What influences the landscapes of the UK?

• Geomorphic processes

  • the methods involved in changing the shape of the landscape.
• Weathering

  • the break down of rock in its place of origin.
• Mechanical physical weathering

  • temperature changes cause rocks to break down.
  • also called freeze-thaw.
  • happens in places where night temperatures often reach below freezing.

  
• Biological weathering

  • rock breakdown due to action of plants and animals.
  • nestling birds and small burrowing animals like rabbits can also cause rock to breakdown through biological weathering.

  
• Chemical weathering

  • rock decomposes due to chemical reaction
  • carbonation, rain is slightly acidic and reacts with limestone causing them to dissolve.
  • oxidation, iron minerals in the rock react with the air to cause rust and breakdown the rock.
  • solution, salt minerals in the rock are dissolved.
• Weathering in the UK

  • the UK's climate is considered to be temperate so physical weathering of the UK's landscape is usually slow.
  • areas that receive more precipitation and fluctuations in temperature such as the mountains of Wales and Scotland see higher rates of weathering.
• Mass movement

  • the downhill movement of material under the influence of gravity.
  • type of movement is influenced by the angle of the slope, nature of regolith, amount of type of vegetation, water, type and structure of rock, human activity, climate.
• Types of mass movement

  • soil creep, slow process, common in humid climates, due to expansion from freezing, moisture or heat, followed by gradual downward settling when the soil shrinks.
  • flow, occurs on slops 5 to 15 degrees, after saturation from surface water flow, often flattening and carrying away vegetation.
  • slide, movement of material which remains together until the bottom.
  • fall, rapid movement on steep slopes caused by extreme weathering which destabilise rocks and trigger slope collapse.
  • slump, large section of land moving down the slope in one piece leaving behind a curved surface.

  
• Erosion

  • process by which water breaks down rock and sediment from rivers and coasts.
• Hydraulic action

  • the sheer force of water compresses air into cracks that expand and fracture over time.
  • in rivers this is seen along the banks and beds and causes vertical erosion in the upper part of a river and lateral erosion the the banks in the lower course.
  • on coasts it is when waves smash against the cliff face.
• Abrasion and corrasion

  • sediments, rocks or pebbles grind against a rivers bank, bed, shoreline or cliffs in a sand papering effect.
  • responsible for a rivers lateral and vertical erosion.
  • angular rocks are more effective at grinding.
• Corrosion and solution

  • all water is slightly acidic and dissolves soluble rocks such as limestone or chalk, and carry the dissolved material away leading to erosion.
• Attrition

  • sediment particles knock against each other and break into smaller more rounded pieces.
  • in rivers this action occurs along the river bed and within the water.
  • on coasts rocks and stones carried by waves hit and knock against each other wearing them down into rounded pebbles on the beach.
• Impacts of erosion

  • these processes can interact with each other leading to complex erosion.
  • erosion has significant environmental, economic and social impacts such as loss of habitat, damage to infrastructure and increased risk of flooding and storm damage.

  
• Transportation

  • material in rivers and the sea arrives from many sources such as being eroded from cliffs and river banks.

  
• Longshore drift

  • the main process of deposition and transportation along the coast.
  • influenced by prevailing winds, waves approach the beach at an angle.
  • as the wave breaks the swash carries material up the beach at the same angle.
  • as the swash dies away, the backwash carries the material down the beach at right angles.
  • the process repeats, transporting material along the beach in zig zag movements.

  
• Deposition

  • sediment is dropped and occurs when a river or the sea loses energy.
  • sediment that is carried by rivers can be deposited at the coast or on the inside of a river bend.
  • constructive waves deposit material at the shoreline to build the beach.
  • the heaviest material is deposited first known as the load.
  • the lighter materials like gravel, sand and slit are known as alluvium and carried at a distance.
  • dissolved materials are carried out to sea.
• Conditions for deposition

  • in a river, a lack of precipitation will reduce a rivers overall charge, decreased gradient, slower flow on the inside of a river bend, when the river enters a sea.
  • along the coast, too much material in the water, too little wind, waves enter a sheltered area like a bay and form beaches, waves enter shallow water.
• Coastal landforms erosion

  • wave action is that waves are marine processes that erode, transport and deposit material.
  • destructive waves erode the beach, they have a short wavelength, high frequency rate and a steep wave gradient, responsible for the majority of coastal erosion.
  • constructive waves are beach builders, they have a long wavelength, low frequency rate and a shallow wave gradient, the swash is stronger than its backwash, which carries material up onto the beach and deposits it.

  
• Headlands and bays

  • occurs when there are alternating bands of hard and soft rock, a discordant coastline.
  • the soft rock is eroded backwards forming an inlet which curves inwards and a bay is formed.
  • the hard rock is left protruding out to sea as a headland.
  • headlands usually feature cliffs along its sides, projects out to sea, usually longer than it is wide, geology is of resistant rock.
  • a bay usually has a wise open entrance from the sea, a roughly semi circular shape extending into the coastline, land that's lower than the headlands surround it, may or may not have a beach.

  
• Cliffs and wave cut platforms

  • soft rock erodes quickly and will form sloping cliff faces.
  • steep cliffs are formed where there's hard rock facing the sea.
  • a wave cut platform is a wide gently sloped surface found at the foot of a cliff.
  • the sea hits the base of the cliff, forming a wave cut notch.
  • abrasion, corrosion and hydraulic action further extend the notch back into the cliff.
  • undercutting leads to instability and collapse of the cliff.
  • backwash of the waves carries away the eroded material leaving behind a wave cut platform.
  • the process repeats and the cliff continues to retreat.

