Physical Geography - Coasts Flashcards
L1 Define littoral zone
From the highest water line that occurs on shore during a storm to a storm wave base
L1 What are the five parts of the littoral zone?
Coast/Land - cliffs, wave cut notches, mass movement, house building
Backshore - Upper beach, large berms, erosion
Foreshore - Swash zone, lower beach
Nearshore - surfing, fishing
Offshore - waves, currents, wind turbines
L1 Define Dynamic Equilibrium
A natural system tries to achieve a balance by making constant changes in response to influences in the system
L2 Describe a high energy coastal environment
- Long fetch
- Large energy waves
- Steep cliffs
- Storm conditions
L2 Describe a low energy coastal environment
- Small fetch
- Low energy waves
- Deposition by constructive waves
- Sandy beaches
- Buildings
L2 What is erosive resistance?
- How reactive a rock is to chemical weathering
- Whether rocks are clastic (like sedimentary) or crystalline (interlocking crystals)
- The number of cracks in a rock
L2 What is a concordant coast? What land forms happen here?
Sea is parallel to the coast, bands of resistant rocks, e.g. Coves like Lulworth Cove
L2 What is a discordant coast? What land forms happen here?
Sea is perpendicular to the coast, e.g. Headlands and Bays
L2 How do coves form?
On concordant coasts more resistant rocks erode, allowing the sea to erode the less resistant rock more quickly (e.g. Wealden Clay at Lulworth), arches formed in resistant rock cause wave refraction, spreading out wave energy & forming a circular cove
L3 What is a Dalmatian coast?
- Type of concordant coastline
- Formed as a result of rising sea levels
- Valleys and ridges run parallel to each other and ridges remain above the surface when valleys flood
- e.g. Croatian Coast
L3 What is a Haff coast?
- Concordant coastline
- Long spits of sand and lagoons aligned parallel to coast
L3 What are folds in rocks?
Formed by pressure during tectonic activity which makes rocks buckle and crumple
L3 What are faults in rocks?
When stress or pressure exceeds a rock’s internal strength causing it to fracture
L3 What is dip in a rock?
The angle at which the rock’s strata lie
L3 What is the difference between anticline and sincline?
Anticline - When strata bends in an n shape (like a sad face)
Sincline - When strata bends in a U shape (like a happy face)
L4 What happens when uniform horizontal strata make up a cliff?
- Steep cliffs
- Slow erosion
- Wave cut notches weaken rock at base of cliff
L4 What happens when there are vertical joints on a cliff?
- Joints are opened by weathering and pressure
- Rocks dip gently seaward and collapse creating talus slopes
- Erosion fairly slow
L4 What happens when a cliff has steep seaward dip?
- Shallow cliffs
- Fast erosion
- Erosion at base and rocks slip down bedding planes
L4 What happens when rocks in a cliff have a dip inland?
- Steep, stable cliffs
- Slow erosion
- Gravity pulling away from sea, holding cliff together
L4 What happens when joints in a cliff are at right angles to bedding planes?
- Areas of weakness as joints act as slip planes
- Shallow cliffs
- Medium speed erosion
L4 How do igneous rocks affect coastal recession?
- Crystalline
- Resistant
- Impermeable
L4 How do sedimentary rocks affect coastal recession?
- Formed in strata
- Can be permeable if joints are present
- Can be porous
L4 How do metamorphic rocks affect coastal recession?
- Resistant
- Impermeable
L5 Define Primary Succession
Plants and animals colonise a barren landscape
L5 Define Secondary Succession
After a major disturbance, like flooding, wildfire, landslides, or human activity, colonisation of plants/animals begins
L5 What are embryo dunes?
- Form first and collect sand
- Pioneer plants colonise the stable dunes (e.g. Prickly Saltwort) and hold sand together
L5 What are yellow dunes?
- Highest and form a ridge with marram grass
- Not fully vegetated
- Subject to alterations by wind/waves
L5 How can high tides or storms help succession?
Seawater may reach dips (slacks) allowing other plants such as Marsh Orchids to grow
L5 What is climax vegetation?
Final type of plants that colonise when there is a balance between natural factors
L5 What are salt marshes?
- Low energy environments of estuaries, sheltered bays, or behind spits
- Tides bring seawater and sediment in/out, rivers bring mud & silt and deposit them
L5 What is flocculation?
Tiny clay particles stick together and are colonised by algae
L5 What is Halosere Succession?
