Past papers on coasts- june 2011 (examiner answers-end of handout) January 2011

low wave height (1) and large gap between waves (1) – long wave length (1).

Must locate where waves breaking; swash/backwash. 2 x 1 (2 marks)

3 (a) (ii) Reference to “deposition” being more important than “erosion” (1). Swash stronger than backwash (1). This will result in the build-up of material on the beach (1) steeper gradient of beach and forms such as berms, cusps will result (1). 3 x 1

3 (b) Sub-aerial weathering is where the effects of the weather on land has an impact on the coast (1). This includes freeze-thaw weathering (rain water); exfoliation; solution; biological weathering – up to 3 marks on any one process, 1 for a list of types. 1 mark minimum for explicit identification of role – i.e. that rock is weakened by the processes (1) so that subsequent removal of material by waves is made easier/faster (1).All marks can be awarded on this aspect.

3 (c) The headlands are composed of a harder, more resistant rock and the inlets – the bays – formed of a softer rock. The geology is a significant factor in leading to the sequence of headlands and bays. The different rock types are arranged at right-angles to the coast and are, therefore, seen as being discordant. The less resistant rocks that ultimately form the bays are eroded faster as they are less resistant to erosion. There

should be reference to specific erosion process. Wave refraction means that the more powerful waves are concentrated on the headland; leaving gentler low energy waves in the bay, encouraging the build-up of material and forming a beach at the head of it. Headlands and bays can also form where the geology is concordant with the coast – the bands of rock going parallel to it. Here, the sea may break through the

more resistant material on the coast and then the rate of erosion is accelerated as the soft rock is eroded to create a bay. Candidates can refer to either one or both of methods – but both not required for Level 2.

Level 1 (1-4 marks)

Begins to explain. Sequence will be incomplete. Some use of appropriate terminology present at the higher end.

Explanation focuses on structure and differential erosion – which is understood.

Sequence given so that resulting landform is clear. Appropriate geographical terminology is used.
3 (d) See handout on essay questions

*January 2010

Study Figures 5a and 5b which show part of Happisburgh, Norfolk, in 2002 and 2007

respectively.

(a) (i) Oultine evidence that suggests marine erosion is occurring along this coast. (4 marks)

Evidence should relate to the land area – two houses gone on the left of the photo and one at bottom plus outbuildings of another property (1). Gardens are shorter (1). Road ends abruptly (1) presence of revetments (1). The shape of the coast is different with a bay-like feature being present on the left (1). The coastal protection/revetments have been washed away (1) and there appears to be more debris on the beach to the left of the photo, indicating greater activity (1). Lack of vegetation on cliff face (1). Cliff line has moved inland/retreat of coastline (1). Any valid point. 4 x 1 per basic point; 1 x 1 per developed point

Very strong winds/storms (1).

Ineffective as they have not been maintained (1). Made out of wood so not very strong or normal waves too powerful (1). Sections are clearly missing (1). Possible reasons why they have not been maintained such as a change in policy – managed retreat versus ‘hold the line’ (1) Not cost effective (1) – given area protected – as seen as worth outlay (1). May also refer to impact following loss of sections – e.g. base of cliff

now exposed to waves (1); beach removed due to loss of protection in front of cliffs (1) and so cliffs erode. Mass movement on cliffs cannot be prevented by revetments.

The main process is likely to refer to longshore drift. There should be reference to the two components of swash and backwash and how the angle of approach determines movement along the beach. The process is responsible for the shifting of material along the beach. There should be reference to processes such as saltation, traction and suspension. Reference to transportation by wind.

Sea level change is the result of either eustatic or isostatic change. Eustatic change is a global change in sea level relative to the land. These can be a fall in sea level – as occurred during glaciations or a rise in sea level as is the current situation. This is the result of water being added following temperatures warming, glaciers melting and

thermal expansion as oceans warm. Current concern regarding global warming would come into this category. Isostatic change occurs on a local level. Again, relative change may be positive or negative. This is the result of ice melting on land masses

and the loss of the additional weight causing land masses to readjust and ‘bounce up’. Similarly, plate movement at subduction zones may cause the land to rise relative to the sea. Conversely, with additional weight e.g. where there are deltas being created of substantial size, the land will sink due to the additional weight.

