3.2

• What is Erosion?

  The wearing away of the earths surface by the mechanical weathering process of glaciers, wind, rivers, waves.
• What is Fetch?

  The distance of open water which wind travels uninterrupted, determining the size and energy of waves reaching the coast.
• What is mass movement?


  The movement of material downhill influenced by gravity and can be assisted by rainfall.
• What is weathering?


  The breakdown of rock which remains in situ.

  Can be mechanical, biological/organic or chemical.
• What are the 3 sources of energy at the coast?


  Wind, Waves, Tides and currents.
• Wind


  Prevailing wind determines the direction of movement of sediment,

  Spatial variations in energy result from variations in the strength and direction of wind,

  Wind plays a role in the formation of waves,

  Acts as an agent of erosion/can pick up and remove sediment transporting it down the coast.
• What is wave height or amplitude?

  The high difference between the crest and trough of a wave.
• What is Wavelength?


  Distance between 2 crests
• What is Wave Period?


  The time it takes one wave to travel the distance of one wavelength.
• How do waves form and break?


  Friction with the seabed causes the base of the wave to slows down,

  increasing the height and steepness of the wave until the upper part plunges and the wave breaks.
• What is backwash?


  Water returning back down the beach to the sea
• What are constructive waves?

  Wave with a low height, long wavelength and low frequency.

  There swash is more powerful than there is backwash so material is deposited.
• What are Destructive waves?

  Waves with a high wave height, steep form and high frequency.

  The backwash is stronger than swash so sediment is eroded.
• what is swash?


  rush of water up the beach after a wave breaks.
• What is an example of negative feedback (constructive and destructive cycle)?


  Constructive waves build up the beach,

  This makes the gradient of the beach steeper so it encourages destructive waves,

  Destructive waves move material back to the sea,

  So the beach has a more gradual gradient and the pattern repeats.
• What is wave refraction?


  Waves refract when they reach an irregular coastline (e.g Headland) and become increasingly parallel to the coastline.

  This is because as waves reach shallow water(around a headland) they slow down and the waves in deeper water move faster causing wave energy to bend and become concentrated on the headland leading to increased erosion on the headland and increased deposition in the bays.
• What is a current?

  Permanent or seasonal movement of surface water in the seas and oceans.
• What are the 3 different currents?

  Longshore currents, Rip currents and upwelling
• What are longshore currents?

  Most waves hit the coastline at an angle generating a flow(currents) running parallel to the shoreline.

  It moves water along the surf zone and transports sediment parallel to the shoreline.
• What are rip currents?

  Strong currents moving away from the coastline that develops when seawater is pilled up along the coastline by incoming waves.

  Initially the current may run parallel to the coast before flowing out the breaker zone.

  They are dangerous to swimmers and small boats.
• What is upwelling?


  The movement of cold water from deep oceans towards the surface.

  more dense cold water replaces warm surface water creating nutrient-rich, cold ocean currents.
• What is a Tide?


  The periodic rise and fall of sea levels caused by the gravitational pull of the sun and moon.
• How does the moon control the tides?

  The moon pulls water towards it, creating a high tide causing a compensatory bulge on the opposite side of the earth.

  When the moon orbits the earth the tide follows it.
• What is spring tide?

  Highest monthly tidal range when the sun, moon and earth are in a straight line.
• What is neap tide?

  Lowest monthly tidal range when the moon and sun are positioned at 90 degrees perpendicular to each other.
• What is the Tidal range?


  The difference in height of the sea water at low and high tide
• What does tidal range determine?

  The upper and lower limit of erosion and deposition, the amount of time each day that the littoral zone is exposed and open to sub-aerial weathering.
• What is a storm surge/tidal surge?

  Meteorological conditions give rise to strong winds which produce much higher water levels than those at high tides.

  Depressions produce low pressure conditions that help raise sea level.

  Strong winds push waves up the coastline.
• What is a coastal sediment budget?

  The balance between sediment being added and removed from a coastal system.

  it is defined with each sediment cell
• What is a high energy coast?

  A coastline where strong, steady prevailing winds create high energy waves and the rate of erosion is greater and the rate of deposition.
• What landforms would you see at a high energy coastline?

  headlands, cliffs and wave cut platforms
• What is an example of a high energy coastline?

  The North Cornish coast in south west England.
• What is a low energy coast?

  A coastline where wave energy is low and the role of deposition often exceeds the rate of erosion of sediment.
• What are some examples of low energy coasts and landforms you would find there?

  Spits, beaches.

  e.g Estuaries, inlets and sheltered bays
• What is a sediment cell?

  A distinct area of coastline seperated from other areas by well defined boundaries (headlands and stretches of deep water)

  Are regarded as closed sytems
• What are some sources of sediment?


  Streams and rivers,

  Esturies,

  Cliff erosion,

  Offshore sandbanks,

  Shells and coral fragments.
• What does calculating a sediment budget require?

  Identification of all the sources and sinks and an estimation of how much is added and taken away.
• What are marine processes?

  Processes that operate upon a coastline and are connected with the sea. e.g tides, waves and longshore drift
• What are sub-aerial processes?

  Processes that slowly break down a coastline, weakening the underlying rocks and allowing sudden movements or erosion to happen, leaving material in situ.
• What are 4 marine erosion processes?

  Hydraulic action, Wave quarrying/Cavitation, Abrasion/corrasion and attrition.