Late Quaternary Environmental Change in North-west Europe: Excavations at Holywell Coombe, South-east England

438 Pages·1998·47.182 MB·English

by  Dr R. C. Preece, Dr D. R. Bridgland (auth.)

Late Quaternary
Environmental Change
in North-west Europe:
Excavations at
Holywell Coombe,
South-east England
R.e. Preece
and
D.R. Bridgland
mJ
CHAPMAN & HALL
Published by Chapman & Hall, 2-6 Boundary Row, London SEt 8HN, UK
First edition 1998
© 1998 Chapman and Hall
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Late Quaternary
Environmental Change
in North-west Europe:
Excavations at Holywell
Coombe, South-east
England
Aerial view of Holywell Coombe and the Folkestone-Etchinghill escarpment, looking westwards. Summer 1990.
Construction of the cut-and-cover tunnel is well underway.
The cover illustration shows exposure of Late-glacial slope deposits overlain by early Holocene organic sediments and
tufa, Holywell Coombe, 1988 (Trench 6). In the background is Castle Hill through which the tunnel is being driven.
Contents
list of contributors xi
Preface xlli
English abstract xv
French abstract xviii
Acknowledgements xxi
Part One. Introduction R. C. Preece 1
(1) Previous work 3
(2) Scientific importance of the Holywell Coombe site 4
(3) Nature of the threat 5
(4) Programme of research 7
(5) The nature of the investigation 8
(6) Nomenclature and terminology 11
(7) Storage and archive 13
Part Two. Environmental Background R.C. Preece and D.R. Bridgland 15
(1) Location of the site 17
(2) Palaeogeographical context 17
(3) Solid geology 20
(4) Geomorphology 21
(a) Regional context 21
Cb) Local context 24
(5) Climate 26
Part Three. The Geology 31
1. Stratigraphical investigations R.C. Preece, n.R. Bridgland and MJ Sharp 33
(1) General stratigraphy inferred from the borehole survey 33
(2) Representative sections 42
(a) Main Section 45
Cb) Trench HV 51
(c) Trench 3 52
(d) Trench 4 54
(e) Trench 5 56
v
Contents
(f) Trench 6 58
(g) Cut-&-cover Section 61
(h) Section below Sugarloaf Hill (BS) 64
(i) Cherry Garden 65
(3) Correlation of sections 68
2. Sedimentological investigations 69
(1) Petrography of sediments and buried soilsJA. Catt and Sj. Staines 69
(a) Introduction 69
(b) Samples analysed 70
(c) Methods 70
(d) Results: particle size distribution, mineralogy and sediment provenance 70
(e) Results: micromorphology and soil development processes 76
(f) Discussion and conclusions 83
(2) Petrology of tufa sediments HM. Pedley 85
(a) General comments 85
(b) Fabric analyses 85
(c) Depositional environments 86
(3) Mineral magnetic properties of valley-fill sediments: implications for
provenance and weathering history Mj. Sharp and JA. Dowdeswell 86
(a) Introduction 86
(b) The sediment infill of Holywell Coombe 89
(c) Sampling and measurement procedures 89
(d) Results: mineral magnetic assemblages 90
(e) Results: stratigraphical analyses 101
(f) Discussion 105
Part Four. Radiocarbon Dating v'R. Switsur and R.A. Housley 107
(1) Introduction 109
(2) Physical and chemical pretreatment 109
(a) Cambridge 110
(b) Oxford 110
(3) Sample preparation and isotopic measurement 111
(a) Conventional measurement in Cambridge 111
(b) AMS measurement in Oxford 111
(4) Results and discussion 112
(a) Radiocarbon dating of colluvial sediments 112
(b) Radiocarbon dating of the shells of land snails 112
(c) Comparison of radiocarbon ages from shell carbonate
and organic materials 114
(d) Radiocarbon dating of the 'Allen~d soil' 115
(e) Possible calibration of Late-glacial radiocarbon ages 115
(f) Radiocarbon plateaux 117
(g) Late-glaciallPost-glacial boundary 118
(h) Conclusions 118
Part Five. Biostratigraphy and Palaeoecology 121
1. Palaeobotany K.D. Bennett and R.C Preece 123
(1) Introduction 123
(2) Methods and results 123
(a) Pollen (analysed by S.M Peglar) 123
vi
Contents
(b) Macrofossils (analysed by M.E. Pettit) 130
(c) Wood and charcoal (analysed by R. Gale) 130
(d) Mosses (analysed by C.R. Stevenson) 130
(3) Vegetational history 133
(4) Notable plant records 142
(5) Discussion 143
(a) Taphonomy and preservation 143
(b) Comparison with other sequences in south-east England 143
(c) Timing of the arrival of trees in Britain in the early Post-glacial 146
(d) Nature of eady Post-glacial vegetation on chalk 147
(6) Conclusions 148
2. Fungal spores and other microfossils JJ. Blackford 149
(1) Introduction: Quaternary palaeomycology 149
(2) Methods: preparation and enumeration 150
(3) Results 150
(4) Fungi, algae and other non-pollen microfossils 150
(a) Identified fungi of known or partly-known affinities 150
(b) Unidentified fungal remains with previously recorded distributions 152
(c) Unidentified fungal remains not previously recorded 153
