geography p2

• geology


  the study of the structure and substance of rocks
• glacial processes: erosion


  plucking – freezing onto the surface and removing sediment abrasion – embedded sediment scouring the valley floor and sides
• glacial processes: weathering


  freeze-thaw – water freezing into cracks in the rock, expanding and

  splitting the rock apart deposition – sediment put down as a glacier retreats creates

  outwash till in the valley floor, and moraine at the snout and edges of

  the glacier.
• glacial processes 


  These processes combine to create distinctive characteristics of upland (areas with more resistant igneous and metamorphic rocks, creating U-shaped valleys and scree slopes) and lowland landscapes (areas with less resistant sedimentary rocks creating dip slopes and escarpments).
• • Sedimentary rocks 


  are small, eroded particles/remains of plants and

  animals deposited in layers that turn into rock over time and under

  pressure, for example, chalk, carboniferous limestone, clay.

  • The layered structure creates lines of weakness between layers.

  • Sedimentary rocks consolidate over time, so younger rocks are less

  consolidated and therefore less resistant to weathering and erosion.
• Igneous rocks


  are formed by heat, for example, cooling magma, which

  creates granite.

  • They are extremely resistant to erosion.
• Metamorphic rocks 


  are formed from existing rock changing shape and

  characteristics through heat and/or pressure, for example schists (a

  compressed mudstone) and slates (a compressed shale).

  • They have a layered structure and have faults which can be more

  readily eroded.
• Igneous and metamorphic rocks are found in the north and west of

  the UK (Scotland and Wales) due to past tectonic processes.

  • This created upland areas such as Cambrian Mountains and

  Grampian Mountains.
• Isolated areas of igneous and metamorphic rocks in the South West

  have created small scale landforms such as those found on Dartmoor

  and Bodmin Moor.
• Occasionally, harder sedimentary rocks (for example, carboniferous

  limestone (formed 250-350 million years ago) also form upland such as

  the Pennines.

  • Sedimentary rocks are found in the south and east of England such

  as The Fens, Norfolk Broads and the Somerset Levels.
• Upland area landscapes


  • U-shaped valleys caused by the movement of glaciers. They pluck

  rocks from the valley sides, and freeze-thaw weathering eventually

  provides more angular sediment which embeds into the glacier. This

  means that the moving glacier with embedded rocks causes the

  deepening of the valley floor and widening of the valley sides by

  abrasion.

  • hanging valleys caused by glacial erosion and later post-glacial rivers

  • scree slopes caused by slope processes and freeze-thaw

  • outwash plains caused by glacial deposition

  • misfit streams caused by post-glacial rivers.
• lowland areas landscape


  Warmer climates have better growing conditions, greater

  levels of vegetation and support more diverse ecosystems including burrowing animals.

  • dip slopes (gentle slopes)

  • escarpments (steep slopes)

  • low clay vales.
• human activities- upland 


  (less suitable for many human activities due to

  climates) settlements are smaller, found in flat valley bottoms, and

  typically use locally sourced materials, such as slates.

  • The landscapes include coniferous forestry and hill sheep pastoral

  farming..

  • People use these landscapes for drystone walled hill sheep farming,

  large-scale forestry and forest clearances, and tourism, such as skiing

  in Scotland, and climbing.
• human activity-lowland


  settlements formed on spring-lines of hillsides and along flatter plains.

  • Forestry is often deciduous, or orchards, which are used as walking

  and public areas.

  • Agriculture is usually arable (crops), as the climate is more temperate.

  This means that there is a longer thermal growing season, creating

  higher crop yields.

  • There is also less soil erosion, more fertile land, and larger and flatter

  sites which mean tractors and other machinery can be used.

  • In the south and west of the UK, there is also likely to be market

  gardening due to warmer climates
• discordant+Concordant coastlines

  condordant-(rock layers parallel to the coast) have a harder, more

  resistant outer layer protecting softer, less resistant rock inland. Once the more

  resistant rock is broken through the layer of less resistant rock is eroded more

  rapidly creating a crescent shaped cove. discordant-(alternating rock types at right angles to the coast) have

  different erosion rates.
• dis+concordant coastlines


  This creates headlands (areas of harder rock sticking out into the sea)

  and bays (the area of softer rock eroded away).

  • As a headland erodes (due to faults and joints in the rocks becoming

  exposed to marine and sub-aerial processes), other landforms are

  created.

