Coasts: Key Terms
Coasts: Key Terms
Coasts: Key Terms
Coastal Processes
Abrasion – Also called corrasion; occurs when waves pick up sediment and hurl it against the cliff, wearing it away like sandpaper.
Attrition – Rocks and pebbles carried by waves smash into each other, breaking into smaller, smoother pieces.
Deposition – When waves lose energy and drop the sand, shingle, or sediment they’ve been carrying.
Erosion – The wearing away of the land by the sea, mainly by destructive waves.
Hydraulic action – The power of waves forcing air and water into cracks in rocks, causing them to break apart.
Longshore drift (LSD) – The zigzag movement of beach material along the coast caused by waves hitting the shore at an angle.
Solution (corrosion) – The chemical action of seawater dissolving soluble rocks like limestone and chalk.
Transportation – The movement of sediment along the coast by waves.
Coastline Formation
Concordant coastline – A coastline with rock layers that run parallel to the sea, causing even erosion and forming coves.
Discordant coastline – A coastline with alternating bands of hard and soft rock at right angles to the sea, creating headlands and bays.
Hard rock – Resistant rock types like limestone and chalk that erode slowly and form steep cliffs.
Soft rock – Less resistant rock types like clay and sand that erode easily and form bays.
Landforms of Coastal Erosion
Arch – A natural opening through a headland formed when a cave erodes all the way through.
Bay – A wide inlet of the sea formed where soft rock has been eroded between harder rock headlands.
Cliff – A steep rock face formed by the erosion of land by waves.
Cave – A hollowed-out area in a cliff formed when waves exploit cracks in rock.
Headland – A section of land jutting out into the sea, made of harder rock that erodes more slowly.
Stack – A tall, isolated column of rock left when the roof of an arch collapses.
Stump – A small rock remnant of a former stack, worn down by erosion.
Wave-cut platform – A flat area at the base of a retreating cliff, created by the collapse of eroded cliff rock.
Landforms of Coastal Deposition
Bar – A ridge of sand or shingle formed when a spit grows across a bay, joining two headlands.
Beach – A build-up of sand and shingle formed by constructive waves in sheltered areas like bays.
Berm – A ridge at the top of a beach formed by storm waves.
Lagoon – A body of water cut off from the sea by a bar or tombolo.
Sand dunes – Mounds of sand formed when windblown sand is trapped by vegetation or debris.
Spit – A stretch of sand or shingle projecting out to sea, formed by longshore drift.
Tombolo – A spit that connects an island to the mainland.
Coastal Hazards & Opportunities
Coastal squeeze – Loss of habitat due to the fixed seawall on one side and rising sea levels on the other.
Eutrophication – Excess nutrients (often from fertilisers) cause algal blooms that reduce oxygen and kill marine life.
King tide – A very high tide that can cause extreme flooding when combined with storms.
Storm surge – A sudden rise in sea level caused by low-pressure weather systems and high winds.
Tsunami – A large sea wave caused by an underwater earthquake.
Coastal Management
Beach nourishment – Adding sand to a beach to replace what’s lost to erosion.
Gabions – Wire cages filled with rocks placed at the base of cliffs to absorb wave energy.
Groynes – Wooden or stone barriers built at right angles to the shore to trap sand and prevent longshore drift.
Hard engineering – Man-made, high-cost defences like sea walls and rock armour to protect coastlines.
Integrated Coastal Zone Management (ICZM) – A strategy that uses both hard and soft engineering to meet the needs of all stakeholders.
Managed retreat – Allowing certain areas of coast to flood naturally to reduce pressure elsewhere.
Revetments – Sloping wooden or concrete structures built to absorb wave energy.
Sea wall – A curved concrete wall built at the edge of the sea to deflect wave energy.
Soft engineering – Using natural systems, like dunes or marshes, to reduce the effects of coastal erosion.
Tropical Storms
Coriolis effect – The rotation of the Earth causes moving air and water to turn, helping storms to spin.
Eye of the storm – The calm centre of a tropical storm, surrounded by strong winds and heavy rain.
Storm surge – A rapid rise in sea level caused by the pressure and winds of a tropical storm.
Tropical storm – A rotating, low-pressure weather system with strong winds and heavy rain, known as hurricanes, typhoons, or cyclones depending on location.
Coastal Defence Case Study: Nassau County, Florida
Beach nourishment – In Nassau County, sand was added to beaches to reduce erosion and protect turtle habitats.
Dune restoration – Planting grasses like sea oats to stabilise sand dunes and absorb wave energy.
Rock revetments – Large boulders placed along the coast to break the power of waves and reduce erosion.
Sand fencing – Wooden barriers installed to trap sand and help dunes grow.