Landforms

Question 1

What are beaches?

Answer 1

A depositional landform, beaches are accumulations of sediment and represent important temporary stores within a sediment cell.

Question 2

How are beaches formed?

Answer 2

Beaches form between the highest point reached by storm waves and the lowest spring tides.

Largely formed of sand and shingle, and the larger sediment tends to be at the top of the beach because it takes high energy storm waves to deposit this material.

Question 3

Outline sand beaches.

Answer 3

Sand beaches tend to be gentle in slope (less than 5*) because the sand grains are small and easily compacted which means that little water percolates through the sand therefore the majority of water that moves up the beach also returns through backwash so the beach is smooth and flattens the beach.

Question 4

Outline shingle beaches.

Answer 4

Shingle beaches are steeper (10 - 20*) because the larger sediment size means that it’s less easily compacted and therefore the waves, having broken, percolate back through the shingle.
Therefore the backwash doesn’t really transport material back down the beach. This creates a beach that’s unlikely to be eroded.

Question 5

What are storm berms?

Answer 5

At the top of a beach, a wider, flat area of sediment is deposited by a strong awash during spring high tides.

Question 6

What are berms?

Answer 6

In a beach, below a storm berm, there are a series of ridges which mark a series of high tide lines and are built by constructive waves.

Question 7

What are cusps?

Answer 7

Cusps form where the waves break directly onto the beach where both swash and backwash are strong and generally form at the junction where the sand on the lower part of the beach meet the shingle on the upper part of the beach.

The curved sides of the cusp channel incoming swash into the centre of the cusp which creates a stronger backwash flowing out of the centre of the cusp which further deepens the cusp.

Question 8

What are ripples?

Answer 8

They form in the sand dune due to the action of of the tide moving back and fourth across the sand.

Question 9

What are ridges?

Answer 9

At the LWM, ridges form where backwash deposits sediment. These run parallel to the coastline and are broken by runnels where water runs through to return to the sea

Question 10

What are the two types of beach?

Answer 10

Swash aligned and drift aligned.

Question 11

Outline swash aligned beaches.

Answer 11

• Waves arrive parallel to the shore, therefore swash and backwash occur.
• Experience minimal longshore drift

Question 12

Outline drift aligned beaches

Answer 12

• waves approach at an angle, therefore longshore drift occurs.
• can have considerable amounts of sediment transported long distances across them; often accumulating in the formation of a spit.

Question 13

What is the difference between landforms and landscapes?

Answer 13

Landforms are individual components of a landscape (e.g. cliffs, beaches, arches).

Whereas landscapes are made up of a number of landforms which give them their key characteristics.

Question 14

What is a good example of a negative feedback loop in landforms?

Answer 14

Wave cut platforms.

Question 15

Outline wave cut platforms as an example of a negative feedback loop.

Answer 15

Originally, the wave cut platform is fairly smooth and flat (sloping at less than 5*), and may be smoothed by further abrasion.

Over time, waves break further and further out to sea and have to travel over more and more platform before the cliff. This means that the wave energy is dissipated before it reaches the cliff.

Therefore, the rate of the cliff erosion decreases and the platform caresses to grow. So unlikely to grow wider than 500m.

Question 16

What is a spit?

Answer 16

A long, narrow ridge of deposited sediment which are joined to the mainland at one end and stick out into the sea or across the estuary or bay.

Question 17

What are the 2 types of spit?

Answer 17

Simple and compound

Question 18

What are simple spits?

Answer 18

Simple spits can either be straight or recurved but do not have minor spits or recurved spits along their landward edge.

Question 19

What are compound spits?

Answer 19

Compound spits have a series of minor spits or recurved ridges along their landward side which may show their former position.

Question 20

How do spits form?

Answer 20

Material is moved along the coast through longshore drift, but where the coast changes direction (often due to an estuary), sediment starts to build up in the sheltered lee of the headland which begins to form a spit.

During storms, larger sediment is deposited above the HWM, making the spit more permanent. Finer material continues to be moved along the spit through longshore drift and deeper into the estuary where energy is lost and the sediment is deposited which further extends the spit.

The end of the spit may become recurved as wave refraction and secondary winds and waves carry and deposit sediment round the end of the spit

Question 21

How does a compound spit form?

