Property of WJ Groundwater

Total Page:16

File Type:pdf, Size:1020Kb

Property of WJ Groundwater Groundwater WJ Dr Toby Roberts FRENG of WJ GROUNDWATER LTD Depressurisation strategies in the PropertyLambeth Group River Terrace Deposits Terrace Gravels Upper Aquifer London Clay Aquiclude Thames Group Harwich Forma:on Upper MoDled Beds Intermediate Aquifer Cohesive + granular Laminated Beds Lambeth Group laminaons to channels Lower Shelly Beds Mid-Lambeth Hiatus Lower MoDled Beds + occ sand channels Upnor Lower Aquifer Thanet Sand Thanet Sand Formaon Bullhead Beds Chalk Chalk London basin typical soil profile Lambeth Group/ Upper Mottled Beds Intermediate Aquifer Depth: 5 to 60 m to top Laminated Beds: Stiff Clay Thickness: 15 to 20 m Predominantly cohesive Channel Sands Granular horizons range Groundwater Reduced from laminaons to MLH sand channels: WJ Oxidised width: 2 to 300 m length: ? of correlaon with lost Rivers Lower Mottled Beds: Stiff Clay Thickness: mms to 12 m Property Crossrail: Stepney Grn EB Groundwater WB WJ Caverns of 100 m long 40 m apart 8 to 17 m wide Property 62 installaons Groundwater WJ of Property Non-hydrostac Recharge required to sustain profile Boundary Condions: Source of recharge? • Seepage from London Clay Very low permeability • Leakage via fissures or scour features Scour features relavely rare, lile evidence Groundwater • Seepage via ungrouted wells or boreholes WJ Plenty of them but not much evidence of • Horizontal flow from areas with higher groundwater Significant distances involved Property Wellpoint Groundwater pumps WJ of Access constrained in an advancing SCLProperty cavern 45 Surface ejectors EB WB 105 tunnel wellpoints Crossrail: Stepney Grn Crossrail: East London Stepney Grn Cross passage CP6 Groundwater WJ of Works impacted by Lambeth Group Property mTD LW9 Made Ground 110 River Terrace Deposits Cross Passage CP6 A3 LW9 approximately 10 m away 100 Lambeth soils above MLH cohesive London Clay Sump extends below MLH: 90 A2 Ejector dewatering required Groundwater WJ 80 Eastof Bound West Bound UMB 71.21 71.21 70 LTB MLH LMB 67.12 LambethGroup PropertyUF 60 Thanet Sand Groundwater WJ of Property Sump ejector system mTD As built: Combined probe holes and wells 80 WU2/4 WU1/3 PR4/9 PR1 EB WB PR6 WP2 UMB WP3 PR3/8 71.21 Groundwater 71.21 LTB NW19 NW13/14 70 NW18 NW1/2 EJ3 WJNW16 MLH NW7 NW15 PR10 LMB NW6 67.12 NW17 PR5 NW8/11 ofWP7/14 WP8/13 WP19/22 WP18/23 Lambeth Group NW3/5 NW9 NW4 UF EJ2 P1 NW10 EJ4 EJ5 60 Thanet Sand EJ1/6 LW9 Property Groundwater WJ of Property Groundwater WJ of Property Groundwater WJ of Property mTD LONDON CLAY 80 EB WB UMB SAND CHANNEL 73.150 UPPER MOTTLEDGroundwater BEDS LEVEL OF CONCRETE LTB 70.64 mTD 70 WJ LAMINATED BEDS LMB of 67.12 mTD LOWER MOTTLEED BEDS 65.95 mTD UPNOR FORMATION UF 60 Thanet Sand LW9 Property NW7 NW6 NW5 NW8 NW13 NW14 NW4 NW9 EJ6 PR6 NW15 EJ5 NW3 EJ4 PR10 As built: NW2 NW16 NW1 NW10EJ2 EJ3 P1 NW11 EJ1 WP3 NW12 East Bound PR1 NW17 WU2 Plan View PR5 NW18 NW19 NW20 WP2 EJ8 LW9 PR8 TCBs WP15A WP16 GroundwaterWP14A WP15 WP14 PR3 WU2B WP13 WP12PR9 WP28 WP11 WU1 WP26 WP25 WJ WU4 WP10 WP27 WP24 WP24a EJ7 WU3 PR4 WP9 WP23 WP7 WP8 WP22 of WP30 WP21 WP6 WP29 WP5 WP20 West Bound WP19 WP17 WP18 Key: Sump ejectors Downwards probes/wellponts Property0 5m Upwards probes/wellpoints Scale not installed Groundwater WJ of Property Technique Site Notes Passive relief wells Whitechapel Shas, Limmo Pressure relief Surface deepwells Valence Gardens Extensive channel sands Surface ejectors Stepney Grn, Cross passages Extensive channel sands Groundwater Tunnel wellpoints LIV/WHI, Cross passages Overbleed WJ Tunnel ejectors VD4, Cross passage sumps of >5 m drawdown Under drainage Some cross passages Proven Lower Aquifer link Crossrail dewatering: Techniques used to target Lambeth Group Property Groundwater WJ Lambeth Groupof CIRIA: C515 LambethProperty Group: Permeability range Excess pore pressure? Channel sands Laminated beds Lithology: Laminaons Layer Sand Channel Unknown? Groundwater Elevaon: Pressure relief WJ Dewatering of Overbleed Access: Constraints Opportunies Dewatering scheme drivers: Lithology and Geometry Property Dr Toby Roberts FRENG WJ GROUNDWATER LTD Dewatering strategies GroundwaterIn the Lambeth Group WJ of Crossrail Liverpool Stn: VD4 inclined SCL tunnel: tunnel ejector system Property .
