Y13 MB - Coastal Landscapes

Question 1

What is a coastal landform?

Answer 1

Individual components of a coastal landscape e.g cliffs, beaches, arches

Question 2

What processes are involved with the formation of a landform?

Answer 2

Erosion
Weathering
Deposition
Wave refraction
Sea level change

Question 3

What is a discordant coastline?

Answer 3

Where the alternating bands of different rock types are perpendicular to the coastline

Question 4

What is a concordant coastline?

Answer 4

Where the alternating bands of different rock are parallel to the coastline

Question 5

On which kind of coastline do headlands and bays form?

Answer 5

Discordant coastline

Question 6

How is a wave-cut platform formed?

Answer 6

Where destructive waves break at the foot of a cliff their energy is concentrated
Erosion (hydraulic action and corrosion) is concentrated at the high tide line and the cliff becomes undercut with a wave-cit notch
The cliff above is weathering and put under stress, over time it cannot be supported so collapses
The scree at the base of the cliff is transported away by the waves
Over time the waves break further out to sea so have to travel over more platform to reach the base of the cliff (wave energy has dissipated before it reaches it)
A platform forms which is fairly smooth and has a gentle slope

Question 7

What does the formation of a wave-cut platform involve? (Short)

Answer 7

Formation of a wave-cut notch
Cliff retreat

Question 8

How is the formation of a wave-cut platform a negative feedback mechanism?

Answer 8

Due to cliff retreat, the waves break further out to sea and have to travel over more of the wave-cit platform to reach the bas of the cliff
So the wave energy dissipates by the time it reaches the base of the cliff
There is therefore a slower rate of erosion

Question 9

How is a headland and bay formed?

Answer 9

On a discordant coastline with alternating bands of resistant and les resistant rock perpendicular to the coastline
When erosion occurs e.g from hydraulic action, corrosion and wave pounding the less resistant rock is eroded and so retreats faster
This means the resistant rock protrudes out to sea as headlands

When waves move towards the shore they are refracted due to reaching shallower water near the headland and slowing down, dissipating their wave energy
Therefore, when they move inwards towards the less resistant rock they have less energy so deposit their material
Over time, this deposition of sediment builds up and a bay is formed

Question 10

How is a stump formed? (And other landforms within that)

Answer 10

Takes place on a headland
There is a weakness in the headland due to a joint between in the rocks or a fault
This over time is widened by erosion such as hydraulic action and abrasion
Over time further erosion means that this widens and forms a cave
Where caves are eroded on either side of a headland they may break through to form an arch
The roof of the arch is weathered by sub-aerial processes such as biological weathering or chemical weathering from the salt-spray
The roof becomes unsupported and collapses to leave a stack further out to sea than the headland
The stacks base in the intertidal zone is subject to erosion from the waves so when a wave-cut notch is formed the rock above cannot be supported so it collapses
This leaves a stump

Question 11

What landforms are involved in the formation of a stump?

Answer 11

Crack
Cave
Arch
Stack
Stump

Question 12

What is a blowhole?

Answer 12

Where a cave faces the oncoming waves
The full force of the waves is applied to the back of the cave (wave energy concentrated)
This can enlarge cracks in the cave roof
Combined with weathering of the land above, the overlying rocks can collapse over time
This forms a blowhole in the rock

Question 13

Where can the cliff profile features of an arch, stack and stump be found?

Answer 13

Old Harry’s Rocks, Dorset

Question 14

In what area restrictions do beaches form?

Answer 14

Lowest tide line and highest point reached by storm waves

Question 15

Why are shingle beaches steeper than sand beaches?

Answer 15

Shingle beaches have larger pieces of sediment which cannot be easily compacted by the waves
As the backwash can percolate through the shingle rocks and a lot of energy is required to transport them away from the beach, it is unlikely to be eroded

Question 16

What is a berm?

