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Chapter 1

An introduction to the coastal

geomorphology of Great Britain

May, V.J. & Hansom, J.D., (2003), Coastal Geomorphology of Great Britain, Geological Conservation Review Series, No. 28, Joint Nature Conservation Committee, Peterborough, 754 pages, illustrations, A4 hardback, ISBN 1 86107 484 0For more information see: http://www.jncc.gov.uk/page-3012

Coastal research in Britain

3

INTRODUCTION

This volume summarizes the results of the siteevaluation and selection programme of Britain’scoastal regions that was undertaken between1980 and 1990 as part of the GeologicalConservation Review (GCR), although the siteevaluation phase of the Review is ongoing. Withthe aim of representing the highlights ofBritain’s coastal geomorphology, 99 sites (seeFigure 1.2) were selected eventually for this partof the GCR, to be considered for long-term con-servation under British law.

The descriptions of the GCR sites in this bookare intended not only to justify why it is impor-tant to conserve geomorphologically importantparts of our coast, but also to demonstrate themajor contribution that British sites have made,and continue to make, in developing our under-standing of coastal geomorphological processesand the features that they create.

ORGANIZATION OF THIS VOLUME

In the following sections of Chapter 1, anoverview of coastal research is followed by anintroduction to the coastal geomorphology ofGreat Britain – discussing geomorphologicalprocesses and their controls (a glossary of geo-morphological and technical terms is providedat the back of this book). There is a brief dis-cussion of the impact of coastal managementand engineering on the environment, and thechapter concludes with details of the rationaleand methods of selection of the coastal geomor-phology GCR sites.

Most of the GCR sites described in the presentvolume are dominated by one coastal landform,especially in terms of their associated researchsignificance, and this is the basis of their arrange-ment into chapters. This has the advantage thateach set of landforms can be introduced in termsof our understanding of coastal geomorphologi-cal processes and the linked landforms.However, while cliff site descriptions are dividedinto ‘hard-rock’ (Chapter 3) and ‘soft-rock’(Chapter 4), one chapter (Chapter 2) serves tointroduce them. Similarly, whereas it is conven-ient to separate out into successive chaptersgroups of sites representing gravel (‘shingle’)beaches, sandy beaches, and spits and tombolos,it is simpler to cover all three chapters (6–8) bya single introduction (Chapter 5). There followchapters on machair (9), and saltmarshes (10),

each with their own introduction. Finally theselected GCR sites include a number that arecomplex in their assemblage of linked geomor-phological forms, and so they have beengrouped into a final chapter (11) with the title‘Coastal Assemblages’.

COASTAL RESEARCH IN BRITAIN

K.M. Clayton

With its geologically varied coastline and high-energy coastal regime, much coastal researchhas been stimulated in Britain over the past twohundred years. Books describing the landformsand scenery of the British Isles have paid con-siderable attention to the coast, and descriptionsof many British sites have found their way intotextbooks about coastal forms and processes asarchetypal exemplars. Steers has published twovery valuable descriptions of the entire Britishcoast, one on England and Wales (Steers, 1946a)and the second on Scotland (Steers, 1973).Perhaps it is because of the diversity of Britishcoastal forms – as well as the long history ofstudy – that British authors have contributed sev-eral key texts on coastal geomorphology to theliterature at a variety of levels of technical com-plexity (e.g. Pethick, 1984; Carter, 1985, 1988;Hansom, 1988; Bird, 2000, Haslett, 2000).

There is considerable bias in the publishedliterature, however. In geographical terms, thenorth and west of Britain are poorly represent-ed; in topical terms, soft-rock coasts have hadmore attention than hard-rock, and low coastshave had far more than cliffs. Coasts that changeform more rapidly have also received greaterattention, whereas hard-rock cliffs, which seemto change very little in a lifetime, have receivedmuch less.

A computer-database bibliography of some9000 items has been accumulated covering alarge proportion of all papers and books pub-lished on the geomorphology of the British Islessince 1960, together with a selection of paperspublished before that date (based on Clayton1964, together with GeomorphologicalAbstracts, Geographical Abstracts and GeoAbstracts). Of these, 1400 are classified underthe heading ‘Coasts’. Table 1.1 gives a break-down by date (the list is not comprehensiveuntil after 1960, so the two columns are notcomparable, but the fall-off in rate of publicationof coastal papers since 1989 seems quite remark-

An introduction to British coastal geomorphology

4

able, and presumably is matched by a growth inother geomorphological topics, no doubtQuaternary geomorphology in particular). Table1.2 gives the number of published papers andbooks indexed under particular keywords (thecategories are not exclusive), and gives a goodidea of the relative cumulative interest in variousaspects of coastal geomorphology. Figure 1.1 isa map that displays the number of items in thebibliography dealing with coasts, allocated tothe 100 km squares of the National Grid towhich they refer.

As Figure 1.1 shows, the geographical distri-

bution of published coastal research is veryuneven, with a clear bias to the south and east.The largest numbers are for TF (Lincolnshire,The Wash and North Norfolk) and SS (north andsouthern shores of the Bristol Channel).

Of course the length of coastline within a grid

HY

HP

HU

HY

NBNA NDNC

NGNF NJ NKNH

SD SE TASC

SJ SK TF TGSH

SO SP TL TMSN

ST SU TQ TRSS

SY SZ TVSX

SM

SR

SW

NR NT NUNS

NW NY NZNX

NM NONN

6

3 3

9 79

29 3211

82 815

34 160 91

75

26

104107

114 100128

9788

51

32

9 121922

14 42

32 40

Figure 1.1 Geographical distribution of UK coastalresearch, based on a comprehensive computerizedbibliography of books and papers on the geomor-phology of the British Isles, containing some 9000entries, compiled by K.M. Clayton. Of the 9000entries, some 1400 are classified as dealing withcoasts. These in turn are indexed under the 100 kmsquares of the National Grid and the number of pub-lished articles is shown (encircled number) for eachrelevant National Grid square, or combination ofNational Grid squares. As the map shows, they arestrongly biased to the southern half of Britain.Because some articles cover the coast in more thanone grid square, the total number of entries on thismap is 1671.

Table 1.1 Number of items in the computerized bib-liography of geomorphology of Britain that are classi-fied as ‘Coasts’ (total 1400), by year of publication.

Year Items

1830–1859 51860–1899 151900–1909 11910–1919 101920–1929 241930–1939 361940–1949 281950–1954 681955–1959 731960–1964 1021965–1969 861970–1974 1211975–1979 1971980–1984 2291985–1989 2091990–1994 681995–1999 102

Table 1.2 Number of items under selected keywords(some items appear more than once as several key-words are allocated to each).

Beach 284Erosion 267Sea level 186 Cliffs 126Saltmarsh 104Sand dunes 90Gravel/Shingle 86Littoral/Longshore drift 79Coastal protection 74Spit 66Coastal platform 42Accretion 27Sediment cell 3

The geological background

5

square varies considerably, but if we take the fol-lowing examples of grid squares that have a gen-erally linear coast without long indentations, wefind the pattern set out in Table 1.3. Clearly inthis analysis, such coasts as Dorset, Suffolk/Essexand Lancashire/south Cumbria are among themost studied, whereas Sutherland is among theleast. Therefore, Figure 1.1 helps to highlightthose areas of the British coast that are betterunderstood geomorphologically, and, perhaps,identifies those areas where further study mayhelp us to gain a more complete understandingof the coastal geomorphology of Britain.

THE GEOLOGICAL BACKGROUND

K.M. Clayton

The pattern of geological outcrops along theBritish coast (Figure 1.2) has a fundamental con-trol on the nature of the coastline. This is forseveral reasons, outlined below.

• Coastal topography: Underlying geologyhas influenced the topography of the land,and the detailed outline of the coast in largepart reflects the relief of the littoral zone.Rocks that are susceptible to erosion tend toform bays and inlets, whereas erosion-resist-ant rocks form headlands. Local differencesin the level to which outcrops adjacent to thecoast have been lowered by subaerial erosion– and the impact of such differences on thecoastal form – are seen best along the EnglishChannel coast, such as along the coast ofDorset, or demonstrated in such contrastingsituations as Beachy Head and the adjoiningPevensey Levels.

• Dissection in rocks of different strengths:Where relatively erosion-resistant rocks havebeen deeply dissected by erosion, the coastaloutline is complex, such as in westernScotland. Where weaker rocks have been dis-sected, former headlands and bays may havebeen truncated by marine erosion, such as theSeven Sisters in Sussex.

• Geological control on cliff profile: Rocks ofall strengths can be cut back by erosion toform cliffs, but weaker rocks generally failmore readily and so form sloping cliffs withangles from 20º to 40º, whereas erosion-resistant rocks are more likely to form near-vertical cliffs, such as at Duncansby, Caithness.In the more resistant rocks, the details of bed-ding and jointing commonly influence cliffform, both in plan and profile; thus seaward-dipping rocks are likely to suffer slide failureas basal erosion persists, leading to gentlerslopes than on horizontal or landward-dipping strata.

• Lithological control of landsliding: Whereweak rocks underlie stronger ones, landslidesare likely to occur; good examples areFolkestone Warren, now largely controlled bydrainage and ‘toe loading’, and Ventnor–Shanklin on the Isle of Wight, where seaward-

Table 1.3 Geographical analysis of the British coastal literature, using selected grid squares only.

Grid square Estimated Number Coastline lengthlength of of per number ofcoastline publications publications

SY (Dorset) 110 km 97 1.13 kmTM (Suffolk/Essex) 120 km 95 1.26 kmSD (Lancashire/S. Cumbria) 150 km 82 1.83 kmSN (Fishguard to Aberdovey) 95 km 35 2.71 kmNJ (south side of Moray Firth) 100 km 22 4.55 kmNZ (Durham/North Yorkshire) 130 km 18 7.22 kmNC (Sutherland) 150 km 9 16.67 km

Overleaf:Figure 1.2 Geological map of Great Britain, alsoshowing the locations of the Coastal GeomorphologyGCR Sites. The map shows sedimentary rocks classi-fied according to their age of deposition and igneousrocks according to their mode of origin. The num-bers in the key indicate age in millions of years (Ma).(Permit number IPR/26-45C British Geological Survey© NERC. All rights reserved.)

