Hostname: page-component-848d4c4894-wzw2p Total loading time: 0 Render date: 2024-05-16T10:41:48.050Z Has data issue: false hasContentIssue false
  • English
  • Français

Clay mineralogy of the Tertiary onshore and offshore strata of the British Isles

Published online by Cambridge University Press:  09 July 2018

J. M. Huggett  and
R. W. O'B. Knox
J. M. Huggett*
Affiliation:
Department of Mineralogy, Natural History Museum, Cromwell Road, London SW7 5BD, UK Petroclays, 15 Gladstone Rd, Ashtead, Surrey KT21 2NS, UK
R. W. O'B. Knox
Affiliation:
British Geological Survey, Keyworth, Nottingham NG12 5GG, UK
*
*E-mail: jmhuggett@petroclays.demon.co.uk
Get access Rights & Permissions [Opens in a new window]

Abstract

Tertiary sediments are of restricted occurrence in the onshore British Isles but occur extensively offshore, attaining thicknesses of ~4 km in the Faroe—Shetland Basin and ~3 km in the North Sea Basin. Clay mineral stratigraphic studies of the North Sea Paleocene to Lower Miocene successions show a dominance of smectite (and smectite-rich illite-smectite) with minor illite, kaolin and chlorite. Abundant smectite in the Paleocene and Eocene reflects alteration of volcanic ash derived from pyroclastic activity associated with the opening of the North Atlantic between Greenland and Europe. However, the persistence of high smectite into the Oligocene and Middle Miocene indicates that smectite-rich soils on adjacent land areas may also have been an important source of detrital clays. An upwards change to illite-dominated assemblages in the Middle Miocene reflects higher rates of erosion and detrital clay supply, with a subsequent increase in chlorite reflecting climatic cooling. The persistence of smectite-rich assemblages to depths of >3000 m in the offshore indicates little burial-related diagenesis within the mudstone succession, possibly as a consequence of over-pressuring. Despite the importance of Paleocene and Eocene sandstones as hydrocarbon reservoirs in the North Sea and Faroe-Shetland basins, there are few published details of the authigenic clays. The principal clay cements in these sandstones are kaolin and chlorite, with only minor illite reported.

The offshore successions provide a valuable background to the interpretation of the more intensively studied, but stratigraphically less complete, onshore Tertiary successions. The most extensive onshore successions occur in the London and Hampshire basins where sediments of Paleocene to earliest Oligocene age are preserved. Here clay assemblages are dominated by illite and smectite with subordinate kaolin and chlorite. The relatively large smectite content of these successions is also attributed primarily to the alteration of volcanic ash. Associated non-smectitic clays are largely detrital in origin and sourced from areas to the west, with reworking of laterites and “china clay” deposits developed over Cornish granites. Authigenic clays include glauconite (sensu lato), early diagenetic kaolin that has replaced muscovite (principally in the London Clay Formation of the London Basin) and smectite that has replaced ash. Pedogenesis has extensively modified the assemblages in the Reading Formation and Solent Group. Tertiary sediments are largely missing from onshore northern and western Britain, but clays and sands of Eocene and Oligocene age are locally preserved in small fault-bounded basins. Here, clay assemblages are dominated by kaolin with minor illite.

