3.1 Coastal Processes Flashcards
What is the littoral zone?
The littoral zone is the area of coastline where land is subject to wave action.
What are the 4 zones in the Littoral Zone?
Offshore - area of deeper water beyond where waves break
Nearshore - area of shallow water where waves break
Foreshore - area between high and low tide marks
Backshore - area above high tide mark only affected by waves in high tides
What is the rate of erosion?
Rate of Recession is how fast coastline is retreating and is affected by lithology (rock type)
What are the 3 main types of rock?
- Igneous - very slow erosion rate: crystalline & have few joints eg granite, basalt, dolerite.
- Metamorphic - slow erosion rate: crystalline, foliation and often folded & fractured eg slate, schist, marble
- Sedimentary - fast erosion rate: clastic, geologically young, many bedding planes & fractures eg sandstone, limestone, shale
What are sediment cells?
Coasts that are split into sections and these coasts can be considered an OPEN SYSTEM
What is dynamic equilibrium?
What are inputs and outputs?
Where inputs and outputs are balanced.
- Input: action of waves, wind & currents
- Output: erosion
How many sediment cells are in England & Wales?
There are 11 sediment cells.
What are Sources in a sediment cell?
Where sediment comes from (eg cliffs, offshore bars)
What are transport in a Sediment cell?
Movement of sediment along the shore (eg longshore drift)
What are Sinks in a sediment cell?
Areas of deposition (eg spits, beaches)
What is a feedback loop?
The coastal system maintains dynamic equilibrium through FEEDBACK LOOPS
What is a Negative Feedback Loop?
Lessens any changes that occured within the system.
What is a Positive Feedback Loop?
Enhances any changes that have occurred within the system.
What is a rocky coastline?
High relief, form in areas of high energy, resistant rock, destructive waves.
What is a sandy coastline?
Low relief, form in areas of low energy, less resistant rock, constructive waves.
What is an estuarine coastline?
Low relief, form in river mouths, low energy areas, less resistant rock.
What are the 2 main coastal processes?
- Primary coasts: land based processes.
- Secondary coasts: marine processes
What 2 types of coasts that are linked to sea level change?
- Emergent coasts - rising relative to sea level.
- Submergent coasts - sinking relative to sea.
What are the 2 types of coasts that are linked to wave energy?
- Low energy coasts: sheltered, small fetch, low wind speed, constructive waves.
- High energy coasts: exposed, long fetch, high wind speed, destructive waves.
What are faults?
Major weakness within strata, rocks are heavily fractured.
What are joints?
Occur in most rocks in regular patterns.
What is Valetin’s Classification of Coasts?
Recognizes that coasts can be erosional/depositional and emerging and submerging and that these effects can magnify or neutralize each other. Revised in 1952.
What is the Geological Structure of rock and what are the 3 elements?
Refers to the arrangement of rocks.
- Strata
- Deformation
- Faulting
What is the strata?
Different rock layers.
What is a deformation?
How much rocks are tilted/folded by tectonic activity.
What is faulting?
Major fractures that have moved rocks from their original position.
What is a concordant coastline?
Pacific coasts, rock strata parallel to coastline eg Lulworth (Dorset)
What is a discordant coastline?
Atlantic coasts, rock strata perpendicular at an angle of the coastline eg West Cork Coast (Ireland)
What are cliff profiles?
Influenced mainly by the rocks resistance of erosion and its dip (angle of strata from the horizontal)
What is a horizontal dip?
Vertical profile, notches where soft strata is eroded.
What is a seaward dip? (High angle)
Sloping, low angle profile, vulnerable to rock slides.
What is a seaward dip (low angle)
90 degree + profile, overhanging areas, very vulnerable to rock falls.
What is a landward dip?
Steep profile, very stable cliff, reduced fock falls.
What is coastal vegetation?
Vegetation supports sandy coastlines + protects against recession, as sand dunes are constantly supplied by sediment.
What plants colonize embryo and fore dunes?
Halophytic plants such as sea rockets.
What plants colonize yellow dunes?
Xerophytic and halophytic plants such as marram grass.
What plants colonize grey dunes?
Heathers or lot of humus.
