Geomorffeg afonol Cymru: Heddiw, ddoe ac yfory

Geomorffeg afonol Cymru: Heddiw, ddoe ac yfory
(The geomorphology of Wales’s rivers: Today, yesterday and tomorrow)

Hywel Meilyr Griffiths

This paper presents a review of the fluvial geomorphology research undertaken on Wales’ rivers. As well as discussing trends seen in these studies, by firstly focussing on the work of geologists of the late nineteenth century, and by progressing through the development of geomorphology as a research field to the present interdisciplinary period, the fields that have received particular attention on Welsh rivers are discussed. These include the evolution of the mega-geomorphology of Wales, innovative process studies, the evolution of alluvial fluvial systems to short- and long-term climatic changes, and the response of Welsh rivers to anthropogenic activity.

This range of studies is a result of the nature of Welsh fluvial systems. Firstly, they display an evolutionary history including glacial periods and rejuvenation. Secondly, contemporary processes have created a wide range of channel types, including bedrock channels, gravel bed rivers, meandering, braided, stable and unstable channels. Thirdly, academic interest and pragmatic concerns regarding river management have led to a large body of work that has, in some cases, led to many reaches on Welsh rivers being classed as international archetypes. Gaps in our knowledge are also discussed. These include the need to increase our understanding of contemporary process and to continue the work done on alluvial response and evolution through using the latest techniques to constrain the chronology of fluvial system development. There is a need to extend the spatial scope of our studies to areas which have not received as much attention in the past such as the bedrock and mixed bedrock-alluvial channels of the north-west and the south Wales valleys.


  	Hywel Meilyr Griffiths, 'Geomorffeg afonol Cymru: Heddiw, ddoe ac yfory'
, Gwerddon, 3, May 2008, 36-70.


    Geomorphology, rivers, Wales.


  1. Arkell, B., Leeks, G. J. L., Newson, M. D., ac Oldfield, F. (1983), ‘Trapping and tracing: some recent observations of supply and transport of coarse sediment from upland Wales’, yn Collins, J. D., a Lewin, J. (goln), Modern and Ancient Fluvial Systems, International Association of Sedimentologists, Special Publication 6 (Llundain, Blackwell), t.107–119.
  2. Asiantaeth yr Amgylchedd, Local Environment Agency Plan Severn Uplands Environmental Overview, 15/10/2007, .
  3. Ballantyne, C. K., a Harris, C. (1994), The Periglaciation of Great Britain (Cambridge, Cambridge University Press), t. 330.
  4. Bathurst, J. C. (1979), ‘Distribution of boundary shear stress in rivers’, yn Rhodes, D. D., a Williams, G. P. (goln), Adjustment of the Fluvial System (Dubuque, Iowa, Kendall/Hunt Publishing Company), t.95–116.
  5. Bathurst, J. C., Thorne, C. R., ac Hey, R. D. (1977), ‘Direct measurement of secondary currents in river bends’, Nature, 269, 504–06.
  6. Bathurst, J. C., Thorne, C. R., a Hey, R. D. (1979), ‘Secondary flows and shear stresses at river bends’, Journal of the Hydraulics Division (American Society of Civil Engineers), HY 10, 1277–95.
  7. Battiau-Queney, Y. (1980), Contribution a l’étude, géomorphologique du Massif Gallois (Paris, Honoré Champion), t.797.
  8. Battiau-Queney, Y. (1984), ‘The pre-glacial evolution of Wales’, Earth Surface Processes and Landforms, 9, 229–52.
  9. Battiau-Queney, Y. (1999), ‘Crustal anisotropy and differential uplift: their role in long-term landform development’, yn Smith, B. J., Whalley, W. B., Warke, P. A. (gol.), Uplift, erosion and stability: Perspectives on long term landscape development, Special Publication 162 (Llundain, Geological Society), t.65–74.
  10. Bell, M. (1982), ‘The effects of land-use and climate on valley sedimentation’, yn Harding, A. F. (gol.), Climatic Change in Later Prehistory (Caeredin, Gwasg Prifysgol Caeredin), t.127–42.
  11. Blacknell, C. (1980), Point Bar Formation in Welsh Rivers (Traethawd doethuriaeth, Prifysgol Cymru Aberystwyth), t.385.
  12. Blacknell, C. (1982), ‘Morphology and surface sedimentary features of point bars in Welsh gravel-bed rivers’, Geological Magazine, 119, 182–92.