Keywords

Tertiaryclay mineralogystratigraphyBritish Isles
Type
Research Article
Information
Clay Minerals , Volume 41 , Issue 1 , March 2006 , pp. 5 - 46
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2006

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Arthurton, R.S., Booth, S.J., Morigi, A.N., Abbott, M.A.W. & Wood, C.J. (1994) Geology of the country around Great Yarmouth. Memoirs of the British Geological Survey. Sheet Memoir 162 (England and Wales). 138 pp.Google Scholar
Bain, J.A., Stacey, F.R. & Morgan, D.J. (1976) Composition, properties and potential uses of Lough Neagh clays, Ballynakilly, Northern Ireland. Geological Survey of Northern Ireland Open-file Report, 58.Google Scholar
Baioumy, H.M. & Hassan, M.S. (2004) Authigenic halloysite from El-Gideda iron ore, Bahira Oasis, Egypt: characterization and origin. Clay Minerals, 39, 207–218 Google Scholar
Berstad, S. & Dypvik, H. (1982) Sedimentological evolution and natural radioactivity of Tertiary sediments from the Central North Sea. Journal of Petroleum Geology, 5, 77–88.CrossRefGoogle Scholar
Bowers, T.S. & Burns, R.G. (1990) Activity diagrams for clinoptilolite: susceptibility of this zeolite to further diagenetic reactions. American Mineralogist, 75, 601–619.Google Scholar
Bristow, C.M. (1968) Derivation of Tertiary Sediments in the Petrockstow Basin. Proceedings of the Ussher Society, 2, 29–35.Google Scholar
Bristow, C.R., Freshney, C.R. & Penn, I.E. (1991) Geology of the country around Bournemouth. Memoirs of the British Geological Survey. Sheet Memoir 329 (England and Wales), 116 pp.Google Scholar
Buchardt, B. (1978) Oxygen isotope palaeotemperatures from the Tertiary period in the North Sea area. Nature (London), 275, 121–123.CrossRefGoogle Scholar
Burnett, A. & Fookes, P.G. (1974) A regional engineering study of the London Clay in the London and Hampshire Basins. Quarterly Journal of Engineering Geology London, 7, 257–295.Google Scholar
Buurman, P. (1980) Palaeosols in the Reading Beds (Palaeocene) of Alum Bay, Isle of Wight, UK. Sedimentology, 27, 593–606.Google Scholar
Carruth, A.G. (2003) The Foinaven Field, Blocks 204/19 and 204/24a, UK North Sea. Pp. 121–130 in: United Kingdom Oil and Gas Fields Commemorative Millennium Volume (Gluyas, J.G. & Hichens, H.M., editors). Memoir No. 20, Geological Society, London.Google Scholar
Chadwick, R.A. (1993) Aspects of basin inversion in southern Britain. Journal of the Geological Society, London, 150, 311–322.Google Scholar
Chandler, P.M. & Dickinson, B. (2003a) The Maureen Field, Block 16/29a, UK Central North Sea. Pp. 587–601 in: United Kingdom Oil and Gas Fields Commemorative Millennium Volume (Gluyas, J.G. & Hichens, H.M., editors). Memoir No. 20, Geological Society, London.Google Scholar
Chandler, P.M. & Dickinson, B. (2003b) The Moira Field, Block 16/29a, UK Central North Sea. Pp. 603–609 in: United Kingdom Oil and Gas Fields Commemorative Millennium Volume (Gluyas, J.G. & Hichens, H.M., editors). Memoir No. 20, Geological Society, London.Google Scholar
Clauer, N., Huggett, J.M. & Hillier, S. (2005) How reliable is the K-Ar glauconite chronometer? A case study of Eocene sediments from the Isle of Wight. Clay Minerals, 40, 167–176.Google Scholar
