The Solid Earth: an Introduction to Global Geophysics, Second Edition C
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Cambridge University Press 0521584094 - The Solid Earth: An Introduction to Global Geophysics, Second Edition C. M. R. Fowler Frontmatter More information The Solid Earth From the citation for the Prestwich Medal of the Geological Society, 1996 (awarded for the contribution made by The Solid Earth to geophysics teaching and research) by the then President Professor R. S. J. Sparks F.R.S. The Prestwich Medal is given for major contributions to earth science, and provides an opportunity for the Society to recognise achievements in areas that can lie outside the terms of reference of its other awards. This year, the Prestwich Medal has been given to Mary Fowler for the contribution of her book, The Solid Earth, which has had an enormous impact. The book has been acclaimed by today’s leading geophysicists. There is consensus that, although there are many books covering various aspects of geophysics, there are only a small number that can be seen as landmarks in the subject. Mary’s book has been compared to Jeffreys’s The Earth and Holmes’s Physical Geology. The Solid Earth is recognised by her peers as a monumental contribution. In this book she displays a wide knowledge of a very broad range of geological and geophysical topics at a very high level. The book provides a balanced and thoroughly researched account which is accessible to undergraduates as well as to active researchers. The book has been described as one of the outstanding texts in modern earth sciences. (Geoscientist, Geological Society, 1996, Vol. 6, No. 5, p. 24.) © Cambridge University Press www.cambridge.org Cambridge University Press 0521584094 - The Solid Earth: An Introduction to Global Geophysics, Second Edition C. M. R. Fowler Frontmatter More information The Solid Earth An Introduction to Global Geophysics Second Edition C. M. R. Fowler Royal Holloway University of London © Cambridge University Press www.cambridge.org Cambridge University Press 0521584094 - The Solid Earth: An Introduction to Global Geophysics, Second Edition C. M. R. Fowler Frontmatter More information published by the press syndicate of the university of cambridge The Pitt Building, Trumpington Street, Cambridge, United Kingdom cambridge university press The Edinburgh Building, Cambridge, CB2 2RU, UK 40 West 20th Street, New York, NY 10011–4211, USA 477 Williamstown Road, Port Melbourne, VIC 3207, Australia Ruiz de Alarc´on13, 28014 Madrid, Spain Dock House, The Waterfront, Cape Town 8001, South Africa http://www.cambridge.org C Cambridge University Press 2005 This book is in copyright. Subject to statutory exception and to the provisions of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. First published 2005 Printed in the United Kingdom at the University Press, Cambridge Typefaces Times NR 10/13 pt. and Universe System LATEX2ε [tb] A catalogue record for this book is available from the British Library Library of Congress Cataloguing in Publication data Fowler, C. M. R. The solid earth: an introduction to global geophysics / C. M. R. Fowler. – 2nd ed. p. cm. Includes bibliographical references and index. ISBN 0 521 58409 4 (hardback) – ISBN 0 521 89307 0 (paperback) 1. Geophysics. 2. Earth. I. Title. QC806.F625 2004 550 – dc22 2003065424 ISBN 0 521 58409 4 hardback ISBN 0 521 89307 0 paperback © Cambridge University Press www.cambridge.org Cambridge University Press 0521584094 - The Solid Earth: An Introduction to Global Geophysics, Second Edition C. M. R. Fowler Frontmatter More information TO MY FAMILY Magna opera domini exoquisita in omnes voluntates ejus. The works of the Lord are great, sought out of all them that have pleasure therein. Psalm 111.2: at the entrance to the old Cavendish Laboratories, Cambridge. © Cambridge University Press www.cambridge.org Cambridge University Press 0521584094 - The Solid Earth: An Introduction to Global Geophysics, Second Edition C. M. R. Fowler Frontmatter More information Contents Preface