Littoral Zone
The coast as a system
● As with any geographical system, the coast, as a system, has inputs, stores,
transfers and outputs
● The system constantly strives to be in a state of dynamic equilibrium
● The coast can be viewed as both an open system and a closed system
○ It is an open system because it receives inputs from the lithosphere,
atmosphere, hydrosphere, biosphere and cryosphere
○ However, during research and coastline management the coast can be
seen as a closed system where a specific sediment cells examined
The coast as a system
● There are examples of positive feedback at the coast
○ As waves erode the cliff, material is released
○ This material abrades the cliff which results in even more cliff erosion
● There are also examples of negative feedback at the coast
○ As the shore is eroded, material makes the wave cut platform wider
, ○ This can absorb wave energy and reduce the impact at the base of the
cliff
The littoral zone
● The littoral zone is the area of the coast that can be affected by wave action
● It is a dynamic zone which means that it is constantly changing due to the
interaction between processes on land and in the sea
● These changes can be:
○ Long term due to climate or sea level change
○ Short term due to the tides, waves and storms
● It is divided into four zones:
○ Backshore is usually beyond the influence of wave action but can be
affected during storm events
○ Foreshore is the intertidal area between high and low tide
○ Nearshore is the breaker zone where friction between the seabed and
the waves causes them to break
○ Offshore is the area outside t
he influence of waves
The littoral zone
Long Term Processes
● Coastal systems are affected by long term factors which include geology and
changes in sea level
Geology
● The geology is the characteristics of the land which includes both:
○ Rock type
○ Rock structure
● Coasts can be classified as:
○ Rocky
, ○ Sandy
○ Estuarine
● They can also be classified as:
○ Concordant - where different rock types run parallel to the coast
○ Discordant - where different rock types run at right angles to the coast
Sea level change
● Sea level change can occur as a result of:
○ Global warming - natural and enhanced
○ Tectonic activity - which can lead sections of land to rise or subside
● Longer term sea level change can be:
○ Eustatic - when the sea level itself changes
○ Isostatic - when the land rises or falls relative to the sea
● This leads to coasts which are either emergent or submergent
Short Term Processes
● Coasts can also be categorised by short term factors:
○ Waves - can be constructive or destructive
○ Tides - tidal range is the difference between high and low tide
○ Rivers
○ Storm events
● These create coastlines that can be:
○ Retreating or advancing which depends on whether erosion or
deposition dominates
○ Dominated by land based processes (primary coasts) or marine
processes (secondary coasts)
○ Large or small tidal range
○ High or low energy
Characteristics of High and Low Energy Coasts
High Energy Coasts Low Energy Coasts
● Destructive waves ● Constructive waves
● Exposed to strong winds and ● Sheltered locations with short
long fetches fetch
● Higher rates of erosion than ● Higher rates of deposition than
deposition erosion
● Tend to be rocky coasts ● Sandy beaches, salt marshes,
● Steep cliffs - marine cliff profile estuarine and tidal mud flats
● Less steep cliffs - subaerial cliff ● Gentle relief
profile ● Sediment from land and sea
● Headlands, wave cut platforms ● Beaches, spits, coastal plains
Rocky Coasts
, ● Rocky coasts form where there is more resistant geology - in the UK this is
mainly in the north and west of the country
● Cliffs of varying heights and steepness can be found along rocky coastlines:
○ Steep cliffs tend to be found in high energy environments
○ Cliffs with a gentler slope tend to be found in low energy environments
● Erosion is more dominant than deposition
● Two types of erosion may dominate along rocky coastlines:
○ Marine erosion - the action of waves
○ Sub-aerial erosion - weathering and mass movement
Coastal Plain Landscapes
● Coastal plains usually occur where the land gradually slopes down towards
the sea
● Tend to be low relief
● Coastal plains include both:
○ Sandy coastlines
○ Estuarine coastlines
● These are usually low energy coastal environments
● They form due to coastal accretion - when deposition is greater than erosion
● Sediment for deposition comes from:
○ Offshore sources
○ Terrestrial sources
● Dunes form, helping to stabilise the coast and reduce erosion
● Wetlands and marshes form due to poor drainage
● Estuarine coastlines form at the mouths of rivers and are formed from clay
and silt
Discordant & Concordant Coast Formation
Discordant coastlines
● A discordant coastline is one where the rock structures meet the coast at an
angle - run perpendicular to oncoming waves
● Alternating rock types lead to the formation of headlands and bays
● Discordant coasts are also known as Atlantic coasts
Concordant coastlines
● Concordant coastlines are where the rock structures run parallel to the coast
● Dalmatian and Haff coastlines are examples of concordant coastlines
