Geography Coasts EQ1

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  • EQ1
    • Why are coasts dynamic?
      • Boundary between land and sea, marine and terrestrial processes operate and interact here
      • Coasts experience extreme events eg tropical cyclones
      • Human development on the coats is varied eg transport and industies
    • The littoral zone
      • From the highest sea level line to shallow offshore water.
        • Backshore: Above high tide level, is only affected by spring tides and during major storms
        • Foreshore: Wave processes are normally confined to between high and low tide marks
        • Nearshore: Shallow water close to land, area of high human interactivity. It transfers sediment by currents close to the shore
      • Zone of dynamic equilibrium: inputs of sediment from sea and rivers, waves causing erosion and deposition, tidal ranges, offshore currents, LSD and human activities
    • Holderness Coast Casestudy
      • Over 30 villages gone, Britain's fastest eroding coastline, cliff made from boulder clay
      • Roads submerged, loose electric cables and water pipes
      • Erosion rates of 30ft a year, in 35 years, 60m of cliff eroded.
      • Groynes built from Norwegian rocks but they don't protect the south
      • Old sea defenses used, local council are investing in new sea walls for 1 km of beach and granite boulders from Norway
    • Coasts as a system
      • Inputs: Marine - waves, tidal. Atmospheric - solar/wind energy, climate change. Terrestrial - tectonics, rock types, geology and gravity. People - management and tourism.
      • Processes: Erosion - abrasion, corrosion, hydraulic power and attrition. Weathering - sub aerial and mass movement
      • Transport: Transefer of energy and material eg. LSD
      • Deposition: Due to a reduction in energy eg. sheltered bays
      • Outputs: Erosional - cliffs, WC platfroms and notches, headlands and bays,CASS. Depositional - beaches, spits, deltas, salt marshes and mangroves. Others - types of coasts, material deposited into sea.
    • Types of coastlines
      • High energy/ rocky coastlines
        • Destructive waves, storm conditions, long fetches
        • Erosion and transport, sediments from eroded land and MM
        • Cliffs, WC platforms, CASS
        • Exposed to large waves, high/low land coasts
        • Atlantic coast of Norway and Scotland. Pacific coast of Alaska
        • Cliff profiles: 1. Marine erosion, cliffs are steep, vegetated and little rock debris. 2. Cliffs not directly eroded at base tend to be curved. Sub aerial processes move sediment downhill, little marine influence means debris is not removed
      • Low energy/ coastal plains
        • Constructive waves, calm conditions and short fetch
        • Deposition and transport, sediment from rivers and LSD
        • Beaches, spits, saltmarshes, sand dunes, bars and mudflats
        • Sheltered from large waves, lowland coasts
        • Med sea and East Anglia
        • Formed in two ways: 1, sea level fall exposing the sea bed 2. deposition of sediment from land causes coastal accretion, where the coastline gradually moves forwards
    • Geology
      • Igneous: magma cools under the surface = intrusive igneous rock, magma cools on the surface after an eruption = extrusive igneous rock. Very slow erosion rate, few joints, crystalline rocks,
        • Eg. granite, basalt. Tuff, obsidian and pumice
      • Sedimentary: sediments accumalates over time and deposits in layers, these layers become squeezed and compressed into a rock. Quite fast, lots of fractures
        • Limestone, shale and sandstone
      • Metamorphic: Rock changed by extreme heat and pressure, formed deep under the earth or when rocks near the surface are heated up by the movement of tectonics or magma. Slow, crystalline rocks, often folded and fractured
        • Shale - Slate, sandstone - quartzite, limestone - marble
    • Lithology
      • The physical characteristics of particular rocks
        • Strata, bedding planes, joints, folds, faults and dips
    • Permeability
      • Permeable rocks allow water to flow through them eg. sandstones and limestones
      • Impermeable rocks do not allow groundwater flow eg, clays, mudstones and most igneous and metamorphic rocks
      • Permeability is important as groundwater can weaken rocks be removing the cement that binds sediment in rocks together
      • Groundwater can also create pore water pressure within cliffs which affects their stabilitity
    • Concordant vs Discordant
      • Concordant: altering layers of hard and soft rock that run parallel to the sea
      • Discordant: altering layers of hard and soft rock are perpendicular to the sea . The soft rock can become exposed if the hard rock is breached
    • Vegetation
      • Sand dunes: plentiful supply of sand, large area, onshore winds and obstacles to trap sand eg. vegetation
        • Embryo dunes, fore dunes, yellow dunes, grey dunes, slacks and Pine woodlands
      • Saltmarshes: Tidal conditions bring sea water in and out and rivers bring fine silts and muds and deposits them at the side of an estruary

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