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• Coastal processes includes landscapes and features of the littoral zone as well as the Influence of Geological Structure in addition to Factors Affecting Coastal Recession & Stability

Landscapes & Features of The Littoral Zone

• As with any geographical system, the coast has inputs, stores, transfers, and outputs

• The system strives to be in a state of dynamic equilibrium

• The coast is both an open and closed system.

• As an open system it receives inputs from the lithosphere, atmosphere, hydrosphere, biosphere, and cryosphere.

• A closed system is seen when a specific sediment cell is examined during research and coastline management

• There are examples of positive feedback at the coast

• Waves erode the cliff, material is released

• The released material further erodes the cliff, this results in more cliff erosion

• There are examples of negative feedback at the coast

• Material makes the wave-cut platform wider as the shore erodes

• Waves 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.
• The littoral zone is a dynamic zone, it is constantly changing due to the interaction between processes on land and in the sea
• Changes from long-term climate or sea level change and short term tides, waves, and storms
• The littoral zone is divided into four zones
• Backshore: beyond the influence of wave action but can be affected during storm events
• Foreshore: the intertidal area between high and low tide
• Nearshore: the breaker zone where friction between the seabed and the waves causes them to break
• Offshore: the area outside the influence of waves

Long Term Processes

• Coastal systems are affected by geology as well as changes in sea level.
• Geology covers both rock type and rock structure
• Coasts are classified as rocky, sandy, or estuarine
• Coasts can also be classified as concordant or discordant
• Sea level change results from global warming or tectonic activity
• Longer-term sea level change can be eustatic or isostatic leading to emergent or submergent coasts

Short Term Processes

• Coasts are categorized by short-term factors.
• Waves can be constructive or destructive
• Tides have a tidal range which is the difference between high and low tide
• Rivers and storms are also short term factors
• They can be retreating or advancing, depending on whether erosion or deposition dominates

High and Low Energy Coasts

• Domination by land-based processes (primary coasts) or marine processes (secondary coasts) is a factor

• Large or small tidal range is a factor

• High or low-energy

• High Energy Coasts; Destructive waves, Exposed to strong winds and long fetches, Higher rates of erosion than deposition, Tend to be rocky coasts, Steep cliffs - marine cliff profile, Less steep cliffs - subaerial cliff profile, Headlands, wave-cut platforms

• Low Energy Coasts; Constructive waves, Sheltered locations with short fetch, Higher rates of deposition than erosion, Sandy beaches, salt marshes, estuarine and tidal mud flats, Gentle relief, Sediment from land and sea, Beaches, spits, coastal plains

Rocky Coasts

• Rocky coasts have resistant geology, they are mainly located in the north and west of the UK
• Cliffs of varying heights and steepness can be found along rocky coastlines
• Steep cliffs are located in high energy environments
• Cliffs with gentler slopes are located in low energy environments
• Erosion is the dominant process
• Two types of erosion can dominate along rocky coastlines:
• Marine erosion is the action of waves
• Sub-aerial erosion is weathering and mass movement

Coastal Plain Landscapes

• Coastal plains occur where the land gradually slopes down towards the se
• Tend to be low relief
• Coastal plains include sandy and estuarine coastlines
• These are usually low-energy coastal environments
• They form due to coastal accretion where deposition is greater than erosion

Sediment

• Sediment for deposition comes from both offshore and 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 from clay and silt

Discordant & Concordant Coast Formation

• 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 are where the rock structures run parallel to the coast
• Dalmatian and Haff coastlines are examples of concordant coastlines

Influence of Geology on Coastal Morphology

• Coastal morphology is the shape and form of the coastline
• Coastal morphology is influenced by the rock type (geology) and structure

Concordant coastlines

• Lulworth Cove in Dorset is an example of a concordant coastline
• More resistant Portland Limestone runs parallel to the sea with less resistant Purbeck Limestone and Wealden Clay behind it
• The formation of coves has occurred where the water has broken through at weaker points in the Portland Limestone

Dalmatian coastline

• The Dalmatian coast in Croatia is another example of a concordant coastline
• Formed as a result of tectonic forces and sea level rise
• Tectonic activity forms anticlines and synclines which run parallel to the sea
• Sea level rise after the Devensian Glacial then flooded the synclines leaving the anticlines standing above the water
• Consisting of a series of islands which run parallel to the coast

Haff coastline

• Located along the southern Baltic coastline
• During the Devensian Glacial large amounts of sand and gravel were deposited offshore
• After the glacial period had ended the material was then deposited nearer to the land by constructive ways
• Forming bars across bays and river mouths trapping the water behind to form a lagoon (Haff)
• These are a feature of low-energy coastlines

Discordant coastlines

• To the east of Lulworth Cove in Dorset, the coastline runs north to south so the rocks meet the coast at an angle creating a discordant coastline
• Causing form headlands and bays

Wave Refraction

• Wave refraction changes the amount of energy reaching the shore on a small local scale
• Wave energy concentrates at the headland which increasing the rate of erosion

Influence of Geological Structure

• Geological structure is how that rocks are folded or tilted - lithology
• Lithology can refer to:
• Strata being layers of rock
• Bedding planes being horizontal cracks created by pauses in rock formation
• Joints being vertical cracks caused by tectonic movement or contraction
• Folds are the the result of pressure during tectonic movement causing the rock strata to fold
• Faults are the result of stress or pressure causing it to fracture
• Dip is the angle of the rock strata

Cliff profiles

• Cliff profiles are the angle and height of the cliff face
• A profile also includes features such as wave-cut notches
• Different lithology creates different cliff profiles