6

97

47

18

25

29

63

65

98

69

43

44

86

8526

27

4645

2838

62992324

37

4887

35

2219

3463

32

33

31

71

49

13

1530

202160513650

9414

16

66

68

6717

96

95

52

53

72

9057

76

91

9

42

77

78

79

8

1

81

80

8283

73

84 74 59

561

6

40 92 4154

2

3

70

39

75

4

10

793

88

89

N

0 100kilometres

55

58

56

11

12

55

56 57

75 58

73

61

70

68

66

656774

51 63

647271

69

28

17

1920

21 22

23

2425

26

27

34

60

59

62

54

Fig 1.2 key

Tertiary and marine PleistoceneMainly clays and sands. Pleistocene glacial drift not shown up to 65

Age

(Ma)

65–140

140–195

195–230

230–280

280–345

345–395

395–445

445–510

510–570

600–1000

500–1000

1500–300

Cretaceous Mainly chalk, clays and sand

MESOZOIC

Late Precambrian Mainly sandstones,conglomerates and slitstones

Lower Palaeozoic and Proterozoic Mainly schists and gneisses

Early Precambrian (Lewisian)Mainly gneisses

METAMORPHIC ROCKS

Intrusive: Mainly granite, granodiorite, gabbro and dolerite

Volcanic: Mainly basalt, rhyolite, andesite and tuffs

IGNEOUS ROCKS

SEDIMENTARY ROCKSCAINOZOIC

Permian Mainly magnesian limestones, marlsand sandstones

Devonian Sandstones, shales, conglomerates, (Old Red Sandstone) slates and limestones

Silurian Shales, mudstones, greywacke, some limestones

Ordovician Mainly shales and mudstones,limestone in Scotland

Cambrian Mainly shales, slate and sandstones,limestone in Scotland

Carboniferous Limestones, sandstones, shales andcoal seams

Jurassic Mainly limestones and clays

Triassic Marls, sandstones and conglomerates

PALAEOZOIC

UPPER PROTEROZOIC

22 South-west Isle of Wight23 Kingsdown to Dover, Kent24 Beachy Head to Seaford Head, East Sussex25 Ballard Down, Dorset26 Flamborough Head, Yorkshire27 Joss Bay (GCR Name: Foreness Point), Kent28 Porth Neigwl, Caernarfonshire29 Holderness, Yorkshire

Gravel and ‘shingle’ beaches (Chapter 6)30 Westward Ho! Cobble Beach, Devon31 Loe Bar, Cornwall 32 Slapton Sands, Devon33 Hallsands, Devon34 Budleigh Salterton Beach, Devon35 Chesil Beach, Dorset36 Porlock, Somerset37 Hurst Castle Spit, Hampshire38 Pagham Harbour, West Sussex39 The Ayres of Swinister, Shetland40 Whiteness Head, Nairnshire41 Spey Bay, Morayshire42 West Coast of Jura43 Benacre Ness, Suffolk44 Orfordness and Shingle Street, Suffolk45 Rye Harbour, East Sussex46 Dungeness, Kent

Sandy beaches and dunes (Chapter 7)47 Marsden Bay, County Durham 48 South Haven Peninsula, Dorset49 Upton and Gwithian Towans, Cornwall50 Braunton Burrows, Devon51 Oxwich Bay, Glamorgan52 Tywyn Aberffraw, Angelsey53 Ainsdale, Lancashire54 Luce Sands, Dumfries and Galloway55 Sandwood Bay, Sutherland 56 Torrisdale Bay and Invernaver, Sutherland57 Dunnet Bay, Caithness58 Balta Island, Shetland59 Strathbeg, Aberdeenshire60 Forvie, Aberdeenshire61 Barry Links, Angus62 Tentsmuir, Fife

Sand spits and tombolos (Chapter 8)63 Pwll-ddu, Glamorgan64 Ynyslas, Ceredigion 65 East Head, West Sussex66 Spurn Head, Yorkshire67 Dawlish Warren, Devon68 Gibraltar Point, Lincolnshire69 Walney Island, Lancashire70 Winterton Ness, Norfolk71 Morfa Harlech, Gwynedd72 Morfa Dyffryn, Gwynedd73 St Ninian’s Tombolo, Shetland74 Isles of Scilly75 Central Sanday, Orkney

Machair (Chapter 9)76 Machir Bay, Islay 77 Eoligarry, Barra, Western Isles78 Ardivacher to Stoneybridge, South Uist, Western Isles79 Hornish and Lingay Strands (Machairs Robach and Newton),

North Uist, Western Isles80 Pabbay, Harris, Western Isles 81 Luskentyre and Corran Seilebost, Harris, Western Isles 82 Mangersta, Lewis, Western Isles 83 Tràigh na Berie, Lewis, Western Isles84 Balnakeil, Sutherland

Saltmarshes (Chapter 10)85 St Osyth Marsh, Essex86 Dengie Marsh, Essex87 Keyhaven Marsh, Hurst Castle, Hampshire88 Solway Firth (north shore), Dumfries and Galloway89 Solway Firth: Upper Solway flats and marshes (south shore)90 Solway Firth: Cree Estuary, Dumfries and Galloway91 Loch Gruinart, Islay, Argyll and Bute

Coastal assemblages (Chapter 11)92 Culbin, Moray93 Morrich More, Ross and Cromarty94 Carmarthen Bay, Carmarthenshire 95 Newborough Warren, Anglesey96 Morfa Dinlle, Gwynedd97 Holy Island, Northumberland98 North Norfolk Coast99 The Dorset Coast: Peveril Point to Furzy Cliff

Hard-rock cliffs (Chapter 3)1 St Kilda Archipelago, Western Isles2 Villians of Hamnavoe, Shetland3 Papa Stour, Shetland4 Foula, Shetland5 West Coast of Orkney6 Duncansby to Skirza Head, Caithness7 Tarbat Ness, Easter Ross8 Loch Maddy–Sound of Harris coastline, Western Isles9 Northern Islay, Argyll and Bute 10 Bullers of Buchan, Aberdeenshire11 Dunbar, East Lothian12 St Abb’s Head, Berwickshire13 Tintagel, Cornwall14 South Pembroke Cliffs, Pembrokeshire15 Hartland Quay, Devon16 Solfach, Pembrokeshire

Soft-rock cliffs (Chapter 4)17 Ladram Bay, Devon18 Robin Hood’s Bay, Yorkshire19 Blue Anchor–Watchet–Lilstock, Somerset20 Nash Point, Glamorgan21 Lyme Regis to Golden Cap, Dorset

SEDIMENTARY ROCKSCAINOZOIC


8

dipping Cretaceous strata are still mobile.Where weaker rocks overlie more resistantstrata, ‘slope-over-wall cliffs’ occur (seeChapter 2); examples include the south-westEngland peninsula (where the upper cliffretains a periglacial facet) and the till-cappedJurassic cliffs of North Yorkshire.

• Control by interfluve level: Rock resistanceinfluences the general level of interfluves, andas cliffs cut back farther inland by wave action,cliff-height may increase as progressively high-er interfluves are encountered; maximum cliffheight would be attained at the point wherethe cliffline crosses the crest of the highestinterfluves. However, in many areas cliffs areappreciably lower than this potential maxi-mum, suggesting that the rocks are resistantenough to have prevented the landwardmovement necessary to attain the maximumpotential cliff height (or perhaps that the peri-od of stability since sea level reached its pres-ent position at that site has been insufficientto achieve much cliff recession).

It is clear from the foregoing that developmentof a map of relative rock resistance to erosion(Figure 1.3) is particularly useful for interpretingcoastal form. Whereas geological maps stressrock age and differentiation by lithology withinthe major age groups, coastal form reflectsmarkedly – in both planform and elevation –contrasts in rock strength, and it is the local con-trasts that lead to the detail and diversity of ourcoasts. The outcrop pattern is intimately linkedto rock strength (compare Figures 1.2 and 1.3;see also Table 2.1).

By studying the relative elevation and dissec-tion of rocks in Britain (using a database for thekilometre squares of the Ordnance SurveyNational Grid) a relative order of resistance toerosion was established for the 71 most com-mon (outcrops >500 km2) rocks in Britain(Clayton and Shamoon, 1998). While an exactfit to the resistance of rocks to erosion-ratesmeasured at the coast is unlikely to be achieved,the general order of resistance is likely to be sim-ilar, and this may aid comparison between sitesin future investigations. With six categories, thepattern shown in Table 1.4 emerges.

Therefore, geological maps of Britain areimportant documents in understanding coastalgeomorphology. Although Figure 1.2 is at asmall scale, broad connections between outcroppattern and the outline of the coast can be

traced; larger-scale maps, showing more detailedoutcrop patterns, emphasize the geological con-trol of coastal form at local levels still further.

Thus while there are differences between theolder and generally far more resistant rocks of

Low average

Weak

Very weak

Very resistant

Resistant

High average

0 200kilometres

N

Figure 1.3 Relative rock resistance for 71 differentoutcrops (divided by lithology and age) was estab-lished through computer analysis of data on altitude,dissection, and geology for a grid of kilometresquares covering Great Britain and the surroundingcontinental shelf. Six consistent classes were estab-lished using up to 19 variables in various combina-tions. White areas are unclassified. (From Claytonand Shamoon, 1998, fig. 1).

The geological background

9

northern and western Britain and the youngerand weaker rocks found in east and southernEngland, within each of these zones local con-trasts dominate the coastal geomorphology.From Flamborough Head in Yorkshire south-wards and westwards to the Exe estuary inDevon, the Chalk and sandstones that form thecuestas of the scarpland and vale landscape alsoform the major coastal headlands (FlamboroughHead, North Foreland in Kent, Beachy Head inSussex, and the Needles on the Isle of Wight, forexample, all on Chalk) and between them on theintervening clays or on till-covered littoralplateaux, wide bays, locally fronted by salt-marshes and sand dunes, alternate with lowcliffs cut into the low till-capped plateaux ofHolderness, Norfolk and Suffolk.

Geological influence on sedimentsupply into the coastal system

A further influence of geology on coastal geo-morphology is in the provision of sediment thatcan be incorporated into beaches. Beachesaround Britain vary considerably in their texture(from fine-grained sand to boulders) and in theirlithology (from shelly sands to flint cobbles) andreflect the local supply of material of appropri-ate dimensions. Some coarse sediments are stillbrought to the coast by rivers, especially inScotland and Wales, where gradients are steep

and coarse-grained material is readily transport-ed by floods. In contrast, very little sedimentother than mud (clay and silt) is now broughtdown the rivers of lowland Britain to the coast.Thus, especially in areas with more gentle inlandrelief, it is the delivery of sediment from offshoreas well as from retreating cliffs that has providedmost of the material for the local beaches.Boulders and coarse gravel are derived from ero-sion of resistant rocks in areas such as Scotlandand parts of the Welsh coast, their initial sizedepending on rock-joint spacing. Locally alongthe English coast, quartzites are the source ofcoarse gravel (e.g. at Budleigh Salterton); flintsform the commonest pebbles and cobbles onbeaches in the south of England.

Many ‘shingle’ (gravel) beaches (such asSlapton Sands in Devon, Chesil Beach in Dorsetand Blakeney Point in Norfolk) have been builtfrom offshore gravels, swept ashore as sea levelrose during the Holocene marine transgression,and former sea-floor sediment has contributedto many beaches elsewhere (see Figure 6.2). Inplaces, flints are derived from erosion of theChalk in which they occur. Indeed, Chalk cliffsare generally associated with flint beachesbecause eroded Chalk debris is quickly brokendown by wave action so that Chalk cobbles forma minor part of the beach material. Most flint inEnglish beaches is secondarily derived fromquite a wide range of intermediate sources.These include the Pebble Beds of the Tertiarysuccession of south-east England, where the‘Pebbles’ are either derived directly from localerosion, or through their incorporation intoriver gravels, such as the sequence of EarlyPleistocene river terraces – attributed in part tothe River Thames – cropping out in Essex,Suffolk and Norfolk. Thus at Dunwich, the cliffcontributes flints from gravels at the top of theexposure that were deposited by the ancientRiver Thames. In contrast, with no local land-ward source, the flints that dominate SlaptonSands must have been brought ashore from anoffshore source. The former river concernedflowed down the English Channel, no doubt fedby such tributaries as the present-day Seine,Rhine and Thames at a time when much of thepresent-day area of the North Sea was occupiedby an ice sheet.

