Coasts

Question 1

How are waves formed?

Answer 1

Waves are formed when the wind blows against the sea. This causes ripples to form and then this turns into waves. The distance that the wind blows against the water is called the FETCH. Longer the FETCH the more powerful the wave.

Question 2

What is a constructive wave?

Answer 2

Are low waves that surge up the beach.
Have a powerful smash and a small backwash.
Carry and deposit large amounts of pebbles and rocks and build up the beach.
Formed by storms that are a long way away.

Question 3

What is a destructive wave?

Answer 3

Formed by local storms.
Destroy the beach.
High and steep before plunging down onto the beach.
Small stash, but powerful backwash.

Question 4

What is weathering?

Answer 4

The breaking down of rocks e.g cliffs in their original place.
Due to temperature change and rainfall.

Question 5

What is mechanical weathering?

Answer 5

Break up of rocks.

When this happens piles of rocks called SCREE can be found at the bottom of cliffs.

Question 6

What is chemical weathering?

Answer 6

Causes by chemical changes, e.g. slightly acidic rain could dissolve certain types of rocks.

Question 7

What is biological weathering?

Answer 7

Plant roots grow in cracks in the rocks, animals then burrow into the rocks. Weakens them.

Question 8

What is freeze thaw?

Answer 8

A type of mechanical weathering.
Water collects in cracks of rocks.
At night water freezes, expands and makes rocks bigger.
When temperature goes down water will seep into rocks.
After lots of freezing and thawing rocks fall and break off of cliff to form SCREE.

Question 9

What is salt weathering?

Answer 9

A type of mechanical weathering.
Sea water contains salt. When the water evaporates it leaves crystals.
Crystals get into cracks and holes and expand.
Puts pressure on the rocks and they break away.

Question 10

What is carbonation?

Answer 10

A type of chemical weathering.
Rain water absorbs co2 and becomes slightly acidic.
In contact with alkaline rocks e.g. chalk a chemical reaction takes place and rocks dissolve.

Question 11

What is rockfall?

Answer 11

A type of mass movement.

Fragments of rocks break away from cliff due to freeze thaw. Then fall down cliff face.

Question 12

What is a landslide?

Answer 12

Type of mass movement.

Blocks of rock slide downhill.

Question 13

What is mudflow?

Answer 13

Type of mass movement.

Saturated soil and weak rock slope downhill.

Question 14

What is rotational slip?

Answer 14

Slump of saturated soil and weak rock along a curved surface.

Question 15

What is mass movement?

Answer 15

The shifting of rocks and loose material down a slope, e.g. a cliff.
It happens when the force of gravity acting on a slope is greater than the force supporting it.
It causes coasts to retreat rapidly.

3 types:

1. Slides-material shifts in a straight line
2. Slumps- material shifts with rotation
3. Rockfalls-material breaks up and falls down a slope.

Question 16

What is hydraulic action?

Answer 16

Type of coastal erosion.
Waves crash against rocks and compress air into cracks. This puts pressure on the rock. If the compression is repeated it widens the cracks and makes bits of rocks break off.

Question 17

What is abrasion?

Answer 17

Type of erosion.

Eroded particles in the water scrape and rub against rocks, removing small pieces.

Question 18

What is attrition?

Answer 18

Type of erosion.
Eroded particles in the water smash against each other and break into smaller fragments. Their edges also get rounded as they rub together.

Question 19

What is solution?

Answer 19

Type of erosion.
Dissolved carbon dioxide makes sea water slightly acidic. The acid then reacts chemically with some rocks, e.g. chalk and limestone dissolving them.

Question 20

How does the geological structure of a coastline influence the formation of erosional landforms?

Answer 20

1. Hard rocks like limestone and chalk are more resistant, so it takes them longer to be eroded by physical processes.
2. Soft rocks like clay and sandstone are less resistant, and erode more quickly.
3. Joints and faults are cracks and weaknesses in the rock. Rocks with lots of these also erode faster.

Question 21

What is a discordant coastline?

Answer 21

A coastline that is made up of alternating bands of hard and soft rocks that are at right angles to the coast.

