Coastal landscape Development Flashcards
How is a wave cut platform formed? (4)
1) waves break at foot of cliff from a wave-cut notch
2) Undercutting rock as a result of erosion by waves
3) As undercutting continues, rock above collapses and cliff gradually retreats
4) A sloping rocky platform is left behind, the wave cut platform, covered at high tide
What effect do wave cut platforms have on the rate of erosion?
- They affect the waves ability to erode the cliff because they have further to travel in shallow water
- they break earlier and dissipate their energy, reducing rates of erosion
How does soil creep occur?
Slow form of movement of individual soil particles moving down a hill or slope
How does mudflow occur?
Earth and mud flowing down a slope or hill
How does run off occur?
A type of flow from one store (rockface) to another (beach or sea)
How does landslide/ slump occur?
Where material slides on a curved surface over weak and unsolidated rock
How does rockfall occur/
Sudden form of collpase or breaking away from rocks from a cliff face
Where are 2 examples of wave cut platforms OUTSIDE the UK?
Collaroy Beach, NSW, Australia
Fisherman’s Rock, NZ
Where are 2 examples of cliffs located outside the UK?
Ketbjorg Cliffs, Iceland
Dryholaey, Iceland
Where are 2 examples of caves located outside the UK?
Puntq de Arucas, Spain
Waiahuakua Cave, Hawaii
Where are 2 examples of arches located outside the UK?
Es Pontas Arch, Mallorca, Spain
The azure Window, Malta
Where are 2 examples of stacks located outside the UK?
Stacka in Dryholaey, Iceland
12 apostles stack, Australia
How is a stack formed? (5)
1) Headland is attacked by waves along lines of weakness
2) The erosion exploits weakness, forming a cave
3) If the weakness runs through the headland, 2 caves may from back to back
4) Eventually an arch forms
5) Wave attacks continues at the base of the arch until it collapsed, leaving a stack
How is a stump formed?
When a stack is continually eroded until it collapses
In what conditions do sand dunes form?
When dry material from flat, open beaches is blown inland
In what conditions do mudflats and salt marshes form?
When finer material sticks together in the shallow water of estuaries
When do beach cusps occur?
When the coarser material at the top of the beach absorbs wave swash
Where do bay head beaches build up?
In sheltered, low energy environments of coves. Wave refraction focuses erosion on the surrounding headlands, encouraging deposition in the bay
Where do bays form?
Bays form across estuaries, blocking off rivers
Where do barrier beaches (bars) form?
Bars form where waves recycle offshore material
How do drift-aligned beaches develop?
Where waves approach the coastline at an angle, the swash moves material up the beach in that direction, and the backwash returns at right angles (LSD)
A range of partially detached features are formed
How do swash-aligned beaches develop?
when waves break parallel with the coasts, the movement of water and material is largely up and down the beach
What features arise from swash-aligned beaches? (3)
Bay head beaches
Bay bars
Barrier beaches
What features devlop from drift aligned beaches? (4)
Spits
Recurved spits
Tombolos
Cuspate forelands
What are tombolos?
When a spit extends from the coast to an island
When does deposition occur?
When there is insufficient energy to move sediments further in low-energy environments
How does pebble size change up the beach?
Bigger, heavier pebbles are found further on the beach because more energy is required to transport them. Smaller lighter ones are further up the backshore
What are the features of swash aligned beaches? (3)
- Beaches can be large, especially if facing onto prevailing wind
- Landforms are created by offshore sediment
- Found right at the back of bays due to wave refraction
What are the features of drift aligned becahes?
Pebbles and sand drift all the way along because of the wind direction
Landforms: spits, bars and tombolos
What is a spit?
A long, narrow feature that extends from the mainland at the end of the drift aligned beach when prevailing wind blows at an angle to the coastline
Why does a recurved end occur?
Wave refractrion and a 2nd dominant wind force moves material in a different direction
What are examples of tombolos?
Isle of Purbeck, UK
Angel Road, Shodo Island
In what conditions do tombolos form? (6)
Island close to the mainland
Area of shallow water
Preferential supply of sediment (cliff erosion)
Small, low-energy waves
Sheltered area
Consistent prevailing wind
when are offshore bars formed?
Offshore bars are formed when material is built up parallel to the coast
When are barrier beaches formed?
If a bar reaches a headland and the body of water behind is cut off
What are examples of barrier beaches?
Slapton Sands, Devon, UK
Cies Island Bar, Spain
What’s are barrier islands?
Islands formed parallel to the coastline but not touching it, a lagoon may form behind
What are some examples of barrier islands?
Scoot Head Island, Norfolk, UK
Padre Island, Texas