Coastal systems and landscapes (booklet 2)

Question 1

What are different inputs in systems?

Answer 1

The geology and lithology of the coast
The angle or dip of the coastline in front of the headland
The nature of the waves approaching the coast
The direction and strength of the prevailing wind

Question 2

What are the different processes in a system?

Answer 2

The different rates of erosion of different rocks
Wave refraction
Erosion of the headland
Deposition in the bay

Question 3

What are the different outputs in systems?

Answer 3

The characteristic features of the resulting landscapes including:
the headland and bay
the erosional features of the headland
the depositional features in the bay

Question 4

What are concordant coastlines?

Answer 4

Where the rock band runs parallel to the coastline

Question 5

What are discordant coastlines?

Answer 5

Where the rock band runs at right angles to the coastline.

Question 6

How are wave cut platforms formed?

Answer 6

Waves focus erosion between the high and low tide level (through abrasion and hydraulic action)
This leads to a wave cut notch developing at the foot of a cliff
As the wave-cut notch grows the cliff is undercut, until eventually the unsupported rock collapses.
The debris now protects the foot of the cliff from further erosion, until it is broken down (by abrasion and attition) and carried away.
As the cliff retreats inland the gently sloping platform of rock is left behind.

Question 7

Explain the formation of a cave.

Answer 7

Cracks at the base of the headland within the inter tidal zone become exposed through hydraulic action, which pressurises air, forcing the crack to widen. Cracks are further widened by weathering processes such as salt crystaliisation and wet and dry weathering that affects chalk. Over time the cracks widen and develop as wave-cut notches. Further processes of abrasion and hydraulic action will deepen the notch to form caves.

Question 8

Explain the formation of an arch.

Answer 8

After a cave has formed:
As a result of wave refraction, which distorts the wave direction, destructive waves concentrate their energy on the sides. This deepens the cave.
Wave refraction effects all three sides of the headland. If two caves are aligned the waves may cut through to form an arch. Wave-cut notches widen the base of the arch.

Question 9

Explain the formation of a stack.

Answer 9

After the formation of a cave and an arch:

Over time the arch becomes unstable and collapses under its own weight to form a pillar of rock, called a stack.

Question 10

Explain the formation of a stump.

Answer 10

After a cave, arch and stack:
The stack is further eroded at the base creating new wave-cut notches. Sub-aerial processes continue to weaken the stack from above.
Eventually the exposed stack will collapse to form a stump. The broken material is further eroded through attrition and transported away to be deposited within the bay.

Question 11

What is a geo?

Answer 11

Along a joint the sea will cut inland, widening the crack to form a narrow steep sided inlet known as a geo.
It is formed by the action of the waves eroding the lower portion of a cliff. A depression or sea cave may form. The cliff face above the cave can erode and collapse over a period of time, creating a geo or extending the geo deeper into the cliff.

Question 12

What is a blowhole?

Answer 12

Formed as a sea cave grows landwards and upwards into vertical shifts and expose themselves towards the surface, which can result in hydraulic compression of sea water that is released through a port from the top of the blowhole.

Question 13

What are drift aligned beaches?

Answer 13

Beaches are produced where waves break at an angle to the coast. The swash therefore occurs at an angle but the backwash runs perpendicular to the beach. As a result, material is transported along the beach via longshore drift.

Question 14

What are swash aligned beaches?

Answer 14

becahes are produced where the waves break in line (parallel) with the coast. Swash and backwash movements move material up and down the beach producing aforementined beach profile features. Swash aligned beaches are smoothly curved, concave beaches. The beach face is orientated parallel to the fronts of the demonant waves. Beaches which face the waves are termed swash aligned.

Question 15

What is a cusp?

Answer 15

Along a relatively straight beach face, water is attracted into small depressions and accelerates. Sediment is eroded to make the depression deeper and so it attracts more water and further accelerates flow (Positive feedback).
Small ridges on the beach repel water and cause flow to decelerate. At these locations, lower energy results in deposition, which increases the size of the ridge. As the ridges bceome larger, negative feedback starts to operate as swash runs out of energy before reaching the back of the cusp, and so no sediment is removed.

Question 16

What is a berm?

Answer 16

Beach ridges are built up by constructive waves and berms mark the successive lower high tides (below a storm beach) as the cycle goes from spring to neap.

Question 17

What is a storm beach?

Answer 17

Strong swash at spring high tide will create a storm beach at the back of the beach. This is a ridge composed of of the biggest boulders thrown by the largest waves, above the usual high tide mark.

Question 18

What are ridges, runnels and pools?

Answer 18

Most barrier islands have a series of dune ridges on their seaward face.

Question 19

What are off-shore bars?

Answer 19

Breakpoint bars form as material moves onshore where waves interact with the seabed at depths less than wave base. In addition, material moves offshore.
A bar forms when sediment flows converge.

Onshore movement generally occurs when wave energy is low to moderate.
Offshore migration is more often associated with higher energy waves when backwash flows are able to carry sediment along the bed.

Question 20

What are barrier beaches?

Answer 20

If a spit develops across a bay where there is no strong flow of water from the landward side, it is possible for the sediment to reach the other side (known as a bar).
Colonisation of plants on the barrier can make it more stable and permenant.

