Coast definitions Flashcards
Abrasion
A form of erosion where loose material and sediment ‘sandpapers’ the walls and floor of a river, cliff or glacier. Also known as attrition
Backshore
The upper beach closest to the land, including any cliffs or sand dunes
Bar
A section of sand caused by deposition. They join two sides of a bay together, creating a lagoon behind the bar
Beach morphology
The surface shape of the beach
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 or recession
Coastal recession
The retreat of a coastline due to erosion, sea-level rise or submergence
Concordant coast
A coastline where bands of alternate geology run parallel to the coast
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 the cliff
Corrosion
The weak acid in seawater and some types of seaweed react with particular rock minerals, causing erosion and weakening
Dalmation 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
DEFRA’s 1:1 Cost-Benefit Analysis
The evaluation of a coastal town’s economic value compared to the cost of the management required
Discordant coast
A coastline where bands of alternate geology run perpendicular to the shore
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
Emergent coast
A coastline that is advancing relative to the sea level at the time
Estuary
The point at where a river meets an ocean, often muddy or silty. Sometimes estuaries become exposed at low tide
Eustatic
Global changes to sea levels
Fetch
The length of water over which the wind has travelled
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
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)
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
Geology
The physical structure and arrangement of a rock
Glacial erosion
The removal of loose material by glacier ice, involving plucking, abrasion, crushing and basal meltwater (necessary in the formation of fjords)
Grading
The layering of sediments based on their size
Groyne
A form of hard engineering. Low lying concrete or wooden walls, constructed perpendicular to the sea front, and run out to sea. They encourage the trapping of sediment to reduce erosion caused by longshore drift or winds
Hard management
The use of concrete structures to reduce or halt the recession of a coastline. Includes groynes, rock armour, sea walls
High energy environment
A coast where wave action is predominately large destructive waves, causing much erosion
Hydraulic action
The pressure of compressed air forced into cracks in a rock face will cause the rock to weaken and break apart
ICZM
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
Impermeable
A rock that does not allow water to pass through it
Isotatic
A local change in sea level due to a change in local coastline or land height
Littoral cell
An area of coastline which has all sediment processes occuring- erosion, transportation and deposition.
Not a closed system.
Longshore drift
The transportation of sediment along a beach. Longshore drift is determined by the direction of the prevailing wind
Low-energy environment
A coast where wave action is predominately small constructive waves. Depositon usually takes place leading to beach accretion
Mass movement
When there is a large downhill movement of material, usually from a cliff-face, as the rock is often weak there due to erosion. The movement is caused by gravity
Near shore
The area before the shore where the wave steepens and breaks before they reach the shore, and then reform before breaking on the shore. It extends from the low tide zone and then out to sea
Permeable
A rock that allows water to pass through it
Plant succession
Changes to a plant community over time due to adaptation to changing growing conditions (e.g sand dunes and salt marshes)
Ria
Narrow winding inlet which is deepest at the mouth, formed when sea level rise causes coastal valleys to flood
Rock armour
Large rocks or concrete blocks, used as barricades to reduce marine erosion at the base of cliffs
Saltation
A form of transportation where smaller sediment bounces along the seabed pushed by currents. This sediment is too heavy to be picked up by the flow of the water
Salt marsh
In sheltered bays or behind spits, salts and minerals will build up. Vegetation may establish, further stabilising the marsh
Sand dune
A depositional landform, where sand and sediment build up around driftwood and accumulate over time
Sea wall
A hard-management coastal defence, where a concrete wall is built parallel to the seafront, to redirect the energy of waves away from sensitive cliffs or the edge of a coastal town
Sediment cell
Sections of the coast boardered by prominent headlands. Within these sections, the movement of sediment is almost contained, and the flows of sediment should act in dynamic equilibrium
Sediment budget
Uses data of inputs, outputs, stores and transfers to assess the gains and losses of sediment within a sediment cell
SMP
Shoreline Management Plan
- identifies all the activities, both natural and human, which occur within the coastline area of each sediment cell
- They use this to recommend a combination of four actions for each stretch of that coastline
- Hold the Line, Advance the Line, Managed Realignment and No Active Intervention
Soft management
The use of natural materials and environmentally sustainable approaches to reduce coastal recessions.
Includes: beach nourishment, managed retreat and sand dune encouragement
Spit
A long depositional landform, formed from sand and shingle
Subaerial processes
The combination of mass movement and weathering that affects the coastal land above sea
Till
Deposit of angular rock fragments in a finer medium
Tombola
A spit joining a mainland to an island
Wave quarrying
When air is trapped and compressed against a cliff which causes rock fragments to break off the cliff over time
