Theme 2 Chapter 1 - Coasts Flashcards
What is the difference between constructive waves and destructive waves?
Constructive: Helps build up a beach
Strong swatch, Weak backwash
Destructive: Helps erode the beach
Strong backwash, weak swash.
What is the fetch?
The distance a wave travels before hitting a coastline
How does the geology of the coastline affect the rate of erosion?
Made of soft rock: high rate of erosion
Made of Hard rock: Slower rate of erosion
What are the 4 types of erosion?
Hydraulic action: the force of water eroding a coastline
Abrasion: the water picking up rocks to help erode the coastline
Attrition: Rocks colliding and eroding each other
Corrosion: chemicals processes eroding coastlines (like acid rain)
What is mass movement?
The downhill movement of of materials (rock, rock, mud and sand)
What are the 4 types of mass movements?
Rockfall: Fragments of rock fall off the cliff -often due to freeze-thaw weathering
Landslide: Blocks of rocks fall downhill
Mudflow: Saturated soil and weak rock flow down the slope
Rotational slip: Saturated soil and weak rock flow along a curved surface
What are the type of transportation?
Suspension: The smallest particles easily carried by stream
Solution: Materials from rocks dissolved in water
Saltation: Larger particles bounce along seabed
Traction: The largest materials are dragged along the seabed
How are wave-cut platforms formed?
1) Destructive waves hit between the low and high tide points, undercutting the cliff
2) This leaves an overhanging cliff which falls due to gravity
3) The cliff retreats back leaving a wave-cut platform
How are cave, arch, stack and stumps formed?
1) Weakness forms in the base of a headland due to destructive wave
2) The weakness forms a cave due to undercutting
3) The cave turns into an arch and it collapses due to gravity forming a stack
4) Stack collapses leaving a slump
How are beaches formed?
- Through decomposition
- made of eroded materials which have been deposited by constructive waves
How are spits formed?
1) Prevailing winds move materials up the beach and materials move down the beach due to gravity (materials are moved in a zig zag movement across the beach)
2) Materials are deposited in shallow calm waters to form spits
3) the direction of the spit is determined by the direction of the wind
What is longshore drift?
1) Waves approach beach at an angle due to prevailing winds
2) Materials are moved up the beach in the swash
3) Materials are carried down the beach in the backwash due to gravity
What is the difference between soft engineering and hard engineering?
Soft engineering is where the natural environment is used to reduce wave energy and reduce coastal erosion.
Hard engineering is where sea defenses are used to reduce wave energy and prevent coastal erosion.
What coastal defenses are considered soft engineering and hard engineering?
HARD: Sea walls Groynes Rock armor Gabions
SOFT
Beach nourishment
Beach stabilisation
Wetland creation
What are advantages and disadvantages of the hard engineering methods?
SEA WALLS:
Adv: Effective
Dis: Expensive
GROYNES:
Adv: helps widen beach
Dis: Can prevent longshore drift causing conflict
ROCK ARMOR:
Adv: Helps prevent undercutting of the coast
Dis: Can be dangerous for children
GABIONS:
Adv: cheapest option
Dis: Make beach an eyesore
