The Commission on Standardization of Laboratory and Field Tests on Rock was appointed in 1967. Subsequent to its first meeting in Madrid in October 1968, the Commission circulated a questionnaire to all members of the International Society for Rock Mechanics, the answers received clearly showing a general desire for standardized testing procedures. At a further meeting in Oslo in September 1969, tests were categorized and a priority for their standardization was agreed upon.

A work of this nature depends very heavily on one's fellow workers. We take this opportunity to thank those many people who have assisted us with advice, facilities, the loan of specimens, and helpful discussions over many years. We apologize to anyone who may have inadvertently been missed here. We especially would like to mention staff of the Natural History Museum, Dr С Patterson, Dr A. Milner, Dr M. K. Howarth, Dr P. D. Taylor, Dr A. Smith, Dr N. J. Morris and Mr R. J. Cleevely for allowing us to examine specimens in their care. Also, many thanks go to Dr B. M. Cox (British Geological Survey) and Dr J. K. Wright (Royal Holloway and Bedford College) for allowing us to use photographs. Professor J. H. Callomon (University College, London), Dr G. Chancellor (Peterborough City Museum), Mr Alan Dawn (Stamford), Dr D. T. Donovan (University College, London), Dr Tim Palmer (University of Wales at Aberystwyth), Dr Mike Barker (Portsmouth Polytechnic), Ms Liz Harper (Open University), Dr F. T. Fursich (University of Wurtzburg), and Dr R. G. Clements, Dr J. W. Faithfull and Mr R. Branson (Leicester University) all offered helpful advice. At Leicester Museum Dr M. A. Taylor and Dr A. Cruickshank offered helpful discussions on aspects of marine reptile paleobiology. We have also drawn heavily on data from Dr A. Williams and Dr I. St. J. Fisher, both of whom have made important contributions to our knowledge of the geochemistry of the Oxford Clay. Ms S. Button, Mr J. Taylor and Mr A. Lloyd assisted with diagrams. Mrs D. Туе and Mrs W. D. Hebden helped type manuscripts. Dr Alistair Crame (British Antarctic Survey) and Dr Ed. Jarzembowski acted on behalf of the Palaeontological Association.

With the decision to produce this guide book we very rapidly found that specimens of many of the fossils were not represented in our collections. To remedy this we undertook several field visits to enrich the collections at Leicester University and the Open University. We therefore thank the London Brick Company for permission to visit their brick pits, and in particular thank Mr P. Furr (LBC Bletchley), Mr Keith Morton (LBC Stewartby) and Mr A. Robinson (LBC Calvert) for their help.