  13. Bowen, D. Q. (1967), ‘On the supposed ice-dammed lakes of South Wales’, Transactions of the Cardiff Naturalists’ Society, 93, 4–17.
  14. Bowen, D. Q., a Lear, D. L. (1982), ‘The Quaternary geology of the lower Teifi valley’, yn Bassett, M. G. (gol.), Geological Excursions in Dyfed, SW Wales, (Caerdydd, Amgueddfa Genedlaethol Cymru), t.297–302.
  15. Bowen, D. Q., Rose, J., McCabe, A. M., et al. (1986), ‘Correlation of Quaternary glaciations in England, Ireland, Scotland and Wales’, Quaternary Science Reviews, 5, 299–340.
  16. Brewer, P. A., a Lewin, J. (1993), ‘In-transport modification of alluvial sediment: field evidence and laboratory experiments’, Special Publication of the International Association of Sedimentologists, 17, 23–35.
  17. Brewer, P. A., a Lewin, J. (1998), ‘Planform cyclicity in an unstable reach: complex fluvial response to environmental change’, Earth Surface Processes and Landforms, 23, 989–1008.
  18. Brewer, P. A., a Passmore, D. G. (2002), ‘Sediment budgeting techniques in gravel-bed rivers’, yn Jones, S. J., a Frostick, L. E. (goln), Sediment Flux to Basins: Causes, Controls and Consequences (Llundain, Geological Society Special Publications, 191), t. 97–113.
  19. Brewer, P. A., a Taylor, M. P. (1997), ‘The spatial distribution of heavy metal contaminated sediment across terraced floodplains,’ Catena, 30 (2), 229–49.
  20. Brewer, P. A., Maas, G. S., a Macklin, M. G. (2000), ‘A fifty year history of exposed riverine sediment dynamics on Welsh Rivers’, yn Jones, J. A., Gilman, A. K., Jigorel, A., a Griffin, J. (goln), Water in the Celtic world: managing resources for the 21st century, British 62 Hydrological Society Occasional Paper, 11, t.245–52.
  21. Brewer, M. G., Macklin, P. A., a Jones, A. F. (2002), ‘Channel change and bank erosion on the Afon Rheidol: the Felin Rhiwarthen and Lovesgrove meanders’, yn Macklin, M. G., Brewer P. A., a Coulthard, T. J., (goln), River Systems and Environmental Change in Wales: Field Guide (Aberystwyth, British Geomorphological Research Group), t.24–31.
  22. Brewer, P. A., Coulthard, T. J., Davies, J., et al. (2005), ‘Flooding-related research in Wales – some recent developments’, yn Bassett, M. G., Deisler, V. K., a Nichol, D. (goln), Urban Geology in Wales 2 (Caerdydd, National Museum of Wales Geological Series No.24), t.229–38.
  23. Brewer, P. A., Johnstone, E., a. Macklin, M. G. (1987), ‘River dynamics and Late Quaternary environmental change’, yn Williams, D., a Duigan, C., Rivers of Wales (yn y wasg).
  24. Brookes, A. (1960), ‘River channel adjustments downstream from channelization works in England and Wales’, Earth Surface Processes and Landforms, 12, 337–51.
  25. Brown, E. H. (1960), The Relief and Drainage of Wales (Caerdydd, Gwasg Prifysgol Cymru), t.187.
  26. Brown, A. G. (1983), ‘Floodplain deposits and accelerated sedimentation in the lower Severn basin’, yn Gregory, K. J. (gol.), Background to Palaeohydrology (Chichester, Wiley & Sons), t.375–97.
  27. Brown, A. G. (1983), ‘Long-term sediment storage in the Severn and Wye catchments’, yn Gregory, K. J., Lewin, J., a Thornes, J. B. (goln), Palaeohydrology in Practice (Chichester, Wiley & Sons), t.307–32.
  28. Brown, A. G. (2003), ‘Global environmental change and the palaeohydrology of western Europe: a review’, yn Gregory, K. J., a Benito, G. (goln), Palaeohydrology: Understanding Global Change (Chichester, Wiley & Sons), t.105–21.
  29. Bull, J. (1997), ‘Relative velocities of discharge and sediment waves for the River Severn’, UK Hydrological Sciences Journal, 42, 649–60.