Answer 16

Series of high tide lines and ridges formed by constructive waves
At the back of the beach where powerful swashes deposit materials during high spring tides

Question 17

What is a cusp?

Answer 17

Where the waves break directly onto the beach where both swash and backwash are strong
They generally form at the junction where the sand in the lower part of the beach meets the shingle on the upper part of the beach
The curved sides channel incoming swash onto the centre of the cusp which creates strong backwash, removing sediment which further deepen the cusp

Question 18

What are ripples?

Answer 18

Action of the tides moving back and forth across the sand from ripples

Question 19

What are ridges and runnels

Answer 19

Ridges form where backwash deposits sediment they run parallel to the coastline
Runnels break up ripples and are where water runs through to return back to the sea

Question 20

What is the difference between a swash-aligned beach and a drift-aligned beach?

Answer 20

Swash-aligned beaches form in low energy environments such as a bay where waves are moving parallel to the shore
Wave refraction in the bay may cause a bay-head beach to form

Drift-aligned beaches form where waves approach the coast at an angle
Longshore drift moves sediment along the beach

Question 21

What is a simple spit?

Answer 21

Straight or recurved spits with no minor spits or recurved ridges along their landward side

E.g Spurn Head, Humberside

Question 22

What is a compound spit?

Answer 22

Have a series of minor spits or recurved ridges along their lanyard sides

E.g Hearst Castle Spit, Hampshire

Question 23

What is a spit?

Answer 23

Long, narrow ridges of deposited sediment which are joined to the mainland at one end stick out to sea or across an estuary / bay

Question 24

How does a spit form?

Answer 24

They form where material is moved along the coast by longshore drift but where the coastline changes direction due to an estuary or river mouth
Where there are opposing currents and sheltered conditions, sediment is deposited which over time begins to form a spit due to longshore drift
During storms larger pieces of material are deposited which make the spit more permanent as it is harder to be removed by erosion

Question 25

Why may the end of a spit become recurved?

Answer 25

Wave refraction and secondary winds mean that sediment is deposited around the end of the spit
If this happens a number of times a compound spit is formed

Question 26

Why may the growth of a spit stop?

Answer 26

A river flowing out to sea prevents the spit from growing across an estuary

Question 27

How may a spit cause a salt marsh to form?

Answer 27

When the spit grows across the estuary, it shelters it so fine sediment is deposited there (especially due to the opposing tidal and river currents)
This is further stabilised by the growth of salt-tolerant plants
Submerged at high tide and exposed at low tide

Question 28

What is a tombolo?

Answer 28

An island connected to the mainland by a mound or ridge of sediment
Sometimes called ‘tied islands’

E.g the Angel Road tombolo in Japan

Question 29

How does a tombolo form?

Answer 29

As waves move towards a coastline, they slow down as they reach shallower water and are refracted
They first reach the islands close to the coast as they are further out to sea
As the waves are moving at a slower pace, they move around the island instead of over it
This means that their energy dissipates so when they meet at the other side of the island sediment is deposited
This sediment continues to build up until it creates a sandbar that connects the island to the beach

Another way is by longshore drift

Question 30

What is a barrier beach?

Answer 30

Where a spit extends across a bay or joins two headlands together

Slapton Ley in the UK

Question 31

How does a barrier beach form?

Answer 31

Gravel deposited by the English Channel when glaciers melted after the last ice age, by constructive waves
Longshore drift has added more material to them

Behind the barrier beach, a lagoon is produced. Over time the lagoons may become full of sediment so eventually dry up

Question 32

When can barrier beaches not form?

Answer 32

When there is current flowing off the land

Question 33

What is an offshore bar? And how is it formed?

Answer 33

A regional where sand is deposited when waves down have enough energy to transport the load of material to the shore
When waves break early so immediately drop material
Could also be formed as a result of backwash from destructive waves, removing sediment from the beach

Question 34

How can an offshore bar help protect the beach?

Answer 34

It absorbs wave energy which reduces the rate of erosion of the beach / cliff base

Question 35

In the formation of sand dunes, how is sand transported up the beach?