Recommended publications
  • Geology of the London Basin
    Geology of the London Basin - 100 Million Years in the Making on 16 November 2018 Mr Philip Laurie first showed a geological map of London produced in 1848 by Stanford – the first of its kind. The Earth is 46,000 million years old, so much had happened before the London area made an appearance. The geological history of London started a hundred million years ago. For 60% of that time it has been under ice, causing sea levels to fall. He lives near the Ravensbourne, which rises south of the North Downs, runs through them and north to the Thames, emerging at Deptford Creek. How did it, and other rivers such as the Wandle, Darent and Medway, come to flow through the North Downs? At one time it was thought that there were faults in the chalk which gave them a way through, but this has been discounted. The Weald is now low lying, but when tectonic plate movement, mainly caused by Africa colliding with Europe, raised not only the Alps but buckled strata in northern Europe, a Wealden ridge was formed. An underlying chalk stratum buckled with high ridges at the South and North Downs and a dip under the Weald, squeezing up the soft sedimentary rocks between them to form the Ridge. Fast flowing streams from the ridge soon eroded channels in the chalk on their way to the sea. The ridge has since been eroding away (reducing river flows). They are ancient rivers. London is over a layer of cretaceous chalk about 40m down, which in turn is over gault clay.
    [Show full text]
  • Outline • Background
    Outline • Background Case Study 1 • Landslide Debris (Dorset) Case Study 2 • Engineering NIR Stratigraphy (Hampshire) Case Study 3 • Weathering - London Clay (London) NIR Spectroscopy Background to NIR NIR Thermal Range Spectral Logging • Visible, NIR, SWIR Wavelengths (350-2500nm) • Spectral resolution 1nm • Measurement window 4-24 mm • Limited/no sample contact • No sample prep needed – (lab samples can be crushed) • Measurement time 0.05 secs Spectral Logging Sensitive to most minerals but especially clays Biggest applications: • Mining – mineral exploration • Heritage Conservation (as non contact) • Pharmaceuticals • Biscuits Typical XRD plot for London Clay Typical Lab Spectra • Sensitive to moisture, mineralogy, clay content, organics, plant health, particulate contaminants......... • Relate to weathering, water movement, vegetation growth Dark Clay Orange Sand 0 2500 nm 0 2500 nm Landslide Debris Particle Size Characterization Upper Group Lower Group Intermediate Group Particle Size Characterization • Possible to predict article composition from 2-3 wavelengths e.g. % clay =130.3-82.754*R(λ 2204 ) +937.388 R(λ 1411 ) Moisture Content Next Steps • Black Venn Study: debris flow mobility – does the mixing of debris flow materials relate to how mobile it is? Debris flow mechanics. • China Bailong Corridor (Zhouqu Debris Flow – Lanzhou Uni): properties of source materials with debris flow mobility. Current Research Projects: Engineering NIR Stratigraphy London Clay (Hampshire Basin) White Cliff Bay - Isle of Wight White Cliff Bay Geological
    [Show full text]
  • The Stratigraphical Framework for the Palaeogene Successions of the London Basin, UK
    The stratigraphical framework for the Palaeogene successions of the London Basin, UK Open Report OR/12/004 BRITISH GEOLOGICAL SURVEY OPEN REPORT OR/12/004 The National Grid and other Ordnance Survey data are used The stratigraphical framework for with the permission of the Controller of Her Majesty’s Stationery Office. the Palaeogene successions of the Licence No: 100017897/2012. London Basin, UK Key words Stratigraphy; Palaeogene; southern England; London Basin; Montrose Group; Lambeth Group; Thames Group; D T Aldiss Bracklesham Group. Front cover Borehole core from Borehole 404T, Jubilee Line Extension, showing pedogenically altered clays of the Lower Mottled Clay of the Reading Formation and glauconitic sands of the Upnor Formation. The white bands are calcrete, which form hard bands in this part of the Lambeth Group (Section 3.2.2.2 of this report) BGS image P581688 Bibliographical reference ALDISS, D T. 2012. The stratigraphical framework for the Palaeogene successions of the London Basin, UK. British Geological Survey Open Report, OR/12/004. 94pp. 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.