- Pioneer plants survive salty water twice a day
- As salt marsh grows, gets covered less
- This and rain leaches salt from soil, making it fertile for bigger plants to grow
L5 Define Halophytic
Plants that naturally inhabit saline environments
L7 Summarise destructive waves
- More energy waves
- Strong backwash
- Weak Swash
- Highly erosive
- High frequency (10-14 wpm)
L7 Summarise constructive waves
- Less energy
- Weak Backwash
- Strong Swash
- Depositional
L7 What are factors that affect wave size?
- Fetch
- Wind direction
- Depth
L7 What beach profile do destructive waves create?
- Berms eroded
- Strong backwash creates offshore bars
- Backwash exerts rip - dragging sedimentary back as next wave arrives over top
L7 What beach profile do constructive waves create?
- Steeper beaches
- Berms at top of beach due to Swash
- Backwash becomes weaker as berm builds
- Less energy so material is smaller towards the shoreline
L8 Give the 4 types of erosion and define them
Abrasion - pebbles hurled at the cliff base by the waves causing erosion
Hydraulic action - waves cause air to be trapped in joints at high pressure which ‘explodes’ outwards as the waves retreat
Attrition - Wearing down of rocks by impact, gradually making stones rounder and smaller
Solution - Alkaline cliffs (chalk, limestone) are eroded by weakly acidic seawater
L8 What 2 things cause different rates of erosion?
Energy in waves, lithology - joints, bedding planes, faults, resistance - leading to differential erosion
L8 Describe how a wave cut platform is formed
Waves erode away the base of the cliff, cliff becomes unstable and collapses, rock is broken up and used in attrition to erode away the new cliff, cliff retreats
L9 Describe the 4 processes of marine transportation
Suspension - lighter sediment floats
Traction - large, heavy rocks roll along the seabed
Solution - dissolved sediment
Saltation - smaller rocks bounce along the seabed
L9 Describe the process of Longshore Drift
Swash hits the coast at an angle due to the prevailing wind, backwash is perpendicular to the coast due to gravity, sediment is transported up the beach
L9 Describe the formation of a spit and give an example
Longshore drift causes sediment to travel along a coast until the coast suddenly changes direction (e.g. an estuary), if this happens sediment is deposited, the end of a spit will begin to curve round due to wave refraction which carries material into the more sheltered water behind the spit, e.g. Spurn Point
L10 Describe the formation of a beach, give examples
Accumulation of sand/shingle, formed due to constructive waves, swash carries material up the shore but backwash has little energy so material is deposited, e.g. WSM, Blackpool, Southend
L10 Describe the formation of an offshore bar and give 2 examples
Sediment is eroded by destructive waves and deposited by backwash, located at offshore/nearshore boundary where the water particle orbit no longer reaches the seabed, used to construct wind farms or as a source of sand for beach nurishment, e.g. Loe Bar, Cornwall or Slapton Sands, Devon
L10 Describe what a bar is, give two ways they’re formed, and give an example
Linear ridges of sand that extend completely across a bay, e.g. Chesil Beach
Formed in 2 ways:
- LSD extends a spit across the width of a bay
- Rising sea levels cause constructive waves to drive a ridge of sediment onshore to coastlines with a gently sloping shallow sea bed (barrier beach)
L10 Describe what a tombolo is, 2 ways they can form, and give examples
Linear ridges of sand connecting an offshore island to the coastline, e.g. St Ninian’s tombolo, Shetland Islands or Portland Bill
Formed by:
- LSD which builds a spit which connects to the island
OR
- Wave refraction around both sides of the island, creates a collision of waves which cancel each other out, creates a still environment where deposition takes place
L10 Describe what a Cuspate Foreland is, how they’re formed, and give an example
Low lying triangular headlands extending out from the shoreline, e.g. Dungeness Kent (11km)
LSD currents from opposite directions converge at the boundary between two sediment cells, sediment is deposited out into the sea by both currents
L11 Describe the UK’s sediment cell system
Sediment is transported throughout the 11 UK sediment cells without crossing between them, ‘sediment budget’ within each cell, sediment is in a state of ‘dynamic equilibrium’ in each cell
L11 Give the 3 types of mechanical weathering
Freeze-thaw - water gets into the cracks of rocks and freezes in cold weather, expands by 10% volume, this expansion exerts pressure on the rock which forces the cracks to widen, after repeated cycles rocks break away and collect at the bottom of the cliff as talus
Salt-weathering - salt water evaporates leaving salt crystals behind, these exert stresses in the rock, causing it to break up after repeated cycles