  30. Burrin, P. J., a Scaife, R. G. (1988), ‘Environmental thresholds, catastrophe theory and landscape sensitivity: their relevance to the impact of man on valley alluviations’, yn Bintliff, J. L., Davison, D. A., a Grant, E. G. (goln), Conceptual Issues in Environmental Archaeology (Rhydychen, British Archaeological Report Series 186), t.145–59.
  31. Campbell, S., a Bowen, D. Q. (1989), Quaternary of Wales, Geological Conservation Review Series (Peterborough, Nature Conservancy Council), t.237.
  32. Charlesworth, J. K. (1929), ‘The South Wales end moraine’, Quarterly Journal of the Geological Society of London, 85, 335–58.
  33. Cope, J. C. W. (1994), ‘A latest Cretaceous hotspot and the southeasterly tilt of Britain’, Journal of the Geological Society, 151 (6), 905–08.
  34. Coulthard, T. J., a Macklin, M. G. (2001), ‘How sensitive are river systems to climate and landuse changes? A model-based evaluation’, Journal of Quaternary Science, 16, 347–51.
  35. Coulthard, T. J., a van de Wiel, M. J. (2006), ‘A cellular model of river meandering’, Earth Surface Processes and Landforms, 31, 123–32.
  36. Coulthard, J. T., Lewin, J., a Macklin, M. G. (2005), ‘Modelling differential and complex catchment response to environmental change’, Geomorphology, 69, 224–41.
  37. Darwin, C. R., llythyr at Ramsay, A. C., Hydref 3, 1846.
  38. Davis, W. M. (1912), ‘A geographical pilgrimage from Ireland to Italy’, Annals of the Association of American Geographers, 2, 73–100.
  39. Davies, B. E., a Lewin, J. (1974), ‘Chronosequences in alluvial soils with special reference to historic lead pollution in Cardiganshire, Wales’, Environmental Pollution, 6, 49–57.
  40. Dobson, M. R., a Lewin, J. ‘The Sedimentation of Aberystwyth Harbour’, Adroddiad i Gyngor Dosbarth Ceredigion, heb ei gyhoeddi.
  41. Galay, V. J., Rood, K. M., a Miller, S. (1998), ‘Human interference with braided gravel-bed rivers’, yn Klingeman, P. C., Beschta, R. L., Komar, P. D., a Bradley, J. B. (goln), Gravel-Bed Rivers in the Environment, Water Resources Publication (Colorado, UES), t.471–512.
  42. George, T. N., (1961), ‘The Welsh landscape’, Science Progress, 49, 242–64.
  43. George, T. N. (1974), ‘The Cenozoic evolution of Wales’, yn Owen, T. R. (gol.), The Upper Palaeozoic and post-Palaeozoic Rocks of Wales (Caerdydd, Gwasg Prifysgol Cymru), t.341–71.
  44. Gilman K., a Newson, M. D. (1980), 'Soil pipes and pipe flow – a hydrological study in Upland Wales', British Geomorphological Group Research Monograph, Rhif 1 (Norwich, Geobooks).
  45. Gittins, S. (2004), Changes in sediment storage in Welsh rivers 1890–2002 (Traethawd doethuriaeth, Prifysgol Cymru Aberystwyth), t.351.
  46. Gray, J. M., a Coxon, P. (1991), ‘The Loch Lomond Stadial glaciation in Britain and Ireland’, yn Ehlers, J., Gibbard, P. L., a Rose, J. (goln), Glacial Deposits in Great Britain and Ireland (Rotterdam, A.A. Balkema), t.89–105.
  47. Grimshaw, D. L., a Lewin, J. (1980), ‘Resevoir effects on sediment yield’, Journal of Hydrology 47, 163–71.
  48. Grimshaw, D. L., Lewin, J., a Fuge, R. (1976), ‘Seasonal and short-term variations in the concentration and supply of dissolved zinc to polluted aquatic environments’, Environmental Pollution, 11, 1–7.
  49. Gurnell, A. M. (1997), ‘Channel change on the River Dee meanders, 1946-1992, from the analysis of air photographs’, Regulated: Rivers Research and Management, 13, 13–26.
  50. Gurnell, M. J., Clark, A. M., Hill, C.T., et al. (1993), The River Dee Meanders (Holt to Wothenbury), Adroddiad i Gyngor Cefn Gwlad Cymru gan Sefydliad GeoData (Prifysgol Southampton), t. 69.
  51. Gurnell, A. M., Downward, R. S., Jones, R. (1994), ‘Channel planform change on the River Dee meanders, 1976–1992’, Regulated Rivers, 9, 187–204.
