coastal landscapes and change

• cliff profile

  the shape and charcateristic of a cliff often viewed as a cross section
• coastal morphology

  the shape and form of coastal landscapes and their features
• coastal plain

  an area next to the sea which has low + flat relief
• coastal recession

  another word for coastal erosion
• constructive wave

  a low suring wave with a strong swash that surges up a becah often forming a berm
• destructive wave

  a high plunging wave that crushes onto a becha and has a powerful backwash so sedminet is pulled back towards the sea
• dip

  the angle at which rock strata lies eg vertically or horizontally
• faults

  fractures in the rock formed when the stress/pressure to which a rock is subjected exceeds its internal strengh
• folds

  bends in the rock strata formed by pressure during tectonic activity which makes rocks crumple
• high energy enviroments

  coastlines with powerful waves where rates of erosion exceeds rates of deposition
• joints

  vertical cracks in the rock casued by contraction as sediments dry out or by earth movements during uplift
• lithology


  physical characterictics of particular rocks
• littoral zone

  boundary between land and sea ehich streches out into the sea and onto the shore. the zone is always changing due to dynamic intercation between processes occuring in seas, oceans and lands
• low energy enviroments

  coastlines with waves of relativly low power where rates of deposition exceed rates of erosion
• the coastal zone

  is a zone of transition in which sea changes to land. it consits of onshore (60km inland) and offshore (370km sea).
• the coast as a system

  any change to a particular element impacts the rest of the system.

  - inputs: marine, atmospheric, land, people

  - proccesses: weathering, mass movement, erosion, transport, deposition,

  -outputs: erosional landforms, depositional landforms, different types of coasts
• the littoral zones 4 sections

  1. backshore: above the influence of waves except during high tides or storms. large material breaks of into angular shapes.
  2. foreshore: intertidal or surf zone
  3. near shore: breaker zone
  4. offshore: beyind influence of waves
• how are coasts classified

  although no classification system is difinitive

  1. geology
  2. level of energy
  3. balance between erosion and deposition
  4. changes in sea level
• what is a fetch

  the distance between 2 peices of land. determines wind.
• the west coast of the uk

  subject to storms and large waves due to the fetch across the atlantic and the low weather systems which form here. This side of the UK tends to be a high energy coastline.
• The east coast of the uk

  tends to be lower energy enviromnet levels here because of less destructive waves and more material deposited.
• the Tees to Exe line

  bellow the Tees to exe line: softer less resistent sedimentary rock

  above the Tees to exe line: harder more resistant rock eg igneous and metamorphic
• what factors determine the morphology of a coastline

  1. the geology and lithology
  2. the relief annd slope
  3. the rock type
  4. permability of the rock
  5. resistance to erosion
• igenous rock characteristics

  • types : granite/basalt
  • ersoion rate: very slow <0.1cm per yr
  • structure: interlocking crystals allowing high resistance
• metamorphic rock charcteristics

  • types: slate/marble
  • rate of erosion: slow 0.1-0.3cm per yr
  • structure: crystal all orientated in the same direction
• sedimentary rock charcteristics

  • types: limestone
  • rate of erosion: very fast 0.5-10cm per year
  • structure: lots of fractures and bedding planes making them weak
• types of lithology

  • strata: layers of rock
  • bedding planes: natural breaks in the strata caused by gasps in time during periods of rock formation
  • joints
  • folds
  • faults
  • dips
• types of relief (cliff profiles)

  • horizontal strata produce steep cliffs
  • rocks dip gently towards the sea with verticle joints
  • steep dip towards the sea
  • rocks dip inland producing a stable, steep cliff profile
  • rocks dip inalnd but with well developed joints at right angles to bedding planes
• weathering definition

  the gradual break down rock at or close to the grains surface. its divided into 3 types:

  1. mechanical
  2. biological
  3. chemical
• by breaking rock down weathering creates sediment which the sea can then use to erode the costs and increases rate of erosion.
• types of mechanical weathering

  • freeze thaw weathering
  • salt weathering
  • setting and drying
• freeze thaw weathering

  occurs when water enters a crack/joint in the rock when it rains and then freezes in cold weather. When water freezes it expands by 10% creating pressure on the rock forcing the cracks to widen. the repetition causes rocks to break away and collect as scree. These rocks are picked up by the sea and used for erosion.
• salt weathering

  water evaporates leaving behind crystals which grow and excert stresses on the rock causing it to split. salt also corrodes the rock
• wetting and drying

  rocks in clay expand when they get wet and contract when they dry. This causes them to crack and break up.
• biological weathering

  occurs in several ways

  1. plant roots grow in small cracks in a cliff face. These cracks widen as roots grow thicker breaking the rock
  2. water running through decaying vegetation becomes acidic causing increased chemical weathering
  3. birds + animals dig burrows into cliffs
  4. marine organisms burrow into rocks
• chemical weathering carbonation

  1. rainwater absorbs carbon dioxide from the air to form a weak carbonic acid
  2. this reacts with calcium carbonate in the rocks to form calcium bicarbonate which is easily dissolvable
  3. cooler the rainwater the more carbon dioxide absorbed
• hydrolysis

  when acidic rainwater breaks down rock causing it to rot
• oxidation

  when rocks are broken down by oxygen and water
• mass movement

  the movement of weathered material down a slope due to gravity
• mass movement processes

  classified in different ways: nature of movement, rate of movement, type of mass movement.

  the resultant movement depends on a range of factors:

  • angle of slope
  • vegetation cover
  • rock type and structure
  • how wet the ground is