Cosgrove, M.E. & Salter, D.L. (1966) The stratigraphical distribution of kaolinite in the post-Amorican formations of south-west England. Proceedings of the Ussher Society, 1, 245–252.Google Scholar
Cox, F.C., Hailwood, E.A., Harland, R., Hughes, M.J., Johnston, N. & Knox, R.W. O'B (1985) Palaeocene sedimentation and stratigraphy in Norfolk, England. Newsletters in Stratigraphy, 14, 169–185.Google Scholar
Daley, B. (1972) Some problems concerning the Early Tertiary climate of southern Britain. Palaeogeography, Palaeoclimatology , Palaeoecology, 11, 177–190.CrossRefGoogle Scholar
Daley, B. & Balson, P. (1999) British Tertiary Stratigraphy. Geological Conservation Review Series, No. 15, Joint Nature Conservation Commission, UK.Google Scholar
Deyu, Z. (1987) Clay mineralogy of the Upper Palaeocene clay sediments in Denmark. Bulletin of the Geological Society of Denmark, 36, 249–258.CrossRefGoogle Scholar
Doré, A.G., Lundin, E.R., Jensen, L.N., Birkeland, Ø., Eliassen, P.E. & Filcher, C. (1999) Principal tectonic events in the evolution of the northwest European Atlantic margin. Pp. 41–61 in: Petroleum Geology of Northwest Europe: Proceedings of the 5th Conference (Fleet, A.J. & Boldy, S.A.R., editors). Geological Society, London, 1398 pp.Google Scholar
Edwards, R.A. & Freshney, E.C. (1987) Geology of the country around Southampton. Memoirs of the British Geological Survey. Sheet Memoir 315 (England and Wales), 111 pp.Google Scholar
Elliott, G.F. (1971) Eocene volcanics in south-east England. Nature, Physical Sciences London, 230, 9.Google Scholar
Ellison, R.A. (1976) Braintree and Sudbury sheets. Pp. 20–21 in: IGS Boreholes 1975. Report of the Institute of Geological Sciences, No. 76/10.Google Scholar
Ellison, R.A. (2004) Geology of London. Special Memoir for 1:50 000 Geological Sheets 256 (North London), 257 (Romford), 270 (South London) and 271 (Dartford) (England and Wales). British Geological Survey, x + 114 pp.Google Scholar
Ellison, R.A. & Knox, R.W.O'B. (1978) Colchester sheet. P. 3 in: IGS boreholes 1977. Report of the Institute of Geological Sciences, No. 78/21.Google Scholar
Ellison, R.A. & Lake, R.D. (1986) Geology of the country around Braintree. Memoirs of the British Geological Survey. Sheet Memoir 223 (England and Wales), 69 pp.Google Scholar
Ellison, R.A., Lake, R.D. & Moorlock, B.S.P. (1978) Braintree and adjacent sheets. Pp. 5–9 in: IGS Boreholes 1976. Report of the Institute of Geological Sciences, No 77/10.Google Scholar
Ellison, R.A., Knox, R.W.O'B., Jolley, D.W. & King, C. (1994) A revision of the lithostratigraphical classification of the early Palaeocene strata of the London Basin and East Anglia. Proceedings of the Geologists' Association, 105, 187–197.Google Scholar
Evans, D., Hallsworth, C., Jolley, D.W. & Morton, A.C. (1991) Late Oligocene Terrestrial sediments from a small basin in the Little Minch. Scottish Journal of Geology, 27, 33–40.CrossRefGoogle Scholar
Fisher, O. (1862) On the Bracklesham Beds of the Isle of Wight Basin. Quarterly Journal of the Geological Society London, 18, 65–94.Google Scholar
Fitzpatrick, E.A. (1963) Deeply weathered rock in Scotland, its occurrence, age and contribution to the soils. Journal of Soil Science, 14, 33–43.Google Scholar
Gale, A.S., Jeffery, P.A., Huggett, J.M. & Connolly, P. (1999) Eocene inversion history of the Sandown Pericline, Isle of Wight, southern England. Journal of the Geological Society, London, 156, 327–339.CrossRefGoogle Scholar