  • Faults and cracks in the rock are widened by abrasion, hydraulic action,

  wave pounding and solution.

  • These faults and cracks create caves, eventually breaking through the

  headland creating an arch, then a stack (as the arch collapses) and a

  stump.
• • Soft rock coastlines often suffer from mass movement (for example,

  landslips/rotational slumping as seen in Holderness).

  • Harder rock coastlines erode by the cliff foot being eroded between the

  high and low water marks, causing a wave cut notch.

  • Over time, the cliff is undercut and the unsupported cliff face collapses.

  • The cliff retreats inland leaving a flat rocky area visible at low tide which

  is a wave cut platform.
• Seasonality (different seasons have different climates/weather conditions)

  • In the UK Autumn and Winter are the wettest and often have the most

  storms, which creates low pressure systems and higher waves, leading

  to more rapid coastal retreat.
• Storm frequency (how often we have storms)

  • More storms create higher winds and lower pressures which then

  creates larger, more powerful waves which erode the coastline more

  rapidly.
• Prevailing winds (dominant wind direction)


  • The longer the fetch (the distance over which wind acts on the surface

  of the water), the more destructive the waves are. For example, in the

  UK, the west coast has the largest fetch with south-westerly prevailing

  winds.
• • Marine processes are actions caused by the sea.

  • Destructive waves are high in height, frequency and have a stronger

  backwash than swash. This removes both the beach material (creating

  narrow, steeply sloping beaches) and materials at the cliff foot

  increasing coastal retreat.
• Sub-aerial processes are actions occurring above sea level.

  • They act on the cliff face after the waves have undercut the bottom of

  the cliff.

  • They lead to mass movement (large scale movement of sediment

  usually downslope)
• sub aerial processes-mass movement examples

  o Rock falls (weathered areas undercut, unsupported areas

  collapse),

  o Slumping (after long periods of rain, rainwater seeps through

  soil and permeable rocks, it then meets a layer of impermeable

  rock and then the saturated rock slumps and slips, often in a

  rotational matter along a curved surface),

  o Sliding (the movement of a large amount of material along a flat

  surface for example, a bedding pain).
• sub aerial processes 


  have a major impact upon coastal landforms,

  particularly cliffs and headlands.

  • In addition, such movements of material are one source of beach

  material (in addition to riverine and offshore sources).
• Weathering is the breakdown of rocks on or near the surface. It can be:

  • mechanical – freeze-thaw splitting the rock apart

  • chemical – salt corrosion and acid rain solution on limestone cliffs

  • biological – plants and burrowing animals and nesting birds weaken

  clifftops and cliff-faces
• Transportation


  The movement of material by solution, suspension, saltation and traction
• Deposition


  The putting down of material
• Transportation and deposition help to create coastal landscapes
• Coastal landscapes created by transportation and deposition


  • Spit
  • Bar across an estuary with a lagoon
  • Tombolo connecting to an island
• Longshore drift


  1. Transports sediment along the beach in a zig-zag movement due to prevailing winds and wave action

  2. The swash pushes sediment up the beach at an angle

  3. The backwash drags sediment back down the beach at a right angle
• Longshore drift transporting sediment


  Continues until sediment is deposited on the seabed due to a change in the direction of the coast
• Gradually sediment builds up to form a spit, a bar across an estuary with a lagoon, or a tombolo connecting to an island
• deposition


  • Constructive waves built up beaches through greater swash than backwash, causing sediment to build up on the beach. • These beaches are often wide and gently sloping.
• Fieldwork link

  • Coastal processes can be investigated through measuring beach profiles. A beach profile is a cross section of the beach measured from the sea to the cliff base/land which helps you investigate the beach’s morphology (shape). • A narrow, steeply sloping beach is likely to be experiencing destructive waves. • A wider, gently sloping beach is likely to be experiencing constructive waves (or beach replenishment – adding sediment).
• Millions of people and jobs are dependent on the UK coastline
• Important infrastructure located on the UK coastline

  • Roads and railways
  • Oil refineries
  • Chemical plants
  • Ports
• The coastline is often defended (direct effect) due to their importance
• Construction removes sand and gravel from the coastal zone (dredging) thus causing change in the sediment budget, which then causes erosion later or further downdrift (indirect effect)
• Agricultural areas are often the most severely affected as they are less valuable and therefore less likely to be defended
• Agricultural areas are often left as part of managed retreat or are in areas of 'do nothing'