Costal

• Waves


  Ripples in the sea caused by the transfer of energy from the wind blowing over the surface of the sea. The largest waves are formed when winds are very strong, blow for lengthy periods and cross large expanses (areas) of water.
• Erosion


  The wearing down and removal of material by a moving force.
• Deposition


  Occurs when material being transported by the sea is dropped due to the sea losing energy.
• Fetch


  The distance across the open sea over which the wind blows towards the coasts at a particular place.
• Constructive Waves


  Gently breaking waves with a strong swash and weak backwash, leading to deposition of material on the beach.
• Destructive Waves


  Powerful waves with a weak swash and strong backwash, leading to erosion of material on the beach.
• Crest


  The top of a wave.
• Trough


  The base of a wave.
• Wave height


  The vertical distance from trough to crest.
• Wave length


  The horizontal distance between two successive crests.
• Wave frequency


  The number of waves breaking per minute.
• Weathering


  When rock is broken down in one place.
• Chemical weathering


  The decomposition of rock caused by a chemical change within the rock; sea water can cause chemical weathering of cliffs.
• Mechanical weathering


  Weathering processes that cause physical disintegration or break up of exposed rock without any change in the chemical composition of the rock, e.g. freeze thaw.
• Freeze-thaw weathering


  It occurs when water enters the cracks during the warmer day and freezes during the colder night. As the water turns into ice it expands and exerts pressure on the surrounding rock causing pieces to break off.
• Mass movement


  The downhill movement of weathered material under the force of gravity. The speed can vary.
• Sliding


  Occurs after periods of heavy rain when loose surface material becomes saturated and the extra weight causes the material to become unstable and move rapidly downhill.
• Slumping


  Rapid mass movement which involves a whole segment of the cliff moving down-slope along a saturated shear-plane or line of weakness.
• Hydraulic Action


  Erosion caused by the force of the waves against the cliff breaking the rock.
• Attrition


  Erosion caused when rocks transported by waves bump into each other and break into smaller pieces.
• Abrasion


  Erosion when rocks carried by the waves scrap and scratch the cliff face breaking rock.
• Solution


  Soluble particles are dissolved into the waves.
• Longshore Drift


  The zigzag movement of sediment along a shore caused by waves going up the beach at an oblique angle (non-right angle) (this is wash) and returning at right angles (backwash). This results in the gradual movement of beach materials along the coast.
• Spit


  A depositional landform formed when sediment extends from the shore out to sea. It usually has a curved end because of opposing winds and currents.
• Discordant coasts


  Coastlines where the geology alternates between strata (or bands) of hard rock and soft rock.
• Wave cut platforms


  A rocky,level shelf at or around sea level representing the base of old, retreated cliffs.
• Cave


  A large hole in the cliff caused by waves forcing their way into cracks in the cliff face.
• Arch


  A wave-eroded passage through a small headland. This begins as a cave which is widened and deepened gradually until it is cut through to be an arch.
• Stack


  An isolated pillar of rock left when the top of an arch collapsed. Over time further erosion reduces the stack to a smaller, lower stump.
• Stump


  The base of a collapsed stack.
• Beach


  The zone of deposited material that extends from the low waterline to the limit of storm waves.
• Sand dunes


  Coastal sand hill above the high tide mark shaped by wind action and covered by grasses and shrubs.
• Hard engineering


  The use of concrete and large artificial structures by humans to defend the coast against natural erosion processes.
• Groynes


  A wooden barrier built out into the sea to stop the longshore drift of sand and shingle and so cause the beach to grow. It is used to build beaches to protect against cliff erosion however by trapping sediment it deprives another area, down-drift, of new beach material (sand).
• Rock armour


  Large rocks dumped on the beach as part of the coastal defences.
• Gabions


  Steel wire mesh filled with rocks used in coastal defences.
• Beach nourishment


  The addition of new materials to a beach artificially, through the dumping of large amounts of sand or shingle.
• Soft engineering


  Managing erosion by working with natural processes to help resource beaches and coastal ecosystems.
• Dune regeneration


  Action taken to build up dunes and increase vegetation to strengthen the dunes and prevent excessive coastal retreat. This includes the re-planting of grass to stabilise the dunes.
• Coastal realignment


  Creating an engineered new position of a coastline.