  52. Harland, W. B., Armstrong, R. L., Cox, L. A., et al. (1989), A Geologic 64 Time Scale (Caergrawnt, Gwasg y Brifysgol), t. 263.
  53. Heritage, G. L., a Hetherington, D. (2007), ‘Towards a protocol for laser scanning in fluvial geomorphology’, Earth Surface Processes and Landforms, 32 (1), 66–74.
  54. Hey, R.D. (1980), ‘Final report on channel stability, Craig Goch Joint Committee’ (heb ei gyhoeddi).
  55. Hey, R. D. (1986), ‘River response to inter-basin water transfers: Craig Goch feasibility study’, Journal of Hydrology, 85, 407–21.
  56. Hey, R. D., Lewin, J., Newson, M. D., a Wood, R. (1981), ‘River management and process studies on the River Severn’, yn Elliot T. (gol.), Field Guide to Ancient and Modern Fluvial Systems in Britain and Spain (University of Keele, International Fluvial Sediments Conference), t.6.16–20.
  57. Heyworth, A., Kidson, C., a Wilks, A. P. (1985), ‘Late-glacial and Holocene sediments at Clarach Bay, near Aberystwyth’, Journal of Ecology, 73, 247–300.
  58. Higgs, G. (1987), ‘Environmental change and hydrological response: flooding in the Upper Severn catchment’, yn Gregory, K. J., Lewin, J., a Thornes, J. B. (goln), Palaeohydrology in Practice (Chichester, Wiley & Sons), t. 31–159.
  59. Higgs, G. (1997), ‘Afon Teifi at Cenarth, Carmarthenshire’, yn Gregory, K. J. (gol.), Fluvial Geomorphology of Great Britain (Llundain, Chapman and Hall), t.129–32.
  60. Higgs, G. (1997), ‘Afon Llugwy between Swallow Falls and Betws y Coed, Aberconwy and Colwyn’, yn K. J. Gregory (gol.), Fluvial Geomorphology of Great Britain (Llundain, Chapman and Hall), t.119–21.
  61. Higgs, G. (1997), ‘Afon Twymyn at Ffrwd Fawr, Powys’, yn Gregory, K. J. (gol.), op cit., t.125–7.
  62. Higgs, G. (1997), ‘Afon Ystwyth, Ceredigion’, yn Gregory, K. J., op cit., t.148–150.
  63. Higgs, G. ‘Afon Teifi at Cors Caron’, yn Gregory K. J., op cit., t.163–5.
  64. Higgs, G., a Petts, P. E. (1988), ‘Hydrological changes and river regulation in the UK’, Regulated Rivers: Research and Management, 2, 349–68.
  65. Hosefield, R. T. a Chambers, J. C. (2002), ‘Processes and experiences – experimental archaeology on a river floodplain’, yn Macklin, M. G., Brewer P. A., a Coulthard, T. J. (gol.), River Systems and Environmental Change in Wales: Field Guide (Aberystwyth, British Geomorphological Research Group), t.32–9.
  66. Howe, G. M., a Thomas, J. M. (1963), Welsh landforms and scenery (Llundain, Macmillan).
  67. Jenkins, J. G. (2005), Ar Lan Hen Afon: Golwg ar ddiwydiannau afonydd Cymru (Aberystwyth, Cymdeithas Lyfrau Ceredigion Cyf), t.189.
  68. Johnstone, E. (2004), River response to Late Quaternary environmental change: the Dyfi catchment, mid-Wales (Traethawd doethuriaeth, Prifysgol Cymru Aberystwyth), t.247.
  69. Johnstone, E., Macklin, M. G., a Lewin, J. (2006), ‘The development and application of a database of radiocarbon-dated Holocene fluvial deposits in Great Britain’, Catena, 66 (1-2), 14–23.
  70. Jones, A. F., Brewer, P. A., Johnstone, E., a Macklin, M. G. (2007), ‘High-resolution interpretive geomorphological mapping of river valley environments using airborne LiDAR data’, Earth Surface Processes and Landforms, 32, 1574–92.
  71. Jones, J. A. A. (1971), ‘Soil piping and stream channel initiation’, Water Resources Research, 7, 602–10.
  72. Jones, J. A. A. (1981), 'The Nature of Soil Piping – a Review of Research', British Geomorphological Research Group Research Monograph, Rhif 3 (Norwich, Geo-books).