These are sections of coastline (1) where overall there is a balance between erosion and deposition within the cell (1). They are often split into sub-cells where there are specific inputs of materials whose transportation is then monitored (1). Clear ‘boundaries’ define them such as headlands (1). They represent closed systems theoretically (1). Thus, there is no transfer between the cells of material (1). There is a

debate about the extent to which this is true - with exemplification (1).

May refer to an example to illustrate (1).

4 x 1
(b) Explain the contrasting locations of the beach landforms shown in Figure 4. (4 marks)

Storm beach - at back, near cliff line - represents ridge where material is thrown by swash during extreme conditions (1) and thus, is above the level of high spring tides (1). Berms are formed by the swash during high tide (1) - the ridges at the back of the beach represent the section highest up the beach where material was deposited in a particular tidal cycle (1). Cusps form where sand and shingle meet and the gradient begins to steepen (1). This is due to strong swash and stronger backwash (1) - the

strong scouring action removes material, especially from the centre of the semicircular depression creating the cusp (1). Runnels are depressions in sand between ridges left as tide goes out (1) linked to breakpoint of the waves (1).

(c) Describe the characteristics of spits and explain their formation. (7)

These are long, narrow ridges of sand and/or shingle that are attached to the land at one end - proximal end. The distal end is in the sea and often extends partly across an estuary. This end can be hooked and is likely to change its position over time. Salt marsh often develops behind and sand dunes often present. They form due to the presence of a lot of material; the presence of the process of longshore drift, the dominance of constructive waves and the appropriate coastal configuration - presence

of an estuary or a change in direction of the coast.

Examples, illustrations are both valid areas of exemplification.

Case study is required here and content will vary depending upon that selected. Expect to see Holderness, North Norfolk, but could be one beyond UK.

Physical consequences - involve the undercutting of cliffs leading to collapse; mass movement processes of slumping, sliding and falls are also significant. Loss of land is an end result, causing coastal retreat. Socio-economic consequences - relate to the knock-on effects of loss of land. This is only significant in this context where there are people present or major installations - farmland not viewed as significant. Thus, loss of buildings - and even significant parts of settlements; issue of insurance; deaths/injuries; impact of the threat of and ultimate loss of home/livelihood; debate regarding coastal protection and cost of this and strategy adopted.

Level 1 (1-6 marks)

Describes some consequences. May focus on limited range - may be one-sided.

Points made are simple and random. No reference to a case study – generic answer.

Case study of coastal management that seeks to link to question; not linked to socio-economic consequences.

Description is more specific and precise. Begins to target content to purpose - considers consequences in an organised way. Some reference to both categories, although there may be imbalance. Coastal management clearly linked to socio-economic consequences. Points are supported by case study in places.

Tentative/implicit assessment of relative importance.

Level 3 (13-15 marks)

Clear, purposeful description of consequences. Both categories are addressed in a balanced account. An organised account that is purposeful in responding to the question. Case study is used to support answer. Clear, explicit assessment of relative importance.

2 x 1 – e.g. cliffs via wave erosion, cliffs via landslides, river carrying silt into sea, transport by waves of offshore sediment.

The impact of temperature change/freeze thaw weathering (1) +1 for explanation of the

process. An awareness that material is weakened and then can be eroded more easily

by the waves (1). There is an increase in instability resulting in an increased likelihood

of mass movement (1). Can refer to the impact of wind and rain. May consider impact

on certain types of rock of chemical weathering. 3 x 1 or 1 x (1+1) +1.

