• input- material/energy that enters system from elsewhere- e.g. a cliff landslide drops sediment onto the beach
  • flow- movement of material/energy within a system- e.g. sand moves along the coast via longshore drift
  • store- a place where material/energy remains temporarily- e.g. sand dunes lieing behind a beach
  • output- material/energy that leaves the system going elsewhere- e.g. storm waves scour sand off beach out to sea 
  • feedback- a system output becomes an input within the same system
  • coast is an open system- material can exit and enter
  • equilibrium- inputs & outputs are balanced e.g.beach not changing size, could be due to feedbacks
  • positive feedback- increases change in system
  • negative feedback- keeps the system balanced
1 of 23

Sediment Cells

  • England and Wales are split into 11 Sediment Cells
  • they are closed systems, sediment doesn't pass from one to another due to topography 
  • each sediment cell contains a sub-sediment, these are open systems
  • there are 3 cells on the east coat, 3 cells on the southcoast and 5 cells on the west coast
  • 4 cells are roughly less than or equal to 200km 
  • 3 longest cells are St Abbs Head to Flamborough Head, river thames to Selsey Bills and Portland bill to Lands end
  • variations in wind direction and tidal currents mean no sediment wil ever be a completely closed system
2 of 23

Physical Factors: wind, waves and tide

  • wind- caused by a difference in energy input from the sun at the poles compared to the equator, causes hot air to move from the equator to the poles and vice versa to balance out temperature difference, the movement of the air via circulation cells causes wind.
  • Waves with SW wind, fetch 8000km, waves with SE wind, fetch 200km
  • waves- wind waves are when wind speed is greater than the spped of a cappilary wave. storm waves are found near a weather event that has caused them, swell waves are ones that have moved far from origin
  • Tides- gravitational forces from the moon and sun cause tides, a tide is where the water is pulled towards the sun and moon
  • the moon pulls water towards it, causing high tide, mirror buldge other side 
  • spring tides (highest) occur when earth, moon and sun line up 
  • neap tides (lowest) occur when they are all at right angles
  • largest tidal range is 17m in Bay of Fundy, Eastern California
  • smallest is less than 1m in eastern mediterranean 
  • small tidal range- erosion concentrated on smaller area
3 of 23

Physical Factors: Geology

  • Lithology- rock type and its physical properties- e.g. how resistant it is
  • erosion- resistant rocks resist erosion e.g. igneous rocks like Granite. Sedimentary rocks aren't resistant and are easily eroded
  • weathering- rocks that contain calcium carbonate like chalk and limestone, are susceptible to weathering - known as carbonation- weak carbonic acid in the sea dissolves calcium carbonate in the rocks
  • Geology- rock jointing, bedding and faulting, permeability
  • jointing- cracks that run vertically
  • bedding planes- horizontally
  • faults- cracks due to tectonic movement that shift big rocks, all cracks speed up denudation
  • Permeability- some rocks have small interconnected holes called pores e.g. chalk, known as primary permeability. other rocks have natural joints and bedding planes that allow water in e.g. limestone, known as secondary permeability
  • permeable rocks erode faster than non-permeable rocks
4 of 23

Physical Factors: Geology 2 and currents

  • strata- layers of rock that build up the crust of the earth. through tectonic movement, rock strata can be thrust parallel to the coast- concordant coastline, or adjacent to it- discordant coastline
  • discordant coastlines have headlands and bays, resistant rock stick out and weaker gets eroded
  • concordant coastlines have coves, if resistant rock gets eroded at a weakness, sea can access the weak rock behind it
  • dip refers to the angle of bedding places relative to horizontal. if cliffs dip towards the sea, they will be eroded faster than dipping towards land
  • Currents- fast moving streams of water within oceans and seas
  • can be local and nearshore e.g. rip currents, or global and offshore e.g. global ocean conveyor system
  • rip currents- flow from coast back out to sea, can be 2.5m/s, when a sand bar or reed lies offshore parallel to the coast with a gap in it, when water returns from swash it will flow to gap
  • rip currents can cause cusps, arc pattern in the sand on ebach because returning water dragged sediment
5 of 23