Question 21

What is a barrier island?

Answer 21

An elongated bank of deposited sand or shingle lying parallel to the coastline and not submerged by incoming tides. Where the bank is high enough to allow sand dunes to develop is known as a barrier island. Often the sheltered area between the barrier beach and land becomes a lagoon or coastal marsh.

Question 22

How can barrier islands be formed?

Answer 22

Can form from spits e.g. when a storm digs an inlet through the spit a barrier island is formed.

Question 23

What is a tombolo?

Answer 23

Formed when a spit connects the minland coast to an island.
May also form due to wave refraction. Waves refraction can cause deposition to occur behind an island.

For example, Chesil Beach and The Angel Road of Shodo Island, Japan.

Question 24

What is a pioneer species?

Answer 24

The first plants that colonise an area, usually with special adaptions.

Question 25

What is psammosere?

Answer 25

Vegetation succession that originated in a coastal sand dune area.

Question 26

What is saltation?

Answer 26

Rocks and sand that is moved in a series of leaps across a river or sea bed or the desert floor.

Question 27

What are embryo dunes and foredunes?

Answer 27

20-150m inland 
0-100 years old 
Poor water retention 
Strong onshore winds 
Sand builds up against pioneer plants  e.g. sea rocket

Question 28

What plants are found in embryo dunes?

Answer 28

Sea rocket, saltwort, sandwort and sea couch.

Waxy leaves to retain moisture
Deep roots to tap into moisture

Question 29

What are yellow dunes?

Answer 29

150-300m inland
100-125 years old
Reduced windspeeds
More humus forming         
Yellow soil
More semi-fixed = more stabalised
Less hardy plants can grow.

Question 30

What plants grow in yellow dunes?

Answer 30

Marram grass

• salt tolerant
• inrolled leaves
• long tap roots
• less alkaline soil

Question 31

What are grey (fixed) dunes?

Answer 31

300-500m inland 
125-150 years old 
More sheltered 
Little mobile sand 
Improved nutrient supply and water retention 
Surface lichens give grey appearence

Question 32

What are grey (fixed) dunes?

Answer 32

300-500m inland 
125-150 years old 
More sheltered 
Little mobile sand 
Improved nutrient supply and water retention 
Surface lichens give grey appearence

Question 33

What are dune slacks?

Answer 33

500-700m inland
Moisture loving plants
Low lying hollow between ridges

You find rushes and reeds here.

Question 34

What is dune heath/woodland?

Answer 34

200m-2.5km inland 
200-more than 400 years olds 
Maritime influence is minimal 
Nutrient rich soil
Climax vegetation. 

You find heather and sea buckthorn.

Question 35

Describe the formation of sand dunes.

Answer 35

There is bare sand
Salty, alkaline conditions - little organic matter
Embryo dunes form
Pioneer species invade, colonise and trap sand moving by creep and saltation.
Pioneer plants die
More plant species (other than pioneer plants) can grow.
Soil conditions improve
Organic matter is added to sand and water retention improves
Higher species biodiversity
Moisture loving plants develop in dune slacks.
Trees/scrub can now be supported
Climax vegetation.

Question 36

What is an estuary?

Answer 36

The tidal mouth of a large river where the flow is influenced by both the downstream flow of the river and the inward and outward movement of the tide.
E.g. The Severn Estuary.

Question 37

What are mudflats?

Answer 37

Area of sheltered coastline which don’t experience powerful waves. Often located in estuaries or on the landward side of a spit. They are submerged at high tide and exposed at low tide.

Question 38

How do mudflats form?

Answer 38

Rising tides create a buffer to the river flow slowing velocity and leading to considerable deposition. Most of the sediment that accumulates here is mud.

Question 39

What is flocculation?

Answer 39

As 2 flows meet the fine particles settle out of suspension by the process of flocculation.

Question 40

What is halosere?

Answer 40

Over time mudflats can develop into salt marshes, which exhibit a clear vegetation succession - called a halosere.

Question 41

What are the four elements necessary for the intial development and growth of a saltmarsh?

Answer 41

A relatively stable area of sediment covered by the tide for a short time.
A supply of suitable sediment available.
Low water velocities for some of the sediment to be deposited.
A supply of seeds to establish vegetation cover.

Question 42

Explain the formation of a saltmarsh?

Answer 42

Expansive mudflats can form that develop into saltmarshes.

Thin ;ayers of mud are exposed at low tide. (eelgrass is the pioneer plant).
The mud deepens; pioneer plants establish trapping more mud. Channels are cut by receeding water. (glasswort, cordgrass and spartina are the plants found here)
More plants higher up the marsh trap more sediment causing the surface level to rise and the channels to deepen ( meadow grass and sea lavender)
Now the marsh is only covered at high tide .
Mud deepens, marsh grows and more plants colonise until largely covered by vegetation. Only the highest spring tides will cover this area. Salt pans may form. (moisture tolerant plants such as Ash).

Question 43

What is a halophyte?

Answer 43

Halophytes are salt tolerant species such as glasswort and cordgrass.

