Coastal landscapes in the UK Flashcards
How do waves form
By wind blowing over the sea
Friction with the surface of the water causes ripples that develop into waves
Features of a constructive wave
Formed by storms hundreds of kilometres away - common in summer
low waves with crests far apart
gently sloping wave front
push sand and pebbles up the beach
deposit material
Features of a destructive wave
Formed by local storms close to the coat - common in winter
Waves are close together
High waves and steep wave front
Breaking waves plunge onto beach with little forward swash
Strong backwash erodes material
What is mechanical weathering and an example
The breakdown of rock without changing its chemical composition
eg freeze thaw weathering
(expansion and thawing of ice repetitively in rock)
What is chemical weathering and an example
The breakdown of rock by changing the chemical composition
e.g Carbonation (acid rain dissolving alkaline rocks such as limestone)
What is biological weathering and an example
Caused by the actions by flora and fauna
e.g plants growing in cracks in rocks or animals borrowing into weak rock
What is mass movement
The downward movement of weathered material under the influence of gravity
What are the types of mass movement
Rockfall - rock breaks away often due to freeze fall on a steep cliff face
Landslide - blocks of rock slide downhill
Mudflow - saturated soil and weak rock flow downhill
Rotational slip - slump of saturated soil and weak rock along a curved surface
Types of coastal erosion
Solution - dissolving of soluble chemicals in rock
Corrasion - rock fragments picked up by the sea are thrown at the cliff and scrape away the rock
Abrasion - The ‘sandpapering’ effect where
Attrition - rock fragments carried by the sea knock against each other becoming more rounded
Hydraulic power - the water is forced into cracks in the cliff and eventually break it up
How is sediment transported
Solution - dissolved chemicals
Suspension - particles carried in the water
Traction - large pebbles rolled along the seabed
Saltation - a hopping or bouncing motion of particles to heavy to be suspended
What is deposition and why does it happen
Deposited sediment and occurs when waves lose their energy
What is a discordant coastline
Vertical bands parallel to the direction of waves
What is a concordant coastline
Horizontal bands of rock perpendicular to the direction of waves
What kind of coastlines are headlands and bays formed on
Discordant
How do stacks form
Hydraulic power erodes the rock
Cave forms
Repeated erosion deepens the cave until it breaks through the headland to form an arch - eg. Durdle Door
Erosion continues to wear away at the arch until it eventually collapses
Forms a stack - e.g Old Harry in Dorset
How do cliffs erode
Erosion creates a wave cut notch
This then collapses
The cliff retreats
A new wave cut notch is formed
What are sand beaches
Created by low energy waves
Flat and wide
Long gentle slope
What are shingle beaches
Created by high energy waves
Steep and narrow
Steep slope
How is a spit formed
LSD deposits material past a bend
The area behind can become a salt marsh
How is a bar formed
When a spit joins 2 headlands together
Lagoon formed behind
How are sand dunes formed
When LSD deposits material up the beach by wind
Obstacles decrease wind speed so sand is deposited
Colonised by plants - eg. marram grass - this stabilises the sand and allows foredunes and mature dunes to form
What is the Dorset coast made of
Bands of hard and soft rock
eg. Chalk and clay
Where is Old Harry
Swanage Bay
Types of hard engineering for coastal areas
Sea Wall - physical wall that reflects waves back out to sea
Gabions - wall of wire cages filled with rocks
Rock Armour - boulders that are piled up on the coast to dissipate some wave energy
Groynes - traps sediment transported by LSD
Types of soft engineering for coastal areas
Beach nourishment - adding sand from elsewhere
Beach reprofiling - moving sand around
Dune regeneration - planting vegetation and more sand
What is the term for doing nothing to coastal areas
Managed retreat
e.g in Lincolnshire to protect 400 k homes from floods and attract more species of birds and wildlife
Why does Lyme Regis need protecting from erosion
Much of the Eastern side of the town is built along the edge of cliffs
3600 population and 50 k tourists each year
Local economy depends on tourism
1km of coast already has hard engineering strategies
Current defences in Lyme Regis
4 phase plan began in 1990 and finished in 2015
£19.5 million
390m of sea walls and rock armour
Pros and cons of the current defences in Lyme Regis
Pros:
Increase trade by 20%
People feel more secure in Lyme Regis
Cons:
More traffic and pollution because of tourism
Expensive for a ‘shorter term’ solution