Gale, A.S., Huggett, J.M., Palike, H., Laurie, E., Hailwood, E., Hardenbol, J. & Jeffery, P.A. (2006) Correlation of Eocene-Oligocene marine and continental records: orbital cyclicity, magneto- and sequence stratigraphy of the Solent Group, Isle of Wight, UK. Journal of the Geological Society, London, 163, 401–415 CrossRefGoogle Scholar
Gambaro, M. & Currie, M. (2003) The Balmoral, Glamis and Stirling fields, block 16/21, UK Central North Sea. Pp. 395–413 in: United Kingdom Oil and Gas Fields Commemorative Millennium Volume (Gluyas, J.G. & Hichens, H.M., editors). Memoir No. 20, Geological Society, London.Google Scholar
Gibbard, P.L. & Lewin, J. (2003) The history of major rivers in southern Britain during the Tertiary. Journal of the Geological Society, London, 160, 829–846.Google Scholar
Gilkes, R.J. (1966) The Clay Mineralogy of the Tertiary Sediments of the Hampshire Basin. PhD thesis, University of Southampton, UK.Google Scholar
Gilkes, R.J. (1968) Clay mineral provinces in the Tertiary sediments of the Hampshire Basin. Cla Minerals, 7, 351–361.Google Scholar
Gilkes, R.J. (1978) On the clay mineralogy of upper Eocene and Oligocene sediments in the Hampshire Basin. Proceedings of the Geologists' Association, 89, 43–56.CrossRefGoogle Scholar
Hamblin, R.J.O. (1973) Clay Mineralogy of the Haldon Gravels. Clay Minerals, 10, 87–97.Google Scholar
Hancock, J.C. (1986) Cretaceous. Pp. 161–178 in: Introduction to the Petroleum Geology of the North Sea (second edition) (Glennie, K.W., editor). Blackwell, Oxford, UK, 278 pp.Google Scholar
Heilmann-Clausen, C., Nielsen, O.B. & Gersner, F. (1985). Lithostratigraphy and depositional environments in the Upper Paleocene and Eocene of Denmark. Bulletin of the Geological Society of Denmark, 33, 287–323 Google Scholar
Herbert-Smith, M. (1971) Palynology of the Tertiary and Pleistocene deposits of the Llanbedr (Mochras Farm) borehole. P. 155 in: The Llanbedr (Mochras Farm) borehole (Woodland, A.W., editor). Report of the Institute of the Geological Sciences, No. 71/18.Google Scholar
Hight, D.W., Ellison, R.A. & Page, D.P. (2004) Engineering in the Lambeth Group. CIRIA, London, 39 pp.Google Scholar
Huggett, J.M. (1992) Petrography, mineralogy and diagenesis of overpressured Tertiary and late Cretaceous mudstones from the East Shetland Basin. Clay Minerals, 27, 487–506.Google Scholar
Huggett, J.M. (1994) Diagenesis of mudstones and concretions from the London Clay Formation in the London Basin. Clay Minerals, 29, 693–707.Google Scholar
Huggett, J.M. (1996) Aluminosilicate diagenesis in a Tertiary sandstone-mudstone sequence from the central North Sea, U.K. Clay Minerals, 31, 523–536.Google Scholar
Huggett, J.M. & Cuadros, J. (2005) Low temperature illitisation of smectite in the Late Eocene and Early Oligocene of the Isle of Wight (Hampshire Basin), UK. American Mineralogist, 90, 1192–1202.Google Scholar
Huggett, J.M. & Gale, A.S. (1997) Petrology and palaeoenvironmental significance of glaucony in the Eocene succession at Whitecliff Bay, Hampshire Basin, UK. Journal of the Geological Society, London, 154, 897–912.Google Scholar
Huggett, J.M. & Gale, A.S. (1998) Petrography and diagenesis of the Thames Group at Whitecliff Bay, Isle of Wight, UK. Proceedings of the Geologists' Association, 109, 99–113.CrossRefGoogle Scholar
