Geography Paper 1 Coasts

energy and matter can be transferred between neighbouring systems as inputs and outputs

there are no inputs and outputs and matter and energy cant be transferred between systems

Kinetic energy from wind/waves

Thermal energy from the sun

Potential energy from position of matter on slopes

Material from mass movement weathering and deposition

marine/wind erosion from beaches/rock

evaporation

Stores like beaches and nearshore sediment

Flows such as longshore drift

When a system self regulates to restore equal inputs and outputs using negative feedback

A stretch of coastline that has movement of sediment, sand and shingle within it

• 11 large cells in England/Wales

• Boundaries are determined by topography and coastline shape

• Closed systems

• Wind and currents transfer materials between cells

From place to place

Over Time

Generated by frictional drag of wind across ocean

• Longer fetch

• Larger Waves

• More wave energy

• Aeolian processes

• erosion, transportation, deposition

• potential energy due to position above the trough

• Kinetic energy due to motion of water within the wave

• Causes circular motion of water molecules

Distance between two troughs

Distance between trough and crest

number of waves per minute

Time between two consecutive crests

• Smooth ocean wave

• Long wavelength

• Generated by high ocean winds

• Shorter Wavelength

• Spilling

• Plunging

• Surging

• Steep waves

• Break on gentle sloping beaches

• Water spills gently forward

• Moderately steep waves

• Break onto steep beaches

• Water plunges down

• low angle waves

• Break on steep beaches

• Wave slides forward

• Water molecules come into contact with sea floor

• Friction slows and changes wave shape

• Wave bunches up and bottom of the wave slows more than the top

• Crest goes in front of trough and wave breaks

Water moves up the beach by energy from broken waves

Water is pulled back down the beach by gravity

• Low height

• Long wavelength

• Low frequency

• Spilling waves

• strong swash/weak backwash

• spilling waves

• Greater wave height

• Shorter wavelength

• Higher frequency

• Weak swash/Strong backwash

• Plunging waves

The periodic rise and fall of the sea surface

• Gravitational pull of the moon and sun

• Moon has a gravitational pull towards water

• High tides follow moons orbit

• Happen twice a month

• When earth moon and sun are all in line

• Highest tides

• Happens twice a month

• When moon and sun are at right angles to each other

• Lowest tides

Physical and chemical composition of rocks

• Clay has weak due to weak bonds between particles in rock

• Basalt has strong lithology due to dense interlocking crystals

• Rows of rock parallel to the coastline

• Produces Straight coastlines

• Rows of rock perpendicular to the coastline

• Form headlands and bays due to different rates of erosion

• Transport sediment

• Caused by right angled waves breaking

• Creates cusps which cause the rip to have a narrow neck

• Generated by convection and earths rotation

• Have motion due to movement of winds

Transfer heat energy from low latitudes towards the poles

Move cold water towards the equator

• Rivers

• They directly deposit sediment at coasts with a steep gradient

• Mostly happens during floods

• Sediment comes from erosion, weathering and mass movement

• Constructive waves bring sediment from offshore to shore by marine deposition

• Tides and currents also do this

• Wind also blows sediment from bars

• Generally in the form of sand as large particles are too heavy for wind

• Beach nourishment when sediment budget is in deficit

• Sediment is brought by a lorry and dumped on the beach

• Or sand and water can be pumped by a pipeline

• Uses energy to produce physical or chemically altered materials from rock

• Breaks down rock and exposes surface area

• No chemical alterations

When water enters cracks in rock and expands by 10% when it freezes causing rock to break

When heated rock expand and contract when cooled and rock cracks and flakes off

• Decays rock by chemical reactions

• Increase in temp increases chemical reactions

• Sea water is neutral but becoming more acidic due to climate change

When rocks react with oxygen and become soluble in acidic conditions

• When CO2 combines with rainwater to produce carbonic acid

• Carbonic acid then reacts with calcium carbonate to become soluble

• Biological plants and organisms affect the structure and stability of rock

Grow into cracks and joints and exert pressure causing a release and rock breaks off

Organic acids produced in decomposition of plants and animals break down sections of rocks and they become soluble

When forces acting on slope material(gravity) exceed the forces keeping the material of the slope(friction)

• On cliffs more than 40 degree angle

• Rocks become detached by physical weathering

• May be linear

• A fault or bedding plane between layers of rock causes it to slide

• Rotational slides are slumps

• Happen because of undercutting and erosion

• Common in weak rock

• Abrasion

• Attrition

• Hydraulic action

• Pounding

• Solution

Waves with rocks in them scour the coastline and rub against other rock

Rocks collide and wear away to become smoother and more well rounded and eventually become sand

