Coasts

Question 1

What is a sediment cell and how many are there in England and Wales?

Answer 1

An area along the coastline and in the nearshore area where the movement of material is largely self contained, with the boundaries of the cells being headlands or areas of deep water (estuaries)

11 in England and Wales

Question 2

What is a current?

Answer 2

The permanent or seasonal movement of surface water in the seas and oceans

Question 3

What is a longshore current?

Answer 3

Most waves hit the coastline at an angle which generates a current running parallel to the shoreline

Question 4

What are rip currents?

Answer 4

Strong currents moving away from the shoreline which develop when water is piled up along the coastline by incoming waves

Question 5

What is upwelling?

Answer 5

The movement of cold water from deep in the ocean towards the surface

Question 6

What are tides?

Answer 6

The periodic rise and fall in the level of the sea caused by the gravitational pull of the Sun and Moon

Question 7

What is a spring tide?

Answer 7

When the pull of the moon and sun are aligned in the same direction which causes a larger tidal range than usual

Question 8

What is a neap tide?

Answer 8

When the sun and moon are perpendicular to each other so their gravitational forces act against each other. This causes smaller tidal ranges than usual.

Question 9

What is the offshore?

Answer 9

The area beyond the influence of waves

Question 10

What is a tidal surge?

Answer 10

When a storm surge is combined with a high tide (usually spring tide)

Question 11

What is the fetch?

Answer 11

The distance of open water over which wind blows uninterrupted by major land obstacles

Question 12

What is wave refraction?

Answer 12

The process by which waves bend as they approach an irregular coastline, causing energy to be concentrated on headlands and dissipated in bays

Question 13

What are landslides?

Answer 13

Soft loose rock moves down a cliff very quickly as a result of lubrication (heavy rainfall)

Question 14

When do rockfalls occur?

Answer 14

When cliffs are undercut by the sea or on cliffs where physical weathering has taken place

Question 15

What are mudflows?

Answer 15

When heavy rain mixes with fine sediment and flows down a hill

Question 16

What is rotational slumping?

Answer 16

When soft, permeable material lies over hard, non-permeable material. Rainfall causes the upper section to become saturated and this added weight causes large sections of the cliff to slump and rotate.

Question 17

What is aeolian deposition?

Answer 17

The process by which wind transports and deposits sediment

Question 18

What is soil creep?

Answer 18

The slow downward movement of soil on a slope due to gravity. When soil is wet, it expands horizontally and when it dries it contract vertically, pulling the particles downhill

Question 19

What is the difference between compound and simple spits?

Answer 19

Compound spits have multiple recurved ends while simple spits have no recurved ends. Recurved ends form due to a secondary wind direction or a fast flowing body of water (eg. river)

Question 20

What is a Shoreline Management Plan (SMP)?

Answer 20

A strategic plan for managing flood and erosion risks along a stretch of coastline over short, medium and long term periods. 4 different strategy options: do nothing, managed retreat, hold the line, advance the line. There are 20 covering the English coast

Question 21

How much are sea levels expected to rise by 2100?

Answer 21

0.8-1.2 m

Question 22

What are the characteristics of constructive and destructive waves?

Answer 22

Constructive - lower energy and wave height, long wavelength, low frequency (6-8/min), stronger swash, weaker backwash
Destructive - higher energy and wave height, short wavelength, high frequency (10-14/min), weaker swash, stronger backwash

Question 23

Outline sub-aerial weathering

Answer 23

• The breakdown of rocks in situ
• Physical (freeze thaw)
• Biological (roots grow into cracks)
• Chemical (carbonation, solution)

Question 24

What is wave quarrying, corrasion and cavitation?

Answer 24

Wave quarrying - when the power of high energy waves enlarges joints and removes large chunks of rock in one go
Corrasion - abrasion
Cavitation - compression of air in cracks, causing sea water to be compressed which causes bubbles eventually to implode, creating a small shockwave

Question 25

Outline landforms on the Jurassic coast

Answer 25

Swanage coastline is discordant with hard limestone and chalk, and soft clays and sands - Wave cut platform -> one at Old Harry Rocks - Arches, stacks, stumps -> Old Harry Rocks (Old Harry = stack) (wife = stump) - Cove -> Lulworth Cove (band of limestone parallel to the coast, behind which were various clays) - Bays and headlands -> Durlston Bay and Headr

Question 26

What are swash aligned and drift aligned beaches (with examples)?

Answer 26

- Swash - waves approach perpendicular to the shore -> eg. Lulworth Cove - Drift - waves approach at an angle, allowing for LSD -> eg. Swanage Bay

Question 27

What are examples of simple and compound spits?

