An Introduction conservation. to the Geological

G E O L O G I C A L C O N S E RVA T I O NR E V I E W S E R I E S

An Introduction to the Geological Conservation Review

The purpose of this book is to explain the significance of Britain’s Earth heritage — ourinheritance of rocks, soils and landforms — and how the national series of Earth heritagesites was identified in the Geological Conservation Review. It also describes how thesesites are protected by law and explains the practical considerations involved in theirconservation.

This volume is intended primarily for all those with an interest in managing the land:owners and occupiers, managers, planners and those involved in the waste disposal,mineral extraction, construction and coastal engineering industries. It will also be ofinterest to professional and amateur Earth scientists, conservationists, and teachers,lecturers and students of the Earth sciences.

Geological Conservation Review Series 1

The aim of the Geological Conservation Review Series is to provide a public record ofthe features of interest an importance at localities already notified, or being considered fornotification, as ‘Sites of Special Scientific Interest’ (SSSIs). All 42 volumes in the series arewritten to the highest scientific standards and incorporate the cumulative insights ofgenerations of leading Earth scientists, in such a way that the assessment and conservationvalue of the sites is clear. This volume is the introduction to the Series.

The geology of south-west England gives rise to some of Britain’s most spectacular landscape andrich mineral resources, ranging from tin to china clay and building stones. The scientific studyof the rocks in this region has yielded greater understanding of how northern Europe underwenta period of mountain building some 300 million years ago. These immense earth movementswere accompanied by the emplacement into the existing country rocks of vast bodies of moltenigneous rock which cooled to form granite. The photograph shows Haytor Rocks, Dartmoor, anexcellent area in which to examine the textural and compositional variations in the main suiteof Dartmoor granites. This is the reason for the selection of the site as a Geological ConservationReview site. The Dartmoor granite is also renowned for dramatic tor scenery and Haytor iswidely visited as a classic example of such a landscape. Photograph by: S. Campbell

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An Introductionto the

Geological Conservation Review

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JOINT NATURE CONSERVATION COMMITTEE ISBN 1 86107 403 4Peterborough

G E O L O G I C A L C O N S E R VA T I O N

R E V I E W S E R I E S N o . 1

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RReevviieeww

N. V. Ellis (Editor)D. Q. BowenS. Campbell

J. L. KnillA. P. McKirdyC. D. ProsserM. A. VincentR. C. L. Wilson

PPuubblliisshheedd bbyy tthhee JJooiinntt NNaattuurree CCoonnsseerrvvaattiioonn CCoommmmiitttteeeeMMoonnkkssttoonnee HHoouusseeCCiittyy RRooaaddPPeetteerrbboorroouugghhPPEE11 11JJYY

First edition 1996

© 1996 Joint Nature Conservation Committee

ISBN 1 86107 403 4

BBrriittiisshh LLiibbrraarryy CCaattaalloogguuiinngg--iinn--PPuubblliiccaattiioonn DDaattaa

A catalogue record for this book is available from the British Library.

Recommended citation for this volume:Ellis, N.V. (ed.), Bowen, D.Q., Campbell, S., Knill, J.L., McKirdy, A.P., Prosser, C.D.,Vincent, M.A. and Wilson, R.C.L. (1996) An Introduction to the GeologicalConservation Review. GCR Series No. 1, Joint Nature Conservation Committee,Peterborough.

BBrriittiisshh GGeeoollooggiiccaall SSuurrvveeyy ccooppyyrriigghhtt pprrootteecctteedd mmaatteerriiaallss

1. The copyright of materials derived from the British Geological Survey’s work isvested in the Natural Environment Research Council. No part of these materials(geological maps, charts, plans, diagrams, graphs, cross-sections, figures, sketchmaps, tables, photographs) may be reproduced or transmitted in any form or by anymeans, or stored in a retrieval system of any nature, without the written permissionof the copyright holder, in advance.

2. To ensure that copyright infringements do not arise, permission has to beobtained from the copyright owner. In the case of BGS maps this includes bbootthh BBGGSSaanndd OOrrddnnaannccee SSuurrvveeyy. Most BGS geological maps make use of Ordnance Surveytopography (Crown Copyright), and this is acknowledged on BGS maps.Reproduction of Ordnance Survey materials may be independently permitted by thelicences issued by Ordnance Survey to many users. Users who do not have anOrdnance Survey licence to reproduce the topography must make their ownarrangements with the Ordnance Survey, Copyright Branch, Romsey Road,Southampton SO9 4DH (Tel. 01703 792913).

3. Permission to reproduce BGS materials must be sought in writing from Dr JeanAlexander, Copyright Manager, British Geological Survey, Kingsley Dunham Centre,Keyworth, Nottingham NG12 5GG (Tel. 0115 936 3331).

Page layout and design by: R & W Publications (Newmarket) LtdPrinted in Great Britain by: Halstan & Co Limited, Amersham, Buckinghamshire

AACCKKNNOOWWLLEEDDGGEEMMEENNTTSSFFOORREEWWOORRDD

11 TTHHEE SSUUBBJJEECCTT AANNDD PPUURRPPOOSSEE OOFF TTHHIISS VVOOLLUUMMEE

22 TTHHEE NNEEEEDD FFOORR EEAARRTTHH HHEERRIITTAAGGEE CCOONNSSEERRVVAATTIIOONNThe international significance of Earth heritage sitesExceptional Earth heritage sitesEarth science researchEnvironmental forecastingEarth heritage sites in education and trainingThe Earth heritage as a cultural and ecological resource

33 AANN IINNTTRROODDUUCCTTIIOONN TTOO TTHHEE GGEEOOLLOOGGIICCAALL HHIISSTTOORRYY OOFF BBRRIITTAAIINNTThhee iimmppoorrttaannccee ooff ssiitteess

Salisbury Crags and Arthur’s Seat, EdinburghBarton Cliffs, HampshireIslay and Jura, the Inner Hebrides

TThhee ggeeoollooggyy ooff BBrriittaaiinnIntroductionThe origin of rocks

Sedimentary rocksIgneous rocksMetamorphic rocks

Geological timeSome geological patternsMountain building episodes

MMoouunnttaaiinn bbuuiillddiinngg aanndd ppllaattee tteeccttoonniiccssAA ggeeoollooggiiccaall hhiissttoorryy ooff BBrriittaaiinn

The Precambrian rocks of BritainThe Cambrian, Ordovician and Silurian rocks of BritainThe Devonian and Carboniferous rocks of BritainThe Permian and Triassic rocks of BritainThe Jurassic and Cretaceous rocks of BritainThe Tertiary rocks of Britain

Contents

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Quaternary sediments and landforms of BritainBritain after the last ice age

Present-day BritainTThhee iimmppoorrttaannccee ooff BBrriittaaiinn iinn tthhee ddeevveellooppmmeenntt ooff ggeeoollooggyy

44 TTHHEE GGEEOOLLOOGGIICCAALL CCOONNSSEERRVVAATTIIOONN RREEVVIIEEWWPPrriinncciipplleess ooff ssiittee sseelleeccttiioonn

Aims of the Geological Conservation ReviewTThhee ffiirrsstt ccoommppoonneenntt —— iinntteerrnnaattiioonnaall iimmppoorrttaanncceeTThhee sseeccoonndd ccoommppoonneenntt —— eexxcceeppttiioonnaall ffeeaattuurreessTThhee tthhiirrdd ccoommppoonneenntt —— rreepprreesseennttaattiivveenneessssGGeeoollooggiiccaall CCoonnsseerrvvaattiioonn RReevviieeww bblloocckkss

Stratigraphy blocksPalaeontology blocksQuaternary blocksGeomorphology blocksIgneous petrology and structural and metamorphic geology blocksMineralogy blocks

GGeeoollooggiiccaall CCoonnsseerrvvaattiioonn RReevviieeww nneettwwoorrkkssMMaarriinnee PPeerrmmiiaann GGeeoollooggiiccaall CCoonnsseerrvvaattiioonn RReevviieeww BBlloocckk

Durham Province network: the western edge of an inland seaYorkshire Province network

IIggnneeoouuss RRoocckkss ooff SSoouutthh--wweesstt EEnnggllaanndd GGeeoollooggiiccaall CCoonnsseerrvvaattiioonn BBlloocckkPre-orogenic volcanic networkCornubian granite batholith networkPost-orogenic volcanic networkLizard and Start complexes network

PPaallaaeeoozzooiicc PPaallaaeeoobboottaannyy GGeeoollooggiiccaall CCoonnsseerrvvaattiioonn RReevviieeww BBlloocckkSilurian networkDevonian networkLower Carboniferous networkUpper Carboniferous networkPermian network

QQuuaatteerrnnaarryy GGeeoollooggiiccaall CCoonnsseerrvvaattiioonn RReevviieeww nneettwwoorrkkss:: EEnngglliisshhlloowwllaanndd vvaalllleeyy rriivveerrssTThhee CCooaassttaall GGeeoommoorrpphhoollooggyy ooff SSccoottllaanndd GGeeoollooggiiccaall CCoonnsseerrvvaattiioonn RReevviieeww BBlloocckk

Beach complexes of ScotlandBeaches of the Highlands and Islands networks

Beach–dune–machair systemBeach and dune coasts of lowland Scotland networksRock coast geomorphology networksSaltmarsh geomorphology networks

TThhee GGeeoollooggiiccaall CCoonnsseerrvvaattiioonn RReevviieeww ssiittee sseerriieess

55 PPRRAACCTTIICCAALL GGEEOOLLOOGGIICCAALL CCOONNSSEERRVVAATTIIOONN RREEVVIIEEWW SSEELLEECCTTIIOONN MMEETTHHOODDSSSSiittee sseelleeccttiioonn ccrriitteerriiaa

Minimum number and minimum area of sitesMMeetthhooddss aanndd wwoorrkkiinngg pprraaccttiiccee

Site selection procedures within the Geological Conservation ReviewStage 1: Building and briefing the block teamStage 2: Literature review and site shortlisting

Contents

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Stage 3: Field visits and detailed site investigationStage 4: Final assessment and preparation of Geological Conservation Review site documents

The study of the Earth — continuing developments

66 EEAARRTTHH HHEERRIITTAAGGEE CCOONNSSEERRVVAATTIIOONNThreats to the Earth heritage

Quarrying and Earth heritage conservation: threats andbenefits

TThhee hhiissttoorryy ooff EEaarrtthh hheerriittaaggee ccoonnsseerrvvaattiioonn iinn BBrriittaaiinnEEaarrtthh hheerriittaaggee ssiittee pprrootteeccttiioonn

The legal frameworkEEaarrtthh hheerriittaaggee ccoonnsseerrvvaattiioonn iinn pprraaccttiiccee

Conservation strategyClassification of site types

EEaarrtthh hheerriittaaggee ccoonnsseerrvvaattiioonn iinn pprraaccttiiccee —— ssoommee eexxaammpplleessFossil and mineral collecting and conservationCoastal sites

Conservation of the Barton Geological Conservation Review siteActive quarries

Conservation at Shap Granite QuarryDisused quarries

Conservation at Ercall Quarry, ShropshireGeneral considerations at disused quarriesDisused quarries as landfill sites

Cave conservationRoad construction

Conservation of Claverley Road CuttingSite excavation and specimen curation

The excavation in Brighstone Bay, Isle of WightConservation of active geomorphological process sites

Conservation of the River Dee: a mobile meander beltMine dumps

Writhlington Rock Store SSSISite ‘burial’Publicity and public awarenessAdvice on conservation of Earth heritage sites

77 TTHHEE GGEEOOLLOOGGIICCAALL CCOONNSSEERRVVAATTIIOONN RREEVVIIEEWW IINN TTHHEE CCOONNTTEEXXTT OOFF TTHHEE WWIIDDEERR EEAARRTTHH HHEERRIITTAAGGEE CCOONNSSEERRVVAATTIIOONN EEFFFFOORRTTEEaarrtthh hheerriittaaggee ccoonnsseerrvvaattiioonn ssttrraatteeggyyPPrrooggrreessss aanndd ddeevveellooppmmeennttss iinn EEaarrtthh hheerriittaaggee ccoonnsseerrvvaattiioonn

Maintaining the SSSI series through the mechanism of theGeological Conservation ReviewExpanding the RIGS networkDeveloping conservation techniquesImproving documentationIncreasing public awarenessDeveloping international links

EEaarrtthh hheerriittaaggee aanndd nnaattuurree ccoonnsseerrvvaattiioonn

AAPPPPEENNDDIIXXRREEFFEERREENNCCEESS AANNDD FFUURRTTHHEERR RREEAADDIINNGGGGLLOOSSSSAARRYYIINNDDEEXX

Contents

v

The Joint Nature Conservation Committee wishes to acknowledge thecontribution made by the late Chris Stevens. His guidance and enthusiasmprovided a valuable impetus during the early stages of text writing.

Thanks go to those individuals who have written text and made editorialcontributions to this volume: Dr P. H. Banham, Mr J. H. Bratton, Dr K. L. Duff, Dr J. L. Eyers, Dr N. F. Glasser, Dr J. E. Gordon, Dr J. G. Larwood, Dr R. G. Lees,Professor J. McManus, Dr T. Moat, Dr D. P. A. O’Halloran, Dr K. N. Page, Dr L. P. Thomas, Mr D. A. White, Dr W. A. Wimbledon and Ms F. J. Wright.

The help of the consultees to the draft of the volume is gratefully acknowledged.Those who commented are too numerous to mention individually, but theircontributions proved invaluable in the preparation of the final typescript.

Acknowledgements

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In the rocks and landscapes of Britain lies the evidence for ancient events whichfashioned the small but complex part of the Earth’s crust that we now call theBritish Isles. By piecing together this evidence, it is possible to construct the

geological history of Britain. Magnus Magnusson, the Chairman of Scottish NaturalHeritage and one of my colleagues on the Joint Nature Conservation Committee,said that:

‘Our geological past involves a barely believable story of whole continentsmoving around like croutons floating on a bowl of thick soup, of great oceansforming and disappearing like seasonal puddles, of mighty mountains beingthrown up and worn down, of formidable glaciers and ice caps advancingand retreating behind mile-thick walls of ice as they melted and reformedagain. Scotland has been a desert, a tropical rain forest and a desert again; ithas drifted north over the planet with an ever-changing cargo of lizards,dinosaurs, tropical forests, giant redwoods, sharks, bears, lynx, giant elk,wolves and also human beings.

‘There is a fascinating story to tell that is of profound relevance to the world.’

What Magnus Magnusson said about the geological history of Scotland is alsotrue for Britain as a whole. There is indeed a fascinating story to tell, although

some of the chapters are still far from complete. For the full story to unfold it is vitalthat the important rocks and landforms of Britain must be protected so that they canprovide the necessary scientific resource for future work. And this may well utilisenew scientific techniques yet to be discovered.

Britain was the cradle of modern geology, and observations made by Britishgeologists in the eighteenth and nineteenth centuries laid the foundations of thescience as we know it today. Many of the sites at which these observations weremade continue to be conserved as a part of our national Earth heritage. Thecontribution that the geology of Britain has made to international science is asimportant today as it has ever been. British sites are world-renowned for providingthe milestones that mark geological time and the benchmarks that define geologicalprinciples. There is every reason for us to take a special pride in this unrivalledEarth heritage.

Foreword

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Since the heady, pioneering days in the early development of the Earth sciences,the study of the geology of Britain has continued to provide evidence to construct,and then test, theories about the development of the Earth and the processes thattake place within its interior and on its surface. Geology today is as much about thefuture as it is about the past. By learning about past climates we can understand ourpresent climate system better and thus how to evaluate the impact of future climaticchanges.

The geology of Britain has contributed to our national wealth and so influencedour archaeological and industrial inheritance, from the Phoenicians trading forCornish tin, to the coal and iron which created the Industrial Revolution and, now,to the oil and gas below our coastal seas which is essential to our economic well-being. The geologists of tomorrow, who will discover new economic resources andlocate sites for new engineering works all over the world, are being trained in anenvironment of extraordinary geological quality.

Natural landforms create the environments within which the diverse flora andfauna of Britain live. Rocks provide the soil and influence the drainage conditionsof biological habitats. Biological and geological forms and functions are inextricablylinked to create a series of natural systems of immense richness and diversity.

Active conservation measures are required to protect the geology and landformsof Britain as an important and irreplaceable scientific, educational, cultural,aesthetic and potentially economic resource. If irreparable damage or loss was tooccur then it is our own society that would be impoverished.

Conservation of geological and geomorphological sites has always been part ofthe responsibilities of the statutory nature conservation agencies. A major initiativeto identify and describe the most important geological sites in Britain began in 1977,with the launching of the Geological Conservation Review. This book provides adescription of the methods and practice of the Review, as well as a backgroundaccount of the geological history of Britain which demonstrates clearly why theEarth heritage of this country is so important.

I am confident that this book will be an invaluable reference for those who wishto understand the Geological Conservation Review and for those who need tomanage our extraordinarily diverse Earth heritage.

The Earl of Selborne KBE FRSChairman, Joint Nature Conservation Committee

Foreword

viii

An artist’s impression of the Earth from space, as it might have appeared some 360million years ago. The outline of present-day Britain is shown as a dotted line.Reproduced from F. W. Dunning et al. (1978) by permission of the Natural HistoryMuseum, London.

The subject and purpose of this volume

Chapter 1

The purpose of this book is to explainwhy Britain’s Earth heritage isimportant and how the national series

of Earth heritage sites was identified in theGeological Conservation Review. It alsodescribes how these sites are protected bylaw and how they are conserved.

This volume is intended primarily for allthose with an interest in managing the land:owners and occupiers, managers, plannersand those involved in the waste disposal,mineral extraction, construction and coastalengineering industries. It will also be ofinterest to professional and amateur Earthscientists, conservationists, and teachers,lecturers and students of the Earth sciences.

The geological history of Britain is fascinating.Since the cooling of the outer part of theEarth and the formation of the oceans,

whole continents have moved around the planet,repeatedly coalescing into great land masses andfragmenting again. When continents collided,great mountain ranges, including the Alps andHimalayas of today, were formed and then erodedaway. The rocks of Britain record a diversity ofenvironmental conditions that unfolded overthousands of millions of years. For some of thetime ‘Britain’ was located in the tropics. As itdrifted northwards, great sandy deserts werereplaced by equatorial forests and swamps only, indue course, to become desert once more. Shallowseas between land masses became isolated fromtheir neighbouring oceans and dwindled away.Quiet landscapes were disrupted by eruptingvolcanoes, lava fields cooled, vents solidified andthe volcanoes passed into history. In more recentages, ‘Britain’ drifted into temperate latitudes.Glaciers and ice caps have repeatedly advancedand retreated over its surface, moulding andshaping the landscape. Even today, the appearanceof the land continues to change; sand dunes shift,coastlines and river valleys evolve, rock weathersand landslips alter the shape of the countryside.

Just as the land and seas have changed over theages, so have the life-forms they supported. Lifeevolved in the oceans in the form of unicellularmarine organisms which helped to change thecomposition of the atmosphere. They eventuallyevolved into many types of multi-cellularorganisms such as coral, predatory sea-scorpions,ichthyosaurs and countless other invertebrates and

vertebrates. Plants, and then animals, colonisedthe land. Forests came and went; giant horsetails,tree ferns, redwoods and magnolias successivelydominated the landscape of their time. After theland plants came insects, amphibians, dinosaursand other reptiles, birds, mammals and, eventually,human beings.

For over two hundred years, natural historiansand scientists have been piecing together theevidence for the geological history of Britain.Careful observation and interpretation of the rocksin natural and man-made exposures, and thefeatures of the landscape, have provided both theinspiration and the information needed to establishthis history. But the picture is still far fromcomplete, there are areas of uncertainty andcontroversy, and much remains to be done.


3

FFiigguurree 11.. Haytor Rocks, Dartmoor, is not only animportant part of Britain’s natural heritage for itsaesthetic quality, but also for the Earth sciences.Study of the granite rock here has revealed importantinformation about the cooling and crystallisation ofmolten rock. The rocks form an impressive ‘tor’,formed by weathering. Photo: S. Campbell.

The legacy of the geological past — rocks, soilsand landforms — comprises the EEaarrtthh hheerriittaaggee of Britain (Figure 1). Much of this heritageis hidden beneath the land surface, but coastalcliffs, river gorges, cliffs, mountain crags, quarries,and road and railway cuttings provideopportunities for study. Just as some activitiessuch as quarrying and road building have createdmany rock exposures, they can also destroy orobscure them. Coastal cliffs have been protectedto prevent erosion, disused quarries and railwaycuttings have been used as tipping sites, fossil-bearing rocks have been dug up and sold for profit,and sand and gravel have been extracted foraggregate. Much of this activity has to take placein a country where land has to serve manypurposes. If they are uncontrolled, these activitiesmay ultimately lead to the loss of the mostimportant elements of our Earth heritage. It is

necessary to identify the key sites and to safeguardtheir future.

The identification of the most important Earthheritage sites in Britain began 50 years ago. In1977, the Nature Conservancy Council began asystematic review of the key Earth sciencelocalities. This was designed to identify, and helpconserve, those sites of national and internationalimportance in Britain. This review, known as theGeological Conservation Review, was completedin 1990, and is an international first. No othercountry has attempted such a systematic andcomprehensive review of its Earth heritage.

The results of the Geological ConservationReview are being published in 42 volumes writtenfor a specialist scientific readership. Thisintroduction to the series is written for a wideraudience and includes a glossary and list ofsuggestions for further reading.


4

The need for Earth heritage conservation

Chapter 2

Many people are aware of the need for theconservation of the natural world.Reports about pollution, disappearing

rain forests and the extinction of species haveincreased our perception of the need to protectthe natural environment. Rocks, minerals, fossils,soils and landforms are an integral part of ournatural world. The distribution of habitats, plantsand animals depends not only upon climate, butalso upon the geology and landscape.

As well as being a fundamental part of the naturalworld, geology and landscape have had a profoundinfluence on society and civilisation. Our use of theland, for agriculture, forestry, mining, quarrying andfor building homes and cities is intimately related tothe underlying rocks, soils and landforms. Moreover,economic resources such as coal, oil, gas and metalores have played an important role in the industrialdevelopment of Britain, particularly during theIndustrial Revolution.

The heritage value of sites and the importance ofconserving them can be summarised under sixthemes:

❏ the international significance of Earth heritage sites

❏ exceptional Earth heritage sites ❏ Earth science research❏ environmental forecasting ❏ Earth heritage sites in education and training❏ Earth heritage as a cultural and ecological

resource.

THE INTERNATIONAL SIGNIFICANCEOF EARTH HERITAGE SITES

Much of the early knowledge of the historyof the Earth was developed in Britain(see Chapter 3), and many British sites

have played a part in the development of nowuniversally applied principles of geology. Thesesites have great historical importance. Forexample, many of the names of periods ofgeological time are derived from Britain. Manyother sites serve as international referencesections. By reference to these international‘standards’ (Figure 2), the relative ages of rocks allover the world can be compared. Otherinternationally important British reference sitesinclude those where rocks, minerals and fossilswere first described. Such sites must be conservedso that they can continue to be used as thestandard references.

EXCEPTIONAL EARTH HERITAGESITES

There are many sites in Britain which are ofinternational importance because of theirexceptional nature. For example, rocks

from Charnwood in Leicestershire (Figure 3) haveyielded some of the oldest multi-celled animalfossils in the world. Similarly, a site at Rhynie inScotland (see Figure 46) contains some of theoldest known fossils of higher plants, insects,arachnids (mites and spiders) and crustaceans.They occur in an exceptionally well-preservedstate; so much so, that the microscopic detail and

Exceptional Earth heritage sites

7

FFiigguurree 22.. Dob’s Linn, south-west Scotland. Thisinternationally important site is officially recognisedby the International Union of Geological Sciences(IUGS) as the reference section for the boundarybetween the Ordovician and Silurian Periods (seeFigure 13). This boundary is used as the globalstandard for comparative purposes. For example,fossils and other rock attributes that occur at Dob’sLinn can be compared with those in rocks elsewhere.Photo: C. C. J. MacFadyen.

cell structures of the original organisms can bestudied. Such sites are rare and are an irreplaceablepart of the Earth heritage of the world.

EARTH SCIENCE RESEARCH

The geology of Britain provides a resource forresearch (Figure 4). Natural rock outcropsand landforms, and artificial exposures of rock

created in the course of mining, quarrying andengineering works, are crucial to our understandingof Britain’s Earth heritage. Future research may helpto resolve current geological problems, support newtheories and develop innovative techniques or ideasonly if sites are available for future study.

ENVIRONMENTAL FORECASTING

Understanding how processes have operatedin the past — the climate system, soilformation, desertification and the evolution

and extinction of plants and animals — contributesto our comprehension of the problems of the

present. We may be able to use this knowledge toforecast volcanic activity, earthquakes or changes inclimate. For example, by studying the dynamics ofnatural systems, such as rivers and coasts, it may bepossible to predict how land and coastal processeswill operate in the future. This will aid floodprediction and management, the mapping ofphysically hazardous areas and coastal management.

Evidence from the sediments and landforms,


FFiigguurree 33.. The rocks of theMemorial Crags at BradgatePark, Charnwood Forest,Leicestershire andreconstruction of Charniamasoni, a primitive life-form.The rocks exposed in the cragsare probably 650 –700 millionyears old.

Occasionally, the rocksurfaces show impressions ofsome of the first forms of life— imprints of soft bodies ofsome of the earliest largemulti-celled organisms. Theseinclude the remains of jelly-fish and sea-pen-likeanimals, including Charnia masoni.

The preservation of soft-bodied animals is rarebecause they usually decay very soon after death or areeaten by scavengers. In this case, the animals wereprobably engulfed by a catastrophic event, perhaps themass slumping of sediment, which trapped the fauna.The animals became preserved in the sediment, whicheventually became rock. Because of the worldwiderarity of the preservation of these early life-forms,Bradgate Park is of great importance to the study ofearly life. Photo qLeicestershire Museums.

8

particularly over the past 15,000 years, shows thatthe natural environment is highly sensitive toclimatic change. Further study will throw light onpossible future changes in the climate system andthe faunal, floral and environmental responses tosuch changes (Figure 5).

As well as recording natural changes, thesediments in lakes and bogs provide records of theeffects of human activities on the environmentthrough pollution, vegetation changes (includingforest clearance) and soil erosion. These recordsare important for assessing the effects of currenthuman activity.

EARTH HERITAGE SITES INEDUCATION AND TRAINING

Earth heritage sites are essential for trainingand education. Students and teachers needsites for practical demonstration of the

principles of geology and to illustrate theprocesses of landscape evolution (Figure 6a).

The use of rocks and minerals, water and theenergy derived from fossil and nuclear fuels, are atthe centre of modern society and are essential toits economic well-being. Trained geologists areneeded to locate and extract oil and gas (Figure6b), metal ores and the raw materials for theconstruction industry, such as clays for brick-making, stone for building and aggregates forconcrete. Geologists also discover aquifers, andlocate reservoirs and sites for major engineeringprojects.

Earth heritage sites in education and training

9

FFiigguurree 44.. Moel Tryfan, Gwynedd. This is a historicallyimportant site, 400 metres above sea level, that consistsof sand and gravel containing fossils of sea-shells. Itwas cited as evidence for the biblical flood by theDiluvialists. Subsequently it was interpreted as aglacial deposit carried from the sea bed by an Irish Seaice sheet during the last ice age, about 23,000 yearsago. This has a bearing on the dimensions of the lastIrish Sea ice sheet, the extent to which it may havedepressed the Earth’s crust, and the degree of crustal‘rebound’ after glaciation (see also Figure 10). It is asubject of ongoing research. Photo: S. Campbell.

FFiigguurree 55.. Traeth Mawr, Brecon Beacons. This site hasa sequence of peat and clay deposits which contain apollen record reflecting marked fluctuations in climatefrom 14,000 years ago to the present. It providesinformation about the nature and rate of climatic andenvironmental changes. The photograph shows ageneral view of the site. Photo: S. Campbell.

THE EARTH HERITAGE AS A CULTURALAND ECOLOGICAL RESOURCE

Geological features contribute to the aestheticand ecological quality of landscape as part ofthe cultural heritage of Britain (Figure 7).

Geology trails, visitor centres, museums, show cavesand mines open to the public, enhance and deepenour appreciation of the Earth heritage. Some placesattract hundreds of thousands of visitors each year.


FFiigguurree 66.. Kimmeridge Bay, Dorset.((aa)) The site is an importantlocation for training courses,universities, schools andgeological societies. Thephotograph shows members of theDorset Geologists’ AssociationGroup visiting the site whichdisplays organic-rich rocks similarto those that have generated oiland gas under the North Sea.Photo: R. Hannock, DorsetGeologists’ Association Group. ((bb)) Oil was discovered atKimmeridge in 1956. Since then,the wellsite has continued toproduce 100 barrels of oil a day.Photograph copyright SillsonPhotography/BP Exploration Ltd.Reproduced with kind permission.

10

FFiigguurree 77.. Geology is an inseparable part of the naturalworld. The photograph shows an area of limestonepavement at Scar Close National Nature Reserve inNorth Yorkshire. Water has percolated through joints inthe exposed limestone and produced deep clefts (grykes).In the sheltered grykes, unusual plant life, includingmany rare ferns and orchids, has developed. The micro-climate in the grykes is more like that of woodland thanexposed hillside. Photo: P. Wakely.

aa

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An introduction to thegeological history of Britain

Chapter 3

THE IMPORTANCE OFSITES

In the previous chapter, a varietyof sites were introduced toillustrate the need for Earth

heritage conservation. Evidencefrom many sites, where rocks andlandforms were formed at differenttimes and places, has allowed ahistorical sequence of geologicalevents and previous geographies tobe built up. These rocks andlandforms at Earth heritage sites arestill important for revealing newevidence, and for refining theoriesconcerning their method and date offormation. To illustrate theimportance of sites to the Earthsciences, three are described whichshow how information about Earthhistory can be inferred from theevidence they contain.

Salisbury Crags andArthur’s Seat, Edinburgh

Research began at this site overtwo centuries ago and theCrags played a most significant

role in the early establishment ofgeological science. In Theory of theEarth (1795) James Huttonadvocated the Vulcanist theory thatthe crystalline rocks of SalisburyCrags were formed by the intrusionand cooling of hot molten rock(magma) and not, as was the contemporaryNeptunist view, as a precipitate from a primordialsea. Study and interpretation of the site wastherefore vital in deciding the controversy betweenVulcanists and Neptunists.

The igneous rock is sandwiched withinsedimentary rocks which were baked as themolten rock intruded (Figure 8). Much of theoverlying sedimentary rock has been removed byerosion and quarrying. An igneous rock mass,such as that at Salisbury Crags, which lies parallelto the beds is called a sill (see Figure 12).

The principle that processes observed todaycan be used to interpret those which occurred inthe past is an important tool in Earth science. Bymaking comparisons with contemporary active

volcanoes and volcanic rocks, it is possible to findevidence in the Edinburgh area of former lavalakes, volcanic vents (now preserved as lava blocksin volcanic ash), numerous lava flows, volcanic ashlayers and a sequence of lake sediments whichaccumulated within and adjacent to the volcanicvents. Arthur’s Seat consists of two pipes of anancient volcano which were active 350 millionyears ago. The site also shows the effects of earthmovement, which has caused the eastward tilt ofthe rocks. The relationship between the originalvolcano and Arthur’s Seat is shown in Figure 8.

The site is now one of the most heavily usededucational areas in Britain, and is of internationalsignificance as one of the most intensivelyinvestigated ancient volcanoes in the world.

The importance of sites

13

FFiigguurree 88.. Salisbury Crags and Arthur’s Seat, Edinburgh. Thediagram shows the relationship between the geology and the ancientvolcano. Photograph reproduced by permission of the Director,British Geological Survey. NERC copyright reserved. Diagram afterWilson (1994).

Barton Cliffs, Hampshire

These cliffs (Figure 9) are internationallyknown for the rich and diverse fossilassemblage that they have yielded. These

fossils and the sediments in which they arecontained provide evidence for their contemporaryenvironments. Comparisons with present-dayenvironments assist this process further.

The abundant fossils at Barton Cliffs —molluscs, reptiles, mammals, birds and plants —have also enabled correlations to be made withrocks of similar age in other parts of the world.Thus the exposures at Barton are an internationalreference section or ‘stratotype’, and sediments allover the world of an equivalent age are calledBartonian, which corresponds to a span of timebetween 41 and 35 million years ago.

Islay and Jura, the Inner Hebrides

Raised cliff-lines, shore-platforms and shinglebeach ridges, up to 30 metres above presentsea level, occur along the coastlines of Islay

and Jura in the Inner Hebrides (Figure 10). Theyprovide evidence about changes in the relativelevels of land and sea during the late-glacial period,at the end of the last ice age.

During an ice age, large volumes of ocean waterbecome locked up in ice sheets and glaciers and, inconsequence, the global sea level falls. In thoseareas actually covered by ice, such as Scotland, theweight of ice depresses the Earth’s crust below theposition of the modern sea level. At the end of anice age, water is returned to the oceans by meltingice sheets and the global sea level rises. In the

glaciated areas, the Earth’s crust recovers, orrebounds, as the weight of the ice is removed. It is acomplex process because three factors are involved:the ice itself is in retreat and allows the rising sealevel to flood the depressed crust, and the Earth’scrust is also recovering. These processes occurredat variable rates. But when the rate of sea-level riseand the rate of crustal recovery were approximatelythe same, major shoreline features were fashioned.This happened at ocean levels below that of modernsea level. After the ice age, when the Earth’s majorice sheets had melted, when sea level had beenrestored to its modern position and the Earth’s crusthad recovered to its pre-glacial position, the late-glacial shorelines were uplifted above modern sealevel.

The late-glacial coastal features of Islay and Jurawere formed when global sea level was below thepresent, and when the Earth’s crust was locallydepressed by the weight of the Scottish ice sheet.Both the global sea level and the Earth’s crust of theInner Hebrides have now recovered to their pre-glacial position. The coastal features that wereformed between approximately 15,000 and 12,000years ago, below the modern sea level, have beenuplifted and now lie up to 30 metres above sea level.

