The study of paleocurrents, since 1963, is now a very routine part of sedimentology, and more and more such studies are finding use in other fields. Thus it seemed appropriate for us to review post-1963 developments and present them in a compact manner for the interested reader. Instead of rewriting a second edition, which thirteen years later we would organize in a completely dif ferent way, we have brought each chapter up to date with new material up to 1976. A new update supplement has in this edition been inserted after each one of the original chapters. We have stayed close to the original theme of paleocurrents-how to measure them and how to use them to solve geological problems ranging in scale from the hand specimen to the sedimentary basin and beyond. We have used many annotated references and tables to help pre sent this information to the reader. The reader will note that we have cited a few 1962 references - pUblications that appeared too late to be cited in the original 1963 edition. A few times we have also cited a reference which was included in the first edition. These are marked with an asterisk and hence do not appear in the new lists of references. We have been aided by many. In Cincinnati, WANDA OSBORNE and JEAN CARROL did typing and RICHARD SPOHN, the University's geological librarian, was very helpful in obtaining many references to the literature.

In the past, interest in sedimentary structures has arisen mainly from the expectation that these features might be a guide to the environment of depo sition. But many sedimentary structures have also proved useful in determining stratigraphic order in nonfossiliferous, steeply inclined beds especially in Pre cambrian terranes. As the sequence problem has been reviewed at length by Shrock, it seemed to us, therefore, that the time is now ripe for a new look at sedimentary structures, not with respect to "top and bottom," but with reference to "fore and aft. " Much of the present-day interest in these structures stems from their usefulness in mapping of paleocurrents. A stage has been reached where there is need for a work which assembles, digests, and organizes our collective knowledge of the usefulness of directional properties of sediments and their application to basin analysis. This we have attempted to write. The desirability and need for such a book occurred to both of us independently. Upon discovering our mutual interest, we decided that a better book could be written by collaboration. Fortunately this collaboration became a reality because of support by the Guggenheim Foundation of one of us and the cooperation and support of The Johns Hopkins University of both of us. We acknowledge with thanks this indispensable aid.

This book is intended as a practical handbook for those engaged in the task of analyzing the paleogeographic evolution of ancient sedimentary basins. The science of stratigraphy and sedimentology is central to such endeavors, but although several excellent textbooks on sedimentology have appeared in recent years little has been written about modern stratigraphic methods. Sedimentology textbooks tend to take a theoretical approach, building from physical and chemical theory and studies of mod ern environments. It is commonly difficult to apply this information to practical problems in ancient rocks, and very little guidance is given on methods of observation, mapping and interpretation. In this book theory is downplayed and the emphasis is on what a geologist can actually see in outcrops, well records, and cores, and what can be ob tained using geophysical techniques. A new approach is taken to stratigraphy, which attempts to explain the genesis of lithostratigraphic units and to de-emphasize the importance of formal description and nam ing. There are also sections explaining principles of facies analysis, basin mapping methods, depositional systems, and the study of basin thermal history, so important to the genesis of fuels and minerals. Lastly, an at tempt is made to tie everything together by considering basins in the con text of plate tectonics and eustatic sea level changes.

Review of the second edition "For geologists and geophysicists studying sedimentary fill of basins, this volume is a valuable addition to their shelves. The book is packed with informationincludes numerous lists of references, and is up-to-date. As a source volume, this book is second to none. It is clear and well organized." GEOPHYSICS

Turbidite sedimentation of ancient orogenic belts is considered closely related to that of marginal flood-dominated fluvio-deltaic systems. These notes provide criteria that can be used for the description and interpretation of ancient turbidite systems exposed in thrust and fold belts.