Answer 27

Simple - Farewell Spit, New Zealand Compound - Hurst Spit, Hampshire

Question 28

What is a tombolo (with example)?

Answer 28

When a spit has extended and joined an island - eg. Angel Road, Japan

Question 29

What is a bar/barrier beach (with example)?

Answer 29

When a spit joins another headland -eg. Loe Bar, Cornwall

Question 30

What is an offshore bar (with example)?

Answer 30

- A submerged or partially exposed ridge of sand/shingle running parallel to the coast - Formed from sediment eroded by destructive waves and carried seawards by backwash, depositing sediment offshore - Eg. Scroby Sands, Norfolk

Question 31

How do sands dunes form (with example)?

Answer 31

- They form due to saltation and aeolian deposition causing sand to build up against an obstacle - Over time, halophytes such as marram grass will colonise the dune, holding it together and stabilising the dune - This dune then acts as an obstacle for another dune to form and the process repeats to create a sand dune system - Over time, the dunes furthest from the salty seawater will also become colonised by plants like lichens and a vegetation succession will form - Example is Ainsdale Sand Dunes near Liverpool

Question 32

How do mudflats and salt marshes form (with example)?

Answer 32

- Mudflats form in sheltered areas along the coastline which are regularly flooded by tides such as behind spits - They form due to the deposition of mud and silt, and over time this process will repeat, causing the mudflat to grow - Pioneers that are halophytes such as cordgrass will begin to colonise the mudflat - As flooding continues, the mudflat will grow taller due to increased deposition and vegetation trapping sediment - The mudflat will become less saline due to less flooding as it is taller, allowing more vegetation such as marshgrass to colonise the mudflat, transforming it into a salt marsh and forming a vegetation succession - Eg. Keyhaven Saltmarsh behind Hurst Spit

Question 33

What is eustatic sea level change?

Answer 33

A change in the global ocean level, caused by changes in the total volume of water and thermal expansion

Question 34

What is isostatic sea level change?

Answer 34

A localised change in sea level when the land mass moves relative to the sea (eg. isostatic rebound in Scotland after glaciers weighed down on the land)

Question 35

How do rias form (with example)?

Answer 35

- During glacial periods, basal meltwater forms large river channels via erosion - As temperatures rise and ice melts eustatic sea level rise occurs which floods the river channels, forming a ria - Eg. Sydney Harbour

Question 36

How do fjords form (with example)?

Answer 36

- Ice moves over rough land due to basal meltwater providing lubrication - In the night, meltwater freezes which causes rocks to be ‘plucked’ and attached to the ice - When the ice moves again, the rocks scrape against the land by abrasion which leaves behind a glacial trough with U-shaped sides - When eustatic sea level rise occurs, these troughs are flooded, forming fjords - Eg. Milford Sound, New Zealand

Question 37

How do raised beaches form (with example)?

Answer 37

- Raised beaches form at areas which were covered by thick ice sheets during the last glacial period - This caused the land to be pushed down and after the ice melted, the land slowly rebounds -> isostatic rebound - When there are beaches at these areas, the land rises faster than the sea which causes the old beach to be stranded above the current shoreline - Landforms such as wave-cut platforms remain, and relict cliffs are cliffs above the wave action - Eg. St Andrews, Scotland -> raised beaches, wave cut platforms, relict cliffs, land risen 100m since last glacial

Question 38

How long does it take wave cut platforms to form, how steep are they and how large can they become

Answer 38

- Hundreds to thousands of years - Around 4 degrees - 500m is the limit

Question 39

What is the SMP strategy at Hengistbury Head and what management is in place?

Answer 39

- Managed realignment (allowing the coastline to move backwards in a controlled way) for all units except the long groyne - Long Groyne (upgrade finished in October 2024) made 1.5m higher protecting up to 6000 homes, Rock Groynes on Mudeford Spit, nothing along the beach

Question 40

What is Integrated Coastal Zone Management (ICZM)?

Answer 40

A broad, holistic framework for sustainable management of the entire coastal zone, balancing human and economic needs with natural processes.

Question 41

What is the difference between SMPs and ICZMs?

Answer 41

- ICZM covers the entire coastal zone, recognising interaction between different cells. Also takes a more holistic approach, taking into account economy, wildlife etc. to a greater extent and involves more and a wider range of stakeholders - SMPs only apply to shoreline sections and cells are considered as closed systems. Focuses mostly on erosion and flood risk

Question 42

What are possible feedback loops at Hengistbury Head?

Answer 42

Negative - if erosion causes a cliff to collapse, it may deposit large amounts of debris at the base, protecting the base from further wave attack, slowing the rate of erosion Positive - if storms damage or humans trample on sand dunes, vegetation will be weakened, meaning sand can be blown away more easily. This will further weaken dunes