THE GEOLOGY OF BRITAIN

Introduction

Geological maps provide the framework intime and space which permits stories fromindividual sites to be synthesised to

An introduction to the geological history of Britain

14

FFiigguurree 99.. Cliffs near Barton-on-Sea, Hampshire. The cliffsare made up of sedimentsdeposited in marine, brackishand freshwater environments.Where these sediments occurinland, there are no naturaloutcrops, the land largelybeing built over or farmed,and there are fewopportunities to see verticalsections through the strata.On the coast, however, freshsections occur as the seaerodes the cliffs, but they canbe obscured by coastal defenceworks and landslides. Photo:C. D. Prosser.

produce the geological history of Britain. Figure11 is a simplified map showing the distribution ofrocks across the British Isles. It does not showsands, gravels and other sediments depositedrecently by rivers, or those left behind during theice ages. Exploring this map and its key providesan insight into the immensity of geological time,and the origins of the great variety of rocks foundover such a relatively small area of the planet.

The origin of rocks

The key to Figure 11 is divided into threesections, reflecting the division of rocks intothree major groups according to the way in

which they were formed: sedimentary, igneousand metamorphic.

Sedimentary rocks

Weathering and erosion of pre-existingrocks at the Earth’s surface yields a vastamount of rock debris that is

subsequently transported by rivers and marinecurrents to produce sediments such as sands andmuds. After burial beneath further layers ofsediment, these deposits become consolidated toproduce sedimentary rocks such as sandstones,mudstones and shales. In addition to being formedfrom fragments of pre-existing rock, sedimentaryrocks such as limestones are produced byaccumulation of the calcareous skeletons oforganisms, for example corals or bivalve shells(like those commonly seen on British beaches).For example, the accumulation of the microscopiccalcareous skeletal elements of plankton producesa very fine-grained limestone known as chalk.

Igneous rocks

Rocks that have crystallised from moltenmaterial (magma) consist of individualinterlocking angular mineral grains, unlike

sedimentary rocks, in which the mineral grains orrock fragments show some degree of rounding.

Igneous rocks

15

FFiigguurree 1100.. The coasts of the islands of Islay and Jura in the Inner Hebrides display raised ice-age shorelines,especially spectacular shingle beach ridges. At one locality, up to 31 unvegetated shingle ridges occur up to 30metres above present sea level. These were formed at the end of the last ice age, when sea level and the level ofthe Earth’s crust in the Inner Hebrides were below modern sea level. These late-glacial shorelines and shingleridges were uplifted to their present position when the Earth’s crust recovered from the load of the ice sheet. Photo: J. E. Gordon.


16

FFiigguurree 1111.. Geological map of Britain and Ireland. Each period, although represented on the map by a singlecolour, may include a variety of rock types. For example, the Silurian (pale mauve) includes shales andmudstones, and the Jurassic (olive-green) includes limestones and clays. This simplification is necessary to beable to show the geology of Britain on such a small map. See glossary for definition of terms. Reproduced bypermission of the Director, British Geological Survey. NERC copyright reserved.

Igneous rocks may have cooled at the Earth’ssurface, in which case they are called extrusive (orvolcanic, as in the key to Figure 11), or beneath theEarth’s surface as intrusive rocks (Figure 12).Granite, granodiorite, gabbros and doleritereferred to in the key to Figure 11 are all examplesof intrusive rocks, whereas basalt, andesite andrhyolite are extrusive.

Metamorphic rocks

Rocks which have been altered from theiroriginal state by heat and/or pressure areknown as metamorphic rocks. Such

alteration occurs from several to tens of kilometresbeneath the Earth’s surface. Slates are grainedmetamorphic rocks formed from mudstones, andare included under sedimentary rocks in the key toFigure 11. Schists and gneisses are coarsercrystalline metamorphic rocks which formed deepwithin mountain belts.

Geological time

The key to the geological map shown in Figure11 subdivides sedimentary rocks intoCenozoic, Mesozoic, Palaeozoic and Upper

Proterozoic. These terms correspond to particularspans of time (the numbers to the right of the key toFigure 11 are ages in millions of years). The firstthree are called eras of geological time and togetherconstitute the Phanerozoic Eon, which ischaracterised by rocks containing fossils of animalswith mineralised skeletons. The term ‘Phanerozoic’was originally coined from the Greek words for‘evident’ and ‘life’. The time before the PhanerozoicEon is divided into two other eons, the Proterozoicand the Archaean, which together are often calledthe Precambrian. The term ‘Upper Proterozoic’ onthe map refers to the most recent part of theProterozoic Eon. The eras of the Phanerozoic arethemselves divided into periods whose names aregiven in bold type next to the colour key (e.g.Permian, Cambrian). So for the sedimentary rocks,each colour represents rocks formed during aparticular period.

Eons, eras and periods are shown systematicallyin Figure 13 as time divisions of the stratigraphiccolumn. The column is arranged in chronologicalorder with the oldest period at the bottom and theyoungest at the top, just as sedimentary rocks ofthese ages would be stacked now if they had beenleft undisturbed since they were laid down.

As stated in Chapter 1, Britain was the cradle of

the science of geology, resulting in many of thedivisions of geological time shown in Figure 13being named here by pioneering geologists, asshown in Table 1. These geologists realised thatsediments deposited during a particular period ofgeological time are characterised by distinctiveassemblages of fossils (see information box on page19) which enable rock successions of the samerelative age to be identified in many parts of theworld. It may seem surprising that geologists do notuse dates in the same way as historians. There aretwo main reasons. First, the periods within each ofthe eras were recognised by early geologists beforethere was any agreement about the age of the Earth,or the duration of the periods. The advent ofmethods of dating rocks using the small amounts ofradioactive elements present in them enabled therelative scale represented by the periods to becalibrated in millions of years. But even today, thissubdivision is not precise because of experimentalerrors and the different versions of such calibrationsin use. This is the second reason that the names ofthe geological periods are used rather than dates —because it is less confusing than using numbers.

Geological time

17

FFiigguurree 1122.. The principal occurrence of igneous rocks.Extrusive: lava flows; Intrusive: sills, dykes andplutons. Molten rock erupting from volcanoes mayalso produce ash (referred to as tuff in the key toFigure 11). After Wilson (1994).

1 JanuaryOne minutepast midnightBirth of the Earth

Mid-FebruaryEarliest single-celled life

21 MayOldest rock inBritain

13 NovemberMulti-celledanimals

15 NovemberAnimals withshells

13–27 December Dinosaurs

31 December Ice age started 8pm Christ born 13.8 seconds before midnight

JANUARY FEBRUARY MARCH APRIL MAY JUNE JULY AUGUST SEPTEMBER

OCTOBER

NOVEMBER

DECEMBER4600 2500 570

EonPhanerozoic

ProterozoicArchaean

Cen

ozo

ic

Meso

zoic

Palaeozo

ic

Precam

brian

Era

Cen

ozo

ic

Meso

zoic

Palaeozo

ic

Precam

brian

Period

Qu

aternary

Tertiary

Cretaceo

us

Jurassic

Carboniferous

Devo

nian

Silurian

Ord

ovician

Cam

brian

Permian

Triassic

Millio

n years ago

265

140

195

230

280

345

395

445

510

570

4600

Periods in boldtype, epochs innorm

al type

Eras

Age ofbase inm

illionsof years

Countryw

here definedD

erivation ofnam

e

➤

➤➤➤➤➤➤

➤

Archaean Proterozoic Phanerozoic

FFiigguurree 11

33..

Th

e stratigra

ph

ic colu

mn

. At th

e top, key even

ts in E

arth

histo

ry are co

mpressed

into

on

e year to

illustra

te the im

men

sity of th

egeo

logica

l timesca

le. After G

rayso

n (1

99

3).

Table 1.O

rigin o

f the n

ames o

f the tim

e perio

ds in

the stratigrap

hic co

lum

n fo

r the

past 570 m

illion

years.

Cen

ozo

ic Q

uaternary(recen

t life)H

olo

cene

0.01En

gland

Ho

los: w

ho

leP

leistocen

e1.6

Englan

dP

leiston

: mo

stTertiaryP

liocen

e5.3

Englan

dP

leios: m

ore

Mio

cene

23En

gland

Meio

n: less

Oligo

cene

36.5G

erman

yO

ligos: few

Eocen

e53

Englan

dEo

s: daw

nPalaeo

cene

65G

erman

yPalaeo

s: old

Meso

zoic

Cretaceous140Fran

ceC

reta: chalk

(mid

dle life)

Jurassic195

Switzerlan

d

Jura M

ou

ntain

sTriassic

230G

erman

yT

hree-fo

ld d

ivision

recognised in G

ermany

Up

per

Permian

280R

ussia

Th

e tow

n o

f Perm

Palaeozo

icin

Ru

ssia(an

cient life)

Carboniferous345

Englan

dC

arbo

n: co

alD

evonian395

Englan

dD

evon

Low

er Silurian

445W

alesSilu

res: Celts o

f the

Palaeozo

icW

elsh B

ord

ers(an

cient life)

Ordovician

510W

alesO

rdo

vices: Celts o

f N

orth

Wales

Cambrian

570W

alesC

ambria: Latin for W

ales

Th

e stratigra

ph

ic colu

mn

is the a

rray o

f geolo

gical tim

e un

its tha

t results fro

m sta

ckin

gth

em vertica

lly, with

the o

ldest a

t the b

ase, overla

in b

y successively yo

un

ger un

its. In th

e1

83

0s, Sir C

ha

rles Lyell recogn

ised th

at in

the C

enozo

ic (som

etimes sp

elt Ca

inozo

ic) Era

modern

sp

ecies a

ppea

r a

s fo

ssils, beco

min

g pro

gressively m

ore

abu

nda

nt

in yo

un

gersed

imen

ts. For exa

mple, 3

% o

f Eocen

e species a

re alive to

day, a

nd a

s ma

ny a

s 30

–50

% o

fP

liocen

e species exist to

day. Lyell ch

ose to

use G

reek p

refixes to su

bdivid

e the E

ra a

ccord

ing

to th

is observa

tion

. After W

ilson

(19

94

).

19

Fossils

Palaeontology is thestudy of fossils. Fossilsare the remains or

‘traces’ of plants or animalswhich have been buried bynatural processes and thenpermanently preserved.These include skeletalmaterials (e.g. bones andshells), tracks, trails andborings made by livingorganisms, as well as theirexcrement. They alsoinclude the impressions(moulds or casts) oforganisms on rock surfaces,and even actual biologicalmaterial. For fossilisation tooccur, the death of a plant oranimal must normally befollowed by its rapid burial,otherwise the remains willbe physically broken up ordestroyed by scavengers orby chemical and biologicaldecay.

Once the organic trace hasbeen buried it may bepreserved as unaltered material, such asoriginal skeletal material, mammoths frozen inpermafrost or insects in amber. Alternatively itmay be petrified. In this case, minerals haveeither replaced the previous cells or tissue, orfilled in pores in the original material.Sometimes the sediment around a fossil maysurvive but the fossil itself is dissolved away,leaving a mould which may later becomeinfilled with another mineral. This creates acast of the original fossil.

Fossils are named in the same way as livingplants and animals, and are important as ameans of determining the relative ages ofrocks. They can be used to reconstruct adetailed history of life on Earth and explain therate and pattern of evolution and the nature ofancient environments and ecosystems. Theimportance of fossils is illustrated in thediagram.

The photograph shows a fossil ammonite, Asteroceras obtusum, fromCharmouth, Dorset. Although superficially like a snail shell, it is actuallythe remains of a cephalopod. Modern relatives include the squid, octopusand Nautilus. Because of the relative abundance of ammonite fossils, andthe relatively rapid evolution of different species, they provide useful‘markers’ for comparing ages of rocks at different places. Photo: K. N. Page.

Some geological patterns

Even a fairly superficial examination of thegeological map of Britain shown in Figure 11reveals some significant patterns in the

distribution of ages and types of rock that offer cluesabout the geological history of the area. South-eastof a line between the mouths of the Rivers Tees andExe there are broad bands of Permian, Triassic,Jurassic, Cretaceous and Tertiary rocks. This patternis relatively simple compared with that displayed byolder rocks to the north-west. The Permian–Tertiaryrocks reflect the simple geological structureunderlying this area. For example, north of London,the rock layers are inclined gently (by a matter of afew degrees) to the east and south-east, and so areyounger in these directions. London is situated inthe centre of a ‘basin’ in which rocks of Tertiary ageare preserved. This is because a broad fold, termeda syncline exists here. To the south of the LondonBasin another fold occurs, bending the strataupwards into an arch, or anticline, so that olderstrata are exposed in the Weald (Figure 14). TheNorth and South Downs are the topographicexpression of the Wealden Anticline, produced


FFiigguurree 1155.. The areas of higher ground in Britain.Nearly all of these are coincident with the relics of pastmountain chains (compare with Figure 16). AfterWilson (1994).

FFiigguurree 1144.. The geological structure of south-east England, showing major topographic features associated withthe Wealden Anticline, and the London Basin (syncline). Note that the Hastings Beds, Weald Clay, LowerGreensand, Gault Clay and Chalk comprise the Cretaceous shown on Figure 13. After Edmunds (1983).

20

Some geological patterns

21

FFiigguurree 1166.. British mountain belts. ((aa)) Map showing the distribution of the major ancient mountain belts ofBritain. Faults are major planar structures across which rocks have been displaced vertically or laterally. Forexample, the area in Scotland between the Highland Boundary Fault and the Southern Uplands Faults has beendisplaced downwards between the two faults, whereas lateral displacement occurred along the Great Glen Fault.((bb)) Chart summarising the ages of mountain building events and igneous activity. After Dunning et al. (1978).

respectively by northward and southwardinclinations of the Chalk. The Chalk extendsbeneath the London Basin, reappearing to thenorth-west, where it forms the Chiltern Hills (here,it is inclined to the south-east).

The regions exhibiting more complex patternsvisible in the western and northern areas of Figure11 are generally highland areas (Figure 15). Theseare formed of Palaeozoic or older rocks, fromsedimentary, igneous and metamorphic origins.These harder rocks are more resistant to erosionthan the Mesozoic and Tertiary sedimentary rocksto the east and south-east. In fact, these areas arerelics of former mountainous areas comparable ingrandeur with the Alps or Himalayas of today.

Mountain building episodes

Figure 16 shows the distribution of rocks inBritain associated with mountain buildingepisodes. The Caledonian mountain belt

resulted from the closure of a proto-Atlantic oceanbetween ‘North America’ and ‘Greenland’ and‘Europe’. The Variscan mountain belt was formedby closure of a former ocean which separatedsouthern ‘Britain’ and most of ‘Belgium’ from therest of ‘Europe’. By closing the present-dayAtlantic Ocean (Figure 17), the distribution ofrocks caught up in these two mountain buildingepisodes shows that they were once relatively longbut narrow regions. The global pattern of crustalmovements that causes mountain building (oftenreferred to as ‘orogenesis’) is explained on thefollowing pages.

Mountain building results in the deformation ofpreviously deposited sediments and volcanic rocksto produce complex fold structures. Thisdeformation also results in the thickening of theEarth’s crust, so that some rocks are buried deepbeneath the Earth’s surface, where extremely hightemperatures and pressures produce metamorphicrocks. The thickening of the crust results in uplift,as the rocks that comprise mountain belts are lessdense than those beneath, and so they ‘float’ ondeeper layers, much like an iceberg floats in water.As with icebergs, the deeper the submerged part,the higher the relief at the surface.

MOUNTAIN BUILDING AND PLATETECTONICS

As already stated, mountain building is linkedto the closing of former oceans. Today (andin the geological past) oceans are floored by

crustal material that has a greater density thancontinental crust. As shown in Figure 18, the crustforms the thin outer skin of the Earth. Beneath it,in a concentrically layered structure, is the mantleand the core. So the Earth is rather like a sphericalavocado pear. The thin green skin represents thecrust, the yellow flesh the mantle, and the stone atthe centre the core.

It is known from a variety of lines of evidence(including direct measurement from satellites) thathorizontal movements occur in the Earth’s crust.In fact, different parts of the crust move indifferent directions. The crust consists of a seriesof slabs or tectonic plates: where they collide ormove apart, there are zones of earthquakes andvolcanic activity, but there is little activity away


22

FFiigguurree 1177.. The distribution of the Caledonian andVariscan mountain belts on a map of the continentsreassembled to the positions they occupied before theopening of the present-day Atlantic Ocean. Earlyprotagonists of continental drift used reconstructionssuch as these as evidence in favour of the former unityof now widely separated continents. After Wilson(1994).

Mountain building and plate tectonics

from the boundaries between the plates.Figure 19 shows the plate boundaries

associated with South America and Africa, twocontinents that are moving slowly apart at aboutfour centimetres per year — twice the rate atwhich human fingernails grow. This means thatthe South Atlantic is getting wider. In fact, newoceanic crust is being formed along the Mid-Atlantic Ridge as basaltic magma wells up from themantle to form both intrusive and extrusiveigneous rocks. The ridge is associated with anarrow zone of shallow earthquakes.

To the west of South America, the Pacificoceanic crust is moving eastwards, plungingbeneath the continental crust, where it enters ahotter region and begins to melt. The resultantmagma rises upwards, melting some of thecontinental crust on its way to produce granites.Some of the magmas, which are very viscous, doreach the surface and cause explosive volcanicactivity. This plate collision zone is also

characterised by a zone of earthquakes beneathSouth America, as well as an ocean trench and theAndean mountain belt.

Figure 20 shows the distribution of the crustalplates around the world. Most of the plateboundaries shown on this map fall into threecategories — constructive, destructive andconservative — and can be described as follows:

FFiigguurree 1199.. The relation-ships of three crustalplates in the Earth’ssouthern hemisphere.The thickness of thecrustal layers is not toscale. New oceanic crustis constantly formingalong the Mid-AtlanticRidge. After Wyllie(1976).

FFiigguurree 1188.. The structure of the Earth. ((aa)) Diagrammaticsection through the Earth showing the core, mantle andcrust. The crust is too thin to show to scale on thisdiagram: variations in its thickness are depicted in ((bb)),a generalised section through the Earth’s crust showingvariations in the thickness of continental and oceaniccrust. Oceanic crust is between 2.8 and 2.9 times denserthan water, and is similar in composition to rocks suchas basalt and gabbro; continental crust is less dense (2.6to 2.8 times as dense as water), with a compositionsimilar to granite. Continental crust is less dense andmuch thicker than oceanic crust, so it floats higher onthe mantle. After Wilson (1994).

23

❏ Constructive plate boundaries: where basalticmagma rises from the mantle to form ocean ridgessuch as that running down the middle of theAtlantic. They are also characterised by shallowearthquakes (down to 5 km depth).❏ Destructive plate boundaries: where oceaniccrust plunges beneath continental crust. This processis called subduction: it is associated with deep oceantrenches and an inclined zone of earthquakes downto depths of several hundred kilometres. Subductionresults in the melting of crustal material which risesto form plutons (see Figure 12) within the overlyingcontinental crust, and if they reach the surface theycause explosive volcanic activity. Destructive plateboundaries also occur where two slabs of continentalcrust collide (such as in the Himalayan region today).Most of the Pacific Ocean is ringed by destructiveplate margins; on its western side many such marginsare marked by ocean trenches and associatedvolcanic islands arranged in an arc-like pattern, suchas the Japanese islands.

❏ Conservative plate boundaries: where platesslide past each other, causing shallow earthquakes(the best known example is the San Andreas Fault inCalifornia).

What causes the movement of crustal plates?Basically, plate movement is the mechanism bywhich the Earth loses its internal heat generated bythe breakdown of radioactive elements present inthe crust and mantle. The internal heat drives aseries of convection currents in the mantle whichin turn drive plate movement (Figure 19),although the exact linkage between thecurrents and the plates is not clear. Are theypushed apart along constructive boundaries,or pulled down along destructive boundaries?As yet there is no consensus among Earthscientists.

Figure 21 shows, in cross-section, an idealisedsequence of events in a cycle of ocean opening and‘closing’, culminating in mountain building. As the


FFiigguurree 2200.. The present distribution of crustal plates and the earthquake activity at their boundaries. All theconstructive plate boundaries are regions of shallow earthquakes, whereas deeper-focus earthquake zones markthe location of destructive plate boundaries. The rates at which ocean crust is forming at constructive plateboundaries are shown schematically by the width between the parallel lines used to depict them. The directionsof plate movement are shown by arrows, the lengths of which are proportional to the rate of movement: theshorter the arrow, the slower the plate is moving. After Gass et al. (1972).

24

The Precambrian rocks of Britain

25

FFiigguurree 2211.. Sequence ofevents in a cycle of oceanopening and closing,culminating incontinental collision. It ispossible for both platemargins to be subjected tosubduction (as happenedduring the Caledonianmountain building inBritain), although this isnot shown here.

mountain belt is uplifted it iseroded, and sediments derivedfrom it are deposited inneighbouring lowland areas, orin new oceans formed nearby ifthe continental crust splits uponce more. As the mountains areeroded, they become partlycovered by sedimentary rockswhich overlie the older deformedrocks with an angulardiscordance, producing a majorunconformity (see Figures 29 and37).

Thus plate tectonics is thedriving force behind mountainbuilding. The formation of newoceans and their subsequent‘closure’ produce a variety ofrock types and structures thatenable past plate tectonicprocesses to be interpreted fromthe rock record. At destructive plate margins,sedimentary rocks are folded, faulted and deeplyburied, leading to metamorphism. Igneousprocesses along such margins result in the formationof huge masses of intrusive igneous rocks abovewhich explosive volcanoes occur. Most of thegranite shown on the geological map in Figure 11was produced at destructive plate margins. All theseprocesses result in thickening of the crust, whichthen rides higher on the underlying mantle toproduce mountain belts. Such uplifted areas areaffected by increased rates of erosion, and sedimentsaccumulate on the margins of the newly deformedcontinental crust. The Devonian and Triassicsediments shown in Figure 11 were respectivelyderived largely from the uplifted Caledonian andVariscan mountains.

A GEOLOGICAL HISTORY OF BRITAIN

The Precambrian rocks of Britain

Over 85% of Earth history is represented bythe Precambrian Era, the time betweenconsolidation of the Earth’s crust and the

beginning of the Cambrian Period, about 570million years ago. Less is known about these rocksthan those formed during the last 570 million yearsof the geological history of Britain, because most ofthe early rocks have been eroded, deformed,metamorphosed or buried beneath younger rocks.

No trace has yet been found anywhere on Earthof rocks which date from the first 600 million yearsof the Earth’s history, but rocks and minerals

approximately 4000 million years old have now beenfound in most of the major continents. These rocksprovide evidence of the nature of the early Earth.

During the Precambrian there was more rapidmovement of the plates of the crust because ofhigher levels of heat production (caused byradioactive decay) and because the crust was stillforming and was thinner. Consequently, manyPrecambrian rocks have undergone at least oneepisode of mountain building (orogeny), and somemay have undergone several.

The oldest Precambrian rocks to be found inBritain are the Lewisian gneisses (Figure 22a,coloured pink in Figure 11), in the north-westHighlands and the Western Isles. They wereformed over a period of 2,000 million years and theoldest were formed some 3,300 million years ago.These gneisses show evidence of several episodesof deformation and the intrusion of igneous rock,both associated with mountain building. Theseearly crustal rocks were later overlain byTorridonian sediments, and the Moine and theDalradian metamorphic rocks that show evidenceof a long and complex geological history. Theseunderlie large parts of northern Scotland (grey-green in Figure 11). Sedimentary and volcanicrocks of Precambrian age are also found in Anglesey(Figure 22b), the Welsh Borders, the Malverns andthe Midlands.

Rocks which formed at the end of thePrecambrian show evidence of animal life, andjellyfish-like fossils can be found in the Precambrianrocks of central England (see Figure 3) and parts ofWales.

Since the Precambrian, continuing majorcontinental movements first created and thendispersed a single giant supercontinent, known asPangaea (Figure 23). This single continent formeda vast landmass, the assembly and dispersal ofwhich has left a marked imprint upon Britain’sgeological record. During this time, the crust onwhich ‘Britain’ was situated drifted northwards as aresult of plate movements (Figure 24).

The Cambrian, Ordovician andSilurian rocks of Britain

Rocks of the Cambrian Period, found inScotland, originally formed part of a NorthAmerican continent, and were separated from

the Cambrian rocks of England and Wales by a wideocean, the Iapetus (see Figure 23a). The fossil recordof these rocks includes trilobites, a now extinct groupof arthropods, graptolites (see Figure 39) squid-like

nautiloids and other types of mollusc, demonstratingthat there was a wide range of animal life in thisocean. The Iapetus Ocean reached its greatest widthearly in the Ordovician Period and later began tonarrow. Enormous thicknesses of muddy sandstoneswere deposited on the margins of the ocean. As the


26

FFiigguurree 2222.. Precambrian rocks. ((aa)) The oldest-knownrocks in Britain: the Lewisian Gneiss, in the north-westHighlands of Scotland. Some of these rocks wereformed about 3,300 million years ago, in thePrecambrian Era. Photo: R. Threadgould. ((bb)) ThePrecambrian-age rocks at South Stack, Angelsey weredeformed more than once. Photo: S. Campbell.

b

a

The Cambrian, Ordovician and Silurian rocks of Britain

FFiigguurree 2233.. Continental drift. Simplified maps illustrating how the continents were distributed during Earthhistory, indicating the locations of the different parts (dark shading) which have come together to form present-day Britain. After Wyllie (1976).

27

ocean narrowed, arcs of volcanic islands developedin the ‘Lake District’ (Figure 25) and ‘North Wales’.Mountain building began in Scotland at this time.

Later, in the Silurian Period, the development ofcoral reefs indicates a shallowing of the ocean. TheSilurian fossils show none of the geographicdifferences characteristic of the Cambrian andOrdovician periods, because by this time speciescould move freely between either side of theshrinking Iapetus Ocean. At the end of the Silurian,the climax of the Caledonian period of mountainbuilding occurred as ‘Scotland’ and ‘England’ finallycollided.

The Devonian and Carboniferous rocks ofBritain

The Caledonian mountains were rapidly erodedand great thicknesses of sediment, nowknown as the Old Red Sandstone,

accumulated over much of northern ‘Britain’ andsouth ‘Wales’ during the Devonian Period. In‘Devon’ and ‘Cornwall’ the land was bordered bytropical seas which persisted through the Devonianand Carboniferous periods (see Figure 23).

The Devonian continent supported freshwaterlakes with many fish species. Sediments whichformed near hot mineral-rich springs at lake edges,

about 370 million years ago, have been found atRhynie in Scotland (see Figure 46). These containthe remains of the oldest-known higher plants in theworld. Insect and arachnid fossils are also foundhere, demonstrating that the land was beingcolonised rapidly at that time.

During the early part of the Carboniferous Periodthe remnants of the Caledonian mountains wereflooded by a warm tropical sea in which thick layersof limestone were deposited. In the lateCarboniferous huge deltas invaded this sea. On thesurface of the deltas dense forests of giant horsetails,tree-ferns, giant clubmosses flourished. Theremains of these trees were sometimes buried, to betransformed later into coal (Figure 26). Dragonflies,with a wing span of up to 60 centimetres, and otherinsects and arthropods were common in theseforests, and the first amphibian-like reptile fossils,which are about 340 million years old (Figure 27),have been found in Carboniferous rocks in Scotland.

Towards the end of the Carboniferous Period, anorthward-moving plate collided with the southernmargin of the Old Red Sandstone Continent in south-west ‘England’. This was the final event in theconstruction of the supercontinent Pangaea (seeFigure 23c) some 300 million years ago, and causedthe Variscan Orogeny (Figure 28). The granites ofsouth-west England were intruded at this time.


28

FFiigguurree 2244.. The changing latitude of Britain through geological time. After Lovell (1977).

The Devonian and Carboniferous rocks of Britain

FFiigguurree 2255.. Typical Lake District scenery in the Borrowdale Volcanic Group. The succession of rocks between theLangdale Pikes and Silver Howe represent a six kilometre thickness of volcanic lava and ash, erupted over aperiod of ten million years during the Ordovician Period. Photo: F. W. Dunning.

FFiigguurree 2266.. Carboniferous environments. ((aa)) A coal-bearing sequence exposed in Duckmanton RailwayCutting, Derbyshire; the dark band is a coal seam.Photo: English Nature. ((bb)) Reconstruction of the tropicalforest of northern England during the CarboniferousPeriod. During this time, much of ‘Britain’ was coveredby such forests and swamps. It is from the remnants ofthese forests that much of Britain’s coal reserves arederived. A: a lycopod; B: a cycad; C: the horsetailCalamites; D: Boltonites. Reproduced from Duff et al. (1985).

29

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30


31

The Permian and Triassic rocks ofBritain

Desert conditions prevailed over much ofPangaea during these periods. Vast areas ofsand dunes were preserved as the ‘New Red

Sandstone’ (Figure 29). During the Permian Period aninland sea occupied much of the area of what is nowthe North Sea, and when it began to dry up, evaporitedeposits were precipitated (see Figure 48).

The drier conditions led to evolutionary changes

in the animals and plants. Forests of conifers andcycads (the sago palm is a modern cycad) began toreplace the earlier plant-forms, and about 300 millionyears ago the reptiles became more prolific.

The Jurassic and Cretaceous rocks ofBritain

At the beginning of the Jurassic Period much of‘Britain’ was flooded by a warm sea teemingwith life. In Britain, shallow- marine Jurassic

FFiigguurree 2288.. Hartland Point, Devon. TheseUpper Carboniferous-age rocks werecontorted into tight folds, by the VariscanOrogeny. Photo: A. R. Bennett.

FFiigguurree 2299.. Sully Island, South Wales. Triassic rocks (230 –195 million years old) were formed when ‘Britain’ laywithin the arid belt north of the equator. They lie horizontally on the dipping Carboniferous Limestone. This angulardiscordance is known as an unconformity, and represents a period of several million years when there was nosediment accumulation. The rocks above the unconformity comprise sands and breccias which are interpreted aslake shore deposits. This site is one of the few places in the world where the margin of a former Triassic lake can bestudied. Diagram after Wilson (1994). Photo: C. D. Prosser.

The Jurassic and Cretaceous rocks of Britain


32

FFiigguurree 3300.. Jurassic environments. ((aa)) Plesiosaursfrom the early Jurassic based on specimens collectedin Gloucestershire which are now housed inGloucester City Museum. ((bb)) Scene from mid-Jurassictimes, showing a small lake surrounded by seed fernsand conifers based on the fossils from HornsleasowQuarry, Gloucestershire. Fish (Lepidotus) live in thewater, and frogs are present at the lake sides.Dinosaurs include some of the earliest stegosaurs andmaniraptorans, plated and small carnivorousdinosaurs respectively. A carcass of a large sauropoddinosaur, Cetiosaurus, is rotting in the water, andMegalosaurus scavenges. Lizard-like animals,crocodiles, pterosaurs, mammals and mammal-likereptiles complete the scene. Paintings by PamBaldaro. Reproduced by permission of the Universityof Bristol.

a

b

FFiigguurree 3311.. The Seven Sisters chalk cliffs in East Sussex. The geomorphology of the cliffs is the result of marineerosion into a series of valleys and intervening ridges. Photo: N. F. Glasser.

The Jurassic and Cretaceous rocks of Britain

33

FFiigguurree 3322.. The Storr, Skye. The photograph shows the landslipped masses of basalt of the Skye Main Lava Serieswhich occupy the foreground. Beyond the Old Man of Storr pinnacle, further lava flows of the Series form left-to-right-dipping scarps. Photo: David Noton Photography.

rocks occur in a belt from Dorset to Yorkshire, inSouth Wales and in scattered patches in the islandsof north-west Scotland and in northern Scotland(olive-green in Figure 11). The fossil record of theserocks demonstrates that cephalopods wereparticularly abundant, especially ammonites andbullet-shaped belemnites. Bivalve and gastropodmolluscs, sea urchins and fish were also plentiful.Large marine reptiles such as ichthyosaurs andplesiosaurs were numerous (Figure 30a). Thereptiles also flourished on the land and evolved intomany forms, including the dinosaurs (Figure 30b).By about 210 million years ago, the first mammalshad evolved, and 150 million years ago the first truebirds appeared, although they were a relativelyinsignificant part of the fauna at the time.

Thick deposits of calcareous ooze, formed fromthe remains of plankton, accumulated in the lateCretaceous seas over much of ‘Britain’. These becamethe Chalk which is now only found in eastern andsouthern Britain (Figure 31) and Northern Ireland.Towards the end of the Cretaceous Period, sea levelsreached an all-time high and most of ‘Britain’ wassubmerged beneath the sea.

During the Triassic and Jurassic periods, thesupercontinent of Pangaea began to be slowlypulled apart (see Figure 23), a process whichaccelerated in Cretaceous and Tertiary times.

The Tertiary rocks of Britain

The fossil record indicates that many plants andanimals became extinct at the Cretaceous–Tertiaryboundary about 65 million years ago. This massextinction was perhaps the result of a globalcatastrophic event, such as a meteorite impact ormajor volcanic eruption. On land the dinosaurs andpterosaurs became extinct, but in the Tertiary Periodthe mammals diversified and flowering plants beganto predominate at the expense of the earlier planttypes. In the sea, gastropods and bivalve molluscsproliferated, but the ammonites, belemnites andmany types of marine reptile became extinct.

As the Atlantic Ocean opened between‘Greenland’ and ‘Scotland’, a chain of volcanoeserupted, flooding the landscape with extensive lavaflows. Their eroded remnants can now berecognised on Skye (Figure 32), Rum, Mull, theArdnamurchan Peninsula, Arran and in Antrim. Later,‘Africa’ collided with ‘Europe’ to form the Alps. Theeffects of this mountain building episode can be seenin the fold structures of southern Britain (see Figure14).

‘Britain’ continued to move northwards from thetropics into the cooler mid-latitudes (see Figure 24).

Quaternary sediments and landforms ofBritain

The long geological history of Britain hasinfluenced its landscape, but much of itspresent shape was fashioned during the

Quaternary Period (‘Great Ice Age’), during the lasttwo million years or so. The Quaternary consisted ofseveral ice ages separated by temperate interglacialclimates. During the ice ages, glaciers grew in themountains and occasionally large ice sheetsadvanced into lowland ‘Britain’. On one occasion,ice extended as far south as ‘London’ (Figure 33).

Early in the Quaternary Period, these ice agesoccurred about every 41,000 years, when theuplands of England, Scotland and Wales wereprobably entirely ice-capped on each occasion,although the evidence has been destroyed by laterglaciations. Over the last 900,000 years, however,the rhythm of the major ice ages changed and theyhave occurred about every 100,000 years. It wasduring this time that major glaciations greatlymodified the landscapes of Britain (Figure 34). Aswell as eroding deep valleys, the ice sheets depositedclays, sands and gravels, producing landforms suchas eskers and drumlins, as well as a widespreadmantle of boulder clay (‘till’) across parts of thecountry (Figure 35).