    [Show full text]
  • Geology of London, UK
    Proceedings of the Geologists’ Association 123 (2012) 22–45 Contents lists available at ScienceDirect Proceedings of the Geologists’ Association jo urnal homepage: www.elsevier.com/locate/pgeola Review paper Geology of London, UK a, b,c d e c Katherine R. Royse *, Mike de Freitas , William G. Burgess , John Cosgrove , Richard C. Ghail , f g h i j k Phil Gibbard , Chris King , Ursula Lawrence , Rory N. Mortimore , Hugh Owen , Jackie Skipper a British Geological Survey, Keyworth, Nottingham NG12 5GG, UK b First Steps Ltd, Unit 17 Hurlingham Studios, London SW6 3PA, UK c Department of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ, UK d Department of Earth Sciences, University College London, WC1E 6BT, UK e Department of Earth Science and Engineering, Imperial College London, London SW7 2AZ, UK f Cambridge Quaternary, Department of Geography, University of Cambridge, CB2 3EN, UK g 16A Park Road, Bridport, Dorset, UK h Crossrail Ltd. 25 Canada Square, Canary Wharf, London E14 5LQ, UK i University of Brighton & ChalkRock Ltd, 32 Prince Edwards Road, Lewes BN7 1BE, UK j Department of Palaeontology, The Natural History Museum, Cromwell Road, London SW7 5BD, UK k Geotechnical Consulting Group (GCG), 52A Cromwell Road, London SW7 5BE, UK A R T I C L E I N F O A B S T R A C T Article history: The population of London is around 7 million. The infrastructure to support this makes London one of the Received 25 February 2011 most intensively investigated areas of upper crust. However construction work in London continues to Received in revised form 5 July 2011 reveal the presence of unexpected ground conditions.
    [Show full text]
  • Crossrail Project: Machine-Driven Tunnels on the Elizabeth Line, London
    Civil Engineering Proceedings of the Institution of Civil Engineers Volume 170 Issue CE5 Civil Engineering 170 May 2017 Issue CE5 Pages 31–38 http://dx.doi.org/10.1680/jcien.16.00028 Crossrail project: machine-driven Paper 1600028 tunnels on the Elizabeth line, London Received 11/07/2016 Accepted 16/12/2016 Keywords: concrete structures/excavation/tunnels & King, Thomas and Stenning tunnelling ICE Publishing: All rights reserved Crossrail project: machine-driven tunnels on the Elizabeth line, London 1 Mike King BSc, CEng, MICE 3 Andy Stenning BSc, PhD, CPEng, MIEAust, MHKIE, MASCE Technical and Compliance Director - Tunnels, CH2M, London, UK Technical Director, Atkins Ltd, London, UK 2 Ivor Thomas BEng, LLB, CEng, FICE Tunnel Manager, BAM Nuttall, London, UK 1 2 3 The 42 km of tunnels constructed using soft-ground pressure-balance tunnel-boring machines for London’s new Elizabeth line were completed over a 3 year period. A single lining design solution was developed for all tunnels using a fully gasketed, steel-fibre-reinforced, concrete segmental lining suitable for use in all potential ground conditions anticipated along the alignment. The £14·8 billion Crossrail project faced many challenges, including dealing with significant quantities of different excavated material while minimising the environmental impact from transportation and disposal, minimising settlement effects and dealing with multiple tunnel-boring machine launches and receptions. This paper addresses how the issues were tackled and comments on the tunnel-boring machine design and the approach taken for survey control. Outline figures are also provided for the tunnelling rates. Finally, some conclusions and recommendations are made based on the observations and lessons learnt during the project.