  
• Caves and arches and stacks

  • as waves approach the shore their speed reduces and this causes wave refraction.
  • this refraction erosional process of hydraulic action, abrasion and corrosion attack weaknesses in the headlands.
  • as a crack widens abrasion begins to wear away at the forming cave that will become larger and eventually break through the headland to form an arch.
  • the arch continually becomes wider and tinner through erosion below and weathering above, eventually the roof collapses leaving behind a stack which can be undercut at the base and collapse to form a stump.

  
• Beaches

  • beaches form in sheltered areas such as bays through deposition via constructive wave movement, where the swash is stronger than the backwash.
  • constrictive waves carry sediment up the beach, the largest material deposited along the upper reach of the swash.
  • as the backwash moved back down it loses energy meaning the deposition of sediment gets smaller.

  
• Spits

  • an extended stretch of sand that extends out to sea from the shore that occurs when there is a change in the shape of the coastline.
  • sediment is transported by longshore drift and due to increased friction more deposition occurs.

  
• Bars

  • when a spit grows across a bay and joins two headlands together a bar of sand is formed.

  
• River long profile

  • long profile of a river shows the changes in the river gradient from the source to the mouth.
  • most long profiles have a concave shape.

  
• River cross profiles

  • cross profiles of a river are cross sections from one bank to another.
  • cross profiles of upper, middle and lower course show the change in the river channel.
• Upper course

  • shallow, steep valley sides.
  • narrow, low velocity.
  • large bedload.
  • rough channel bed.
  • high levels of friction.
  • vertical erosion.

  
• Middle course

  • deeper than upper course channel.
  • gentle valley sides.
  • wider than upper course.
  • greater velocity than upper course.
  • material in river decreases in size.
  • smoother channel bed.
  • lower levels of friction than upper course.
  • lateral erosion.

  
• Lower course

  • deeper than middle course channel.
  • flat floodplains.
  • wider than middle course.
  • greater velocity than middle course.
  • material carried mainly sediment and alluvium.
  • smooth channel bed.
  • lowest friction.
  • deposition is dominant.

  
• V-shaped valleys

  • vertical erosion is dominant in the upper course of the river.
  • this cuts down into the river bed and deepens the river channel.
  • weathering and mass movement leads to material from the valley sides collapsing into the river forming a steep V-shaped valley.

  
• Interlocking spurs

  • in the upper course the channel starts to meander and erosion happens on the outside of the bend.
  • in the upland areas this forms interlocking spurs.

  
• Waterfalls and gorges

  • the soft rock erodes quicker, undercutting the hard rock and creating a plunge pool.
  • this leads to the development of an overhang of hard rock which eventually over time collapses.
  • the overhang falls into the plunge pool increasing abrasion and making the pool deeper.
  • this process repeats and the waterfall retreats upstream leaving a steep sided gorge.

  
• Meanders

  • in lowland areas lateral erosion is dominant as the gradient lessens and water begins to wander across the land leading to meanders.
  • the fastest flow is on the outside of the rive bend leading to erosion which undercuts the riverbank forming a river cliff.
  • the slowest flow is on the inside of the river bends leading to deposition which forms a slip-off slops.

  
• Oxbow lake

  • the erosion on the outside bends can eventually lead to the formation of a meander neck.
  • the river may cut through the neck of the meander, forming a straighter course for the water.
  • the meander becomes cut off from the main river channel forming an oxbow lake.

  
• Floodplains and levees

  • floodplains are flat expanses of land either side of the river.
  • high discharge may cause the river to overflow the banks and more of the water is in contact with the land surface as the water spreads across the floodplain.
  • the heaviest material is deposited first nearest to the river channel forming natural levees.

  
• Coastal case study the Dorset Coast

  • the Dorset coast has both erosional and depositional landforms.
  • it has bands of sedimentary rock, consisting of soft clay and harder limestone and chalk.
  • these rocks erode at different rates.
• Rock formation along the Jurassic Coast

  • Triassic period, 250-200 million years ago, rocks such as limestone were formed in desert conditions.
  • Jurassic period, 200-140 million years ago, sea levels were higher and layers of sedimentary rocks formed such as clay and limestone.
  • Cretaceous period, 140-65 million years ago, sea levels fell and rose, depositing more sedimentary layers such as chalk.
  • Quaternary period, 2.6 million years to present, after the last ice age 10,000 years ago, sea levels rose again and the processes of erosion and deposition have created the modern coastline.
• Erosional landscape Durdle Door

  • Durdle Door is an example of an arch formation.
  • wave erosion opened a crack in the tough limestone headland.
  • further erosion led to a cave which has developed into an arch in the headland.
  • softer rocks behind the limestone have been washed away leaving an eroding line of chalk cliffs by mechanical, chemical and biological weathering.
• Erosional landscape Lulworth Cove

  • Lulworth Cove is a small bay that has formed when a gap was eroded in the band of tough limestone.
  • lying behind this limestone is a band of soft clay and has been eroded to form a bay.
  • the limestone cliffs forming the back wall of the cove are vulnerable to mass movement and sometimes experience small slides and slumps.