Constructive waves are relatively low and long – elliptical in cross section (1) whereas

destructive are high and steep – circular in cross section (1). Destructive waves have a

higher frequency (1), 6-8 versus 10-14 per minute (1). The swash is dominant with

constructive waves (1) and the backwash with destructive waves (1) – explanation of the significance of this (+1 for each).

(c) Explain the formation of landforms typical of coastlines of emergence. (6)

Response should show understanding of the term emergence and its cause(s) – that

landforms result from an increase in land height relative to the sea. Such changes are

usually the result of an isostatic change in sea level where there is a local (rather than

worldwide) change in the height of the land usually caused by the melting of glaciers and the recovery of the land from the pressure exerted by the weight of the ice. Areas of land now exposed are being acted upon by the sea to create a new shoreline. Above

this are raised beaches – now beyond the reach of the waves and often a fossil cliff line

and other relict features. Case study information likely to refer to west Scotland or

Wales.

(1-2 mark)

May be imbalance between the two aspects. (5-6 marks)

Content will depend on case study/studies used. Costs likely to relate to –

Economic – cost of protection and differences between different aspects’ funding of

scheme and sources. Environmental – appearance and knock-on effect of certain strategies.

Benefits likely to relate to – Economic – saving of areas of land, housing, transport routes, industry, etc. Social – maintaining people’s homes, communities.

Environmental – depending on scheme – natural look of coast, preserving habitat.

There is specific and detailed reference to case study in support.

Clear explicit comment which reflects earlier content. (10-15 marks)
Specimen paper 2 (not in booklet)
(a) What are tides? How do tides influence the formation of coastal features?

(4 marks)

Tides are movements up and down, about twice daily, of the water adjacent to the coast (1). They are caused by the gravitational pull of the moon (1). The active area of coastal erosion lies more or less within the area between the points of lowest and highest tides (1). Only if the high tides reach the cliff line the cliffs will gradually be

eroded back (1). Between high and low tide the main processes of transport, abrasion, attrition, sorting, etc. by marine processes will take place (1).
(b) Study Figures 4 and 5. They show the coastline of Pembrokeshire.
Figure 4 Figure 5



Describe the coastal landforms and explain how marine and sub-aerial

processes have combined to produce these landforms. (7 marks)
The surface of the land appears to slope moderately steeply to the sea. On the headlands this slope continues unbroken to the coast, but in other places the sea appears to have eroded the coastline back to form cliffs. The general land surface will have been formed by subaerial processes of weathering and erosion, mainly due to runoff of rainwater, and weathering and mass-wasting. The cliffs along this stretch of coast are formed in steeply dipping, almost vertical beds of rock. In some places, where a hard layer of rock forms the cliff, it is almost vertical. In some places stacks and stumps can be seen just in front of the cliff line. In Figure 4 it seems as though one or more arches may have formed or be forming as the sea picks out a layer of softer rock. The Stacks are not ‘text book’ examples because the vertical strata make them more like thin slabs which are easy to erode by the marine processes of hydraulic action, abrasion and attrition. Sub-aerial processes do not seem to be having much influence on the cliffs today as they do not appear to have been worn down much more than they were by the general slope of the land surface…until the surface is

interrupted by the cliff line.

(c) Choose one of the following coastal management strategies:

● gabions

● groynes

● barrages

Describe the technique and explain how it helps to protect the coastline.

(4 marks)
e.g. groynes

Groynes are low walls built out at right angles to the coast, across a beach (1). They are designed to stop, or slow down the process of long shore drift (1) and trap the sand or gravel on that beach (1). Without the groynes swash moves material up the beach at the angle of the winds, then backwash moves it straight back down to the sea

(1). Repeated over time this moves the material along the coast, in the direction of the most frequent powerful waves (1). By interrupting this process of longshore drift and trapping the sand the groynes protect the beach and the coastline (1).

