Stratigraphical framework for the Middle Jurassic strata of Great Britain and the adjoining continental shelf Geology and Landscape Programme Research Report RR/11/06 BRITISH GEOLOGICAL SURVEY RESEARCH REPORT RR/11/06 The National Grid and other Stratigraphical framework for the Ordnance Survey data © Crown copyright and database rights 2012. Ordnance Survey Licence Middle Jurassic strata of Great No. 100021290 Britain and the adjoining Key words Geology, stratigraphy, lithostratigraphy, Inferior Oolite continental shelf Group, Great Oolite Group, Ravenscar Group, Great Estuarine Group, Sutherland Group, Ancholme Group, Jurassic. A J M Barron, G K Lott, J B Riding Front cover Hilltop Quarry, Leckhampton Hill, Cheltenham, Glos.: the Birdlip Limestone Formation overlain by the Aston Limestone Formation. (P775213, A J M Barron) Bibliographical reference BARRON, A J M, LOTT, G K, AND RIDING, J B. 2012. Stratigraphical framework for the Middle Jurassic strata of Great Britain and the adjoining continental shelf. British Geological Survey Research Report, RR/11/06. 187pp. ISBN 978 0 85272 695 2 Copyright in materials derived from the British Geological Survey’s work is owned by the Natural Environment Research Council (NERC) and/or the authority that commissioned the work. You may not copy or adapt this publication without first obtaining permission. Contact the BGS Intellectual Property Rights Section, British Geological Survey, Keyworth, e-mail [email protected]. You may quote extracts of a reasonable length without prior permission, provided a full acknowledgement is given of the source of the extract. Maps and diagrams in this book use topography based on Ordnance Survey mapping. © NERC 2012 Keyworth, Nottingham British Geological Survey 2012 BRITISH GEOLOGICAL SURVEY The full range of our publications is available from BGS shops at British Geological Survey offices Nottingham, Edinburgh, London and Cardiff (Welsh publications only) see contact details below or shop online at www.geologyshop.com BGS Central Enquiries Desk Tel 0115 936 3143 Fax 0115 936 3276 The London Information Office also maintains a reference collection of BGS publications, including maps, for consultation. email [email protected] We publish an annual catalogue of our maps and other publications; this catalogue is available online or from any of the Kingsley Dunham Centre, Keyworth, Nottingham NG12 5GG BGS shops. 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Natural History Museum, Cromwell Road, London SW7 5BD Tel 020 7589 4090 Fax 020 7584 8270 Tel 020 7942 5344/45 email [email protected] Columbus House, Greenmeadow Springs, Tongwynlais, Cardiff CF15 7NE Tel 029 2052 1962 Fax 029 2052 1963 Maclean Building, Crowmarsh Gifford, Wallingford OX10 8BB Tel 01491 838800 Fax 01491 692345 Geological Survey of Northern Ireland, Colby House, Stranmillis Court, Belfast BT9 5BF Tel 028 9038 8462 Fax 028 9038 8461 www.bgs.ac.uk/gsni/ Parent Body Natural Environment Research Council, Polaris House, North Star Avenue, Swindon SN2 1EU Tel 01793 411500 Fax 01793 411501 www.nerc.ac.uk Website www.bgs.ac.uk Shop online at www.geologyshop.com Foreword This report is the published product of a study by the British Geological Survey (BGS) Stratigraphical Framework Committee (SFC) for the Middle Jurassic strata of Great Britain. The report provides a summary of the lithostratigraphical scheme proposed by the SFC that aims to rationalise group and formation nomenclature for the Middle Jurassic of the entire onshore and the adjoining offshore areas of Great Britain. This framework report provides detailed descriptions of group and formation nomenclature, specifically for the onshore area of Great Britain covering southern England, the Cleveland Basin, the Moray Firth Basin (onshore) and the Hebrides Basin. It also gives outline lithostratigraphical information regarding the offshore areas of the English Channel, Western Approaches and St George′s Channel–Cardigan Bay, and the UK area of the North Sea. The report provides criteria for rationalisation of existing nomenclature where necessary. Existing names are used wherever appropriate, although where formation names have not previously existed or are unsatisfactory, the report proposes and rationalises a new nomenclature and provides a full description. Acknowledgements The authors would like to thank many current and former BGS colleagues for helpful discussion and suggestions, in particular M G Sumbler, B M Cox, J H Powell, D Stephenson and I J Andrews who advised on parts of this document and who created many of the lexicon entries on which this document draws. Outside BGS, the late Professor J H Callomon, Dr J K Wright and R B Chandler are acknowledged for helpful comments and discussions and the provision of documentation, some unpublished. Thanks are also due to the Geological Society Stratigraphy Commission and their reviewers for comment and suggestions incorporated in this document. This report has been compiled on behalf of the BGS Stratigraphy Committee, and inevitably reflects a large degree of pragmatism and compromise. The final form of the formational framework is not necessarily the preferred version of all the authors but, nevertheless, it provides a workable scheme within which any new data and subdivision can be accommodated. If users of this document discover inconsistencies or factual errors in the specifications given for the various lithostratigraphical units, they are encouraged to notify A J M Barron, British Geological Survey, Keyworth, Nottingham, NG12 5GG (email [email protected]). British Geological Survey Research Report RR/11/06 v Contents Foreword ........................................................................................................................................ v Acknowledgements ........................................................................................................................ v Contents ......................................................................................................................................... vi Summary ....................................................................................................................................... ix 1 Introduction ............................................................................................................................ 1 2 Palaeogeography and basin definitions ................................................................................ 5 2.1 Southern Britain (Cotswold, Wessex, Weald, Channel, Western Approaches, Bristol Channel and St George′s Channel–Cardigan Bay basins) ....................................................... 8 2.2 Southern Britain (East Midlands Shelf, Cleveland Basin and southern North Sea) ..... 10 2.3 Moray Firth Basin ......................................................................................................... 11 2.4 Hebrides Basin .............................................................................................................. 12 2.5 Rockall–Faroes Rift ...................................................................................................... 14 3 Biostratigraphical and chronostratigraphical framework ............................................... 15 4 Lithostratigraphical framework: group level .................................................................... 17 5 Southern and eastern England ............................................................................................ 23 5.1 Inferior Oolite Group .................................................................................................... 23 5.1.1 Birdlip Limestone Formation .................................................................................... 30 5.1.2 Aston Limestone Formation ...................................................................................... 32 5.1.3 Salperton Limestone Formation ................................................................................ 34 5.1.4 Northampton Sand Formation ................................................................................... 36 5.1.5 Grantham Formation ................................................................................................. 38 5.1.6 Lincolnshire Limestone Formation ........................................................................... 41 5.2 Great Oolite Group ....................................................................................................... 45 5.2.1 Fuller’s Earth Formation ........................................................................................... 49 5.2.2 Frome Clay Formation .............................................................................................. 52 5.2.3 Forest Marble Formation ........................................................................................... 53 5.2.4 Cornbrash Formation ................................................................................................. 56