Farther north in England, while we cannotrule out such offshore sources, a large propor-tion of the gravel has been eroded from glacialgravels and till cropping out along the coast or

Table 1.4 General order of resistance to erosion ofBritish rock types (from Clayton and Shamoon,1998).

Very Resistant: Precambrian metamorphosed sedi-ments, Cambrian quartzite and sandstone,Ordovician tuff.

Resistant: Old Red Sandstone, Lower Palaeozoicslates, Palaeozoic basalt and andesite.

High Average: Skiddaw slate, Millstone Grit,Carboniferous limestone, Yoredale series.

Low Average: Palaeozoic shale, Coal Measures,Devonian greywackes, Tertiary basalts.

Weak: Magnesian (Permian) limestone, Jurassic lime-stone, Hastings Beds, Chalk.

Very Weak: Mesozoic and Cainozoic mudrocks,Thanet sand.


10

offshore. In Briton’s Lane Pit, within the CromerRidge of north Norfolk, a 30 m-thick sequence ofcoarse flint gravels demonstrates the power ofthe ice and its associated meltwater in erodingnearby Chalk (for there are few quartzites orother erratics in this section) and so incorporat-ing flints into its deposits. Normally, glacial grav-els and tills include a range of erosion-resistantlithologies alongside flint, notably quartzites(which in part at least have been derived fromTriassic strata) and metamorphic rocks high inquartz content, as well as well-cemented sand-stones perhaps of Carboniferous or Jurassic age.Less chemically stable rocks, such as granitesand limestones, are uncommon as clasts andmay be absent. Thus it is this glacial assemblageof resistant gravel and (quartz) sand that domi-nates beaches along most of the coast north ofthe former glacial limit. Indeed flints arerelatively common even on the Irish Sea coasts,for Chalk crops out on the floor of the Irish Sea,as well as lying beneath the lavas of Antrim.

In Scotland and Wales, by far the greatestsource of gravel and sediment has been derivedfrom glaciogenic sources, deposited both inlandand on the adjacent shelf by either glaciers orglacial meltwater. As a result, the sediments areas varied as the rocks that were originally erod-ed by ice.

In the north and west of Scotland, erosion ofTorridonian sandstones has yielded even oldergravels onto beaches, which also commonly con-tain quartzite, metamorphic schist and gneissclasts in addition to sandstones. In the northernand western isles a wide, nearshore shelf is thesource of biogenic shell sand that has beenswept onto beaches, locally reaching almost100% of the beach materials (e.g. the ‘Coral’beaches at Dunvegan, Skye). In the east ofScotland, igneous- and Old Red Sandstone-derived gravels dominate the extensive beachessourced both from steep-fast flowing rivers andfrom offshore deposits over much of theHolocene Epoch. In south-east Scotland, OldRed Sandstone and Carboniferous sandstonesand shales form the bulk of the beach materialand produce beaches with a high proportion ofquartz sand.

In Wales, sediment and gravel, other than thatof glaciogenic origin, have predominantly beenderived from Lower Palaeozoic and Precambrianshales and slates in the north and west, andmainly Carboniferous limestones in the south.

THE COASTAL MARINEENVIRONMENT: TIDES, WAVES,SURGES AND CURRENTS

K.M. Clayton

In global terms, the British Isles have unusuallyhigh tides and unusually stormy conditions; thusthey have a very dynamic coast, one of the rea-sons why British coastal research has made suchan important contribution to the world litera-ture. However, each of these influences alsovaries greatly around Great Britain. Tidal rangeis highest at the head of inlets such as the BristolChannel, and lowest on the English Channelcoast between Start Point and Portsmouth, onthe East Anglian coast within the North Sea,Cardigan Bay in Wales, and in Shetland inScotland (Figure 1.4). Wave energy is highest oncoasts exposed to the strong winds of westernBritain and the North Atlantic swell; it is lower insuch relatively sheltered areas as the Irish Seaand the North Sea. Given its western exposureto the Atlantic Ocean, the English Channel coasttends to fall into an intermediate category(Figure 1.5).

Both tidal movements and the advance ofwaves into shallow water create currents andthese move sediment in the nearshore zone,shaping sandbanks, which in turn can affect thelocal conditions, for example, by forcing largerwaves to break and so lose energy as they touchbottom on submerged banks, or even to breakagainst them at low tide. In constricted bedrockchannels, perhaps the best example is thePentland Firth, the tides create extremely strongcurrents, and where they are channelledbetween sandbanks as in the Thames estuary oroff Great Yarmouth, the patterns of ebb and flow(often dominating different channels) run muchfaster than in the open sea.

Tidal range has an effect on coastal landforms.Barrier beaches, behind which saltmarshes form,tend to be restricted to areas with relatively lowtidal range, such as the north Norfolk coast.Such areas also have spits, which in some casesgrow to many kilometres in length, for example,Blakeney Point and Orfordness. This is becausewave processes are more efficiently focused on anarrow vertical range and so waves and wave-generated currents assume greater relativeimportance in shaping coastal form in theseareas than tides.

High tidal-ranges can occur towards the head

The coastal marine environment

11

of estuaries (or Firths in Scotland), and here salt-marshes also develop, though compared withareas of low tidal range they are generally steep-er and show much stronger zonation of vegeta-tion, such as in the Bristol Channel–Severn estu-ary. Seawards of the vegetated marsh, wide tidalflats of sand or mud occur. At such sites, notonly are tidal streams more important in deter-mining coastal form, but the relative shelter ofthe estuary also reduces the impact of waves andwave-induced currents in the shaping of marshterraces and creek systems. At intermediate tidalranges, features resulting from both extremescan be found, in places the pattern reflectinglocal exposure to waves or local protection, so

changing the wave energy–tidal range balancefrom one place to another.

It seems unlikely that tidal range can affectcliff evolution, because coastal cliff form is main-ly controlled by the basal removal of materialduring storms, especially those co-inciding withspring tides. However, the height range and per-haps also the slope of shore platforms frontingcliffs will vary with tidal range. Where waveaction is spread over a greater vertical range itwill be less effective at every level than where thetidal range is very small. Thus we would expectwide, and almost level, shore platforms wherethere is a very small tidal range, and moresteeply sloping platforms where the tidal range

4.0

2.5

2.0

4.00

2.00

Figure 1.5 Significant wave height exceeded for 10%of the year (significant wave height is the mean valueof the highest 1/3 of all waves). Wave height is one ofthe manifestations of the quantity of wave energy.(UKDMAP 1998 © NERC.)

6.00 m

5.50 m

5.00 m

4.50 m

4.00 m

3.50 m

3.00 m

2.50 m

1.50 m

2.00 m

1.75 m

1.25 m

1.00 m

0.75 m

0.50 m

0.25 m

N

0 200 km

4.00

6.00

2.50

3.50

2.00

1.75

1.50

1.25

1.000.75

0.50

0.25

0.75

Figure 1.4 Spring tidal amplitude (measured inmetres) around the British coast. Elevations shouldbe doubled to give spring tidal range. (UKDMAP1998, © NERC.)


12

is high (Trenhaile, 1997). In partly enclosed seas, strong winds and

accompanying changes in atmospheric pressurecan produce unusually low or unusually highsea levels, known respectively as ‘negativesurges’ and ‘surges’. Negative surges can bedangerous for large ships that might runaground or lose steering control over sand-banks, but seems to have little morphologicaleffect. Surges can cause serious coastal flood-ing, and also have the effect of allowing waves tobreak with greater force and at higher elevationsat the beach or cliff, often producing the effect ofseveral years of ‘normal’ cliff recession in a sin-gle tide. They can also lead to considerablechanges along low coasts by cutting back dunes,removing sediment from beaches and producingwashover fans where the outer coastal barrier isovertopped. Considerable changes followed thesurge in the North Sea of 31 January–1 February,1953, and severe tidal flooding was caused by anIrish Sea surge at Towyn on the North Walescoast in 1990. On coasts facing the AtlanticOcean ‘extreme waves’ have been reported (e.g.those crossing Loe Bar early in the 20th century)and these may result from tsunamis generatedfar away by submarine earthquakes and by theinteraction of large storm waves with localbathymetry (Hansom, 2001). High-level sandlayers on the east coast of Scotland have beenattributed to tsunamis triggered by the Storeggaslides in the Norwegian Trough, some 7000years ago (Long et al., 1989).

The waves reaching the coast are mainly gen-erated by winds offshore. In the case of thesemi-enclosed seas of the Irish Sea and theNorth Sea, most waves are generated by windsblowing across relatively restricted fetches, andso have a short wave-length, short period, andare relatively steep. Thus along the coasts ofthese seas, the varying pattern of length of fetchis an important control over wave energies fromall directions offshore as well as the frequencywith which winds blow from any one direction.Wave height is proportional to the square root ofthe length of fetch, so that in the North Seawaves from a northerly direction are generallythe largest, with a secondary maximum in EastAnglia for waves from the south-east. In the IrishSea, a west-facing beach like Blackpool,Lancashire, gets its largest waves from a westerlydirection, but these are always short-periodwaves and so put rather small volumes of wateronto the beach as they break. As a result, the

wide, sandy beach at Blackpool generally con-sists of a series of ridges and intervening run-nels; the seaward slopes of the ridges may be inequilibrium with the short-period waves.Locally on the North Sea coast, ridge-and-runnelbeaches are found in the shelter of a headland,limiting waves reaching the beach to those fromthe east or south-east; an example is inBridlington Bay, which is protected from thelarger northerly waves by Flamborough Head,Yorkshire.

On those parts of coast exposed to NorthAtlantic storm and swell waves, energies aremuch higher and the long-period waves putlarge volumes of water onto the beach as theybreak. Thus (as well as providing excellent surf-ing), such wave conditions often produce verywide beaches with a gentle slope, for exampleRhossili in South Wales, the beaches of theWestern Isles and in some of the more exposedCornish bays. Where strong regional windsbuild large waves, energies are very high, but itis also possible for long-period swell generatedfar offshore, even in the South Atlantic, to reachthe western beaches. Such swell loses height asit moves across the ocean, but it can be distin-guished by its typically long period. Beachesexposed to the Atlantic Ocean tend to be domi-nated by the high energies associated with long-period waves, even where the exposure is indi-rect and the waves reach the coast after refrac-tion. But they are also exposed to local stormwaves with much shorter wave-lengths and peri-od, though often steep and rather destructive.In such locations, considerable changes in thebeaches can occur from one storm to another orfrom storm to calmer conditions dominated byswell.

High wave-energies can cause considerableerosion even of resistant rocks, and will exploitstructural weaknesses such as faults, joints andbedding planes. Narrow inlets, caves, stacks andnatural arches are found along our higher-ener-gy coasts even in the most resistant rocks. Goodexamples of such forms, eroded into resistantlithologies, are found almost everywhere on theislands of the St Kilda group and in the ShetlandIslands, such as Foula and Papa Stour. They canalso be found in weaker rocks where wave ener-gies are lower, for example, the Chalk cliffs ofThanet, Kent. Waves are also responsible for thelongshore drift of sediment along the coast andthis is described in the following section.