Physical Factors: Currents 2

  • global currents- caused by equator gaining more solar energy than poles, temperature difference causes warm water to flow from equator to poles along surface and cold water from the poles to the equator along the bed
  • example of warm water ocean current is Gulf Stream from Caribbean Sea to Norwegian Sea, currents affect climate which affects denudation rates along the way
  • warm currents speed weathering up, cold currents slow it down
6 of 23

Coastal Sediment Sources

  • terrestrial sources:
  • - fluvial deposition- sediment is transported down a river and depositied at the coast
  • - cliff weathering and mass movement- sub-aerial processes break up rock and move them
  • - marine eorsion- sediment from on/near shore is moved out to sea by backwash
  • - LSD- sediment is moved along the coast by waves hitting the coast obliquely 
  • - Aeolian dposition- wind picks up small sand particles which are blown inland and dropped
  • Marine sources:
  • - marine deposition- sediment from offshore is moved onshore via constructive wave action
  • Human Sources:
  • beach norishment- humans add sediment to a beach either from inland or offshore deposits
7 of 23

reasons for coastal landforms developing: Geomorph

Weathering- break up of rocks into smaller fragments that remain in situ, and dissolved compounds by physical, chemical and biological processes

  • physical/mechanical- freeze thaw, pressure release, thermal expansion, salt crystallisation, occurs most in areas with large diurnal temperature ranges, less likely to be coastal
  • chemical- oxidation, carbonation, solution, hydrolysis, hydration, the warmer it is, the faster the chemical reactions so larger effect of chemical weathering
  • biological- tree roots and burrowing animals, organic acids
  • Mass movements- after weathering, the particles only stay in situ if friction is stronger than gravity, if not then mass movement takes place, happens if friction is reduced or affect of gravity is increased
  • rock fall- where slopes are steep, regolith will drop to the base
  • flow- where slopes are less steep but prone to be saturated, material will flow like liquid
  • slide- where rock has defined bedding planes, 
8 of 23

reasons for coastal landforms developing: Geomorph

wave erosion

  • abrasion/corrasion- rocks rub against cliff/shore
  • attrition- rock particles collide, breaking up
  • sollution/corrosion- water dissolves rock particles through chemical reactions
  • hydraulic action- water and air is pushed into cracks and compressed, weakening it
  • pounding- mass of water smashing into a rock from a breaking wave

Wave Deposition

  • when kinetic energy falls, the sediment will be deposited, larger particles will be deoposited first as the larger the mass, the more energy required to transport it

wave transportation- waves erode transport material

  • traction- large particles are dragged along the bed. Suspension- very small particles are carried in water as mass is low. Solution- salts are dissolved in sea water. Saltation- small pebbles and gravel bounce along the base of the wave 
9 of 23

reasons for coastal landforms developing: fluvial

  • weathering, mass movement and erosion all occur throughout the drainage basin of a river
  • when the river discharge is high and the river is in flood, the more material is eroded and transported by the river to the coast, when the river meets the sea, its velocity is reduced, causing deposition
  • the smallest clay particles are so small that electrostatic forces keep them suspended in fresh water. when the fresh water meets the sea and becomes brackish, the dissolved salts disrupt the electrostatic forces, causing the particles to flocculate and be deposited
  • fluvial deposition causes mudflats, deltas and salt marshes
10 of 23

reasons for coastal landforms developing: aeolian

  • deposition occurs when velocity falls due to increased friction as it blows inland, can cause sand dunes
  • suspension- very fine material is picked up and carried high into the air by dust storms, <0.15mm
  • surface creep- course material is rolled along the surface of the ground by wind, this is also known as traction as its similar to the process in water, 0.25-2.00mm
11 of 23

distinctive coastal landforms caused by erosion an

Erosional landforms

  • headlands and bays
  • cliffs and platforms
  • geos and blow holes
  • caves, arches, stacks and stumps

