Section C - Coastal Landscapes In The UK Flashcards
What are constructive waves? Give a few characteristics of these waves
These are low waves that surge up the beach and spill with a powerful swash. They carry and deposit large amounts of sand and pebbles and construct the beach, making it more extensive
What are destructive waves? Give a few characteristics of these waves
These are formed by local storms close to the coast and they can destroy the beach. They are closely spaced and often interfere with each other
What is the fetch
When friction with the sea surface creates waves. The longer the fetch the more powerful the waves
What are waves
Bulges of water moving in a cyclical motion. Waves come into contact with the sea bed
What are the 5 steps of waves approaching the coast
1) circular orbit in open water
2) friction with the sea bed distorts the circular orbital motion
3) increasingly elliptical orbit, top of wave moves faster
4) wave begins to break
5) water from previous wave returns, water rushes up the beach
What happens at beachy head, 2001 at rockfall
During the wet winter of 2000, the chalk rock became saturated with water. The water froze during the winter. In April 2001, this caused a rockfall.
What causes cliffs to collapse
Cliffs collapse because of different types of weathering. This is the weakening or decay of rocks in their original place on, or close to the ground surface. it is mostly caused by weather
What is mechanical weathering (physical)
the distintegration (break up) of rocks. where this happens piles of rock fragments called SCREE can be found at the foot of cliffs
what is chemical weathering caused by
caused by chemical changes - rainwater, which is slightly acidic, very slowly dissolves certain types of rocks and minerals
what is biological weathering caused by
caused by the actions of flora and fauna. plant roots grow in cracks in the rocks. animals such as rabbits, burrow into weak rocks such as sands
how does freeze thaw weathering happen (mechanical)
1) water collects in cracks or holes (pores) in the rock
2) at night this water freezes and expands and makes cracks in the rock bigger
3) when the temperature rises and the ice thaws, the water will seep deeper into the rock
4) after repeated freezing and thawing, fragments of rock may break off and fall to the foot of the cliff (SCREE)
how does salt weathering happen (mechanical)
1) sea water contains salt. whem the water evaporates it leaves behind salt crystals
2) in cracks and holes these salt crystals grow and expand
3) this puts pressure on the rocks and flakes may eventually break off
how does carbonation weathering happen (chemical)
1) rainwater absorbs C02 from the air and becomes slightly acidic
2) contact with alkaline rocks such as chalk and limestone produces a chemical reaction causing the rocks to slowly dissolve
what is mass movement
the downward movement or sliding of material under the influence of gravity
what happened in 1993 (mass movement)
60 metres of cliff slipped onto the beach near Scarbourough in North Yorkshire taking with it part of the Holbeck Hall Hotel
what is rockfall
when fragments of rock break away from the cliff face, often due to freeze thaw weathering
what is a landslide
when blocks of rock slide downhill
what is mudflow
when saturated soil and weak rock flows down a slope
what is rotational slip
slump of saturated soil and weak rock along a curved surface
what does coastal erosion involve
the removal of material and the shaping of landforms
what is the process of solution
EROSION
the dissolving of soluble chemicals in rocks e.g. limestone
what is the process of corrasion
EROSION
fragments of rock are picked up and hurled by the sea at a cliff
what is the process of abrasion
EROSION
the sandpapering effect of pebble grinding over a rocky platform, often causing it to become smooth
what is the process of hydraulic power
EROSION
the power of the waves as they smash onto a cliff
what is the process of attrition
EROSION
rock fragments carried by the sea knock against one another causing them to become smaller and more rounded
what is solution
TRANSPORTATION
dissolved chemicals ofter derived from limestone or chalk
what is suspension
TRANSPORTATION
particles carried (suspended) within the water
what is traction
TRANSPORTATION
large pebbles rolled along the seabed
what is saltation
TRANSPORTATION
a hopping or bouncing motion if particles too heavy to be suspended
what is the process of longshore drift
1) waves approach the coast at an angle
2) the waves swash sediment onto the beach
3) gravity pulls backwash back, to see at a right angle to the coast
4) the process repeats
what kind of coastal landforms is longshore drift responsible for
beaches and spits
how does coastal depostition happen
waves lose energy in sheltered bays, and where water is protected by spits and bars. here sediment can no longer be carried or moved and is therefore deposited. this explains why beaches are formed bays
