4. Factors affecting coastal landscape

Question 1

Fetch

Answer 1

The Fetch is the distance over which the wind blows over the sea. The larger the fetch, the larger and more powerful the waves will be.
The fetch affects the energy that a wave has – the greater the fetch the greater the amount of energy that a wave has. This is because, over a large distance, the wind has had a greater amount of time to transfer energy to the wave.
Therefore, waves with the greatest energy are formed through a combination of a large fetch and a dominant wind blowing consistently in the same direction.

Question 2

Wave type

Answer 2

Constructive waves tend to occur during the summer when wind speeds are often lower. They contribute to the formation of things beach ridges and berms as material is moved up the beach due to the strong swash.
Destructive waves occur during storm conditions which are most common in winter. The plunging motion generates a powerful backwash that transports sediment down the beach face resulting in the net loss of sediment and increase in gradient.

Question 3

Wave refraction

Answer 3

Wave refraction is the bending of wave crests around headlands on irregular coastlines, causing an uneven distribution of wave energy.
Due to wave refraction, the headlands will receive a concentration of wave energy (because the orthogonals will converge around the headland) and so more erosion takes place.
This erosion often causes the formation of landforms such as caves, arches, stacks, and stumps.
However, in bays, the orthogonals diverge and so wave energy is dissipated and so deposition occurs

Question 4

Concordant coastline

Answer 4

A concordant coastline is where the alignment of the geology runs parallel to the coast.
This means that the rock is eroded at a similar rate and the outer rock layer provides a barrier to erosion of the rock further inland.
However, landforms such as bays can still be formed if the outer rock layer is punctured (e.g. through a fault-line), allowing the softer rock behind to be eroded.

Question 5

Discordant coastline

Answer 5

A discordant coastline is one where the alignment of the geology is perpendicular to the coast. This is the most common type of coastline in the UK.
Due to the different rock types, differential erosion occurs, leading to the formation of bays and headlands.

Question 6

Sub-aerial processes refer to the processes of weathering and mass movement.

Answer 6

Weathering is the breaking down of rock in situ. It can be divided into mechanical and chemical weathering. Mechanical weathering refers to physical processes like freeze-thaw action and biological weathering. Freeze-thaw weathering breaks up rock as water freezes in cracks. The ice applies pressure and breaks the rock. Biological weathering is caused by the roots of vegetation and nesting birds.

Question 7

Cliff profiles

Answer 7

The cliff profile will have a significant impact on the rates of erosion. Sedimentary rocks form as layers of deposited sediment, either on the beds of ancient oceans or rivers. Bedding planes layers of sediment that represent surfaces of exposure that occurred between depositional events. If the bedding planes are horizontal (A) then the cliff profile will be stable with a steep cliff face. However, due to tectonic movement, rock is uplifted and folded. This can change the alignment of strata in cliff profiles. Rock that has been lifted with its bedding planes tilted downwards away from the coast (D) create very stable cliff profiles. Rates of erosion will be slow as the cliff is supported by deeper running strata. Conversely, bedding planes that tilt upwards (C) have a cliff profile similar to the angle of tilt. This is due to the frequent mass movements that occur when the base of the cliff is eroded by wave action.

Question 8

Flanborough head

Answer 8

Flamborough Head is a promontory on the Yorkshire coast. It extends the land by 10km due to it being chalk and so having greater resistance to erosion than the boulder clay of the surrounding area
It is composed of chalk cliffs which stand 400 ft. high
It is an example of a headland on a discordant coastline as the surrounding areas are composed of less resistant rock and so have been eroded quicker.
The headland is home to many other coastal landforms (e.g. coves, sea caves, arches and stacks).
Although Flamborough Head seems to just be a single headland, it also contains a number of individual headlands and bays within it due to variations in the thickness of the chalk and due to weaknesses in the rock such as joints or bedding planes.