Question 44

What is a salt pan?

Answer 44

Salt water is trapped in hollows.
It evaporates.
Leaves a very salty environment.

Question 45

What are the inputs, processes and outputs involved in salt marsh development?

Answer 45

Input - sediment from river and the sea
- flow of the river/currents/tides

Processes - flocculation
- plant colonisation

Outputs - mud flat initially and salt marsh after colonisation.

Question 46

What is eustatic change?

Answer 46

Global change in sea level (rise or fall)

Question 47

What are the causes of eustatic sea level rise?

Answer 47

Climate warming (melting of glaciers/ice sheets)

Thermal expansion of water

Question 48

What are the causes of eustatic sea level fall?

Answer 48

Climate cooling (glaciation, slowed hydrological cycle).

Thermal contraction of water.

Question 49

What is isostatic change?

Answer 49

Local change in level of land relative to the sea.

Question 50

What are submergent features?

Answer 50

Features that have been formed by the sea level rising or the land level falling (drowned features).

Rias, Fjords, Dalmatian Coasts

Question 51

What are emergent features?

Answer 51

Features above the current level of high tide due to a fall in sea level or a rise in the level of the land.

Raised beaches, marine platforms.

Question 52

What are dalmatian coasts? (submergent)

Answer 52

Mountains run parallel or concordant to the coastline.

Coastal submergence produces long, narrow inlets with a chain of islands parallel to the coast.

Sea level has risen and flooded valleys in a mountain range. The tops of the ridges remained exposed, forming a series of off-shore islands running parallel to the coast.

Typically called Dalmatian coasts or Pacific coasts as this type of coastline is typical of both areas.

Question 53

What are Rias?

Answer 53

A river valley that has been flooded. They have a dendritic drainage pattern.

The deepest part is at the mouth.

Question 54

What are fjords?

Answer 54

U-shaped valleys that have steep valley sides. They generally consist of a rock basin with a shallower section at the end, known as the threshold. The threshold is thought to be due to reduced glacial erosion as the glacier came into contact with the sea. (Glaciers bulldoze sediment down time the coast, creating a threshold, a ridge of sediment).

Deepest in the middle.

Question 55

What is a raised beach?

Answer 55

Sediment that was deposited when the sea level was higher = depositional feature.
FOR EXAMPLE, the North Coast of Spain.

Question 56

What is a marine platform?

Answer 56

An erosion all feature. It is rock that was cut when sea level was higher e.g. an old wave cut platform.

Question 57

How is sea-level rise impacting Kiribati?

Answer 57

Rising tides are contaminating water supply
People have to relocate
Rising tides being in plastic and pollution.
People keep needing to retreat due to rising sea levels.
The sea is 2 or 3 metres from the Baha’i pit (fresh water supply)
Sea walls are ineffective because they reflect back the force of the waves, just moving erosion to unprotected areas.
Population is heavily reliant on importing processed foods.
Economic migrations.

Question 58

What is a shoreline management plan?

Answer 58

Each sediment cell defines a distinct management zone for which a shoreline management plan has been written, which identifies the natural processes, human activities and management decisions.

Intervention will be largely self-contained within each cell, having little or no effects elsewhere.

Question 59

What are the key aims of SMPs (Shoreline management plans)?

Answer 59

They provide an assessment of the risks associated with the evolution of the coast.
Address risks in a sustainable way
Provide the policy agenda for coastal defence management planning.
Promote long-term management policies
Incorporate a route map
Provide a foundation for future research.

Question 60

What is hold the line?

Answer 60

Retain the existing coastline by maintaining current defences defences or building new ones where existing structures no longer provide sufficient protection.

Question 61

What is managed retreat?

Answer 61

Actively manage the rate and process by which the coasts retreats.

Question 62

What is advance the line?

Answer 62

Build new defences seaward of the existing line. (reduces stress on existing defences).

Question 63

What is no active intervention?

Answer 63

In some places, it is not technically, economically or environmentally viable to undertake defence works. The value of the built environment here does not exceed the cost of installing coastal defences.

Question 64

What are integrated coastal zone management?

Answer 64

Designed to integreate the interests of all stakeholders. - to bring all ideas together. The stakeholders are anyone effected e.g: farmers, local residents, governments and businesses.

Question 65

What are some examples of hard engineering?

Answer 65

sea walls, revetments, rock armour, groynes, cliff face strategies, offshore reefs.

Question 66

What are cliff face straetegies?

Answer 66

Pins rock layers together.
Regrading - lowers the cliff angle to make it more stable.
Drainage - removal of water prevents landslides an slumping.

It is technically difficult and drained cliffs can dry out, eading to rock falls.

Question 67

Give some examples of soft coastal engineering.

Answer 67

Beach nourishment and redistribution, dune regeneration, marsh creation and cliff regrading and drainage.

Question 68

What is marsh creation?

Answer 68

Marsh creation is a form of managed retreat, by allowing low-lying coastal areas to be flooded by the sea. The land then becomes a salt marsh.

It is relatively cheap, creates a natural buffer to powerful waves and provides an important wildlife habitat. However, agricultural land is lost and farmers or landowners need to be compensated.