Coastal Erosion
Erosion dramatically causes constant change to coastlines around the world. In the United Kingdom the East coast is most vulnerable due to the geology (rock type) of the cliffs that border it. On the East Coast the rocks are sedimentary and are soft making them much more easily eroded, than those on the West Coast. The rate of erosion is due to the relationship between the power and impact of waves and the cliffs rock structure and type.
Examples of rock include clay and red crag, by which you will discover on your coastal fieldtrip to Walton-On-The-Naze.
Below are some scanned resources taken from my geography filedwork study. These were created for my coursework on the subject of erosion and transportational processes at Walton.
Diagram showing a rough divide between Hard and Soft Rock in Britain.
Hard & Soft Rock division
Rock Rubbings
During my visit to Walton On-The-Naze for a coastal fieldwork study we examined the two main rock types: Red Crag and London Clay.
Walton-On-The Naze is a small town situated on the East Coast, North of Clacton. London Clay was formed from compacted silt from Rivers flowing into the sea years ago. Both London Clay dating back 54 million years and Red Craig, 2 million years ago are soft sedimentary Rocks. This means rates of erosion are increased. Erosion is caused by the flowing processes listed on the right.
Evidence that cliffs are being eroded is made very clear. Pill boxes which served in the Second World War based on the land can now be seen distibuted on the beach and in the sea. Satistics show that these cliffs are retreating by as much as two metters a year.
For more information about erosion at walton visit:
Quiz
Are you ready to take a coasts quiz?
Erosion Processes
Hydraulic Action - When waves hit the base of a cliff the force causes trapping and compression of air and water within the cracks in the rock. As the wave retreats due to gravity (Backwash) the pressure is released causing air and water to expand. The rock breaks and crumples as large fragments fall to the beach.
Corrasion (Abrasion) - Rocks are eroded as waves hurl rocks and pebbles against the cliff causing collisions, wearing the rocks in contact away.
Attrition - The movement of waves cause rocks and boulders to colide and hit against each-other. They are gradually worn down into smaller fragments, losing their angularity.
Corrosion - Chemicals, acids and salt dissolved in the seawater slowly dissolve a cliff and rot the rocks. Rock such as limestone and chalk are most prone to this type of erosion.
Coastal Cycle
Weathering Effects
Another way by which cliffs are retreating landwards is Weathering.
Weathering Processes:
Slumping
Mudflows
Rock fall