Coasts

Question 1

Coastal processes

Answer 1

Hydraulic action is when pounding waves compress trapped air in the rocks creating an explosive blast which weakens and loosens rock fragments

Abrasion is when rock fragments are thrown against the headland breaking down the cliff face, wearing away the rock

Solution is when carbonic salts in the seawater dissolves rock

Attrition is when rock fragments slowly being ground down by friction from wave action into smaller and rounder pieces which can then be used as an abrasive material.

Question 2

Wave cut platform

Answer 2

Explain 2/3 processes if 8/10 marks

Weaknesses such as joints, faults or cracks in cliffs are undercut by erosion to form a wave-cut notch (1)
The rock above overhangs over the notch and as erosion continues, the notch enlarges until the unsupported overhang collapses due to the weight (1)
The new cliff face is the eroded and through time, the cliff retreats inland, leaving a gently-sloping rocky surface called a wave cut platform, which extends out to sea away from the cliff (1)
The platform is abraded by rock materials, with rock pools and pot holes forming, evident and low tides(1)
An example of a wave-cut platform is Kimmeridge Bay in Dorset (1)

Question 3

Stack

Answer 3

Explain 2/3 processes

rocks contain weak points that are more easily eroded (1 mark)
* over time, lines of weakness are enlarged and develop into small sea caves (1 mark)
* in some cases, a blowhole can form in the roof of the cave (1 mark) as compressed air is pushed upwards by the power of the waves, causing vertical erosion (1 mark)
* there may be erosion on both sides of the headland (1 mark) due to wave refraction (1 mark) until eventually the sea cuts through the back walls of the caves, forming an arch (1 mark)
* continued erosion enlarges the arch (1 mark)
* the base of the arch is also undercut by the erosion, causing the arch to become unsupported (1 mark)
* eventually the arch collapses due gravity to form a stack (1 mark)
Old Harry is an example of a stack. (1 E mark)

Question 4

Headland Bay

Answer 4

Explain 2/3 processes

Headlands and bays result from coastlines that are formed of alternate sections of hard and soft rock.
The areas of soft rock are more easily and quickly eroded whereas the harder rock is more resistant to processes of weathering and erosion.
Where harder rock is present, headlands occur and where softer rock is being eroded, bays are formed.
The processes of erosion that take part in this can be hydraulic action, attrition and different types of weathering.
Constant attacking of the waves and material from the sea on the cliff face causes erosion of soft rock, leaving bits of land ‘jutting out’.

Question 5

Longshore Drift

Answer 5

Spits/ sandbars/ tombolo’s are formed by the process of longshore drift which is zig-zag movements of the waves (1)

Swash is where waves push material up the beach at an angle due to the prevailing wind (1)

The returning backwash is dragged back down the beach at right angles (1) due to gravity (1)

Question 6

Sandspits

Answer 6

(explain longshore drift for 4 marks)

Sand spits are formed through the process of longshore drift.
The swash is when waves driven by the prevailing winds push materials up the beach at an angle.
The returning backwash is dragged back by gravity down the beach at a right angle. A spit forms when there is a change in direction along a coast.
This allows a sheltered area for deposition. The material slowly builds up to appear above the water.
The spit develops as long as the supply of deposits is greater than the amount of erosion.
The shape can become hooked or curved at the end in response to changes in wind direction.

Question 7

Sandbars

Answer 7

(explain longshore drift for 4 marks)

Sand spits are formed through the process of longshore drift. The swash is when waves driven by the prevailing winds push materials up the beach at an angle. The returning backwash is dragged back by gravity down the beach at a right angle. Sandbars form when a sandspit stretches all the way across the mouth of a river or across a bay. This happens when there is no strong flow of water from a river into the sea. This encloses a sheltered lagoon behind it. An example of a sandbar is Slapton sands.

Question 8

Tombolos

Answer 8

(explain longshore drift for 4 marks)

Sandspits form when there is a change of direction on a coastline. (1)
This allows for a sheltered area for deposition (1) and material slowly builds up to appear above the water (1)
the spit develops as long as the supply of deposits is greater than the amount of erosion (1)
Tombolos form when a sandspit reaches an island (1)