Areas beyond the ice-sheet margins wereaffected by frost, ice and wind, in a cold and dryclimate, like the Arctic of today. Such conditionsare called ‘periglacial’. Slopes were attacked byfreezing and thawing processes to create rockdebris and produce a widespread layer ofperiglacial deposits. Rivers were unable totransport all of this material, so depositionoccurred on wide floodplains with braidedchannels. Extensive periglacial gravel deposits arewidespread in southern England.

During the ice ages, global sea levels wererelatively low because ocean water was locked upin the ice sheets. For example, at the peak of thelast ice age, some 22,000 years ago, the sea levelwas approximately 120 metres below that of today.Thus, ‘England’ was joined to ‘Europe’ at that time.

In the glaciated areas of Britain, the weight ofthe ice depressed the Earth’s crust. When the iceretreated, and before the crust ‘rebounded’ to itsformer position, the sea fashioned shorelines at


34

levels relatively lower than at the present. When thecrust finally returned to its pre-glacial level, suchshorelines were uplifted above present-day sea levelto form ‘rebound’ raised beaches. There are manysuch beaches in Scotland (see Figure 10).

Ice-age conditions were separated by periods oftemperate interglacial climate, when Britain wassometimes at least as warm as today, and mixedoak temperate forests became established. Duringthe interglacials there was less ice on the Earth’ssurface and beaches formed at times of relativelyhigh sea level. These are now found in southernBritain. Many have been raised by gradual long-term uplift.

The flora and fauna of Britain responded to theclimatic changes during the Quaternary Period.Variations in the type and distribution of plants and

animals have been reconstructed from fossilremains, including pollen grains and fossil bonespreserved in peat bogs, as well as lake and cavesediments. This is evident at sites such as WestRunton, Norfolk, for example (Figure 36).

Fossils of mammals such as hippopotamus,rhinoceros, elephant, cave hyena, woolly mammothand early humans have been found in Britain. In theraised beach deposits at Boxgrove, West Sussex,hominid remains (a tibia bone and a tooth) andstone tools have been estimated at between 400,000and half a million years old. At Swanscombe, inKent, a skull intermediate in form between Homoerectus and Neanderthal Man has been found insediments about 400,000 years old. Stone tools ofan even older age have also been found at HighLodge, Suffolk, and Torquay, Devon.

FFiigguurree 3344.. Upland glaciation, Snowdonia, Wales. Thephotograph shows a series of cirques. A cirque is anarmchair-shaped hollow, with a steep rock wall at therear, and a lip or threshold at the front. The rock headwall is fashioned first by weathering and rockfallprocesses, whereas the floor of the basin is eroded andmoulded by glaciers which occupied the hollow.Where two cirques meet, a precipitous divide called anarête develops (to the right in the photograph). Photo:S. Campbell.

FFiigguurree 3333.. Ice margins of British glaciations. The agesof these ice advances are:❏ Loch Lomond Advance, 11,600 to 12,800 years ago❏ Late Devensian glaciations (‘the last glaciation’),

23,000 years ago❏ Early Devensian Glaciation, about 60,000 years ago❏ Ridgacre Glaciation (West Midlands), 160,000

years ago❏ Anglian Glaciation, 450,000 years ago❏ Bristol-Scilly Islands Glaciation, about 640,000 years

ago.

Quaternary sediments and landforms of Britain

35


FFiigguurree 3355.. Schematic diagrams showing the formation of glacial depositional landforms and deposits. ((aa)) Flowtills form on the surface of the retreating glacier from thick sequences of englacial debris. ((bb)) Till cover inhibitsmelting of underlying ice which is left behind during glacier retreat as an ice-cored moraine ridge. Supraglacialflow till is still active. ((cc)) Outwash from the active glacier is forced to flow between ice-cored ridges and tills flowinto the outwash systems. When the outwash dries up, the flow till forms a capping. ((dd)) Dead ice melts, thusreversing the topography and leaving melt-out till in its place. The kame sediments show collapse structures. Suchsequences are extremely common in lowland Britain. ((ee)) and ((ff)) Development of the features of a glaciatedvalley. The principal features are lateral and medial moraines and kame terraces. ((gg)) The formation of thesubglacial/proglacial sediment features. The till surface bears drumlins and on it are superimposed flutedmoraine ridges; push-moraine ridges are associated with readvance of the glacier front, either in winter duringa general retreat phase or in response to longer term cooling; lee-side till forms in a natural cavity where debrisfalls from the ice roof. Relatively rare eskers form in subglacial or englacial stream channels; proglacial outwashcuts through the till; kettle holes form in old outwash where stagnant ice blocks melt-out (the underlyingsediments show collapse structures). A simple stratigraphy of outwash on till is produced by a single glacialepisode of advance and retreat. After Boulton and Paul (1976).

36

Britain after the last ice age

Following the disappearance of the last uplandglaciers from Britain 11,500 years ago, asuccession of vegetation communities

recolonised the land and geomorphologicalprocesses continued to modify the landscape. Onthe coast, erosion and deposition caused byvariations in the relative level of land and sea aswell as the variability of coastal processes, led tochanges in the shape of coastlines. Beaches, dunesystems and shingle structures also developedwhere there was a ready supply of sediment.Inland, slopes left after the ice had melted wereaffected by mass-movement processes, from soil-creep to landslides, while rivers cut channelsthrough the glacial, and other, sediments on valleyfloors.

The water released to the oceans from themelting of ice sheets in Eurasia and North Americaflooded any connection between Ireland andBritain. Britain also became separated fromcontinental Europe. At that point, further naturalcolonisation of plants and animals from thecontinent was inhibited.

Changes in vegetation over the last 11,500 yearsare shown by pollen and other plant remainspreserved in bogs and lake deposits. The sequenceof sediments at such sites can also be used to inferchanging environmental conditions and to providebaseline information against which past andpresent human impacts on the environment maybe assessed.

Present-day Britain

Contemporary geomorphological processescause changes that are, perhaps, not asdramatic as they were during the ice ages.

But coastal and river processes can cause majorchanges over only a few centuries, or evencatastrophically, as in the case of the Exmoorfloods and North Sea storm-surge flooding, both in1953. Other examples of geomorphologicalactivity today include weathering and mass-movement processes.

British landscapes have been further diversifiedby human activity, which has modified slopes andrivers, and provided a cultural overlay of a series oflandscapes altered over many historical periods.Historically, perhaps the greatest changes havebeen those of marsh and heath reclamation,woodland clearance and the development ofagricultural field systems.

THE IMPORTANCE OF BRITAIN INTHE DEVELOPMENT OF GEOLOGY

The record of Earth history has beenassembled by the careful accumulation andconsideration of evidence from the Earth’s

rocks. British natural historians, scientists andscholars played a pioneering role in developing thesciences of geology and geomorphology. Thewealth of evidence in Britain’s landscape enabledthem to develop their ideas and theories. A briefaccount of the early development of geologicalscience is given here to show how importantBritain’s Earth heritage was in developing theprinciples of geology.

During the latter part of the eighteenth and theearly part of the nineteenth centuries, majoradvances in geology occurred. In 1795, JamesHutton published Theory of the Earth, which is

FFiigguurree 3366.. West Runton, Norfolk. Sediments exposed inthe cliff and on the foreshore accumulated during twointerglacials and three ice ages. Fossil pollenindicating the presence of temperate forests has beenobtained from the interglacial deposits, while the ice-age deposits show permafrost structures and subarcticherb floras. The dark band at the bottom of the cliff isthe ‘Freshwater Bed’, deposited by a river. Photo: N.F.Glasser.

Britain in the development of geology

37

regarded as the first concerted attempt to explaingeological phenomena in scientific rather thanbiblical terms. Hutton defined the principle ofuniformitarianism, which is the proposal thatprocesses observed today can be used to interpretthe past. He recognised the operation of processesover long periods of geological time and cycles inEarth history (Figure 37). Some of his ideas weredeveloped by John Playfair in his Illustrations ofthe Huttonian Theory of the Earth (1802).Playfair used British examples, particularly relatingto the gradual, fluvial origins of valleys, a novelconcept at a time when catastrophic theory (basedon the biblical flood in Genesis) dominated.Hutton’s work was later developed by CharlesLyell, an immensely influential figure. In ThePrinciples of Geology (1830), he provided a

theoretical basis for geology by applying theprinciples of uniformitarianism.

In 1807 the Geological Society of London wasfounded, the first geological society in the world.It became a centre for geologists to meet todiscuss new discoveries and theories. Not longafterwards, in 1815, William Smith, a landsurveyor and civil engineer, published a geologicalmap of England and Wales, based on principlesdeveloped from his early observations aroundBath, including canal excavations. There heestablished a system of correlating rock strata bycomparing their fossil contents. This became thebasis of modern stratigraphy. He was described bythe President of the Geological Society, at anaward ceremony in 1831, as ‘the father of Englishgeology’.

FFiigguurree 3377.. Hutton’s Unconformity at Siccar Point,Berwickshire, is one of the most famous and importantgeological localities in the world. The section at SiccarPoint shows upturned Silurian sediments overlain bysediments from the Old Red Sandstone. Theunconformity surface which separates these two sets ofrocks represents a significant break in the continuity ofthe geological record. The portrait of James Hutton by SirHenry Raeburn (detail) is reproduced by permission ofthe Scottish National Portrait Gallery. Photographreproduced by permission of the Director, BritishGeological Survey. NERC copyright reserved.


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In 1835 the Geological Survey of Great Britainwas established, the first in the world, to carry outdetailed geological mapping of the whole country.Its first Director, Sir Henry de la Beche, producedthe first survey memoir, describing themetalliferous ore fields of south-west England. In1837 the Survey was given accommodation inLondon, which included a Museum of PracticalGeology. In 1934 the museum relocated to SouthKensington, where it now forms the EarthGalleries of the Natural History Museum.

In the 1830s, Sir Roderick Impey Murchisonbegan a study of the rocks of south and centralWales. He compared rocks at different localities bymeans of the fossils they contained, includingdifferent species of trilobite. In 1858 he publishedSiluria, naming this sequence of rocks after anancient Celtic tribe, the Silures. Meanwhile, AdamSedgwick was investigating the rocks of the LakeDistrict and North Wales. These are older than therocks that were studied by Murchison and contain

some of the oldest fossils in Britain. He namedthese rocks the ‘Cambrian’, based on the LatinisedWelsh name for Wales Cymru. As a consequenceof their further studies in south-west Englandtogether they named the Devonian System (Figure38). Murchison and Sedgwick also discoveredfossil fish in the Devonian Old Red Sandstone ofScotland. These finds were added to by HughMiller and Louis Agassiz, who were able to portraythe nature of the freshwater fish of the Old RedSandstone.

Although some Cambrian and Silurian rocks asoriginally defined by Murchison and Sedgwickwere quite distinct, others contained similarassemblages of fossils. A controversy eruptedbetween them which was not resolved until aftertheir deaths. Subsequently, Charles Lapworth, aclergyman, spent his spare time studying the rocksaround Galashiels in southern Scotland. He lookedparticularly at graptolite fossils (Figure 39). Incomparing his findings with those of Murchison and

The importance of Britain in the development of geology

39

▲ Sir RoderickImpey Murchison

Adam Sedgwick

FFiigguurree 3388.. Lummaton Hill Quarry Site of Special Scientific Interest, Torquay, Devon. The rocks exposed in thequarry are massive limestones which were deposited in the later part of the Middle Devonian Period (theGivetian Stage). The limestone contains shell-rich pockets seen here in the upper part of the face. This locality isof great historical importance because the rich faunas it has yielded were used, in part, to characterise theoriginal Devonian System of the pioneering geologists Sedgwick and Murchison. Portraits reproduced withpermission of the Director, British Geological Survey. NERC copyright reserved. Photo: K. N. Page.

▲

Sedgwick, he concluded that the overlappingstrata were sufficiently distinct to represent aseparate period, thereby resolving the earliercontroversy. He named this the Ordovician, afterthe Ordovices, another Celtic tribe whichinhabited part of Wales. Thus the Cambrian,Ordovician, Silurian and Devonian Periods were allnamed in Britain.

In the 1820s Mary Anning collected and soldJurassic fossils in Lyme Regis, Dorset (Figure 40).She discovered remarkably complete specimens ofthe marine reptile Ichthyosaurus; the first- knownarticulated skeleton was discovered by her whenshe was a girl of eleven. She also found the firstalmost complete Plesiosaurus skeleton in 1823and remains of the flying reptile Dimorphodon in1828. These finds proved to be important for thestudy and interpretation of the evolution ofreptiles.

In 1822, Mary Ann Mantell discovered fossil

teeth in the Cretaceous Wealden rocks whilewalking in Ashdown Forest, Sussex. These werelater identified as those of a large herbivorousreptile, Iguanodon. In 1824, a fossil thigh bonecame into the hands of Professor WilliamBuckland, who named the animal Megalosaurus,later discovered to be a large carnivore. Furtherfinds included fossils of the armouredHylaeosaurus, described by Charles Mantell (MaryAnn’s husband) in 1832, and a large sauropoddinosaur, Cetiosaurus, from the Oxford Clay near

FFiigguurree 3399.. Graptolites first become significant in thegeological record in the early Ordovician Period, andbecame extinct in late Carboniferous/early Permiantimes. They were colonial organisms living near thesea-surface, consisting of one or more branches (stipes).The individuals of the colony lived in cups along thestipe. Their evolutionary development, as seen infossils, led to the definition of the Ordovician Period.The photograph shows the graptolite Didymograptusmurchisoni, from Dyfed, from rocks which are Llanvirnin age (between 455 and 470 million years ago).Photo: G. Larwood. Diagram after Rickards (1993).


40

The importance of Britain in the development of geology

41

Peterborough. In 1841, at a meeting of the BritishAssociation for the Advancement of Science, DrRichard Owen first suggested that Iguanodon,Megalosaurus (see Figure 43) and Hylaeosaurusshould together be called the Dinosauria. Thus itwas the discoveries of British fossil reptiles whichled to the naming of this group.

Significant advances in the understanding of iceages and landscape changes were also made in Britainduring the nineteenth century. In the early 1840s theevidence of glacial landforms in Scotland made asignificant impression on the Swiss geologist LouisAgassiz, a leading figure in advancing ‘the GlacialTheory’. He helped develop thinking on thepossibility of glaciation in areas where there were nomodern glaciers. In 1842 Charles Darwin andWilliam Buckland also confirmed the ideas of Agassizin Wales. Robert Jamieson and Charles Maclarenplayed an important part in the wider disseminationof the ideas Agassiz advocated, together with those ofother early glacialists.

Maclaren is also credited with first recognisingthe sea-level changes associated with glacio-eustasy (changes in global sea level as water, oncelocked up in ice sheets, was released onsubsequent melting). Thomas Jamieson was thefirst to recognise complementary glacio-isostaticchanges in sea level (‘rebound’ of continentalcrust when the weight of ice which depressed it isremoved upon melting of the ice). His conclusionwas based on detailed studies of raised beachdeposits in the Forth Valley.

A r c h i b a l dGeikie, DirectorGeneral of theGeological Survey,Andrew Ramsay andJames Croll identified multiple phases of glaciationin the sedimentary record. Croll also recognisedthat the changes in climate were controlled byvariations in the Earth’s orbit around the Sun andthat ocean currents played a major part in heattransfer from the tropics to higher latitudes.Geikie contributed significantly to theunderstanding and interpretation of the linksbetween geology and geomorphology. Hisyounger brother, James, published The Great IceAge in 1874, a highly influential book with aninternational perspective on the Ice Age.

During the nineteenth and twentieth centuriesthe Geological Society of London, the BritishGeological Survey and the universities, amongstothers, advanced the study of geology andgeomorphology in Great Britain. Knowledge ofthe geological column has been refined byinternational collaboration, which has alsofacilitated the correlation of geological events inBritain with those elsewhere. At the same time,our understanding of the geological andgeomorphological processes which have been atwork throughout the period of geological historycontinues to be deepened, and methods forlocating economic resources below ground alsocontinue to be developed and refined.

FFiigguurree 4400.. The Jurassicrocks of the cliffs nearLyme Regis and portraitof Mary Anning.Portrait reproduced bypermission of TheNatural HistoryMuseum, London.Photo: P. Doyle.

The Geological Conservation Review

Chapter 4

In a country such as Britain, with a relativelysmall land area and a population of over 55million, there are many demands on land that

may conflict with site conservation. There is ademand for hard rock and sand and gravel to meetthe requirements of the construction industry, aswell as clay for bricks, limestone for cement, andlandfill sites for waste disposal. Just as it isimpracticable to conserve every rock exposure, itis essential to conserve those that make a uniquecontribution to Britain’s Earth heritage. Theidentification of those sites that need to beconserved has been the purpose of the GeologicalConservation Review.

From the late 1940s until the late 1970s, theidentification of the most important Earth heritagesites was undertaken by the Nature Conservancy(1949–1973) and then the Nature ConservancyCouncil (1973–1991) on the basis of availableinformation and the advice of Earth scientists.

The launch of the Geological ConservationReview in 1977 marked a more systematicapproach to site selection. The objective of thereview was to identify those sites needed to showall the key scientific elements of the Earth heritageof Britain. Site selection was undertaken between1977 and 1990 by the Nature Conservancy Council.It covered both the geology and geomorphology ofBritain and involved several hundred scientists fromhigher education, government, industry and thevoluntary sector. The sites selected were calledGeological Conservation Review sites and theyform the basis of statutory Earth heritageconservation in Britain. The current responsibilityfor site selection and deselection rests with thestatutory nature conservation agencies: theCountryside Council for Wales, English Nature andScottish Natural Heritage.

The results of the Geological ConservationReview programme are being published in a seriesof 42 volumes, each of which provides a publicrecord of the evaluation of each GeologicalConservation Review site placed in a national and,where appropriate, international context.

PRINCIPLES OF SITE SELECTION

Aims of the Geological ConservationReview

From the outset, the Geological ConservationReview used the highest scientific standardsto identify systematically the key Earth

science sites in Britain. The site series wouldreflect the range and diversity of Great Britain’sEarth heritage, and each site would ultimatelysatisfy the legal requirements for notification as aSite of Special Scientific Interest by reason of its‘geology or physiography’ (‘physiography’ issynonymous with ‘geomorphology’). Thenotification of Sites of Special Scientific Interestunder the National Parks and Access to theCountryside Act 1949 and subsequently under theWildlife and Countryside Act 1981, is the mainmechanism of legal protection in Great Britain (seeinformation box on page 46).

To achieve these aims, criteria and guidelineswere developed. These can be encapsulated inthree distinct, but complementary, components:

1 sites of importance to the internationalcommunity of Earth scientists

2 sites that are scientifically importantbecause they contain exceptional features

3 sites that are nationally important becausethey are representative of an Earth sciencefeature, event or process which isfundamental to Britain’s Earth history.

‘Nationally important’ in the context of GeologicalConservation Review site selection refers toimportance to Great Britain as a whole, and meansthat any site chosen for the GeologicalConservation Review has been assessed, whereverpossible, against comparable features, where theyexist, across the whole of Great Britain.

Each site selected for the GeologicalConservation Review is of at least nationalimportance for Earth heritage conservation, andmany of the sites are of international importance.

THE FIRST COMPONENT —INTERNATIONAL IMPORTANCE

The first component for GeologicalConservation Review site selection ensuresthat geological and geomorphological sites

of international importance are included so thatour international responsibilities are met. Fivemain types of internationally important GeologicalConservation Review site can be recognised:

❏ time interval or boundary stratotypes; forexample, the boundary stratotype at PitchCoppice, Herefordshire (Figure 41; see alsoFigure 2)

The first component — international importance

45


46

Sites of Special Scientific Interest(SSSIs)

Since the establishment of government-based conservation agencies in the late1940s, the identification of a series of

discrete sites for protection has become theprincipal instrument of nature conservation.During the 1980s, attention moved towardsmore holistic and ‘wider countryside’approaches to conservation, and this trendcontinues. Despite this, site-based conservationremains an indispensable means of protectingspecific features of scientific interest. TheBritish SSSI system is a conservation mechanismthat confers legal protection on sites.

An SSSI is the designation by law of an area ofBritain that is, in the opinion of the statutoryagency concerned, of special scientific interestfor its flora, fauna, geological orgeomorphological features. Such areas may belarge or small. The duty to designate an SSSI isvested in the three nature conservationagencies, the Countryside Council for Wales,English Nature and Scottish Natural Heritage.SSSI status provides a mechanism forconsultation about threats or activities that mayendanger the special interest of a site.Designation of a site as an SSSI does not over-

rule existing planning permission.A similar system operates in Northern Ireland,

where designation of a site as an Area of SpecialScientific Interest (under the NatureConservation and Amenity Lands (NorthernIreland) Order 1985, as amended by theNature Conservation and Amenity Lands(Amendment) (Northern Ireland) Order 1989)affords a comparable degree of protection.

The series of 3002 Geological ConservationReview sites is likely to become about 2300 Earthscience SSSIs when the process of notification iscomplete (some SSSIs contain more than oneGeological Conservation Review site within theirboundaries). On average, 400 applications fordevelopment or substantial change are made eachyear across Britain at these sites. Of theseproposals, more than 90 would, if carried out,cause deterioration of the Earth science feature ofinterest at the site, and about 20 would causeserious damage or destruction.

The description or mention of any site,however, should not be taken as an indicationthat access to a site is open or that a right of wayexists. Most sites described in a GeologicalConservation Review volume, for example, arein private ownership, and publication of theirdescriptions is for the purpose of justifying theirSSSI status.

FFiigguurree 4411.. Pitch Coppice,Mortimer Forest, near Ludlow,Herefordshire, is officiallyrecognised by the Inter-nationalUnion of Geological Sciences(IUGS) as the global referencesite used to define the base of theGorstian Stage of the SilurianPeriod. Typical fossils are usedto compare this sequence ofrock layers with rockscontaining the same fossils inother parts of the world,establishing those too asGorstian in age.

This stratotype site formspart of a geological trailmanaged by Forest Enterprise.Vegetation is controlled, and thesite remains accessible all year round to visiting scientists, educational groups and interested members of thepublic. The photograph shows visiting delegates of the Malvern International Conference on Geological andLandscape Conservation (1993). Photo: K. N. Page.

The second component — exceptional features

47

FFiigguurree 4422.. ((aa)) Aerial view ofWenlock Edge, Shropshire,looking north-eastwardstowards Hope Dale (to the rightof the photograph). Theescarpment is formed mainly bythe Farley Member beds cappedby the Much Wenlock LimestoneFormation. Photo: CambridgeUniversity Collection.Reproduced by permission of theCurator of Aerial Photography.

((bb)) Section of Silurian reef limestones of WenlockEdge. Wenlock Edge is one of the classic areas ofBritish geology and formed part of the Wenlock typearea defined by Sir Roderick Murchison in the firsthalf of the nineteenth century. The detailedstratigraphy has since been investigated andrevised. Today it is the designated type area for theMuch Wenlock Limestone Formation and it formspart of the international type area for the WenlockSeries.

Many of the disused limestone quarry facesbacking onto Wenlock Edge are now buriedbeneath extensive earth buttresses constructed toreduce the risk of rock collapse, but sections are stillavailable for study. Photo: M. J. Harley.

❏ type localities for biozones (rock stratawhich are characterised by a closely definedfossil content, usually a fossil species) andchronozones (rock strata formed during thetime-span of the relevant stratotypes)(Figure 42)

❏ internationally significant type localities forparticular rock types, mineral or fossilspecies (e.g. the fossil reptile Megalosaurusfrom Stonesfield in the Cotswolds, Figure43), and outstanding landform examplessuch as Chesil Beach (see Figure 45)

❏ historically important type localities whererock or time units were first described orcharacterised, or where great advances ingeological theory were first made (e.g.

Hutton’s Unconformity at Siccar Point,Berwickshire (see Figure 37)

❏ important localities where geological orgeomorphological phenomena were firstrecognised and described, or where aprinciple or concept was first conceived ordemonstrated (e.g. cauldron subsidence atGlencoe; Figure 44).

THE SECOND COMPONENT —EXCEPTIONAL FEATURES

Many sites have unique, rare or specialfeatures (Figure 45). For example, atRhynie in Scotland, a mineralised peat, in

the form of a siliceous rock called chert (Figure


48

FFiigguurree 4433.. Type specimen ofMegalosaurus bucklandiMeyer, 1832. Partial lowerjaw. Stonesfield is the mostimportant of the BritishBathonian localities in theCotswolds, and arguably thebest Middle Jurassicterrestrial reptile site in theworld. Its fauna is diverseand abundant, and consistsof more than 15 species offossil reptile, includingturtles, crocodilians,pterosaurs, dinosaurs andrare marine forms(ichthyosaurs, plesiosaurs),as well as mammal-likereptiles and mammals. Stonesfield is the most important site in the world for remains of Megalosaurus. Ityielded the ‘type’ material in the early nineteenth century, and continued to produce hundreds of specimens whilethe mines were in operation. Diagram after Buckland (1824).

FFiigguurree 4444.. Glencoe,Lochaber. Thisdramatic glaciated glenhas particularhistorical significanceas the place where‘cauldron subsidence’was first recognised in1909. Volcanologistshad long beenintrigued by certaincollapse features ofvolcanoes and manyworkers had beenactively seeking toexplain their origin.

It was an officer ofthe Scottish GeologicalSurvey, Edward Bailey,who, within days ofvisiting Glencoe, attributed the beautifully exposed collapse features to a mechanism he termed cauldronsubsidence. Bailey was so excited about his findings that he travelled directly to the Geological Society inLondon and made an impromptu presentation about the Glencoe rocks.

Evidence for cauldron subsidence is now preserved in five localities within the SSSI. As Glencoe was thefirst example of this phenomenon to be described in any detail, it serves as the type example throughout theworld.

Recent research, mostly concerned with establishing links between the sequence of volcanic eruptions atthe surface and the development of igneous intrusions deep in the Earth’s crust, has further reinforcedinterest in the area and its international importance. Photo: P. A. MacDonald.

46), of Devonian age, preserves a detailed recordof an early land ecosystem. The exceptionalmicroscopic detail preserved in the Rhynie fossilsmakes this site quite exceptional. No other sitesare known in Britain to contain such well-preserved material of this age. This makes Rhynieirreplaceable. The inclusion of exceptional sitesensures that the highlights of British geology andgeomorphology are conserved.

Exceptional sites may be visually striking andcan contribute dramatically to the character of thelandscape, for instance, Haytor Rocks on Dartmoor(see Figure 1), Cheddar Gorge, Somerset, andChesil Beach, Dorset. In contrast, theunremarkable appearance of East Kirkton Quarrybelies the extraordinary character of the fossilassemblage it contains (see Figure 27).

THE THIRD COMPONENT — REPRESENTATIVENESS

Important though international and exceptionalsites are, they cannot provide the basis for asystematic approach to the selection of sites to

cover the essential features of the Earth heritage ofBritain. This is provided by the selection of sites

representative of features, events and processesthat are fundamental to our understanding of thegeological history of Britain. The starting point ofthe review was to create subject ‘blocks’ whichprovided an overall structure for site selection (thelist of blocks can be found at the end of thischapter). This ensured that the different themes ofEarth science would receive comparabletreatment. The second stage in this approach wasto consider the characteristic features of eachblock and to select representative sites. Withinindividual blocks, sites fall into natural groupingsbased upon geological features or scenarios. Thesegroups are now referred to as networks and theremay be one or more networks in any block.

GEOLOGICAL CONSERVATIONREVIEW BLOCKS

Many of the Geological ConservationReview blocks correspond to the standarddivisions of geological time or to major

events within those periods. They can be groupedinto seven broad categories:

Geological Conservation Review blocks

49

FFiigguurree 4455.. Chesil Beach,Dorset, is a site of inter-national importance for theimpressive and exceptionalsize of its storm beach, thesystematic sorting by size ofthe cobbles and pebbles alongthe shore, and the availabilityof historical records of beachchanges. It is an active coastalgeomorphological site.Together with Orfordness andDungeness, it is one of onlythree major shingle structureson the coast of England.

The 29-kilometre shinglebeach is joined to themainland at the eastern andwestern ends, but for 13kilometres it is backed by the Fleet, a shallow brackish lagoon. The pebble beach consists almost entirely (98%) offlint derived from the Chalk. The remainder is composed of chert and quartzite (both resistant rocks) derived fromoutside the region. The precursor of Chesil Beach probably existed some 125,000 years ago as a shingle bank welloffshore from the present beach. The formation of the present Chesil Beach took place between about 15,000 and5000 years ago, when rapidly rising sea levels caused the erosion of gravel-rich deposits and wave action drove thecoarse material onshore as a barrier beach. Photograph reproduced by permission of the Director, BritishGeological Survey. NERC copyright reserved.

❏ stratigraphy (35 blocks)❏ palaeontology (16 blocks)❏ Quaternary geology (16 blocks)❏ geomorphology: the landforms and

processes that form the current landscape(10 blocks)

❏ igneous petrology (6 blocks)❏ structural and metamorphic geology (10

blocks)❏ mineralogy (7 blocks)

Stratigraphy blocks

For the most part, these blocks are classifiedaccording either to their stratigraphical age(stage, period) or to a range of stratigraphical

ages (e.g. Caradoc–Ashgill Block). Blocks for somestratigraphical ages, however, were defined notpurely by age, but also by geographical area orenvironmental setting where there were significantvariations in the rocks across Britain formed at the

FFiigguurree 4466.. Rhynie Chert. The site atRhynie in Scotland is visuallyunimpressive, and may seem anunlikely geological location, but it isone of the most importantpalaeontological sites in GreatBritain and the world. The Rhyniesite contains some of the finestpreserved and earliest land plants(Devonian) in the world. It alsocontains the earliest-knownwingless insect (Rhyniella) and oneof the finest Devonian micro-arthropod faunas in the world,including mites, springtails and a

small aquatic shrimp-likeorganism, Lepidocaris.

The fossils are preserved inchert. The deposit is anexcellent example of the freakpreservation of life resultingfrom the flooding of a marshsurface on which these plantswere growing, by silica-richwater originating from a hotspring. The hot water killedand preserved the plants andanimals before their tissuesdecayed, and so preserved acomplete ecosystem.

The arthropods found inthe deposit are all primitive

forms, and show an early association between plants and their parasites. Preservation is so good that microscopicdamage to the plants by these arthropods is seen, as are invading fungal hyphae. The plants are preserved so wellthat thin sections of rock can be sliced, and examined under a microscope, to reveal the cell structure, includingthe minute detail of spores as well as cell xylem and stomata.

The photographs show a sample and thin section of the chert. The thin section shows the mouthparts of apalaeocharinid (a spider-like arthropod). Photos: C. C. J. MacFadyen (chert sample) and N. H. Trewin (thin section).


50

same time. This is why there are two blocks for theDevonian Period, one for marine rocks and one fornon-marine rocks.

It is not possible in every case to define blocksby stratigraphical age. For example, where fossilsare rare or absent it is difficult to locate theboundary between different geological ages. Suchstratigraphical units are named after thegeographical localities where they were defined,for example, the Wealden Group consists ofmudstone, shale and sandstone that only occur insouth-east England.

Most invertebrate fossils (e.g. trilobites,echinoderms, ammonites and other molluscs) arealso addressed within the stratigraphy blocks, sincethese fossils are widely used in correlating rockstrata. Because of the relative rarity of fossils suchas reptiles, fish, mammals, birds, terrestrial plants,insects and other arthropods (excluding trilobites),these are covered in separate palaeontologyblocks.

Palaeontology blocks

These blocks address the evolution anddiversity of significant animal and plantgroups not included in the stratigraphy

blocks (see above) and therefore have independentblock status. Geological time is used as the basis todefine some blocks, for example,Jurassic–Cretaceous Reptilia.

Quaternary blocks

The Quaternary blocks are classified on aregional basis, although the subdivision oftime (usually stratigraphical age) is an

important factor. Sites were selected to representthe stratigraphy of Quaternary successions and thedevelopment of landforms.

During the Quaternary Period, northern Britainwas covered by a succession of ice sheets, whilesouthernmost Britain was not glaciated, althoughfrozen ground conditions were experienced. Thewide variation of stratigraphical units andgeomorphological features across Britain, and thelarge number of sites available for study, required thata topic classification for networks within theseblocks was adopted. Three principal themes formthe basis of the Geological Conservation ReviewQuaternary site selection:

❏ environmental history and change based onthe stratigraphy at different localities, age andfossil content, e.g. glacial-interglacial history,sea-level changes

❏ processes and patterns of landscape evolution, e.g. glaciation, periglaciation

❏ the history and development of the floraand fauna, e.g. vegetation history, evolutionof vertebrates.

Comparisons were made between the regionalQuaternary blocks to ensure that certain categoriesof site were not over-represented.

Geomorphology blocks

Geomorphology blocks cover the history anddevelopment of landforms andgeomorphological processes active today,

for example, rivers, coasts and landslides. Unlikegeological sites where processes can only beinferred, active geomorphological sites provideopen-air laboratories where processes can bestudied.

Because geomorphology influences landscapeand habitat, there is great potential for integratingthe physical and biological components of natureconservation in geomorphological sites.

Igneous petrology and structural andmetamorphic geology blocks

The igneous petrology and structural andmetamorphic geology blocks relate to theeffects of mountain building activity, such as

the Caledonian Orogeny.Major episodes of igneous activity form the basis

of six igneous Geological Conservation Reviewblocks, and these are linked to mountain building(e.g. South-west England Igneous), and the openingof oceans (e.g. Tertiary Igneous).

Structural blocks relate to the deformationprocesses during three major mountain buildingepisodes (e.g. the Caledonian, Variscan and Alpineorogenies) and their variation across Britain. Theseblocks include geological features such as folds andfaults, and other effects resulting from compressionaland tensional forces acting within the crust of theEarth.

Four blocks relate to Precambrian rocks inScotland: the Lewisian, Torridonian, Moine andDalradian Blocks. Three of these, the Lewisian,Moine and Dalradian Blocks, have been deformedand metamorphosed during mountain building.

Igneous petrology and structural and metamorphic geology blocks

51

Mineralogy blocks

These blocks address the minerals producedas the result of igneous, metamorphic orsedimentary processes.

GEOLOGICAL CONSERVATIONREVIEW NETWORKS

Because the concept of the network isfundamental to the methods of theGeological Conservation Review, it is

illustrated in some detail in this chapter bydescribing the actual networks adopted inGeological Conservation Review blocks. To aidunderstanding, the networks described here havebeen simplified to some degree, but they indicatethe overall approach taken.