(d) See handout on essay questions

Response should show knowledge and understanding of the meaning of coastal protection and its various aims (1), contrasting hard engineering as involving direct and physical methods perhaps working against the grain of natural systems whereas softer approaches being interventions more likely to be working with the grain of natural processes and likely to be more in balance with local eco-systems and coastal processes, less likely to disrupt coastal cell functioning, likely to be more sustainable and so on. (1-3). Language which explicitly emphasises distinction (1). Both types needing reference for more than 1 mark. Distribution in terms of initial and ongoing maintenance. (1).

Response should show an ability to accurately read and interpret the map with contrast

predominantly between southern Delta Region characterised by hard approaches with

reference to the evidence (1-2) compared with sand dunes coast of the central coastal region being conserved and managed rather than transformed (1-2). Judicious comment about the balance being related to the physical conditions, e.g. the contrast between the complex delta of major rivers in the south and its vulnerability to flooding compare to the continuous belt of dunes in the centre affording different levels of risk and opportunity for intervention (1-2 depending on detail). Some comment on balance is necessary for full marks. Accept measured statements about approximate balance or hard v soft, or soft v hard, as evidence is not conclusive from map. Statement which emphasizes hard or soft engineering only (1).

• Tides, tidal change, seasonality depending on local/regional conditions.

• Varying weather conditions, idea of stability and equilibrium disrupted periodically by major storm events sometimes causing longer term changes. Idea of change is one /cell causing change is another coastal element, ok as long as not overdone.

• Longer term cycles of geomorphologic processes of erosion, transportation and deposition. Models of coastal landform development related to dominant erosional and/or depositional processes related to different contextual factors, e.g. geology/lithology/structure; location/setting.

• Sea level change (isostatic/eustatic) cyclical or long term related to glaciation/deglaciation and its impact on coastal profiles and specific features associated with it such as raised/fossil beaches, wave cut platforms and other relic features; fjords/rias, etc.

• Accidental human impact on the global scale notably climatic change, global warming and predictions of rising sea levels in the near future.

• Deliberate human impact such as management of coastal environments both successful and unsuccessful – comment on the significance and longevity of these within wider spatial and especially temporal contexts might indicate mature geographical thinking.

• Case study material/exemplars might come from anywhere. In offering valid comparisons and contrasts which inform a response and give it substance and credibility the potential of making broad and specific comparison between LEDCs and MEDCs. Contrasting examples are extremely likely to produce syopticity, etc.

Discussion requires a debate to be held and a view should be stated. Any reasonable conclusion can be credited as long as measured, realistic and related to preceding content.

*January 2005



(a) Outline processes of erosion associated with the formation of the wave cut platform shown in Figure 1. (4)

Response should show knowledge and understanding of the processes of erosion associated with the development of a wave cut platform. Credit statements on abrasion/corrosion, attrition, hydraulic impact, cavitation and solution (1-3 for each process depending on detail/development). Allow reference to sub-aerial erosion if valid. There must be more than a mere mention of a process to attract credit so that a list is not creditworthy. There are varying ways to full marks (1+1+1+1, 1+2+1, 2+2, 1+3) but at least two processes must be outlined for 4 marks. Statements about weathering are not creditable. Allow 1 mark for overview of erosion leading to formation of wave cut platform.

Response should show knowledge and understanding of relevant aspects of geology either lithology or structure or elements of both. Lithology - different types of rock susceptible to different types of erosion particularly distinguishing between chemical and physical erosion processes; also offering different resistance to erosion, affecting rates of erosion. (1-4 depending on detail/development). Structure might be at different scales but jointing and stratification into bedding planes allowing water ingress, presenting lines of weakness leading to differential erosion both in profile and plan form. (1-4 depending on detail/development). Concordant/discordant coastlines and associated patterns of coastal development (1-2). Both nature and effect should be outlined for 4 marks. Solution is acceptable as a form of erosion.

