COASTAL PROCESSES

HOME | AS/A LEVEL | GCSE | YEAR 9 | YEAR 8 | YEAR 7
 

 

PROCESSES AND TYPES OF EROSION

Wave pounding. The mass of water of a wave is huge and a wave breaking can exert a force of up to 30 tonnes/ square meter.

Hydraulic pressure. Air is trapped in a crevice in either the cliff or sea wall. Explosive force breaks off particles of debris.

Abrasion/corrasion. Most dominant and effective, especially storm waves. is erosion by sand, shingle, boulders (load) as they are hurled against the cliff/sea wall by waves

Attrition. Sediment particles smash together and are rounded as sharp adges are broken off. Load is made smaller.

Corrosion/solution. Chemical reaction of sea water - only some rock types especially chalk and limestone. Carbonation of limestone. Growth of salt crystals which disintegrate the rock. Can occur above high tide mark from sea salt spray.

Sub-aerial erosion. Non-marine. Direct rain action on cliffs, weathering and mass movement.

Human Activity. Increased pressure on cliff tops by building weight. Removal of protective building material for building trade, or through placing groynes further up the coast starving beaches further down.

 

What affects rates of erosion?

  1. breaking point of the wave

  2. wave steepness

  3. depth of the sea

  4. the fetch

  5. the coastline shape (aspect)

  6. supply of beach material

  7. beach width

  8. rock type and therefore resistance

  9. rock structure (eg heavily jointed)

  10. Sub-aerial erosion processes which work togther with wave erosion

 

 

Dunraven Bay, South Glamorgan is a SAC (Special Area of Conservation)

Geology. Thin bedding planes of limestone and shales make these cliffs susceptible to both wave and sub-areial erosion.

notice the superb wave cut platform and the stream flowing over the top of the cliff

photo:G.Stott

Map of Britain showing resistance of the geology to denudation (Clayton & Shamoon, 1998).

WEB LINKS

NERC publication: Diasappearing Coasts

 

Marine Climate Change Impacts Partnership. Coastal Erosion and Coastal Geomprphology: This is an excellent report. Even if you don't read anything else, go through it as the diagrams, photos and tables of information are excellent.