Costs - Exam Questions

Question 1

Describe three types of coastal erosion

Answer 1

Hydraulic action:
the weight and rorce of a wave crashing against a cliff removes particles of rocks from the cliff. It also includes the process where air Is trapped by a wave in a crack in the cliff and the enormous hydraulic pressure this creates opens up the crack further, which weakens the cliff

Abrasion (sometimes called corrasion):
boulders, pebbles shingle and sand are picked up by a wave and thrown against the cliff. This constant collision removes particles of rock from the cliff and wave-cut platform.

Solution (sometimes called corrosion):
some minerals (mainly the carbonate minerals found in rocks such as limestone and chalk) are dissolved by the weak acids found
in seawater.

Attrition:
this process does not actually erode the cliff
but it is the process that breaks up the boulders, pebbles,
shingle and sand on the beach. It takes place when the
rocks on the beach are rolled up and down the beach by
Swash and backwash. As this happens, they collide with
each other and become smaller and rounder as a result.

Question 2

Describe and explain the formation of a cave, arch and stack

Answer 2

These features form in narrow, rocky headlands. The sequence
starts when
1. a vertical crack, or fault, in the headland is eroded by hydraulic action, abrasion and solution to form a cave.

2. As the cave enlarges, it may erode all the way through a headland to form a natural arch.
3. Over time, the roof of the arch may be weakened and then collapse.This leaves an isolated pinnacle of rock, called a stack.

Question 3

Describe the conditions required for the development of coral reefs

Answer 3

The conditions that are required for the development of a coral reef are controlled by seven limiting factors.

1. Temperature: the mean annual temperature has to be over 18°C.The optimal temperatures for corals is between 23°C and 25°C.
2. Depth of water: coral reefs can only grow in depths of
   water less than 25 m.
3. Light: the shallow water allows access to light for tiny
   photosynthesising algae, called zooxanthellae. In return for
   the corals providing the algae with a place to live, these tiny
   algae provide the corals with up to 98% of their food.This is an example of a symbiotic relationship- an ecologcal relationship which benefits both sides.
4. Salinity: corals can only live in seawater, but they cannot
   tolerate seawater of high salinity
5. Sediment clogs up the feeding structures and
   cleaning systems of corals. Cloudy water also reduces light
   penetration in the water, reducing the light needed for
   photosynthesis
6. Wave action: coral reefs prefer areas of high-energy wave action. This ensures freshly oygenated water. It helps to clean out any trapped sediment. It brings in microscopic plankton-a food source for the corals. ln areas that are too exposed, however, corals can be easily destroyed.
7. Exposure to air: corals die if they are exposed to air for
   too long They can only survive and grow, therefore, at the level of the lowest tides.

Question 4

Explain why the methods used to protect a coastline have to be carefully planned

Question 5

Describe how a spit and a bar may be formed on a coastline

Answer 5

Spits and bars are formed when the process of longshore drift is in operation.

Longshore drift moves sand and shingle along a coastline. It takes place when the waves hit the beach at an oblique angel and break across the beach rather than straight up and down the beach.

When the waves break, their swash transports sand and shingle up and across the beach. This is called swash

When the wash runs out of energy it returns back down the beach carrying the sand and shingle with it. this is called backwash.

As the process is continually repeated it moves sand and shingle along the coastline. IF there is a break in a coastline such as a river mouth, longshore drift causes sand and shingle to build up so that the beach starts to grow away from the coast forming a spit.

If the spit continues to grow, it may evening reach right across a river mouth until it reaches the other side, when it becomes a bar.

The water trapped behind the bar is known as a lagoon.

Question 6

What is a headland?

Answer 6

A harder more resistant area of land projecting out to sea

Question 7

Name two other natural features which are formed by coastal erosion

Answer 7

Cliffs, wave-cut platforms, caves, arches, stacks, bays

Question 8

Explain how bays and headlands may be formed along a coast

Answer 8

1. If there are weaknesses in the rocks forming along a coastline such as sections of softer , less resistant rock or fault lines, differential erosion will take place.
2. As the softer less resistant rock is eroded at a fast rate through differential erosion, it forms a bay leaving the harder more resistant rocks projecting out to sea as headlands.

Question 9

For a named are which you have studied explain how and why coast sand dunes have formed in that area. You can sketch and label a diagram to help support your answer.

Question 10

Describe and explain formation of cliffs

Answer 10

Cliffs are formed when waves erode a coastline. Cliffs go through a repeated cycle:
1. They are undercut by hydraulic action, abrasion and solution/corrosion.
2.. This forms a cliff notice at the base of the cliff
3. This leaves the rocks in the cliff above unsupported so that they eventually collapse
4. The collapsed material is broken up by attrition
5. The process is continually repeated.

As the cliff retreats it leaves behind a gently slopping platform of rock called a wave-cut platform.