Answer 35

Onshore winds pick up and drop the sand so it moves up the beach by saltation

Question 36

Does a high tidal range mean sand dunes are more or less likely?

Answer 36

More likely for sand dunes to develop
A larger tidal range means there there will be large expanses of exposed sand that can dry out at low tide so dunes can form

Question 37

Describe how sand dunes are formed

Answer 37

Sand moves up the beach by saltation and is initially trapped by obstacles (often on the storm berm where driftwood is present)
As sand becomes trapped, the obstacle grows which slows the wind and leads to further deposition
Embryo dunes form which may become colonised by pioneer species (plant roots stabilise dune)
When the dunes grow and become out of reach of high tide they are yellow dunes
As more sand accumulates and plants grow, adding organic matter, they become fixed grey dunes
Dune slacks can form between dunes where the water table is at the surface
Over time mature dunes form where hardy trees grow
Final stage of succession is climax vegetation

Question 38

Give examples of the pioneer species which colonise embryo dunes

Answer 38

Marram grass
Sea couch

Question 39

How high are embryo dunes and how colonised are they?

Answer 39

They are only 1m high
Around 80% exposed sand

Question 40

How high are yellow dunes and how colonised are they?

Answer 40

5m high
20% exposed sand

Question 41

Describe the characteristics of grey dunes and why they are called this

Answer 41

Grey dunes are 8-10m high
Less than 10% exposed sand (plants such as gorse bushes)

Called grey dunes as with high colonisation if vegetation, more organic matter is added to the dune and the humus increases

Question 42

What kind of plants colonise the mature dunes?

Answer 42

Hardy vegetation such as birch trees, heather and gorse bushes

Question 43

What is the process of succession on sand dunes called?

Answer 43

Psammosere

Question 44

As you move further inland from the shore, what happens to the sand dunes)

Answer 44

Colonisation increases / exposed sand decreases
Water content increases
Humus (organic material content) increases
pH decreases

Question 45

Give an example of sand dunes in the Uk

Answer 45

Studland Bay on the Dorset Coast

Question 46

How is a mudflat formed?

Answer 46

Occurs in low energy environments such as in an estuary or behind a spit
Slow flowing water from the river mouth which is carrying a lot of suspended fine sediment meets saline sea water
Flocculations occurs where clay particles aggregate and join together
This makes the particles much larger and heavier so they sink to the bottom of the estuary
The mudflat is formed and is submerged at high tide and exposed at low tide

Question 47

How are salt marshes formed from mudflats?

Answer 47

Pioneer species begin to colonise the mud flat which are halophytic (salt-tolerant) such as Spartina
They bind the mud together as well as slowing currents down as they flow over the mudflat - causing more deposition
As these plants due and decompose, the surface of the marsh increases
Therefore the mudflat is submerged for shorter periods of time and it becomes a salt marsh
More complex flowering species can colonise the salt marsh such as sea lavender as they are less salt-tolerant
More deposition occurs and the vegetation becomes more dense, increasing the level of the surface
When the marsh rises above the level of the spring high tides trees and shrubs can begin to grow and over time climax vegetation is reached

Question 48

What is succession on mudflats and salt marshes called?

Answer 48

Halosere

Question 49

Give an example of mudflats and salt marshes in the Uk

Answer 49

Morecambe Bay in Lancashire

Question 50

What is a barrier island?

Answer 50

Where barrier beaches become separated from the mainland
Made up of either sand or shingle and are very long (up to 100 miles), narrow and becomes vegetated as they get older and vegetation succession occurs

E.g the West Frisian Islands in the Netherlands

Question 51

How is it thought that barrier island are formed?

Answer 51

Out of sediment originally deposited when glaciers melted 18,000 years ago at the end of the last Ice Age
It is probable that currents that deposited this material into barrier beaches caused sea level rise so the beaches became separated from the mainland