  73. Jones, J. A. A., a Crane, F. G. (1981), ‘Pipeflow and pipe erosion in the Maesnant experimental catchment’, yn Burt, T. P., a Walling, D. E. (goln), Catchment experiments in fluvial geomorphology : proceedings of a meeting of the International Geographical Union Commission on Field Experiments in Geomorphology, Exeter and Huddersfield, August 16–24, 1981 (Norwich, Geo-books, 1984), t. 593.
  74. Jones, J. A. A. (1987), ‘The effects of soil piping on contributing areas and erosion patterns’, Earth Surface Processes and Landforms, 12, 229–48.
  75. Jones, O. T. (1911), ‘The physical features and Geology of central Wales’, yn Ballinger, J. (gol.), Aberystwyth and District National Union of Teachers Souvenir (Llundain, National Union of Teachers), t. 25.
  76. Jones, O. T. (1931), ‘Some episodes in the geological history of the Bristol Channel region’, Reports of the British Association, 57.
  77. Jones, O. T. (1951), ‘The drainage systems of Wales and the adjacent regions’, Quarterly Journal of the Geological Society, 107, 201–25.
  78. Jones, O. T. (1956), ‘The drainage systems of Wales and the adjacent regions’, Quarterly Journal of the Geological Society, 111, 323–52.
  79. Jones, O. T. (1965), ‘The glacial and post-glacial history of the Lower Teifi valley’, Quarterly Journal of the Geological Society of London, 121, 247–81.
  80. Jones, O.T. (1970), ‘Longitudinal profiles of the upper Towy drainage system’, yn Dury, G.H. (gol.), Rivers and River Terraces (Llundain, Macmillan), t. 73–94.
  81. Jones, R. L., a Keen, D. H. (1993), Pleistocene Environments in the British Isles (Llundain, Chapman and Hall), t. 346.
  82. Kirkby, C., Newson, M. D., a Gilman, K. (1991), Plynlimon research: the first two decades, Institute of Hydrology Report 109, t. 188.
  83. Kondolf, G. M. (1998), ‘Large-scale extraction of alluvial deposits from rivers in California: geomorphic effects and regulatory strategies’, yn Klingeman, P. C., Beschta, R. L., Komar, P. D., a Bradley, J. B. (goln), Gravel-Bed Rivers in the Environment (Colorado, Water Resources Publication), t.455–70.
  84. Lambeck, K. (1995), ‘Late Devensian and Holocene shorelines of the British Isles and North Sea from models of glacio-hydro-isostatic rebound’, Journal of the Geological Society, 152, 437–48.
  85. Lawler, D. M. (1984), Processes of river bank erosion: the River Ilston, South Wales, UK (Traethawd doethuriaeth, Prifysgol Cymru).
  86. Lawler, D. M. (1992), ‘Design and installation of a novel automatic erosion monitoring system’, Earth Surface Processes and Landforms, 17, 455–64.
  87. Leeks, G. J., (1983) ‘Development of field techniques for assessment of river erosion and deposition in mid-Wales’, yn Burt, T. P., a Walling, D. E. (goln), Catchment Experiments in Fluvial Geomorphology (Norwich, Geobooks), t. 299–309.
  88. Leeks, G. J. (1986), Fluvial sediment responses to high water discharge from a regulating reservoir – The Effects of the 5 March 1985 test release from Llyn Clywedog on the upper Severn, Adroddiad i Awdurdod Dŵr Severn-Trent.
  89. Leeks, G. J., Lewin, J. a Newson, M. D. (1988), ‘Channel change, fluvial geomorphology and river engineering: the case study of the Afon Trannon, mid-Wales’, Earth Surface Processes and Landforms, 13, 207–223.
  90. Lear, D.L. (1986), The Quaternary deposits of the lower Teifi valley (Traethawd doethuriaeth, Prifysgol Cymru Aberystwyth).
  91. Lewin, J. (1972), ‘Late-stage meander growth’, Nature Physical Science, 240, 116.
  92. Lewin, J. (1976), ‘Initiation of bedforms and meanders in coarse-grained sediments’, Geological Society of America Bulletin, 87, 281–85.
  93. Lewin, J. (1977), ‘Channel pattern changes’, yn Gregory, K. J. (gol.), River Channel Changes (Chichester, Wiley & Sons), 167–84.
  94. Lewin, J. (1978a), ‘Meander development and floodplain sedimentation: a case study from mid-Wales’, Geological Journal, 13, 25–36.
