Many stretches of the East Anglia, England coastline are prone to heavy of erosion, such as this collapsed section of cliffs at Hunstanton, Norfolk. East Anglia is often used as a shorthand for the Kingdom of the East Angles. Hunstanton, often pronounced by locals as (ˈhʌnstən also known colloquially to locals as 'Sunny Hunny' is a seaside town (population 4961 in Norfolk England Norfolk (ˈnɔrfək is a low-lying county in East Anglia, England, United Kingdom.

Coastal erosion is the wearing away of land or the removal of beach or dune sediments by wave action, tidal currents, wave currents, or drainage (see also beach evolution). In physical Geography, a dune is a Hill of Sand built by Aeolian processes. Sediment is any particulate matter that can be transported by fluid flow and which eventually is deposited as a layer of solid particles on the bed or bottom of a body of A wave is a disturbance that propagates through Space and Time, usually with transference of Energy. Characteristics A tide is a repeated cycle of sea level changes in the following stages Over several hours the water rises or advances up a beach in the flood The Shoreline is where the land meets the sea and it is continually changing Waves, generated by storms, wind, or fast moving motor craft, cause coastal erosion, which may take the form of long-term losses of sediment and rocks, or merely the temporary redistribution of coastal sediments; erosion in one location may result in accretion nearby. Erosion is the carrying away or displacement of solids ( Sediment, Soil, rock and other particles usually by the agents of currents such as wind In Geology, rock is a naturally occurring aggregate of Minerals and/or Mineraloids The Earth's outer solid layer the ‘ Lithosphere The study of erosion and sediment redistribution is called 'coastal morphodynamics'. It may be caused by hydraulic action, abrasion, and corrosion.

On rocky coasts, coastal erosion results in dramatic rock formations in areas where the coastline contains rock layers or fracture zones with different resistances to erosion. Softer areas become eroded much faster than harder ones, which typically result in landforms such as tunnels, bridges, columns, and pillars.

Pacifica, California coast after major storms in 1997 destroyed the houses shown above. Pacifica is a city in San Mateo County California, on the coast of the Pacific Ocean between San Francisco and Half Moon Bay.

On sedimentary coasts, coastal erosion typically poses more of a danger to human settlements than it does to nature itself. Dunwich, the capital of the English medieval wool trade, disappeared over the space of a few centuries due to redistribution of sediment by waves. Dunwich (ˈdʌnɨtʃ is a small town in Suffolk, England, within the Suffolk Coast and Heaths AONB. England is a Country which is part of the United Kingdom. Its inhabitants account for more than 83% of the total UK population whilst its mainland Wool is the fiber derived from the specialized skin cells called follicles of animals in the Caprinae family principally sheep, but the hair of certain species Human interference can also increase coastal erosion: Hallsands in Devon, England, was a coastal village that was washed away overnight, an event possibly exacerbated by dredging of shingle in the bay in front of it. Hallsands is a Deserted village and Beach in south Devon, England, in a precarious position between cliffs and the sea between Beesands Devon is a large county in the South West of England. The county is also referred to as Devonshire, but that is an entirely unofficial name England is a Country which is part of the United Kingdom. Its inhabitants account for more than 83% of the total UK population whilst its mainland Dredging is an Excavation activity or operation usually carried out at least partly underwater in shallow seas or Fresh water areas with the purpose of

The California coast, which has soft cliffs of sedimentary rock and is heavily populated, regularly has incidents of housing damage as cliffs erode. Damage in Pacifica is shown at left. Pacifica is a city in San Mateo County California, on the coast of the Pacific Ocean between San Francisco and Half Moon Bay. Devil's Slide, Santa Barbara and Malibu are regularly affected. Devil's Slide is a coastal promontory in California, USA It lies on the San Mateo County's coastline between Pacifica and Half Moon Bay (Latitude Santa Barbara is a city in Santa Barbara County California, United States. Malibu is an incorporated city in western Los Angeles County, California, United States.

The Holderness coastline on the east coast of England, just north of the Humber Estuary, is the fastest eroding coastline in Europe due to its soft clay cliffs and powerful waves. Holderness is an area of England on the coast of Yorkshire. An area of rich agricultural land Holderness was marshland until it was drained in the Middle Ages The Humber is a large tidal Estuary on the east coast of northern England Groynes and other artificial measure to keep it under control has only sped up the process further down the coast, because longshore drift starves the beaches of sand, leaving them more exposed. A groyne ( groin in the United States is a rigid Hydraulic structure built out from the shore (in Coastal engineering) or from the bank (in rivers and

Wave action - basic

Beach erosion at Cabrillo National Monument, California. For the lighthouse in Mendocino County California see Point Cabrillo Light.

The four main types of wave action can be remembered in this simple way; (by the use of the word "HACC")

• Hydraulic action - occurs when waves striking the cliff face compresses air in cracks on the cliff face. This puts tremendous pressure on the surrounding rock. The air then expands explosively, forcing out pieces of rock. Over time, the cliff face crack grows, sometimes forming a cave. The rock from the cliff face which was removed falls to the bottom of the sea bed and is used for another two wave action. (Attrition and Corrasion (Abrasion)).