MARINE PERMIAN GEOLOGICALCONSERVATION REVIEW BLOCK

Durham Province network: thewestern edge of an inland sea

Figure 47a is an artist’s impression of a satelliteview of the ‘British Isles’ as they would havelooked some 250 million years ago, towards

the end of the Permian Period. The climate wasarid, much like the Sahara and Arabian Gulf regions


52

FFiigguurree 4477.. ((aa)) Thepalaeogeography of Britainduring the late Permianapproximately 250 millionyears ago — an artist’simpression of a satelliteview. The outline of thepresent-day coastline ofBritain is shown as a dottedline. Much of ‘Britain’ wasdesert, with a large inlandsea to the east, and a smallerone to the west of the what isnow the Pennines, possiblyboth connected by a sea-wayto an open ocean to thenorth of ‘Norway’ and‘Greenland’. Reproducedfrom F.W. Dunning et al.(1978) by permission of theNatural History Museum,London. ((bb)) The extent ofthe late Permian inland sea(the Zechstein Sea). AfterSmith (1995).

a

b

of the present day. Mountainous areas in what isnow southern England and Wales had only recently(in geological terms) been uplifted during theVariscan Orogeny, and remnants of the earlierCaledonian mountains persisted in Scotland. Muchof the present-day area of the North Sea wasoccupied by an inland sea (the Zechstein Sea, namedafter thick Permian rocks deposited in this sea to theeast in northern Germany and Poland) which wasprobably linked to an open ocean to the norththrough a narrow sea-way between ‘Norway’ and‘Greenland’ (Figure 47b). Sediments accumulatedon the western margin of this sea, and those in aneven smaller inland sea to the west of what is nowthe Pennines are referred to as the Marine Permian.One volume of the Geological Conservation Reviewis devoted to them (Smith, 1995).

When the level of the Zechstein Sea wasrelatively high, reefs and shallow-water sand banksfringed its margins (Figure 48a). The reefs and banksformed limestone deposits (calcium carbonate), butwere altered to dolomite (calcium-magnesiumcarbonate) soon after deposition. Their outcropforms a north–south strip across County Durham,Yorkshire and Nottinghamshire, with small outcropsin Cumbria. When the sea level dropped, it seemsthat the link with the open ocean to the north wassevered or reduced, so that evaporation caused thesalinity of the Zechstein Sea to increase. Thisresulted in the deposition of evaporite minerals suchas halite (sodium chloride — common salt) andanhydrite (calcium sulphate), seaward of the earlierlimestone deposits (Figure 48b).

Five episodes of sea-level highs and lows havebeen recognised in deposits laid down beneath theZechstein Sea. These are referred to as ZechsteinCycles, and can be traced from north-east Englandand under the North Sea into Germany and Poland.Only evidence for the first two and the beginning of

the third is exposed at the surface in the CountyDurham area. Figure 48c is a west to east cross-section of the area showing the rock units depositedduring cycles 1 and 2 and the base of 3. Note thatthe rock formations composed of evaporite mineralsare only known from boreholes to the east of strataexposed at the surface, and are represented at thesurface only by the thin residues left after the solubleminerals were dissolved away. The Ford Formationwithin the first Zechstein Cycle (Figure 48d) isparticularly important, as it contains evidence for thedevelopment of a reef that fringed the Zechstein Sea.This was not a coral reef. The most abundant fossilsfound within it are bryozoans (small colonialorganisms that build calcareous skeletons) that actedas sediment baffles which trapped the muddylimestone sediments to build the reef edifice. Thesediments probably became rapidly hardened(lithified) due to the action of cyano-bacteria and theformation of inorganic carbonate minerals whichcemented them, and so would have been able towithstand wave action. However, storm waveswould have broken up the reef edge, so that a slopeof reef debris built up in front of the reef. Anidealised section across the reef and the location ofthe reef crest are shown in Figure 48d.

Figures 48c and 48d encapsulate the theoreticalframework for which sites were selected thatillustrate the key geological features of the marinePermian of County Durham. Ideally, sites illustratingall the environmental settings shown in Figures 48aand 48b should be selected for the network.However, it is impossible to find sites showingsediments composed of the evaporite mineralsanhydrite and halite at the surface because theseminerals are dissolved away. However, sitesshowing the residues left behind have beenselected. The development of a reef of a type verydifferent from those known today adds an extrapalaeontological dimension to the theoreticalframework, requiring the selection of sites showingsuccessive stages in the growth of the structure.The stratigraphical locations of the sites selected forthe Marine Permian Durham Province network areshown in Figures 48c and 48d. Their geographicallocations are shown in Figure 49.

Yorkshire Province network

The Yorkshire Province lies to the south ofthe Cleveland High. The rocks exposed hereare the shallow-water shelf deposits grading

eastwards (over a distance of about 30 kilometres)into finer-grained carbonates. The Yorkshire

Marine Permian Geological Conservation Review Block

53

GGEEOOLLOOGGIICCAALL CCOONNSSEERRVVAATTIIOONNRREEVVIIEEWW NNEETTWWOORRKKSS

Two networks represent the MarinePermian Block of Britain:

● Durham Province network (worked example given)

● Yorkshire Province network.


54

��

��

FFiigguurree 4488.. Rises and falls of the Zechstein Sea and the resultant rock succession in County Durham.((aa)) Deposition of limestone shelves, fringed by reefs, occurred during relative sea-level highs. ((bb)) When therelative sea level dropped, the inland sea was probably partially cut off from the open ocean to the north, so thatevaporation raised its salinity resulting in the deposition of evaporite minerals. ((cc)) West to east cross-sectionshowing the distribution of the dolomitised limestone and evaporite formations (and their residues resultingfrom near-surface dissolution). Cycles 1–3 shown on the right side of the diagram relate to the successive periodsof high and low sea level depicted in (a) and (b) which resulted in dolomitised limestone formations beingoverlain by evaporite formations. The Yellow Sands shown at the base of the diagram were deposited frommigrating desert dunes (similar sands in the southern North Sea are important gas reservoirs). The Marl Slateis a shale rich in organic material that was deposited immediately after the Zechstein Sea flooded the North Seaarea. The numbers indicate the stratigraphical position of sites listed in the table on page 56. ((dd)) Sectionshowing the structure of the reef within the Ford Formation in Cycle 1. Numbers refer to sites listed in the table.

The distribution of Permian Marine rocks in the Durham Province

55

FFiigguurree 4499.. The distribution of Permian marine rocks in the Durham Province, showing the location of the sitesselected for the Geological Conservation Review network for this area. The crest of the Ford Formation reef isshown. After Smith (1995).

Province differs from the Durham Province inthat the barrier carbonate rocks which wereformed near the western edge of the ZechsteinSea during the second main depositional cycle lietoo far east to outcrop onshore. The sites selectedfor the network link together the characteristictypes of sedimentation seen in this lagoonalbackreef environment of the late Permian inYorkshire. The outcrops in this province are

characterised by lagoonal limestone rocks (whichwere later converted to dolomite), together withbryozoan–algal patch-reefs. In the north of theProvince, examples of features not seen in theDurham Province occur, such as marine sabkhadeposits (a sabkha is a wide area of coastal flatsbordering a lagoon where evaporite minerals areformed) and a rare exposure of marineevaporites.


56

MARINE PERMIAN BLOCK: DURHAM PROVINCE NETWORK

SITE NAME GCR SELECTION CRITERIA

1 Trow Point to Whitburn Bay Representative of sedimentation along a marine shallowsea margin and the effects of dissolution of evaporites.

2 Fulwell Hills Quarries Representative of Concretionary Limestone.

3 Hylton Castle Cutting Representative of lower reef-core of the Ford Formation.

4 Claxheugh Rock, Cutting Representative of section through shelf-edge reef and and Ford Quarry backreef strata of the Ford Formation.

5 Dawson’s Plantation Quarry, Penshaw Representative of sediment instability in the lower partof the Raisby Formation.

6 Humbledon Hill Quarry Representative of fauna in the English Zechstein reef.International reference locality for the bryozoanStomatopora voigtiana.

7 Tunstall Hills (North) Representative of shelf-edge reef-core of the FordFormation.

8 (a) Tunstall Hills (South) Representative of shelf-edge reef-core and talus of theand (b) Ryhope Cutting Ford Formation.

9 Gilleylaw Plantation Quarry Representative of patch-reef and reef-margin sediments of the Ford Formation.

10 Seaham Representative of strata of the Seaham Formation and Seaham Residue.

11 Stony Cut, Cold Hesledon Representative of reef flat to reef crest in the FordFormation.

12 High Moorsley Quarry Representative of the Magnesian Limestone of the lower part of the Raisby Formation.

13 Hawthorn Quarry Representative of reef flat of the Ford Formation,Hesleden Dene Stromatolite Biostrome and the overlyingRoker Dolomite.

14 Horden Quarry Representative of crest of shelf-edge reef of the FordFormation.

15 Blackhalls Rocks Representative of the Hesleden Dene StromatoliteBiostrome.

16 Trimdon Grange Quarry Representative of backreef lagoonal sediments of theFord Formation.

17 Raisby Quarries Representative of the Raisby Formation.

IGNEOUS ROCKS OF SOUTH-WESTENGLAND GEOLOGICALCONSERVATION REVIEW BLOCK

There have been many periods of igneousactivity during Britain’s geological history,including several during the Precambrian, and

four main episodes since then, during theOrdovician, Devonian, Carboniferous/Permian andTertiary periods. Such activity is commonly linked tolarge-scale movements of the Earth’s crust and theresultant plate tectonic activity, as described inChapter 3.

In those cases where the igneous processes areassociated with large-scale crustal movementsculminating in the growth of a mountain chain, atleast three phases of activity can commonly beidentified (Figure 50). The earliest events areassociated with volcanic activity and shallowintrusions of molten rock in and around basinswhere sediments accumulate (Figure 50a). Theresulting igneous rocks then become affected bymountain-building processes, and are deformed andoccasionally metamorphosed. The second phase ofactivity involves the generation of large volumes ofgranitic magma deep in the crust, which then risethrough the core of the mountain chain to beintruded at higher levels in the crust (Figure 50b).The final phase of igneous activity occurs after the

Igneous Rocks of South-west England GCR Block

57


● Pre-orogenic volcanic network

● Cornubian granite batholith network(worked example given)

● Post-orogenic volcanic network

● Lizard and Start complexes network.

FFiigguurree 5500.. Sequence ofdiagrams showing igneousprocesses associated withlarge-scale crustalmovements culminating inthe growth of a mountainchain. ((aa)) Igneous intrusions andvolcanic rocks prior tomountain building. ((bb)) Generation of magmadeep in the crust, and theformation of batholiths. ((cc)) Minor intrusions —dykes, sills — form at the endof the orogeny (see Figure12).

main tectonic events are over, and generally involvesthe development of volcanic activity and minorigneous intrusions (Figure 50c).

The igneous rocks of south-west England(Figure 51) illustrate the range of complexrelationships which occurred during the threephases described above of the Variscan Orogeny.This Orogeny occurred about 300 million yearsago when south-west England was on thenorthern margin of the mountain-building area(see Figure 17). The core of the mountain chainlay to the south in the Massif Central of France.The sediments which accumulated in south-westEngland in Devonian and Carboniferous timesinclude volcanic rocks, which now provide thebasis of the pre-orogenic volcanic GeologicalConservation Review network. Although theserocks were intensely folded and deformed duringthe orogeny, the amount of metamorphism theyunderwent was low and the rocks have retainedmuch of their original structure. After the rocks

had been folded they were intruded by a largegranitic magma, the characteristics of which areused to create the Cornubian granite batholithGeological Conservation Review network. Thegranite cut through earlier igneous rocks and foldstructures, and so was intruded after the tectonicevent. It can be distinguished from othergranites which occur to the south, in Brittanyand the Massif Central, whose formation wasintimately associated with the mountain-buildingprocess. This is an example of where a potentialnetwork exists, but it is absent from Britain.Following the orogeny, there was a period ofminor volcanic activity represented by the post-orogenic volcanic network. South-west Englandalso includes the metamorphosed igneous rockcomplexes of the Lizard and Start peninsulas.These areas are not directly linked geologically tothe networks outlined previously, but as theyform a geographical unit are included as theLizard and Start complexes network.


58

FFiigguurree 5511.. Simplified geological map of south-west England showing the distribution of igneous rocks and thelocation of Geological Conservation Review sites. Sites of the Cornubian granite batholith network are numberedas in the site list in the text. After Floyd et al. (1993).

Pre-orogenic volcanic network

This network comprises those igneous andvolcanic rocks which accumulated within theDevonian and Carboniferous sediments prior

to the Variscan Orogeny (Figure 51; compare withFigure 50a). The network includes the followinggeological situations:

❏ different forms of igneous intrusive andextrusive process, such as sills and pillowlavas, and the development of areascharacterised by different rock types

❏ variations within individual igneous bodies,including gradations from intrusive toextrusive, and internal zonation in igneousbodies

❏ different relationships between the igneousrock and adjacent sediments

❏ effects of subsequent deformation andmetamorphism

❏ representative examples of different ages ofigneous activity.

Cornubian granite batholith network

This network illustrates the variations withinthe Cornubian batholith which outcrops in aseries of distinct masses such as Dartmoor,

Bodmin Moor and Land’s End (Figure 51).However, these masses are connected deep withinthe crust into a large east–west-trending granitebatholith. The network encompasses the followinggeological situations:

❏ variations in the mineral composition andtexture of different parts of the individualgranite masses reflecting differences in theoriginal magma composition, age,crystallisation history, mode of intrusion andlate-stage changes

❏ relationships between the granite and the countryrocks, including normal contacts, roofpendants (country rock which roofs thebatholith) and xenoliths (fragments of countryrock contained within the batholith)

❏ the nature of late-stage processes associatedwith hydrothermal activity, such as thedevelopment of china clay, greisen (graniticrock affected by the action of chemically richvapours) and mineral veins (the metallogenesisassociated with these granites will be coveredin a separate Geological Conservation Reviewvolume) and

❏ the occurrence of minor intrusions, such as

granite cupolas (dome-like protuberances fromthe main body of the batholith), and aplites (asugary-textured igneous rock) and pegmatites(a coarsely crystalline igneous rock withcrystals three or more centimetres long).

The sites selected for this network are tabulated onpage 60.

The network is further illustrated by Figure 52which places each of the sites on a generic granitebatholith diagram. The figure demonstrates howrelatively few sites have been identified tocharacterise one of the major granitic bodies inBritain for the Geological Conservation Review.

Post-orogenic volcanic network

This network illustrates the different types oflava which erupted into the desertenvironment that existed after the close of the

Variscan Orogeny, in late Carboniferous and Permiantimes, when the granite masses formed high groundthat was undergoing active erosion.

Post-orogenic volcanic network

59

FFiigguurree 5522.. Schematic diagram of the Cornubiangranite batholith. The numbers refer to the sitesdescribed in the table on page 60.


60

IGNEOUS ROCKS OF SOUTH-WEST ENGLAND BLOCK: CORNUBIANGRANITE BATHOLITH NETWORK


1 Haytor Rocks Area Representative of the coarsely-crystalline Dartmoor Granite.

2 Birch Tor Representative of a suite of rocks included within the granite (xenoliths).

3 De Lank Quarries Representative of coarse-grained Bodmin Moor Granite with xenoliths and dykes.

4 Luxulyan Quarry Representative of coarse granite formed early in the sequence at St Austell. ‘Internationally renowned’ for in situ occurrence of the British rock type luxullianite.

5 Leusdon Common Representative of the complex relationships between granite intrusion and country rocks.

6 Burrator Quarries Representative of the contact between the granite and the Devonian sediments. ‘Internationally renowned’ as a site where the contact of the granite can be seen.

7 Rinsey Cove (Porthcew) Representative of the upper part of the granite intrusion.

8 Cape Cornwall area Representative of the contact between the Land’s End Granite and the country rock.

9 Porthmeor Cove Representative of two small satellites of the Land’s End Granite.

10 Wheal Martyn Representative of the granite which provides the source of the china clay.

11 Carn Grey Rock and Quarry Representative of granite intermediate in type between the two at St Austell.

12 Tregargus Quarry Representative of variants of the St Austell Granite.

13 St Mewan Beacon Representative of a rare rock type formed in the rocks roofing the granite.

14 Roche Rock Representative of a rare rock rich in the mineral tourmaline.

15 Megiliggar Rocks Representative of a complex contact between the granite and baked country rock.

16 Meldon Aplite Quarries Representative of a large fine-grained dyke formed at a late stage in the development of the granite. ‘Internationally renowned’ for its unusual minerals.

17 Praa Sands (Folly Rocks) Representative of a multiple granitic dyke.

18 Cameron (Beacon) Quarry Representative of the contact of the St Agnes Granite with its country rock.

19 Cligga Head area Representative of minerals created in the country rock by a small granite body, and their process of formation.

The network illustrates the following geologicalsituations:❏ the considerable variations in mineralogy

and rock type between different localities,some rock types being relatively unusual

❏ the nature of the relationships between theigneous rock and the adjacent sediments.

Lizard and Start complexes network

These complexes represent the remnant of anancient sea floor which has beensignificantly metamorphosed and deformed

to the point that interpretation is difficult and canbe controversial. The network illustrates thecomplicated geological history to which theserocks have been subjected, encompassing thefollowing geological situations:

❏ variations in ocean-crust rocks such asbasalt, gabbro and peridotite

❏ the presence of gneiss and schist associatedwith multiple deformation phases

❏ the range of occurrence of igneous bodiessuch as pillow lavas and dykes

❏ complex contacts between rock types ofdifferent age and origin

❏ the influence of metamorphism.

PALAEOZOIC PALAEOBOTANYGEOLOGICAL CONSERVATIONREVIEW BLOCK

At the beginning of the Palaeozoic Era, single-cell plants had existed for over 3000 millionyears but had probably been restricted to

aqueous, mainly marine, environments. Plants hadevolved in the seas and were adapted to anenvironment which supported their tissues, bathedthem in nutrients, contained dissolved gases forrespiration and photosynthesis, and allowed, in those

plants which employed sexual reproduction, themale gametes to swim to the ova. For such plants theland was a hostile environment. ‘Soils’ were sparseand poor in nutrients. Photosynthesis and respirationhad to take place in the air where the environmentwas dry. The air provided no support for above-ground vegetation and, away from damp ground, themale gametes were unable to swim to the ova. But,by the end of the Palaeozoic Era, plants haddeveloped features that would enable them toovercome all these problems.

To succeed on land, plants required (1) water-resistant surface tissues (cuticle) and spores, (2)strengthening mechanisms to support the weight oftheir aerial tissues, (3) a means of conveying waterand nutrients from the soil to the aerial tissues, aswell as oxygen and the products of photosynthesisback to the roots, and (4) the means of fertilising ovain dry conditions.

By the end of the Silurian Period, the first vascularplants had developed which combined moisture-resistant surface tissues and spores with thedevelopment of strengthening and water-conductingstructures within the stems. These developmentscontinued in the Devonian Period with theappearance of secondary wood and an increasingsophistication of the other structures. By the lateDevonian, the first seed plants (gymnosperms)appeared, together with tree-like roots. In theCarboniferous, pteridophyte forests (tree ferns andgiant club-mosses up to 40 metres high) dominatedthe equatorial delta areas, and the main classes ofseed plants evolved. In ‘Europe’ and ‘NorthAmerica’, the drier conditions of the Permian saw thepteridophyte forests in decline and the proliferationof the seed plants.

These changes took place during the PalaeozoicEra over a period of 200 million years. TheGeological Conservation Review treats the topic byselecting sites on the basis of five networks: Silurian,Devonian, Lower Carboniferous, UpperCarboniferous and Permian. Evolutionary networksare an example of networks where there may begaps in the site record. Plants existed, and may havebeen fossilised, which show all the stages in theevolutionary development, but some of these haveyet to be found. An example of a network in thePalaeozoic Palaeobotany Block is the Siluriannetwork.

Silurian network

This network represents the different types offossil plant from the Silurian Period (rangingfrom 445 to 395 million years ago). Britain has

Palaeozoic Palaeobotany GCR Block

61


● Silurian network (worked example given)

● Devonian network

● Lower Carboniferous network

● Upper Carboniferous network

● Permian network.

the most complete known record of Silurian landplants in the world. Most of the sites are in Wales andthe Welsh Borders. The climate in which these plantsgrew was tropical and the conditions humid, warmand equable — highly suited to the colonisation ofthe land by plants.

Marine algae (seaweeds) existed throughout thePalaeozoic Era and vascular plants are believed tohave evolved from the green algae group, perhapsfrom an ancestor shared with the stoneworts, agroup characteristic of freshwater habitats. Aspectacular early non-vascular terrestrial plant wasPrototaxites which had thick ‘trunks’ that layprostrate on the land surface and were constructedof a mass of tubes which may have functioned likevascular tissue. Another land plant,Nematothallus, was probably an encrusting plant,where the tissue was not differentiated into leaves,stems or roots. However, the most significant ofthe Silurian plants were small with simple stemsbranching into two, known as rhyniophytoids,including Cooksonia and Steganotheca. These aregenerally considered to have included the earliestvascular plants, and examples of slender axes(albeit without the characteristic spore-bearingbodies) with true vascular tissue are reported from

the Ludlow Series. Gas and water exchange waspossible through surface cells called stomata,which opened or closed to control this exchange.

The network can be illustrated diagrammaticallyon the basis of the presence of adaptive structuresfor life on land. Figure 53 demonstrates thisconcept, showing where the selected sites fit intothe network.

During the succeeding periods of thePalaeozoic, the evolution of features adapted to lifeon land continued and all the main classes of plants,except the flowering plants appeared. For most ofthis period the climate continued to be tropicaland, in the diverse swamp forest communities,plants competed for space and light, encouragingthe development of tall stems and frond-like foliage.Towards the end of the Palaeozoic era, drierconditions favoured adaptations less dependent onmoist conditions. The features of the fourremaining networks are summarised below.

Devonian network

By the end of the Devonian all the major groupsof vascular plants were present except theflowering plants. Important characteristics of

the Devonian network are:

PALAEOZOIC PALAEOBOTANY BLOCK: SILURIAN NETWORK


1 Pen-y-Glog Quarry, Clwyd Representative of early land plants in the Silurian Period, theoldest known in Britain, including examples of Prototaxites.Preserves the oldest-known terrestrial plant cell structures inthe world.

2 Llangammarch Wells Quarry, Representative of Silurian marine plants, including the non-Powys calcareous alga Powysia.

3 Rockhall Quarry, Representative of Silurian marine plants, particularly the alga Hereford and Worcester Inopinatella.

4 Cwm Craig Ddu Quarry, Powys Representative of early Silurian land plants, and has yielded theoldest specimens of Cooksonia in Britain and one of the oldestrecords of Cooksonia in the world.

5 Capel Horeb Quarry, Powys Representative of early land plants, including Nematothallus,Cooksonia and Steganotheca. Contains the oldest-knownplants with vascular tissue in the world.

6 Perton Lane, Representative of the earliest land vegetation. Central to any Hereford and Worcester discussion of early land ecosystems. The type locality for

Cooksonia.

7 Freshwater East, Dyfed Representative of the diversity of the early land flora. Themost diverse land flora of Silurian age in the world, and hasyielded the oldest known examples of spiny axes.


62

❏ the evolution of plant structures, includinglaminate foliage, seeds, secondary wood andtree-like forms up to 20 metres high

❏ the development of major plant groups,including clubmosses, horsetails, fern-likeplants and seed plants

❏ colonisation of upland areas away from wetbasins

❏ ecologically important plant assemblagesreflecting various environmental conditions.

Lower Carboniferous network

The Lower Carboniferous saw few reallysignificant structural developments in plants; itwas a time of consolidation of the

developments that had taken place in the DevonianPeriod. However, seed plants diversified and a groupcalled pteridosperms, which had fern-like fronds,produced seeds and often grew to tree size.Important characteristics of the Lower Carboniferousnetwork were:

❏ the diversification of early ferns and fern-likeplants, clubmosses, horsetails and seed plants

❏ the development of the earliest extensiveforest habitats


Upper Carboniferous network

While evolutionary advances took place inthe tropical uplands (e.g. the appearanceof conifers) and at higher latitudes, the

plant fossils of the tropical lowland habitats are ofinterest primarily because they reflect the high pointof forest vegetation dominated by clubmosses up to

40 metres high and, towards the end of the period,by tree-ferns, pteridosperms and cordaites, a conifer-like group. The productivity of these forests isreflected in the fact that this was the main period ofdeposition or organic material that became coal.Important characteristics of the Upper Carboniferousnetwork are:

❏ the diversification of earlier forms, includingferns and seed plants

❏ the development of adaptations assistinggrowth in drier areas, including seed plants

❏ diversity of the plant communities of thelowland swamp forests


Permian network

The increasingly arid conditions during thePermian Period in ‘Britain’ caused theextinction of the Carboniferous swamp-forest

vegetation dominated by clubmosses and horsetails,and their replacement by ferns and seed plants,particularly conifers. There are few good Permiansites in Britain that contain plant fossils. Thenetwork’s important characteristic is to demonstratethe changing nature of forest communities facingconditions of increasing aridity.

QUATERNARY GEOLOGICALCONSERVATION REVIEW NETWORKS:ENGLISH LOWLAND VALLEY RIVERS

The geological history of the Quaternary Periodin the major valleys of southern England is thesame as their geomorphological history. The

Quaternary GCR networks

63

FFiigguurree 5533.. Schematicdiagram showing theevolution of structuresthat are necessary forplants to survive onland. The numbers referto the sites described inthe table on page 62.

Alluvium Holocene 1 5000Shepperton Gravel Devensian 5d-2(river down-cutting — buried channel)East Tilbury Marshes Gravel

Interglacial deposits at Ipswichian 5e 125,000Trafalgar Square

Spring Gardens Gravels unnamed 6(river down-cutting)Mucking Gravel (late)

Interglacial deposits unnamed 7 215,000at Aveley

Mucking Gravel (early) unnamed 8(river down-cutting)Corbets Tey Gravel (late)

Interglacial deposits at Hoxnian 9 320,000Belhus Park

Corbets Tey Gravel (early) unnamed 10(river down-cutting)Orsett Heath Gravel (late)

Interglacial beds at Swanscombian 11 400,000SwanscombeOrsett Heath Gravel (early) Anglian 12 about 450,000Dartford Heath GravelHornchurch Till (glacial deposits)

evidence consists of old river gravels preserved atdifferent elevations in the valleys as river terraces.They increase in age with increasing height abovethe present floodplains. As such, they form a‘staircase’, each step consisting of a gravel terrace,the top of which approximately represents theremains of an ancient floodplain surface. They havebeen preserved as a series of steps because the rivershave cut vertically downwards in response to

climatic change and uplift of the land.This unique relationship between geological

deposit and landform is an invaluable opportunity toexplore and understand the geological andgeomorphological development of lowland Englandand the way in which it responded to climatic changes.Its importance is enhanced further because the laterstages of terrace development coincided with theearliest human occupation of the British Isles. Hand

Geological deposit(or event)Compare with Figure 54

Britishstage

Oxygen isotope stage

Age in yearsbefore present

Lower ThamesQuaternary GeologicalConservation Review sites(Bridgland, 1994)

Purfleet–Bluelands,Greenlands, Esso andBotany Pits

Globe Pit, Little Thurrock

Swanscombe

Wansunt Pit, Hornchurch RailwayCutting

Ages, in thousands of years at the mid-point of the stage, are given. Note that some gravel deposits (e.g. theMucking Gravel) accumulated over three stages. Italics show sites where the age has been established by amino-acid dating of protein in fossil shells. This table should be compared with Figure 54.


64

Northfleet (Ebbsfleet Valley):Baker’s Hole Complex;Aveley, Sandy Lane QuarryLion Pit Tramway Cutting

Table 2. Each row represents a period of time, where stages with odd numbers correspond to interglacials,and even numbers to ice ages.

axes fashioned by prehistoric people are often foundwithin the old river gravels. Thus the geologicalhistory, landform (geomorphological) history, andprehistory and archaeology are related by the contentsof the Quaternary sediments and the landforms theycomprise.

The remains of these river gravels which weredeposited throughout southern England, for example,in the Thames, Avon and Severn valleys, are the basisfor several Geological Conservation Review networks.The older the gravel deposits, the less likely they are tohave been preserved, and many site ‘gaps’ exist in thelowland river valley Quaternary networks because theevidence has been destroyed, by either naturalprocesses or gravel extraction.

The Thames Valley is an example of a river

system that has evolved over nearly two millionyears. Three principal phases occurred in itsdevelopment.

1 When the ‘Thames’ flowed between what isnow Reading, Watford, St Albans and Hertford intoEast Anglia and then the North Sea. Early in thisphase its headwaters may have extended into Wales,because igneous rocks from North Wales arecontained in its river gravels. These may have beenintroduced into its headwaters by early Welsh uplandglaciers.2 When a large ice sheet during the Anglianglaciation, some 450,000 years ago, blocked theformerly north-east flowing course of the ‘Thames’and it adopted its present path through what is nowcentral London to the Thames Estuary.3 The development of the Thames since theAnglian glaciation, when extensive river gravels weredeposited along its present-day valley: for example,the Taplow Terrace which forms the widespread‘flat’ areas around Slough and Heathrow Airport.

These three phases are represented by more thanone Geological Conservation Review network, eachof which exemplifies stages in the evolution of theThames Valley. Figure 54 shows a diagrammaticsection of the Lower Thames Valley. Twelve distinctstages are represented here, each one correspondsto a major event in the history of the valley that iscorrelated with a global event as revealed in the

Quaternary GCR networks

65


IINN TTHHEE QQUUAATTEERRNNAARRYY OOFF TTHHEETTHHAAMMEESS BBLLOOCCKK

● The Upper Thames Basin

● The Middle Thames

● The Lower Thames (worked example given)

● Essex.

FFiigguurree 5544.. Diagrammatic section of the Lower Thames Valley. Oxygen isotope stages of interglacial deposits (black)are shown circled. After Bridgland (1994).

oxygen isotope stratigraphy of deep-oceansediments (Table 2). Oxygen isotope stages 1, 5e, 7,9 and 11 correspond to interglacials, when globalice-volume was similar to the present. Stages 2, 3, 4,5, 6, 8, 10 and 12 correspond to ice ages. The agesof the mid-points of the interglacials are shown.These are based on amino-acid dating, which is alsothe basis for correlating the Lower Thames depositswith those elsewhere in Britain.

The first column in Table 2 shows the namedgeological deposits and down-cutting events of theriver. All of the river gravels were deposited in aperiglacial environment, when ice sheets occupiednorthern Britain. Their braided streams had verywide floodplains.

Figure 54 shows the main geomorphologicalterrace features of the Lower Thames. Itscomplicated history may be explored further inTable 2. This complex evolution occurred duringfive major ice ages and five interglacials (includingthe present one).

The degree of natural preservation of the Thamesdeposits varies considerably. The older ones are themost dissected, while those deposited after theAnglian glaciation are relatively better preserved. Allof them, however, have been subject to destructionor modification through natural erosion, as well as byquarrying activities for sand and gravel aggregates.They are still an important and valuable economicresource.

THE COASTAL GEOMORPHOLOGYOF SCOTLAND GEOLOGICALCONSERVATION REVIEW BLOCK

Much of the coastline of Scotland consists ofrelatively old rock types of variableresistance to erosion, ranging from the

ancient, durable Lewisian rocks of the north-westto the younger, less resistant Devonian Old RedSandstone sediments and Carboniferous lavas of theeast. Younger Tertiary lavas, prone to landslidingwhere underlain by weaker sediments, form thecoastline of parts of the Inner Hebrides. Thevariations in hardness and rock structure (jointingand bedding) have a fundamental control on theoverall coastline form and on the shape of thelandforms. In addition, rock structures, such asmajor faults, have played a part in coastline form,most notably in the pattern of sea lochs in westernScotland.

Apart from rock type and structure, factors suchas climate, wind, tide and wave action, the effects

of glaciation and sea-level change, vegetative‘protection’ and the availability of sediment supplyall play a role in shaping the coast, the stability ofthe present coastal environment and the effects ofpresent-day geomorphological processes.

Broadly, the interrelationships between thesefactors make it possible to classify types of coastlineinto beach complexes, rock-coast features andsaltmarshes. The beach complexes can becategorised further into distinctive types for theHighlands and Islands (beach-machair system,beach-dune-machair system, beach-bar system,prograding coastal foreland) and lowland Scotland(beach-dune system, prograding coastal forelandand shingle structures). Similarly, the rock coastand saltmarsh coastlines can be subdivided further.These categories form the basis of GeologicalConservation Review networks.


66


Beach complexes of the Highlands andIslands

● Beach-machair system

● Beach-dune-machair system (worked example given)

● Beach-bar system

● Prograding coastal foreland

Beach complexes of lowland Scotland

● Beach-dune system

● Prograding coastal foreland

● Shingle structures

Rock coast geomorphology

● Cliffs and related features

● Shore platforms

● Archipelago

Saltmarsh geomorphology

● Barrier beach

● Estuary

● Loch head.

Beach complexes of Scotland

Beach complexes are widely distributedthroughout Scotland. Typically they comprisebeaches, sand dunes, machair (dune pasture

with lime-rich soils), links or some combination ofthese. In the north and west, and particularly in theOuter Hebrides and Shetland, they are associatedwith high-energy, exposed environments; in thesouth and east, lower levels of energy and exposureprevail. Modern active shingle structures arerelatively rare, although there are extensive sites ofraised shingle ridges in many areas. In a British

context, the beach complexes of Scotland arenationally important for:

❏ the machairs of the Highlands and Islandswhich are exceptionally rare in westernEurope (some examples occur in north-westIreland)

❏ features associated with high-energy,exposed environments

❏ some of the largest British blown-sandfeatures

❏ some of the most extensive areas of sandcoast progradation

❏ features associated with glaciated coasts.

COASTAL GEOMORPHOLOGY OF SCOTLAND BEACH-DUNE-MACHAIRSYSTEM OF THE HIGHLANDS AND ISLANDS


Central Sanday, Orkney Representative assemblage of beach, dune and machair landformsand processes in an area of coastal submergence; includes anassemblage of tombolos, bars and spits.

Traigh na Berie, Western Isles Representative beach-dune-machair complex notable for its widerange of landforms and processes.

Pabbay, Western Isles Representative of machair and dune surfaces important forinterpreting the development of these features associated withcoastal submergence.

Luskentyre and Corran Representative of a dynamic beach-dune-machair system.