Coastal sediment supply and sediment cells

13

COASTAL SEDIMENT SUPPLY ANDSEDIMENT CELLS

K.M. Clayton

Some comments on the geological sources ofthe coarser beach sediments have already beenmade above. In many places beach sedimentsare derived updrift from cliffs undergoing ero-sion (the so-called ‘feeder bluffs’). In somecases the only possible source of beach sedimentmay lie offshore, whereas in upland areas a largepart of the coastal sediment supply is erodedinland and delivered down the main rivers.Finally, some lengths of coarse-grained beachsediment (storm beaches) such as Chesil Beachin Dorset, Slapton Sands in Devon, andBlakeney Point in Norfolk must have beenbrought landwards during the Holocene marinetransgression and now represent relict accumu-lations which are no longer being added to.However, finer-grained sediment can still moveonshore, for example, from shoals withinCarmarthen Bay in Wales.

As Bird (1985) has noted in a global review,sediment loss from beaches during the last fewdecades, resulting in decreased width andincreased slope, has been far more commonthan cases where sediment is accumulating andprogradation occurring. The reasons for thisremain uncertain, although a role is played byslowly rising sea level, reduction in offshore sed-iment supply and also by interference with erod-ing cliffs and longshore transport by coastalstructures. The same pattern of beach sedimentloss is documented on the English coast; forexample, careful measurement from 1:10 000maps between Flamborough Head and theThames Estuary showed not only that the lengthof coast being eroded greatly exceeded that atstandstill or prograding, but that along almostall of this coast the low-water mark (LWM) hasreceded more than high-water mark (HWM),which in turn has receded more than the coast-line itself, i.e. the cliff top or the solid line oftenclose to HWST (high-water spring tides) mappedby the Ordnance Survey. Thus the beaches alongthis part of the North Sea coast are steeper andfar less wide than they were a century ago.However, the reasons for this are far from clear,though again sea-level rise, reduction of bothoffshore and fluvial supply and coastal engineer-ing structures must all play an important part.Indeed, in England particularly, the widespread

construction of groynes, revetments and wallshas interfered with coastal sediment movementand the coastal sediment balance.

The alongshore transport of sediment (littoralor longshore drift) is achieved by waves and thecurrents they induce within the breaker zone.The direction is determined largely by the angleof wave approach, i.e. it is related to the domi-nant fetch. Thus the general direction of trans-port is southwards on the eastern coast ofEngland, and eastwards on the Channel coast.

BarraHead

Butt ofLewis

CapeWrath

DuncansbyHead

CairnbulgPoint

Fife NessSt Abb's

Head

FlamboroughHead

The Wash

TheThames

Selsey BillPortland Bill

Land'sEnd

TheSevern

St David'sHead

BardseySound

Great Orme

SolwayFirth

Mull ofGalloway

Mull ofKintyre

9

8

5

6

7

4

3

2

1

1

2

3

4

5

6

7

8

9

10

11

Sub-cell boundary

Major cell boundary

Net drift direction

Variable drift direction

0 100km

N

1011

Figure 1.6 Littoral sediment cells and subcells anddirection of littoral drift. After Motyka and Brampton,1993 and HR Wallingford, 1997. Cells are numbered1 to 7 anticlockwise from St. Abb’s Head for Scotlandand there are three subcells within the Orcadian celland two within the Shetland cell (shown in the inset);clockwise from St Abb’s Head, cells are numbered1–11 for England and Wales.


14

In the northern North Sea, the pattern is west-ward movement along the Moray Firth andmainly southward movement along theAberdeenshire and Angus coast. The patternaround the Irish Sea is a little more complicatedsince it is not open to the north as is the NorthSea, and in general the same direction of trans-port is not maintained for such long distances asalong the Channel and North Sea coasts (Figure1.6). Locally where the coastal alignmentchanges, or shelter is provided by a major head-land, the direction may be reversed. On somecoasts the local direction of movement variesconsiderably from one month to another; this isgenerally where the fetch varies different direc-tions (such as in the Irish Sea) and under theseconditions the direction of longshore transportvaries with the wind direction. But even if thepattern from one month to another is variable,such coasts generally show a consistent long-term pattern of movement, reflecting the domi-nant combination of frequency of wind directionand the length of fetch.

Beaches that are declining in sediment quan-tity, whether caused by sea-level rise, reductionof offshore and fluvial sources or anthropogenicinterference, would normally revert to a dynam-ic equilibrium by allowing more rapid erosion ofthe coastal cliffs, thus improving sediment sup-ply to the local beach system. That this is thenatural pattern is suggested by the response tothe southwards migration of ords (lengths oflow beach volume) along the Holderness coastof England, which is accompanied by a rapid risein the local rate of cliff recession. However,increasingly, such cliffs have been protected bystructures such as revetments and sea walls, sothe sediment supply remains restricted, eventhough beaches are losing sediment downdriftand offshore. This is of course just one aspect ofthe struggle between a natural coastline that willmove in position as an adjustment to, for exam-ple, sea-level rise, and the desire of coastal man-agers to stabilize the position of the coast.

Despite this general understanding of long-shore-transport patterns, the details of directionand rate of transport have only begun to beestablished over the last few decades. Part of theincentive has been the attempt to understandchanging sediment volumes better, as the start-ing point for the improved management of thecoast, whether through built structures or thefeeding of sediment to beaches from offshore.Local studies of sediment transport include the

use of radioactive tracers as at the southern tipof Orfordness and the adjacent Shingle Streetbeach, as well as various less successful attemptsusing dyed or fluorescent sand. More recentlycomputer modelling has been used, involvingthe modelling of the offshore topography andthe generation and refraction of waves based onoffshore wind data iterated over several years.This has allowed estimates of potential long-shore transport, though at many locations this isnot reached due to the shortage of sediment.

In several cases, such work has enabled a sed-iment budget to be quantified, involving the cal-culation of sediment input from cliffs (and itspartition by size into mud, sand and gravel), themodelling of the rate of transport downdrift, themeasurement of the volumes of prograded sedi-ment in zones of accretion and on spits, andthus, as a balancing element, offshore removal,which has been generally very difficult to meas-ure directly (see Figure 5.5). This was achievedrelatively successfully (Clayton et al., 1983) forthe Norfolk cliffs and coast southwards to GreatYarmouth, and fairly consistent estimates havealso been made for the Holderness cliffs, wherethe total volume eroded is higher, though amuch greater proportion is mud.

More recently the drive to understand coastalsediment budgets and their inter-relationshipwith coastal management schemes has led to theadoption of littoral sediment cells and subcellsas the basic units of coastal zone management inGreat Britain (Figure 1.6). The primary cells arelarge scale and the dividing points are the head-lands, such as Cairnbulg Point or FlamboroughHead, around which almost no sediment canpass, or embayments that act as sediment sinks(e.g. the Wash). Within these cells are secondarysubcells; some are short lengths where thecoastal alignment reverses the direction of drfitfor a limited distance, others are where renewedcliff supply restores the dwindling longshoredrift and produces larger beach volumes. Interms of shoreline management plans, the sub-cells are the most important units, but maintain-ing the natural integrity of the primary cells is aconsideration, based on the principle that anyinterference with longshore drift can disadvan-tage beaches – and coastal stability – downdrift.A difficulty in adopting this approach is thatsome cells are already severely disrupted byengineering works, either by coastal defencestructures that have prevented coastal cliffsproviding a continuing supply of sediment to

Sea-level history

15

maintain beaches, or schemes such as the reefsoff of Sea Palling in Norfolk, which haveobstructed the former southerly drift of coastalsediment.

SEA-LEVEL HISTORY

K.M. Clayton

We have a good general understanding of globalsea-level history from the time of the last glacialmaximum, some 18 000 years ago. The abstrac-tion of water from the oceans to build the greatland-based ice caps reduced global sea level tosome 120–140 m below that of the present day.By the beginning of the Holocene Epoch, 10 000years before present (BP), sea level was some40 m below present, and as it continued to rise(the Holocene marine transgression) was within10 m of its present stand at about 5000 yearsago, and close to present level by 4000 years BP(Figures 1.7a,b). However, the precise changesat any one site will depart from this pattern formany reasons, including crustal stability (tecton-ic changes, the effects of loading or removal ofload by ice sheets and the oceans themselves,local sedimentation) and tidal changes as thecoastal configuration has changed, as well asmany other lesser effects that may lead to localdepartures from the general pattern of sea-levelrise. For example, Carter (1982) has shown thatthe post-1950 fall of sea level at Belfast of about1 mm a–1 is probably the result of land-claimaround the estuary, rather than a genuine fall insea level.

Thus local evidence of sea-level history is ofgreat importance, but the complicationsinvolved mean that our knowledge is still veryincomplete and not always well linked to ourunderstanding of the likely causes. Further, werequire both good stratigraphical evidence(including reliable relationship to the sea levelof the time as well as accurate levelling to deter-mine altitude) and good age determination(generally based on radiocarbon, converted tosidereal years) if the local evidence is to be use-ful; so prograding coasts generally have a betterrecord of sea-level history than those undergo-ing erosion. Errors in age determination canresult from inaccurate 14C dates (e.g. the ‘hard-water effect’) or from compaction of sedimentscausing misjudgement of the postulated heightof former sea-level markers.

An independent source of evidence for the

last century or so is the trend of long-term tide-gauge records. The variability of short-term sealevel with changes in the weather and thelonger-term periodicity of spring and neap tidesmeans that records of less than a few decadesare unreliable, or frustrating where tide gaugeshave been discontinued (such as at Felixstowe)or recently established to help in the surge warn-ing system, resulting in data which cannot yetgive a statistically reliable long-term trend.Where gauges have remained in place for manydecades, reliable data indicate that parts ofnorthern Britain are still showing relative rise inland level (and thus relative sea-level fall), aresult of continued recovery from the ice load ofthe last glaciation, while southern Britain gener-ally shows relative sea-level rise, in places fasterthan the average annual rise of sea level (c. 1.5to 2 mma–1) around the coast, indicating at leastlocal land submergence. The result is the wide-ly accepted pattern of relative sea-level fall in thenorth-west and rise in the south, with relativestability along a line just south of the Scottishborder (Figures 1.8a,b). In Scotland, the patternof relative sea-level rise is related to the distancefrom the isostatic uplift centre (see Figure 1.8b),with central Scotland undergoing uplift and sub-sidence characterizing the northern and WesternIsles.

What is less clear is how far neotectonicmovement, other than glacioisostatic recoveryand the effects of water loading following sea-level rise, is of significance. The long-held viewthat Britain is tectonically stable has been chal-lenged in recent years (Embleton, 1993) and sev-eral authors have reported evidence of relativelylocal neotectonic movements (e.g. Clayton andShamoon, 1999; Ringrose et al., 1991), but thesehave generally (though not universally) beeninferred from evidence covering long periodssince Mid- or Late Tertiary times. Thus the ratesof coastal tectonic movement, while highenough to be detectable, are slow comparedwith both the known rates of postglacial isostat-ic recovery and submergence, and with the cur-rent rate of sea-level rise. Thus there is an‘inheritance effect’ that has affected broadcoastal (and near-coastal) form, but the directeffect of neotectonic movements on contempo-rary coastal change is likely to be small. Overtime, further detail will emerge from compari-son of local chronologies of Holocene sea-levelchange, adding to the significance of these stud-ies.