Huggett, J.M., Gale, A.S. & Clauer, N. (2001) The nature and origin of non-marine 10 green clays from the Å late Eocene and Oligocene A of the Isle of Wight (Hampshire Basin), UK. Clay Minerals, 36, 447–464.Google Scholar
Huggett, J.M., Gale, A.S. & Wray, D.S. (2005) diagenetic clinoptilolite and opal-CT from the Middle Eocene Wittering Formation, Isle of Wight, UK. Journal of Sedimentary Research, 75, 585–595.Google Scholar
Isaac, K.P. (1983) Tertiary lateritic weathering in Devon, England, and the Palaeogene continental environment of South West England. Proceedings of the Geologists' Association, 94, 105–114.CrossRefGoogle Scholar
Jacqué, M. & Thouvenin, J. (1975) Lower Tertiary tuffs and volcanic activity in the North Sea. Pp. 455–465 in: Petroleum and the Continental Shelf of North-West Europe. (Woodland, A.W., editor). Applied Science Publishers, Barking, Essex, UK, 501 pp.Google Scholar
Jeans, C.V., Merriman, R.J. & Mitchell, J.G. (1977) Origin of Middle Jurassic and Lower Cretaceous Fuller's Earths in England. Clay Minerals, 12, 11–44.CrossRefGoogle Scholar
Karlsson, W., Vollset, J., Bjørlykke, K. & Jørgensen, P. (1979) Changes in mineralogical composition of Tertiary sediments from North Sea wells. Pp. 281–289 in: Proceedings of the 6th International Clay Conference, Oxford, 1978 (Mortland, M.M. & Farmer, V.C., editors) . Developments in Sedimentology, 27, Elsevier, Amsterdam.Google Scholar
Kennett, J.P. and von der Borch, C.C. (1986) Southwest Pacific Cenozoic paleooceanography. Initial Reports of the DSDP, 90, 1493–1517.Google Scholar
King, C. (1981) The Stratigraphy of the London Clay and Associated Deposits. Tertiary Research (Special Paper), 6, 3–158.Google Scholar
Knox, R.W.O'B. (1979) Igneous grains associated with zeolite in the Thanet Beds of Pegwell Bay north-east Kent. Proceedings of the Geologists̕ Association, 90, 55–59.Google Scholar
Knox, R.W.O'B. (1983) Volcanic ash in the Oldhaven Beds of southeast England, and its stratigraphical significance. Proceedings of the Geologists' Association, 94, 245–250.Google Scholar
Knox, R.W.O'B. (1996) Correlation of the early Paleogene in northwest Europe: an overview. Pp. 1–11 in: Correlation of the Early Paleogene in Northwest Europe, (Knox, R.W. O'B., Corfield, R.M. & Dunay, R.E., editors). Special Publication, 101, Geological Society, London,Google Scholar
Knox, R.W.O'B. (2002) Tertiary sedimentation. Pp. 361–370 in: The Geology of Scotland (fourth edition) (Trewin, N.H., editor). Geological Society, London, 576 pp.Google Scholar
Knox, R.W.O'B. & Morton, A.C. (1983) Stratigraphical distribution of early Palaeogene pyroclastic deposits in the North Sea Basin. Proceedings of the Yorkshire Geological Society, 44, 355–363.Google Scholar
Knox, R.W.O.B. & Morton, A.C. (1988) The record of early Tertiary N Atlantic volcanism in sediments of the North Sea Basin. Pp. 407–419 in: Tertiary Volcanism and the Opening of the NE Atlantic (Morton, A.C. and Parson, L.M., editors). Special Publication, 39, Geological Society, London.Google Scholar
Knox, R.W.O'B. & Holloway, S. (1992) Paleogene of the Central and Northern North Sea. In: Lithostratigraphic Nomenclature of the UK North Tertiary clay mineralogy of the British Isles 45 Sea (Knox, R.W.O'B. & Cordey, W.G., editors). British Geological Survey, Keyworth.Google Scholar