• Attrition - occurs when the sea grinds rocks together, causing them to become smoother and reduced in size. As the sea rocks (scree) from side to side it moves the scree causing pieces of scree to collide with other pieces of scree thus causing them to become reduced in size, smoothed and rounded. As well as colliding with other scree, the scree also collides with the cliff face base causing pieces of rock to break off the base of the cliff face contributing to this wave action and to (Corrasion (Abrasion)).

• Corrasion (Abrasion) - occurs when the waves break on the cliff face pounding the cliff face and slowly eroding it. As the sea pounds the cliff faces it also uses the scree from other wave actions to batter and break off pieces of rock from higher up the cliff face which can be used for this same wave action and to (Attrition).

• Corrosion or solution - occurs when the sea uses its low pH (anything below pH 7. 0) to corrode the rocks on the cliff face. Usually the cliff faces to be greatly eroded in this manner are limestone cliff faces, which have a high pH. The rocking action of the sea also provides energy like the stirring motion in a chemistry experiment which speeds up corrosion.

Wave action - extra detail

The ability of waves to cause erosion of the cliff face depends on number of factors, including:

• The hardness or ‘erodibility’ of the rocks exposed at the base of the cliff
  • The key factors in determining erodibility include the rock strength and the presence of fissures, fractures, and beds of non-cohesive materials such as silt and fine sand. A wave is a disturbance that propagates through Space and Time, usually with transference of Energy. Erosion is the carrying away or displacement of solids ( Sediment, Soil, rock and other particles usually by the agents of currents such as wind In Geography and Geology, a cliff is a significant vertical or near vertical rock exposure Hardness refers to various properties of Matter in the Solid phase that give it high resistance to various kinds of shape change when Force In Geology, rock is a naturally occurring aggregate of Minerals and/or Mineraloids The Earth's outer solid layer the ‘ Lithosphere In Anatomy, fissure ( Latin fissura, Plural fissurae) is a groove natural division deep furrow cleft or tear in various parts of A fracture is the (local separation of an object or material into two or more pieces under the action of stress. Silt is Soil or rock derived Granular material of a Grain size between sand and clay Sand is a naturally occurring Granular material composed of finely divided rock and Mineral particles
• The rate at which cliff fall debris is removed from the foreshore
  • Debris removal from the foreshore is dependent on the power of the waves crossing the beach. Debris (ˈdeɪbriː/ /dɛˈbriː is a word used to describe the remains of something that has been otherwise destroyed This energy must reach a critical level or to remove material from the debris lobe. In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός On many cliffs debris lobes can be very persistent and may take many years to completely disappear.
• The presence/absence of a beach at the cliff base.
  • Beaches dissipate wave energy on the foreshore and can provide a measure of protection to the cliff from marine erosion.
• The stability of the foreshore, or its resistance to lowering
  • Lowering of the beach or shore platform through wave action is a key factor controlling the rate of cliff recession. A shore or shoreline is the fringe of land at the edge of a large body of water such as an Ocean, Sea, or Lake. A recession is a contraction phase of the Business cycle. The U If the beach is not lowered the foreshore should widen and become more effective at dissipating the wave energy, so that fewer and less powerful waves reach the cliff.
• The adjacent bathymetry
  • The nearshore bathymetry controls the wave energy arriving at the coast, and can have an important influence on the rate of cliff erosion. Bathymetry is the underwater equivalent to Hypsometry. The name comes from Greek βαθυς deep, and μετρον measure.
• The supply of beach material in the coastal cell from updrift
  • The provision of updrift material coming onto the foreshore beneath the cliff helps ensure a stable beach.

Factors affecting the erosion rate

First order (most important)

• Geological structure and lithology: hardness, height, fractures/faults
• Wave climate: prevailing wave direction, wave breaking point
• Sub-aerial climate: weathering (frost, etc. ), stress relief swelling/shrinkage
• Water-level change: groundwater fluctuations, tidal range
• Geomorphology

Second order

• Weathering and transport slope processes
• Slope hydrology
• Vegetation
• Cliff foot erosion
• Cliff foot sediment accumulation
• Resistance of cliff foot sediment to attrition and transport

Third order

• Coastal land use
• Resource extraction
• Coastal management

See also

• Coastal and oceanic landforms
• Natural arch
• Blowhole
• Bioerosion
• Modern recession of beaches
• Coastal defense
• Beach nourishment
• Submersion
• Coastal and Estuarine Research Federation (CERF)

External links

• Coastal Erosion Information from the Coastal Ocean Institute, Woods Hole Oceanographic Institution
• Wave Erosion
• Time-lapse movie of beach erosion in Australia
• Examine an example of wave erosion
• Erosion & Flooding in the Parish of Easington
• Some interesting teaching resources
• Examples of coastal landforms
• Social & Economic Costs of Coastal Erosion & Inundation from "NOAA Socioeconomics" website initiative

Images:

• Work to reduce coastal erosion at Lyme Regis in Dorset 2006
• Images of Coastal features