INSTITUTE OF GEOLOGICAL SCIENCES Mineral Assessment Report 55 Natural Environment Research Council I]The sandand gravel Stowmarket I Y resources of the country TM15 3Coddenham Ufford around Ipswich, Suffolk TM25 1 Description of I :25 000 resource sheet TM 14 TM04 e Hadleigh <StratfordSt Mary R. Allender and S. E. Hollyer 0Crown copyright 1981 ISBN 0 11884116 5* London Her Majesty'sStationery Office 198 I PREFACE The first twelve reports on the assessmentof British National resourcesof many industrial mineralsmay sand and gravel resources appearedin the Report series seem so large that stocktaking appears unnecessary, but of the Instituteof Geological Sciencesas a subseries. the demand for minerals and for landall purposes for is Report 13 and subsequent reports appearas Mineral intensifying andit has become increasingly clearin Assessment Reportsof the Institute. recent years that regional assessmentsof the resources of these minerals should be undertaken. The publication Details of published reports appear at the ofend this of information about the quantity and qualityof deposits Report. over large areasis intended to provide a comprehensive Any enquiries concerning this reportmay be addressed factual background againstwhich planning decisions can to Head, Industrial Minerals Assessment Unit, Institutebe made. of Geological Sciences, Keyworth, Nottingham Sand and gravel, considered togetheras naturally NG12 5GG. occurring aggregate,was selected as the bulk mineral demanding the most urgent attention, initiallyin the south-east of England, where abouthalf the national output is won and very few sourcesof alternative aggregates are available.Following a short feasibility project, initiated in1966 by the Ministry of Land and Natural Resources, the Industrial Minerals Assessment Unit (formerly the Mineral Assessment Unit) began systematic surveys in1968. The workis now being financed by the Departmentof the Environment andis being undertaken with the cooperationof the Sand and Gravel Associationof Great Britain. This report describes the resourcesof sand andgravel of 100 km2of country aroundIpswich, Suffolk, shownon the accompanying1:25 O00 resource map. Thesurvey was conductedby Dr R. Allender,Mr S. E. Hollyer, Mr S. J. Booth and MrS. Machin in 1969-71. Mr M. R. Clarke, Mr M.P. Hawkins, MrJ. W. Merritt and MrE. J. Raynor have helpedwith the preparationof this report. The workis based on a1:63 360 scale geological survey published in1881-1883, and reprinted (with minor corrections) in1927 as the New Series one-inch Sheet 207. Mr J. W. Gardner, CBE (Land Agent),was responsible for negotiatingaccess to land for drilling. The ready cooperationof landowners and tenantsis gratefully acknowledged. G. M. Brown Director Institute of Geological Sciences Exhibition Road London SW7 2DE December 1979 ii CONTENTS MAP The sand and gravel resourcesof the country around summary 1 Ipswich, Suffolk in pocket Introduction 1 Descriptionof the district 2 TABLES General 2 1 Geological classification of deposits 3 Topography 2 2 The mean gradingof upper and lower partsof the Geology 2 RedCrag 8 Composition of the sand and gravel 7 3 The sand and gravel resourcesof sheet TM 14 10 Themap 8 4 Classification of gravel, sand and fines 17 Results 10 Notes on resource blocks 10 Appendix A: Field and laboratory procedures I4 Appendix B: Statistical procedure 14 Appendix C: Classification and descriptionof sand andgravel 1 5 Appendix D: Explanation of the borehole records 18 Appendix E: List of boreholes usedin the assessmentof resources 20 Appendix F: Industrial Minerals Assessment Unit borehole records 21 Appendix G:List of workings 72 Appendix H: Conversion table-metres to feet 73 References 74 FIGURES Location of the survey area and its relation to the adjacent survey areas(TM 13,23 and24) for which reports have been published 2 Generalised sub-drift (solid)geology 4 The thicknessesof the Red Crag provedin 24 assessmentboreholes 5 The main areasof mineral and their relationship to the resource block boundaries 6 North to south longitudinal sectionof the northern part of the Gipping Valley 7 Mean particle-size distributions for the mineralin resource blocks A to E 9 Comparison of the particle-size distributionsof the mineral deposits in blocks A to E 1 1 Example of resource block assessment: calculation andresults 15 Example of resource block assessment: mapof fictitious block 15 10 Diagram to show the descriptive categories usedin the classification of sand and gravel 17 ... 