Knox, R.W.O'B., Morigi, A.N., Ali, J.R. , Hailwood, E.A. & Hallam, J.R. (1990) Early Palaeogene stratigraphy of a cored borehole at Hales, Norfolk. Proceedings of the Geologists' Association, 101, 145–151.CrossRefGoogle Scholar
Kunka, J.M., Williams, G., Cullen, B., Boyd-Gorst, J., Dyer, G.R., Garnham, J.A., Warnock, A., Wardell, J., Davis, A. & Lynes, P. (2003) The Nelson Field, Blocks 22/11, 22/6a, 22/7, 22/12a, UK North Sea. Pp. 617–646 in: United Kingdom Oil and Gas Fields Commemorative Millennium Volume (Gluyas, J.G. & Hichens, H.M., editors). Memoir No. 20, Geological Society, London,.Google Scholar
Lake, R.D., Ellison, R.A., Henson, M.R. & Conway, B.W. (1986) Geology of the Country around Southend and Foulness. Memoir of the British Geological Survey. Sheet Memoirs 258&259 (England and Wales), 85 pp.Google Scholar
Lott, G.K., Knox, R.W.O'B., Harland, R. & Hughes, M.J. (1983). The stratigraphy of Palaeogene sediments in a cored borehole off the coast of north-east Yorkshire. Report of the Institute of Geological Sciences No. 83/9.Google Scholar
Loveland, P.J. (1981) Weathering of a soil glauconite in southern England. Geoderma, 25, 35–54.CrossRefGoogle Scholar
Loveland, P.J. & Findlay, D.C. (1982) Composition and development of some soils on glauconitic Cretaceous (Upper Greensand) rocks in southern England. Journal of Soil Science, 33, 279–294.CrossRefGoogle Scholar
Malm, O.A., Bruun Christensen, O., Furnes, H., Løvlie, R. & Rueslatten, H. (1984) The Tertiary Balder Formation: an organogenic and tuffaceous deposit in the North Sea region. Pp. 149–170 in: Petroleum Geology of the North European Margin (Spencer, A.M., editor). Graham & Trotman, London, 436 pp.Google Scholar
Mitchell, D. and Stentiford, M.J. (1973) Die Gewinnung und die Eigenschaften von Plastischem Ton aus dem Devon (The production and properties of Devon Ball Clays). Journal Selikat, 12, 185–94.Google Scholar
Moorlock, B.S.P, Hamblin, R.J.O., Booth, S.J. & Moriji, A.N. (2000) Geology of the country around Lowestoft and Saxmundham. Memoirs of the British Geological Survey. Sheet Memoirs 176&191 (England and Wales).Google Scholar
Nielsen, O. B. (1979) A sedimentological mineralogical investigation of the Tertiary sediments from the borehole M-2X in Central Trough, North Sea. Danmarks Geologisk Undersøgelse Årbog, 41–50.Google Scholar
Norwegian Petroleum Directorate (1988) Well Data Summary Sheets, Vol. 13, Part II. Wells completed 1982. Google Scholar
Norwegian Petroleum Directorate (1990) Well Data Summary Sheets, Vol. 15, Part II. Wells completed 1984. Google Scholar
Norwegian Petroleum Directorate (1992) Well Data Summary Sheets, Vol. 17, Part II. Wells completed 1986. Google Scholar
Odin, G.S. (1988) Glaucony from the Gulf of Guinea. Pp. 225–247 in: Green Marine Clays (Odin, G.S., editor). Developments in Sedimentology, 45. Elsevier, Amsterdam.Google Scholar
Page, D. & Skipper, J.A. (2000) Lithological characteristics of the Lambeth Group. Ground Engineering, 33, 38–43.Google Scholar
Pearson, M.J. (1990) Clay mineral distribution and provenance in Mesozoic and Tertiary mudrocks of the Moray Firth and Northern North Sea. Clay Minerals, 25, 519–541.Google Scholar