what is often found in sheltered estuaries, behind spits, where there is little flow of water
mudflats and saltmarshes
what is a concordant coastline
a coastline where there is only one rock type e.g. southern coast of the Purbeck Isle
what is a discordant coastline
where multiple rock types form in bands heading inland from the coastline e.g. Eastern Coast of the Purbeck Isle
EROSION LANDFORMS : what can’t you see caves and arches on a map
because of the rock above them
EROSION LANDFORMS: what do stacks look like on a map
little blobs in the sea
EROSION LANDFORMS: what do cliffs (and other steep slopes) look like on a map
little black lines
EROSION LANDFORMS: what do wave cut platforms look like on a map
bumpy edges along the coastline
DEPOSITION LANDFORMS: what do sand beaches look like on a map
pale yellow
DEPOSITION LANDFORMS: what do shingle beaches look like on a map
white or yellow with speckles
DEPOSITION LANDFORMS: what do spits look like on a map
a beach that carries out to sea but is attached to the land at one end. there might also be a sharp bend in the coast that caused it to form
what is hard engineering
using artificial structures such as sea walls to control the coasts natural processes
how is soft engineering different to hard engineering
less intrusive and more environmentally friendly with methods to protect the coast
what is managed retreat
when the coastline is deliberately allowed to flood or erode
how is managed retreat economically and environmentally friendly
economically: because its relatively cheap
environmentally: because it forms new habitats e.g. salt marsh
Hard engineering - what are groynes
groynes are timber or rock structures built out to sea from the coast. they trap sediment being moved by longshore drift and enlarge the beach. the wider beach acts as a buffer to reduce wave damage
what are some advantages of groynes
> create a wider beach which can be popular with tourists
provide useful structures for people interested in fishing
not too expensive-£150,000 each
what are some disadvantages of groynes
> they starve beaches further along the coast leading to increased rates of erosion
they’re unnatural and unattractive
Hard engineering - what are sea walls
sea walls are concrete or rock barrier against the sea, places at the foot of cliffs or at the top of a beach. has a curved face to reflect the waves back into the sea
what are some advantages of sea walls
> effective at stopping the sea
>often has a walkway for people to walk along
what are some disadvantages of sea walls
> can look unnatural
expensive (£5,000-£10,000 per metre)
high maintanence
Hard engineering - what is rock armour
piles of large boulders dumped at the foot of a cliff. the rocks force waves to break, absorbing their energy and protecting the cliffs
what are some advantages of rock armour
> relatively cheap (£200,000 per metre)
easy to maintain
often used for fishing
what are some disadvantages of rock armour
> expensive to transport
don’t fit in with the local geology
can be obtrusive
hard engineering - what are gabions
wire cages filled with rocks that can be built up to support a cliff or provide a buffer against the sea
what are some advantages of gabions
> cheap to produce (£50,000 per 100m)
>can improve drainage of cliffs
what are some disadvantages of gabions
> look unnatural
>cages only last 5-10 years before they rust
soft engineering - what is beach nourishment
the addition of sand or shingles to an existig beach to make it higher or wider. The sediment is usually obtained offshore locally so that it blends in with the existing beach material
what are some advantages of beach nourishment
> relatively cheap (500,000 per 100m)
easy to maintain
blends in with existing beach
what is a disadvantage of beach nourishment
> needs constant maintenance
soft engineering - what is dune regeneration
using sand dunes to effectively buff the sea. maram grass can be planted to stabilise dunes
what are some advantages of dune regeneration
> maintains a natural coastal environment that is popular with people and wildlife
relatively cheap (£200-£2000 per 100m)
what are some disadvantages of dune regeneration
> time consuming to plant grass and fence off areas
>can be damaged by storms
soft engineering - what is dune fencing
constructing fences on a sandy beach along the seaward face of existing dunes to encourage new dune formation. these new dunes help to protect the existing dunes
what are some advantages of dune fencing
> minimal impact on natural systems
>can control public access to protect other ecostystems
what are some disadvantges of dune fencing
> can be unsightly especially if fences become broken
>regular maintenance needed
what happened in Medmerry, Chichester, West sussex - managed retreat
> low sea wall in need of repair
£28 million spent compensating land owners
knocked 2 breaches in the sea wall, allowing the land to flood (2013)
slat marsh in natural barrier against coastal erosion and large storms
