Section C

Upland areas

• north and west of the country

• Formed of hard igneous or metamorphic rock

• E.g. Scottish Highlands, northern Wales

Lowland areas

• south and east

• Softer, sedimentary rocks that erode more easily (e.g. chalk and clays)

Where are most cities

• in lowland areas

• Often on the UK’s main rivers

• E.g. London (on the Thames)

River Clyde

• Upland

• wide lower valley

• Flood plain

• The City of Glasgow is situated on the flat ground of the Clyde’s flood plain

Grampian mountains

• part of the Highlands

• Home to Ben Nevis (highest mountain in the UK)

• Steep, rocky, sparsely populated

Lake district

• Upland area

• national park

• Very popular with tourists

• Lots of glacial features

Holderness coast

• made mainly of soft boulder clay

• Cliffs are eroding quickly

• This allows landforms such as the spurn head spit to form

Snowdonia

• glaciated upland areas Often on

• Formed from rock from an extinct volcano

• Steep mountains e.g. snowdon

• Glaciated valleys

Dorset coast

• bands of hard and soft rock

• Leads to landforms such as stacks, arches and spits

The Fens

• marshy, flat, low lying area

• Used to be larger but a lot of land has been drained for farming

Types of waves

• constructive

• Destructive

Destructive wave

• erode the coast

• High frequency

• High and steep

• Backwash is stronger than swash, so material is removed

Constructive wave

• Deposit material

• low frequency

• Low and long

• Swash is more powerful than backwash, so material is deposited

How are waves formed

• by the wind blowing over the sea

• This creates ripples with the surface of the water

• This creates friction which can then develop into waves

What is the fetch

• the distance over water which the wind can blow

• Longer = more powerful waves

Factors that affect wave strength

• strength of wind

• How long wind has been blowing for

• Length of the fetch

What is weathering

Breakdown of rocks in situ

Types of weathering

• mechanical

• Chemical

Mechanical weathering

• breakdown of rocks in without changing chemical composition

• E.g. freeze thaw weathering

Freeze thaw weathering

• happens when temperature alternates above and below 0 degrees

• Water enters cracks in rock

• When water freezes it expands, which puts pressure on the rock

• When the water thaws it contracts, which releases the pressure on the rock

Chemical weathering

• the breakdown of rock by changing its chemical composition

• E.g. carbonation weathering

carbonation weathering

• occurs in warm and wet conditions

• Rainwater has carbon dioxide dissolved in it, which makes it a weak carbonic acid

• Carbonic acid reacts with rock that contains calcium carbonate e.g. carboniferous limestone so the rocks are dissolved by the rainwater

mass movement

• the shifting of rocks and loose material down a slope e.g. a cliff

• Happens when force of gravity acting on a slope is greater than the force supporting it

Effect of mass movement on coasts

Causes them to retreat rapidly

when is mass movement more likely to happen

When the material is full of water (acts as a lubricant and makes material heavier)

What is created when material shifts

a scarp (steep cut in the side of the slope)

types of mass movement

• sliding

• Slumping

• Rock falls

Sliding

Material shifts in a straight line along a slide plane

slumping

Material rotates along a curved slip plane

Rockfalls

material breaks up, often along bedding planes and falls down a slope

Three processes of erosion

• hydraulic action

• Abrasion

• Attrition

hydraulic action

• sheer power of the water

• Crash against rocks, compresses air in the cracks

• Puts pressure on the rock

• Repeated compression widens the cracks and causes bits of rock to break off

abrasion

• sandpaper effect

• Eroded particles in the water scrape and rub against rock, removing small pieces

attrition

Eroded particles in the water collide, break into smaller pieces and become more rounded

How is material transported along the coast

longshore drift

longshore drift

• waves follow the direction of the prevailing wind

• Hit the coast at an oblique angle

• Swash carries material up beach in the same direction as the waves

• Backwash carries material down the beach at right angles to the coast

deposition

• occurs when water carrying sediment loses energy and slows down

• Coasts build up when the amount of deposition is greater than the amount of erosion

when is the amount of deposited material increase

• lots of erosion elsewhere on the coast so more material is available

• Lots of material is transported into the area

four other processes of transportation

• traction

• Saltation

• Suspension

• Solution

traction

Large particles like boulders are pushed along the sea bed by the force of the water

saltation

pebble sized particles are bounced along the sea bed by the force of the water

suspension

small particles like silt and clay are carried along in the water

solution

soluble materials e.g. limestone dissolve in the water and are carried along

Types of coastline

• concordant

• Discordant

how does rock type and geological structure influence the erosional landforms that develop on a coastline

• hard rocks like granite take a long time to erode, while softer rocks like sandstone erode more quickly

• Rocks with lots of joints and faults (cracks and weaknesses in the rock) erode faster