Response should show knowledge and understanding of wave cut platform processes and cliff retreat. At a simple level the standard model of development should be outlined referring to continuing cliff retreat with undercutting at the wave cut notch and slumping/collapse with gradual planation and extension of the platform and removal of the stumps and stacks. Development of beach material on the platform. Over time, an ever-extending wave cut platform means energy dissipation so that eventually cliff undercutting and retreat ceases and sub-aerial processes dominate with slope decline at the cliff. Relevant exemplification, which contributes to illustration of points made, should be credited.

Simple understanding shown by straightforward statements about cliff retreat,

extension of wave cut platform and removal of stacks, stumps.

Level 2 Generic descriptor (4-5)

More refined understanding indicated by fuller statements with illustration and some detail on cliff retreat, extension of wave cut platform and removal of stacks, stumps, suggestions of gradual reduction in energy levels and diminution of marine processes. Full statement on how without reference to why.

Clear understanding of energy aspects with outline of cliff retreat extended by clear statements on energy dissipation, diminution of marine processes, dominance of sub-aerial processes and slope decline.

The response can be exemplified and illustrated at a variety of scale and contexts and the assigned task enables a discussion of values and policy aspects to be incorporated.

Appropriate content might encompass a very broad range, as this is a question to which there are very many potentially relevant responses:

The impact of natural processes on coasts and human attempts to manage them can be expected to figure prominently in most responses and will be perfectly creditable. A range of different processes for example marine, atmospheric processes and their problematic impacts to include coastal erosion, sudden geomorphological events such as land slips, storm events including surges, flooding might be reviewed with the possible human responses designed to alleviate, reduce or remove the risk.

Potential for different scales of response could well be a focus on management for a variety of reasons, flood prevention, control of erosion, maintenance of coastal forms, environmental conservation, navigation and so on. Such elements in a response could extend back into review of vulnerability of coasts to environmental threat. References to prospective or beginnings of sea level change associated with global warming and/or isostatic adjustment are potentially relevant but should be suitable measured and relate to the present or very near future i.e. not outline reasons for future management 10 or more years hence. Also creditable is content which demonstrates that management/intervention tends to prompt further management e.g. because of unforeseen effects elsewhere. Exemplification at different scale is possible form local to regional and small scale to national such as the Dutch coast.

The question clearly requires a reasoned and discussive approach and the response should come to a clear conclusion perhaps summarising the reasons or even querying the statement - any conclusion is creditable as long as it is reasonable and related to the preceding contents and discussion.

Response should show knowledge and understanding of the causes of sea level

change - both eustatic and isostatic explanations are creditable. Eustatic causes

being connected with glacial expansion before 16000 BP and contraction after

18000 BP glacial melt in post glacial period (1-4 detail and development, e.g by

fullness of explanation, illustration, exemplification). Thermal expansion (1-2).

Associated isostatic changes linked to depression/rebound of crust under ice or

tilting as in more local case of southern/northern North Sea basin (1-4 depending

on detail and development). Credit careful account of temporary sea level

changes linked to storm surge. Thus full accounts of post-glacial history in terms

of isostasy or eustatic change may be fully credited - however a mix of the two

can be expected and would be equally creditable for 2+2 or 3 + 1. Tolerate

iso/eustatic confusion as long as accurate, by subtracting 1 mark from total mark.

(b) Outline the evidence for higher sea levels in the past which might be found in a coastal environment. (4)

Response should show knowledge and understanding of features associated with

falls in sea level, most likely relic cliff lines associated with retreat and subsequent dominance of sub-aerial degradation processes reducing slope angles etc. and perhaps linked with depositional features such as alluvial flats and fans etc or indeed another seaward active cliff line depending on time scales. Alternatively/additionally raised beaches perhaps associated with degraded relic cliff line and other erosion features such as notches above existing wave cut platforms; presence of naturally cemented beach material such as shingle. (Each element 1-3 marks). Thus, an outline of at least two is necessary for full marks. Geological rather than geomorphological explanations, e.g. presence of limestone as evidence for changing sea levels 1 mark.