Question 22

What is a concordant coastline?

Answer 22

The alternating bands of hard and soft rock are parallel to the coast.

Question 23

Are bays and headlands found on concordant or discordant coastlines and why?

Answer 23

Discordant because the bands of rocks are being eroded at different rates.
Concordant coastlines are being eroded at the same rate along the coast so this means fewer erosional landforms.

Question 24

How does the UK’s climate have an impact on coastal erosion and retreat?

Answer 24

Differences in temperature in the uk has an impact along the coast, e.g. mild temperatures increase the rate of salt weathering because water evaporates more quickly.
Storms in winter create high energy destructive waves which increases erosion on cliffs.
Intense rainfall can cause cliffs to become saturated with water and this makes mass movement more likely.

Question 25

Explain how waves erode cliffs to from wave cut platforms?

Answer 25

1. Waves cause most erosion at the bottom of a cliff. 2. This forms a wave-cut notch, which gets bigger as erosion continues. 3. Rock above the notch becomes unstable and eventually collapses. 4. The collapsed material falls away and then a new wave-cut notch begins to form. 5. Repeated collapsing causes the cliff to retreat. 6. A wave cut platform is what’s left behind as the cliff leaves.

Question 26

How doe headlands and bays form?

Answer 26

When there is an alternating band of resistant and less resistant rock along the coast. The less resistant rock e.g. clay erodes quickly and this forms a bay- bays have a gentle slope. The resistant rock e.g. chalk is eroded more slowly and its left jutting out to form a headland- headlands have steep sides.

Question 27

Explain how headlands are eroded to form caves, arches and stacks.

Answer 27

Headlands are normally made from resistant rocks that have weaknesses like cracks. Waves crash into the headlands and enlarge they cracks- hydraulic action and abrasion. This is repeated and the cracks enlarge making a cave. Continued erosion deepens the cave until it breaks through the headland- forming an arch. Erosion continues to wear away the rock supporting the arch, until it eventually collapses. This then forms a stack- separate from headland. Then erodes to form slump.

Question 28

What is longshore drift?

Answer 28

Material is transported along the coasts by longshore drift. Waves follow the direction of the wind. They usually hit the coast at an angle that isn’t a right angle. The swash carries material up the beach in the same direction as the wave. The backwash then carries material down the beach at right angles towards the sea. Over time, material zigzags along the coast.

Question 29

What is traction?

Answer 29

A transport process. | Large particles are pushed along the sea bed by the force of water.

Question 30

What is suspension?

Answer 30

Transport process. | Small particles like slit are carried along in the water.

Question 31

What is saltation?

Answer 31

Transport process. | Pebble size particles are bounced along the sea bed by the force of water.

Question 32

What is solution?

Answer 32

Transport process. | Soluble materials dissolve in the water and are carried along.

Question 33

What is deposition?

Answer 33

Is when material being carried by the seawater is dropped on the coast. It occurs when water carrying sediment slows down so that it isn’t moving fast enough to carry so much sediment. Coasts are built up when the amount of deposition is bigger than the amount of erosion. The amount of material that is deposited on an area of coast is increased when: 1. When there is lots of erosion else where so there is a lot of material 2. When there is a lot of transportation of material into that area. Low energy waves carry material to the coast but they are not strong enough to take a lot of material away. Lots of deposition and little erosion. Waves that preform this are called constructive waves.

Question 34

How are beaches formed by deposition?

Answer 34

Beaches are found on coasts between the high water mark(the highest point on the land the sea level gets to) and the low water mark. They are formed by constructive waves that deposit material like sand and shingle.

Question 35

What are the differences between sand and shingle beaches?

Answer 35

Sand- flat and wide,sand particles are small and the weak backwash can move them back down the beach creating a gentle slope. Shingle- steep and narrow, shingle particles are strong and the strong backwash can’t move them back down the beach. Build up and make a steep slope.

Question 36

What is a spit?