Seilebost, Western Isles Representative of a beach complex developed in a relatively low-energy environment.

Hornish and Lingay Strand/ Representative assemblage of beach-dune-machair features such asMachair Robach and Newton, machair dissection and coastline recession.Western Isles

Ardivachar and Stoneybridge, Internationally important and representative of a wide range ofbeach-dune-machair complexes in a high-energy environmentmodified by a shallow nearshore zone. Imprtant for showinggeomorphological interrelationships between features. Type area formachair landforms and development.

Eoligarry, Western Isles Representative of landforms and processes of dune and machairerosion.

West coast of Jura, Strathclyde Internationally important and representative of raised shorelines, but also includes beach, dune and machair features, notably the

relatively rare cliff-foot type of machair.

Machir Bay, Strathclyde Representative beach-dune-machair complex in a high-energyenvironment. Exceptional for machair ridge and hillside forms andfor showing water-table and drainage controls on machair and dunemorphology.

Dunnet Bay, Highland Representative site for showing the scale of dune and machair landforms and modern-day processes.

The Coastal Geomorphology of Scotland GCR Block

67

Western Isles

Beaches of the Highlands and Islandsnetworks

Sandy beaches comprise less than 5% of thetotal length of the coastline of the Highlandsand Islands. Most of the beaches occur on the

islands on the open, highly exposed Atlanticcoasts, and to a lesser extent in north and eastSutherland. This distribution is related to fourprincipal controlling factors: exposure, relief of thecoastal zone, rock type and glacial history. Manybeaches in the region are associated on thelandward side with blown-sand deposits in theform of sand dunes or machair, forming what arecalled beach complexes. Glaciation has been animportant factor in beach-complex development:first, in providing a source of sediments, andsecond, in influencing changes in sea level overtime and space, which have left a strong imprint.

The beach-complex network illustrated here isthe beach-dune-machair system of the Highlandsand Islands.

Beach-dune-machair system

The beach complexes associated with machairdevelopment are among the most distinctivesoft coast systems of Britain. The Geological

Conservation Review network which addresses thissystem includes all the associated major features(landforms and processes) and encompasses their

history of development and their variationsaccording to the principal controlling factors. Thisnetwork is shown diagrammatically in Figure 55.

Twelve sites were selected for this network toillustrate the features of the beach-dune-machairsystem, with preference being given to those sitesthat show outstanding examples of landforms orlandform assemblages in the beach-dune machairsystem and sites that offer opportunities toelucidate the links between landforms and theprocesses which form them as well as the historyof their development. Emphasis was placed onselecting sites with assemblages of features. Theimportance of each site is summarised in the tableon page 67.

Beach and dune coasts of lowlandScotland networks

Sandy beaches form a relatively large part of thecoastline of lowland Scotland, notably on theeast coast. This reflects the less indented

nature of the coastline in comparison with that ofthe Highlands and Islands, and the reworking oflarge volumes of sediment which had beendeposited on the continental shelf duringdeglaciation. Larger beaches are typically long andcurved with a single dune line, and extensive linksare developed on older low raised beaches. Thebeach and dune coasts of lowland Scotland can begrouped into three models:


68

FFiigguurree 5555.. The beach-dune-machair network addresses the variations in landforms and processes which occurin the Highlands and Islands area affecting this type of beach complex. The network covers the range anddiversity of active and relict geomorphological features. Drawing by C. Ellery.

BEACH ROTATION

PREVAILING WIND

DUNE RIDGE

intermittent sediment exchange between dunes,

beach and seabed

wind erosion of dunes forming

blowouts; sand redepositedinland

wind erosion and retreat of

machair escarpments

wind blown sand deposition as hill machair

machair plain

LONGSHORE DRIFT

❏ beach-dune systems with parallel duneridges, illustrating the development ofdifferent dune types and blown-sand deposits

❏ prograding foreland systems, showing thescale, complexity and diversity of thelandforms and processes associated withcoastal progradation, such as stabilised dunesands and dynamic spit and barenvironments

❏ shingle structures showing the assemblageof active and raised shingle ridges andshingle spits.

Rock coast geomorphology networks

Rock coast features are characteristic ofextensive parts of western Scotland fromthe Clyde Estuary to Shetland and including

the north coast of the mainland. They includelarge glaciated sea lochs, low ice-scoured coasts,low cliffs with shore platforms of variable widthand extent, and high cliffs, varying according topatterns of rock type, glacial erosion and isostaticuplift. To the east and south-west, rock coasts aremore intermittent or buried in drift or sandoverlying shore platforms. The rock coast featuresof Scotland are important for

❏ features associated with igneous andmetamorphic rocks

❏ features associated with high-energyexposed environments

❏ some exceptionally high-cliff coast features❏ features associated with glaciated coasts.

Saltmarsh geomorphology networks

Saltmarshes are limited in distribution in Scotlandand are confined to a number of estuary, barrier-beach and loch-head settings. They are importantfor:

❏ features associated with crustal uplift❏ relatively young features that allow

comparisons to be made with moredeveloped systems in England

❏ features associated with loch-headenvironments.

THE GEOLOGICAL CONSERVATIONREVIEW SITE SERIES

The examples described above showsomething of how the network approachdeals with the range of situations and

circumstances that British geology andgeomorphology encompass, and the flexibility ofthe approach in developing a comprehensiveseries of representative sites that illustrate thecharacteristics of each block.

The suite of Geological Conservation Reviewsites is derived from the selection of theinternational, exceptional and representative sitesdiscussed above. Of course, the great majority ofthe internationally important and exceptional siteswere also selected as representative sites becausethey were the best example for portraying anessential characteristic within a relevant block.

The Geological Conservation Review site seriesis summarised in Figure 56. The figure lists theGeological Conservation Review blocks andindicates how these blocks will be grouped forpublishing within the Geological ConservationReview volume series. The numbers anddistribution of sites across Great Britain withinthese volumes are also shown.

The selection of individual sites to representthe essential characteristics of the blocks was amajor element of the work of the GeologicalConservation Review. The methods employed todo this are described in the next chapter.

The Geological Conservation Review site series

69

FFiigguurree 5566.. List of blocks.

Distribution of sitesGCR volume GCR blocks England Scotland Wales

STRATIGRAPHY

Tertiary Paleogene 45Neogene

Upper Cretaceous Cenomanian–Maastrichtian 35 2

Marine Lower Cretaceous Berriasian–Barremian 45Aptian–Albian

Jurassic–Cretaceous Portlandian–Berriasian 72Boundary Interval Wealden

70

Upper Jurassic: Oxfordian 39 5

Oxfordian–Kimmeridgian Kimmeridgian

Middle Jurassic Bathonian 101 13CallovianAalenian–Bajocian

Lower Jurassic Hettangian, Sinemurian, 34 9 2 Pleinsbachian

Toarcian

Permian–Triassic Rhaetian 47 10 6

Permian–Triassic (red beds)

Marine Permian of England Marine Permian 27

Upper Carboniferous Westphalian 82 9 21Namurian (part)

Lower Carboniferous Dinantian of Scotland 89 33 27Dinantian of northern England and North Wales Dinantian of Devon and Cornwall Dinantian of southern England and South WalesNamurian (part)

Devonian Non-marine Devonian 62 22 11Marine Devonian

Silurian Ludlow 63 14 36WenlockLlandovery

Cambrian–Ordovician Caradoc–Ashgill 35 18 71LlandeiloArenig–LlanvirnArenig–Tremadoc and Cambrian–Tremadoc TremadocCambrian

Precambrian of England Precambrian of England 21 13and Wales and Wales+

Precambrian Palaeontology

STRUCTURAL AND METAMORPHIC GEOLOGY

Moine, Torridonian and Moine+ 111Lewisian Torridonian+

Lewisian+

Dalradian Dalradian+ 73

Variscan to Alpine Variscan Structures of 42 14Structures South Wales and the

Mendips Variscan Structures of south-west England Alpine Structures of southern England


71

Caledonian Structures Caledonian Structures 12 9 20of Great Britain of the Lake District

Caledonian Structures of the Southern UplandsCaledonian Structures of Wales

IGNEOUS PETROLOGY

Caledonian Igneous Caledonian Igneous 23 81 26Old Red Sandstone Igneous Ordovician Igneous

Igneous Rocks of South-west England Igneous 54South-west England British Tertiary Tertiary Igneous 2 50Volcanic Province Carboniferous– Carboniferous– 17 31 1Permian Igneous Permian Igneous

MINERALOGY

1. Metallogenesis Mineralogy of the 105 47 22Lake District

2. Mineralogy Mineralogy of the Pennines

Mineralogy of the Mendips Mineralogy of the Peak District/ Leicestershire/ Cheshire/ ShropshireMineralogy of south-west England Mineralogy of Wales Mineralogy of Scotland

PALAEONTOLOGY

Fossil Reptiles of Tertiary Reptilia 43 6 1Great Britain Jurassic–Cretaceous

Reptilia Permian–Triassic Reptilia

Fossil Mammals and Birds Tertiary Mammalia 55 3 10Mesozoic Mammalia Pleistocene Vertebrata Aves

Fossil Arthropods Palaeoentomology 23 11Arthropoda (excluding insects and trilobites)

Fossil Fish Silurian–Devonian 42 40 3Chordata Permian/Carboniferous Fish/Amphibia Mesozoic–Tertiary Fish/Amphibia

Mesozoic Tertiary Tertiary Palaeobotany 46 5 1Palaeobotany Mesozoic PalaeobotanyPalaeozoic Palaeobotany Palaeozoic Palaeobotany 12 19 11of Great Britain


72

QUATERNARY GEOLOGY AND GEOMORPHOLOGY

Quaternary of East Anglia Quaternary of East Anglia 90and the Midlands Quaternary of the Midlands

and Avon Quaternary of eastern England (part: south)

Quaternary of Quaternary of north-east 66Northern England England

Quaternary of Cumbria Quaternary of eastern England (part: north) Quaternary of the Pennines

Quaternary of South and Quaternary of south-east 44South-east England England

Quaternary of south central England

Quaternary of Quaternary of 60South-west England south-west England

Quaternary of Somerset

Quaternary of the Thames Quaternary of the Thames 46

Quaternary of Scotland Quaternary of Scotland 136

Quaternary of Wales Quaternary of Wales 72Tufa*Holocene Sea Levels*Pollen Stratigraphy ofEngland*

GEOMORPHOLOGY

Karst and Caves of Great Britain Caves 72 3 14

Karst

Coastal Geomorphology of Coastal Geomorphology 45 41 13of Scotland Coastal Geomorphology of Wales Coastal Geomorphology of England Saltmarsh Morphology

Fluvial Geomorphology of Fluvial Geomorphology 35 27 19Great Britain of Scotland

Fluvial Geomorphology of EnglandFluvial Geomorphology of Wales

Mass Movement Mass Movement 18 6 3

* Sites will be included in the relevant regional Quaternary volume.+ Includes all metamorphic, tectonic, igneous and stratigraphic features of interest.


Practical Geological Conservation Review

selection methods

Chapter 5

SITE SELECTION CRITERIA

The three essential components of theGeological Conservation Review areexplained in Chapter 4. Practical guidelines

were also developed so that GeologicalConservation Review sites can be selected fromthe range of candidate sites.

First, two operational criteria are employed.

❏ there should be a minimum of duplication ofinterest between sites

❏ it should be possible to conserve any proposedsite in a practical sense.

All scientific factors being equal, sites that cannotbe conserved, or which entirely or largelyduplicate the interest of another, are excluded.Sites that are least vulnerable to potential threat,are more accessible and are not duplicated byother sites are preferred.

Preference is given to sites that:

❏ demonstrate an assemblage of geologicalfeatures or scientific interests

❏ show an extended, or relatively complete,record of the feature of interest. In the case ofgeomorphological sites, this often equates tosites that contain features which have beenleast altered after formation (e.g. KildrummieKames, Inverness District; Figure 57). ForQuaternary networks, this might relate to sitescontaining an extended fossil record,including pollen, insects and molluscs. Thiscan be used to infer vegetation history orenvironmental change

❏ have been studied in detail and which have along history of research and re-interpretation;

❏ have potential for future study❏ have played a significant part in the

development of the Earth sciences, includingformer reference sites, sites where particularBritish geological phenomena were firstrecognised, and sites which were the focus ofstudies that led to the development of newtheories or concepts.

Application of these criteria ensures that siteschosen for a particular network in the GeologicalConservation Review have the greatest collectivescientific value and can be conserved.

Site selection criteria

75

FFiigguurree 5577.. Kildrummie Kamesesker system, Inverness District,viewed towards the east. Twoareas of braided ridges (rightforeground and centre distance)are linked by a single ridge.These striking features wereproduced by glacial meltwaterrivers at the end of the last iceage. Photo: CambridgeUniversity Collection.Reproduced by permission of theCurator of Aerial Photography.

Practical Geological Conservation Review selection methods

76

FFiigguurree 5588.. Ten sites wereselected for the fossil reptilesCretaceous network inBritain to illustrate therange and diversity ofreptiles of this period. Some150 sites were consideredas potential sites for thisnetwork. The sites notincluded as SSSIs may beconserved by other means,such as RIGS or localnature reserves.

Minimum number and minimum areaof sites

In order to ensure that Geological ConservationReview site status is confined to sites ofnational importance, the number of sites

selected is restricted to a reasonable minimum.Only those that are necessary to characterise thenetwork in question, that is to demonstrate thecurrent understanding of the range of Earthscience features in Britain for the network, areselected. These factors are important in thejustification of the scientific value of a GeologicalConservation Review site if it is to be subsequentlydesignated a Site of Special Scientific Interest. Forexample, the scientific case for conserving a givensite is stronger if it is the only one of its kind, or ifit is demonstrably the best of a set of similarexamples (Figure 58).

The area of a Geological Conservation Reviewsite is always kept to a minimum. For example, intracing the form of a major structure over adistance of several kilometres, a small number ofdispersed, representative ‘sample’ sites might be

selected — the minimum number and sizerequired to describe and interpret the featureadequately. There are, however, exceptions to thisgeneral rule: for example, large sites will berequired to represent the range of large-scaleglacial landforms in the uplands of Wales orScotland. In contrast, mine spoil heaps, typically oflimited size, normally form relatively small sites.

METHODS AND WORKING PRACTICE

Site selection procedures within theGeological Conservation Review

The process of site assessment and selectionfor the Geological Conservation Review wasled by Nature Conservancy Council staff

supported by several hundred Earth scientistscontracted to assess sites within their particulararea of expertise.

The starting point for this process was to devisea comprehensive classification of blocks (seeFigure 56) to subdivide the geology andgeomorphology of Britain into a series of subject

Methods and working practice

77

areas. Work on particular blocks typically followedfour stages.

Stage 1: Building and briefing theblock team

For the larger blocks, a co-ordinator (aspecialist member of the Nature ConservancyCouncil or an external expert Earth scientist)

was appointed to oversee the task of assessing andselecting the sites. The co-ordinator’s role was toadvise on site selection criteria and collate thework of a number of contributors who dealt withnetworks of sites within the block. For the smallerblocks, a single Geological Conservation Reviewcontributor often undertook the work, inconsultation with other experts within the field.

Stage 2: Literature review and siteshortlisting

The block co-ordinator or contributor thenundertook an extensive literature search ofboth published and unpublished sources to

create a list of all known Earth science sites ofpotentially national or international importance,relevant to the subject of the block. Whereappropriate, early historical references to specificsites were researched so that potential sites fromthe earliest days of British Earth science could beconsidered for inclusion in the review.

Each of the sites on the draft list was givenstandard basic documentation (e.g. site location,brief summary of scientific interest, possiblejustification for inclusion within a network).

Draft lists were circulated among theappropriate experts for critical assessment andcomment. Sites with significant research potentialwere considered. Following this peer review, ashortlist of candidate sites was drawn up. In thecase of the Jurassic–Cretaceous Reptilia Block, 380potential Geological Conservation Review siteswere identified from the literature as potentiallyspecial; this number was reduced to about 150after first-stage sifting.

Stage 3: Field visits and detailed siteinvestigation

Shortlisted sites were usually visited by theblock co-ordinator or relevant expert to assessand validate the scientific interest.

Following the initial field visits, the list ofpotential sites was refined further by the co-ordinator, in liaison with the specialist advisers forthe block. At this stage, sites where significantdeterioration of the features of interest had takenplace were usually dropped from the list. In somecases it proved necessary to clear exposures ofvegetation and soil, or to sample them remotely, forexample by augering, before an assessment ofpotential could be made. This was particularlytrue of some historically important Quaternarylocalities.

Stage 4: Final assessment andpreparation of Geological ConservationReview site documents

The draft list of potential sites was then reviewedand the sites were once again scrutinised againstthe selection and operational criteria. A final list ofsites meriting inclusion within the particularGeological Conservation Review block was thenprepared. From the list of 150 shortlisted potentialJurassic–Cretaceous Reptilia sites, a final list of 28actual Geological Conservation Review sites wasproduced.

For each proposed Geological ConservationReview site the following documents wereprepared:

❏ a site boundary enclosing the importantfeatures of the site, drawn on 1:10,000Ordnance Survey maps

❏ a concise statement of the scientific interest,typically between 100 and 200 words inlength, an example of which is given in Figure59

❏ a longer statement describing the scientificimportance of the site and citing keyreferences from the literature.

The statement and map form the basis of a key partof the documentation required to notify theGeological Conservation Review sites ascomponents of the SSSI system under the Wildlifeand Countryside Act 1981. The process of workstages applied in selecting sites for a GeologicalConservation Review block is shown schematicallyin Figure 60. SSSIs may contain more than oneGeological Conservation Review site; an exampleis Durlston Bay, South Dorset, SSSI which containssix Geological Conservation Review sites (seeinformation box on page 79).


78

FFiigguurree 6600.. Flow diagram showing a typical site selection process within a GCR block.

Consideration of eachGCR site as an SSSI,qualifying on one ormore counts

Finalshortlisting

Field study

Advice

Guidance on criteria from blockco-ordinator

Advice

DevelopnetworksResearchliterature

FINALISEDGCR SITE

LIST

FINALISEDGCR SITE

LIST(different

block)

REFINEDSITE LIST

SELECTEDGCR BLOCK

Statutory AgencyCouncil or MainBoard Approval

EARTHHERITAGE

SSSI

GCR CONTRIBUTORS

POTENTIAL SITELIST➣

➣

➣ ➣

➣

➣

➣

➣➣

➣

➣➣

➣

➣

GCR BLOCK Quaternary of Wales

NAME OF SITE Dinas Dinlle

COUNTY/DISTRICT Gwynedd

GRID REFERENCE SH 437562

G C R I N T E R E S T

Dinas Dinlle is an important coastal exposure for interpreting latePleistocene glaciation in North Wales. The sequence comprises a complex

series of Irish Sea and Welsh tills with associated sands, silts and gravels.It is complicated by well-developed glaciotectonic structures includingfolds, faults and overthrows, and by cryoturbation features which occur inthe uppermost horizons. The sections have been regarded as showing thenorthernmost occurrence of Irish Sea till belonging to the oldest-knownglacial episode in the area (the Trevor Advance), while the glaciotectonicstructures have been interpreted as evidence for a later readvance of ice.However, recent research suggests that the sediments and glaciotectonicstructures need not be the product of different glacial advances, but can beadequately explained as a multiple drift sequence formed during oneglaciation. The drift sequence, and particularly the glaciotectonicstructures, make Dinas Dinlle a site of significant interest forreconstructing late Pleistocene processes and events in North Wales.

FFiigguurree 5599.. Specimen citation.

GCR sites within Sites of Special Scientific Interest

79

Geological Conservation Reviewsites within Sites of SpecialScientific Interest

The 3002 Geological ConservationReview sites identified will beconsidered for notification as

approximately 2300 SSSIs. The differencein numbers reflects the fact that GeologicalConservation Review sites chosen as partsof different blocks may partly or entirelyoverlap geographically. A single SSSI mayencompass several Geological ConservationReview sites, as well as one or more featuresof special biological value. The diagrambelow shows GCR site overlaps within asingle hypothetical SSSI.

Durlston Bay SSSI, South Dorset, is a goodexample of a large composite site whichincorporates separate and overlappingGeological Conservation Review sites.

Special features of interest found at DurlstonBay have led to the sites’ inclusion in sixGeological Conservation Review blocks, asfollows:

❏ Portlandian–Berriasian Stratigraphy

❏ Mesozoic Mammalia

❏ Palaeoentomology

❏ Mesozoic–Tertiary Fish/Amphibia

❏ Jurassic–Cretaceous Reptilia

❏ Coastal Geomorphology of England.

Each of the six Geological ConservationReview sites within the single Durlston BaySSSI was assessed independently forinclusion within its respective network, andjudged worthy of Geological ConservationReview status in its own right.

Photo: J.G. Larwood.


80

FFiigguurree 6611.. Florence Mine, Cumbria. Mineralogy of the Lake District Block. The importance of this site lies inits excellent exposures within the Beckerment iron ore body, the largest remaining of the iron ore ‘flats’ (an orebody that has replaced a sediment layer) of the West Cumbria mining province, and its contribution to researchinto ore mineralistaion in Britain. At the mine, the variety and form of the ore is displayed in situ. This site isone of seven chosen to represent the variety of iron ore deposits across Britain. It is the only one which showsiron ore replacement flats, a type of deposit unrecorded outside Britain. This site was recently added to theGeological Conservation Review.

At the time of selection of Lake District mineralogy sites, no good in situ exposures were available at thesurface, and a nearby mine dump site was the only available source of material for studying these uniquedeposits. Florence Mine now supersedes the mine dump site. The photograph shows the mine-roof of kidney ore.This part of the mine is to be conserved with the intention of using it as an educational/visitor resource,consequently no removal of in situ specimens is permitted by the mine management. Photo: T. Moat.

The study of the Earth — continuing developments

The final concept to be considered is ‘currentunderstanding’. It is unlikely that the entiregeological and geomorphological record will

ever be fully understood. Given the speed ofscientific change within geology, there is acontinual need to re-survey to ensure that theGeological Conservation Review networks andsites reflect the current state of knowledge. The

Geological Conservation Review is, therefore, anongoing process of refinement and update toensure that conservation keeps pace with currentunderstanding.

The physical character of sites is constantlybeing changed by weathering and vegetationgrowth. Some sites are lost to development, whileother new exposures are created by quarrying andengineering works (Figure 61). Thus a site series isinherently dynamic and should be reviewedperiodically. In practice, such reviews haveresulted in only modest changes since 1990.

Earth heritage conservation

Chapter 6

The need to take active measures to conserveour Earth heritage is, perhaps, less obviousthan for biological sites which we need to

conserve to ensure the survival of endangeredanimals, plants and habitats. Rocks are, after all,hard and durable, and some have existed for manymillions of years. Similarly, some maturelandscapes have remained almost unchanged forcenturies. However, natural resources, such ascrushed rock, sand and gravel, are required to meetthe demands of modern society and carefulplanning is required to ensure that any importantgeological feature is not destroyed in this process.

Threats to the Earth heritage

In modern society, there is an increasing needfor waste disposal sites. Quarries, gravel pits,old mines and caves have all been used to

fulfil this need and some historically importantsites have been lost to science as a result.

Some engineering methods can also poseproblems for Earth heritage sites. In protectingcoastal cliffs from further erosion, rock exposuresof value to science may be covered by engineeringworks (Figure 62). Such practices can also cut offthe sediment supplies which feed and maintainshingle bars, beaches, saltmarshes and mud flats,causing them to become eroded by the action ofthe sea. Similarly, river engineering works havealtered natural fluvial geo-morphological features,and commercial and industrial developments havedestroyed or covered sites. Even the shape of theland has been changed as features are levelled orexploited to extract materials for the constructionindustry, and the planting of coniferous trees inupland areas has damaged geomorphologicalfeatures and obscured geological exposures.

Threats to the Earth heritage

83

FFiigguurree 6622.. Coastal defences atCorton Cliff, Suffolk. This site isimportant as the type section forthe Anglian Stage (part of theQuaternary Period), duringwhich the most extensiveglaciation of Britain occurred.((aa)) The coastal section as itappeared in 1964, beforemodern sea defence works wereundertaken. To the right lies theold sea wall, built in the latenineteenth century to protect aprivate estate. The wallremained intact until the turn ofthe twentieth century, indicatingthe extent of cliff erosion over 60years. ((bb)) The stabilised and vegetatedcliffs at Corton. There are twotypes of structure forming thedefence of the cliffs at thislocality: a steel and concrete walland a timber wave screen.Coastal protection works such asthese may be in conflict withgeological conservation, becausefor some sites continued erosionis necessary to renew exposuresof rock. There is little geologicalinterest in the vegetated slopewithout resorting to excavationwork. Photos: Landform Slides,Lowestoft.

However, development and the effectiveconservation of the Earth heritage are not mutuallyexclusive if properly co-ordinated.

Quarrying and Earth heritageconservation: threats and benefits

Rock exposures created by quarrying andrelated activities have played a key role inthe interpretation of Britain’s geology and

have proved vital to the development of the Earthsciences over the last 200 years. Although activequarrying and conservation of the Earth heritagemay not appear to be compatible, becausequarrying is essentially a destructive process, suchextraction has also revealed more exposures ofrock formations, mineral veins and fossil taxa thanwould otherwise have been known from naturalexposures alone. Therefore, quarrying, and indeedroad construction, can be both a threat and apotential benefit to our knowledge of Earthheritage. Co-operation between the extractionindustry and conservation interests can strike amutually beneficial balance.

Of course, even when a site has been selectedfor Earth heritage conservation, it can still bethreatened by, for example, a change in use ornatural degradation. Conservation is, therefore,not only a matter of site protection and counteringpotential threats, but also of active managementfor the long-term maintenance of the features ofspecial interest.

The remainder of this chapter outlines thehistory of Earth heritage conservation in Britain,explains the current legal framework for theprotection of Earth heritage sites, and considersthe strategy adopted for practical Earth heritagesite conservation.

THE HISTORY OF EARTH HERITAGECONSERVATION IN BRITAIN

Earth heritage conservation in Britain datesback to the mid-nineteenth century. An earlyexample of the concern to conserve

important sites is the action taken to protect FossilGrove in Glasgow, where well-displayed stumpsfrom Carboniferous tree-like plants called lycopodswere enclosed in 1887. They are still protected byGlasgow City Council (Figure 63).

In 1912 the Society for the Protection ofNature Reserves was formed, and graduallythere emerged a more systematic approach

for identifying sites that meritedconservation. In 1941 the Society conveneda conference to consider the place ofconservation in post-war Britain. Theoutcome was the establishment of the NatureReserves Investigation Committee in 1943.This committee identified no fewer than 390geological sites in England and Wales. Afurther 60 geological sites were identified ina subsequent report on Scotland.

This early work prompted the Government tocreate the Wildlife Conservation Special Committee(England and Wales) to examine ways in which theGovernment could further support the nationalnature protection effort. Their report, Conservationof Nature in England and Wales (Cmd 7122, 1947),laid the foundation for nature conservation. Itrecognised a twin approach to nature conservationin which scientific activity developed in parallel


84

FFiigguurree 6633.. Fossil Grove, Glasgow. Stumps of a onceflourishing forest of lycopods. This tree-like plant grewin a tropical forest which covered this area of southernScotland during the Carboniferous Period. The trunks,characterised by diamond-shaped leaf scars, grew upto 30 metres before they branched. Photo: A. Gunning.

with aesthetic and recreational concerns.In 1949 the Nature Conservancy was created by

Royal Charter. The Charter empowered the NatureConservancy to establish National Nature Reservesfor the purposes of nature conservation, includinggeological and ‘physiographical’ (geomorphological)conservation.

In the same year, Parliament passed theNational Parks and Access to the Countryside Act1949 — a milestone in the development ofconservation legislation. The Act led to thecreation of the National Parks in England andWales, conferred powers on local authorities tocreate local nature reserves and required theNature Conservancy to notify local authorities ofthe location of Sites of Special Scientific Interest(SSSIs) by reason of their flora, fauna or geologicalor physiographical features. The prominence ofEarth heritage considerations in the thinking of theCommittee, and subsequently the Act, owes muchto the foresight of Sir Julian Huxley and othermembers of the Committee. While the Act gave nodirect protection to SSSIs, Town and CountryPlanning legislation provides the means ofprotecting sites from being destroyed bydevelopment.

During the 1950s, ’60s and ’70s, Earth sciencestaff of the Nature Conservancy (1949–1973) andthen the Nature Conservancy Council (1973–1991)contributed to the development of the SSSI andNational Nature Reserve (NNR) series. A significantdevelopment in wildlife conservation was theNature Conservation Review (1977) which,between 1966 and 1970, evaluated areas of nationalbiological importance in Britain. The GeologicalConservation Review commenced in 1977, toprovide a parallel audit of the Earth heritage inGreat Britain.

At the same time, much activity by the NatureConservancy Council was devoted to the local andday-to-day concerns of protecting the sites. Thiswas carried out largely by participating asconsultees in the development control process ofthe Town and Country Planning Acts. Also, duringthis period, voluntary conservation bodies, notablyCounty Naturalists’ Trusts, established some Earthheritage sites as non-statutory reserves, whilefurther sites were acquired by local authorities asCountry Parks or statutory local nature reserves.

The next major step forward was theenactment of the Wildlife and Countryside Act1981, which improved arrangements for theeffective conservation of SSSIs. An additional Earthheritage aspect of the Act, with important

implications for landscape conservation, was theprovision for Orders to protect areas of limestonepavement.

The Environmental Protection Act 1990 andthe Natural Heritage (Scotland) Act 1991subdivided the Nature Conservancy Council intothree country-based organisations — theCountryside Council for Wales, English Nature andScottish Natural Heritage. This re-organisationreflected the desire to bring nature conservationcloser to local people. It also afforded theopportunity for the three organisations to developindependent approaches to the subject. Wherecommon concerns and issues arise, such as insetting common standards of practice, the agenciesoperate through the Joint Nature ConservationCommittee (JNCC). The JNCC also hasresponsibility for research and advice on natureconservation at both United Kingdom andinternational levels.

Outside the SSSI network the protection ofEarth heritage sites is undertaken for the most partby voluntary and locally based groups, often withsupport from national Earth science societies andinstitutions. The work of the Geologists’Association and its regional groups is particularlyimportant, and the Conservation Committee of theGeological Society of London is a forum that bringstogether organisations and groups concerned withEarth sciences and site conservation. Since 1990,voluntary local groups have been established tonotify local authorities of Regionally ImportantGeological and Geomorphological Sites (RIGS;Figure 64). These RIGS groups have grown rapidlyand today exist in all English and Welsh counties.Such groups are also being established in Scotlandand Northern Ireland. The work of RIGS groupsoften involves museums, county wildlife trusts,industry and local authorities, as well as localgeologists.

Although RIGS have no statutory status, theycan be protected in a most effective way throughlocal initiatives. Local authorities respondpositively to protect sites that attract local supportand will often accommodate their protectionwithin Local and Structure Plans.

The need to protect Earth heritage sites otherthan SSSIs reflects a number of factors, particularlythe demand for educational sites arising from anincrease of interest in the Earth sciences. OtherEarth heritage sites, with strong aesthetic ratherthan scientific appeal, are not specifically protectedas SSSIs, but are valuable as a stimulation to raisingpublic awareness and appreciation of geology and

The history of Earth heritage conservation in Britain

85

geomorphology. If such sites are of local, ratherthan national, importance, they may be protectedby RIGS schemes. Many geological sites are also oflocal interest and importance for their flora, fauna,archaeology, mining history or amenity value, andthey too may be protected as RIGS.

The network of RIGS groups helps to ensurethat RIGS are accessible and, where appropriate,protected. The RIGS scheme nationwide is ofgreat importance and complements the GeologicalConservation Review.

EARTH HERITAGE SITE PROTECTION

The legal framework

The Environmental Protection Act 1990, theNatural Heritage (Scotland) Act 1991 andthe National Parks and Access to the

Countryside Act 1949 enable the statutoryconservation bodies and local authorities toestablish and manage, respectively, national andlocal nature reserves for the conservation ofwildlife and Earth heritage features. Land can bebought or leased for the purpose, or contractualagreements can be reached with the owners andtenants of the land to ensure its protection andproper management. The 1949 Act also enablesthese bodies to make bylaws to protect thereserves from any type of damage. As a last resort,the statutory conservation bodies and localauthorities have a power of compulsory purchase.

Over the years a number of Earth heritagenature reserves have been established, such asWren’s Nest National Nature Reserve near Dudley,in the West Midlands, which was secured as anNNR in 1956 (the first in the United Kingdom forgeology; Figure 65). The founding of the reserve isin recognition of the exceptional international


86

FFiigguurree 6644.. Coombs Quarry, Buckinghamshire: a RIGS. A collaborative effort by the Buckinghamshire RIGS groupwith the County Council Countryside Section and local geologists opened up and improved this site. Thisinvolved the clearance of the overgrown face, the creation of a new exposure, the provision of walkways andfencing, and the placing of boards with on-site interpretation. The geological interest of the site was first notedin 1860, during mapping by the Geological Survey. The rocks here, the Blisworth Limestone Formation, date fromthe Middle Jurassic, and are about 160 million years old. The nature of the different rock types and fossils of therock beds are now accessible to study. Photo: L. Davies.

importance of the site as a source of Silurian-agefossils. The site has yielded a great variety of fossilsin a superb state of preservation, the best of whichcan be found in museums throughout the world.

However, the 1949 Act recognised that it wouldbe a long time before all important wildlife andEarth heritage sites could be acquired as naturereserves, if ever, and so it also contained aprovision for the Nature Conservancy (and itssuccessors) to notify local planning authorities ofimportant areas, not yet managed as naturereserves, as SSSIs. Once a local authority is notifiedof an SSSI in its area, it is able to protect the sitefrom adverse development under the controlsprovided by the Town and Country Planning Acts.

Individual planning decisions are guided by theStructure, Unitary and Local Plans relating to thearea under consideration. Of particular relevanceare mineral and waste disposal Local Plans.

As well as enabling applications detrimental toconservation interests to be turned down, thePlanning Acts permit conditional consent to begranted. Such consents allow development toproceed on or near an SSSI with adequatesafeguards to avoid damage to the importantwildlife or Earth heritage features of the site.

Planning legislation (Town and CountryPlanning Act 1990 and the Town and CountryPlanning (Scotland) Act 1990) also enables localauthorities to enter into agreements withdevelopers about how their land should bemanaged when development has taken place.These agreements are often negotiated in parallelwith the consideration of planning consent. Anagreement could, for example, require thedeveloper and any subsequent owner to provideaccess to a geological exposure for educational orresearch purposes. If access had been restrictedpreviously, such an agreement could be verybeneficial.