(c) Some models predict that sea levels will rise by up to 5 metres in the next 100 years. Comment on the consequences for coastal environments. (7)

Response should show detailed knowledge and understanding of likely

consequence of a rise in sea level. An increase in sea level by 5 metres within 100

years is at the extreme end of the spectrum of predictions and would be pretty

momentous and thus a variety of responses might be expected and can be

credited. Physical and human consequences might be legitimately distinguished.

Physical consequences might be the re-configuration of coastlines, flooding of

low-lying areas, loss of coastal land, renewal and/or redistribution and/or changes

in nature and intensity of erosion and deposition processes, allow and credit some

detail on how this may affect particular settings. Additionally or alternatively, the

responses might focus on the human consequences, dislocation and disruption to

settlements, economic activity, transport and so on. Both physical and human

consequences may creditably prompt some outline of human intervention and

management responses to sea level rise. Despite the momentous nature of such a

rise in sea level comment should be measured - it might include the rate of

change, an overview of impacts, the relationships between the consequences,

qualifying remarks about human responses to try and manage the consequences

adopting different strategies. Relevant exemplification, which contributes to

illustration of points made should be credited.

Level 1 - Generic Descriptor (1-3)

Simple statements about physical and/or human dislocation, or more detailed

statements lacking circumspection or measure.

Level 2 - Generic Descriptor (4-5)

More detailed statements about physical and/or human dislocation with some

sense of circumspection. Sense of comment.

Level 3 - Generic Descriptor (6-7)

Detailed statements about physical and/or human dislocation with a clear sense of

comment, e.g. reference to balance of effects, their inter-connections, their

manageability, their inevitability, etc.

Response should show knowledge and understanding of the meaning of high and

low energy coasts, contrasting high energy with destructive storm waves (1-3)

with long fetches (and often macro tidal) (1-2) landing on mainly shingle beaches,

having high wave height and fairly short wave length (1-2) with a fairly weak

swash and a strong backwash (1-2) as against constructive (swell) waves falling

on sandy beaches. Judicious statement referring to coasts being along a

continuum between high and low energy (1-2).

Do not double credit opposites. No credit for examples unless they actually

distinguish. Answer that refers to one only (1)

Response should show an ability to describe spit formation as being drift aligned, direction of long shore drift and dominant waves (1-2) with a change in coastal

orientation (1-2), sediment supply exceeding removal (1-2). Reduction in energy

leading to deposition (1-2). Some credit for use of appropriate terminology

(proximal and distal etc., rapid changes (as illustrated on Figure 1) and maximum

length (1-2). Reasons for recurved spit or ‘hook’ (1-2).

Response should show detailed knowledge and understanding of the problems

resulting from management of high energy coastal environments, specific links

between management strategies, coastal processes and down drift effects.

Vulnerability of coasts accentuated by geology, lithology, storms and human

development. Problems can include both physical and human. Relevant

exemplification could reasonably come from many locations but is likely to

include Holderness, Christchurch Bay, etc. Strategies can include hard

engineering (sea walls, groynes, gabions etc.) and/or soft engineering (beach

replenishment, sand dunes etc.).

Must refer explicitly to high energy coasts and management, as well as costbenefit

issues, aesthetics etc.

Some awareness of coastal management strategies and some idea of general

effects; quite detailed coastal management but no problems.

Level 2 – Generic Descriptor (4-5)

Fuller awareness of two problems within high energy context; or one issue in

depth with exemplification can reach Level 2.

Level 3 – Generic Descriptor (6-7)

Detailed awareness of at least two problems clearly embedded in high energy

coasts with relevant exemplification and with possible comment referring to their

resolution.

Understanding of effect of variations in rock resistance on coastal shape (1-2).

Actual examples (e.g. Atlantic coast of SW Ireland) (1).

Use of bay/headland development, wave refraction – a diagram that is well

annotated or clearly explained in the text can have credit here (1-3).