    [Show full text]
  • Deoxygenated Gas Occurrences in the Lambeth Group of Central London
    1 Deoxygenated gas occurrences in the Lambeth Group of central 2 London 3 T. G. Newman1*, R. C. Ghail1 and J. A. Skipper2 4 1Department of Civil and Environmental Engineering, Imperial College London, London, SW7 5 2AZ, United Kingdom. *[email protected] (corresponding author) 6 2Geotechnical Consulting Group, 52A Cromwell Road, London, SW7 5BE, United Kingdom and 7 Department of Mineralogy, Natural History Museum, Cromwell Road, SW7 5BD 8 3,307 words (200 abstract; 3,120 main text) 9 3 tables, 12 figures, 39 references 10 Abbreviated Title: Deoxygenated Gas in London 11 Abstract: Deoxygenated gas poses a serious and life-threatening hazard (confined space hypoxia) for engineering 12 projects in London, particularly those in the Upnor Formation of the Lambeth Group. We review its causes and 13 postulate that it is induced by dewatering or positive pressure tunnelling bringing air into contact with these 14 sediments, causing oxidation. Subsequent resaturation results in pockets of deoxygenated gas. Drawdown of the 15 Lower Aquifer during the industrial growth of London brought air into contact with Lambeth Group sediments on a 16 regional scale. Its recharge has trapped and compressed deoxygenated gas beneath overlying impermeable clays. 17 Historically, the mineral glauconite has been blamed for these hazards, but it lacks potency as a reducing agent and 18 remains unaltered in many oxidised Lambeth Group sediments. Pyrite and organic carbon are both plausible but a 19 more potent agent is green rust, which readily and rapidly oxidises on contact with air, and which is only briefly 20 observed in fresh core samples.
    [Show full text]
  • Western Regional Group
    Western Regional Group The Latest Findings in the Lambeth Group Dr Jacqueline Skipper, Senior Consultant, GCG Tuesday 20th July 2021 Zoom Talk: opens at 6:15pm for 6:30pm Start The Western Regional Group is pleased to welcome Dr Jackie Skipper who will share her experience and knowledge of working in the Lambeth Group. The Lambeth Group is a relatively thin (c 18m thick in the London Basin, up to c 50m thick in the Hampshire Basin) group of very diverse sediments deposited in highly variable environments ranging from shallow marine to terrestrial. It is often highly coloured due to penecontemporaneous weathering, and can contain cemented layers, aggressive and deoxygenating minerals, and water bearing channels. It thus represents units of relatively high risk for sensitive engineering projects if poorly investigated and understood. The Lambeth Group is a good analogue for coastal- terrestrial sediments in sub-tropical to tropical environments in many other areas of the Earth such as Pleistocene-Holocene sediments in Australia, Malaysia and on the margins of the South China Sea generally. This talk will look at the current understanding of the stratigraphy of the Lambeth including several relatively new discovered sub units, and what risks these may represent. Dr Jackie Skipper is a Senior Consultant at the Geotechnical Consulting Group and has won the Geological Society Engineering Group Award in 2010 and the 18th Glossop Medal in 2010. Her PhD was in the stratigraphy of the Lambeth Group and her specialist areas include the Geology of London and SE England, complex ground conditions and Quaternary features worldwide, and the geology of desert sediments and environments However she is interested in all types of complex ground types and their relationship to risk in tunnelling, foundations and land stability.