Waves break against cliffs and air/water trapped in cracks becomes compressed and releases pressure

Mass of a breaking wave exerts pressure on rocks causing them to weaken

• Dissolving materials in rock

• Has a small impact as water pH is 7/8

• Solution

• Suspension

• Saltation

• Traction

• Longshore Drift

Minerals dissolve in water until they evaporate

Small particles of sand and silt are carried by currents

Material moves irregularly and bounces along the surface

Largest particles are pushed along the sea floor by water flow

• Waves approach the coastline at an angle due to wind and move up the beach with swash

• Move with backwash perpendicular to the beach and carry sediment within the wave

When there is a loss of energy caused by a decrease in velocity or volume of water

• Rate of sediment accumulation exceeds removal rate

• Waves slow immediately after breaking

• Low energy environments

• During backwash when water percolates into the beach

• During swash when water is not moving

• River mouths and river processes

• Erosion is the main source of rivers load

• Transportation

• Deposition when rivers enter the sea due to reduced velocity

• Tides/currents move in opposite directions to river flow so energy reduced

• Processes carried out by wind

• Erosion when wind picks up sand and moves it by deflation and surface creep

• Transportation by wind instead of water apart from solution

• Deposition when wind speed falls and material is deposited

• Destructive waves break repeatedly on steep slopes

• Undercutting causes a wave cut notch

• Continued undercutting weakens above rock and breaks off causing a cliff

• Undercutting leads to rockfall

• Cliffs retreat parallel to coast

• Undercutting removes basal support

• Rock layers loosened by weathering and they slide into the sea

• Rocks loosened by weathering and wave action

• Strong rock is hard to dislodge

• Gradually lowered slope profile due to weathering and mass movement

• When a discordant coastline has bands of rock perpendicular to coastline

• Stronger rock less easily eroded so form headlands

• Weaker rock is easily eroded so forms bays

• Waves approach an irregularly shaped coastline often a bay/headland

• Slowed by friction in shallower water of the headland

• Refract around the headland

• Energy dissipates in the bays and this leads to deposition

• Narrow steep sided inlets

• Weak points are eroded by wave action

• Initially form as tunnels/caves

• When the roof collapses this is a geo

• If part of the roof of a tunnel or cave collapses along a major joint a vertical shaft is formed

• This reaches the cliff top

• Large waves force water to spray out

1. Wave refraction focuses energy on the sides of headlands

2. Faults and joints are exploited by erosion and a small cave can form

3. Cave extends to the other side of the headland causing an arch

4. Erosion widens arch and weakens supports by weathering and arch collapses

5. This leaves a stack

6. Further erosion causes the formation of a small stump

• Accumulation of material deposited between low tides and highest storm

• Material comes from cliff erosion, offshore and rivers

• Produce a 5 degree beach angle

• compact particles when wet and little friction so material can be carried back down the beach

• Produces steeper beaches

• This is because swash is stronger than backwash

• Formed by pebbles being hurled by storm waves

• Small semi circular depressions that form by collection of waves reaching the same point

• Flatter beaches

• Shallower water

• More friction

• Less wave energy

• Steeper beaches

• Deeper water

• Less friction

• More wave energy

• Long narrow beaches of sand/shingle attached to land at one end

• Extend across bays and estuary’s

• Formed by longshore drift carrying sediment to the end of the beach and into open water

• When a spit continues to grow across until it joins the other side

• Form lagoons of brackish water

• Beaches that connect the mainland to an offshore island

• Formed from spits that grow seaward until they join an island

• Low energy environments

• Vegetated areas of deposited silt and clay

• Salt tolerant plants e.g. eel grass trap sediment and increase height

• Roots stabilise sediment

• High salinity

• Turbid water

• Long periods submerged

• Poor species diversity

• Lower salinity

• Lower turbidity

• Shorter period of submergence

• Higher species diversity

Small depressions that trap water

• Large areas of sediment formed at the river mouth due to deposition and tidal currents

• Rivers entering the sea carrying large sediment

• Low energy environments

• Low tidal ranges

• Upper delta plain is the furthest inland and composed of river deposits

• Lower delta plain is in the inter tidal zone and regularly submerged and has both marine and river sediment

• Submerged delta plain is below mean water level and has marine sediments

• Cuspate shaped by gentle currents

• Arcuate which has a lot of sediment but not enough wave energy to smooth the edge

• Birds foot which has branching patterns when river sediment exceeds wave removal