Effect of prevailing and/or dominant winds – especially since Figure 1B is SW

orientated (1-2). Concordant/discordant coastlines (1).

Detailed outline of one coastline Max. 2. No mention of bays Max 3.

Must deal with both coastlines for full marks.

(b) Outline maritime factors that influence the rate of erosion along a coastline. (4)

Answer should refer to rates of erosion.

Changes in sea level (eustatic and isostatic) (1-3).

Direction of dominant wind, longest fetch, storm/extreme events (1-3).

Depth of water offshore. Inter-tidal range (1-3).

Constructive/destructive waves, high/low energy coasts (1-3).

Requires both name and appropriate location for credit. (1 mark for each correctly named

and located) only 1 credit for each.


(b) Outline how a wave-cut platform develops. (4)

Also known as shore or inter-tidal platforms, which suggests the upper and lower limits of the platform, which slopes between 0.5º and 4º. Clearly a feature of erosion, relevant

processes include abrasion (1-3) etc., leading to a wave cut notch in the cliff. As the cliff retreats the platform is extended landwards(1-3). Often covered in rock debris from the combination of weathering and marine erosion. This debris is temporary, being either reduced by attrition and or removed by waves – often laterally by long shore drift (1-3). Removal of debris exposes cliff to further erosion but this becomes less effective due to frictional effect (1-2). No credit for examples.
*January 2008

(a) How are raised beaches formed? (4)

A raised beach is an emergent coastal landform. Raised beaches are former beaches or wave cut platforms often with relic cliffs behind them – credit some idea of how these are in themselves formed (1-3). They are raised above the shore line by a relative fall in the sea level (eustatic) (1-2). It may also be as a result of the isostatic recovery of the land. Can also be formed when tectonic activity, such as earthquakes, causes the

level of the land to rise (1-2).

(b) Compare and contrast rias with fjords. (4 marks)

Similarities – “drowned” / valleys / caused by post glacial isostatic readjustment (1-3).

Must compare and contrast for full marks.

Only two processes are required along with some explanation. If more than

two are offered, take the marks for the best two of those offered. Examples are

not creditworthy here. There is no credit for merely naming the process.

Since this is an often well-learned idea, it is important that the answer is in the correct sequence as well as with the correct information. A well-annotated diagram or series of diagrams can gain credit here. Since processes of erosion are required in part (a) there is no credit for them here. A headland is attacked by erosion, usually at points of weakness, faults, etc (1-2). This leads to the formation of caves, possibly blow holes and eventually an arch (1-2). The erosive processes continue and eventually the roof of the arch collapses, leaving a stack (which will be worn to a stump and eventually

disappear) (1-2). Credit appropriate use of photo (bedding planes, wave cut

platform, etc (1-2).

Landforms of submergence and emergence

When waves approach an irregular coast they become increasingly parallel to the coast. Since headlands are approached first (and are often more steeply shelving offshore) it is the shallowing of the sea bed that has an impact here first, interrupting the elliptical movement of the particles and reducing wave velocity and increasing wave height (1-3). Since wave energy is proportional to wave height, this has the effect of

concentrating more wave energy round the headland (shown by the orthogonals) and further increasing the wave height and therefore its erosive power. The opposite occurs with the waves reaching the bay (1-4). This is more evident in waves with a short wavelength as they are not influenced by the shelving bottom until they are closer to the shore (1-2). Credit appropriate use and/or annotation of the diagram.

(b) Distinguish between constructive and destructive waves. (4)

This is the .distinguish. question. Examiners are reminded that single statements about one type of wave are not creditworthy unless matched to a corresponding one for the other type . these can be directly linked or by juxtaposition (dealing with constructive waves first and a corresponding section on destructive ones) or where a comparative

term (e.g. less frequent) is used. The table below gives the basic points but there is also credit for more detailed distinctions such as the elliptical changes in motion of water molecules, angle of wave approach, etc. as well as awareness that the

key difference is the wave frequency.