The coast as a system
● As with any geographical system, the coast, as a system, has inputs, stores,
transfers and outputs
● The system constantly strives to be in a state of dynamic equilibrium
● The coast can be viewed as both an open system and a closed system
○ It is an open system because it receives inputs from the lithosphere,
atmosphere, hydrosphere, biosphere and cryosphere
○ However, during research and coastline management the coast can be
seen as a closed system where a specific sediment cells examined
The coast as a system
● There are examples of positive feedback at the coast
○ As waves erode the cliff, material is released
○ This material abrades the cliff which results in even more cliff erosion
● There are also examples of negative feedback at the coast
○ As the shore is eroded, material makes the wave cut platform wider
, ○ This can absorb wave energy and reduce the impact at the base of the
cliff
The littoral zone
● The littoral zone is the area of the coast that can be affected by wave action
● It is a dynamic zone which means that it is constantly changing due to the
interaction between processes on land and in the sea
● These changes can be:
○ Long term due to climate or sea level change
○ Short term due to the tides, waves and storms
● It is divided into four zones:
○ Backshore is usually beyond the influence of wave action but can be
affected during storm events
○ Foreshore is the intertidal area between high and low tide
○ Nearshore is the breaker zone where friction between the seabed and
the waves causes them to break
○ Offshore is the area outside t
he influence of waves
The littoral zone
Long Term Processes
● Coastal systems are affected by long term factors which include geology and
changes in sea level
Geology
● The geology is the characteristics of the land which includes both:
○ Rock type
○ Rock structure
● Coasts can be classified as:
○ Rocky
, ○ Sandy
○ Estuarine
● They can also be classified as:
○ Concordant - where different rock types run parallel to the coast
○ Discordant - where different rock types run at right angles to the coast
Sea level change
● Sea level change can occur as a result of:
○ Global warming - natural and enhanced
○ Tectonic activity - which can lead sections of land to rise or subside
● Longer term sea level change can be:
○ Eustatic - when the sea level itself changes
○ Isostatic - when the land rises or falls relative to the sea
● This leads to coasts which are either emergent or submergent
Short Term Processes
● Coasts can also be categorised by short term factors:
○ Waves - can be constructive or destructive
○ Tides - tidal range is the difference between high and low tide
○ Rivers
○ Storm events
● These create coastlines that can be:
○ Retreating or advancing which depends on whether erosion or
deposition dominates
○ Dominated by land based processes (primary coasts) or marine
processes (secondary coasts)
○ Large or small tidal range
○ High or low energy
Characteristics of High and Low Energy Coasts
High Energy Coasts Low Energy Coasts
● Destructive waves ● Constructive waves
● Exposed to strong winds and ● Sheltered locations with short
long fetches fetch
● Higher rates of erosion than ● Higher rates of deposition than
deposition erosion
● Tend to be rocky coasts ● Sandy beaches, salt marshes,
● Steep cliffs - marine cliff profile estuarine and tidal mud flats
● Less steep cliffs - subaerial cliff ● Gentle relief
profile ● Sediment from land and sea
● Headlands, wave cut platforms ● Beaches, spits, coastal plains
Rocky Coasts
, ● Rocky coasts form where there is more resistant geology - in the UK this is
mainly in the north and west of the country
● Cliffs of varying heights and steepness can be found along rocky coastlines:
○ Steep cliffs tend to be found in high energy environments
○ Cliffs with a gentler slope tend to be found in low energy environments
● Erosion is more dominant than deposition
● Two types of erosion may dominate along rocky coastlines:
○ Marine erosion - the action of waves
○ Sub-aerial erosion - weathering and mass movement
Coastal Plain Landscapes
● Coastal plains usually occur where the land gradually slopes down towards
the sea
● Tend to be low relief
● Coastal plains include both:
○ Sandy coastlines
○ Estuarine coastlines
● These are usually low energy coastal environments
● They form due to coastal accretion - when deposition is greater than erosion
● Sediment for deposition comes from:
○ Offshore sources
○ Terrestrial sources
● Dunes form, helping to stabilise the coast and reduce erosion
● Wetlands and marshes form due to poor drainage
● Estuarine coastlines form at the mouths of rivers and are formed from clay
and silt
Discordant & Concordant Coast Formation
Discordant coastlines
● A discordant coastline is one where the rock structures meet the coast at an
angle - run perpendicular to oncoming waves
● Alternating rock types lead to the formation of headlands and bays
● Discordant coasts are also known as Atlantic coasts
Concordant coastlines
● Concordant coastlines are where the rock structures run parallel to the coast
● Dalmatian and Haff coastlines are examples of concordant coastlines