16

Detailed local histories of sea-level changehave been established in several locations wherethe stratigraphical record is good, includingaround Morecambe Bay, the Fens and the northNorfolk coast, and research continues to add fur-ther data to the sea-level history of these sites.From these records it appears that the generalrise of sea level has not always persistedthroughout the mid-late Holocene period, witha sequence of relative transgression succeededby relative regression repeated several times. Anexample of this is the Fenland sea-level curve,which, while showing a general rise over the last7000 years that slowly reduced in rate towardsthe present day, nevertheless includes at leastfour intervals of sea-level fall (Figure 1.7b).Similar regressions are found in other records(e.g. the north Norfolk coast) though it is not

always certain that they co-incide in time. This isnot necessarily to be expected, for the Fenlandarea shows an average rate of subsidence, whenthe sea-level curve is compared with the averageof several North Sea records, of 0.91 m ka–1, andthere are hints that this has varied over time.Further, there is good evidence of a time-lagbetween sea-level tendency and local sedimenta-tion in Fenland, so allowance is needed whencomparisons are made with other areas. Thusthe breaks in the general record of transgressionmay well result from a local combination of sea-level and land-level changes. Attempts havebeen made to separate these two influences, andin time we may expect greater success as thequality of local records improves. For themoment, it would be rash to suggest we have areliable and detailed record of sea-level changes

metr

es

belo

w O

D

0

10

20

10 8 6

Thousands of years before present

Linear subsidence

Eu

stati

c s

ea level

Rela

tive s

ea level

4 2 0

Figure 1.7 Holocene sea-level history: (a) global view; (b) sea-level history in the area around The Wash(Norfolk/Lincolnshire). Three views of the global change in sea level over the last 10 000 years are shown in(a); the smooth curves combine data from different areas, a reconstruction based on a smaller region will showan irregular pattern over time (Shepard, 1963; Bloom, 1978; Mörner, 1972). Because of the local effects ofuplift and subsidence, it is increasingly recognized that such global sea-level curves have the potential to mis-lead and that local relative sea-level curves are generally more secure. The sea-level curve in (b) for the areaaround The Wash is based on an accreting sedimentary sequence preserved in an area that is subsiding at anaverage rate of 0.9 m ka–1. If this subsidence has been at a steady rate, then the local relative sea-level curve(the pecked line) can be converted to a eustatic curve (the solid line) by subtracting the effect of subsidence.(Based on Chorley et al., 1984, and Tooley and Shennan, 1987.)

(a) (b)

Sea-level history

17

over the last few thousand years. Currently, a better understanding is being

acquired of the role of past sea-level change onprograding coasts such as The Wash–Fenland,north Norfolk and the Thames estuary, and this

is concomitant with improvements in our under-standing of coastal evolution. The contrastinghistory of many Scottish prograding coastsundergoing relative sea-level fall over theHolocene Epoch (and in places the delivery of

Figure 1.8a Uplift and subsidence, based on trends in sea level around the coast of Britain. These trends areestablished by comparing local sea-level curves with the eustatic trend shown in Figure 1.7b. Open circles indi-cate that the data were obtained by the author by extrapolation. The vertical scale on the graphs is in metresOD, the horizontal scale is in 103 sidereal years before present. (After Tooley and Shennan, 1987, p.136, fig.4.9.)


18

relatively large volumes of sediment down riversand from offshore) has yet to be compared tosubsiding coasts farther south. Some Scottishcoasts show progradation where large amountsof sediment arrived at a time co-incident with arelative sea-level fall, such as in the Dornoch andMoray firths, but some coasts in the northernand western islands have undergone almost con-tinuous relative sea-level rise. Our knowledge ofthe variation from place to place of relative sea-level rise has yet to be applied to the form anddimensions of shore platforms on coasts under-going erosion, even though this seems likely tobe a factor in the evolution of cliffed coasts.

Our understanding of climate change, includ-ing the evidence for a rise in mean world tem-perature over the past 150 years, is linked to theevidence of contemporary sea-level rise acrossthe world oceans (and matched by the North Seadata) of 1.5 to 2 mm a–1. Climate change mod-els suggest that this rate of rise may increase toat least 4 mm a–1 and perhaps higher, with halfof this rise coming from the expansion of thewarming ocean. Nevertheless, future rates ofsea-level rise may reach or exceed the highestrates experienced during the Holocene Epoch,so greater understanding of past changes mustaid our management of such coasts in the future.

One aspect of future sea-level rise is that asthe coastline is driven landwards (which willusually be the case except where sediment sup-ply can keep pace with the tendency to suchadjustment), the process causes what is current-ly termed ‘coastal squeeze’. That is, the naturalcoastal landform areas from intertidal mudflatsto saltmarshes, beaches and sand dunes will bereduced in width between the low-water markand whatever man-made or natural slopes markthe inland penetration of the highest tides.Unless conditions allow these landward limits tomove (e.g. by the abandonment of flood banks),the zone within which natural coastal landformscan develop will be reduced in width, and thoseforms will be less well developed and no doubtliable to still greater damage in future. The engi-neering adjustment to threatened coastalsqueeze by the removal of artificial structures istermed ‘managed re-alignment’ or ‘managedretreat’ (Hansom et al., 2001).

COASTAL MANAGEMENT ANDCOASTAL ENGINEERING

K.M. Clayton

Over the last two centuries, the land near thecoast has seen many changes in land use. Therecreational use of the coast first led to fashion-able seaside resorts, and with the developmentof the railway network many of these grew intomajor coastal towns devoted to sea bathing andleisure pursuits, with promenades and piers. Atthe same time, the industrial revolution led tothe growth of ports and of seaside industry,while the increasing skill and resources of thecoastal engineer, allowed ever-larger schemes ofland-claim. Saltmarshes, once reclaimed on asmall scale for grazing, were seen as ideal sites

Figure 1.8b Map of isobases of uplift (positive val-ues) and subsidence (negative values) following theLateglacial and Holocene deglaciation of the BritishIsles. The rates shown (in mm a–1) are of crustalmovement in Britain. Isobases cannot be drawn formuch of southern England; point estimates areshown for guidance. (After Shennan, 1989, fig. 9.)

Coastal management and coastal engineering

19

for large-scale industry looking for level land.That local docks could be developed for theimport of raw materials and the export of heavyfinished products was an added advantage. Withthe increased mobility offered by the motor car,seaside villages have expanded into commutingdormitory towns or retirement areas epitomizedby Peacehaven east of Brighton.

The result of this combination of coastalurbanization and the confidence of coastal engi-neers has led to the profound modification ofmuch of our coast (Figure 1.9). Few of the sitesdescribed in this volume, especially those inEngland, are entirely free of coastal structures,though care has been taken to select those thatare least disturbed. Despite the caution of theRoyal Commission on Coastal Erosion andAfforestation, which reported from 1907 to 1911and noted that a balance would need to bestruck between defended coasts and the supplyof sediment from unprotected cliffs, much moreof the coast has been modified throughout the20th century. Events such as the serious flood-ing and loss of life of the 1953 surge on theNorth Sea coast of England encouraged furtherexpenditure on coastal defences.

Conditions changed slightly after 1985 whenall supervision of coastal engineering schemes ata national level in England and Wales was trans-ferred to the then Ministry of Agriculture,Fisheries and Food (formerly the Department ofthe Environment had borne responsibility forupland coasts) and the same cost/benefit testswere applied to defences protecting uplandcoasts as to coastal flood defences, though todate few of the existing structures have beenremoved. However, many are now deterioratingrapidly, and where they protect undevelopedagricultural land it seems unlikely they will bereplaced. In the same way, the modern advicethat planning law should be used to preventdevelopments of land liable to flood, or of coastsliable to undergo erosion, will take many yearsto take effect, though if applied consistently areduction in developed coasts should emerge

Relatively little research has looked at theeffects of engineering works on natural changeat the coast. It seems likely that not only theproduction of sediment from cliffs undergoingerosion has been reduced (Clayton, 1989), butalso the rate of transfer along the coast by long-shore drift has been modified by the large num-ber of groynes along our shores. Indeed, thesegroynes may not only have reduced longshore

transport, but in places seem likely to haveallowed more beach sediment to be moved off-shore and so be permanently lost to the coastalsystem. Sea walls increase wave reflection andoften lead to sediment loss from the beachesfronting them. Land-claim of saltmarshes hasreduced the volume of the tidal prism enteringmany estuaries and may have been a factor in theerosion of the remaining marshes in front of thesea banks (walls) protecting the areas that havebeen reclaimed. We lack full understanding ofthe reasons for the persistent erosion of manysaltmarshes, although in places current schemesfor the set back of the banks and re-establish-ment of saltmarsh may lead to a more generalimprovement in conditions.

The funding of coastal defence works in theUK has concentrated on the initial capital costand not the cost of later repairs. This has made

200kilometres0

N

Figure 1.9 Coastal engineering structures in Britain(‘coastal protection‘ and ‘sea defences’), shown ascoastline with heavier line weight. Note the concen-tration on south-eastern England, Bristol channel,and north Wales and and north-west England. (Datafrom Halcrow Group Ltd for England and Wales, pub-lished with permission from Department forEnvironment, Food and Rural Affairs; Scottish dataafter Ramsey and Brampton, 2000a–f.)


20

it difficult to finance beach nourishment as amethod of coastal defence in the UK. Specialarrangements were made to allow the earlybeach feeds, as at Portobello and Bournemouth,and the recycling of material as at Dungenessand on the eastern side of The Wash atSnettisham. It remains uncommon, although itis increasingly being utilized, for example alongmost of the Lincolnshire coast, and south of theartificial reefs on the Norfolk coast at Waxhamand at Kingston-on-Spey in the Moray Firth.

The recognition that the British coast may bedivided into a series of coastal sediment cells(some of which may have smaller subcells nest-ed within them, see Figure 1.6) is now beingapplied to shoreline management. Under cur-rent arrangements, in England and Wales, a setof Shoreline Management Plans has been drawnup by Local Authorities, or groups of LocalAuthorities (under the auspices of theDepartment of Environment, Food and RuralAffairs), for each coastal sector, the sectors beingbased mainly on the recognized coastal sedi-ment cells. In Scotland, some Local Authoritieshave undertaken similar work for the coastunder their jurisdictions, although it is not a for-mal requirement. The philosophy behind thisapproach is that it is through the understandingand management of coastal sediment volumesthat the greatest stability may be achieved, andthat within a cell, local areas may be allowed toundergo erosion in the knowledge that this willimprove sediment supply, and thus stability, else-where. Where the solution of feeding sand(and/or gravel from offshore) is adopted, thiscan be seen to benefit the whole cell if the feedis in an updrift location, whereas in a few cases(such as at Dungeness and on the eastern side ofthe Wash), sediment is collected downdrift andrecycled updrift to move again through the sys-tem on a cyclical basis.

In England and Wales, the development ofShoreline Management Plans involved a com-plex consultative process led by theEnvironment Agency and utilizing engineeringconsultants. Maritime local authorities and bod-ies such as the Countryside Council for Wales,English Nature, and the Countryside Agencywere involved. These plans are updated at reg-ular intervals; the result is a more organized andlonger-term strategic assessment of needs thanbefore, though inevitably the resulting planstend to require considerable compromisesbetween the widely varying views of the bodies

involved. How far compromises can be made towork on the coast remains to be seen, but it maybe that in future a choice between determina-tion to hold the line, or a willingness to allownatural change in the future, would be betterchoices than some of the compromise proposalscurrently being adopted.

