Coursework Theory section Understand the Theories related to the Fieldwork at Reculver on the North Kent Coast.

Longshore Drift This movement of sediment along the coastline is called longshore drift. This process occurs at the fieldwork site (Reculver) Direction of movement swash Backwash Backwash is always at right angles to the beach

Destructive Waves The backwash of the wave, due to the way in which it breaks on the shore, is greater than the swash. This carries material away from the beach.

Constructive Waves The much lower wave breaks on the shore and the swash carries material up the beach. The backwash is much weaker and cannot carry the material away so the beach is built up.

Attrition Hydraulic Action Abrasion Corrosion Processes of Erosion Acid cid

Abrasion/Corrasion This is the process by which the coast is worn down by material carried by the waves. Waves throw these particles against the rock, sometimes at high velocity. Hydraulic Action This process involves the force of water against the coast. The waves enter cracks (faults) in the coastline and compress the air within the crack. When the wave retreats, the air in the crack expands quickly causing a minor explosion. This process is repeated continuously. Corrosion This is the chemical action of sea water. The acids in the salt water slowly dissolve rocks on the coast. Limestone and chalk are particularly prone to this process. Attrition Material carried by the waves bump into each other and so are smoothed and broken down into smaller particles.

Wave cut platform and cliff retreat  The waves attack the base of the cliff through the processes of abrasion, corrosion, hydraulic action and attrition.  Over time the cliff will be undercut and a wave-cut notch is formed.  Eventually the cliff becomes unstable and collapses. Further cliff retreat will form a wave-cut platform. Important The processes by which this feature forms are not dominant at the field work site at Reculver.

Cliff retreat at Reculver 1. Rain 2. The material of the cliff soaks up the rainfall. 3. Gravity causes the, now heavy, cliff to collapse. 4. High tides and storm waves will transport the cliff debris out to sea. SEA 5. The cliff debris offers some protection, to the cliffs behind, from storm waves.

Spring sapping at Reculver 1. Rain 2. Rainfall percolates through the cliff 3. It emerges at the base of the cliff 4. Small particles of sand swept out from the cliff by the spring water. 5. The cliff is undercut by the spring sapping which encourages cliff collapse and retreat. SEA