section C:coasts Flashcards
describe constructive wave
these are low waves that search up the beach and spill with a powerful squash. They carry a deposit large amount of sand and pebbles and construct the beach making it more extensive. Surface tend to prefer constructive ways because they give long rides these waves are formed by storms often hundred kilometres away.
Describe destructive waves
These are formed by local storm close to the coast and they can destroy the beach hence their name. They are closely space and often interfere with each other producing a chaotic swirling mass of water. They’ve become high and steep before plunging down onto the beach, there is little forward motion and when a destructed wave breaks but a powerful backwash.
explain the three types of weathering
mechanical weathering – the disintegration of rocks. Where this happens powers of rock fragments called scream can be found at the foot of the cliff
Chemical weathering – caused by chemical changes way more that is slightly acidic
Biological weathering – due to flora and foreigner plant root grow in cracks
Explain freeze thaw
Water collects in cracks or holes in the rock
At night, this water freezes and expands and makes cracks in the rock bigger
When the temperature rises and the ice thaws,water will see deeper into the rock
After repeated freezing and thawing fragments of rock may break off and fall to the foot
Explain salt weathering
mechanic
Seawater contains salt when the water evaporate at leaves behind salt crystals
In cracks and holes these salt crystals grow and expand
This puts pressure on the rocks and flakes may eventually break off
explain carbonation
Chemical
Rainwater absorb CO2 from the air becomes slightly acidic
Contact with alkaline rocks such as chalk and limestone produces a chemical reaction causing the rock to slowly dissolve
what are the processes of mass movement?
Mass movement is the downward movement of material under the influence of gravity
Sliding
Slumping
Rock falls
what are three types of coastal erosion?
Hydraulic power, abrasion,attrition
explain longshore drift
Where waves approach head on, sediment is simply moved up and down the beach but if waves approach at an angle sediment will be moved along the beach in a zigzag pattern
how does coastal deposition happen?
Tate’s place in areas where the flow of water slows down. Waves lose energy in shelter space and wear water is predicted by spit or bars.
How are headlands and bays formed?
Our common coastal landforms are usually for when rocks different strength are exposed
how are spits formed?
Spits farm on coast where there is significant longshore drift
As it builds up, it starts to form an extension from the land
How are bars formed?
Longshore drift may cause a spectacle right across the bay trapping a freshwater lake behind it
explain sea wall
Concrete a rock barrier against the sea
Cost 5000 to 10,000 per meter
Advantages: effective at stopping the sea, often has a walkway or promenade for people to walk along
Disadvantages: can look obtrusive and unnatural, very expensive and high maintenance cost
explain groynes
timber or rock structure built out to see from the coast they trapped sediment being moved by longshore and enlarged the beach
Cost 150,000 each
Advantages: create a wider beach, useful structure for people interested in fishing, less expensive than some other methods
Disadvantages: interrupting long short if they start beaches further along the coast often leading to increase rates of erosion elsewhere
unnatural and rock groynes in particular can be viewed as unattractive 
explain rock armour
Powers of large boulders dumped at the foot of a cliff. The rocks force waves to break absorbing their energy and protecting the cliff.
Cost 200,000 per 100 meter
Advantages: relatively cheap and easy to maintain, provide interest to the coast, used for fishing
Disadvantages: from other parts of coastline or abroad, expensive to transport, often do not fit in with the local geology, can be obtrusive
Explain gabions
wire cage is filled with rock that can be built up to support a cliff or provide a buffer against the sea
cost up to 50,000 per 100 m
Advantages: cheap to produce and flexible in the final design, improve drainage of cliffs, eventually become vegetated and merge into the landscape
Disadvantage for while they look unattractive, only last 5 to 10 years before they rust
explain dune regeneration
Sand dunes are effective buffers to the sea but easily damaged and destroyed by trampling
cost 200 to 2000 per 100 m
Advantages: maintains a natural coastal environment that is popular with people and wildlife, relatively cheap
Disadvantages: time consuming to plant the mountain and grass and fence areas off, people don’t always respond well to being prohibited off access to planting areas, can be damaged by storms
Explain Dune fencing
Fences are constructed on a sandy beach along the seaward face of existing dunes to encourage new dunes, the new dunes helps protect the existing dunes
cost 400 to 2000 per 100 meter
Advantages: minimal impact on natural systems, can control public access to protect other ecosystems
Disadvantage: can be unsightly especially offences become broken, regular maintenance needed especially after storms
what is manage retreat?
Managed retreat is deliberate policy of allowing the sea to flood or road in area of relatively low value land
It is soft engineering as it allows natural processes to take place