Certainly something of a change in attitudecan be recognized at a national level. Proposalssubject to cost/benefit assessment must nowinclude the ‘non-intervention’ option, and, fac-ing the inevitability of future sea-level rise, theadvantages of ‘managed re-alignment’ are beingcanvassed. Insofar as these changes lead to nofurther encroachments on the length of naturalcoast remaining in Britain they will be welcomedby the geomorphologist.

One aspect of the coast that has receivedgreater attention (especially since the surge of1953) is coastal hazard, both the local threat ofrapid cliff recession, but more widely the threatof coastal surges, both in the North Sea (e.g.1953) and the Irish Sea (e.g. the flooding atTowyn in 1990). It is recognized that water lev-els can be raised during a surge by as much as2.5 m, and with current and future sea-level rise,and perhaps an increase in storm frequency withclimate change, the matter is taken seriously.Well-designed warning systems based on meteo-rological forecasting systems are now in place,and tidal barrages have been constructed, forexample, on the Thames at Woolwich and atHull and Swansea. Education of the public atrisk, however, is less developed.

FURTHER READING

For further information on coastal geomorphol-ogy processes and influences, the reader isdirected to Coastal Systems (Haslett, 2000)Coastal Geomorphology: An Introduction (Bird,2000); An Introduction to CoastalGeomorphology (Pethick, 1984); CoastalEnvironments: an Introduction to the Physical,Ecological and Cultural Systems of Coastlines(Carter, 1988), and Coasts (Hansom, 1988).These titles give a comprehensive treatment ofcoastal evolution and dynamics, providing back-ground for the study of coastal landforms andhow and why they are changing, with world-wide coverage of examples, numerous illustra-tions and extensive references to the scientificliterature. French (1997) provides useful dis-

GCR site selection guidelines

21

cussion of managed re-alignment and coastalzone management and Viles and Spencer (1995)discuss coastal problems.

Steers provides descriptive texts on the coast-lines of England and Wales (1964a) and Scotland(1973).

GCR SITE SELECTION GUIDELINES

V.J. May and N.V. Ellis

The GCR site-selection exercise for coastal geo-morphology followed four categories (‘GCRBlocks’), one for each of England, Scotland andWales and one for ‘Saltmarsh Geomorphology’;although three of the ‘Blocks’ are country based,comparisons were made to ensure that certaintypes of site occurring in each were not over-rep-resented in a Great Britain-wide context.

Before site assessment and selection began,the first stage in the project was to apply theethos of the GCR – outlined below – in order tofine-tune GCR selection-criteria. The coastalgeomorphological literature was reviewed toidentify the most cited sites to assist in the com-pilation of lists of candidate GCR sites. The GCRsite selection work also included a survey of themorphodynamics of the whole coastline, carriedout in conjunction with the CORINE coastal ero-sion project (European Commission, 1998),which provided a means by which to judge the‘representativeness’ (see below) of the short-list-ed sites.

Broad GCR site selection criteria

The general principles guiding GCR site selec-tion are described in the introductory GCR vol-ume (Ellis et al., 1996), but can be encapsulatedin three broad components:

• International geological or geomorphologi-cal importance (for example, internationallyrenowned ‘type’ sites, but other sites thathave informal, but widely held, internationalrecognition are also selected).

• Presence of ‘classic’ or exceptional featuresthat are scientifically important (for exam-ple, ‘textbook’ examples of particular fea-tures or exceptionally unusual or rare typesof features are included).

• Presence of representative Earth science fea-tures that are essential in comprehensivelyportraying Britain’s Earth history. Thus, asite may be selected for showing the mostcomplete regional representation of phe-nomena that are otherwise quite wide-spread.

It should be assumed that an ‘internationally’rated site will also be representative of an eventor process and may include exceptional features.

In order to ensure true national importancein the selected representative sites, site selectionwas underpinned by the premise that the mini-mum number of sites should be selected. Bychoosing only those sites absolutely necessary torepresent the most important aspects of Britain’s

Table 1.5 Morphosedimentological classification of the British coast (based on EuropeanCommission (1998 – the CORINE project érosion cotière).

Morpho-sedimentological type Active (km) Protected* Total (km)(km)

Hard-rock cliffs 7990 7 7997Soft-rock cliffs 1401 221 1622Shingle beaches 818 225 1043Sand beaches 1274 302 1576Heterogeneous beaches 415 126 541Beaches for which no data available 59 0 59Muddy and estuarine coasts 999 484 1483

Totals 12956 1365 14321Anthropogenic coasts (including harbours,

land-claim) 2096

Total 16417

* i.e. modified by coastal defence/protection works.


22

coastal geomorphology unnecessary duplicationwas avoided.

Where several choices of representative sitesexist, a series of weightings was applied to thegeneral guidelines to help to distinguish the best(or most suitable) site for the GCR. For exam-ple, preference was given to sites with the mostextensive or best-preserved record of a certainfeature, the most detailed geochronological evi-dence or a particularly long history of study.Sites that have contributed to our understandingof coastal geomorphology or have significantpotential for future research were also pre-ferred.

In some cases, ‘representative’ sites wereselected for the GCR as part of a group of relat-ed sites. Such a group of sites may show differ-ent aspects of one type of phenomenon, whichshows significant regional variations in its char-acteristics, for example, sites with similar land-forms have been selected from areas having dif-ferent tidal ranges. Wave climates also varygreatly, the greatest contrast being between theNorth Sea and the Atlantic coastline. Within this,wave energies vary enormously, the highestbeing in the Outer Hebrides, west Orkney andShetland. Thus suites of sites can be identifiedin the GCR that demonstrate the differences ofwave climate and tidal range, as well as morelocal variations in wave and tidal conditions. Inthis case there may be ‘core’ sites, perhaps thoseshowing the most extensive and best researchedlandform features, while other sites may demon-strate significant variations on the main theme.Nonetheless, it is the group of sites together thatremains nationally important.

On an entirely practical level, all selected sitesmust be conservable, meaning in essence thatdevelopment planning consents do not exist orthat amendments can be negotiated.

Finally, extensive consultations were carriedout with appropriate geomorphologists, andmany sites were assessed carefully before thefinal listing was produced. The comments madeby the specialists and the field observations wereused to produce a modified site shortlist, andthis was then slightly adjusted duringpreparation of the site descriptions for this vol-ume.

GCR Networks

There are many problems inherent in producinga truly representative list of nationally important

sites that merit conservation. In order to helpprovide a framework for selecting sites, the con-cept of GCR networks has been applied.

The geomorphology of the coastline is con-trolled by a complex interaction of factors – thedynamics of the coastal ‘cell’, geological controls(e.g. rock type and structures), the Pleistoceneinheritance (isostatic and eustatic effects), sedi-ment ‘budget’, tidal regimes as well as anthro-pogenic influence. It is the intention within the‘representativeness’ rationale of the GCR to beable to demonstrate the interplay of thesethemes and their manifestations from the evi-dence present in the selected GCR sites. Thesethemes can be thought of as providing a basis forindividual GCR Networks, which link clusters ofrepresentative sites.

A broad categorization was devised for theEuropean Commission CORINE project érosioncotière (European Commission, 1998), and theclassification scheme is shown in Table 1.5.However, in order to establish a scheme of GCRnetworks for coastal geomorphology, a moredetailed structure was required. Ultimately,some 26 networks (broadly following King,1978) were identified for the GCR project. Thethemes were:

A. Cliffed coasts1. Large-scale structural control: longitudinal

and transverse coasts2. Small-scale structural control: caves, arches,

stacks, geos, zawns3. Cliff forms and processes: plunging cliffs,

slope-over-wall, hog’s back, variety of ratesof cliff retreat, differential erosion

4. Exhumed and emerged forms: cliffs, benches5. Karstic development

B. Shore platforms (including both contem-porary and emerged features)

6. Structurally controlled7. Erosionally dominated

C. Beaches and intertidal sediments8. Beach orientation: relation to wave direc-

tion, swell-dominated beaches9. Beaches undergoing erosion10. Prograding beaches11. Beach phases12. Pre-existing sediment sources, including

pre-existing clasts13. Emerged (‘raised’) beaches14. Cliff-foot beaches

Anthropogenic influences and the GCR

23

15. Dunes: rock-based, gravel-based, restrictedsources, sand plains

16. Spits17. Barrier beaches18. Cuspate forelands and nesses19. Tombolos and tied islands20. Intertidal sediments21. Mudflats, ridge and runnel forms22. Saltmarsh morphology – creeks, saltpans,

piping23. Machair

D. Coastal valleys24. Chines, truncated valleys, coastal waterfalls

E. Inlets and submerged coasts25. Fjords, rias, estuaries

F. Semi-enclosed bays26. Restricted sediment sources and transfers,

submarine barriers, sediment sorting

In England and Wales alone, 186 sites were iden-tified as candidates to represent these themes,each of which was visited and assessed beforebeing reduced to a select 59 GCR sites. ForGreat Britain as a whole, 99 GCR sites wereselected (see Figure 1.2).

Clearly, any one site may be helpful in eluci-dating several of these themes and thereforemay contribute to more than one GCR Network(for example, Culbin, on the Moray Firth, pro-vides information on sea-level change as well asgravel delivery data over the Holocene Epoch ata site characterized by well-developed dunes sit-uated on top of spit structures; Carmarthen Baydemonstrates sea-level change and the geologi-cal controls in cliff development; see Table 1.6).Many sites demonstrate several themes,although some are dominated by a single keyfeature; this has been the basis for the arrange-ment of the chapters in this book. However,sites with particularly diverse assemblages ofcoastal features are grouped together in a finalchapter.

The GCR sites described in this volumeexclude major coastal landslides, such asFolkestone Warren; which are described in theMass Movements volume of the GCR Series(Cooper, in prep.). Cross-reference to thesesites, however, is made in Chapter 2 and thechapter on soft-rock cliffs (Chapter 4). Also,sites that are of interest for coastal features thatare particularly important for elucidating the

Pleistocene history of Britain are described inthe Quaternary volumes of the GCR series (e.g.Campbell and Bowen, 1989, Gordon andSutherland, 1993).

Similarly those sites on the coast that areimportant for their palaeontological, stratigraph-ical, petrological or mineralogical features aredescribed elsewhere in the GCR series.

GCR site boundaries

Definition of the boundary of the sites was basedprimarily upon the extent of the landform suite,but on the more rapidly changing sites, the geo-graphical area in which processes that produceand maintain the landform suite was included asfar as possible. Therefore, on a dynamic coastwith unconsolidated sediment, definition ofboundaries was based initially upon the process-unit – the sediment-transport cell – where thiscan be recognized. However, technically thismeans that many coastal geomorphology GCRsites should extend seawards beyond the low-water mark (LWM), since the sediments and theprocesses are predominantly marine. However,a limitation is that areas below the LWM are notexplicitly covered by the Site of Special ScientificInterest (SSSI) system by which GCR sites areconserved.