    [Show full text]
  • Geological Long-Section
    Chief Engineer’s Group Crossrail Geological Long Section– Post- Construction Update Document Number: CRL1-GCG-C2-DWG-CRG03-50001 Document History: Revision: Date: Prepared by: Checked by: Authorised by: Reason for Issue: 1.0 April 2016 / This document contains proprietary information. No part of this document may be reproduced without prior written consent from the chief executive of Crossrail Ltd. Learn g Legacy Document Page 1 of 11 Document uncontrolled once printed. All controlled documents are saved on the CRL Document System © Crossrail Limited Unclassified Crossrail Geological Long Section - Post-Construction Update – April 2016 CRL1-GCG-C2-DWG-CRG03-50001, Rev 1.0 Contents 1 Introduction ............................................................................................................... 3 2 Notes on the Section ................................................................................................ 4 3 Key Findings .............................................................................................................. 5 4 REFERENCES ............................................................................................................ 8 APPENDICIES Appendix A: Report on distribution and geometry of sands in the Upper Lambeth Group of the Crossrail route Appendix B: Crossrail Canary Wharf Station Box- logging of Harwich Formation, 2010/2011 Document Legacy Learning Page 2 of 11 Document uncontrolled once printed. All controlled documents are saved on the CRL Document System © Crossrail Limited RESTRICTED
    [Show full text]
  • 1. the Geological Setting of the Coastal Fringes of West Sussex, Hampshire and the Isle of Wight
    CORE T HE Q UAT E R N A RY OF T HE S OLEN T B A S IN AND WMetadata,E st S U ss citationEX R AI andS ED similar B EACHE papersS at core.ac.uk Provided by NERC Open Research Archive 1. The geological setting of the coastal fringes of west Sussex, Hampshire and the Isle of Wight Peter M. Hopson Introduction This guide covers a significant part of southern Hampshire, a part of West Sussex and the Isle of Wight. The region is founded on Cretaceous and Palaeogene bedrock, the younger forming the final phase of sedimentation of the Hampshire Basin. The bedrock is covered by a thick and extensive succession of Quaternary superficial deposits subdivided into a number of units that represent a long Quaternary history as the landscape was denuded through numerous periglacial/ temperate clmatc cycles. Although the nter-relatonshps and ndvdual depostonal hstores of Quaternary stes are descrbed n more detal elsewhere n ths gude, the regional distribution of superficial deposits can be summarised as follows: early Quaternary residual deposits cap many of the hills and upper valley flanks on the Chalk Downs. An extensive spread of fluvial granular deposits of the proto-Solent Rver and ts trbutares are developed through a large part of the Plestocene and these pass laterally and vertcally to assocated marne and near-shore deposts n response to sea-level fluctuations. Finally, as sea-level rises, Holocene deposits, both fluviatile and marine were laid down as drowned valley fill, present day floodplains and as beach and near-shore deposits within the Solent and English Channel.
    [Show full text]
  • Geotechnical and Contamination Status Assessment Report
    GEOTECHNICAL AND ENVIRONMENTAL ENGINEERS Head Offi ce The Old Dairy Swanborough Farm Swanborough Lewes East Sussex BN7 3PF Telephone 0870 777 1574 SEAFORD HEAD SIXTH FORM STEYNE ROAD Fascimile SEAFORD 0870 777 1577 EAST SUSSEX Website GEOTECHNICAL AND www.AshdownSI.co.uk CONTAMINATION STATUS ASSESSMENT REPORT Email [email protected] Report No. LW24146 July 2013 Regional Offi ce Hertfordshire (Contact via Head Offi ce) Report prepared for the benefit of: Managing Director Kier Construction J.E.Bewick Longley House BSc MSc CEnv CEng MICE International Drive Southgate Avenue Company Secretary Crawley V.Bewick West Sussex BSc MSc FRSS RH10 6AQ Company Registration Number 242 6786 SEAFORD HEAD SIXTH FORM STEYNE ROAD SEAFORD EAST SUSSEX GEOTECHNICAL AND CONTAMINATION STATUS ASSESSMENT REPORT Report No. LW24146 July 2013 FACTUAL REPORT Prepared By: Approved By: Rebecca Jones John Bewick BSc FGS BSc MSc CEng CEnv MICE GEOTECHNICAL ASSESSMENT Prepared By: Approved By: Rebecca Jones John Bewick BSc FGS BSc MSc CEng CEnv MICE CONTAMINATION STATUS Prepared By: Approved By: Rebecca Jones John Bewick BSc FGS BSc MSc CEng CEnv MICE Report No: LW24146/contents SEAFORD HEAD SIXTH FORM STEYNE ROAD SEAFORD EAST SUSSEX GEOTECHNICAL AND CONTAMINATION (PHASE II) ASSESSMENT REPORT TABLE OF CONTENTS Page 1. INTRODUCTION 1 2. SITE DETAILS 2 2.1 Site Description 2 2.2 Expected Geology 2 2.3 Radon 3 2.4 Aquifer Status and Groundwater Source Protection Zones 3 2.5 Hydrology 4 3. GROUND INVESTIGATION 5 3.1 Introduction 5 3.2 Exploratory Holes 5 3.3 Sampling 5 3.4 In Situ Testing 5 3.5 Installations 6 3.6 Laboratory Testing 6 4.