(d) Microfossils other than fungal remains 154
(5) Sample interpretations 155
(6) Conclusions 156
(a) Comparison with Usselo 156
(b) Summary 156
3. Mollusca R.C Preece 158
(1) Introduction 158
(2) Sampling and laboratory analysis 159
(3) Preservation 169
(4) Notes on identification 169
(5) Analysis of faunal change through the sections 181
(a) Main Section: Deep Trench 1 and Sump 3 (series 1) 181
(b) Main Section: Deep Trench 2 (series 2) 184
(c) Trench HV 187
(d) Trench 3 190
(e) Trench 4 192
(f) Trench 5 192
(g) Trench 6 193
(h) Cut-&-cover Section 193
(i) Section below Sugarloaf Hill (BS) 193
(j) Cherry Garden 196
(6) Notes on selected species 199
(7) Reversed coiling 204
(8) Traces of predation 204
(9) Synthesis of faunal history and molluscan zonation 204
(10) Discussion and conclusions 208
4. Insects G.R. Coope 213
(1) Introduction 213
vii
Contents
(2) Sampling and analysis 213
(3) Local environmental reconstructions based on the Coleoptera 219
(4) Analysis of faunal changes 219
(a) Zone 1 219
(b) Zone 2 221
(c) Zone 3 223
(d) Zone 4 224
(5) Summary of the local environment inferred from the Coleoptera 229
(6) Climatic implications of the Coleoptera 229
(7) Caddisflies and other aquatic insects NB. Williams 232
(8) Chironomidae 233
5. Mites J. Schelvis 234
(1) Introduction 234
(2) Material and methods 235
(3) Results 235
(a) Section BS, sample A 237
(b) Section BS, sample B 238
(c) Section BS, sample C 238
(4) Discussion 240
(5) Conclusions 241
6. Ostracoda J.E. Robinson 242
(1) Introduction 242
(2) Sampling and treatment of data 242
(3) Taxonomy and problems of identification 245
(4) Faunal analyses of the profiles 245
(a) Trench HV 245
(b) Trench 3 247
(c) Trench 4 248
(d) Trench 5 248
(e) Trench 6 250
(5) Comments on species of interest 250
(6) Discussion and conclusions 252
7. Vertebrates A.M. Lister and AJ. Stuart 254
(1) Introduction 254
(2) Identification and interpretation 254
(a) Late-glacial 254
(b) Early Post-glacial 256
(c) Bronze Age and Iron Age 257
Part Six. The Prehistory of Holywell Coombe P. Bennett, S. Ouditt 261
andJ Rady with contributions from A. Gibson, B. Healey and
N Macpherson-Grant
(1) Introduction 263
(a) Previous finds 263
(b) Methodology 263
(c) Summary of results 263
(2) The 1987 excavation 264
viii
Contents
(a) The general stratigraphic sequence 264
(b) The early settlement features 265
(c) Basal buried soil and Late Bronze Age-Early Iron Age features 270
(d) The Early Iron Age soil horizon 272
(e) The later sequence of hillwash 273
(f) Summary 273
(3) The 1988 excavation 284
(a) Introduction 284
(b) Late Neolithic-Bronze Age transition (ca. 2500-1850 Be) 284
(c) Later Bronze Age (ca. 1300-600 Be) 289
(d) Early Iron Age (ca. 600-400 Be) 290
(e) Middle or Late Iron Age (ca. 300-75 Be) to Post-medieval 290
(f) Summary 290
(4) The flint-work E. Healey 291
(a) Chronology and implications 291
(b) Traditions and illustrated material 292
(c) Industries, condition and raw material 293
(d) Technological aspects 293
(5) The Neolithic-Early Bronze Age pottery A. Gibson 295
(a) Chronology and implications 295
(b) Traditions and illustrated material 297
(c) Fabric groups and technological aspects 299
(6) The Late Bronze Age and Iron Age pottery N Macpherson-Grant 302
(a) Chronology and implications 302
(b) Traditions and illustrated material 303
(c) Fabric groups and technological aspects 305
C) The 'Belgic', Roman and later pottery N Macpherson-Grant 308
(a) Chronology and implications 308
(b) Traditions and illustrated material 309
(c) Fabric groups 310
(8) Conclusions 311
(9) Holywell Coombe and other Channel Tunnel sites: a brief overview 312
Part Seven. Present-day Ecology of the Folkestone Escarpment 315
R.C. Welch
(1) Introduction 317
(2) Modem surface soils fA. Catt 317
(a) Introduction 317
(b) Effects of bedrock geology 318
(c) Effects of Quaternary deposits 318
(d) Descriptions of soil series in the immediate area 319
(3) Vegetation 322
(a) Escarpment grassland 322
(b) Escarpment woodland and scrub 327
(c) Holywell Coombe fen and scrub communities 328
(d) Plants of marsh, fen and stream 331
(4) Invertebrate fauna 333
(a) Terrestrial invertebrates 333
(b) Aquatic invertebrates 350
(5) Discussion and conclusions 357
ix
Contents
Part Eight. Synthesis R. C Preece 359
(1) Geological sequence at Holywell Coombe 361
(a) 'B011ing' and earlier 361
(b) 'Aller0d' 363
(c) Younger Dryas (Loch Lomond Stadial) 366
(d) The early to mid Post-glacial 367
(e) The late Post-glacial 370
(2) General conclusions and comparisons with sites elsewhere 372
(a) The Late-glacial period 372
(b) The Post-glacial period 379
References 383
Index 405
x