On hard-rock cliffs, the landward boundary isusually the level of spray action or of subaerialprocesses such as gullying, but on several sites ithas been set back a few metres from the cliff-topedge. On cliffs undergoing rapid erosion, theboundary has been identified with a probableposition no more than 10 years hence. In thesecases, it will be necessary to adjust the boundaryas cliff retreat continues. The inland boundaryof dune systems is usually the edge of blownsand that has not been reclaimed for farming orforestry. Where dunes have been afforested, thezone over which coastline changes have beendocumented in the 20th century has beenincluded.

ANTHROPOGENIC INFLUENCES ANDTHE GCR


Prior to the GCR project, with the CoastProtection Act (1949) and the east coast floodsof 1953, considerable attention was given to the


24

Tab

le 1

.6M

ain

fea

ture

s o

f ea

ch G

CR

Sit

e, b

road

ly f

ollo

win

g th

e cl

assi

ficat

ion

of

Kin

g, 1

978,

to

sh

ow

wh

ere

diff

eren

t fe

atu

res

are

rep

rese

nte

d.

1. Large-scale structural control

2. Small-scale structural control

3. Cliff forms and processes

4. Exhumed forms: cliffs, benches

5. Karstic development

6. Shore platforms – structural control

7. Shore platforms – erosional control

8. Beach orientation

9. Beach undergoing erosion

10. Prograding beach

11. Beach phases

12. Pre-existing clasts

13. Emerged (‘raised’) beaches

14. Cliff-foot beaches

15. Dunes, including sandplains

16. Spits

17. Barrier beaches

18. Cuspate forelands and nesses

19. Tombolos and tied islands

20. Intertidal sediments

21. Mudflats, ridge and runnel forms

22. Saltmarsh morphology

23. Machair

24. Coastal valleys

25. Inlets and submerged coasts

26. Semi-enclosed bay

C

ha

pte

r 3

H

ard

-ro

ck c

liff

s

1

St

Kil

da A

rch

ipela

go

×

×

×

×

×

2

Vil

lian

s o

f H

am

nav

oe, S

hetl

an

d

×

×

×

×

×

×

3

Pap

a S

tou

r, S

hetl

an

d

×

×

×

×

×

×

×

4

Fo

ula

, S

hetl

an

d

×

×

×

×

×

×

×

×

5

West

Co

ast

of

Ork

ney

×

×

×

×

×

×

×

×

6

Du

ncan

sb

y t

o S

kir

za H

ead

, C

ait

hn

ess

×

×

×

×

×

×

×

×

×

7

Tarb

at

Ness,

Easte

r R

oss

×

×

×

×

×

×

8

Lo

ch

Mad

dy–

So

un

d o

f H

arr

is c

oastl

ine

×

×

×

9

No

rth

ern

Isla

y,

Arg

yll

an

d B

ute

×

×

×

×

×

10

B

ull

ers

of

Bu

ch

an

, A

berd

een

sh

ire

×

×

×

×

×

11

D

un

bar,

East

Lo

thia

n

×

×

×

×

×

×

×

×

12

S

t A

bb

’s H

ead

, B

erw

ick

sh

ire

×

×

×

×

×

×

×

13

T

inta

gel,

Co

rnw

all

×

×

×

×

14

S

ou

th P

em

bro

ke C

liff

s, P

em

bro

kesh

ire

×

×

×

×

15

H

art

lan

d Q

uay,

Dev

on

×

×

×

×

×

×

16

S

olf

ach

, P

em

bro

kesh

ire

×

×

×

×

×

Table of GCR site features

25

C

ha

pte

r 4

S

oft

-ro

ck c

liff

s

17

L

ad

ram

Bay,

Dev

on

×

×

×

×

18

R

ob

in H

oo

d’s

Bay, Y

ork

sh

ire

×

×

×

×

×

×

×

19

B

lue A

nch

or–

Watc

het–

Lil

sto

ck

, S

om

ers

et

×

×

×

×

20

N

ash

Po

int,

Gla

mo

rgan

×

×

×

×

21

L

ym

e R

eg

is t

o G

old

en

Cap

, D

ors

et

×

×

×

×

×

22

S

ou

th-w

est

Isle

of

Wig

ht

×

×

×

×

×

×

×

×

×

23

K

ing

sd

ow

n t

o D

over,

Ken

t

×

×

×

×

×

24

Beach

y H

ead

to

Seafo

rd H

ead

, E

ast

Su

ssex

×

×

×

×

×

×

×

×

×

25

B

all

ard

Do

wn

, D

ors

et

×

×

×

×

×

26

F

lam

bo

rou

gh

Head

, Y

ork

hsir

e

×

×

×

×

×

×

27

Jo

ss B

ay (

Fo

ren

ess P

oin

t), K

en

t

×

×

×

×

28

P

ort

h N

eig

wl,

Gw

yn

ed

d

×

×

×

×

29

H

old

ern

ess, Y

ork

sh

ire

×

×

×

×

×

C

ha

pte

r 6

G

rav

el a

nd

‘sh

ing

le’

bea

ches

30

W

estw

ard

Ho

! C

ob

ble

Beach

, D

ev

on

×

×

×

×

31

L

oe B

ar,

Co

rnw

all

×

×

×

×

×

×

32

S

lap

ton

San

ds, D

ev

on

×

×

×

×

×

33

H

all

san

ds, D

ev

on

×

×

×

×

×

×

34

B

ud

leig

h S

alt

ert

on

Beach

, D

ev

on

×

×

×

×

×

35

C

hesil

Beach

, D

ors

et

×

×

×

×

×

×

×

36

P

orl

ock

, S

om

ers

et

37

H

urs

t C

astl

e S

pit

, H

am

psh

ire

×

×

×

×

×

×

×

38

P

ag

ham

Harb

ou

r, W

est

Su

ssex

×

×

×

×

×

×

39

T

he A

yre

s o

f S

win

iste

r, S

hetl

an

d

×

×

×

×

×

×

40

W

hit

en

ess H

ead

, M

ora

y

×

×

×

×

×

×

×

×

41

Sp

ey

Bay

, M

ora

y

×

×

×

×

×

×

×

×

×

×

42

T

he W

est

Co

ast

of

Ju

ra, A

rgy

ll a

nd

Bu

te

×

×

×

×

×

×

43

B

en

acre

Ness, S

uff

olk

×

×

×

×

×

44

O

rfo

rdn

ess a

nd

Sh

ing

le S

treet,

Su

ffo

lk

×

×

×

×

×

45

R

ye H

arb

ou

r, E

ast

Su

ssex

×

×

×

×

×

×

46

D

un

gen

ess, K

en

t

×

×

×

×

×

×

×

×

×


26

C

ha

pte

r 7

S

an

dy

bea

ches

an

d c

oa

sta

l d

un

es

47

M

ars

den

Bay, C

ou

nty

Du

rham

×

×

×

×

×

×

48

S

ou

th H

av

en

Pen

insu

la, D

ors

et

×

×

×

×

×

49

U

pto

n a

nd

Gw

ith

ian

To

wan

s, C

orn

wall

×

×

×

×

×

×

50

B

rau

nto

n B

urr

ow

s, D

ev

on

×

×

×

×

×

×

×

×

×

×

×

51

O

xw

ich

Bay

, G

lam

org

an

×

×

×

×

52

T

yw

yn

Ab

erf

fraw

, A

ng

lesey

×

×

×

×

×

53

A

insd

ale

, L

an

cash

ire

×

×

×

×

×

×

×

54

L

uce S

an

ds, D

um

frie

s a

nd

Gall

ow

ay

×

×

×

×

×

×

×

×

55

S

an

dw

oo

d B

ay, S

uth

erl

an

d

×

×

×

×

×

×

56

T

orr

isd

ale

Bay

an

d I

nv

ern

av

er,

Su

therl

an

d

×

×

×

×

×

×

×

×

×

×

×

57

D

un

net

Bay

, C

ait

hn

ess

×

×

×

×

×

58

B

alt

a I

sla

nd

, S

hetl

an

d

×

×

×

×

59

S

trath

beg

, A

berd

een

sh

ire

×

×

×

×

×

×

×

60

F

orv

ie, A

berd

een

sh

ire

×

×

×

×

×

×

×

61

B

arr

y L

ink

s,

An

gu

s

×

×

×

×

×

×

×

62

T

en

tsm

uir

, F

ife

×

×

×

×

×

×

×

×

×

C

ha

pte

r 8

S

an

d s

pit

s a

nd

to

mb

olo

s

63

P

wll

-dd

u, G

lam

org

an

×

×

×

×

×

64

Y

nysla

s, C

ere

dig

ion

×

×

×

×

×

×

×

65

E

ast

Head

, W

est

Su

ssex

×

×

×

×

×

×

66

S

pu

rn H

ead

, Y

ork

sh

ire

×

×

×

×

×

×

67

D

aw

lish

Warr

en

, D

ev

on

×

×

×

×

×

×

68

G

ibra

ltar

Po

int,

Lin

co

lnsh

ire

×

×

×

×

×

×

×

×

69

W

aln

ey

Isla

nd

, L

an

cash

ire

×

×

×

×

×

×

×

×

70

W

inte

rto

n N

ess,

No

rfo

lk

×

×

×

×

71

M

orf

a H

arl

ech

, M

eri

on

eth

, G

wy

ned

d

×

×

×

×

×

×

×

×

72

M

orf

a D

yff

ryn

, M

eri

on

eth

, G

wy

ned

d

×

×

×

×

×

×

×

×

×

73

S

t N

inia

n’s

To

mb

olo

, S

hetl

an

d

×

×

×

×

×

×

×

×

1. Large-scale structural control

2. Small-scale structural control

3. Cliff forms and processes

4. Exhumed forms: cliffs, benches

5. Karstic development

6. Shore platforms – structural control

7. Shore platforms – erosional control

8. Beach orientation

9. Beach undergoing erosion

10. Prograding beach

11. Beach phases

12. Pre-existing clasts

13. Emerged (‘raised’) beaches

14. Cliff-foot beaches

15. Dunes, including sandplains

16. Spits

17. Barrier beaches

18. Cuspate forelands and nesses

19. Tombolos and tied islands

20. Intertidal sediments

21. Mudflats, ridge and runnel forms

22. Saltmarsh morphology

23. Machair

24. Coastal valleys

25. Inlets and submerged coasts

26. Semi-enclosed bay

Table of GCR site features

27

74

Is

les o

f S

cil

ly

×

×

×

×

×

×

×

×

×

×

×

75

C

en

tral

San

day

, O

rkn

ey

×

×

×

×

×

×

×

×

×

×

×

C

ha

pte

r 9

M

ach

air

76

M

ach

ir B

ay, Is

lay, A

rgyll

an

d B

ute

×

×

×

×

×

×

77

Eo

lig

arr

y, B

arr

a, W

este

rn I

sle

s

×

×

×

×

×

×

×

×

×

×

78

A

rdiv

ach

er

to S

ton

eyb

rid

ge, S

ou

th U

ist

×

×

×

×

×

×

79

Ho

rnis

h a

nd

Lin

gay S

tran

ds (

GC

R n

am

e:

Mach

air

s R

ob

ach

an

d N

ew

ton

), N

ort

h U

ist

×

×

×

×

×

×

×

×

×

×

×

80

P

ab

bay

, H

arr

is, W

este

rn I

sle

s

×

×

×

×

×

×

81

L

usk

en

tyre

an

d C

orr

an

Seil

eb

ost,

Harr

is

×

×

×

×

×

×

×

×

×

82

M

an

gestr

a, L

ew

is, W

este

rn I

sle

s

×

×

×

83

T

ràig

h n

a B

eri

e, L

ew

is, W

este

rn I

sle

s

×

×

×

×

×

×

84

B

aln

ak

eil

, S

uth

erl

an

d

×

×

×

×

×

×

×

C

ha

pte

r 1

0 S

alt

ma

rsh

es

85

C

ulb

in, M

ora

y

×

×

×

×

×

×

×

×

×

×

×

×

86

M

orr

ich

Mo

re, R

oss a

nd

Cro

mart

y

×

×

×

×

×

×

×

×

×

×

87

S

t O

sy

th M

ars

h, E

ssex

×

×

×

×

×

×

×

×

×

88

D

en

gie

Mars

h, E

ssex

×

×

×

×

×

×

×

×

×

89

K

ey

hav

en

Mars

h, H

urs

t C

astl

e, H

am

psh

ire

×

×

×

×

×

90

S

olw

ay F

irth

(n

ort

h s

ho

re),

Du

mfr

ies a

nd

Gall

ow

ay

×

×

×

×

×

91

So

lway F

irth

: U

pp

er

So

lway f

lats

an

d

mars

hes (

so

uth

sh

ore

), C

um

bri

a

×

×

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28

design of coastal structures and the maintenanceof sea defences. The former Nature Con-servancy Council carried out a large number ofsurveys of beaches and dunes; sites such asChesil Beach, Dawlish Warren and Orfordnessbecame key field sites. In the 1950s, GibraltarPoint became established as a field site undergo-ing regular monitoring, as Scolt Head Island hadsince the 1920s.