Depositional landforms

  • beaches
  • spits and tombolo's 
  • onshore bars
  • salt marshes and deltas
12 of 23

emergent coastal landforms form as sea levels fall

Falls in sea level

  • eustatic sea level change- the sea level falls as there is less water in the oceans and more ice on land
  • isostatic sea level change- the sea level falls as the land rises up, there is no change in volume of the oceans and seas
  • any sea level change is due to both factors, not just one as they occur at the same time, but at different rates and levels of magnitude
13 of 23

emergent coastal landforms form as sea levels fall

Causes in sea level fall

Climate change- changed due to four atronomical factors (Milankovitch cycle) and one geological factor

  • Orbital eccentricity- earth changes orbit from ciruclar to elliptical over a cycle of 100,000 years, circular orbit means the earth is closer to the sun and warmer, elliptical means the earth is further away from the sun and cooler
  • axial tilt- the earths axis changes by 2.4° every 41,000 years, when the earths tilt is at its maximum, summers and warmer and winters are colder
  • equinox precession- the gravity of other bodies in the solar system causes the earths axial tilt to wobble, making a cirucuar motion over 22,000 years. when the northern hemisphere is pointing towards the sun, the temperature range between summer and winter is greater
  • solar cycle- sun has a cycle of 11 years, over which the amount of radiation increases and then decreases. over a longer priod, the cycle changes with a minimum and maximum number of hot spots. impact is complex
14 of 23

emergent coastal landforms form as sea levels fall

Geological Factor

  • volcanic activity
  • in the short term, volcanoes emit large amounts of ash, the smallest particles stay in the stratosphere for months and reflect incoming solar radiation, causing cooling
  • they also give off sulphur dioxide which reacts with acid to form sulphuric acid droplets in the stratosphere which are highly reflective so again reflect solar radiation
  • when Mount Pinatubo erupted in 1991, emitted so much sulphur dioxide that earths climate cooled by 1.3°C from 1991-1994.
  • a cooling climate reduces sea level change by changing the balance of ice on land vs the water in seas and oceans
  • as temperature falls, more precipitation turns to snow and ice on land and less melts, therefore glaciers and ice caps grow, oceans and seas shrink in volume
15 of 23

emergent coastal landforms form as sea levels fall

raised beaches

  • when sea level falls, it can leave several raised beaches above the current one. raised cliffs and raised wave cut platforms can also be found
  • example of raised beach, paleo-cliff and paleo-wave cut platform- Langerstone Point, Devon

modifications of emergent coastal landforms

  • once coastal landforms have emerged, it will start to be destroyed by denudation
  • biological weathering will increase- animals and plants will colonise on raised beaches and paleo-wave cut platforms as the area will not be as harsh an environment as won't be affected by marine processes
  • chemical weathering will increase- organic matter will cause carbonation and chelation. this might become more significant in warmer climates as water will become more acidic and chemical reactions will occur at a faster rate
  • physical weathering will increase- in colder climates, freeze-thaw will break up the rock and in extreme periglacial conditions could cause cryoturbation (Controtions in the rocks)
16 of 23

emergent coastal landforms form as sea levels rise

Causes of sea level rise

  • temperature rises so less precipitation turns to ice and snow on the land and more ice melts, therefore glaciers and ice caps shrink in size, oceans and seas grow in volume
  • when temperatures are higher, thermal expansion of the seas and oceans occur. it is thought that a 1°C rise in temperature would result in a 2m rise in sea level due to thermal expansion

Flandrian Transgression

  • the last glacial period is known as the Wurm glaciation, the warming that has occured over the last 25,000 years caused a rise in sea level called the Flandrian Transgression, sea level was much lower by about 120m
17 of 23

emergent coastal landforms form as sea levels rise

Rias- river valleys that have been flooded by rise in sea level

  • as they used to be river valleys, they have gentle sloping sides, usually have irregular winding course, near the coast, The Kingsbridge Estuary, Devon

