Coastal processes are a key focus in IB Geography, particularly within Option B: Oceans and Coastal Margins. Coastal landforms are created and shaped by the interaction of waves, tides, currents, and sediment movement along coastlines. Understanding these processes helps explain why coastlines vary in shape and why they continue to change over time.
One of the most important coastal processes is erosion. Erosion occurs when waves wear away rock and sediment along the coastline. Hydraulic action happens when waves force water and air into cracks in rocks, weakening them over time. Abrasion occurs when waves throw pebbles and sand against cliffs, gradually wearing them down. Solution affects coastlines made of soluble rock, such as limestone, where chemical reactions dissolve rock material.
Erosion leads to the formation of distinctive coastal landforms. On headlands, erosion can create caves, arches, stacks, and stumps as weaknesses in rock are exploited by wave action. Softer rock is eroded more quickly than harder rock, resulting in an uneven coastline with bays and headlands. In IB Geography, these features are often used to illustrate differential erosion.
Transportation is another key coastal process. Waves and currents move sediment along the coast through processes such as longshore drift. Longshore drift occurs when waves approach the shore at an angle, transporting material along the coastline in a zigzag pattern. This process redistributes sediment and plays a major role in shaping beaches and coastal landforms.
Deposition happens when waves lose energy and drop the sediment they are carrying. This commonly occurs in sheltered areas such as bays or where wave energy decreases. Deposition creates landforms such as beaches, spits, bars, and tombolos. Spits form when longshore drift deposits sediment beyond a bend in the coastline, while bars can cut off bays to form lagoons.
Wave type strongly influences coastal processes. Destructive waves, which are steep and powerful, cause erosion by removing material from the coast. Constructive waves are gentler and deposit sediment, building up beaches. The balance between these wave types determines whether a coastline is eroding or accreting.
In IB Geography, it is important to recognise that coastal processes operate as a system. Changes in one part of the coastline can affect sediment supply and erosion elsewhere. Human activities such as coastal management can also alter natural processes, sometimes increasing erosion in other locations.
Overall, coastal landforms are shaped by the combined effects of erosion, transportation, and deposition driven by wave energy and sediment movement. These dynamic processes ensure that coastlines are constantly changing environments.
RevisionDojo helps IB Geography students understand coastal processes clearly by linking physical processes to landforms and supporting confident, exam-ready explanations.
