Coasts Flashcards
Name the sections of the littoral zone from cliffs/dunes to out at sea.
Backshore, foreshore, nearshore, offshore.
Broadly outline the lithology of the UK coastline.
South East - mostly sedimentary
North - igneous and metamorphic
Cornwall - sedimentary and igneous
Wales - sedimentary (slate)
Norther Ireland got it all
Give 2 example of low-energy coastlines.
Mediterranean Sea locations
East-Anglian coasts
Give 2 examples of high-energy coastlines.
Atlantic coast of Norway
Atlantic coast in Scotland
Give a UK example of a concordant coast.
South-facing Dorset coast line.
Give a UK example of a discordant coast.
East-facing Dorset coast line.
What rock types are present in the Dorset concordant/discordant example?
Clay/sand, chalk, limestone.
What are rock strata?
Layers of rock
What are bedding planes?
Horizontal cracks in strata (caused by gas)
What are joints?
Vertical cracks in strata (caused by movement)
What are folds?
Rocks buckling/crumbling due to pressure
What are faults?
Stress/pressure is greater than internal strength, rock fractures and moves.
What is dip?
The angle at which the strata lie.
What rock characteristics produce steep cliff profiles?
Uniformed horizontal strata
What rock characteristics produce overhanging cliffs with unstable tops?
Rocks dip gently towards sea with almost vertical joints.
What rock characteristics produce a steep slope towards the sea?
Steep dip towards the sea (susceptible to rock slides).
What rock characteristics produce stable, steep cliffs?
Rocks dip inland
What rock characteristics form rough slopes towards the sea?
Rocks dip inland d with well developed joints at right angles to bedding planes.
Explain the formation of a cove on a concordant coastline.
River flows overland into sea.
River cuts valley, exposing weaker soft rock behind hard rock layer.
Erosion on weaker rock forms small cove.
Continued erosion produced semi-landlocked cove (hard rock erodes much slower).
Explain the formation of a Dalmatian coastline on concordant coastlines.
Valleys and ridges inland run parallel to coastline due to alternating hard/soft rock types. Sea level rise and land floods. Tops of ridges remain above sea level - now islands.
Give the best example of a Dalmatian coastline.
Croatian coastline (Adriatic Sea - Mediterranean). >1000 islands, limestone cliffs and coves = tourism.
Explain the formation of half coastlines on concordant coastlines.
Large amounts of sediment from a river settle in specific shallow ridges along a coastline. Stabilised by vegetation and forms an island/spit. Separates lagoons from the ocean.
Give an example of a haff coastline.
South coasts of the Baltic Sea - Poland, Lithuania.
Give an example of a coastal igneous rock and its erosion rate and permeability.
Granite. 1mm per year. Impermeable.
Give an example of a coastal sedimentary rock and its erosion rate and permeability.
Limestone/chalk. 2.5cm per year. Permeable (porous).
Give an example of a coastal metamorphic rock and its erosion rate and permeability.
Gneiss/marble. Almost entirely resistant. Impermeable.
Give an example of coastal unconsolidated material and its erosion rate and permeability.
Boulder clay. 1m per year. Very permeable.
How does vegetation stabilise sandy coastlines?
Roots bind sediment (less erosion). Reduce wind speed at ground level (less erosion more deposition). Dying plants add organic matter to sand - soil.
What is plant succession?
The way in which the vegetation on a sandy coastline changes over time influencing sand dunes and/or salt marshes.
What are pioneer species in reference to sand dune succession?
The initial plant species that colonise bare sand. Adapted to harsh conditions (e.g salt tolerant). Bind sand to form embryo dunes. Examples: sand couch, sea rocket.
What is the role of creeper plants in plant succession on sand dunes?
Creeper plants with leaves improve soil qualities of the sand by providing shade and binding qualities. Allows less adapted plants than pioneer species to colonise.
What is the role of marram grass in the second stage of sand dune plant succession?
Form yellow dunes by binding more sand by roots. Highly adapted - limited transpiration. Causes salt content to decline (rainwater removes salt content).
What is the name for the next-most-developed sand dune after yellow dunes that have less harsh conditions and can support a wider range of species?
Grey dunes / mature dunes.
What is a climactic climax community?
A local ecosystem of plants and animals that, through plant succession and development of vegetation, have reached a steady state.
What are waves caused by?
Friction between the wind and the sea surface.
What happens to a wave as it approaches the coastline (regular deep-shallow gradient)?
Velocity decreases and wave height increases.
Describe nearshore depth of destructive vs constructive waves.
Destructive deeper. Constructive shallower.
Compare beach profile of constructive vs destructive waves.
Destructive - steep shingle
Constructive - gently sloping sand
Compare frequencies of constructive and destructive waves.
Destructive: 13-15 per minute
Constructive: 6-8 per minute
Compare the type of movement within the wave in constructive and destructive waves.
Destructive - circular (deep + tall waves)
Constructive - elliptical (shallow + flatter waves)
Compare beach profiles of summer and winter beaches.
Summer (constructive): deposition at top of wave/beach forms berms. Steeper beach profile overall
Winter (destructive): backwash transports sediment offshore to form offshore bar. Shallower profile overall.
What is abrasion and attrition?
Attrition - rocks, sediment, pebbles hit each other to become smaller and more rounded.
Abrasion - destructive waves pick up this stuff and hit it against the cliff causing erosion.
Name the erosional landforms on a headland.
Crack, cave, arch, stack stump
Name an example of a wave-cut platform.
Lyme Regis (Dorset). Layers of limestone and shale eroded.
What are the 4 forms of marine transportation of material?
Traction (roll), saltation (bump/bob), suspension, solution.
Describe process of longshore drift.
Wave washes up beach at angle with prevailing wind. Backwash pulls back perpendicular to coastline. Net effect is lateral shift of material. Destructive waves (removes sediment) erode beach.
Describe the formation of a spit.
Dominant LSD direction. Gap in coastline (estuary/bay). LSD causes sediment to still be carried a short way then be deposited. Narrow strip of land forms. If estuary: flow prevents further deposition + split ends (double spit = spit on other side also ends). If bay: spit may continue to other end to form barrier beach / bar. Recurve spit due to tides, river current, wind direction change. Salt marsh forms behind.
What are the two types of deposition?
x - sediment in a salt marsh binds together and settles
y - sediment settles because gravity exceeds kinetic energy of the particles
Describe beaches and their depositional landforms.
Temporary store in sediment cell / coastal system. Berm - sediment deposited in same place at top of constructive waves. Beach cusp - waves that break at an angle are bent and have energy focused in certain areas, forming ‘small hills’ of sand along the beach. Storm ridge - extreme berm formed higher up the beach during a storm.
How do offshore bars form?
Destructive waves break before beach. Waves scour seabed and beach, deposit material offshore in a heap. + currents supplying sediment.
How do tombolos form?
Lower wave energy between a small offshore island and the mainland allows deposition. Sand and shingle forms beach/ridge between. May be covered at high tide.