K.R. McClay Department of Geology, Royal Holloway and Bedford New College, University of London, Egham, Surrey, England TW20 OEX. Since the first Thrust and Nappe Tectonics Conference in London in 1979 (McClay & Price 1981), and the Toulouse Meeting on Thrusting and Deformation in 1984 (Platt et al. 1986) there have been considerable advances in the study of thrust systems incorporating new field observations, conceptual models, mechanical models, analogue and numerical simulations, together with geophysical studies of thrust belts. Thrust Tectonics 1990 was an International Conference convened by the editor and held at Royal Holloway and Bedford New College, University of London, Egham Surrey, from April 4th until April 7th 1990. There were one hundred and seventy participants from all continents except South America. The conference was generously sponsored by Brasoil U.K. Limited, BP Exploration, Chevron U.K. Limited, Clyde Petroleum, Enterprise Oil, Esso Exploration and Production UK Limited, and Shell U.K. Exploration and Production. One hundred and five contributions were presented at the meeting, - seventy six oral presentations (together with poster displays) and an additional twenty nine posters without oral presentation (McClay 1990, conference abstract volume).

A knowledge of structural geology is fundamental to understanding the processes by which the earth's crust has evolved. It is a subject of fundamental importance to students of geology, experienced field geologists and academic researchers as well as to petroleum and mining engineers. In contrast to many structural textbooks which dwell upon geometrical descriptions of geological structures, this book emphasises mechanical principles and the way in which they can be used to understand how and why a wide range of geological structures develop. Structures on all scales are considered but the emphasis of the book is on those that can be seen on the scale of hand specimen or outcrop. Drawing on their considerable teaching experience the authors present a coherent and lucid analysis of geological structures which will be welcomed by a wide variety of earth scientists.

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Nappes and overthrusts are the mosl representative geological structures in mountain chains. The issue of their emplacement mechanisms and of the driving force of these displacements is a major problem in tectonics which interests, for near to a century now and not without harsh controversies, a significant proportion of structural geologists and geoscientists who work in the field of rock mechanics. This book attempts to give a clear and didactic synthesis of the current knowledge of the concept of thrusting, principally by tackling two approaches, mechanics and kinematics, which have proposed some solutions to this problem. At first (Chapter I), the notions of thrusting are defined, with the most recent terminology and the most important geometric aspects. This introduction to the geometry of thrusts is logically followed by the presentation of their problem; the issue of the emplacement mechanisms (Chapter 2). Let us note in passing that the formulation of the concept and the presentation of its problem are associated historically, which justifies presenting them in the historical framework of this discovery before tackling the different solutions and mechanical hypotheses. These are detailed in Chapter 3 by following a chronological progression, and emphasising the divergences and oppositions between different models so as to cover them fully. The chapter on the kinematics (Chapter 4) then returns to the type of data which can be collected in the field, by clarifying the relationships between displacement and internal strain.