Answer 36

Spits form at sharp bends in the coastline, e.g. at a river mouth. Longshore drift transports sand and shingle past the bend and deposits it into the sea. Strong winds can curve the end of the spit. The sheltered area behind the spit is protected from waves and lots of material builds up there, plants can grow there. Over a period of time this sheltered area becomes a mud flat or salt marsh.

Question 37

What are bars?

Answer 37

A bar is formed when a spit joins two headlands together. The bar cuts of the bay between the headlands from the sea. This means a lagoon can form behind the bar.

Question 38

What are sand dunes?

Answer 38

Are formed when longshore drift deposits sand and the wind moves it up the beach. Obstacles can slow down the speed of the wind so sand is deposited. This sand is colonised by plants and the vegetation encourages it to grow, forming small dunes to form(embryo dunes). Over time the oldest dunes migrate inland as new smaller dunes are formed.

Question 39

Where is swanage?

Answer 39

A seaside town located in Dorset on the south coast of England. It is located in a sheltered bay that has a broad sandy beach. It is a discordant coastline.

Question 40

What is hard engineering?

Answer 40

Using artificial structures such as sea walls to control | natural processes.

Question 41

What is soft engineering?

Answer 41

More environmentally friendly methods that work with natural processes to protect the coast.

Question 42

What is managed retreat?

Answer 42

Enables the controlled retreat of the coastline, often allowing the sea to flood over low-lying land.

Question 43

What are groynes? | Advantages and disadvantages:

Answer 43

Timber or rock structures built out to sea from the coast. Trap sediment being moved by longshore drift and enlarge the beach. Ads- 1. Create wider beach, popular to tourists. 2. Not too expensive- £150000 per 200m Dis- 1. Groynes are unnatural and can be unattractive. 2. By interrupting longshore drift they starve beaches further along the coast.

Question 44

What are sea walls? | Ads and disads:

Answer 44

Concrete or rock barrier against the sea, placed at the foot of cliffs or at the top of a beach. Have a curved face to reflect waves back into the sea. Ads- 1. Effective at stopping the sea. 2. Often has a walkway or promenade to walk along. Dis- 1. Can look unnatural. 2. Very expensive and high maintenance £5000-10000 per metre

Question 45

What is rock armour? | Ads and Disads:

Answer 45

Piles of large boulders dumped at the foot of a cliff. Force waves to break, taking their energy and protecting the cliffs. Ads- relatively cheap and easy to maintain £200000 per 100m Often used for fishing and interest. Dis- can be expensive to transport. Rocks are usually from other coastlines or abroad. Do not fit in with the local geology.

Question 46

What are gabions? | Ads and Dis:

Answer 46

Wire cages filled with rocks that can be built up to support a cliff. Ads- cheap to produce £50000 per 100m Can improve drainage of cliffs. Will eventually merge into landscape and become vegetated. Dis- Look unattractive for a while. Only last 5-10 years before they rust.

Question 47

What is beach nourishment? | Ads and Dis:

Answer 47

Adding sand or shingle to an existing beach to make it higher or wider. The sediment is usually obtained locally so it blends in with the environment. Normally transported by a barge. Ads- cheap and easy to maintain £ 500000 per 100m Increases tourism by creating a bigger beach. Dis- Needs constant maintenance.

Question 48

What is dune regeneration? | Ads and Dis:

Answer 48

Marram grass is planted to stabilise dunes and help them develop. Fences can be used to protect them from being trampled. Ads- maintains a natural coastal environment that is popular with people and wildlife. Cheap £200-2000 per 100m Dis- Time consuming to plant the marram grass and fence areas off. Can be damaged by storms. People don’t always respond well to being fenced off form areas.

Question 49

What is dune fencing? | Ads and Dis:

Answer 49

Fences are constructed on a sandy beach along the seaward face of existing dunes to encourage new dune formation. These new dunes help protect old ones. Ads- minimal impact on natural systems. Can control public access to protect other ecosystems. Dis- can be unsightly if fences become broken. Maintenance needed regularly after storms.

Question 50

Why do coats need to be managed?

Answer 50

To maintain a balance between the forces of nature and the demands of people. People living near the coast need to be protected from erosion and flooding