All The Question`s 4 Markers Aqa Coasts

This is the sort of material I will send - all the questions ever on the topics you study. This one is AQA Coasts for illustration purposes only.

COASTS 4 markers

AS Specimen 1 - Outline the role of wind in affecting coastal energy. [3 marks]

Allow one mark per valid point with additional credit for development.

Wind is responsible for the generation of waves as friction occurs at the surface of the water (1). Stronger winds blowing for a longer distance will generate bigger more powerful/destructive waves (d) (1). Wind also affects currents in terms of the direction that wind is blowing in (1). This has a direct bearing upon the potential for longshore drift depending upon the angle that the waves hit the coastline (1).

AS Specimen 2 - Outline how the coast is described as a natural system [3]

Allow 1 mark for each valid point with additional marks for developed points.

The coast can be described as an open system (1).

Inputs originate from outside the system (1) for example energy from waves, wind, sediment from rivers (+1 max for 1 example).

Outputs move to the outside, for example sediment accumulates above the tidal limit, sediment eroded from the coast is transported beyond the local sediment cell (1+1).

As an open system the coast is linked to other natural systems including the atmosphere with wind energy as an input of energy (1), sediments eroded from the coast transported into deep oceans become part of geological systems (1), with dissolved carbon from chalk and limestone cliffs moving through the carbon cycle (1).

AS 2017 - Outline characteristics of constructive waves. [3 marks]

Allow one mark per valid point with additional credit for development. Minimum of two characteristics for full marks.

Constructive waves have a long wave length i.e. horizontal distance between two peaks (1).

They have a low amplitude i.e. vertical height or distance between peak and normal sea level (1).

They are also characterised as having a stronger swash than backwash (1).

They have a longer wave period i.e. time taken to travel through one wave cycle (1).

AS 2018 - Outline the concept of eustatic sea level change. [3 marks]

Allow 1 mark for each valid point with additional marks for developed points.

Eustatic sea level change is a global change in sea level due to an actual fall or rise in the level of the sea (1) mark for any clear definition.

When global temperatures fall, during a glacial period, more precipitation falls as snow and is stored on land as ice and snow (1). Water cycled from the sea to the land (via evaporation, condensation and precipitation) does not immediately return to the sea so global sea levels fall (1) (d).

Or the opposite. As global temperatures rise, during an interglacial or due to enhanced global warming, more precipitation falls as rain, and snow and ice melt. (1). Less water is stored on land and returns to the sea, so global sea levels rise. (1)(d)

Some responses may refer to global sea levels rising due to the thermal expansion of sea water due to global temperatures rise due to the enhanced greenhouse effect (1).

Some responses may refer to changing global sea levels due to the changing geometry of ocean basins over geological timescales (1).

Allow max (1) (d) for support with data about levels/rates of sea level change over a given time.

AS 2019 - Outline characteristics of high energy coasts. [3 marks]

Point marked. Allow 1 mark for each valid point with additional marks for developed points.

High energy coasts:

tend to have exposure to strong and steady prevailing winds (1) that create high energy waves (1) (d)

Generally have an open uninterrupted aspect with a large fetch (1)

tend to have rates of erosion greater than deposition (1)

may have greater exposure to tropical storms (1)

Often have erosional landforms including headlands, cliffs and wave-cut platforms (1)

experience processes that tend to straighten the coastline (1), with material eroded from headlands being deposited as beaches that smooth-out former irregularities in the coastline (1)(d).

Specimen 1 - Explain the concept of the sediment cell. [4 marks]

Allow 1 mark per valid point with extra mark(s) for developed points (d).

A sediment cell is a closed system usually bounded by headlands or a change in longshore drift (1).

Within a sediment cell, there is erosion, transport and deposition of sediment within a long term cycle (1).

The only inputs into the sediment come from erosion from the sea bed or land (1).

There is little or no movement of sediment between cells (1).

Human activity such as beach management can interrupt the natural system creating imbalance within the cell leaving some areas at risk of erosion (1).

Specimen 2 - Explain the difference between eustatic, isostatic and tectonic sea level change. [4]

Allow 1 mark for each valid point with additional marks for developed points (d).

Eustatic change is a global change in sea level, whereas isostatic is a more localised/regional change of the land relative to the sea level. Tectonic change is also a local/regional scale change in the land relative to the sea level (1 +1 with development).

Eustatic change is brought about by a global change in the sea level relative to the land. During an ice age, sea levels drop relative to the land. Isostatic change results from the

Local impact of ice upon the land for example as ice melts the pressure release can cause an isostatic rebound whereby the land rises above the sea level at a local level.

Tectonic change is brought about by tectonic activity usually at plate boundaries. This can cause dramatic and immediate changes to the land relative to the sea (1 + 1 + 1 for development).

Some may go further and make links to landforms by way of explanation, e.g. Eustatic change Fjords, Isostatic change raised beaches. Tectonic changes formation of ridges or Fold Mountains. (1 +1 for development)

Max 3 marks if all three processes are not clearly distinguished

2018 - Outline the processes which lead to the development of barrier beaches. [4 marks]

A barrier beach is usually formed as an extension to a spit (1).

Longshore drift moves sediment along the coastline until there is a change in the coastline (1). A spit develops, usually in a bay and once the spit develops across the whole bay, a barrier beach forms (1). Barrier beaches are unlikely to form in estuaries as the out coming force of freshwater will always keep part of the estuary clear (1).

Colonisation by vegetation can stabilise the barrier beach and trap further sediment keeping the barrier beach above sea even at high tide (1).

Depending upon the climate the landward side may be colonised by mangroves in the still lagoon, which adds further stability (1).

2019 - Explain the development of saltmarsh environments [4 marks]

Salt marshes tend to develop in sheltered estuaries behind spits (1). As the spit develops, the area behind it becomes sheltered (d).

Silt is deposited by the river which gradually builds up to form an inter-tidal mud flat (1). The mud flat continues to build and rise above sea level with the addition of further silt (1).

Vegetation which is highly adapted to environment colonises the mud which itself traps further sediment (1).

The salt marsh environment is colonised by halophytic vegetation (1).

AS 2020 - Outline the process of coastal hydraulic action. [4]

Allow 1 mark for each valid point with additional marks for developed points.

This is a process of marine erosion (1).

It refers to erosion via the sheer force of water alone without any debris (1).

With high energy waves this can exert enormous pressure on the rock surface (1), weakening or breaking off rock particles (1d).

It is also referred to as wave pounding (1).

Accept reference to cavitation or wave quarrying (1).

2020 - Outline the process of sub-aerial weathering in the development of coastal landscapes. [4]

Allow 1 mark per valid point with extra mark(s) for developed points (d). For example:

Sub-aerial weathering involves the action of rainwater and insolation upon landforms in the coastal landscape (1).

Here material is broken in situ, rocks are weakened and can contribute to sudden large-scale movements (1).

Chemical weathering occurs when weak carbonic acid in rainwater attacks limestone cliffs (1). This leads to the formation of karst landscapes (d).

Mechanical weathering occurs when repeated freezing and thawing of water absorbed in pervious rock leads to the breakdown of rocks and the emergence of pronounced cracks in the bedding plain and rock strata (1).

Biological weathering refers to the burrowing of plants and animals into the rock at the coast. This can lead to the break-up of rock as well as the weakening of the rock by species which attach to rock (1).