Factors Affecting Coastal Recession & Stability

• Coastal recession is the retreat of the coastline further inland
• Coastal recession may be as a result of erosion, sea level rise and submergence
• Where coastal recession is the result of erosion it is dependent on the lithology of the coast

Mineral composition

• Some minerals are more reactive than others
• Affecting the rate of chemical weathering for example:
• Calcite is reactive and so easily chemically weathered
• Quartz is not reactive (inert) so chemical weathering is much slower

Rock classification

• Sedimentary rocks forms from lithification which is compaction and cementation of sediment
• Ex: shales, sandstone, and limestone
• Sedimentary rocks:
• Erode and weather rapidly compared to other types of rock
• Form in layers
• Have weak bedding planes
• Clastic meaning made of clasps (sediment particles)
• Heavily jointed
• Often have many bedding planes and fractures

Metamorphic rocks

• Forms when sedimentary and igneous rocks are altered through heat and pressure, but do not melt in the process
• Ex: slate and marble.
• Metamorphic rocks:
• Have a crystalline structure
• Often folded and faulted
• More resistant thaan sedimentary rock but less resistant than igneous rocks
• Crystals have a parallel arrangement (foliation) which means they are weaker than igneous rock

Igneous rocks

• Forms when molten rock from the Earth's mantle cools and hardens
• Ex: granite and basalt
• Igneous rocks:
• Erode and weather slowly
• Can be categorised into two types:
• Intrusive igneous rock forms within the ground, cools slowly, and has large course crystals
• Extrusive igneous rock - forms on the Earth's surface, cools quickly, forming smaller crystals
• Has interlocking crystals
• Fewer joints and weaknesses than in other rocks

Differential Erosion

• The changing rates of erosion of different rock types is known as differential erosion
• More resistant rocks erode more slowly compared to less resistant rocks
• Differential erosion:
• Leads to complex cliff profiles
• Influences rates of recession
• The differences in geology contribute to landforms generated by processes on the coast
• On a discordant coastline differential erosion leads to headlands and bays

Role of Vegetation

• Vegetation helps to stabilise coastlines because plant roots bind the soil/sand together which reduces erosion, vegetation reduces wind speeds which decreases erosion and increases deposition and dead plant material adds organic matter to the sand and eventually leads to the formation of soil
• Vegetation is often sparse in coastal environments because of exposure to salty/saline water, evaporation of water which leads to increased salinity and high wind speeds in addition to lack of shade, nutrients plus water in the free-draining sediment is not retained
• Pioneer species in the coastal environment are the first plans to grow in the environment, which allows less able to survive and thrive due to the modification of conditions
• Pioneering species can help to stabilise the sediment, add organic matter, increase shade and trap more sediment
• Sand dune and salt marsh succession is an example of this process
• Sand dune which is the succession in a sand environment is known as a psammosere is an example of a dynamic environment

Sandy Beaches

• Sandy beaches usually have sand dunes at the rear because of strong onshore winds transporting dried, exposed sand
• Obstacle (rubbish, rocks, driftwood etc.) can begin to trap send trap and deposit sand grain
• Sand grain trap turns into the sand embryo dunes
• Over time, the ridges of the dunes will turn into being colonized and fixed by vegetation through succession
• The wind transport ridges inland due to onshore winds pushing the seaward side to the leeward side
• Interaction of winds and vegetation make up the formation of sand dunes
• The first plants (pioneer species) deal with:
• Salinity
• Lack of moisture due to highly permeable sand drains
• Wind
• Temporary submergence through wind-blow

Embryo dunes

• Wind-blown dried sand is trapped by debris and deposition
• Pioneer species such as lyme grass and sea couch grass begin to colonise is halophytic plants
• Very fragile and reach a maximum height of 1 metre
• Little soil content and high pH levels (alkaline)

Fore dunes

• The embryo dunes bring some protection against the prevailing wind
• Marram grass plants grow from the protection of winds stabilising with their root system to 3m to reach the water table
• Plants add organic matter making its dunes suitable for growth for other later growing plants
• Allowing other species of plant to grow: marram grass
• A microclimate will form to facilitate stabilization
• Reaching a maximum height is 5m
• These are initially yellow but organic soil adds dark humus
• Microclimate forms in the dune slack Marram grass till dominates more vegetation. Insects and delicate insects are found throughout the dune slacks
• 20% and 80% of the dune is exposed
• Not exceed above 8 metre

Grey dunes

• Grey dunes have more stabilize with than 10, the sand are exposed and a large amount of the biodiversity is measured throughout.
• Soil acidity and water is a increase throughout is added
• Shrubs and bushes create a spear for these to occur The peak measure 8-10m above the rest.

Mature dunes

• In the most stabilizes position, hundreds of shoreline can be found at most positions

Salt marsh succession

• Succession in saltwater is a halosere
• Plants are adapted to conditions that Halophytic plants are able to withstand
• Salt marshes develop in estuarine areas because: Rivers provide a steady sediment supply, Provides the right environment fresh and saltwater mix, Shelter from strong waves
• A steady supply of sediments, the liver provides steady supply, provides the right environment of freshwater saltwater mix and shelter from strong waves
• This causes flocculation where clay particles stick together and clay particles sing causing to build up
• The sediment is colonized by algae, it forms a bond with the sediment together and increases organisms trapping other sediments to bind The sediment starts the build up and the ride is covered less and less
• And other plants such as cordgrass the colonized allowing the sediment to increase, creating the tide, to cover the highest of highs
• A couple of sea creatures that can find it such as sea lavender sea thrift
• All saltiness the sea creatures the other parts of the colonized is to achieve equilibrium.