Physical Landscapes (UK) Flashcards
Why are some waves larger than others?
Stronger wind
Longer fetch
What is the top and bottom of the wave called?
Peak and trough
Describe how the wave breaks as it reaches the shore
The wave has a circular orbit
Friction with the sea bed distorts orbit
Top of wave moves faster
Wave breaks
What is the difference between a constructive and destructive wave?
Constructive has a strong swash and weak backwash
Destructive has a weak swash and strong back swash
Name 3 characteristics of constructive waves
Flat beaches
Carries material up beach (transportation)
Far apart in length
Under 1m
Name 3 characteristics of destructive waves
Over 1m
Steep beaches
Breaks downward with force
Closer together
Erodes material
What is the fetch?
The distance the wind has blown over uninterrupted
What are 4 types of erosion
Hydraulic action
Attrition (against each other)
Abrasion (against cliff)
Solution
Explain and name 4 types of transportation
Traction - large pebbles rolling on sand
Saltation - hopping or bouncing motion of particles too heavy to be suspended
Suspension - particles suspended in water
Solution - dissolved chemicals
Name and explain the 3 types of weathering
Mechanical - break up of rocks into smaller particles
Biological - plant roots grown in rocks or animals burrowing in weak rocks
Chemical - rainwater slowly dissolves certain types of rock + materials
Describe long short drift
Waves approach beach at the same angle as the prevailing wind
The swash carries material up the beach
The back swash drags material straight back down the beach due to gravity
This results in a zig zag route
Name the 4 types of mass movement
Rockfall
Rotational slip
Landslides
Mudflow
Describe how headlands and bays are formed
- rock is discordant to cliff
- soft rock is faster to erode and hard rock is slower to erode
- hydraulic action and abrasion erode soft rock into a bay as cliff retreats
- hard rock sticks out of the cliff forming a headland
Describe the formation of caves, arches, stacks and stumps
- headland has lines of weaknesses that are eroded away by hydraulic action and abrasion
- this erodes into a cave and then into an arch
- arch collapsed due to weathering and a stack is formed
- stack is worn down by weathering
- stack collapses and becomes a stump
Describe how wave cut notches and wave cut platforms are formed
- abrasion and hydraulic action erode base of cliff, creating a wave cut notch
- this is eroded further and the top of the cliff becomes heavy and collapses
- material is washed away to sea and process repeats
- in the process, a wave cut platform is formed
Explain how sand dunes are formed?
- sand piles up around an embryo dune
- marram grass grows and more sand piles on top, binding sand together forming fore and yellow dunes
- marram grass starts nutrient cycle, allowing more plants to grow
- wind forms depressions in sand, causing dune slacks which can turn into ponds
- rotting vegetation forms grey dunes and very early soils
This continues and a mature dune is formed
What are the conditions needed for a dune to form?
- long tidal range to let sand dry
- large supply of sand
- wide, flat beach
- prevailing wind
- obstacle
What features to sandy and shingle beaches have?
Sandy
- wide, flat beaches
- waves loose energy when spreading out on bay
- constructive waves deposit sediment on beach
- bags
Shingle
- narrow and steep
- destructive waves erode the cliff
- or constructive waves deposit large pebbles and finer sediment washes away
How are spits formed?
- Formed on a sharp bend in cliff
- longshore drift transports sediment into sea
- strong waves and winds curve the end of split causing a recurved end
- sheltered area means sediment piles up in spit
- plants grow there and a salt marsh is formed
How are bars formed?
Bars used to be spits but they have reaches the other side of the cliff
Joins two headlands together, forming a lagoon
What are groynes and what are the adv and disadv
Trap sediment from transportation of longshore drift
+ cheap to maintain
+ wider beaches popular to tourists
- increased erosion elsewhere
- unattractive
What is rock armour and + and -
Large sea wall absorbs impact of waves
+ effective
+ has walkway
- unnatural
- Expensive and high maintenance
What is rock armour and + and -
Large boulders that break and absorb wave erosive energy
+ cheap
+ often used for fishing
- usually imported rocks
- expensive to transport
- obtrusive
What are gabions and + and -
Absorbs erosive power
+ Cheap
+ vegetates overtime
+ improved drainage
- for a while, looks unattractive
- cages rust