The Planning Acts, and their associated GeneralDevelopment Orders, require local authorities toconsult with the statutory nature conservationbodies before consenting to a developmentproposal affecting an SSSI. Various other statutesplace a similar requirement on a range of statutorybodies and public utilities, including the watercompanies and the National Rivers Authority.

In addition, the Wildlife and Countryside Actstrengthened the protection afforded to SSSIsconsiderably. This Act requires the statutorynature conservation bodies to inform all theowners and occupiers of an SSSI about the natureof the features of special interest of the site and of

the types of activity that could cause damage tothose special features. Before carrying out any ofthese activities, an owner or occupier must givethe appropriate statutory nature conservationagency at least four months’ notice. This enablesthe conservation agency to advise the owner oroccupier how, if possible, the operation might becarried out without damaging the special interest.If that is not possible, a contractual agreement toprotect the site may be negotiated. The financialprovisions of such an agreement are calculated inaccordance with national guidelines.

If an owner or occupier is determined to carryout a damaging activity, and this activity does notrequire planning consent, the Secretary of State

The legal framework

87

FFiigguurree 6655.. The ripple beds at Wren’s Nest NationalNature Reserve in Dudley, West Midlands, viewed fromthe purpose-built observation platform. This visuallyimpressive rock surface provides evidence for theenvironments of the Silurian Period. Similar ripplemarks can be seen today on sandy beaches and riverestuaries. Scree, at the base of the slope, continues toyield a wealth of fossils, including trilobites, for whichWren’s Nest is particularly renowned. Photo: J.Larwood.

may be asked to make a Nature ConservationOrder which extends the period of notice. Such anOrder also has the effect of making it an offence fora member of the public to damage the site.

The 1981 Act also contains a provision enablinga local authority to make a Limestone PavementOrder, on either landscape or nature conservationgrounds, to prevent the removal of rock fromlimestone pavement areas.

Present legislation is proving to be legallyeffective. It is equally important, however, that allconcerned work closely with owners andoccupiers of important sites to promote effectiveconservation management.

EARTH HERITAGE CONSERVATION INPRACTICE

Conservation strategy

Once an Earth heritage site has beenidentified as worthy of special protectionmeasures, a practical conservation

management strategy needs to be developed andimplemented. This strategy involves elements suchas documenting the importance of the site,planning and implementing practical conservationand protection measures, site monitoring and siteenhancement. Although developing sitemanagement strategies was not part of theGeological Conservation Review, such strategiesare a necessary extension of it.

Classification of site types

There are two main types of site:

❏ Integrity sites contain finite deposits orlandforms which are irreplaceable if destroyed. Atypical situation is a glacial landform of limited lateral


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FFiigguurree 6666.. HunstantonCliffs and Morfa Harlech.((aa)) Cliffs at Hunstanton,Norfolk, exposing normalwhite Chalk overlying RedChalk and dark-colouredsandstones. Debris alongthe foot of the cliff indicateserosion, which ensures thatthe rocks in the cliff arealways well exposed.Because there is no chanceof erosion completelyremoving the rocksequence (as it extends wayback beyond the cliffs). It isclassed as an exposure site.Photo: C. D. Prosser.

((bb)) Coastal sand dunes at Morfa Harlech, Gwynedd.These landforms would be destroyed by erosion orcommercial extraction of sand. Therefore they needconserving, by allowing them to evolve naturally, andso they are an example of an integrity site. Photo: S.Campbell.

extent, such as a kame terrace or esker (see Figure35). Other examples include presently active, andpreviously active, geomorphological sites (e.g. MorfaHarlech, Figure 66b), caves and karst, uniquemineral, fossil or geological feature sites, and somestratotypes.❏ Exposure sites provide exposures of a rockwhich is extensive or also well developed below theground surface. Exposure sites are numerically themore common type and may include exposures indisused and active quarries, cuttings and pits;exposures in coastal and river cliffs (e.g. Hunstantoncliffs, Figure 66a); foreshore exposures; mines andtunnels; inland outcrops and stream sections.The broad conservation principles for these typesof site are different. ‘Integrity’ sites are, bydefinition, finite and irreplaceable. To conservethem a more ‘protectionist’ approach must beadopted. In contrast, the broad conservationprinciple for exposure sites depends on themaintenance of an exposure, the precise locationof which is not always critical. Quarrying may bewelcomed under some circumstances because itcreates a fresh exposure and progressively revealsnew rock surfaces, enabling a rock body to beanalysed in three dimensions. Similarly, marineerosion is often vital in the creation of fresh rockfaces at coastal sites, particularly in softer rockformations.

Conservation management of a geo-morphological site depends on whether it is arelict landform or an active process site. Broadly,the requirements for the former will be similar tothose for ‘integrity’ geological sites. Themanagement of dynamic environments is,however, more complex, and requires anunderstanding of geomorphological sensitivity andthe capacity of the system to absorb externallyimposed stresses.

The consideration of the nature of the site as an‘integrity’ or ‘exposure’ site helps a fundamentalconservation principle to be developed: whether toprotect the resource or maintain the exposure.Further general conservation principles can beadded by considering the actual type of the site itself— whether it is an active quarry or coastalexposure, for example, where the likely threats,opportunities and problems are different. Finally,site conservation principles will need to take intoaccount the precise location of the feature of specialinterest within the site. If a feature of interest lies ata cliff base in a quarry, conservation measuresshould ensure that the foot of the cliff is notobscured, but if the only feature is half-way up the

rock face of the quarry, access to it may actually beimproved if sand, shingle or other materials were tobe placed at the foot of the rock face.

Using this framework of integrity/exposure site,site type, and the location of the particular feature(s)within a site, it is possible to draw up generalconservation principles for different types of site,and provide guidance to conservationists as to thelikely threats that may affect them. Building on this,a detailed series of guidelines, the Handbook ofEarth Science Conservation Techniques (1990),produced by the NCC (now available from theCountryside Council for Wales, English Nature andScottish Natural Heritage), describes conservationguidelines for more than 50 site scenarios. However,in order to draw up site-specific conservation planswhich detail the measures essential to maintainingand conserving the interest of a site, and to identifythe measures that would enhance it, detailedassessments need to be made at the site itself.

Practical conservation planning andimplementation will involve the followingelements:

1. Documenting the special interest of a siteThis may be done by reference to scientificliterature, by discussion with experts and bydirect observation at the site. For theGeological Conservation Review sites, theReview itself provides the firm foundation forthe scientific credentials of a site, and sitereports are ultimately documented inGeological Conservation Review volumes.Other documentation schemes are also inoperation, such as the National Scheme forGeological Site Documentation, brieflydescribed in Record of the Rocks, that RIGSgroups use for documenting RIGS sites, andprovides a record of the geology at sites whichcan be used for teaching purposes.

2. Preparing a site conservation planInformation is required about what activitiesand processes would impair the interest at thesite, how it would deteriorate naturallywithout intervention, and what action wouldbe desirable, or even essential, to maintain thefeature(s) of interest. The general scheme ofconservation principles (integrity/exposure,type of site and location of the feature(s) at thesite) can provide broad guidance. This willlead naturally to a consideration of what site-specific and practical Earth heritageconservation measures will be needed to

Classification of site types

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ensure that the features of special interest arenot obscured, destroyed or damaged, and alsoto indicate the recommended frequency ofmonitoring. The country conservationagencies are developing such plans for allGeological Conservation Review sites.

3. Safeguarding the siteSite management involves:

❏ periodic monitoring of the condition of asite so as to anticipate and identify thenature of degradation or damage

❏ carrying out essential site safeguardmeasures, and desirable site enhancementoperations, in response to the above, forexample, site clearance or re-excavationshould a feature become obscured.

In the examples below, potential threats at actualsites are described, and practical solutions to someof the problems that sites may face are indicated.

EARTH HERITAGE CONSERVATIONIN PRACTICE — SOME EXAMPLES

Fossil and mineral collecting andconservation

The collecting of fossils and minerals is generallyregarded as a benign activity which is anintegral part of fieldwork. Many specimens are

more valuable to science when removed from therock than they are in situ, provided that they arecollected in a responsible manner (see below),properly housed, curated and made available for usein a suitable museum. An example is an ‘exposuresite’ such as a cliff face subject to erosion, where newfossils will be exposed continually as the cliff lineretreats. In this case, the overall fossil resource can bevery large, and it is important to collect and recordthe fossils before they are lost to the sea.

However, some rare fossil or mineral reserves arehighly localised and only have a limited supply, suchas an accumulation of fossil bones in a cave. At such‘integrity sites’, irresponsible collecting can be verydamaging. The conservation of such rare andirreplaceable sites in Britain is becoming increasinglyimportant because they represent a finite, non-renewable resource. In many of these cases,conservation of the site will require that collecting iscarefully managed to ensure that the maximumamount of information is gained and the site remainsavailable for appropriate use in the future.

Palaeontological and mineralogical sites differfrom many other Earth heritage sites in theirmanagement requirements, although they suffer thesame potential threats as quarries, cliffs, mines orother outcrops. These threats may involve removal ofthe resource, or it being obscured by infill,afforestation, slope stabilisation or various types ofconstruction. There is also the need to ensure thatpotentially irreplaceable material collected forresearch is properly stored and conserved.

The following guidelines constitute good practice.

❏ Obtain permission before collecting on privateland, and respect the owner’s wishes.

❏ Wear appropriate clothing and footwear. Ahelmet is essential if collecting near cliffs orquarry faces, and protective goggles if a chiselor hammer is used. Avoid collecting indangerous situations. If collecting at the coast,consider tide times prior to the visit. Leavedetails of the collecting site, and your expectedtime of return, with a responsible person.

❏ Take only a few representative specimens, and ifpossible collect only from fallen blocks or loosestones — indiscriminate collecting willdiminish the resource for future visitors.

❏ If removing a specimen from a rock face, makea careful note of its exact position in relation tosurrounding rock; a photograph provides auseful reference. Label the specimen, givingdetails of where and when it was collected.

❏ If possible, remove a fossil complete with someof the surrounding rock, and protect it in paperor cloth for safe transport.

❏ Large fossils can be a problem for the individualcollectors and could be left for others to see;otherwise seek advice from a local museum.Special equipment and lots of time may berequired to excavate large specimens properly.

❏ Mineral collecting from old mines poses specialproblems — such as effects of stability of theold working or gas build up. Old workingsshould only be entered with an organised groupand experienced leaders. Mine dumps can bevisited with permission, however.

A leaflet published by the Geologists’ Associationis available about general conduct and safety onfieldwork.

The activities of collectors, includingcommercially oriented collectors, can unearthspecimens which may otherwise not have come tolight. Collectors should be encouraged to work

with specialists and museum curators so that everypossible opportunity is taken to systematise theircollecting and guarantee that material goes into asuitable repository. Irresponsible collecting maydestroy an entire site, but is very difficult tocontrol.

Coastal sites

Conservation of the Barton GeologicalConservation Review site

The cliffs around Barton-on-Sea in Hampshire (seeFigure 9) have been renowned for their Tertiaryfossils for many years, and are still visited by manypeople each year. The site gives its name to adivision of the Palaeogene sub-Period, theBartonian Stage. The site is also nationallyimportant for its Pleistocene Solent River TerraceGravels.

Fossils are still abundant and are revealed bymarine erosion. However, because of this erosion,the site has been under threat from coastalprotection schemes on numerous occasions in thepast. Previously proposed schemes of rockarmouring, slope protection and slope grading,and the cutting of drains into the section, havealready damaged parts of the site. Nevertheless,sections of natural cliff do remain, immediatelyeast and west of the Barton frontage, althoughthese could be obscured by the expansion ofexisting protection schemes.

Such exposure sites, susceptible to cliff fall, areoften in conflict with engineering schemes seekingto prevent further erosion. Indeed, there is often

intense local pressure to find engineering solutionsto the problem of coastal recession. Coastalschemes commonly involve protective armouring(e.g. concrete sea-walls or rock revetments), whichis often accompanied by cliff grading as well asdrainage pipes and channels. In the extreme, suchschemes can lead to the complete obliteration ofthe geological interest of the site. Alternativemethods of coastal protection, achieving theobjectives of reducing the level of marine erosionwhile limiting the impact of erosion on coastalcliffs of geological importance, have beeninvestigated as part of an ‘engineering forconservation’ initiative.

In the Hampshire example it will only bethrough close co-operation between EnglishNature and the local authority that a mutuallyagreed action plan can be developed, which willafford protection to this world-famous andinternationally important site, while at the sametime addressing the problems of coastal erosion oflocal concern.

Active quarries

Conservation at Shap Granite Quarry

Shap Granite Quarry is a working quarry (Figure67). The danger of falling blocks from unstablefaces is brought about largely by the distinctive

jointing pattern of the granite, whereby three sets ofjoints intersect to produce rectangular blocks,many of which are cut and used for decorativebuilding stone. The rest of the granite is crushedand used for aggregates and pipe manufacture.

Active quarries

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FFiigguurree 6677.. The ShapGranite Quarry, Cumbria,showing regular jointingand the unstable face.This is an example of anexposure site. Photo: J. L.Eyers.

The quarrying company allows a limitednumber of parties to visit the quarry each year andthese are usually directed to an area of prepareddisplay blocks (Figure 68). The quarry face can beseen easily from the display area, but close accessis not permitted. The blocks have been carefullyselected to show all the features of the granite andits mineralisation and guarantee a selection of thecharacteristic ‘pink’ and ‘dark’ varieties of ShapGranite, unusually zoned minerals, a variety ofveins and surface mineralisation. Weatheredblocks, illustrating granite decomposition, as wellas some specimens from the nearby Blue Quarry,are also on display.

The blocks provide an excellent selection ofrocks and minerals which may otherwise not beavailable on any one visit to the quarry, becauseworking quarries can uncover and then loseinteresting features very rapidly. Thus the displayrepresents an excellent way of maintaining thegeological and educational interest of the site, whileensuring safety to the public.

Alternatively, agreements can be made with aquarry owner that one exposure face should beavailable for study as rock extraction progresses, andthat a final face should be left intact when quarryingceases. The precise location of the exposure is notcritical in cases where the special interest lies in therock type which is present throughout a quarry. By‘smooth blasting’ the face, rather than productionblasting (which is used for normal extraction andtends to leave remaining rock faces shattered), it is

possible to create a stable and safe exposure of therock for study. When extraction in the quarry is tocease, it is expected that a ‘final’ exposure will beagreed with the quarry owner and that this would bemaintained as a permanent location of interest. Thiswould be subject to the disused quarryconsiderations outlined below.

Disused quarries

Conservation at Ercall Quarry,Shropshire

The large area of hillside outcrop at Ercall isfairly safe from many of the common threatssuch as dumping, building construction and

afforestation. The site includes a disused quarry(Figure 69), an exposure site. As a result of thecessation of quarrying activity, operations thatwere considered to constitute ‘normal workingpractice’ for mineral extraction are nowconsidered damaging to the SSSI. For instance,activities such as the construction or removal ofroads, tracks, walls or ditches, the laying orremoval of cables or pipelines above or belowground, and the building of temporary orpermanent structures were not considered a threatto the site during the period of active working.However, after active mineral extraction hasfinished, these operations are possible threats tothe remaining exposure.


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FFiigguurree 6688.. Close up of a displayblock in the ‘safe’ area of ShapGranite Quarry. One of themain features of the granite isthe large crystals of pink feldspar.These may have either developedat an early stage during magmacooling and solidification, orgrown later in the solidifiedgranite, during metamorphism.The nature of the darkfragments in the granite is alsodebated. Some believe that theseare actually fragments of adarker magma which waspresent at great depth, and wasintermixed with the palergranite by convection processes,engulfing some of the pinkcrystals en route. Others believe that the dark fragments were part of the surrounding rock which became engulfed andthe pink crystals grew within them during metamorphism. Photo: J. L. Eyers.

General considerations at disused quarries

At Kirtlington, Oxfordshire (Figure 70), theremoval of slumped material that mayobscure the lower rock layers may be

desirable. Some of the material may, however, bea useful platform for access to higher sections, andit may also provide a resource for samplecollecting. In softer sediments, where rock debrismay accumulate at the quarry cliff foot, thus

obscuring substantial parts of the exposure, it maybe advantageous to create a ‘stepped’ face (seeFigure 71).

Should a face like this become vegetated, it maybe necessary to clean it every few years, althoughother conservation interests will need to bebalanced. For example, a vegetated face maybecome a valuable nature conservation resourcefor other reasons, such as butterflies in abandonedchalk quarries.

Disused quarries

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FFiigguurree 6699.. The disused Ercall Quarry in Shropshire displays the Vendian (end ‘Precambrian’) – Cambrianboundary. The steeply dipping beds are of Cambrian age. These beds contrast distinctly with the pale, non-beddedform of the Precambrian quartzite on the far left of the photograph. Photo: C. D. Prosser.

FFiigguurree 7700.. The rockexposure at the disusedKirtlington Quarry inOxfordshire is importantfor Middle Jurassic fishfossils. Photo: J. G.Larwood.


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Other considerations at sites similar to this couldinclude diverting water run-off away from the rockface of interest, or adding a drainage system nearbyto prevent flooding at the base of the face whichwould impede access. Such exposures may alsoneed to be stabilised, by removing loose rock from aselected area (perhaps by pneumatic breaker orsmooth blasting) or by adding supportive mesh orrock bolts to higher sections (if impairing access isnot a problem). Any remaining dangerous areascould then be fenced off.

There may also be problems related to flytipping in disused quarries, and vehicular access tothe quarry edge may need to be impeded, perhapsby placing boulders to make a barrier.

Disused quarries as landfill sites

The main threat at the end of the working lifeof any quarry is subsequent use as a landfillsite. However, despite the impacts of

landfill, a sympathetically designed schemeincorporating geological exposures can provide anopportunity for the long-term conservation ofimportant faces. M. J. Carter Associates providedan assessment report for the Nature ConservancyCouncil on the stability of refuse slopes. From thiswork a number of options have been identified forconservation within landfill sites (Figure 71). Forexample:

❏ contouring the landfill material aroundgeological faces

❏ creating reinforced earth walls around ageological face

❏ making alternative exposures by digging aface outside the proposed landfill site.

Stability, drainage, leachate and landfill gas are themain considerations and cost will play a large partin the choice of the preferred option.

FFiigguurree 7711.. ((aa)) Diagram of a ‘stepped’ face in soft sediments which prevents the build up of all of the talus at thecliff foot. Diagrams ((bb)) to ((dd)) show idealised sections of conservation schemes within landfill sites.

Cave conservation

Caves (and associated karst sites) can beregarded as ‘integrity’ sites, because thefeatures of interest are often irreplaceable

(Figure 72). The broad conservation approach istherefore based on protection. The inaccessibility ofsome of these caves protects them to some extent.However, some very good localities have been lost ordamaged because of caving activities, quarrying orcollection by amateurs or professional dealers. Otheractivities can also be highly damaging if unmodified,such as effluent disposal and dumping, and entranceclosure. Damage from changes in agriculturalpractice, water abstraction from boreholes andrecreational caving can usually be avoided if theactivity is sensitively planned and carried out. The use

of specific cave conservation plans is one method ofaddressing the threats to cave sites.

As well as their importance for geology andgeomorphology, caves are also important for theirarchaeology and fauna and flora; for example, theyprovide important hibernacula and breeding sites forseveral species of bat. In developing conservationplans for caves, the requirements of each type ofinterest will need to be balanced.

Issues of safety will be of the utmost importancefor geologists studying cave sites, and the NationalCaving Association (NCA) code of conduct should befollowed in this regard. The NCA has also publisheda National Cave Conservation policy (1995) inassociation with the statutory conservation agencies,and it describes in detail the issues concerning theconservation of caves.

Cave conservation

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FFiigguurree 7722. The spectacular, irreplaceable cave formations of the White River Series, Peak Cavern, Derbyshire.Photo: P. R. Deakin.


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Road construction

Conservation of Claverley Road Cutting

In the process of road construction, geologicalfeatures may be threatened if, for example, acutting is to be made. On the other hand, this

process may also create an exposure where therewas none before. The conservation principles andpractice here will depend on the net effect ofcreation against removal. The Claverley RoadCutting is an example of a man-made inlandexposure site (Figure 73). As a road cutting, the faceneeds periodic monitoring to determine its stability.

The site is not subject to any immediate threats butvegetation may obscure rock faces over a period ofyears.

At some road cutting sites, stabilisation isprovided by rock bolts which help to maintainfriction between adjoining blocks of rock. Drains,which divert water from the top of the section,may also be installed to help stability (as waterrunning between blocks would lead to high waterpressure, and so cause slippage).

The issue of safety for people examining therock faces at road cuttings is important whenconsidering the open access to such sites,particularly on busy roads. Regular monitoring of

FFiigguurree 7733.. ClaverleyRoad Cutting, Shropshire.The site is important forthe study of ancient riverenvironments thatexisted in the TriassicPeriod. Photo: EnglishNature.

FFiigguurree 7744.. Excavation ofdinosaur remains atBrighstone Bay, Isle ofWight. The skeletonseems to be that of asauropod dinosaur whichdied on a land surfacethat was subsequentlyinundated by flooding.The seemingly chaoticdisarticulation anddistribution of the bonescould be explained byscavenging of the carcassprior to flooding. Photo:S. Hutt.

road cutting sites by local authorities ensures thatthey are safe. A number of recent publicationsencouraging good practice and a wider awarenessby site users appear to have been effective inreducing the incidence of damage, such as thatcaused by rock coring.

Site excavation and specimen curation

The excavation in Brighstone Bay, Isle of Wight

After the initial discovery in 1992 of dinosaurbones weathering out from the cliff face atBrighstone in rocks called the Wessex

Formation, funds for excavation were obtainedfrom English Nature and the Curry Fund of theGeologists’ Association. The initial dig lasted abouta month and enlisted much local help (Figure 74).Approximately 30% of a medium-sized dinosaurskeleton was carefully exposed, numbered, plotted,photographed, plastered and transported back tothe museum premises on the Isle of Wight.

Conservation of activegeomorphological process sites

Conservation of the River Dee: a mobile meander belt

The River Dee (Figure 75) is one of only a few,large rivers with a well-developed, mobilemeander belt in its lower course that is

relatively free from direct human intervention. The

pattern and scale of the meanders at this site areexceptional. Tortuous, double-horseshoe meanderbends are sustained over a relatively long distancebetween Holt and Worthenbury. There has also beenconsiderable channel change by meander migration

Conservation of the River Dee

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FFiigguurree 7755.. ((aa)) A river cliff ofthe outermost part of ameander of the River Dee,between Holt andWorthenbury. The shape ofthe meander continues tochange as the cliff is eroded.Photo: S. Campbell. ((bb)) Meanders of the Deeviewed from the air. Photo:National Remote SensingCentre Limited (Air PhotoGroup).

a

b

and cut-off during historical times. This can beclearly seen on old maps of the area which showthe English–Welsh border as it followed the riveralong a completely different course.

This locality includes both active and staticgeomorphological features of scientific importancein its active and abandoned channels(palaeochannels). By studying rivers like the Dee, aclearer picture of erosion and deposition processes,and meander development, can be gained, whichcan be important in understanding how riversmodify the landscape through time.

The main objectives in conserving this site areto maintain the fossil landforms (the valley, variousancient river cliffs, palaeochannels and abandonedmeanders) in as natural a state as possible, and toallow the presently active natural processes oferosion and deposition of sediment to continuewith minimal intervention, thereby allowing thechannel to undergo natural changes which includemeander migration. The boundary of this site istherefore sufficiently large to allow for future riverchannel changes.

Potential threats include river managementworks, such as bank maintenance, the constructionof flood defence structures and floodwatermanagement, which prevents the naturaldevelopment of the floodplain. There is someevidence to suggest that the meander belt is not asactive as it once was, which may be the result ofriver management upstream, particularly theregulation of discharges.

Large-scale river management works, whicheither modify the meanders or completely stabilise

parts of the reach, must, therefore, be viewed ashighly undesirable. In both a morphological sense(the alteration of the shape or form of thelandforms) and a dynamic sense (havingunquantifiable effects downstream in terms oferosion and deposition).

Mine dumps

Writhlington Rock Store SSSI

Writhlington Rock Store was nearly buriedas part of a landscaping scheme, but withthe co-operation of British Coal, and

assistance from the Curry Fund of the Geologists’Association and English Nature, a section of the spoilwas left untouched. The rock contains rare plantand insect fossils from the Carboniferous Period, andthe continued access to the material has encourageda great many important finds to be made byprofessional palaeontologists and amateurcollectors (Figure 76). These finds havesignificantly enhanced our understanding of theevolution and diversity of Carboniferous insects.The area is regularly turned by machinery toexpose new spoil especially for collectors.

Site ‘burial’

The deliberate burial of a site, which containssensitive or unique material susceptible toweathering or over-collection, is another

practical method of Earth heritage conservation.Similarly, it may be desirable to leave a site naturallycovered by soil/vegetation (as is the case at the


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FFiigguurree 7766.. The rock pilesat Writhlington RockStore SSSI are animportant source ofplant and insect fossils.Photo: C. D. Prosser.

Rhynie Chert site, Figure 46). If the site containssediment which is unconsolidated, naturalvegetative cover may help to diminish the effectsof weathering and erosion. In these examples theoccasional excavation of the sites for research maybe desirable.

Publicity and public awareness

Achieving recognition of a site with regard toits importance to conservation is possiblethrough education and site publicity. This is

also part of conservation, as is encouraging the ‘use’of the site for scientific research or education andtraining. This can be done in a number of ways,including erecting information sign boards on site(Figure 77), media publicity and producing booksand leaflets about particular sites or groups of sites.Of course, SSSI status does not automatically implyopen access to private land, however.

Advice on conservation of Earthheritage sites

For Geological Conservation Review sites andSSSIs, local planning authorities, statutorybodies, potential developers and owners and

occupiers should seek the advice of theappropriate local office of the relevant statutorynature conservation body before authorising orcarrying out a potentially harmful activity at thesite, or when planning any improvement to thesite. The various offices of the bodies, and theareas they cover, are given in the Appendix to thisbook.

Further guidance on practical site conservation isgiven in A Handbook of Earth ScienceConservation Techniques (the appendices to EarthScience Conservation in Great Britain — AStrategy).

Advice on conservation of Earth heritage sites

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FFiigguurree 7777.. The signboard at Hunstanton,Norfolk. Photo: C. D.Prosser.

The Geological ConservationReview in the context of the

wider Earth heritageconservation effort

Chapter 7

One of the aims of this volume has been toshow that Great Britain contains a varied,fascinating and scientifically invaluable

Earth heritage, which also contributes a great dealto Britain’s landscape, wildlife, economy andscenic beauty. Our Earth heritage is, therefore, notonly a scientific resource, but also a part of oureconomic, cultural and ecological inheritance.

Countless geologists, professional and amateur,have sharpened their scientific minds by studyingthe rocks and landscapes of Britain. As a result,many conceptual advances in the Earth scienceswere made here. It might be argued that all of thesites which have played a significant part in thedevelopment of the Earth sciences should beconserved. This would be impractical. Thus theconservation of the Earth heritage resource ofGreat Britain has focused on selecting a series ofsites that geologists consider important for theGeological Conservation Review.

For the first time it has been possible to takestock of the geological resource of Britain in acomprehensive way using standard criteria. Thepublished results of the Geological ConservationReview provide not only a thorough science-basedfoundation for practical Earth heritageconservation within the series of notified Sites ofSpecial Scientific Interest, but also acomprehensive account of the geology andgeomorphology of Britain.

Earth heritage conservation strategy

In 1990, the Nature Conservancy Councilpublished Earth Science Conservation inGreat Britain — A Strategy, which provided a

detailed and practical guide to meeting thechallenge of Earth heritage conservation. It gavean overview of the problems that needed to beaddressed, the means by which conservation canbe effected, and the organisations best placed totake an active role. It provided a platform fortaking Earth heritage conservation forward. Sinceits publication, the majority of its themes havebeen carried out successfully and developed, andhave made valuable contributions to theconservation and promotion of our Earth heritage.

The strategy highlighted six areas for action:

❏ maintaining the SSSI series through themechanism of the Geological ConservationReview

❏ expanding the RIGS network❏ developing conservation techniques❏ improving documentation and conservation

of geological samples❏ increasing public awareness❏ developing international links.

Since 1990, there have been changing emphaseson the approaches to Earth heritage conservation.The creation of new conservation agencies, theCountryside Council for Wales, English Nature,Scottish Natural Heritage and the Joint NatureConservation Committee, has provided a newinstitutional framework. Increased publicawareness and participation in local groups, theexpanding RIGS network, the growth of geologicalleisure pursuits, the incorporation of geologicalsites into local authority plans and thedevelopment of new conservation techniques,have all influenced the ways in which Earthheritage conservation is perceived. The latestdevelopments regard the Earth heritage as anintegral part of our natural heritage.

For the continuing success of Earth heritageconservation strategies, it is important that allsectors of the community participate. Thisrequires the involvement of local authorities andother statutory bodies, landowners and sitemanagers, Earth science societies, museums,county wildlife trusts and other local and nationalconservation bodies, the higher education sector,schools and field centres and, of course, thegeneral public. It is hoped that industry, whichrelies upon raw materials, and public utilities,which use the resources of the land and water, willcontinue to support the aims of Earth heritageconservation.

Progress and developments in earthheritage conservation

Maintaining the SSSI series throughthe mechanism of the GeologicalConservation Review

As our understanding of geology andgeomorphology changes with the insightsprovided by new discoveries and advances

in Earth science theory, so new sites may need tobe considered as Earth heritage SSSIs. Moreover, ifa site has deteriorated or been lost, a replacementwill need to be identified and notified in its place.The mechanism of the Geological Conservation

Progress and developments in Earth heritage conservation

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Review and its criteria are still applied when newor replacement sites are being considered. In viewof this, the existing Geological ConservationReview blocks and networks will need to bereviewed and updated from time to time.

In the years since the strategy was published, ithas become clear that future developments instatutory Earth heritage conservation will probablyrequire attention to focus on a number of newareas, such as culturally and historically importantsites, soils, hydrogeology and sea-bed localities.

Expanding the RIGS network

Interest in sites outside the SSSI framework ofstatutory protection is increasing and there isalready a recognised need to mobilise voluntary

bodies to take responsibility for sites of regionalimportance, such as RIGS. Greater participation inlocal groups has extended the RIGS networks, andthis has been accompanied by an increase ingeological leisure pursuits. There are now activeRIGS groups in all the counties in England andWales, and many in Scotland.

Developing conservation techniques

As well as developing and refining Earthheritage conservation practice (see Chapter6), recent developments to find technical

solutions to key problems threatening sites includethe investigation and evaluation of ‘soft’engineering techniques to reduce coastal erosion,as alternatives to ‘hard coastal defences’ that canobscure geological exposures and disrupt thetransport of sediment along coasts. Newengineering and blasting techniques are also beingdeveloped which can provide safe, stableexposures of rocks. Similarly, landfill schemes,which are sympathetic to the need for Earthheritage site conservation, have been furtherrefined, so that the requirements of society arebalanced with the need for conserving rockoutcrops for study.

Quaternary geology can help us to understandthe effects of processes such as climate change andits interaction with ecology. This knowledge canassist us in planning conservation responses in achanging world.

Geomorphologists with their specialistknowledge of active sites have an important role toplay in the development of new conservationapproaches. They can advise on the practical use

and management of natural resources, based on asound understanding of geomorphologicalprinciples, and the physical and chemical changeswhich are taking place as the result of interactionbetween human land use and natural systems.

Improving documentation

Besides Geological Conservation Reviewpublications, a programme of preparing sitemanagement plans (see Chapter 6) for all

Earth science sites is continuing. These aredesigned to assist local staff in the statutory natureconservation agencies to appreciate the Earthheritage significance of sites and to enable them topursue ways of enhancing the scientific andcultural values of sites in the light of any threats.Publications with wider appeal are also beingproduced, which will contribute to a greaterpublic awareness of Britain’s Earth heritage.

Increasing public awareness

There is need for a greater publicunderstanding and awareness ofenvironmental matters. The place of Earth

science conservation in nature conservation needsgreater and continuing exposure, througheducation and joint action.

The increasing circulation of the magazineEarth Heritage (formerly Earth ScienceConservation) indicates an enhanced awareness ofEarth heritage issues. This is a reflection of thepublication of articles with more popular appeal;also, there is a general increase in the place ofEarth heritage issues on the wider conservationscene. The series of publications LandscapeFashioned by Geology, published by ScottishNatural Heritage in association with the BritishGeological Survey, aims to describe Scotland’sgeology in more accessible terms and is a modelfor others to follow.

Since 1990, two national conferences haveconsidered specific problems of conserving ourIce Age heritage (‘Evolving landforms and Ice AgeHeritage’, held in May 1992 in Crewe) and thespecial needs of mineralogical sites (‘ConservingBritain’s Mineralogical Heritage’, held atManchester University in March 1992).

At a site-specific level, a number of informationboards and interpretation panels have now beenerected at sites across Britain to carry messages tothe public; more will follow.

The wider Earth heritage conservation effort

104

Developing international links

Throughout the United Kingdom, and indeedinternationally, there is a growing interest inEarth heritage conservation. As well as the

national conferences mentioned above, there havebeen two international meetings, at Digne, inFrance (1991), and Great Malvern (1993).

A debate on the merits of developinginternational guidelines to address geological andlandscape conservation issues was held at theMalvern Conference and is continuing via aninternational group, the ‘Malvern Task Force’. Acentral issue (which is directly relevant to theGeological Conservation Review) is that ofprotecting and managing internationally importantsites to agreed international standards.

These activities take place in a context ofincreasing environmental awareness and actionfollowing the United Nations Conference onEnvironment and Development (UNCED) at Rio deJaneiro in 1992. They reflect a growing awarenessof the interdependence between the well-being ofthe Earth and its peoples.

Earth heritage and nature conservation

The Rio Conference gave an impetus to effortsto manage natural resources in a sustainableway. As a result, attention is focused on the

management of natural ecosystems to preventenvironmental deterioration.

For example, sediments from catchments andcoastal cliffs are naturally transported into thecoastal zone, and these are essential for themaintenance of sand dunes, beaches, mud flats andsaltmarshes. Linking into the coastal system is thefluvial transport system, where sediment is carriedfrom a river catchment area to the floodplain,estuary and adjacent sea areas. The artificialstabilisation of any part of these dynamic naturalprocesses could drastically interfere with theirbalance and so impoverish the naturalenvironment.

Recent geological history, hydrology, soil typeand soil moisture, topography and aspect allinfluence plant and animal habitats. The herb-richgrassland vegetation characteristic of the manyupland limestone areas is very different from themoorland and bog vegetation which develops onupland acid soils overlying sandstone or granite.Any alteration to the acidity of these soils and theirpatterns of drainage can have fundamental effectson their local ecosystems.

These examples show how important it is tounderstand ‘whole’ systems and the relationshipsbetween processes at work in the Earth and lifesciences. English Nature has developed a conceptbased on the identification in England of NaturalAreas. These are defined largely on the basis oftheir underlying geology, landforms and soils,together with the characteristic natural vegetationtypes and wildlife species they support. Thisconcept will provide a new foundation forestablishing conservation objectives based on the‘whole-environment’ approach to which localpeople can contribute. A parallel series of NaturalAreas, based largely on sediment erosion, transportand deposition systems, has been developed forcoastal regions in England. In Scotland, ScottishNatural Heritage is developing a similar conceptusing geology, landforms and soils to identify aseries of biogeographic zones. The importance ofsoils, somewhat neglected hitherto in natureconservation, is now gaining increasedprominence and their study within the concept ofsustainability is likely to become an important taskfor the future. In Wales, the Countryside Councilfor Wales is also developing a landscape strategy tointegrate geological, geomorphological andbiological conservation, allied to public awarenessand enjoyment.

Today, in the light of international, national andlocal activities dedicated to the conservation of theEarth heritage of Britain, it is now possible to takeeffective steps to safeguard the legacy of the pastfor future generations. The GeologicalConservation Review has made this possible.

Earth heritage and nature conservation

105

Regional and Local Offices

1 North Wales Region

Bangor — North West Area

Bryn Menai, Holyhead Road,Bangor, Gwynedd LL57 2EF(01248) 373100, Fax (01248) 370734

1a Mold — North East Area

Victoria House, Grosvenor Street,Mold, Clwyd CH7 1EJ(01352) 754000, Fax (01352) 752346

1b Bala — North East Area

Midland Bank Chambers, 56 High Street,Bala, Gwynedd LL23 7AB(01678) 521226, Fax (01678) 752346

1c Dolgellau — North West Area

Victoria Buildings, Meurig Street,Dolgellau, Gwynedd LL40 1LR(01341) 423750

Appendix

107

Appendix

COUNTRYSIDE COUNCIL FOR WALES

Headquarters Offices

Plas Penrhos,Ffordd Penrhos,Bangor,GwyneddLL57 2LQ(01248) 370444Fax (01248) 355782

●

●

▲

Headquarters

Regional Offices

Local Offices

2. Dyfed — Mid Wales Region

Aberystwyth — West Area

Plas Gogerddan, Aberystwyth,Dyfed SY23 3EE(01970) 828551, Fax (01970) 828314

2a Newtown — East Area

First Floor, Ladywell House,Park Street, Newtown, Powys SY15 1RD(01686) 626799, Fax (01686) 629556

2b Llandrindod Wells — East Area

3rd Floor, The Gwalia, Ithon Road, Llandrindod Wells, Powys LD1 6AA(01597) 824661, Fax (01597) 825734

2c Llandeilo — West Area

Yr Hen Bost, 56 Rhos Maen Street,Llandeilo, Dyfed SA19 6HA(01558) 822111, Fax (01558) 823467

2d Fishguard — West Area

Sycamore Lodge, Hamilton Street,Fishguard, Dyfed SA65 9HL(01348) 874602, Fax (01348) 873936

2e Martin’s Haven — West Area

Skomer Marine Nature Reserve,Fishermen’s Cottage, Martin’s Haven,Haverfordwest, Dyfed SA62 3BJ(01646) 636736, Fax (01646) 636744

2f Stackpole — West Area

Stackpole Home Farm, Stackpole,Nr Pembroke, Pembrokeshire SA71 5DQ(01646) 661368

3 South Wales Region

Cardiff — South Area

Unit 4, Castleton Court,Fortran Road, St Mellons,Cardiff CF3 0LT(01222) 772400, Fax (01222) 772412

3a Swansea — South Area

RVB House, Llys Felin Newydd,Phoenix Way, Swansea Enterprise Park,Llansamlet, Swansea SA7 9FG(01792) 771949, Fax (01792) 771981

3b Abergavenny — East Area

Unit 13B, Mill Street Industrial Estate,Abergavenny, Gwent NP7 5HE(01873) 857938, Fax (01873) 857938

Appendix

108

Local Area Teams

1 Northumbria Team (Northumberland, Durham, Tyne & Wear and Cleveland)

Archbold House, Archbold Terrace,Newcastle-upon-Tyne NE2 1EG(0191) 281 6316, Fax (0191) 281 6305

2 Cumbria Team

Blackwell, Bowness-on-Windermere,Windermere, Cumbria LA23 3JR(015394) 45286, Fax (015394) 88432

3 North West Team (Lancashire, Merseyside and Greater Manchester)

Pier House, Wallgate,Wigan, Lancashire WN3 4AL(01942) 820342, Fax (01942) 820364

Appendix

109

ENGLISH NATURE

Head Office

Northminster House,Northminster,PeterboroughPE1 1UA

(01733) 340345Fax (01733) 68834

4 North & East Yorkshire Team (includes North Humberside)

Institute for Applied Biology,University of York,York YO1 5DD(01904) 432700, Fax (01904) 432705

4a Leyburn Office (Yorkshire Dales)

Thornborough Hall, Leyburn,North Yorkshire DL8 5AB(01969) 23447, Fax (01969) 24190

5 Humber to Pennines Team (South & West Yorkshire & South Humberside)

Bullring House, Northgate,Wakefield, West Yorkshire WF1 3BJ(01924) 387010, Fax (01924) 201507

6 East Midlands Team (Leicestershire, Lincolnshire & Nottinghamshire)

The Maltings, Wharf Road,Grantham, Lincolnshire NG31 6BH(01476) 68431, Fax (01476) 70927

7 Peak District & Derbyshire Team

Manor Barn, Over Haddon,Bakewell, Derbyshire DE45 1JE(01629) 815095, Fax (01629) 815091

8 West Midlands Team (Cheshire, Shropshire, Staffordshire, Warwickshire & West Midlands)

Attingham Park, Shrewsbury,Shropshire SY4 4TW(01743) 709611, Fax (01743) 709303

8a Banbury Office (Warwickshire)

10/11 Butchers Row, Banbury,Oxfordshire OX16 8JH(01295) 257601

9 Three Counties Team (Gloucestershire & Hereford and Worcester)

Masefield House, Wells Road,Malvern Wells, Worcestershire WR14 4PA(01684) 560616, Fax (01684) 893435

10 Bedfordshire, Cambridgeshire & Northamptonshire Team

Ham Lane House, Ham Lane,Orton Waterville, Peterborough PE2 5UR(01733) 391100, Fax (01733) 394093

11 Norfolk Team

60 Bracondale, Norwich,Norfolk NR1 2BE(01603) 620558, Fax (01603) 762552

12 Suffolk Team

Norman Tower House, 1-2 Crown Street,Bury St Edmunds, Suffolk IP33 1QX(01284) 762218, Fax (01284) 764318

13 Essex, Hertfordshire & London Team

Harbour House, Hythe Quay,Colchester, Essex CO2 8JF(01206) 796666, Fax (01206) 794466

13a London Office

Room 801, Chancery Lane,Chancery House, London WC2A 1QU(0171) 831 6922, Fax (0171) 404 3369

14 Kent Team

The Countryside Management Centre,Coldharbour Farm, WyeAshford, Kent TN25 5DB(01233) 812525, Fax (01233) 812520

15 Sussex & Surrey Team

Howard House, 31 High Street,Lewes, East Sussex BN7 2LU(01273) 476595, Fax (01273) 483063

16 Thames & Chilterns Team (Berkshire, Buckinghamshire & Oxfordshire)

Foxhold House, Crookham Common,Thatcham, Berkshire RG19 8EL(01635) 268881, Fax (01635) 268940

17 Hampshire and Isle of Wight Team

1 Southampton Road, Lyndhurst,Hampshire SO43 7BU(01703) 283944, Fax (01703) 283834

Appendix

110

18 Wiltshire Team

Prince Maurice Court, Hambleton Avenue,Devizes, Wiltshire SN10 2RT(01380) 726344, Fax (01380) 721411

19 Dorset Team

Slepe Farm, Arne,Wareham, Dorset BH20 5BN(01929) 556688, Fax (01929) 554752

20 Somerset & Avon Team

Roughmoor, Bishop’s Hull,Taunton, Somerset TA1 5AA(01823) 283211, Fax (01823) 272978

21 Devon & Cornwall Team

The Old Mill House, 37 North Street,Okehampton, Devon EX20 1AR(01837) 55045, Fax (01837) 55046

21a Cornwall Office

Trelissick, Feock,Truro, Cornwall TR3 6QL(01872) 865261, Fax (01872) 865534

Appendix

111

Appendix

SCOTTISH NATURAL HERITAGE

Headquarters Offices

Secretariat, Resources Directorate,Policy Directorate, CommunicationsDirectorate

12 Hope Terrace, Edinburgh,EH9 2AS(0131) 447 4784Fax (0131) 446 2277

Research and Advisory ServicesDirectorate, Information andLibrary Services

2 Anderson Place,Edinburgh EH6 5NP(0131) 447 4784Fax (0131) 446 2405

112

●

●

▲

Headquarters

Regional Offices

Local Offices

Regional and Local Offices

1 North West Region

Fraser Darling House, 9 Culduthel Road,Inverness IV2 4AG(01463) 239431, Fax (01463) 710713

1a Caithness and Sutherland Area

Main Street, Golspie,Sutherland KW10 6TG(01408) 633602, Fax (01408) 633071

1b Ross & Cromarty and Inverness Area

Fodderty Way, Dingwall Business Park,Dingwall IV15 9XB(01349) 865333, Fax (01349) 865609

1c Lochaber & Skye and Lochalsh Area

Mamore House, The Parade,Fort William, Inverness-shire PH33 6BA(01397) 704716, Fax (01397) 700303

1d Western Isles Area

32 Francis Street, Stornoway,Isle of Lewis HS1 2ND(01851) 705258, Fax (01851) 704900

2 North East Region

Wynne-Edwards House, 17 Rubislaw Terrace,Aberdeen AB1 1XE(01224) 642863, Fax (01224) 643347

2a Northern Isles Area

2-4 Alexandra Building, The Esplanade,Lerwick, Shetland ZE1 0LL(01595) 693345, Fax (01595) 692565

2b Strathspey Area

Achantoul, Aviemore,Inverness-shire PH22 1QD(01479) 810477, Fax (01479) 811363

2c East Grampian Area

48 Queen’s Road, Aberdeen AB1 6YE(01224) 312266, Fax (01224) 311366

3 South East Region

Battleby, Redgorton,Perth PH1 3EW(01738) 444177, Fax (01738) 444180

3a Tayside Area

55 York Place, Perth, PH2 8EH(01738) 639746, Fax (01738) 442060

3b Central and Fife Area

The Beta Centre, Innovation Park,University of Stirling, Stirling FK9 4NF(01786) 450362, Fax (01786) 451974

3c Lothian and Borders Area

Anderson’s Chambers, Market Street,Galashiels TD1 3AF(01896) 756652, Fax (01896) 750427

4 South West Region

Caspian House, Mariner Court,Clydebank Business Park, Clydebank G81 2NR(0141) 9514488, Fax (0141) 9514510

4a Argyll and Bute Area

1 Kilmory Industrial Estate, Kilmory, Lochgilphead, Argyll PA31 8RR(01546) 603611, Fax (01546) 602298

4b Mid and South Strathclyde Area

Caspian House, Mariner Court,Clydebank Business Park, ClydebankG81 2NR(0141) 951 4488, Fax (0141) 951 8948

4c Dumfries and Galloway Area

Carmont House, Crichton Royal Estate,Bankend Road,Dumfries DG1 4UQ(01387) 247010, Fax (01387) 259247

113

Appendix

GEOLOGICAL CONSERVATIONREVIEW SERIES

Benton, M.J. and Spencer, P.S. (1995) FossilReptiles of Great Britain. GCR Series No.10,Chapman & Hall, London, 386pp.

Bridgland, D.R. (1994) Quaternary of the Thames.GCR Series No.7, Chapman & Hall, London,441pp.

Campbell, S. (ed.) (in press) Quaternary of South-west England. GCR Series, Chapman & Hall,London.

Campbell, S. and Bowen, D.Q. (1989) Quaternaryof Wales. GCR Series No.2, NatureConservancy Council, Peterborough, 237pp.

Cleal, C.J. and Thomas, B.A. (1996) British UpperCarboniferous Stratigraphy. GCR SeriesNo.11, Chapman & Hall, London, 339pp.

Cleal, C.J. and Thomas, B.A. (1995) PalaeozoicPalaeobotany of Great Britain. GCR SeriesNo.9, Chapman & Hall, London, 295pp.

Emeleus, C.H. and Gyopari, M.C. (1992) BritishTertiary Volcanic Province. GCR Series No.4,Chapman & Hall, London, 259pp.

Floyd, P.A., Exley, C.S. and Styles, M.T. (1993)Igneous Rocks of South West England. GCRSeries No.5, Chapman & Hall, London, 256pp.

Gordon, J.E. and Sutherland, D.G. (eds) (1993)Quaternary of Scotland. GCR Series No.6,Chapman & Hall, London, 695pp.

Gregory, K.J. (ed.) (in press) FluvialGeomorphology of Great Britain. GCRSeries, Chapman & Hall, London.

Smith, D.B. (1995) Marine Permian of England.GCR Series No.8, Chapman & Hall, London,205pp.

Treagus, J.E. (ed.) (1992) Caledonian Structures inBritain: South of the Midland Valley. GCRSeries No.3, Chapman & Hall, London, 177pp.

Waltham, A.C., Simms, M.J., Farrant, A.J. and Goldie,H.S. (in press) Karst and Caves of GreatBritain. GCR Series, Chapman & Hall, London.

These volumes, with the exception of Quaternaryof Wales, can be bought from Chapman & Hall, 2–6Boundary Row, London SE1 8HN. Quaternary ofWales is available from Earth Science Branch,JNCC, Monkstone House, City Road,Peterborough, PE1 1JY.

REFERENCES

Boulton, G.S. and Paul, M.A. (1976) The influenceof genetic processes on some geotechnicalproperties of glacial tills. Quarterly Journal ofEngineering Geology, 9, 159–94.

Buckland, W. (1824) Notice on the Megalosaurus,or great fossil lizard of Stonesfield.Transactions of the Geological Society ofLondon, Series 2, 1, 390–6.

Clarkson, E.N.K., Milner, A.R. and Coates, M.I.(1994) Palaeoecology of the Visean of EastKirkton, West Lothian, Scotland. Transactionsof the Royal Society of Edinburgh, EarthSciences, 84, 417–25.

Conservation Committee of the Geological Society

References and further reading

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116

(1984) Record of the Rocks. (Leaflet availablefrom the Geological Society, BurlingtonHouse, Piccadilly, London W1V 9AG.)

Duff, K.L., McKirdy, A.P. and Harley, M.J. (1985)New Sites for Old. Nature ConservancyCouncil, Peterborough.

Dunning, F.W., Mercer, I.F., Owen, M.P., Roberts,R.H. and Lambert, J.L.M. (1978) BritainBefore Man. HMSO for the Institute ofGeological Sciences, London, 136pp.

Edmonds, E. (1983) The Geological Map. HMSO forthe Institute of Geological Sciences, London.

Gass, I. G, Smith, P. J. and Wilson, R.C.L. (eds)(1971) Understanding the Earth, ArtemisPress, 355pp.

Geologists’ Association. A Code for GeologicalFieldwork. (Leaflet available from theGeologists’ Association, Burlington House,Piccadilly, London W1V 9AG.)

Grayson, A. (1993) Rock Solid. Natural HistoryMuseum, London, 72pp.

Lovell, J.P.B. (1977) The British Isles throughGeological Time, a Northward Drift. GeorgeAllen & Unwin, London.

National Caving Association (1995) CaveConservation Policy. National CavingAssociation, London.

Nature Conservancy Council (1990) Earth ScienceConservation in Great Britain — A Strategyand Appendices — A Handbook of EarthScience Conservation Techniques. NatureConservancy Council, Peterborough.

Rickards, R.B. (1993) Graptolites. In TheEncyclopedia of the Solid Earth Sciences (ed.P. Kearey). Blackwell Scientific, Oxford, 713pp.

Wilson, R.C.L. (ed.) (1994) Earth HeritageConservation. The Geological Society,London in association with The OpenUniversity, Milton Keynes, 272pp.

Wyllie, P.J. (1976) The Way the Earth Works. JohnWiley & Sons Ltd, New York, 296pp.

FURTHER READING

Stratigraphy

General reading

Hecht, J. (1995) The Geological Timescale. InsideScience Number 81. New Scientist, 20 Maypp.1–4.

Technically advanced level

Salvador, A. (ed.) (1994) InternationalStratigraphic Guide: a Guide to Stratigraphic

Classification, Terminology and Procedure,2nd edition. International Union of GeologicalSciences and the Geological Society ofAmerica, Boulder, Colorado, USA.

Whittaker, A., Cope, J.C.W., Cowie, J.W. et al.(1991) A guide to stratigraphical procedure.Geological Society of London Special ReportNo. 20, Journal of the Geological Society,London, 148, 813–24.

Geology and the geology of Britain

General reading

An invaluable reference book covering all aspectsof Earth heritage conservation is provided byWilson (ed.) (1994), details of which are providedin the reference list. A personal account of theconnections between the geological history ofBritain and its landscapes is given by Fortey, R.(1993) The Hidden Landscape: A Journey into theGeological Past. Pimlico, London (paperback)310pp. It is an extremely readable follow-up to theintroduction given in Chapter 3 of this book.

A series of booklets available from the NaturalHistory Museum (Earth Galleries), ExhibitionRoad, London SW7 5BD, provide a valuable sourceof information about geology. Titles include:British Fossils (three volumes), Volcanoes, RockSolid and Britain’s Offshore Oil and Gas(published by United Kingdom Offshore OperatorsAssociation).

Titles available from the British Geological Surveyinclude the Holiday Geology Guides series andDiscovering Geology cards. They are availablefrom British Geological Survey, Kingsley DunhamCentre, Keyworth, Nottingham NG12 5GG;Murchison House, West Mains Road, EdinburghEH9 2LF and BGS London Information Office,Natural History Museum (Earth Galleries),Exhibition Road, London SW7 2DE.

In 1993, Scottish Natural Heritage launched a newseries of booklets entitled Landscape Fashionedby Geology. The series is produced in associationwith the British Geological Survey and describesthe geology of Scotland in relatively simple terms.Titles include Edinburgh, Skye, Cairngorms andLoch Lomond to Stirling.

The former Nature Conservancy Council publishedtwo booklets in the ‘Making of Modern Britain’series:

Nield, T., McKirdy, A.P. and Harley, M.J. (1989) TheAge of Ice. No. 1.

Nield, T., McKirdy, A.P. and Harley, M.J. (1990)Death of an Ocean. No. 2.

Advanced level

The British Geological Survey (addresses above)publishes and sells geological maps and regionalgeological summaries and memoirs to accompanymap sheets.

Two volumes covering the geology of the whole ofBritain have been published by the GeologicalSociety, London, and are available from GeologicalSociety Publishing House, Unit 7, BrassmillEnterprise Centre, Brassmill Lane, Bath BA1 3JN:

Craig, G.Y. (1991) Geology of Scotland, 3rdedition. 612pp.

Duff, P.,McL. D. and Smith, A.J. (ed) (1992)Geology of England and Wales. 651pp.

Earth heritage and natureconservation

The reference book Earth Heritage Conservation(Wilson, 1994 — see reference list) covers allaspects of the topic. It is available from theGeological Society Publishing House (theaddress is provided above). Earth ScienceConservation in Great Britain — a Strategyand Appendices — A Handbook of EarthScience Conservation Techniques is availablefrom the Headquarters offices of the countyconservation agencies (see Appendix). Otherpublications include:

Earth Heritage (previously named Earth ScienceConservation) A twice-yearly journal coveringthe wide issues relevant to geological andgeomorphological conservation. Available fromEnglish Nature (see address in Appendix).

Geologists’ Assocation (1989) Take Care WhenYou Core. (Leaflet available from theGeologists’ Association, Burlington House,Piccadilly, London W1V 9AG.)

Glasser, N.F. and Barber, G. (1995) Caveconservation plans: the role of English Nature.Cave and Karst Science, 21 (2), 33–6.

Nature Conservancy Council/English Nature(1991–1992) produced several leaflets onEarth heritage conservation principles,including Conserving our Heritage of Rocks,Fossils and Landforms; Fossil collecting andconservation; Regionally ImportantGeological/geomorphological Sites; and theseries “Earth Science conservation for ...” (forLandfill Managers; for Farmers andLandowners; for the Mineral ExtractionIndustry; for Quarry and Pit Managers; forDistrict Planners; for Coastal Engineers, andfor Wildlife Trusts).

O’Halloran, D., Green, C., Harley, M., Stanley, M.and Knill, J. (eds) (1994) Geological andLandscape Conservation. The GeologicalSociety, London. (Proceedings of the MalvernInternational Conference on Geological andLandscape Conservation, Great Malvern,1993.)

Prosser, C.D. (1992) Active quarrying andconservation. Earth Science Conservation, 31,22–4.

Prosser, C.D. (1992) Bartonian stratotype seriouslythreatened. Geology Today September-October, 163–4.

Prosser, C. D. (1994) The role of English Nature infossil excavation. Geological Curator, 6 (2),71–4.

Stevens, C., Gordon, J.E., Green, C.P. andMacklin M.G. (eds) (1994) Proceedings ofthe Conference Conserving our Landscape,Evolving Landforms and Ice-age Heritage,Crewe, 1992. Available from EnglishNature.


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Alpine Orogeny: A period of mountain buildingresulting from the collision of the Europeanand African plates which took place duringthe late Tertiary Period.

Ammonite: An extinct marine cephalopod mollusc;most forms had a tightly coiled, planispiralshell. Modern relatives include Nautilus andsquids.

Andesite: A volcanic rock, intermediate incomposition between basalt and rhyolite.

Anticline: An arch-shaped fold, with youngerstrata on the outermost part of the arch.

Aplite: A fine-grained, often light-coloured,intrusive igneous rock with high silicacontent, found in veins and dykes associatedwith granite intrusions. Aplites have acharacteristic ‘sugary’ texture.

Arthropod: A group of invertebrates which have asegmented body and jointed limbs and anexternal skeleton (e.g. insects, spiders andcrustaceans).

Axis (plural ‘axes’): In botany, main stem or root.Back reef: The area lying landward of a reef.Bar: A more or less linear ridge of sand and/or

gravel.Basalt: A fine-grained, usually dark-coloured,

crystalline igneous rock, with a silica contentless than 53% by weight.

Batholith: A large, irregular mass of igneous rockemplaced deep in the Earth’s crust.

Bed: A layer within a sequence of sedimentaryrocks defined by planar to irregularboundaries representing an originaldepositional surface.

Belemnite: An extinct marine cephalopod mollusc,

which possessed a bullet-shaped internalcalcium carbonate shell. Modern relativesinclude Nautilus and squids.

Bioherm: A mound-shaped build-up of mainly iinnssiittuu colonial organisms.

Biostratigraphy: The stratigraphical sub-divisionand correlation of sedimentary rocks based ontheir fossil content.

Biostrome: A sheet-like accumulation of fossilshells that are preserved in their life positions.

Bivalve: A class of mollusc that has two shells(valves) held together at a hinge area.Typically, the valves are symmetrical at theplane of the junction between them.Examples are oysters and mussels.

(GCR) Block: The classification unit used to selectand describe sites characteristic of thegeology of Great Britain.

Boulder clay: Poorly sorted, unstratified sediment,with grains ranging in size from rock ‘flour’ toboulders, deposited beneath glaciers and icesheets, or from melting ice. Also referred to as‘till’.

Brachiopod: A marine organism which has twoshells (valves) held together at the hingearea. Typically the valves are dissimilar, theplane of symmetry being at right angles tothe plane of junction between the valves (c.f.bivalves).

Breccia: A coarse-grained sedimentary rockconsisting of angular fragments.

Bryozoan: Type of aquatic colonial organism(normally marine) comprising individualsliving in linked box-like skeletons composedof calcium carbonate.

Glossary

119

Glossary

Caledonian Orogeny: A major period of mountainbuilding which took place during the LowerPalaeozoic sub-Era, associated with theclosure of the ancient Iapetus Ocean situatedbetween ‘Scotland’ and the rest of present-dayBritain.

Cambrian: The first geological period of thePalaeozoic Era (ranging from 570 to 510million years ago). It contains the oldestfossils of organisms with mineralisedskeletons.

Carbonate rocks: Rock formed mostly fromcarbonate minerals such as calcite (CaCO3)and dolomite (CaMg(CO3)2).

Carboniferous: The geological period ranging from345 to 280 million years ago of the UpperPalaeozoic sub-Era.

Cauldron subsidence: A collapsed area of avolcanic crater surrounded by circularigneous dykes.

Cenozoic: The youngest era of geological timespanning from approximately 65 million yearsago to the present, consisting of the Tertiaryand Quaternary periods.

Cephalopod: A class of marine mollusc whichincludes the extinct ammonites andbelemnites, and the living squid, cuttlefish,octopus and Nautilus.

Chert: A fine-grained silica-rich rock occurringwithin sedimentary and volcanic rocks.

China clay: Deposit of the mineral kaolin,produced by the alteration of granite by hotfluids deep in the Earth’s crust, or by surfaceweathering.

Chronostratigraphic unit (Time-rock unit): Asequence of rocks deposited during aparticular interval of geological time.Historically, time-rock units were definedbefore the units in the geological time scale.Geological time scale units were actuallybased on time-rock units, rather than theother way round as suggested by thedefinition. For example, sediments laid downduring the Ordovician Period (a geologicaltime unit) belong to the Ordovician System (achronostratigraphic unit). The hierarchy ofchronostratigraphic units consists of erathem(equivalent to era), system (period), series,stage and chronozone.

Cirque: A deep, steep-walled hollow in a mountaincaused by glacial erosion; equivalent to corriein Scotland and cwm in Wales.

Clast: A fragment of rock or a mineral grainresulting from the erosion and transport of

weathered rock material.Clay: A sediment composed of extremely small

grains less than four thousandths of amillimetre across.

Conglomerate: A very coarse-grained sedimentconsisting of rounded clasts.

Conservation: Protection, preservation and carefulmanagement of natural resources and theenvironment.

Contact: The junction between two different rocktypes. The term is often used to describe thejuxtaposition of igneous and sedimentaryrocks and the associated metamorphism ofthe latter (‘contact metamorphism’).

Continental crust: The part of the Earth’s crust thatlies beneath the continents and continentalshelves and that has a density 2.7 to 3.0 timesthat of water. It varies in thickness from 25 to70 kilometres.

Continental drift: The relative movement of thecontinents during Earth history.

Core: The central part of the Earth below a depthof 2900 kilometres, thought to be composedof a mixture of nickel and iron.

Correlation: In stratigraphy, the establishment of acorrespondence between stratigraphic unitsusing either similarities in rock type or fossilcontent. Isolated sequences of rock may becorrelated as being once physicallycontinuous units, or deposited during thesame span of time.

Country rock: The rock intruded by a plutonicigneous rock.

Cretaceous: The last period of the Mesozoic Era,ranging from 140 to 65 million years ago.

Crust: The thin outermost solid layer of the Earth.It varies in thickness from about 5 kilometres(beneath the oceans) to 30–70 kilometres(beneath the continents).

Cryoturbation: Movements of the ground causedby seasonal freezing and thawing above apermanently frozen zone.

Cupola: A small dome-like protuberance projectingfrom the main body of an igneous intrusion.

Cuticle: Outer protective ‘skin’ covering the aerialparts of most land plants. It helps to reducewater loss.

Cyano-bacteria: Blue-green algae; micro-organismscapable of photosynthesising. Fossil formshave been found in rocks more than 3000million years old.

Debris dyke: A crevasse-like feature in the icesurface filled with glacial debris.

Denudation: The combined processes of

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weathering and erosion that wear downlandscapes. From the Latin denudare, to ‘stripbare’.

Deposition: The accumulation of sediment inaqueous or subaerial environments.

Devonian: The first period of the Upper Palaeozoicsub-Era, ranging from 395 to 345 million yearsago.

Dolerite: A medium-grained intrusive igneous rockwhich has the same chemical andmineralogical composition as extrusive basaltand plutonic gabbro.

Dolomite: A mineral composed of calcium-magnesium carbonate, or a rock composed ofthis mineral. Many dolomitic rocks arelimestones that were ‘dolomitised’ by theaction of groundwater solutions rich inmagnesium.

Drift deposits: Sediments deposited from rivers,glaciers and ice sheets overlying oldergeological formations. Geological maps arereferred to as ‘drift maps’ when they showsuch deposits, or as ‘solid maps’ when thesedeposits are omitted.

Drumlin: A streamlined, oval-shaped hillcomposed of boulder clay (and occasionallysolid rock). Its long axis is parallel to thedirection of flow of the ice sheet beneathwhich it formed.

Dyke: A sheet-like body of igneous rock that cutsacross the bedding of the rocks it intrudes; itis often steeply inclined.

Earth heritage: The inheritance of rocks, soils andlandforms (active and relict) and the evidencethey contain that enables the history of theEarth to be unravelled.

Earth science: The applications of the principlesand methods of mathematics, biology,chemistry, physics and those special to Earthscience, to the study of the Earth and theelucidation of its history.

Echinoderm: Marine animals usually characterisedby a five-fold symmetry, and possessing aninternal skeleton of calcite plates and acomplex water vascular system. Includesechinoids (sea urchins), crinoids (sea lilies)and asteroids (starfish).

Ecosystem: A system that encompasses theinteractions between a community oforganisms and its surrounding environment.

Eon: The largest unit of geological time, dividedinto eras.

Era: A large unit of geological time composed ofseveral periods. The Phanerozoic Eon is

divided into the Palaeozoic, Mesozoic andCenozoic eras, and their constituent periodsare defined on the basis of their characteristiccontent of invertebrate, vertebrate and plantfossils.

Erosion: The process of wearing away the Earth’ssurface through the removal of rock debris bywater, wind and ice.

Erratic: A large clast left behind by melting ice andcomposed of rock not found locally.

Esker: A sinuous ridge of sand and graveldeposited by a meltwater stream flowingwithin a tunnel under a glacier or ice sheet.

Evaporite: A general term used to describesediments that formed by the precipitation ofsalts due to the evaporation of sea or lakewater.

Exposure sites: Sites whose scientific oreducational value lies in providing surfaceexposures of geological features that areextensive or plentiful underground, but areotherwise not visible (e.g. coastal cliffs,quarries).

Extrusive rock: Igneous rock that originallyerupted as a liquid (magma) at the Earth’ssurface.

Fault: A fracture in the Earth’s crust along whichrock units were displaced relative to oneanother.

Fauna: Animal life of a region or environmenttoday, or in the past.

Feldspar: A group of aluminium-silicate rock-forming minerals. They are the most abundantminerals in the Earth’s crust.

Fluvial: Relating to a river or river system.Fold: A bend in rock strata produced by earth

movements.Fossil: The preserved remains or traces of once-

living animals and plants.Gabbro: A coarse-grained, often dark-coloured

plutonic igneous rock. Gastropod: A class of marine, freshwater and

terrestrial molluscs which live in a single shellthat is usually coiled.

GCR: Geological Conservation Review, in whichnationally important geological andgeomorphological sites were assessed andselected with a view to their long-termconservation.

Geology: The study of the Earth, its origins,structure, composition and history (includingthe development of life), and the nature of theprocesses that have given rise to its presentstate.

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Geomorphology: The study of landforms and theprocesses that formed them.

Glacier: A large body of ice occupying corries anda valley in a mountainous area, and whichmoves slowly under the influence of gravity.

Glaciofluvial sediments: Sands and gravelsdeposited from meltwater streams associatedwith ice sheets and glaciers.

Glaciolacustrine: Sediments deposited in lakesmarginal to a glacier.

Glaciotectonic: Deformation of rocks or sedimentscaused by glacial movement.

Gneiss: A coarse-grained metamorphic rock,composed of alternating light and dark bands,formed at very high temperatures andpressures.

Granite: A coarse-grained plutonic igneous rockrich in silica, consisting largely of feldspar andquartz.

Granodiorite: A coarse-grained igneous rocksimilar to granite in texture but containingslightly less silica.

Graptolite: Extinct colonial planktonic animals,distantly related to chordates; widely used forPalaeozoic stratigraphical correlations.

Greywacke: A sandstone containing more than 15%clay between the constituent clasts.

Gypsum: Hydrated calcium sulphate, oftenoccurring as an evaporite mineral.

Hornfels: A hard, fine-grained, splintery rock,resulting from the baking of sediments incontact with magma.

Hydrocarbons: Naturally occurring organiccompounds containing hydrogen and carbon,such as natural gas, oil and bitumen.

Hydrothermal activity: Processes associated withigneous activity that involve heated orsuperheated water.

Ice Age: Popular name often given to theQuaternary Period during which large areaswere repeatedly covered by ice sheets andglaciers.

Ice cap: An area of ice, smaller than an ice sheet,occurring in the polar regions and highmountains.

Ice foliation: Thinly bedded layering in the ice.Ice sheet: Very large areas of ice, such as those

covering much of Greenland and Antarcticatoday. During the Quaternary, ice sheetscovered much of the Northern Hemisphere.

Igneous rocks: Rocks formed from molten rock(magma). They usually consist of interlockingcrystals, the size of which is dependent on therate of cooling (slow cooling gives larger

crystals; rapid cooling produces small crystals).IInn ssiittuu: Latin ‘in place’, used to describe features

and fossils found where they were formed.Integrity sites: Sites whose scientific or

educational value lies in the fact that theycontain finite and limited deposits orlandforms that are irreplaceable if destroyed.

Interglacial: A period of relatively warm climatebetween two episodes of glaciation.

Intrusive rock: Rock which, in the molten state,was forced into (‘intruded’) pre-existing rocksand solidified without reaching the surface.

IUGS: International Union of Geological Sciences.JNCC: Joint Nature Conservation Committee.Joints: A fracture in a rock that exhibits no

displacement across it (unlike a fault). Jointsmay be caused by the shrinkage of igneousrocks as they cool in the solid state, or, insediments, by the regional extension orcompression of sediment caused by earthmovements.

Jurassic: The middle of the three periods of theMesozoic Era, ranging from 195 to 140million years ago.

Kame: A mound of sand and gravel originallydeposited on top of a glacier or ice sheet bymeltwaters, and remaining as a topographicfeature after the ice melted.

Karst: Landscape produced by the dissolution oflimestones by percolating groundwaters andunderground streams. Named after the Karstregion of the former Yugoslavia.

Kettle hole: A depression in glacial or glaciofluvialsediments, resulting from the melting of amass of glacier ice that was buried insediment.

Landform: A natural feature of the surface of theland.

Lava: Molten rock extruded onto the Earth’ssurface, or the resultant solid rock.

Limestone: A sedimentary rock composed ofcalcium carbonate (calcite), often derivedfrom the shells of organisms.

Limestone pavement: A bare limestone surfaceformed by solution processes that enlargejoints to produce ridges (‘clints’) and clefts(‘grykes’).

Lithification: A general term used to describe theconversion of sediment into rock.

Lithology: The term encompassing the colour, sizeand shape of constituent crystals or clasts, andthe mineral composition of a rock.

Lithostratigraphy: The stratigraphical sub-divisionand correlation of sedimentary rocks based on

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their lithological features.Lodgement till: A glacial deposit laid down

underneath an ice sheet or valley glacier. It isusually clay-rich and contains boulders.

Machair: Dune pasture with lime-rich soil.Magma: Molten rock; referred to as lava when

extruded onto the Earth’s surface.Maniraptor: A group of small, bipedal carnivorous

dinosaurs.Mantle: The layer of the Earth’s interior situated

between the core and the crust. It is about2300 kilometres thick.

Marl: A calcareous clay or mudstone.Mass extinction: The dying-out of several plant

and/or animal groups over a brief period ofgeological time.

Mass movement: The down-slope movement ofrock debris or sediment under the influenceof gravity.

Mesozoic: The middle of the three eras thatconstitute the Phanerozoic Eon. Literalmeaning is ‘middle life’, it spans the Triassic tothe Tertiary, from 230 to 65 million years ago.

Metallogenetic: Containing metallic mineraldeposits or ores.

Metamorphic rocks: Rocks which have beenchanged in the solid state by heat and/orpressure, without melting. They may originallyhave been either igneous or sedimentary rocks.Examples include slate (changed from clay) andmarble (originally limestone).

Mineral: A naturally occurring chemicalcompound or element.

Mineralogy: The study of minerals.Molluscs: Invertebrates with a fleshy soft body

and, usually, a hard shell. May be marine,freshwater or terrestrial; includes gastropods(snails, limpets), bivalves (oysters, mussels),cephalopods etc.

Moraine: Ridges of unsorted, unstratified glacial tilldeposited on top of or at the margins of aglacier or ice sheet.

NNaauuttiilluuss: A living cephalopod mollusc with acoiled external shell, related to the squid andoctopus.

NCC: Nature Conservancy Council.(GCR) Network: A conceptual framework of

geological characteristics which encompassesthe Earth science features of a block; a blockmay contain one or more networks.

New Red Sandstone: A sequence of red, largelydesert and fluvial sediments, which wereformed in Britain after the CarboniferousPeriod, but before the Jurassic.

Oceanic crust: The part of the Earth’s crust that liesbeneath the ocean basins, varying in thicknessbetween 6 and 11 kilometres, and composedlargely of basalt and gabbro.

Oil shale: A dark-grey or black shale whichcontains organic substances that yieldhydrocarbons, but does not contain freepetroleum.

Old Red Sandstone: A sequence of red continental(largely fluvial) sediments in Britain ofDevonian age.

Ooid: A spherical/ subspherical carbonate-coatedsedimentary particle, less than 2 millimetresin diameter.

Ordovician: The second period in the PalaeozoicEra, ranging from 510 to 439 million years ago.

Ore: A mineral or rock that can be exploitedcommercially.

Orogeny: A mountain-building period, duringwhich continental crust is thickened byprocesses associated with the closing ofoceans and subsequent collision betweencontinents.

Outcrop: An area of rock which is naturallyexposed at the Earth’s surface.

Outwash sediments: Sands and gravels depositedby streams beyond the ice margin. Thesestreams originate within and beneath the ice,and transport the sediments to locations‘outside’ the margin.

Palaeobotany: the study of the fragmentaryfossilised remains of plants.

Palaeochannel: A ‘fossil’ river or tidal channel (i.e.one that is no longer active).

Palaeontology: The study of fossil fauna and flora,including their evolution and reconstructionof past animal communities and ancientenvironments.

Palaeozoic: The first of the three eras of thePhanerozoic Eon. Literal meaning ‘old life’, itspans the Cambrian to the Permian periods,from 570 to 230 million years ago. The era issometimes divided into sub-eras, the LowerPalaeozoic (Cambrian to Silurian Periods) andthe Upper Palaeozoic (Devonian to Permianperiods).

Pangaea: A supercontinent that existed more than200 million years ago, before beingfragmented by continental drift.

Patch reef: An isolated body reef or body of reef rock.Pegmatite: A very coarsely crystalline igneous

rock, with crystals greater than 3 centimetresin length that formed during the final stages ofcooling of a large volume of magma.

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Peridotite: A coarsely crystalline, silica-poor,igneous rock consisting predominantly of themineral olivine. The Earth’s mantle isprobably composed largely of peridotite.

Periglacial: A term applied to the region adjacentto a glacier. The ground is largely permanentlyfrozen, but may thaw during the summer.

Period: A geological time scale unit (c.f. system, achronostratigraphic (time-rock) unit).

Permian: The last period of the Palaeozoic Era,ranging from 280 to 230 million years ago.

Petrology: The study of the composition,occurrence and origin of rocks.

Phanerozoic: An eon comprising the Cenozoic,Mesozoic and Palaeozoic eras.

Photosynthesis: The process by which the energyof sunlight is used by organisms, especiallygreen plants, to synthesise carbohydrates fromcarbon dioxide and water.

Pillow lava: Rounded masses of basaltic lavaformed by extrusion under water.

Plate: A rigid ‘slab’ of the Earth’s crust anduppermost mantle that moves relative to otherplates.

Pluton: A general term for a deep-seated igneousintrusion, irrespective of its size.

Precambrian: An informal term to encompass all ofthe time that precedes the Phanerozoic Eon(i.e. 4600 to 570 million years ago).

Prograding shoreline: The seaward migration of ashoreline.

Proterozoic: The second eon of geological time,forming the later part of the ‘Precambrian’.

Quartz: A mineral composed entirely of silica.Quartzite: A metamorphic rock formed from pure

quartz sandstones.Quaternary: The latest period of geological time,

from 1.6 million years ago to the present. (See‘Ice Age’.)

Radiometric dating: Methods of dating certainrocks or minerals using the relativeabundances of radioactive and stable isotopesof certain elements, together with knownrates of decay of radioactive elements.Radiocarbon dates extend back to only 50,000years, but other elements (potassium, lead,uranium) are used to obtain dates in the orderof tens to thousands of millions of years.

Raised beach: A former beach now situated abovethe level of the present shoreline as a result ofearth movement or changes in global sea levelor land level.

Reef crest: The top of the seaward slope of a reef.Reef flat: The relatively flat area behind the reef

crest.(Marine) Regression: The withdrawal of water

from parts of the land surface as a result of afall in sea level relative to the land.

Relict: Descriptive of a geological feature survivingin its primitive form.

Rhyolite: A fine-grained lava, having the samechemical and mineralogical compositions asgranite.

RIGS: Regionally Important Geological/geomorphological Sites.

Rock: A mass of mineral matter that may or maynot be lithified.

Roof pendant: A mass of country rock immediatelyabove an igneous rock body.

Sabkha: The Arabic word for a wide area of coastalflats bordering a lagoon. Evaporite mineralsare formed in such areas.

Sandstone: A sedimentary rock made of lithifiedsand.

Sauropod: Quadrapedal, herbivorous dinosaurs ofthe Jurassic and Cretaceous periods. Examplesinclude Diplodocus and Brachiosaurus.

Schist: Metamorphic rock characterised by theparallel alignment of constituent minerals,commonly the platy mineral mica.

Scree: See ‘Talus’.Sediment: Loose material derived from the

weathering and erosion of pre-existing rocks,from biological activity (e.g. shells and organicmatter) or from chemical precipitation (e.g.evaporites).

Sedimentary rocks: Formed from the lithification(cementation) of sediment. Sedimentary rocksmay be composed of mineral or rock particles(clasts) to form sandstones and claystones orsediments, of biological origin to formlimestone and peat, or of chemicalprecipitation to form evaporites.

Shale: A fine-grained sedimentary rock composedof clay particles that splits easily into thinlayers.

Silica (silicate): Silicon dioxide. (Mineralconsisting of or incorporating silica.)

Sill: A sheet-like body of igneous rock which, ingeneral, does not cross-cut the layering of therocks that it intrudes.

Silurian: The third period of the Palaeozoic Era,ranging from 445 to 395 million years ago.

Slate: A fine-grained metamorphic rock formedfrom clays and shales. The alignment of platyminerals during metamorphism enables therock to be split easily along planar surfaces notnecessarily parallel to the bedding within the

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original sediment.Soil creep: Gradual movement of wet soil on a

slope, moving under the influence of gravity.Spit: An elongate deposit of sand or gravel

projecting obliquely seawards from ashoreline.

SSSI: Site of Special Scientific Interest.Stage: A chronostratigraphic (time-rock) unit.Stegosaur: A Jurassic/Cretaceous quadrapedal

dinosaur characterised by a double row ofprotective bony plates along its back.

Stomata: Minute pores in the surface of a leafthrough which gas and vapour may pass.

Strata (Singular: stratum): Layers withinsedimentary rocks. The term is often usedinstead of beds.

Stratigraphical unit: A body of rock defined by itslithological features (lithostratigraphical unit)or fossil content (biostratigraphical unit).

Stratigraphy: The study of rock strata and theirdistribution in space and time.

Stratotype (type section): A seqence ofsedimentary rocks at a particular localitychosen as the standard against which othersequences can be compared. Stratotypes areestablished for lithostratigraphical andbiostratigraphical units, both regionally andinternationally. See stratigraphical unit.

Stromatolite: A laminated mounded structurecomposed of limestone built by cyano-bacteria. Stromatolites form today in warmshallow tropical seas. They appear in theearly Precambrian.

Subduction: Process whereby one plate made upof oceanic crust is carried down into themantle beneath another plate.

Superglacial (Sometimes, ‘supraglacial’): Literally‘over’ or ‘upon’ the ice. Thus superglacialdeposits are those that accumulated on the icesurface. When the ice disappears they are lefton the land surface, frequently forminghummocks of sand, gravel and clay.

Sustainability: The concept of meeting the needsof the present without compromising theability of future generations to meet theirneeds. In nature conservation terms, it refersto the use of a natural resource in a way whereit can be renewed, such that theenvironment’s natural qualities aremaintained.

Talus: The accumulation of rock fragments at thefoot of a cliff. Also called scree.

Taxon (Plural: taxa): Any unit of classification oforganisms (e.g. phylum, class, order, family,genus, species).

Tectonism (Adjective: tectonic): Deformation ofthe Earth’s crust and the consequentstructural effects (e.g. faulting, folding etc.).

Tertiary: The penultimate geological period,ranging from 65 to 1.6 million years ago.

Till: Synonymous with boulder clay.Tombolo: A bar or spit of sand or shingle, linking

an island to the mainland or another island.(Marine) Transgression: An advance of the sea

over land, due to movements of the Earth’scrust or to a global rise in sea level.

Triassic: The first period of the Mesozoic Era,ranging from 230 to 195 million years ago.

Trilobite: An extinct class of marine arthropods.Tuff: A lithified volcanic ash.Type area/locality: The location where the type

section (or stratotype) for a stratigraphicalunit is located, or where the original typesection or fossil was first described. Forexample, Kimmeridge Bay in Dorset is thetype locality for the Kimmeridge ClayFormation (a lithostratigraphic unit).

Unconformity: The surface that separates twosedimentary sequences of different ages; itrepresents a gap in the geological recordwhen there was erosion and/or no deposition.There is often an angular discordancebetween the two sequences.

Variscan Orogeny: A mountain-building episodethat occurred during the late CarboniferousPeriod in south-west England, South Walesand southern Ireland.

Vascular tissue: Living matter made up of, orcontaining, vessels that convey blood or sap,which transport nutrients etc.

Vent: The opening within a volcano through whichigneous material is ejected.

Volcanic rocks: Lavas, ashes and near-surfaceigneous intrusions associated with volcanoes.

Weathering: The process by which rocks arebroken down in place by physical, chemicaland biological processes.

Xenolith: A piece of pre-existing rock found withinan igneous rock, often composed of pieces ofcountry rock into which magma was intruded.

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Page numbers in bold type referto figures and page numbers initalic type refer to tables.

A Active geomorphological

process site conservation51, 89, 97–8, 97

Agassiz, Louis 39, 41Alpine Orogeny 3, 22, 34, 51,

70Ammonites 19, 34, 51Amphibians, prehistoric 3, 28,

30, 71, 79Ancient environments 8, 13,

13–14, 19, 25–37, 27–32,39, 50, 52–6, 52, 54–5,58, 61–6, 84, 87, 93, 96,98

Anglesey 26, 26Anglian glaciation 35, 64,

65–6, 72, 83Anning, Mary 40, 41Antrim 34Archaean Eon 17, 18Archaeology 65, 86, 95Ardnamurchan Peninsula 34Arran 34Arthropods 26, 28, 50, 51, 71Arthur’s Seat, Edinburgh 13,

13Ashdown Forest, Sussex 40

BBailey, Edward 48Barton Cliffs, Hampshire 14,

14, 91Basalt 17, 23–4, 23, 33, 61Batholiths 57–9, 57–60Beach–dune–machair system

66–9, 68Beach complexes 66–9Biozones 47Birds, prehistoric 3, 14, 34, 51,

71Bodmin Moor Granite 58,

59–60Borrowdale Volcanic Group,

Lake District 29Boulder clay 34, 36, 64, 78Boxgrove, West Sussex 35Brighstone Bay, Isle of Wight

96, 97Britain,

geological history 3, 13–41geology 14–22, 16

British Association for theAdvancement of Science41

British Geological Survey 41,104

British reference sections 7, 7,14, 14, 45, 46–7, 56,69–72, 83

Buckland, Professor William40–1, 48

C Caledonian Orogeny 22, 22,

25, 25, 28, 51, 71Cambrian Period 18, 18, 25–8,

27, 39–40, 70, 93Carboniferous Limestone 31Carboniferous Period 18, 18,

27, 28–31, 29–31, 40,57–9, 61, 63, 66, 70–1,84, 84, 98

Cave conservation 72, 83, 89,95, 95

Cenozoic Era 17, 18, 18Chalk 18, 15, 20, 22, 33, 34,

49, 88, 93Charmouth, Dorset 19Charnwood, Leicestershire 7, 8Cheddar Gorge, Somerset 49Chesil Beach, Dorset 47, 49,

49Chiltern Hills 20, 22China clay 59–60Chronozones 47Claverley Road Cutting,

Shropshire 96, 96Climatic changes 7–9, 9, 34–5,

41, 52, 62, 64, 66, 104Coal 7, 18, 28, 29, 63Coastal conservation 4, 14, 14,

51, 66–9, 83, 91, 104Coastal geomorphology 3–4,

10, 14, 14–15, 31, 33, 37,

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Index

Index

128

37, 41, 49, 51, 66–9, 68,72, 78–9, 79, 83, 83, 88,99

Coastal Geomorphology ofScotland GCR Block66–9, 68, 72

Coastal processes 3–4, 8, 14,14, 37, 49, 51, 66–9, 83,88, 104–5

Continental crust 22–5, 23, 25,41

Continental drift 3, 22, 26, 27Coombs Quarry,

Buckinghamshire 86Coral reefs 28, 53Corton Cliff, Suffolk 83Country Parks 85Countryside Council for Wales

45–6, 85, 89, 103, 105County Naturalists’ Trusts 85Cretaceous–Tertiary boundary

34Cretaceous Period 18, 18, 20,

20, 27, 31, 33, 34, 40, 51,69, 71, 76, 77, 79

Croll, James 41Crustal rebound 9, 14, 15,

34–5, 41, 69

DDalradian metamorphic rocks

26, 51, 70Dartmoor Granite 3, 49, 58,

59–60Darwin, Charles 41de la Beche, Sir Henry 39Devonian Period 18, 18, 25, 27,

28–31, 39–40, 39, 49, 50,51, 57–63, 66, 70–1

Dinas Dinlle, Gwynedd 78Dinosaurs 3, 18, 32, 34, 40–1,

48, 96, 97Dob’s Linn, south-west Scotland 7Dolomitised limestones 53, 54,

56Drumlins 34, 36Duckmanton Railway Cutting,

Derbyshire 29Durham Province network,

Marine Permian Block52–3, 52, 55, 56

Durlston Bay, Dorset 77, 79, 79Dykes 17, 57, 60–1

E Early life-forms 3, 8, 18, 18, 26,

50Early humans 3, 9, 35, 64Earth heritage conservation

7–10, 83–99, 103–5active geomorphological

processes 97–8, 97caves 95, 95coastal sites 91developments 103–5fossil and mineral collecting

90–1guidelines 89–90, 105history 84–6international links 105management 84–90, 104–5promoting awareness 10, 85,

99, 99, 103–4quarries 83–4, 91–4road cuttings 96, 96strategy 88–90, 103techniques 104

Earth heritage publications 89,95, 97, 99, 103–4,115–17

Earth heritage sites 7–10, 7–10‘burial’ 98–9classification 88–90conservation 7–10, 83–99,

103–5cultural/ecological resource

10, 10documentation 88–9, 103–4education/training 9, 10excavation 96, 97exceptional 7–8, 8, 50international significance 7,

7legal protection 86–8management 84–90, 104–5

Earth heritage threats 83–4quarrying 83–4

Earth history 3, 7, 13–14, 18,19, 25, 27, 37–8

Earth science research 8, 9Earth structure 22–5, 23Earthquakes 8, 22–4, 24Earth’s crust 9, 14, 15, 22–6,

23–5, 34–5see also continental drift movements 15, 22–3, 25, 26,

57, 57, 69

thickening 22, 25, 25East Kirkton, Lothian 30, 49English Nature 45–6, 85, 89,

91, 97–8, 103, 105Environmental change 3, 9, 9,

27–8, 37, 51, 75Environmental forecasting 7–9,

9, 15Environmental Protection Act,

1990 85–6Eons 17, 18Epochs 18Eras 17, 18, 18Ercall Quarry, Shropshire 92,

93Erosion 4, 9, 13, 14, 15, 22, 25,

33, 37, 49, 59, 66–9, 68,83, 83, 88, 89–91, 98–9,104–5

Eskers 34, 36, 75, 89Evaporite deposits 31, 53, 54,

56Exmoor floods 37

FFaults in rocks 21, 24–5, 51,

66, 78 Fish, prehistoric 28, 32, 34, 39,

51, 71, 79, 93Floodplains 34, 64, 66, 98, 105Florence Mine, Cumbria 80Folding in rocks 20, 20, 22, 25,

31, 34, 51, 58, 78Forth Valley, Scotland 41Fossil collecting, conservation

90–1Fossil Grove, Glasgow 84, 84Fossils 7, 7, 9, 14, 17, 18, 19,

19, 26, 28, 30, 32, 34–5,37, 38–41, 40, 46, 47, 48,49, 50, 51, 53, 61, 63, 71,76, 84, 84, 86–7, 87,89–91, 93, 98, 98

classification 19preservation 19

GGalashiels, south Scotland 39Gault Clay 20GCR, 45–72GCR aims 45–9GCR blocks 49–69, 69–72GCR networks 52–69, 69–72

GCR publications 4, 45, 69,99, 103–4

GCR sites 45–9, 69, 69–72documentation 77, 78legal protection 86–8review procedures 77–8selection 45, 75–80, 78exceptional features 47–9international importance

45–7minimum number and size

76representativeness 49working methods 76–8within SSSIs 79, 79

Geikie, Archibald 41James 41

Geological maps 14–15, 16, 20,21, 25, 38–9, 58, 77

Geological periods 7, 16, 17,18, 18, 40, 61, 91

Geological Society of London38, 41, 85

Conservation Committee 85Geological Survey of Great

Britain 39Geological time 7, 14–15, 17,

18, 18, 27–8, 38, 49, 51Geologists’ Association 85, 90,

97–8Geomorphology GCR blocks

50–1, 72Geomorphological processes

33, 37, 41, 49, 51, 63–9,72, 79, 97–8

Geomorphology 33, 41, 45–7,49–51, 49, 63–9, 72, 79,89

Glacial deposits 9, 15, 34–7,36–7, 41, 64, 65, 66, 75,78

Glaciation 14, 15, 34–7, 35, 64,68–9

Glaciers 3, 14, 34, 35–6, 37,41, 65

Glencoe, Lochaber, Scotland47, 48

Granite 3, 17, 23, 23, 25, 25,28, 57–60, 57–9, 91–2,91–2, 105

Graptolites 26, 39, 40Gravel deposits 9, 34, 49,

64–6, 64, 78, 83, 91Great Glen Fault 21

HHartland Point, Devon 31Haytor Rocks, Dartmoor 3, 49,

60High Lodge, Suffolk 35Highland Boundary Fault 21Hornsleasow Quarry,

Gloucestershire 32Hunstanton Cliffs, Norfolk 88,

89, 99Hutton, James 13, 37–8, 38Hutton’s Unconformity, Siccar

Point, Berwickshire 38, 47Huxley, Sir Julian 85

IIapetus Ocean 26, 28Ice ages 9, 14–15, 15, 34–5, 37,

37, 41, 64, 66, 75, 104Ice sheets 9, 14, 15, 34, 37, 41,

51, 64, 65–6Ichthyosaurs 3, 34, 40, 48Igneous petrology GCR blocks

50–1, 71Igneous rocks 3, 13, 13, 15, 17,

17, 21, 23, 50, 57–6157–8, 69

extrusive 13, 17, 17, 23, 61intrusive 3, 13, 13, 17, 17, 23,

25–6, 48, 57–61, 57–9Igneous Rocks of South-west

England GCR Block 51,57–61, 57–9

Inner Hebrides 14, 15, 66Insects, prehistoric 3, 7, 19,

28, 50, 51, 71, 75, 98, 98Interglacial climates 34–5, 37,

64, 65, 66Iron ore deposits 80Islay 14, 15

J Jamieson,

Robert 41Thomas 41

Joint Nature ConservationCommittee (JNCC) 85,103

Jura 14, 15, 67Jurassic–Cretaceous Reptilia

Block 51, 77, 79Jurassic Period 16, 18, 18, 20,

20, 27, 31, 32, 34, 40, 41,48, 69–71, 86, 93

K Kame terraces 36, 75, 75, 89Karst sites 72, 89, 95Kettle holes 36Kildrummie Kames esker

system, Inverness District75, 75

Kimmeridge Bay, Dorset 10Kirtlington Quarry, Oxfordshire

93, 93

LLake District 28, 29, 71, 80Land plant evolution 3, 7–8,

10, 14, 19, 28, 31, 34–5,37, 50, 51, 61–3, 63, 84,84, 98, 97–8

Landfill site conservationschemes 45, 94, 94, 104

Landforms 7–8, 10, 13, 15,34–5, 35–6, 41, 47, 49,50–1, 64–9, 68, 72, 75,88–9, 88, 104–5

conservation 88–9, 98Land’s End Granite 58Landscape evolution 3, 7, 9,

34, 37, 41, 49–51, 83, 98,104–5

human activity 37, 83, 85,88, 105

Langdale Pikes, Lake District29

Lapworth, Charles 39Lava 3, 13, 17, 29, 33, 34, 59,

61, 66Lewisian Gneisses 26, 26, 51,

66, 70Limestone pavement 10, 85, 88Limestone Pavement Orders

85, 88Lizard and Start complexes

network 57–8, 58, 61Lummaton Hill Quarry SSSI,

Torquay, Devon 39Lyell, Charles 18, 38

Index

129

Lyme Regis, Dorset 40, 41

MMaclaren, Charles 41Magma 13, 15, 23–4, 57–9, 57,

92Malvern Hills 26Mammals, prehistoric 3, 14,

32, 34–5, 48, 71, 79Mantell,

Charles 40Mary Ann 40

Mantle 22–5, 23, 25Marine Permian GCR Block

52–6, 54–5, 70Mass extinction 34Mass-movement processes 37,

72Memorial Crags, Charnwood

Forest 8Mesozoic Era 17, 18, 18, 22,

71, 79Metamorphic rocks 15, 17, 22,

25–6, 26, 50–1, 57–9, 61,69, 70, 92

Mid-Atlantic Ridge 23, 23Miller, Hugh 39Mine dumps 80, 90, 98–9Mineral collecting, conservation

90–1Mineralogy GCR blocks 50, 52,

71, 80Moel Tryfan, Gwynedd 9Moine metamorphic rocks 26,

51, 70Moraine 36Morfa Harlech, Gwynedd 88,

89Mountain belts 3, 17, 20–2,

22–3, 25, 25, 28, 57–8, 57Mountain building 3, 21, 22–6,

25, 28, 29, 34, 51, 53,57–8, 57

Mull 34Murchison, Sir Roderick Impey

39, 39, 47

NNational Caving Association 95National Nature Reserves (NNR)

10, 85–7, 87National Parks 85

National Parks and Access tothe Countryside Act,1949 45, 85–6

National Rivers Authority 87National Scheme for Geological

Site Documentation 89Natural Areas 105Natural Heritage (Scotland) Act,

1991 85–6Natural History Museum 39Nature Conservancy 45, 85, 87Nature Conservancy Council

(NCC) 4, 45, 76–7, 85,94, 103

Nature conservation 45–6, 51,84–8, 93, 99, 104–5

Nature Conservation Orders46, 88

Nature Conservation Review 85Nature Reserves Investigation

Committee 84

OOcean ridges 24, 24Ocean trenches 23–4, 25Oceanic crust 22–4, 23–5, 61Oil shales 10Old Man of Storr, Skye 33Old Red Sandstone 28, 38, 39,

66, 71Ordovician Period 7, 18, 18,

26–8, 29, 40, 40, 57, 70–1Ore mineralisation 80Organic-rich rocks 10, 54, 63Orogenesis, see mountain

building Outer Hebrides 67Owen, Dr Richard 41Oxford Clay 40

PPacific Ocean 23–4Palaeontology GCR blocks

50–1, 70–1Palaeontology 19, 30, 50–1, 50,

70–1, 90Palaeozoic Era 17, 18, 18, 22,

61–2Palaeozoic Palaeobotany GCR

Block 61–2, 71Pangaea 26, 28, 31, 34Peak Cavern, Derbyshire 95

Peat deposits 9, 35, 47Periglacial environments 34,

66Permian Period 18, 18, 20, 27,

31, 40, 52–3, 52, 55, 56,59, 61, 63, 70–1

Phanerozoic Eon 17, 18Pillow lavas 57, 59, 61Pitch Coppice, Herefordshire

45, 46Plate boundaries 23–5, 23–5,

27Plate tectonics 22–6, 23–4, 28,

57Playfair, John 38Plesiosaurs 32, 34, 40, 48Pollen records 9, 35, 37, 37,

72, 75Precambrian 17, 18, 25–6, 26,

51, 57, 70, 93Prehistoric humans 3, 9, 35,

64Proterozoic Eon 17, 18Proto-Atlantic Ocean 22Pterosaurs 32, 34, 48

QQuarry conservation 30, 32, 39,

47, 49, 56, 60, 62, 64, 84,86, 89–94, 90, 92–3

Quarrying 66, 80, 84, 89, 92,95

Quaternary GCR blocks 50–1,72

Quaternary GCR networks63–6, 64, 65, 75

Quaternary landforms 10, 15,34–7, 35, 49, 51, 65–9, 68,72, 75, 78, 88, 104

Quaternary Period 18, 18,34–7, 51, 63, 72, 78, 83

RRaised beaches 14, 15, 35, 41,

67–9Ramsay, Andrew 41Regionally Important Geolo-

gical/GeomorphologicalSites (RIGS) 76, 85–6,86, 89, 103–4

Reptiles, prehistoric 3, 14, 28,30, 31, 32, 34, 40–1, 47,

Index

130

48, 51, 71, 76, 77, 79Rhynie Chert 7, 28, 47, 49, 50,

99River Dee 97–8, 97River gravels 64–6, 64, 91River processes 37, 51, 97–8Road cutting conservation

96–7, 96Rum 34

S Salisbury Crags, Edinburgh 13,

13San Andreas Fault, California

24Sand dunes 3, 31, 37, 54, 66–9,

68, 88, 105Scar Close National Nature

Reserve, North Yorkshire10

Scottish Natural Heritage 45–6,85, 89, 103–5

Sea lochs 66, 69Sea-level changes 14, 15, 34–5,

41, 49, 53, 54, 66, 68, 72Sedgwick, Adam 39–40, 39Sedimentary rocks 13, 15, 17,

25–6, 41Seven Sisters, Kent 33Shap Granite Quarry, Cumbria

91–2, 91–2Shetland 67, 69Shingle beach ridges 14, 15,

67–9Shingle spits 67, 69Shore-platforms 14, 66, 69Siccar Point, Berwickshire 38,

47Sills 13, 13, 17, 57, 59Silurian Period 7, 16, 18, 18,

26–8, 38, 39–40, 46–7,61–2, 70–1, 87, 87

Silver Howe, Lake District 29Site excavation 90, 96, 97, 99Sites of Special Scientific

Interest 39, 45–6, 48,76–9, 76, 78, 85, 92,98–9, 98, 103–4

legal protection 45–6, 85GCR sites within 79, 79

Skye 33, 34

Skye Main Lava Series 33Smith, William 38Snowdonia, Wales 35Society for the Protection of

Nature Reserves 84Soils 8–9, 61, 67, 104–5South Stack, Anglesey 26South-west England, 39,

57–61, 58–9, 70–2GCR Block 57–61, 58, 70–2granites 28, 57–60, 58–9igneous activity 51, 57–61,

57–9, 71Variscan Orogeny 58–9, 70

Southern Uplands Fault 21, 71Specimen curation 90–1, 97Stonesfield, Cotswolds 47, 48Storm beaches 49Stratigraphic column 17, 18,

18Stratigraphy GCR blocks 50–1,

69–70Stratigraphy 18, 18, 36, 38, 47,

50–1, 66, 69, 72, 79Stratotypes 89

Barton Cliffs 14, 14, 91Corton Cliff 83Dob’s Linn 7Pitch Coppice 45, 46Wenlock Edge 47

Structural and metamorphicgeology GCR blocks50–1, 70

Sully Island, South Wales 31Swanscombe, Kent 35, 64

T Tertiary Period 18, 18, 20, 22,

27, 34, 51, 57, 66, 69, 71,79, 91

Thames Valley 64, 65–6, 65, 72The Storr, Skye 33Till, see boulder clay Torquay, Devon 35, 39Torridonian sediments 26, 51,

70Town and Country Planning

Act, 1990 85, 87Town and Country Planning

(Scotland) Act, 1990 87Traeth Mawr, Brecon Beacons

9Triassic Period 18, 18, 20, 25,

27, 31, 31, 34, 70–1, 96Trilobites 26, 39, 51, 87

U Unconformities 25, 31, 38, 47

V Variscan Orogeny 22, 22, 25,

28, 31, 51, 53, 58–9, 70Volcanic activity 3, 13, 13,

22–5, 25, 28, 30, 34, 48,57–61, 57

Volcanic rocks 13, 17, 17, 26,29, 48, 57–61, 57, 71

Volcanic vents 3, 13

W Waste disposal sites 45, 83, 87,

94, 94, 104Wealden Anticline 20, 22Weathering 3, 3, 15, 35, 37, 80,

97–9Welsh Borders 18, 26, 62Wenlock Edge, Shropshire 47West Runton, Norfolk 35, 37Wildlife conservation 84–7,

103Wildlife Conservation Special

Committee (England andWales) 84

Wildlife and Countryside Act,1981 45, 77, 85, 87

Wren’s Nest National NatureReserve, Dudley 86, 87

Writhlington Rock Store SSSI98, 98

YYorkshire Province network

52, 53–6

Z Zechstein Sea 52, 53, 54, 56

Index

131

G E O L O G I C A L C O N S E RVA T I O NR E V I E W S E R I E S

An Introduction to the Geological Conservation Review

The purpose of this book is to explain the significance of Britain’s Earth heritage — ourinheritance of rocks, soils and landforms — and how the national series of Earth heritagesites was identified in the Geological Conservation Review. It also describes how thesesites are protected by law and explains the practical considerations involved in theirconservation.

This volume is intended primarily for all those with an interest in managing the land:owners and occupiers, managers, planners and those involved in the waste disposal,mineral extraction, construction and coastal engineering industries. It will also be ofinterest to professional and amateur Earth scientists, conservationists, and teachers,lecturers and students of the Earth sciences.

Geological Conservation Review Series 1

The aim of the Geological Conservation Review Series is to provide a public record ofthe features of interest an importance at localities already notified, or being considered fornotification, as ‘Sites of Special Scientific Interest’ (SSSIs). All 42 volumes in the series arewritten to the highest scientific standards and incorporate the cumulative insights ofgenerations of leading Earth scientists, in such a way that the assessment and conservationvalue of the sites is clear. This volume is the introduction to the Series.

The geology of south-west England gives rise to some of Britain’s most spectacular landscape andrich mineral resources, ranging from tin to china clay and building stones. The scientific studyof the rocks in this region has yielded greater understanding of how northern Europe underwenta period of mountain building some 300 million years ago. These immense earth movementswere accompanied by the emplacement into the existing country rocks of vast bodies of moltenigneous rock which cooled to form granite. The photograph shows Haytor Rocks, Dartmoor, anexcellent area in which to examine the textural and compositional variations in the main suiteof Dartmoor granites. This is the reason for the selection of the site as a Geological ConservationReview site. The Dartmoor granite is also renowned for dramatic tor scenery and Haytor iswidely visited as a classic example of such a landscape. Photograph by: S. Campbell

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Geological Conservation Review

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JOINT NATURE CONSERVATION COMMITTEE ISBN 1 86107 403 4Peterborough

Documents

An Introduction conservation. to the Geological