; short, steep, powerful waves erode), and longshore drift. Erosion processes are hydraulic action, abrasion (corrasion), attrition and solution; weathering includes freeze-thaw, salt and biological weathering.
Erosional landforms: headlands and bays, cliffs, wave-cut platforms, caves, arches, stacks and stumps. Depositional landforms: beaches, spits, bars, tombolos and sand dunes. Learn mass movement (rockfall, landslide, slumping) and coastal management: hard engineering (sea walls, groynes, rip-rap, gabions) and soft engineering (beach nourishment, dune stabilisation, managed retreat). Understand coral reefs, mangroves and sea-level change, important in The Bahamas and the Caribbean.
Traps: confusing constructive and destructive waves; saying longshore drift moves material out to sea (it moves it along the shore); muddling a spit (attached at one end) with a bar (across a bay); and forgetting that groynes starve neighbouring beaches of sediment.
Rule of thumb: destructive waves have a strong backwash and remove material; constructive waves have a strong swash and add material.
Worked example: A spit forms where longshore drift carries sediment along a coast until the coastline changes direction; deposition continues into open water, building a ridge attached to land at one end, often with a hooked end where wave direction changes.