Fjords- glacial U-shaped valleys that have been flooded by rise in sea level

  • in areas where glaciation carved out U-shaped valleys, rising sea level forms Fjords, they are much deeper and narrower than rias and can extend back inland for hundreds of miles
  • often shallowest nearest the sea as glacial erosion was weakest here as ice was thinnest
  • Milford Sound, New Zealand
  • increased global warming and further rise in sea level are likely to increase the water depth in fjords and increase denudation to the valley sides
18 of 23

emergent coastal landforms form as sea levels rise

Shingle Beaches

  • during Wurm glacial period when sea level was lower, fluvial sediment built up in these paleo-coastal areas. joined by glacial sediment when the ice melted that was deposited in large quantities in outwash plains
  • as sea levels rose from 25,000BP the sediment was pushed on-shore
  • During Flandrian Transgression in UK, large quantities of sediment were moved around 50km onshore until sediment hit the land around Abbotsburry and Portland, forming chesil beach
  • likely to be damaged by erosion due to increase in warming of climate. this is because sea level will rise and there will be an increase in storm frequency. both will increase the magnitude of marine erosion
19 of 23

Human Activity intentionally causes change in coas

4 approaches to coastal management in the UK set out in the UK Coastal Management Plans:

  • Hold the line- use strategies that maintain coastline in its current position- Mappleton on the Holderness Coast, UK
  • advance the line- use strategies that reclaim the land extending the coastline out to sea- not currently used in the UK- Netherlands
  • retreat the line- use strategies that allow the sea to reclaim the land, causing the coastline to retreat via managed reallignment- Blackwater Estuary, Essex
  • do nothing- leave the coastline to it's own devices as management is too costly and not beneficial enough- St Aldhems Head, Dorset
20 of 23

Coastal Management Strategies

See table on notes

21 of 23

Human Activity unintentionally causes change in co

Economic development of coastal areas

  • coastal development- Australia Brazil and UAE have seen extensive coastal development of mainly residential and tourist land uses
  • mineral resource exploitation- Netherlands, New Zealand have engaged in large scale offshore dredging for sand and gravel minerals

Urban Development of coastal areas- Persian Gulf, Middle East

  • 40% of the Persian Gu coastline has been subjected to urban, industrial, and more recently, tourist development over the last 20 years. 
  • Dubai has seen a vast amount of coastal development primarily in the construction of its artificial islands along its Gulf Coast
  • Palm Jebel Ali , 13km^2, commercial, residential and leisure
  • The Palm Jumeirah, 6km^2, as above
  • The World, under construction, 55km^2, as above
  • Deira Island, under construction, 46km^2, as above
22 of 23

Human Activity unintentionally causes change in co

Impact of the Palm Islands and World Islands

  • Persian Gulf is a fairly shallow sea that experiences high velocity daytime onshore winds called Shamals. they influence wave energy and affect erosion and and transportation along the coastline. LSD in this part of the UAE coastline is predominantly in a NE direction
  • The Palm Jumeirah required just under 200 million m^3 of sand to build much of which was dredged from the sea bed 7miles off the coast. will have affected offshore sediment processes
  • the breakwaters were formed using sand from borrow pits either side of them, this caused high levels of cloudy water that were long lasting
  • Construction caused the LSD supply of sediment to a beach down the coast to be cut off, this is because wave energy is being affected by the artificial islands. this caused erosion rates to increase to nearly 25m per year. the construction of the world islands caused the direction of LSD to reverse
  • this is all being combatted through large scale beach nourishment schemes along with beach re-profiling and the construction of groynes. in other areas, the islands have sheltered the beaches and erosion rates have dropped
23 of 23


No comments have yet been made

Similar Geography resources:

See all Geography resources »See all Coastal environments resources »