Concordant coastline

Alternating bands of hard and soft rock are parallel to the coast

discordant coastline

alternating bands of hard and soft rock are perpendicular to the coast

what forms along discordant coastlines

• headlands

• Bays

Differential erosion

hard rock erodes more slowly than the soft rock, so erosion occurs at different rates

Formation of headlands and bays

• Differential erosion occurs along a discordant coastline

• Erosion occurs mainly due to hydraulic action and abrasion

• Over time, the impact of this will be that areas of hard rock sticking out into the sea (becoming headlands), whilst the soft rock areas become set back (as bays or inlets)

• Once headlands and bays have been formed, the bays become low energy wave areas with deposition leading to the formation of beaches

• Headlands become a focus of erosion due to high energy waves where caves, arches, stacks and stumps are formed

Formation of cliffs and wave cut platforms

• The sea attacks the base of the cliff between the high and low water mark along a headland.

• A wave-cut notch is formed by erosional processes such as abrasion and hydraulic action.

• As the notch increases in size, the cliff becomes unstable and collapses, leading to the retreat of the cliff face.

• The backwash carries away the eroded material, leaving a wave-cut platform.

• Abrasion helps to make the wave cut platform smoother over time

• The process repeats. The cliff continues to retreat.

• Rock pools will remain where cracks and joints in the rock can be found and that fill with water when the tide is high

formation of caves, arches, stacks and stumps

• Firstly, the sea attacks the foot of the cliff and begins to erode areas of weakness such as joints and cracks, through processes of erosion such as hydraulic action, wave pounding, abrasion and solution.

• Gradually these cracks get larger, developing into small caves. Further erosion widens the cave and where the fault lines run through the headland, two caves will eventually erode into the back of each other forming an arch, passing right through the headland.

• A combination of wave attack at the base of the arch, and weathering of the roof of the arch (by frost, wind and rain), weakens the structure until eventually the roof of the arch collapses inwards leaving a stack, a column of rock which stands separate from the rest of the headland.

• The stack continues to erode, eventually collapsing to form a stump which may be covered by water at high tide. Credit wave refraction processes eg concentrating energy on headlands.

Beaches

• Beaches develop at the head, or innermost part, of a bay.

• In this area wave action is usually not very strong and deposition occurs.

• The beach will not extend to the headlands because erosion from waves increases strongly towards the headlands and deeper water.

• Longshore drift may cause material to be moved along the bay.

Spit formation

• Waves follow the direction of the prevailing wind. They usually hit the coast at an oblique angle.

• The swash carries material up the beach, in the same direction as the waves.

• The backwash then carries material down the beach at right angles, back towards the sea.

• Over time, material zigzags along the coast.

• Coastal deposition takes place in areas where the flow of water slows down, for example in sheltered bays and where there is a change in the direction of the coast.

• Spits form at sharp bends in the coastline, eg at a river mouth.

• Longshore drift transports sand and shingle past the bend and deposits it in the sea.

• Strong winds and waves can curve the end of the spit (forming a recurved end).

bar formation

• Longshore drift may cause a spit to grow right across a bay, trapping a freshwater lake (or lagoon) behind it.

• This feature is called a bar.

• An offshore bar forms further out to sea.

• Waves approaching a gently sloping coast deposit sediment due to friction with the seabed.

• The build-up of sediment offshore causes waves to break at some distance from the coast.

hard engineering

Man made structures built to control the flow of the sea and reduce flooding and erosion

Types of hard engineering

• Recurved sea wall

• rock armour

• Gabions

• Groynes

Sea wall

• aim to protect the coast using concrete, steel and/or stone

• Reflect waves back to sea

benefits of a sea wall

• Effective in protecting cliffs from erosion and also act as a barrier to prevent flooding.

• Deflect wave energy back to sea.

• Give people a sense of security.

• Often have a promenade on top, which doubles up as a cycle route.

• Steps at the base of a wall act as seating areas for beach users.

• If well maintained, sea walls can last for many years.

• Sea walls do not impede the movement of sediment down-drift, so they do not disadvantage other areas.

costs of a sea wall

• Sea walls are very expensive to construct and maintain (over £5000 per metre).

• Reflected waves scour the beach and can cause foundations to be undermined.

• Recurved sea walls can increase the erosion of beach material and may destroy habitats.

Rock armour

• consists of massive blocks of natural rock piled up at the base of a cliff.

• The rocks are dumped on top of each other leaving gaps between them that allow water through.

Benefits of rock armour

• Disperses the energy of the waves and reduces their erosional power.

• Structure is quick to build and easy to maintain.

• Much cheaper than a sea wall.

• If well maintained, rock armour lasts a long time.

• It is versatile, as it can be placed in front of a sea wall to lengthen its lifespan or used to stabilise slopes on sand dunes.

• Often used for fishing.

Costs of rock armour

• Access to the beach is difficult as people have to climb over the rock armour.

• Costs may be high especially when the rock is imported.

• Rock armour looks unattractive.

Groynes

• look like wooden ‘fences’ that are built down the beach at right

angles to the coastline