Answer 21

The end of the spit becomes recurved as wave refraction and secondary winds and waves carry and deposit sediment round the edge of the spit.

If it recurved enough, this is another change in coastline direction so the spit may continue to grow in its original direction. This may happen a number of times, forming a compound spit.

Question 22

How is a salt marsh formed?

Answer 22

A river which is flowing out to sea is likely to prevent a spit form growing right across an estuary, but very fine sediment may be deposited by the river in the ‘slack’ low energy zone behind the spit.

This forms a salt marsh which is an important coastal habitat and may be further stabilised by the growth of salt tolerant plants.

Question 23

What is a tombolo?

Answer 23

A beach that has formed between a small island and mainland.

Question 24

How is a tombolo formed?

Answer 24

Deposition occurs where waves lose their energy and so the tombolo begins to build up.

Question 25

Outline how a barrier island forms. (8 stages).

Answer 25

1. Vegetation (eg eelgrass) begins to grow on mudflats.
2. This slows down currents -> more deposition.
3. Next, pioneer species begin to colonise the area (called halophytes).
4. Deposition continues and plants continue to grow & die which raises the surface of the marsh. As this happens, the mudflats are submerged for shorter periods of time. So mudflat becomes salt marsh.
5. More complex flowering species (eg sea lavenders) become established as they are less tolerant of salt than pioneers.
6. More deposition occurs and vegetation becomes more dense which further raises the surface level. Soil conditions improve.
7. Where salt marsh rises Abi e level of spring high tide, trees start to grow.
8. Then reaches climax community.

Question 26

What is a barrier beach?

Answer 26

An elongated bank of deposited sand or shingle, lying parallel to the coastline and not submerged by incoming tides.

Question 27

What’s the difference between a barrier beach and barrier island?

Answer 27

A barrier beach is an elongated bank of deposited sand or shingle lying parallel to the coastline and not submerged by incoming tides.

A barrier island is where the bank is high enough to allow sand dunes to develop.

Question 28

How does a barrier island form?

Answer 28

1. Formed of sediment deposited by meltwater when glaciers melted at the end of the last Ice Age.
2. Currents deposited this material in barrier beaches. And the melting of ice meant that sea levels rose, leaving behind beaches which are separated from the mainland.
3. Subsequently, longshore drift has added more sediment.

Question 29

Describe the features of a barrier beach.

Answer 29

• made up of sand and shingle.
• long (up to 100 miles) and narrow.
• becomes vegetated as it gets older as vegetation succession occurs.
• usually found in areas with low tidal ranges and gently sloping offshore coastlines.

Question 30

Salt marshes are areas of flat, silty sediments that accumulate around estuaries.

What type of environment do they develop in?

Answer 30

• sheltered areas where deposition occurs (eg in the lee of a spit).
• where salt and fresh water meet.
• where there are no strong tides or currents to prevent deposition and accumulation.

Question 31

How are offshore bars formed?

Answer 31

Offshore bars are formed from sediment being deposited by coastal currents including longshore drift. But they remained submerged or semi submerged beyond the breaker zone.

Destructive waves erode sand from the beach with the strong backwash and deposit it offshore.

Offshore bars absorb the wave energy; thereby reducing the impacts of waves on the coastline.

Question 32

How do sand dunes form? (7)

Answer 32

1. Sand is trapped by obstacles (seaweed, rock, litter).
2. As sand is trapped, the obstacle grows, slowing the wind -> contributing to further deposition.
3. This becomes an EMBRYO DUNE and may be colonised by pioneer species (marram grass). The plant roots stabilise the dune and decaying plant matter adds organic content to the sand which aids water retention.
4. As the dunes grow, they become out of reach of high tide. And become YELLOW DUNES.
5. More sand accumulates, plants grow which adds organic matter to the dune so become fixed and form GREY DUNES as humus increases. They’re able to support larger plants which require more water.
6. DUNE SLACKS (depressions 😭) may form between the dunes where the water table is on the surface.
7. Inland from the grey dunes you find DUNE HEATH. This final stage in succession is the climax vegetation.

Question 33

Pneumonic of the sand dunes.

Answer 33

Even 
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