Wetting and drying - frequent cycles of rain and dry means rocks rich in clay (e.g. shale) expand when they are wet and contract when dry, this causes them to crack & break up
L11 Describe some examples of biological weathering
- Thin plant roots get into cracks of rocks and expand as they grow
- Water running through decaying vegetation becomes acidic and leads to chemical weathering
- Birds/other animals burrow/dig into cliffs
- Marine organisms burrow into rocks (e.g. Piddocks) or secret acids (e.g. Limpets)
L11 Give and explain the 1 example of chemical weathering
Carbonation - rainwater absorbs CO2 from the air to form a weak carbonic acid, this reacts with calcium carbonate (in rocks like Limestone or Chalk) to form calcium bicarbonate, this is increased in winter as the cooler the rainwater, the more CO2 is absorbed
L12 Describe 3 types of flows (mass movement)
- Soil Creep - slowest form of mass movement, an almost continuous process, very slow downhill movement of soil particles
- Solifluction - 5cm-1m a year, tundra areas, top layer thaws in summer, layer below remains frozen, surface layer flows over the permafrost
- Earth flows and mudflows - increase in water reduces friction, causes earth and mud to flow over bedrock, in a flow the material becomes jumbled up
L12 Describe 2 types of slides (mass movement)
- Rockfalls - Strong, jointed, and steep rock faces exposed to mech. weathering, slopes over 40°, material bounces to form talus, block falls are similar - large blocks of rock fall due to jointing of the cliff
- Rock/Debris slide - Rocks that are jointed/bedding planes parallel to slope are susceptible, increase of water reduces friction, slabs of rock slide over underlying rocks
L12 Describe Slumps (mass movement)
Often saturated conditions, rotational movement (not sliding), moderate steep slopes, common where softer materials overlie resistant rock, can create a terraced cliff profile after repeated slumping
L12 Give an example of mass movement on the Jurassic Coast
Apr. 2021 - major landslide between Seatown and Eype, 300m of cliff (4000 tonnes) collapsed into the sea
- During wet 2021 winter, water infiltrated the permeable sandstone and reached the impermeable clay, water built up in the sandstone making it heavier, top of the clay became more slippery, sandstone dried up and lost strength, gave way due to gravity & slippery clay
L13 What are the 2 reasons why sea levels are currently rising?
Land ice melting, geothermal expansion of the ocean
L13 What is the difference between eustatic and isostatic sea level change?
Eustatic - sea level rises/falls itself
Isostatic - land itself rises/falls compared to the ocean
L13 Describe how isostatic change occurs in the UK
During glacial periods the weight of the ice on Northern areas pushed the land into the mantle (isostatic subsidence), as the ice melted the land readjusted and rose (isostatic recovery), due to the location of the glaciers the UK is tilting and London is sinking
L13 Describe landforms created by changing sea levels on emergent coastlines, give examples
Raised beaches - where eroded cliff lines (relic cliffs) can be found behind the raised beach, with wave cut notches and caves as evidence of past marine erosion, e.g. Raised Beach at Portland Bill, Relic Cliffs on Isle of Arran, Scotland
L13 Describe landforms created by changing sea levels on submergent coastlines, give examples
Rias - flooded river valleys in upland areas, sea levels rose in SW England after ice age drowning the lower parts of the river, e.g. Milford Haven, Pembrokeshire
Fjords - U-Shaped valleys flooded, much deeper inland than at the coast, e.g. Milford Sound, NZ
Dalmation Coasts - Similar to rias but rivers flow parallel to the coast rather than at right angles, e.g. Croation Coast
L13 Describe how sea level change can happen due to tectonic activity, give an example
-Tsunamis have an impact on sea level
e.g. 2004 Boxing Day Tsunami killed 300,000:
- Wave itself caused flooding
- Earthquake caused crust to sink in Banda Aceh
- Seabed rose where the undersea slip occurred
L14 How fast is the Holderness coast retreating? How far has it retreated since Roman times? How many villages have been lost?
2m a year, retreated 4km since Roman times, 29 villages lost
L14 What are the 4 factors that explain why coastal recession is so great along the Holderness Coast?
Geology - boulder clay isn’t resistant and is prone to erosion & mass movement
Fetch - 500-800km fetch, deep ocean so less friction, currents circulate from Atlantic
Sub-Aerial processes - weathering & mass movement, chem. weathering at FH, bio. and phys. weathering in boulder clay & chalk
Long-shore drift
L15 Describe what is happening at Withernsea in terms of social and economic losses due to coastal erosion
- Many holiday parks which lose tourism
- 200 homes and several roads will fall into the sea by 2100 (7000 nationally by then)
L15 Why is the local council at Withernsea better than the govt for cases of lost property due to coastal erosion?
