2.2c+-+Coasts

**__From the syllabus__**

 * Demonstrate an understanding of wave processes in eroding a coastline and re-sorting and depositing materials removed through erosion.
 * Candidates should understand the types of waves (constructive and destructive) and the components of waves, swash and backwash.
 * The erosional processes of wave action should include an understanding of corrasion, hydraulic action, corrosion and attrition.
 * Transport of material along a coastline should be appreciated; onshore and offshore movements together with an understanding of movement along a coastline (longshore drift).
 * The action of wind in shaping coastal sand dunes should also be understood.
 * Describe and explain the landforms associated with these processes. A study should be made of the following coastal landforms: Cliffs, wave-cut platforms, caves, arches, stacks, bay and headland coastlines, beaches, spits and bars, coastal sand dunes and marsh.
 * Describe the conditions required for the development of coral reefs.
 * Describe fringing and barrier reefs and atolls.
 * Demonstrate an understanding that the natural environment presents hazards and offers opportunities for human activities. Reference should be made to flooding. //(NB: For coasts you need to have an idea of the ways that cliff erosion can present a danger for nearby residents.)//

**__Key term list__**
Erosion - Wearing away of the land Abrasion / corrasion - Pebbles, stones are flung up by breaking waves onto cliffs, particularly powerful as missiles during storms. Attrition - Particles are reduced in size and rounded off by colliding with one another as they are washed in the waves. Erosion grinds down the cliff-fall material. Hydraulic action - Erosion caused by water being forced into cracks in the rock and the shock of this pressure weakens and breaks rocks. Solution/ corrosion- Type of chemical weathering where minerals are broken down often by weak acids. Weathering - wearing away of the land by atmospheric conditions e.g. freeze-thaw or solution Cave - feature found in a headland created by erosion processes Arch - initially starts as a cave and the headland is fully eroded through Stack - where the roof of an arch collapses and leaves behind a protruding piece of land Stump - when a stack is eroded and weathered and eventually collapses. This is covered at high tide. Blow hole - A chimney or pipe leading from a cave up through a cliff to the surface. Caused by erosion and often exploitation of joints in the geology. Wave cut platform - A flat rock area in the intertidal zone created by destructive waves (also often by chemical weathering if a limestone area). Wave cut notch Overhang Swash - Movement of water up the beach away from the sea as a wave reaches the shore Backwash - movement of water back towards the sea after a wave has broken Constructive waves - Low frequency 6-8 per minute waves which have elliptical water motion, with powerful swash and weak backwash. They build deposition. Destructive waves - High frequency 13-15 per minute waves which have circular water motion, with weak swash and powerful backwash. They erode. Fetch - The distance of uninterrupted water surface over which the wind has blown to form waves. Longer fetch means higher energy waves. Longshore drift - (LSD) Movement of sediment in a zig-zag pattern up and down the shore with swash and backwash resulting in an overall direction along the coast. Slumping - Slumping is triggered by undercutting at the base of cliffs with rotation in the slip plane. Spit - Long ridges of sand and shingle attached to land at one end. Bar - Coarse grained deposit of sediment extending across the mouth of bay, sometimes reaching the other side and sealing off the entrance Tombolo -** Shingle ridge linking the mainland to an island
 * Coastline - Where the land meets the sea


 * Add coral reefs bits ......**

**__**__Case Studies__**__**

 * New Forest (coastal management) (textbook p. 306)
 * Cyclone Nargis in Myanmar (tropical storm/coastal flooding in an LEDC) (computer, but there is a similar case study about storm surges in India on textbook p. 312)