Physical: Coastal Landscapes and Landforms

Question 1

What factors affect the coastal landscape?

Answer 1

Coastal geology and lithology,
Climate,
Nature of tides and waves.

Question 2

What are the different classifications of coastlines?

Answer 2

Concordant or discordant,
Cliffed coast, flat coast or graded shoreline,
Emergent or submergent.

Question 3

How are headlands and bays formed on discordant coastlines?

Answer 3

On discordant coastlines, the softer, less resistant rock is eroded more easily by processes such as hydraulic action, abrasion and solution, than the harder rock. This is called differential erosion. This causes the land with softer rock to retreat, forming a bay and the land with harder rock to stay protruding out, forming a headland. Similarly, the process of wave refraction causes higher rates of deposition in the bay. This is because waves bend towards the headland, concentrating wave energy in that area.

Question 4

What affects the erosion of rocks of the same type?

Answer 4

The angle dip of strata,
Faults,
Joints and bedding planes.

Question 5

How are headlands and bays formed on concordant coastlines?

Answer 5

On a concordant coastline, the rock structure like faults, joints and bedding planes in the rock affect the rate of erosion. If there are more faults, joints and bedding planes, the rock has more areas of weakness, due to increased water access and is therefore more susceptible to erosion and weathering. For example, there is increases susceptibility to freeze thaw weathering which involves water getting into cracks and when it freezes, the water expands, creating larger cracks in the rock. Similarly, the nature of the waves as well as the direction of prevailing wind on a coastline also affect which parts are eroded first, forming bays, or are less vulnerable to erosion, forming headlands.

Question 6

How are wave-cut platfroms formed?

Answer 6

At the base of a cliff, wave energy is concentrated between the high and low water mark. Through processes of erosion (hydraulic action and abrasion) a wave-cut notch may be formed. As the process of erosion continues, the wave-cut notch is further eroded until the cliff is undercut. Eventually, the cliff will fall due to gravity, and this further increases erosion due to more sediment available for abrasion. After successive collapses, the cliff line begins to retreat and a gently sloping wave-cut platform will be formed. The process of erosional undercutting will continue creating a much longer wave-cut platform. As this occurs, the waves travel over the platform for longer to reach the cliff, and therefore will lose a lot of energy before reaching the base of the cliff, resulting in weaker waves and less erosion on the cliff. This causes the cliffs to stop retreating and is why wave-cut platforms are usually no longer than 500m.

Question 7

Which processes affect a crack in a headland?

Answer 7

Erosion:
Hydraulic action.

Question 8

Which processes affect a small cave?

Answer 8

Erosion:
Hydraulic action,
Solution (dependant on rock type).

Question 9

Which processes affect a larger cave?

Answer 9

Erosion:
Hydraulic action,
Abrasion.

Question 10

Which processes affect an arch?

Answer 10

Erosion:
Hydraulic action,
Abrasion,
Solution

Question 11

Which processes affect the gap between the end of a headland and a stack?

Answer 11

Erosion:
Hydraulic action,
Abrasion,
Solution.
Weathering:
Chemical (E.g. Carbonation, Oxidation and Solution.)
Biological.

Question 12

Which processes affect a stack?

Answer 12

Erosion:
Hydraulic action,
Abrasion,
Solution.
Weathering:
Biological,
Chemical,
Physical.

Question 13

Which processes affect a stump?

Answer 13

Erosion:
Hydraulic action,
Abrasion,
Solution.
Weathering:
Chemical,
Biological

Question 14

What is an example of caves, arches, stacks and stumps?

Answer 14

Old Harry Rocks, Dorset.

Question 15

What is a beach?

Answer 15

Beaches are the accumulation of sediment between the low spring tides and the highest point reached by storm waves.

Question 16

How does sediment size and shape affect beach profiles?

Answer 16

Fine, smooth sediment will create a gently sloping beach as it has a lower angle of rest so will roll down the beach, creating a gentle gradient. Also, fine particles will pack tightly together when wet and allow very little percolation making most swash return as backwash so material is transported down the beach.
Coarse sediment will create a much steeper beach as water can percolate through the gaps between the shingle so backwash is limited in it’s ability to transport material down the beach. Also, the angluar shape means they do not roll as easily down the beach.

Question 17

What is a storm beach?

Answer 17

A ridge of the biggest boulders thrown by the largest waves above the HWM. A series of berms will be formed as the high tide line changes.

Question 18

What is a swash-aligned beach?

Answer 18

Generally oriented parallel to the incoming wave crest. Experience minimal longshore drift and are found on irregular coastlines where waves hit sections of the coast head-on.

Question 19

What is a drift-aligned beach?

Answer 19

Generally oriented parallel to the direction of dominant longshore drift and often have large amounts of sediment transported along them by longshore drift. Regular section of coastline and can extend out (spit).