111 The sand and gravel resourcesof the country around Ipswich, Suffolk Description of 1:25 000 resource sheet TM 14 R.ALLENDER and S. E. HOLLYER SUMMARY INTRODUCTION The assessment of the sand and gravel resourcesin the The survey is concerned with the estimationof resources, Ipswich areais based upon thegeological maps of the which include deposits that are not currently exploitable Institute of Geological Sciences, pre-existing borehole but have a foreseeable use, rather than reserves,which information and68 boreholes drilled for the Industrial canonly be assessedin the light of current, locally Minerals Assessment Unit. prevailing, economic considerations. Clearly, both the All deposits in the area that might be potentially economic and the social factors used to decide whether a workable for sand andgravel have been investigated and deposit may be workable in the future cannot be pre- a simple statistical method has beenused to estimate dicted; they are likely to change with time. Deposits their volume. The reliabilityof the volume estimatesis not currently economically workablemay be exploited given at the symmetrical95 per cent probability level. asdemand increases, as highergrade or alternative The 1:25 000 map is divided into five resource blocks materialsbecome scarce, or as improved processing containing between 6.6 and 12.1 km2of potentially techniques areapplied to them. The improvedknowledge workable sand and gravel. For eachblock the geology of of the mainphysical propertiesof the resource and their the depositsis described and the mineral-bearing area, variability which this survey seeks to provide, will add the mean thicknessof overburden and mineral and the significantly to the factual background against which mean gradingsarG stated. Detailed borehole data are planning policies canbe decided (Archer, 1969; Thurrell, also given. The geology, the positionof the boreholes 1971; Harris and others,1974). and the outlinesof the resourceblocks are shown on the The survey provides information at the ‘indicated’ accompanying mapTM 14. level “for which tonnage and grade are computed partly from specific measurements, samples or production data and partly from projection for a reasonable distance on geological evidence. The sites available for inspection, measurement, and sampling are toowidely or otherwise inappropriately spaced to permit the mineralbodies to be outlined completely or the grade established through- out” (Bureau of Mines and Geological Survey, 1948, p. 15). It follows that the whereaboutsof reserves must still be established and their size and quality proved by the customary detailedexploration andevaluation undertaken by the industry. However, the information providedby this survey should assist in the selection of the best targets for such further work. The following arbitrary physical criteria have been adopted: a The deposit should average at least1 m in thickness. b The ratio of overburden to sand and gravel should be no more than3: 1. c The proportion of fines (particles passing the No. 240 mesh BS sieve, about &mm) should not Note exceed 40 per cent. All National Grid referencesin this reportlie withinthe d The deposit should lie within 25 m of the surface, 1:25OOO sheet TM 14. this being taken as thelikely maximum working depth under most circumstances.follows It from the second criterion that boreholes are drilled no Bibliographical reference deeper than18 m if no sand andgravel has been ALLENDER, R. and HOLLYER,S. E. 1981. The sand proved. and gravel resourcesof the country aroundIpswich, A deposit of sand and gravel which broadly meets Suffolk. Miner. Assess. Rep. Inst. Geol. Sci., No. 55. these criteriais regarded as ‘potentially workable’ andis described andassessed as ‘mineral’ in thisreport. As the Authors assessment is at the indicated level, parts of such a R. Allender, BSc, PhD, formerly at deposit may notsatisfy allthe criteria. Institute of Geological Sciences, London For the particular needs of assessing sand and gravel S. E. Hollyer, BSc, Instituteof Geological Sciences, resources, a grain-size classification based on the geo- 27 Gorst Road, LondonNWlO metric scalehmm, imm, lmm, 4mm, 16mmhas been. 1 Figure 1 Location of the survey area and its relation to the adjacentsurvey areas (TM 13,23 and 24) for which reports have been published adopted. The boundaries between fines (that is,clay the TOPOGRAPHY and silt fractions) and sand, and between sand gravel and The main feature of the area is the valley of the River grade material, areplaced at mm and 4 mm respectively Gipping, whichflows southwards from Claydon through (see AppendixC) . Bramford and Sproughton, before meandering south- Thevolume and other characteristics are assessed eastwards through Ipswich. To the south of Ipswich within resource blocks, eachof which, ideally, contains docks, this river is called the River Orwell and flows approximately 10 km2 of sand and gravel.No account is south-eastwards in a broad tidal estuary (Figure 1). The taken of any factors, for example,