  95. Lewin, J. (1978b), ‘Floodplain Geomorphology’, Progress in Physical Geography, 2, 408–38.
  96. Lewin, J. (1981), ‘Contemporary erosion and sedimentation’, yn Lewin, J. (gol.), British Rivers (Llundain, George Allen and Unwin).
  97. Lewin, J. (1982), ‘British floodplains’, yn Adlam, B. H., Fenn, C. R, a Morris, L. (goln), Papers in Earth Studies (Norwich, Geo-books).
  98. Lewin, J. (1983), ‘Changes of channel patterns and floodplains’, yn Gregory, K. J., (gol.), Background to Palaeohydrology (Chichester, Wiley & Sons), t. 303–20.
  99. Lewin, J. (1987), ‘Historical channel changes’, yn Gregory, K. J., Lewin, J., Thornes, J. B. (gol.), Palaeohydrology in Practice (Chichester, Wiley & Sons), t.161–75.
  100. Lewin, J. (1989), ‘Floods in Fluvial Geomorphology’, yn Beven, K., a Carling, P. (goln), Floods: Hydrological, Sedimentological and Geomorphological Implications (Chichester, Wiley & Sons), t.265–84.
  101. Lewin, J. (1992), ‘Alluvial sedimentation style and archaeological sites: the lower Vyrnwy, Wales’, yn Needham, S., a Macklin, M. G. (goln), Alluvial Archaeology in Britain (Rhydychen, Oxbow Press), t.103–9.
  102. Lewin, J. (1992b), ‘Floodplain Construction and Erosion’, yn Calow, P., a Petts, G. E. (gol.), The Rivers Handbook: hydrological and ecological principles, I (Rhydychen. Blackwell), t.526.
  103. Lewin, J., (1997), ‘Fluvial Landforms and Processes in Wales,’ yn Gregory, K. J., (gol.), Fluvial 67 Geomorphology of Great Britain (Llundain, Chapman and Hall), t.117-9.
  104. Lewin, J., a Brindle, B. J. (1977), ‘Confined meanders’, yn Gregory, K. J., op cit., 221–33.
  105. Lewin, J. a Hughes D. (1976), ‘Assessing channel changes on Welsh rivers’, Cambria, 3, 1–10.
  106. Lewin, J., a Hughes, D. (1980), ‘Welsh Floodplain Studies II. Application of a Qualitative Inundation Model’, Journal of Hydrology, 46, 35–49.
  107. Lewin, J., a Macklin, M. G. (1987), ‘Metal mining and floodplain sedimentation in Britain’, yn Gardiner, V. (gol.), International Geomorphology 1986, Part 1 (Chichester, Wiley & Sons), t. 1009–27.
  108. Lewin, J., a Macklin, M. G. (2003), ‘Preservation potential for Late Quaternary river alluvium’, Journal of Quaternary Science, 18, 107–20.
  109. Lewin, J., a Manton, M. M. M. (1975), ‘Welsh Floodplain Studies: The nature of floodplain geometry’, Journal of Hydrology, 25, 37–50.
  110. Lewin, J., Hughes, D., a Blacknell, C. (1977), ‘Incidence of river erosion’, Area, 9, 177–81.
  111. Lewin, J., Davies, B. E., a Wolfenden, P. (1977b), ‘Interactions between channel change and historic mining sediments’, yn Gregory, K. J., op cit., t. 355–67.
  112. Lewin, J., Bradley, S. B., Macklin, M. G. (1983), ‘Historical valley alluviation in mid-Wales’, Geological Journal, 18, 331–50.
  113. Lewis, G. W., a Lewin, J. (1983), ‘Alluvial cutoffs in Wales and the Borderlands’, yn Collinson, J. D., a Lewin, J. (goln), Modern and Ancient Fluvial Systems (Special Publication of the International Association of Sedimentologists 6), t.145–54.
  114. Maas, G. S., Brewer, P. A., a Macklin, M. G. (2001), A Geomorphological Reappraisal of the Upper Severn GCR Site, CCW Contract Science Report No. 433, t.30.
  115. Macklin, M. G. (1999), ‘Holocene river environments in prehistoric Britain: human interaction and impact’, Journal of Quaternary Science, 14, 521–30.
  116. Macklin, M. G., a Lewin, J. (1986), ‘Terraced fills of Pleistocene and Holocene age in the Rheidol Valley, Wales’, Journal of Quaternary Science, 1, 21–34.
