Topic 2 – Coastal landscapes and change
Why are coastal landscapes different, and what processes cause these differences?
Coastal features and landscapes:
The littoral zone
The littoral zone contains many coastal sediments. Waves currents and tides move these
sentiments around in a zone along the coast called the littoral zone.
This zone is subdivided into:
- Backshore
- Foreshore
- Nearshore
- Offshore
Interaction of natural processes within the Littoral zone:
- There are inputs of sediment from the sea and current from rivers flowing of the
land.
- Weathering and mass movement occur in the backshore
- Constructive and destructive waves occur on the foreshore and nearshore, causing
deposition and erosion
- Tidal range affects all parts by determine where wave action takes place
- Offshore currents and longshore drift may move sediments some distance along a
coast
Interference of human activities on these natural processes:
- Dredging of rivers to make them deeper for shipping
- Dredging of offshore areas to get sand and gravel for construction
- Building of coastal defences against erosion and flooding
Rapid change can take place when there is increasing energy in the natural processes or
when the impacts of human activities are not carefully considered.
Classification of coasts:
Sections of coasts can be classified into different types depending on:
- The geology
, - Sea level rise and fall + Land level rise and fall
o Long- term changes
- Erosion + deposition
o Short-term changes
o Advancing or retreating coasts
High energy and low energy coasts:
The amount of energy in the coastal environment will determine the landscapes of the
coast.
- This energy is mostly provided by waves, but also to some extent by the weather and
rivers.
-
, Geological structures at different scales:
The shape of the coast is largely determined by geology and wave action.
Aspects of geology:
- Resistance to erosion + weathering
o Degree of consolidation (how well the rock is stuck together)
- Number of joints or bedding planes
- Amount of folding
Wave characteristics:
- Energy
o Related to size and shape
- Length of fetch
- Prevalent and dominant wave direction
- Depth of nearshore and offshore water
Concordant and discordant coasts:
Concordant (or dalmatian) – These coastlines occur where the folding or arrangement of
rock types on a large scale is parallel to the coast.
- Alternating hard and soft rocks in the rock layers, lie in the same direction as the
coastline.
Discordant (or Atlantic) – These coastlines occur where the folding or arrangement of rock
types on a larger scale is at a right angle to the coast.
- Alternating hard and soft rock bands create headlands where there is more resistant
rock, and bays where there is less resistant rock.
Haff coastlines – form in low energy environments where there is deposition of muds and
sands.
- Large lagoons are found behind the deposits parallel to the shoreline.
Coastal morphology:
Geological structure has a major influence on coastal morphology (shape) and erosion rates.
Types of rock:
Why are coastal landscapes different, and what processes cause these differences?
Coastal features and landscapes:
The littoral zone
The littoral zone contains many coastal sediments. Waves currents and tides move these
sentiments around in a zone along the coast called the littoral zone.
This zone is subdivided into:
- Backshore
- Foreshore
- Nearshore
- Offshore
Interaction of natural processes within the Littoral zone:
- There are inputs of sediment from the sea and current from rivers flowing of the
land.
- Weathering and mass movement occur in the backshore
- Constructive and destructive waves occur on the foreshore and nearshore, causing
deposition and erosion
- Tidal range affects all parts by determine where wave action takes place
- Offshore currents and longshore drift may move sediments some distance along a
coast
Interference of human activities on these natural processes:
- Dredging of rivers to make them deeper for shipping
- Dredging of offshore areas to get sand and gravel for construction
- Building of coastal defences against erosion and flooding
Rapid change can take place when there is increasing energy in the natural processes or
when the impacts of human activities are not carefully considered.
Classification of coasts:
Sections of coasts can be classified into different types depending on:
- The geology
, - Sea level rise and fall + Land level rise and fall
o Long- term changes
- Erosion + deposition
o Short-term changes
o Advancing or retreating coasts
High energy and low energy coasts:
The amount of energy in the coastal environment will determine the landscapes of the
coast.
- This energy is mostly provided by waves, but also to some extent by the weather and
rivers.
-
, Geological structures at different scales:
The shape of the coast is largely determined by geology and wave action.
Aspects of geology:
- Resistance to erosion + weathering
o Degree of consolidation (how well the rock is stuck together)
- Number of joints or bedding planes
- Amount of folding
Wave characteristics:
- Energy
o Related to size and shape
- Length of fetch
- Prevalent and dominant wave direction
- Depth of nearshore and offshore water
Concordant and discordant coasts:
Concordant (or dalmatian) – These coastlines occur where the folding or arrangement of
rock types on a large scale is parallel to the coast.
- Alternating hard and soft rocks in the rock layers, lie in the same direction as the
coastline.
Discordant (or Atlantic) – These coastlines occur where the folding or arrangement of rock
types on a larger scale is at a right angle to the coast.
- Alternating hard and soft rock bands create headlands where there is more resistant
rock, and bays where there is less resistant rock.
Haff coastlines – form in low energy environments where there is deposition of muds and
sands.
- Large lagoons are found behind the deposits parallel to the shoreline.
Coastal morphology:
Geological structure has a major influence on coastal morphology (shape) and erosion rates.
Types of rock:
