Fluvial Geomorphology of Great Britain

TH E GEOLOGICA L CONSERVATIO N REVIE W SERIE S

The comparatively small land area of Great Britain contains an unrivalled sequence of rocks, mineral and fossil deposits, and a variety of landforms which encompass much of the Earth's long history. Well-documented ancient volcanic episodes, famous fossil sites, and sedimentary rock sections, used internationally as comparative standards, have given these islands an importance out of all proportion to their size. The long sequences of strata and their organic and inorganic contents have been studied by generations of lead-ing geologists, giving Britain a unique status in the development of the science. Many of the divisions of geological time used throughout the world are named after British sites or areas; for instance the Cambrian, Ordovician and Devonian systems, the Ludlow Series and the Kimmeridgian and Portlandian stages.

The Geological Conservation Review (GCR) was initiated by the Nature Conservancy Council in 1977 to assess and document the most scientifically-important parts of this rich heritage. The GCR reviews the current state of knowledge of key earth-science sites in Britain and provides a firm basis upon which site conservation can be founded in years to come. Each GCR volume describes and assesses networks of sites of national or interna-tional importance in the context of a portion of the geological column, or a geological, palaeontological, or mineralogical topic. The full series of 42 volumes wil l be published by the year 2000.

Within each individual volume, every GCR locality is described in detail in a self-con-tained account, consisting of highlights (a precis of the special interest of the site), an introduction (with a concise history of previous work), a description, an interpretation (assessing the fundamentals of the site's scientific interest and importance), and a conclu-sion (written in simpler terms for the non-specialist). Each site report is a justification of a particular scientific interest at a locality, of its importance in a British or international set-ting, and ultimately of its worthiness for conservation.

The aim of the Geological Conservation Review series is to provide a public record of the features of interest in sites being considered for notification as Sites of Special Scientific Interest (SSSIs). It is written to the highest scientific standards but in such a way that the assessment and conservation value of the sites is clear. It is a public statement of the value placed upon our geological and geomorphological heritage by the earth-science community that has participated in its production, and it wil l be used by the Joint Nature Conservation Committee, the Countryside Council for Wales, English Nature and Scottish Natural Heritage in carrying out their conservation functions. The three country agencies are also active in helping to establish sites of local and regional importance. Regionally Important Geological/Geomorphological Sites (RIGS) augment the SSSI coverage, with local groups identifying and conserving sites which have educational, historical, research or aesthetic value, enhancing the wider earth-science conservation perspective.

Al l the sites in this volume have been proposed for notification as SSSI; the final deci-sion to notify or re-notify sites lies with the governing councils of the appropriate country conservation agency.

Information about the GCR publication programme may be obtained from:

GCR Unit, Joint Nature Conservation Committee, Monkstone House, City Road, Peterborough, PE1 1JY.

Title s i n th e serie s

1. An Introductio n to the Geological Conservation Review N.V. Ellis, (ed.), D.Q. Bowen, S. Campbell, J.L. Knill , A.P. McKirdy , CD. Prosser, M.A. Vincent and R.C.L. Wilson

2. Quaternary of Wales S. Campbell and D.Q. Bowen

3. Caledonian Structures in Britai n South of the Midland Valley Edited by J.E. Treagus

4. British Tertiar y Volcanic Province C. H. Emeleus and M.C. Gyopari

5. Igneous Rocks of South-west England P.A. Floyd, C.S. Exley and M.T. Styles

6. Quaternary of Scotland Edited by J.E. Gordon and D.G. Sutherland

7. Quaternary of the Thames D. R. Bridgland

8. Marin e Permian of England D.B. Smith

9. Palaeozoic Paleobotany of Great Britai n C J. Cleal and B.A. Thomas

10. Fossil Reptiles of Great Britai n M.J. Benton and P.S. Spencer

11. British Upper Carboniferous Stratigraphy C J. Cleal and B.A. Thomas

12. Karst and Caves of Great Britai n A.C. Waltham, M J. Simms, A.R. Farrant and H.S. Goldie

13 • Fluvial Geomorphology of Great Britai n Edited by K.J. Gregory

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Fluvial Geomorphology of Great Britain

Edite d b y

K.J . Gregor y Goldsmith s College , Universit y of London , U K

Section s co-ordinate d b y A . Werritty , J . Lewin , A.M . Harvey , M.G . Mackli n an d K.J . Gregor y

GCR Editor : J.M . Hook e

J O I N T NATUR E CONSERVATION COMMITTE E

SPRINGER-SCIENCE+BUSINES S MEDIA , B . V .

First edition 1997

© 1997 Springer Science+Business Media Dordrecht

Originally published by ]oint Nature Conservation Committee in 1997 Softcover reprint ofthe hardcover Ist edition 1997

Typeset in 10/12pt Garamond ITC by Columns Design Ltd, Reading, Berkshire

ISBN 978-94-010-6456-9 ISBN 978-94-011-5816-9 (eBook)

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The publisher makes no representation, express or implied, with regard to the accuracy of the inforrnation contained in this book and cannot accept any legal responsibility or liability for any errors or omissions that may be made.

British Geologica1 Survey Copyright protected materials

1. The copyright of materlals derived from the British Geological Survey's work is vested in the Natural Environment Research Council [NERC]. No part of these materlals (geological maps, charts, plans, diagrams, graphs, cross-sections, figures, sketch maps, tables, photographs) may be reproduced or transmitted in any form or by any means, or stored in a retrieval system of any nature, without the written permission of the copyright holder, in advance.

2. To ensure that copyright infringements do not arise, permission, has to be obtained from the copyright owner. In the case of BGS maps this includes both BGS and Ordnance Survey. Most BGS geological maps make use of Ordnance Survey topography (Crown Copyright), and this is acknowledged on BGS maps. Reproduction of Ordnance Survey materlals may be independently permitted by the licences issued by Ordnance Survey to many users. Users who do not have an Ordnance Survey licence to reproduce the topography must make their own arrangments with the Ordnance Survey, Copyright Branch, Romsey Road, Southampton, S09 4DH (Tel. 01703 792913).

3. Permission to reproduce BGS materlals must be sought in writing from Dr ]ean Alexander, Copyright Manager, British Geological Survey, Kingsley Dunham Centre, Keyworth, Nottingham, Notts. NG12 5GG (Tel. 01159363331).

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

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(9 Printed on acid-free text paper, manufactured in accordance with ANSI/NISO Z39.48-1992 (permanence of Paper).

DOI 10.1007/978-94-011-5816-9

Contents

1he authors x Acknowledgements xi Access to the countryside xiii Preface xv

1 An introduction to the fluvial geomorphology of Britain KJ. Gregory 1

Introduction 3 River processes 4 The history of fluvial processes 7 Fluvial landscapes and pressures 9 Conclusion 12

2 Fluvial geomorphology of Scotland 19

Fluvial landforms and processes in ScotlandA. Werritty and LJ. McEwen 21 Corrieshalloch Gorge, Highland LJ. McEwen 32 Falls of Clyde, South Lanarkshire A. Werritty and LJ. McEwen 33 River Findhom at Randolph's Leap, Moray LJ. McEwen and A. Werritty 35 Falls of Dochart, Stirling LJ. McEwen and A. Werritty 37 The Grey Mare's Tail, Borders LJ. McEwen and A. Werritty 39 River Clyde meanders, South Lanarkshire A. Werritty and LJ. McEwen 40 Strathglass meanders, Highland LJ. McEwen 44 Abhainn an t-Srath Chuileannaich, Highland LJ McEwen 46 Endrick Water, Stirling LJ. McEwen and A. Werritty 48 Derry Bum, Aberdeenshire LJ. McEwen 52 River Balvag delta, Stirling LJ. McEwen 53 The Lower River Spey, Moray LJ. McEwen 56 Glen Feshie, HighlandA. Werritty and LJ. McEwen 58 The Allt Dubhaig, Perthshire and Kinross A. Werritty 66 Dorback Bum, HighlandA. Werritty 69 Glen Coe: river and slope forms, Highland LJ. McEwen 72 Luibeg Bum, Aberdeenshire LJ. McEwen 76 Allt Mor (River Nairn), Highland LJ. McEwen and A. Werritty 78 Allt Coire Gabhail, Highland A. Werritty 81 Allt Mor (River Druie), Highland LJ. McEwen and A. Werritty 83 Quoich Water alluvial fan, Aberdeenshire LJ. McEwen 87 Allt a' Choire, Highland A. Werritty and AM. Harvey 89

vii

Contents

Allt Coire Chailein fan, Argyll and Bute LJ. McEwen and A. Werritty 92 Eas na Broige debris cone, Highland A. Werritty and Lj. McEwen 95 Oldhamstocks Bum, East Lothian A. Werritty and LJ. McEwen 97 Findhorn Terraces, Highland LJ. McEwen and A. Werritty 99 North Esk and West Water palaeochannels, Angusj.E. Gordon,

LJ. McEwen and A. Werritty 101 Glen Roy, Glen Spean and Glen Gloy, Highlandj.E. Gordon and

LJ. McEwen 104

3 Fluvial geomorphology of Wales 115

Fluvial landforms and processes in Wales j. Lewin 117 Mon Ilugwy between Swallow Falls and Betws-y-Coed, Aberconwy

and Colwyn G. Higgs 119 Mon Rhaeadr at Pistyll Rhaeadr, Powys G. Higgs 121 Mon Cynfal at Rhaeadr y Cwm and Rhaeadr Cynfal, Caernarfonshire and

Merionethshire G. Higgs 123 Mon Twymyn at Ffrwd Fawr, Powys G. Higgs 125 Mon Glaslyn at Aberglaslyn, Caemarfonshire and Merionethshire G. Higgs 127 Mon Teifi at Cenarth, Carmarthenshire G. Higgs 129 River Dee at llangollen, Denbighshire G. Higgs 132 River Wye at Lancaut, Monmouthshire G. Higgs 134 Mon Hepste, Powys G. Higgs 135 Mon Mellte downstream ofYstradfellte, Powys G. Higgs 137 Mon Dyfi between Dinas Mawddwy and Mallwyd, Caernarfonshire and

Merionethshire G. Higgs 141 Mon Rheidol, Cardiganshire j. Lewin 143 Mon Vymwy, Powysj. Lewin 146 Mon Ystwyth, Cardiganshire G. Higgs 148 Upper Elan upstream of Craig Goch Reservoir at Bodtalog, Powys G. Higgs 150 Upper River Severn between Dolwen and Penstrowed, Powys R.D. Hey 152 River Severn between Welshpool and the confluence of the Vymwy and

Severn, Powys G. Higgs 157 River Dee, Holt to Worthenbury A.M Gurnell 159 Mon Teifi at Cors Caron, Cardiganshire G. Higgs 163 Maesnant, Pumlumon (plynlimon), Ceredigionj.A.A.jones 165 Black Mountain scarp, Ceredigion G. Higgs 167

4 Fluvial geomorphology of north-west England AM. Harvey 173

Holocene fluvial development in north-west England 175 Geology, relief and hydrology 177 Fluvial landforms and processes in north-west England 177 Fluvial geomorphology GCR sites in north-west England 178 Langstrathdale, Cumbria 180 Wasdale, Cumbria 182 Fan deltas at Buttermere and Crummock Water, Cumbria 184 Carlingill Valley, Howgill Fells, Cumbria 186 Langdale and Bowderdale Valleys, Howgill Fells, Cumbria 190 Langden Brook, Bowland Fells, Lancashire 194 River Dane, near Swettenham, Cheshire 197

viii

Contents

5 Fluvial geomorphology of north-east England M.G. Macklin

Holocene fluvial development in north-east England Black Burn, Cumbria Garrigill, River South Tyne, Cumbria River Nent, Blagill, Cumbria The Islands (Alston Shingles), River South Tyne, Cumbria Blackett Bridge, River West Allen, Northumberland River Tyne at Low Prudoe, Northumberland Harthope Burn, Northumberland Shaw Beck Gill, North Yorkshire Additional sites in north-east England

Lambley, River South Tyne Thinhope Burn Farnley Haughs, River Tyne

6 Fluvial geomorphology of central and southern England KJ. Gregory with contributions from RJ. Davis

Fluvial landforms and processes in central and southern England GCR site selection Beckford, Hereford and Worcester River Severn at Montford, Shropshire River Axe at Axminster and Whitford, Devon River Exe at Brampford Speke, Devon River Ter at Lyons Hall, Essex River Derwent at Hathersage, Derbyshire Highland Water, Hampshire River Lyn, Devon River Itchen near Knightcote, Warwickshire River Cherwell at Trafford House, Northamptonshire Ashmoor Common, Hereford and Worcester River Severn, Buildwas, Shropshire Alport Valley, Derbyshire Bleaklow, Derbyshire Lydford Gorge, Devon Mimmshall Brook at Water End, Hertfordshire Aysgarth, North Yorkshire Dovedale, North Yorshire River Culm at Rewe, Devon River Lugg, Hereford and Worcester Wilden, Hereford and Worcester

References Glossary Index

ix

201

203 205 209 210 214 217 219 225 227 229 229 231 236

239

241 243 244 247 250 252 255 256 260 265 269 271 273 277 279 281 285 288 290 292 296 299 304

307 333 337

The authors

Professor Ken Gregory is Warden of Goldsmiths College, University of London and Professor of Geography, University of London.

Professor Alan Werritty is Professor of Geography, University of Dundee. Professor John Lewin is Professor of Geography, Institute of Earth Studies, University of

Wales, Aberystwyth. Dr Mark Macklin is Reader in Geography, University of Leeds. Dr Adrian Harvey is Reader in Geography, University of Liverpool.

Other contributors

Richard Davis is a Hydrologist with the Environment Agency. Professor Angela Gurnell is Professor of Geography, University of Birmingham. Dr Gary Higgs is Lecturer in GIS, Department of City and Regional Planning, University

of Wales, Cardiff. Dr Richard Hey is Reader in Environmental Sciences, University of East Anglia. Dr Lindsey McEwen is Lecturer in Geography, Cheltenham and Gloucester College of

Higher Education. Dr Tony Jones is Reader in Geography, Institute of Earth Studies, University of Wales,

Aberystwyth. Dr John Gordon is Quaternary Geomorphologist, Scottish National Heritage, Edinburgh. Professor Janet Hooke is Professor of Physical Geography, University of Portsmouth.

x

Acknowledge1nents

Work on the identification of fluvial geomorphology sites for the Geological Conservation Review (GCR) was started by the Nature Conservancy Council (NCC) in 1985 with a widespread consultation exercise coordinated by John Gordon (now of Scottish Natural Heritage). The task of site selection and data compilation had been largely completed before the Nature Conservancy Council was reorganized into three country-based conservation agencies and their Joint Nature Conservation Committee ONCC) in 1991.

The task of selecting and documenting the results of the fluvial geomorphology site review necessarily took a number of years; it was a complex project which was fur­ther complicated by the senior author and two of the regional authors moving to new posts during the period of text production. Therefore, the first stage of the data assem­bly and compilation of the recommended list of sites was undertaken at the University of St Andrews for GCR sites in Scotland, at the University of Newcastle-upon-Tyne for north-east England, and at the University of Southampton for southern England, before Alan Werritty moved to Dundee, Mark Macklin to Leeds and Ken Gregory to London. Data for the sites in Wales were compiled at the University of Wales, Aberystwyth, and for north-west England at the University of Liverpool. The necessary research was undertaken for these five separate regions (,Fluvial Geomorphology GCR Blocks') from the five universities mentioned above. During the course of data collection, a consid­erable amount of field work was involved; for the larger areas a research assistant worked with the respective GCR Block coordinator in finalizing the list of sites and in collecting the necessary data. Lindsay McEwen worked in this role with Alan Werritty for Scotland, Gary Higgs with John Lewin for Wales and Huw Rowlands and subse­quently Richard Davis with Ken Gregory for southern England.

Work towards publication of the results of the review was initiated by the NCC, and resumed in 1992 under the auspices of the JNCC on behalf of the three statutory nature country agencies, the Countryside Council for Wales, English Nature and Scottish Natural Heritage.

As evidenced by the text for each site, major reliance is placed necessarily on the work of many individuals, and particularly on the contributions made by members of the British Geomorphological Research Group. For each site, all of the source material is acknowledged as fully as possible and we have endeavoured to provide the most up-to-date summary; we are of course aware that research at the time of publication and also in the future will continue to provide more knowledge and understanding for many of the sites described in this volume. However, during the course of pro­ducing the site descriptions, many individuals have contributed comments and assistance in respect of particular sites. Grateful acknowledgement is therefore made

xi

Acknowledgements

for the contributions made in different ways by Dr Tony Brown, Mr Tim Heap, Dr Richard Hey, Mr Chris Hill, Dr Tony Jones, Professor Malcolm Newson, Dr Dave Passmore, Professor Keith Richards, Mr Huw Rowlands, Dr Barbara Rumsby, Mr Watts Stelling and Professor Des Walling.

We are grateful also to Dr Rob Ferguson, who reviewed a draft of the text and to Professor Janet Hooke, GCR Editor. Both made many useful suggestions about the final content of the volume.

Since 1992, the help of Mr Neil Ellis as GCR Publications Manager, together with other members of the publication production team, including Mr Justin Farthing and Mr Nick Davey, has been very much appreciated. The excellent care and consideration given by Dr Chris Pamplin of XIPRESS helped enormously to produce the diagrams.

To all people who have asSisted, over more than ten years, grateful acknowledge­ment is recorded, particularly to the way in which the authors have collaborated.

xii

Access to the countryside

1bis volume is not intended for use as a field guide. The description or mention of any site should not be taken as an indication that access to a site is open or that a right of way exists. Most sites described are in private ownership, and their inclusion herein is solely for the purpose of justifying their conservation. Their description or appearance on a map in this work should in no way be construed as an invitation to visit. Prior consent for visits should always be obtained from the landowner and/or occupier.

Information on conservation matters, including site ownership, relating to Sites of Special Scientific Interest (SSSIs) or National Nature Reserves (NNRs) in particular coun­ties or districts may be obtained from the relevant country conservation agency headquarters listed below:

English Nature, Northminster House, Peterborough PEl 1 UA.

Scottish Natural Heritage, 12 Hope Terrace, Edinburgh EH9 2AS.

Countryside Council for Wales, Plas Penrhos, Ffordd Penrhos, Bangor, Gwynedd llS7 2LQ.

xiii

Preface

lbis book summarizes the results of part of the Geological Conservation Review (GCR), an extensive research programme that aimed to assess the scientific significance of Britain's geological and geomorphological localities so that the most important ones could be protected by law. Ultimately, the GCR sites were selected with a view to their designation as Sites of Special Scientific Interest (SSSIs).

In this volume the scientific importance of the set of fluvial geomorphology GCR sites is described.

The surveys of fluvial geomorphology sites were carried out initially for five areas of the country (Le. for five fluvial geomorphology GCR 'Blocks'), reflected in chapters 2 - 6 of this volume. In each block, a list of candidate GCR sites was established on the basis of previous research and published material; after consultation with as many peo­ple as possible and visits to as many sites as possible, the list was refined to contain only the most scientifically important localities. The comments made, and advice received, from a large number of experts became a significant element in the finaliza­tion of the list of GCR sites which were needed to reflect the diversity of the fluvial geomorphology of Britain, and the history of research and investigation already under­taken. When finalizing the list of GCR sites, the criteria of minimum duplication of special scientific interest between sites within an overall framework of selecting the most representative, exceptional, unique and internationally important GCR sites were kept clearly in mind.

Because much of the landscape of Britain owes a great deal to rain and rivers, there is potentially a great wealth of sites from which to choose; inevitably we have had to rely on those that have already been discovered, documented and researched. Also, while some of the sites described have been the subject of research or study very recently, others have been known for as long as 100 years, and there may be other clas­sic sites emerging as a result of research that is under way at the present time. This emphasizes the fact that the GCR sites described in this volume represent what might be thought of as a snapshot of a particular point in time, reflecting the way in which the need for a range of sites of different types is reconciled with the background of the information that has become available. It is also important to remember that some potential fluvial geomorphology sites may overlap with sites described in other vol­umes of the Geological Conservation Review Series, which were selected for the GCR for other special interests such as stratigraphy or Quaternary geology and geomor­phology.

Most of the SSSI proposals made as a result of the Geological Conservation Review have already been translated into site designations by the appropriate country conser­vation agencies (the Countryside Council for Wales, English Nature and Scottish Natural Heritage).

xv

Preface

This volume is not intended as a field guide to fluvial geomorphology sites, nor is it intended to cover the practical problems involved in future site conservation. The pur­pose is to record the scientific justification for conserving particular sites and to demonstrate the character and significance that the sites have against the background of a wider geomorphological context. Each site is documented in a self-contained account, starting with the highlights (appraisal of its special scientific interest) and a general introduction (with a note of investigation and research literature concerning the site). A morphologic description of the various features of the site in order to place them in context is followed by an interpretation of the site and its Significance. A con­clusion is produced to give a clear indication of the characteristics of the site, their present Significance and, where appropriate, any suggestions about future work. Although some of the interpretation sections necessarily use some technical terms, the accounts have been constructed to be accessible to the non-specialist as much as pos­sible; also the glossary at the end of the volume is compiled with this in mind.

Readers will appreciate that this volume is not intended to provide a final 'domes­day' list of protected fluvial geomorphology sites in Britain. The purpose of the volume is not only to ensure that the selected GCR sites are available and documented for future generations, but to acknowledge that, as further research is undertaken, addi­tional knowledge can be added to that contained in this volume. Not only will more be learnt about many of the sites included, but also other potential sites will be identified. However, the range of sites described here should demonstrate the wealth of evidence of and interest in the fluvial geomorphology environment of Britain and, as such, pro­vide a vital ingredient for the scientific and natural heritage of the country.

xvi

Ken Gregory January 1997