Since then, management of the coastline hasbeen an important focus for some coastal geo-morphologists, often in association with coastalecologists, engineers and planners. In particu-lar, between 1969 and 1981, Ritchie and col-leagues in the University of Aberdeen producedfor the then Countryside Commission ofScotland a detailed inventory of all the beaches,sand dunes and machair of Scotland, their geo-morphology and the pressures to which theywere subjected. This work has formed a usefulbenchmark for many of the Scottish GCR sitesdescribed and interpreted in this volume.

It is difficult to ascribe the geomorphologicalconservation value to sites that have been signif-icantly affected by human activities. Very manycoastal sites have been affected directly and indi-rectly by coast protection, tidal defences andreclamation projects, by mineral extraction, orby intensive recreational use. Some remote orotherwise undeveloped sites are used for activi-ties that interfere with access, such as nuclearpower stations or military training areas. SomeGCR coastal geomorphology sites certainlyinclude minor artificial structures, and it is notalways possible to select GCR sites that are‘complete’, ‘natural’ and ‘unspoilt’. But, in gen-eral, sites where interference has been wide-spread have not been included in the GCR.There are two substantial exceptions: SpurnHead and Dungeness, both heavily modifiedmajor landforms. Such sites have been includedin the GCR because the classic importance andlong-history of study of the site argue for inclu-sion; indeed ongoing study of such sites will beimportant if we are to improve our understand-ing of how coasts react to changes broughtabout by human activity.

LEGAL PROTECTION OF THE GCRSITES


The list of GCR sites has been used as a basis for

establishing Earth science Sites of SpecialScientific Interest (SSSIs), protected under theWildlife and Countryside Act 1981 (as amended)by the statutory nature conservation agencies(the Countryside Council for Wales, EnglishNature and Scottish Natural Heritage).

The SSSI designation is the main protectionmeasure in the UK for sites of importance toconservation because of the wildlife theysupport, or because of the geological and geo-morphological features that are found there.About 8% of the total land area of Britain isdesignated as SSSIs. Well over half of the SSSIs,by area, are internationally important for a par-ticular conservation interest and are additionallyprotected through international designationsand agreements.

About one third of the SSSIs have a geologi-cal/geomorphological component that consti-tutes at least part of the ‘special interest’.Although some SSSIs are designated solelybecause of their importance to wildlife conser-vation, there are many others that have bothsuch features and geological/geomorphologicalfeatures of special interest. Furthermore, thereare localities that, regardless of their importanceto wildlife conservation, are conserved as SSSIssolely on account of their importance to geolog-ical or geomorphological studies.

Therefore, many SSSIs are composite, withsite boundaries drawn from a ‘mosaic’ of one ormore GCR sites and wildlife ‘special interest’areas; such SSSIs may be heterogeneous in char-acter, in that different constituent parts may beimportant for different features.

There are, therefore, coastal SSSIs notdescribed in this volume that are important forsaltmarsh, machair, dune and shingle features ashabitat/wildlife sites, regardless of the underly-ing geomorphology. Although such habitattypes are intrinsically linked to the geomorphol-ogy, these other sites were not deemed toachieve the GCR standard for their geomorphol-ogy alone, or they duplicated geomorphologicalfeatures better seen at other sites (The ‘mini-mum number’ criterion of the GCR is an impor-tant factor here (see above)). Therefore, forexample, although only 11 localities aredescribed in this volume for ‘saltmarsh mor-phology’ there are many other SSSIs that havebeen designated because of the habitat/wildlfevalue of their saltmarsh, which will also be ofinterest to the geomorphologist.

Conversely, many of the SSSIs that are

Legal protection of the GCR sites

29

designated solely because of their Earth sciencefeatures have interesting wildlfe and habitat fea-tures, underlining the inextricable links between‘the environment’ and the underlying geologyand geomorphology.

It is clear from the discussion in previous sec-tions that the conservation interest of the geo-morphological features is likely to be affected byshoreline management activities outside the siteitself, especially where the GCR sites lie withinlarger sediment transport cells. However, sinceSSSI notification of GCR sites presently extendsto mean low-water mark in England and Wales,and mean low-water of spring tides in Scotland,there is no statutory protection of the shallowwater sediments that may be the main sedimentsource for beaches.

International measures

Presently, there is no formal international con-servation convention or designation for geologi-

cal/geomorphological sites below the level of the‘World Heritage Convention’ (the ‘Conventionconcerning the Protection of the World Culturaland Natural Heritage’). World Heritage Sites aredeclared by the United Nations Educational,Scientific and Cultural Organisation (UNESCO).The objective of the World Heritage Conventionis the protection of natural and cultural sites ofglobal significance. Many of the British WorldHeritage sites are ‘cultural’ in aspect, but theGiant’s Causeway in Northern Ireland and theDorset and East Devon Coast are inscribedbecause of their importance to the Earth sci-ences as part of the ‘natural heritage’ – theDorset and East Devon site is of particular rele-vance here insofaras it was the outstanding geol-ogy and coastal geomorphology that led to itsinscription. The St Kilda World Heritage site cer-tainly has an important geological componentcontributing to its status.

In contrast to the Earth sciences, there aremany other formal international conventions –

Table 1.7 Coastal Annex I habitats occurring in the UK (from McLeod et al., 2002.)

EU code Habitat name Lay name Priority habitat/ UK specialspecies responsibility

1130 Estuaries Estuaries ×1140 Mudflats and sandflats Intertidal mudflats and sandflats

not covered by seawater at low tide1150 Coastal lagoons Lagoons × ×1160 Large shallow inlets and bays Shallow inlets and bays ×1170 Reefs Reefs ×1210 Annual vegetation of drift lines Annual vegetation of drift lines1220 Perennial vegetation of stony banks Coastal shingle vegetation outside ×

the reach of waves1230 Vegetated sea cliffs of the Atlantic Vegetated sea cliffs ×

and Baltic coasts1310 Salicornia and other annuals colonizing Glasswort and other annuals colonizing

mud and sand mud and sand1320 Spartina swards (Spartinion maritimae) Cord-grass swards1330 Atlantic salt meadows (Glauco- Atlantic salt meadows

Puccinellietalia maritimae)1420 Mediterranean and thermo-Atlantic halo- Mediterranean saltmarsh scrub

philous scrubs (Sarcocornetea fruticosi)2110 Embryonic shifting dunes Shifting dunes2120 Shifting dunes along the shoreline with Shifting dunes with marram

Ammophila arenaria (‘white dunes’)2130 Fixed dunes with herbaceous vegetation Dune grassland × ×

(‘grey dunes’)2140 Decalcified fixed dunes with Empetrum Lime-deficient dune heathland

nigrum with crowberry2150 Atlantic decalcified fixed dunes Coastal dune heathland ×

(Calluno–Ulicetea)2160 Dunes with Hippophae rhamnoides Dunes with sea-buckthorn2170 Dunes with Salix repens ssp. argentea Dunes with creeping willow

(Salicion arenariae)2190 Humid dune slacks Humid dune slacks ×21A0 Machairs Machair ×2250 Coastal dunes with Juniperus spp. Dunes with juniper thickets ×8330 Submerged or partially submerged sea caves Sea caves ×

particularly at a European level – concerning theconservation of wildlife and habitat. Of course,many sites that are formally recognized interna-tionally for their contribution to wildlife conser-vation are underpinned by the geological/ geo-morphological character, but this fact is implicitin such designations. Nevertheless, some of thesites described in the present volume are notonly geomorphological SSSIs, but also habitatsites recognized as being internationally impor-tant. These areas are thus afforded further pro-tection by international designations above theprovisions of the SSSI system. Of especial rele-vance to the present volume are those coastalhabitat types that are dependent on coastal geo-morphology and are conserved as Special Areasof Conservation.

Special Areas of Conservation (SACs)

In 1992 the European Community adoptedCouncil Directive 92/43/EEC on the conserva-tion of natural habitats and of wild fauna andflora, commonly known as the ‘HabitatsDirective’. This is an important piece of supra-national legislation for wildlife conservationunder which a European network of sites –Special Areas of Conservation (SACs) – is select-ed, designated and protected. The aim is to helpconserve the 169 habitat types and 623 speciesidentified in Annexes I and II of the Directive.

Of the Annex I habitat types, 76 are believedto occur in the UK. The habitat types are veryvariable in the range of ecological variation theyencompass. Some are very narrowly defined,comprising a single vegetation type; others arelarge units defined on a physiographic basis,such as Estuaries and Machairs, encompassing

complex mosaics of habitats, and correspondapproximately to the ‘Broad Habitats’ and/or‘Priority Habitats’ of the UK Biodiversity ActionPlan (Jackson, 2000). Although the habitats areidentified for the conservation importance oftheir biological features, individually or collec-tively, many also represent geomorphologicalfeatures, and this relationship is particularlyclear in the list of coastal Annex I habitats (Table1.7). Taken together, these cover virtually thefull range of intertidal sediments, saltmarshes,dunes, shingle structures and sea-cliff habitatswhich occur in the UK.

Where habitats have qualified for selection, aprocess has been applied to ensure that theexamples selected are of high quality and ade-quately represent the feature across its geo-graphical and ecological range in the UK(McLeod et al., 2002).

GCR SITE SELECTION IN CONCLUSION

It is clear from the foregoing that many factorshave been involved in selecting and protectingthe sites proposed for conservation anddescribed in this volume. Sites will rarely fallneatly into one category or another; normallythey have assets and characteristics that satisfy arange of the guidelines and preferential weight-ings. A full appreciation of the reasons for theselection of individual sites cannot be gainedfrom these few paragraphs. The full justificationand arguments behind the selection of particularsites are only explained satisfactorily by the siteaccounts given in subsequent chapters of thepresent volume.


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