Pearson, M.J. & Small, J.S. (1988) Illite-smectite diagenesis and palaeotemperatures in northern North Sea Quaternary to Mesozoic shale sequences. Clay Minerals, 23, 109–132.Google Scholar
Perrin, R.M.S. (1971) The Clay Mineralogy of British Sediments. Mineralogical Society, London, 247 pp.Google Scholar
Prothero, D.R., Ivany, L.C. & Nesbitt, E.A. (editors) (2003) From Greenhouse to Icehouse; the Marine Eocene–Oligocene Transition. Columbia University Press, New York, 541 pp.Google Scholar
Robert, C. & Chamley, H. (1991) Development of early Eocene warm climates, as inferred from clay mineral variation in oceanic sediments. Palaeogeography, Palaeoclimatology, Palaeoecology (Global and Planetary Change), 89, 315–332.Google Scholar
Sellwood, E.B., Edwards, R.A., Simpson, S., Chesher, J.A., Hamblin, R.J.O., Henson, M.R., Riddolls, B.W. & Waters, R.A. (1984) Geology of the country around Newton Abbot. Memoirs of the British Geological Survey. Sheet Memoir, 339 (England and Wales), 212 pp.Google Scholar
Skipper, J.A. (1999) The Stratigraphy of the Lambeth Group (Palaeocene) of south east England. PhD thesis University of London.Google Scholar
Stewart, R.N.T., Fallick, A.E. and Haszeldine, R.S. (1994) Kaolinite growth during pore-water mixing: isotopic data from Palaeocene sands, North Sea, UK. Clay Minerals, 29, 627–636.Google Scholar
Sullivan, M., Coombes, T., Imbert, P. & Ahamdach-Demars, C. (1999) Reservoir quality and petrophysi-cal evaluation of Paleocene sandstones in the West of Shetland area. Pp. 627–633 in: Petroleum Geology of Northwest Europe: Proceedings of the 5th Conference (Fleet, A.J. & Boldy, S.A.R., editors). Geological Society, London, 1398 pp.Google Scholar
Tonkin, P.C. & Fraser, A.R. (1991) The Balmoral Field, Block 16/21, UK North Sea. Pp. 237–243 in: United Kingdom Oil and Gas Fields 25 Years Commemorative Volume (Abbotts, I.L., editor). Memoir No. 14, Geological Society, London.Google Scholar
Vincent, A. (1983) The origin and occurrence of Devon Ball Clays. Pp. 39–45 in. Residual Deposits: Surface Related Weathering Processes and Materials (Wilson, R.C.L., editor). Special 46 Huggett, J. M. and Knox, R. W. O'B. Publication 11, Geological Society of London.Google Scholar
Weir, A.H. & Catt, J.A. (1965) The mineralogy of some Upper Chalk samples from the Arundel area, Sussex. Clay Minerals, 6, 97–110.Google Scholar
Weir, A.H. & Catt, J.A. (1969) The mineralogy of Palaeogene sediments in northeast Kent (Great Britain). Sedimentary Geology, 3, 17–13.Google Scholar
Wensaas, L., Shaw, H.F., Gibbons, K., Agaard, P. & Dypvik, H. (1994) Nature and causes of overpressur-ing in mudrocks of the Gullfaks area, North Sea. Clay Minerals, 29, 439–449.Google Scholar
Wills, J.M. (1991) The Forties Field, Block 21/10, 22/6a, UK North Sea. Pp. 301–308 in United Kingdom Oil and Gas Fields 25 Years Commemorative Volume (Abbotts, I.L., editor). Memoir No. 14, Geological Society, London.Google Scholar
Wilson, M.J., Bain, D.C. & Duthie, M.L. (1984) The soil clays of Great Britain: II. Scotland. Clay Minerals, 19, 709–735.Google Scholar
Woodland, A.W. (1971) The Llanbedr (Mochras Farm) borehole. Report of the Institute of Geological Sciences No. 71/18, 115 pp.Google Scholar
Woodland, A.W. (1971) The Llanbedr (Mochras Farm) borehole. Report of the Institute of Geological Sciences No. 71/18, 115 pp.Google Scholar