The climate of the Earth has undergone many changes and for those times when geologic data are widespread and abundant the Mesozoic appears to have been one of the warmest intervals. This was a time during which the single continent Pangea disintegrated into continental units similar to those of today, a time when there were no significant polar ice caps and sea level was generally much higher than at the present time, and a time when dinosaurs apparently dominated terrestrial faunas and the flowering plants evolved. Understanding this alien world, ancestral to ours, is intrinsically interesting, intellectually challenging, and offers opportunities for more effective targeting of sites where commercially important geological resources may be found. It also provides critical insights into the operation of coupled Earth systems (biospheric, atmospheric, hydrospheric and geospheric) under extreme 'greenhouse' conditions, and therefore may have relevance to possible future global change. Our intention in organizing this Discussion Meeting was to bring together those who gather and interpret geologic data with those who model global climates from first principles. The community of workers who study the Quaternary have made significant advances by integrating and comparing palaeodata and climate model experiments. Although we have focused not on the Quaternary 'icehouse' but on the Mesozoic 'hothouse' climate we are well aware that approaches used in the study of the Quaternary may have relevance to earlier times.

Reservoirs generally consist of sandstones or carbonates exhibiting heterogeneities caused by a wide range of factors. Some of these formed depositionally (e.g. as channels, palaeosols, clay seams or salts), others may be diagenetic in origin (e.g. carbonate or silica cemented zones, authigenic clays, karstic surfaces). The severity with which diagenesis affects rock systems results from the interplay between the diagenetic process itself and the timescale over which it operated. The book provides a wide-ranging overview of diagenetic processes and responses in calcareous, argillaceous, arenaceous and carbon-rich (microbial and organic) sedimentary systems. It introduces diagenetic concepts, reviews existing knowledge, and shows how existing qualitative approaches might be developed in more quantitative ways. Several chapters consider mass balance calculations and the temporal and spatial aspects of diagenetic processes. It is unique, as a textbook, in providing such a breadth of diagenetic subject range and such depth of coverage in each topic. It provides a source reference for advanced students and professionals active in reservoir and aquifer studies.

Reservoirs generally consist of sandstones or carbonates exhibiting heterogeneities caused by a wide range of factors. Some of these formed depositionally (e.g. as channels, palaeosols, clay seams or salts), others may be diagenetic in origin (e.g. carbonate or silica cemented zones, authigenic clays, karstic surfaces). The severity with which diagenesis affects rock systems results from the interplay between the diagenetic process itself and the timescale over which it operated. The book provides a wide-ranging overview of diagenetic processes and responses in calcareous, argillaceous, arenaceous and carbon-rich (microbial and organic) sedimentary systems. It introduces diagenetic concepts, reviews existing knowledge, and shows how existing qualitative approaches might be developed in more quantitative ways. Several chapters consider mass balance calculations and the temporal and spatial aspects of diagenetic processes. It is unique, as a textbook, in providing such a breadth of diagenetic subject range and such depth of coverage in each topic. It provides a source reference for advanced students and professionals active in reservoir and aquifer studies.

The climate of the Earth has undergone many changes and for those times when geologic data are widespread and abundant the Mesozoic appears to have been one of the warmest intervals. This was a time during which the single continent Pangea disintegrated into continental units similar to those of today, a time when there were no significant polar ice caps and sea level was generally much higher than at the present time, and a time when dinosaurs apparently dominated terrestrial faunas and the flowering plants evolved. Understanding this alien world, ancestral to ours, is intrinsically interesting, intellectually challenging, and offers opportunities for more effective targeting of sites where commercially important geological resources may be found. It also provides critical insights into the operation of coupled Earth systems (biospheric, atmospheric, hydrospheric and geospheric) under extreme 'greenhouse' conditions, and therefore may have relevance to possible future global change. Our intention in organizing this Discussion Meeting was to bring together those who gather and interpret geologic data with those who model global climates from first principles. The community of workers who study the Quaternary have made significant advances by integrating and comparing palaeodata and climate model experiments. Although we have focused not on the Quaternary 'icehouse' but on the Mesozoic 'hothouse' climate we are well aware that approaches used in the study of the Quaternary may have relevance to earlier times.

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.