There is no compensation for loss of property due to coastal erosion in England
2010-12 - East Riding of Yorkshire council used £1.2m to trial support:
- 36 households received financial assistance
- 16 relocations & 43 demolitions were supported
L15 Describe the social and economic damages of coastal erosion in Happisburgh, Norfolk
Happisburgh is on Norfolk’s North Sea coast, 1400 population & 600 houses
Social: 14th C. church, manor house, and famous lighthouse at risk, tragic floods in 1953 killed 76, 250m of land lost 1600-1850
Economic: Coastal defences have slowed the rate but some in disrepair, agriculture & tourism industries lose out significantly, prior to a new rock embankment the receding cliff claimed 1 property & lots of agricultural land per year
L16 Why does Mappleton need protecting?
- Population of 342
- 30 homes at risk
- B1242 road links Hornsea to Withernsea
L16 Describe what groynes are, what advantages and disadvantages they have, and how much they cost
Groynes are wood/rock structures at right angles to the coast to trap sediment moved by LSD
+ves - Built up beach increases tourism, protects land behind it, cheap
-ves - starves beaches further along the coast of sediment - increased erosion
Cost - £5k-10k each (200m intervals)
L16 Describe what sea walls are, what advantages and disadvantages they have, and how much they cost
Sea walls are stone/concrete structures that reflect wave energy
+ves - Effectively prevents erosion, promenade to walk on
-ves - Reflect energy, don’t absorb it, intrusive & unnatural, expensive to build & maintain
Cost - £6k a metre
L16 Describe what rip rap (rock armour) is, what advantages and disadvantages it have, and how much it costs
Rip rap is large rocks that act as a permeable barrier to the sea
+ves - Cheap & easy to construct & maintain, used for fishing & sunbathing
-ves - Rocks from elsewhere (e.g. granite) so unnatural, dangerous
Cost - £100k-300k for 100m
L16 Describe what revetments are, what advantages and disadvantages they have, and how much they cost
Revetments are sloping wood/concrete/rock structures that break up wave energy
+ves - Inexpensive to build
-ves - Intrusive, high maintenance
Cost - £4.5k a metre
L16 Describe what offshore breakwaters are, what advantages and disadvantages they have, and how much they cost
Offshore breakwaters are partly submerged rock barriers that break up waves
+ves - Effective permeable barrier
-ves - Usually unappealing, potential navigation hazard
Cost - Similar to rock armour (depends on materials)
L16 What is terminal groyne syndrome? Give an example
When groynes cause increased erosion further down the coast because they starve the beaches of sand, e.g. Groynes at Hornsea starved Mappleton of sediment - by 1990s, 4m of cliff eroded yearly
L17 What is an ICZM?
Integrated Coastal Zone Management (ICZM) is a strategy designed to manage complete sections of the coast rather than individual towns/villages
L17 What is a SMP?
Shoreline Management Plans (SMPs) - set out a national strategy for a flood and coastal defence in E&W, based on the 11 sediment cells
L17 What are the 4 ways coastal defences and management are judged in ICZM?
- Hold the line - maintain/upgrade defences
- Advance the line - more defences significantly seawards
- Management realigned of the shoreline - change position of shore in a controlled way
- No active intervention
L17 Give the details of the East Riding of Yorkshire Council’s ICZM
Launched in 2002, involved 80 organisations, sediment cell between Flamborough Head and Gibraltar Point, plan to aid prevention of coastal erosion, invest in flood risk management, and involve all affected players
L18 Why is Bangladesh vulnerable to flooding? (4 reasons)
- Most densely populated country - 169m
- 46% of pop. lives less than 10m above sea level
- Floodplains of 3 major rivers with sources in the Himalayas
- Coastal and river flooding is common due to monsoon rains, high tides, snow melt, and cyclones
L18 Why are Bangladesh’s estuarine islands at risk?
The low-lying estuarine islands are at risk because it is sinking relative to the rising sea levels and within 100 years will be completely underwater. Cyclones and storm surges make flooding more common which damages crops and contaminates the local soil and drinking water with seawater.
L18 What are mangroves and why are they so important?
- Mangroves are tropical plants that withstand tides, salt water, & wet soil.
- Protect populated areas from erosion and storm surges.
- Provide habitat for fish, birds, insects, and reptiles.
- Absorb 4 times more carbon than normal forests
L18 What is happening in Gazi Bay, Kenya with the mangroves?