    [Show full text]
  • The Geological Context and Evidence for Incipient Inversion of The
    The geological context and evidence for incipient inversion of the London Basin Contexte géologique et arguments en faveur de l’inversion naissante du bassin londonien R.C. Ghail*1, P.J. Mason2 , J.A. Skipper3 1 Department of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ, UK 2 Department of Earth Sciences & Engineering, Imperial College London, London SW7 2AZ, UK 3 Geotechnical Consulting Group, 52A Cromwell Road, London SW7 5BE, UK ABSTRACT A reappraisal of ground investigation data across London reveal that a range of unexpected ground conditions, encountered in engineering works since Victorian times, may result from the effects of ongoing inversion of the London Basin. Site investigation bore- hole data and the distribution of river terrace deposits of the Thames and its tributaries reveal a complex pattern of block movements, tilting and dextral transcurrent displacement. Significant displacements (~10 m) observed in Thames terrace gravels in borehole TQ38SE1565 at the Lower Lea Crossing, showing that movement has occurred within the last ~100 ka. Restraining bends on reactivated transcurrent faults may explain the occurrence of drift filled hollows, previously identified as fluvially scoured pingos, by faulting and upward migration of water on a flower structure under periglacial conditions. Mapping the location of these features constrains the location of active transcur- rent faults and so helps predict the likelihood of encountering hazardous ground conditions during tunnelling and ground engineering. RÉSUMÉ Une réévaluation des résultats provenant d’études de terrain à travers Londres a révélé une diversité de phénomènes géologiques inattendus. Rencontrés lors de travaux d’ingénierie depuis l’époque victorienne ils pourraient être causés par les suites de l’inversion du basin londonien en cours.
    [Show full text]
  • Lithological Characteristics of the Lambeth Group
    PAPER geotechnical properties. This is set in the context of the environment of deposition and also the post-depositional changes that altered these sediments, both of which are necessary to explain the observed .iI:~o oclica diversity. The measured geotechnical properties of the Lambeth Group are highly diverse, often too diverse to draw other than very conservative assumptions on engineering behaviour. This paper sets out to explain c >aracI:eris',ics why and how the sediments were formed and some of the complex processes that affected them. With this in mind, the measured values often obtained from a ground investigation can be appreciated and 'I, understood in a broader sense. Some brief recommendations are made o~ >e .agni )e', i for the treatment of sites where the Lambeth Group is encountered. The group has been increasingly encountered in major civil engineering schemes, for example, in the expansion of the east Thames corridor, the Jubilee Line Extension, the Docklands Light Railway I)roll ) Extension to Lewisham, the planned East London Line, CrossRail and the Channel Tunnel Rail Link. However, there have been few geological or integrated engineering geological studies of the By Darren Page, High-Point Rendel, London and Lambeth Group. Jackie Skipper, Natural History Museum, London. The paper forms a reference work for the forthcoming CIRIA report on Engineering Properties of UK Soils and Rocks: RP576 for the Lambeth Group co-authored by Darren Page with contributions by Jackie Skipper. nderlying the London Clay throughout south and south east Britain are a group of highly variable sediments belonging to the Stratlgraphlcal framework a Lambeth Group (formerly called the Woolwich and Reading Beds).
    [Show full text]