Key terms - coasts

• What is abrasion?


  A form of erosion where loose material and sediment 'sandpapers' the walls and floors of the river, cliff or glacier. Also known as attrition.
• What is the backshore?

  The upper beach closest to the land, including any cliffs or sand dunes.
• What is a bar?


  A section of sandy beach closest to the land, including any cliffs or sand dunes.
• What is beach morphology?


  The surface shape of the beach.
• What is beach nourishment?


  The addition of sand and sediment to an eroding beach by humans. The new material will be eroded by the sea which saves the cliffs or sand dunes from erosion and recession.
• What is coastal recession?

  The retreat of a coastline due to erosion, sea-level rise or submergence.
• What is a concordant coast?


  A coastline where bands of alternate geology run parallel to the coast.
• What is corrasion?


  A form of mechanical erosion where material and sediment in the sea is flung at the cliff-face as waves break against it, this breaks up the rocks making up the cliff.
• What is corrosion?


  The weak acid in seawater and some types of seaweed react with particular rock minerals, causing erosion and weakening.
• What is the Dalmatian coast?


  A concordant coastline with several river valleys running perpendicular to the coast. These valleys become flooded due to sea levels rising and produce long islands and inlets.
• What is a cost-benefit analysis?

  The evaluation of a coastal town's economic value compared to the cost of the management required.
• What is a discordant coast?


  A coastline where bands of alternate geology run perpendicular to the shore.
• What is dynamic equilibrium?


  A system where its inputs and outputs are in balance. Short term changes can affect this balance, negative feedback loops help to take the system back to dynamic equilibrium.
• What is an emergent coast?


  A coastline that is advancing relative to the sea level at the time.
• What is an estuary?


  The point at where the river meets an ocean, often muddy or silty. Sometimes estuaries become exposed at low tide or hazardous to transverse in a boat due to sandbanks.
• What is eustatic?


  Global changes to sea levels.
• What is the fetch?


  The length of water over which the wind has travelled.
• What is a fjord?


  Long narrow inlet of sea water which is between steep mountains. They are created when sea levels rise relative to the land, flooding coastal glacial valleys.
• What is the foreshore?


  The lower part of the beach covered twice a day at high tide (the part of the beach that receives the most regular wave action).
• What is freeze-thaw?


  A form of physical sub-aerial weathering where water freezes in the cracks of a rock, expands and enlarges the crack. This weakens the rock overtime leaving it more open to erosion.
• What is geology?


  The physical structure and arrangement of a rock.
• What is glacial erosion?


  The removal of loose material by glacier ice, involving plucking, abrasion, crushing and basal meltwater (necessary in the formation of fjords).
• What is grading?


  The layering of sediments based on their size.
• What is a groyne?


  A form of hard-engineering. Low-lying concrete or wooden walls, constructed perpendicular to the seafront and run out to sea. They encourage the trapping of sediment to reduce erosion caused by longshore drift or by winds.
• What is hard management?


  The use of concrete structures to reduce or halt the recession of a coastline. Includes: groynes, sea walls, rock armour.
• What is a high-energy environment?


  A coast where wave action is predominantly large destructive waves, causing much erosion.
• What is hydraulic action?


  The presence of compressed air forced into cracks in a rock face will cause the rock to weaken and break apart.
• What is Integrated Coastal Zone Management?


  Large sections of coastline (often sediment cells) are managed with one integrated strategy and management occurs between different political boundaries. It usually follows a holistic approach and takes into consideration different players.
• What is impermeable?


  A rock that does not allow water to pass through it.
• What is isostatic?


  A local change in sea level due to a change in local coastline or land height.
• What is a littoral cell?


  An area of coastline which has all sediment processes occurring sources, transport and sinks. A littoral cell is not a closed system.
• What is longshore drift?


  The transportation of sediment along a beach. Longshore Drift is determined by the direction of the prevailing wind.
• What is a low-energy environment?


  A coast where wave action is predominantly small constructive waves. Deposition usually takes place leading to beach accretion.
• What is mass movement?


  Where there is a large downhill movement of material usually from a cliff-face. Here, the rock is often weak due to erosion and the movement is caused by gravity.
• What is the nearshore?


  The area before the shore where the wave steepness and breaks before they reach the shore and then reform before breaking on the beach. It extends from the low-tide zone and then out to sea.
• What is permeable?


  A rock that allows water to pass through it.
• What is plant succession?

  Change to a plant community over time due to adaptation to changing growing conditions (eg. sand dunes and salt marshes).
• What is a ria?


  Narrow winding inlet which is deepest at the mouth, formed when sea levels rise causing coastal valleys to flood.
• What is rock armour?


  Large rocks or concrete blocks, used as barricades to reduce marine erosion at the base of cliffs.
• What is saltation?


  A form of transportation where smaller sediment bounces along the sea bed pushed by currents. This sediment is too heavy to be picked up by the flow of the water.