  117. Macklin, M. G., a Lewin, J. (1993), ‘Holocene river alluviation in Britain’, Zeitschrift für Geomorphologie, Supplement-Band 88, 109–22.
  118. Macklin, M. G., Ridgway, J. D., Passmore, G., a Rumsby, B. T. (1994), 'The use of overbank sediment for geochemical mapping and contamination assessment: results from selected English and Welsh floodplains', Applied Geochemistry, 9, 689–700.
  119. Macklin, M. G., Brewer, P. A., Jones, A. F., Kershaw, J., a Coulthard, T. J. (2002), ‘A geomorphological investigation of the historical and Holocene development of the River Severn valley floor at Buttington, Powys’, yn Macklin, M.G., Brewer, P.A., a Coulthard, T.J. (gol.), River Systems and Environmental Change in Wales: Field Guide (Aberystwyth, British Geomorphological Research Group), t.24–31.
  120. Macklin, M. G., Johnstone, E., a Lewin, J. (2005), ‘Pervasive and long-term forcing of Holocene river instability and flooding in Great Britain by centennial-scale climate change’, The Holocene, 15, 937–43.
  121. Macklin, M. G., Rumsby, B. T., a Heap, T. (1992), ‘Flood alluviation and entrenchment: Holocene valley-floor development and transformation in the British uplands’, Geological Society of America Bulletin, 104, 631–43.
  122. Meigh, J. R. (1987), Transport of bed material in a gravel bed river (Traethawd doethuriaeth, Prifysgol Cymru Aberystwyth).
  123. Milan, D. J., Heritage, G. L., a Hetherington, D. (2007), ‘Application of a 3D laser scanner in the assessment of erosion and deposition volumes and channel change in a proglacial river’, Earth Surface Processes and Landforms, 32, 1657–74.
  124. Millward, R., a Robinson, A. (1978), Aspects of the North Wales Landscape (Newton Abbott, David and Charles).
  125. Mitchell, D. J., a Gerard, A. J. (1983), ‘Morphological responses and sediment patterns’, yn Gregory, K. J., Lewin, J., a Thornes, J. B. (goln), Palaeohydrology in Practice (Chichester, Wiley & Sons), t.177–99.
  126. Mount, N. J., Sambrook Smith, G. H., a Stott, T. (2005), ‘An assessment of the impact of upland afforestation on lowland river reaches: the Afon Trannon, mid-Wales’, Geomorpholgy, 64 (3-4), 255–69.
  127. Newson, M. D., (1979), ‘The results of ten years’ experimental study on Plynlimon, mid-Wales and their importance for the Water Industry’, Journal of the Institute of Water Engineers, 33, 321–33.
  128. Newson, M. D. (1980a), ‘The geomorphological effectiveness of floods – a contribution stimulated by two recent events in mid-Wales’, Earth Surface Processes, 5, 1-16.
  129. Newson, M. D. (1980b), ‘The erosion of drainage ditches and its effects on bed-load yields in Mid Wales: reconnaissance case studies’, Earth Surface Processes, 5, 275–90.
  130. Newson, M. D., a Leeks, G. J. L. (1987), ‘Transport processes at a catchment scale: a regional study of increasing sediment yield and its effects in mid-Wales, UK’ yn Thorne, C. R., Bathurst, J. C., a Hey, R. D. (goln), Sediment Transport in Gravel Bed Rivers (Chichester, Wiley & Sons), t.187–218.
  131. North, F. J. (1962), River scenery at the Head of the vale of Neath (Caerdydd, Amgueddfa Genedlaethol Cymru).
  132. Passmore, D. G., Macklin, M. G., Brewer, P. A., et al. (1993), ‘Variability of late Holocene braiding in Britain’, yn Best, J.L., a Bristow C. S. (goln), Braided Rivers (Geological Society of London Special Publication No. 75), t.205–30.
  133. Petts, G. E. (1984), ‘Sedimentation within a regulated river’, Earth Surface Processes and Landforms, 9, 125–34.
  134. Pilling, C.G., a Jones, J.A.A. (2002), ‘The impact of future climate change on seasonal discharge, hydrological processes and extreme flows in the Upper Wye experimental catchment, mid-Wales’, Hydrological Processes, 16, 1201–13.
  135. Price, A. (1977), Quaternary deposits between Llanllioni and Pentreawart, Middle Teifi Valley, Dyfed (Traethawd MSc, Prifysgol Cymru Aberystwyth).