Sustainable management project restores mangroves for coastal protection, biodiversity, and carbon sequestration. Involves local community in conservation efforts & has generated $60k towards local schools & protection against illegal loggers
L19 Describe storm surges
Changes in sea level caused by intense low pressure systems
- For every 1mb drop in pressure, sea level rises by 1cm
- Intensified by funnel-shaped coastlines
L19 Summarise Cyclone Sidr
- 15th Nov. 2007
- Formed over Bay of Bengal, cat. 4
- 5m high storm surge
- Many coastal regions worst affected
L19 What were the social, economic, and environmental impacts of Cyclone Sidr?
Social:
- 3000 died
- Hundreds of thousands displaced - some temporarily, some permanently
- Rise in waterborne diseases, e.g. cholera
Economic:
- $1.5bn total damage
- 2.5m acres of cropland, 300,000 livestock killed
- Fishing industry lost $50m revenue
Environmental:
- Erosion rates accelerated - 10-15m in some places
- Over 20,000 hectares of mangrove forest destroyed
L19 Why were the casualties of Cyclone Sidr less than expected?
Early warning systems, good evac. plans, and better preparedness e.g. improvements in forecasting tech.
L19 What strategy was put in Bangladesh to prevent the effects of storm surges? Why was it controversial?
Embankments built to protect villages from the sea - controversial because they allow water to build up behind it making it more destructive and powerful when a storm surge breaks through
L19 Describe the storm surges in UK Dec. 2013-Jan. 2014
Stormy conditions, heavy rain, coastal flooding, and storm surges
Caused by a deep low pressure system (5th-6th Dec. 2013) over North Sea, strong winds (130km/hr), and highest tides of the month
L19 Give the social, economic, and environmental impacts of the 2013 UK storm surges
Social:
- 2 deaths
- Thousands evac. in flood-prone areas
- Damage to homes, schools, & public infrastructure
Economic:
- 1000 properties flooded
- thousands of acres of farmland destroyed
- £100m total damage
Environmental:
- Saltwater damaged wetlands, salt marshes, and coastal habitats
- Significant coastal erosion - 10m in some places
L19 Give evidence that tropical storms are increasing in intensity and frequency
- Cat. 4 & 5 hurricanes make up 30% of total hurricane activity in the Atlantic vs. 20% in mid-20th C.
- Frequency of Atlantic hurricanes has increased by 25% since 1900
L19 What happened in 2014 with NZ and other Pacific Island nations?
In 2014, Cyclone Pam caused damage to islands like Vanuatu and the Solomon Islands (250km/hr winds), NZ committed significant funds to help and this humanitarian aid is expected to grow in the coming decades
NZ also has had discussions with Kiribati about land deals due to the nations issues surrounding rising sea levels
L20 What are the characteristics of Odisha’s coastline?
- 480km coast along Bay of Bengal, mostly low-lying
- 1435 sq. km of mangrove forests, 82 species, 1/4 largest in India
L20 How is the coastal zone of Odisha being protected?
ICZM: sustainable development of the coastal area while maintaining ecosystem preservation and tourism in the form of ecotourism, solid waste management plant in Paradip City, monitoring of coastal pollution
L20 Summarise the Odisha ICZM. Why is the coastal zone of Odisha important?
Odisha Coastal Management Authority oversees the project, helped with funding from the world bank, the plan has aimed to protect coastal habitats whilst also developing sustainably
The area is important because of ports (e.g. Paradip Port), tourism (e.g. Chilika Lake - Asia’s largest coastal lagoon), mangroves acting as a natural buffer against storm surges & cyclones
HW What coastal policies have been brought in at Happisburg?
- £1.4m for ‘purchase and lease back’ of 11 houses on Beach Rd
- Owners offered 1/2 their ‘non-blighted’ value of property
- Beach Rd properties demolished & a buffer zone created
- Campaigning by Coastal Concern Action Group (CCAG) has led to the area being designated as ‘managed realignment’ so future defences are allowed if funding can be found
HW Who are the winners and losers in Happisburg?
Winners:
- Locals w/ properties at risk
- CCAG
- North Norfolk District Council (allocated £3m for local area)
Losers:
- Homeowners (only offered 1/2 of their property value)
- Government (had to allocate funding)
- Local habitats (lost due to ‘coastal squeeze’)
HW What coastal policies have been brought in at Chittagong, Bangladesh?
- Raising embankments to 60cm above normal flood levels & making them more resistant to erosion
- New market areas on platforms above expected 2050 sea levels
- Constructing/building 25 cyclone shelters
- Training in climate resilience & adaptation
HW Who were the winners and losers at Chittagong?
Winners:
- Locals (poverty alleviated 10%, income opportunities, adapted to climate change)
- Businesses & markets (roads flooded for 5 days a year rather than 20)
Losers:
- Natural habitats (permanent removal of vegetation)
- Some households (200 relocated due to road realignments)
