✅3.1.3.3 - Coastal Landscape Development Flashcards
How is a wave cut platform formed?
Waves breaking at foot of cliff form wave cut notch
Undercutting is result of erosion by waves
As undercutting continues, rock above collapses and cliff gradually retreats
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 wave’s 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, slow
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 unconsolidated rock
How does rockfall occur?
Sudden form of collapse or breaking away of rocks from a cliff face
How is a stack formed?
Headland is attacked by waves along lines of weakness
The erosion exploits a weakness, forming a cave
If the weakness runs through the headland, two caves may form back to back
Eventually an arch is formed
Wave attack continues at the base of the arch until it collapses, 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
When do beach cusps occur?
Where the coarser material at the top of the beach absorbs wave swash
Where do bay bars form?
Across estuaries, blocking off rivers
Where do barrier beaches form?
Where waves recycle offshore material
How do swash aligned beaches develop?
When waves break parallel with the coast, the movement of water an material is largely up and down the beach.
What are tombolos?
When spits extend from the coasts to an island
What are cuspate forelands?
Triangular shaped features which may have resulted from changes in the growth and direction of spits.
When does deposition occur?
When there is insufficient energy to move sediments further in low energy environments
Where do runnels form?
Close to low water marks, separating pools of standing water at low tide
Where do ripples form?
Small marks that appear where the slop of the beach increases and where the tide moves over the beach
How does pebble size change up the beach?
Bigger, heavier pebbles are found further up the beach because more energy is required to transport them. Smaller lighter ones are further up to the backshore.
What are the features of swash aligned beaches?
Beaches can be large, especially if facing into 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 beaches?
Pebbles and sand drift along because in wind direction
Landforms created by material moved along beach by LSD
What is a spit?
A long, narrow feature that extends from the mainland at the end of a drift aligned beach
Why does a recurved end occur?
Wave refraction and a second dominant wind force material to move in a different direction
What are examples of tombolos?
Isle of Purbeck, UK
Angel Road, Shodo Island
In what conditions do tombolos form?
Island close to mainland Area of shallow water Preferential supply of sediment (cliff erosion) Small, low energy waves Sheltered area Consistent prevailing wind
When is an offshore bar formed?
When material is built up parallel to the coast
When is a barrier beach formed?
If a bar reaches a headland and the body of water behind it is cut off.
What are examples of barrier beaches?
Slapton Sands, Devon, UK
Cies Islands Bar, Spain
What 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?
Scolt Head Island, Norfolk, UK
Padre Island, Texas
How are sand dunes formed?
Sand accumulates on beach from longshore drift
At low tide, sand dries out, allowing prevailing wind to move it up beach
Larger intertidal range for sand to dry
Sand transported by saltation
Debris on beach traps it
Grasses grow and stabilise dunes
What is the strand line?
Where debris traps the sand to begin forming a dune
What is fluid threshold velocity?
The amount of energy the wind must have to move the sand on a beach
What are the stages of dune formation?
Embryo dune Fore dune Yellow dune Grey/Fixed dune Dune slack Mature dune/heath
What are the features of embryo dunes?
Sand continually moving - needs obstruction to break force of wind
High pH and wind sped
Lots of salt spray, less the 1m tall, exposed