  136. Ramsay, A. C. (1846), ‘The denudation of South Wales and adjacent English counties’, Memoir of the Geological Survey of Great Britain, 1, t.297–335.
  137. Ramsay, A. C. (1866), ‘The Geology of North Wales’, Memoir of the Geological Survey of Great Britain, Cyfrol 3 (argraffiad cyntaf).
  138. Ramsay, A. C. (1881), ‘The Geology of North Wales’, Memoir of the Geological Survey of Great Britain, Cyfrol 3.
  139. Ramsay, A. C., ‘On the physical history of the Dee, Wales’, Quaternary Journal of the Geological Society of London, 32 (876), 219–29.
  140. Rowberry, M. (2007), The influence of climate and base level change on long term drainage network development in the mid-Wales massif (Traethawd doethuriaeth, Prifysgol Cymru Aberystwyth).
  141. Smith, S. A. (1987), ‘Gravel counterpoint nars: Examples from the River Tywi, South Wales’, yn Etheridge, F. G., Flores, R. M., a. Harvey, M. D. (goln), Recent Developments in Fluvial Sedimentology (Society of Economic Palaeontologists and Mineralogists Special Publication Rhif 39), t.75–81.
  142. Smith, S. A. (1989), ‘Sedimentation in a meandering gravel-bed river: the River Tywi, South Wales’, Geological Journal, 24, t.193–204.
  143. Stott, T. (1999), ‘Stream bank and forest ditch erosion, preliminary responses to timber harvesting in mid-Wales’, yn Brown, A. G., a Quine, T. A. (goln), Fluvial Processes and Environmental Change (Chichester, Wiley & Sons), t.47–70.
  144. Taylor, M. P. (1996), ‘The variability of heavy metals in floodplain sediments: a case study from mid Wales’, Catena, 28 (1), 71–87.
  145. Taylor, M. P., a Brewer, P. A. (2001), ‘A study of Holocene floodplain particle size characteristics with special reference to palaeochannel infills from the upper Severn basin, Wales, UK’, Geological Journal, 36, 14357.
  146. Taylor, M. P., a Lewin, J., (1996), ‘River behaviour and Holocene alluviation: the River Severn at Welshpool, mid-Wales, UK’, Earth Surface Processes and Landforms, 21, 77–91.
  147. Taylor, M.P., a Lewin, J. (1997), ‘Non-synchronous response of adjacent floodplain systems to Holocene environmental change’, Geomorphology, 18, 251–64.
  148. Thomas, T. M. (1974), ‘The south Wales interstratal karst’, Transactions of the British Cave Research Association, 1, 131–52.
  149. Thomas, G. S. P., Summers, A. P., a Dackombe, R. V. (1982), ‘The Late Quaternary deposits of the middle Dyfi Valley, Wales’, Geological Journal, 17, 297–309.
  150. Thorne, C. R., a Hey, R. D., (1979), ‘Direct measurement of secondary currents at a river inflexion point’, Nature, 280, 226–28.
  151. Thorne, C R., a Lewin, J. (1979), ‘Bank processes, bed material movement and planform development in a meandering river’, yn Rhodes, D.D., a Williams, G.P. (gol.), Adjustments of 70 the Fluvial System, (Dubuque, Iowa, Kendall/Hunt Publishing Company), t.117–37.
  152. Thorne, C. R., a Tovey, N. K. (1981), ‘Stability of composite river banks,’ Earth Surface Processes and Landforms, 6, 469–84.
  153. van de Wiel, M. J., Coulthard, T. J., Macklin, M. G., et al. (2007), ‘Embedding reach-scale fluvial dynamics within the CAESAR cellular automaton landscape evolution model’,  Geomorphology, 90 (3-4), 283–301.
  154. Walsh, P. T., (2001), The Palaeogeography of the southern half of the British Isles and adjacent Continental Shelf at the Palaeogene/Neogene boundary and its subsequent modification: a reconsideration (Katowice, Wydawnictwo Uniwersytetu Slaskeigo), t.160.
  155. Wilson, C. M., a Smart, P. (1984), ‘Pipes and pipeflow processes in an upland catchment, Wales’, Catena 11, t.145–58.
  156. Wolfenden, P. J., a Lewin, J. (1977), ‘Distribution of metal pollutants in floodplain sediments’, Catena 4, t. 309–17.