The topic of sediment diagenesis is of fundamental importance to industry in the evaluation of hydrocarbon and water reservoir rocks. Detailed knowledge of the diagenetic textures, fabrics, and minerals, and a prediction of the regional diagenetic response, partly controls hydrocarbon recovery programmes. In other words, knowledge of the diagenesis can aid (or even control) conservation policy. Similarly, facies and diagenetic trends w.ithin basins can influence exploration policy. This volume incorporates the majority of the principal contributions given to the NATO Advanced Study Institute held in the University of Reading, U.K., from July 12th-25th, 1981, at which the major themes of carbonate and terrigenous clastic sediments were treated sequentially from deposition to deep burial. Eighty selected scientists from twelve NATO and three other countries participated in the Institute. The keynote addresses which acted as the touchstones for discussion are presented here in the expectation that they will stimulate a still wider audience. We gratefully acknowledge the award of a grant from the Scientific Affairs Division of NATO to run the Institute, and also the cooperation of the University of Reading. Mrs. D. M. Powell helped in many ways with the organisation, and also retyped the entire manuscript of this book. A. Parker B. lv. Sellwood vii FACIES, SEQUENCES AND SAND-BODIES OF THE PRINCIPAL CLASTIC DEPOSITIONAL ENVIRONMENTS T.Elliott Department of Geology University College of Swansea Singleton Park, Swansea SA 2 8PP Wales, U.K.