to the first edition page xi Preface to the second edition xv Acknowledgements to the first edition xvi Acknowledgements to the second edition xviii 1 Introduction 1 References and bibliography 3 2 Tectonics on a sphere: the geometry of plate tectonics 5 2.1 Plate tectonics 5 2.2 A flat Earth 11 2.3 Rotation vectors and rotation poles 14 2.4 Present-day plate motions 15 2.5 Plate boundaries can change with time 24 2.6 Triple junctions 26 2.7 Absolute plate motions 32 Problems 37 References and bibliography 40 3 Past plate motions 43 3.1 The role of the Earth’s magnetic field 43 3.2 Dating the oceanic plates 54 3.3 Reconstruction of past plate motions 67 Problems 93 References and bibliography 94 4 Seismology Measuring the interior 100 4.1 Waves through the Earth 100 4.2 Earthquake seismology 111 4.3 Refraction seismology 140 4.4 Reflection seismology 157 Problems 178 References and bibliography 186 vii © Cambridge University Press www.cambridge.org Cambridge University Press 0521584094 - The Solid Earth: An Introduction to Global Geophysics, Second Edition C. M. R. Fowler Frontmatter More information viii Contents 5 Gravity 193 5.1 Introduction 193 5.2 Gravitational potential and acceleration 193 5.3 Gravity of the Earth 196 5.4 The shape of the Earth 198 5.5 Gravity anomalies 202 5.6 Observed gravity and geoid anomalies 213 5.7 Flexure of the lithosphere and the viscosity of the mantle 218 Problems 228 References and bibliography 230 6 Geochronology 233 6.1 Introduction 233 6.2 General theory 234 6.3 Rubidium–strontium 244 6.4 Uranium–lead 247 6.5 Thorium–lead 249 6.6 Potassium–argon 251 6.7 Argon–argon 252 6.8 Samarium–neodymium 254 6.9 Fission-track dating 258 6.10 The age of the Earth 262 Problems 265 References and bibliography 267 7 Heat 269 7.1 Introduction 269 7.2 Conductive heat flow 270 7.3 Calculation of simple geotherms 275 7.4 Worldwide heat flow: total heat loss from the Earth 285 7.5 Oceanic heat flow 288 7.6 Continental heat flow 298 7.7 The adiabat and melting in the mantle 303 7.8 Metamorphism: geotherms in the continental crust 308 Problems 321 References and bibliography 323 8 The deep interior of the Earth 326 8.1 The internal structure of the Earth 326 8.2 Convection in the mantle 353 8.3 The core 371 References and bibliography 381 © Cambridge University Press www.cambridge.org Cambridge University Press 0521584094 - The Solid Earth: An Introduction to Global Geophysics, Second Edition C. M. R. Fowler Frontmatter More information Contents ix 9 The oceanic lithosphere: ridges, transforms, trenches and oceanic islands 391 9.1 Introduction 391 9.2 The oceanic lithosphere 397 9.3 The deep structure of mid-ocean ridges 409 9.4 The shallow structure of mid-ocean ridges 417 9.5 Transform faults 440 9.6 Subduction zones 458 9.7 Oceanic islands 487 Problems 492 References and bibliography 493 10 The continental lithosphere 509 10.1 Introduction 509 10.2 The growth of continents 517 10.3 Sedimentary basins and continental margins 557 10.4 Continental rift zones 584 10.5 The Archaean 595 Problems 601 References and bibliography 602 Appendix 1 Scalars, vectors and differential operators 615 Appendix 2 Theory of elasticity and elastic waves 620 Appendix 3 Geometry of ray paths and inversion of earthquake body-wave time–distance curves 630 Appendix 4 The least-squares method 636 Appendix 5 The error function 638 Appendix 6 Units and symbols 640 Appendix 7 Numerical data 648 Appendix 8 The IASP91 Earth model 650 Appendix 9 The Preliminary Reference Earth Model, isotropic version – PREM 651 Appendix 10 The Modified Mercalli Intensity Scale (abridged version) 654 Glossary 655 Index 666 The colour plates are situated between pages 398 and 399. © Cambridge University Press www.cambridge.org Cambridge University Press 0521584094 - The Solid Earth: An Introduction to Global Geophysics, Second Edition C. M. R. Fowler Frontmatter More information Preface to the first edition Geophysics is a diverse science. At its best it has the rigour of physics and the vigour of geology. Its subject is the Earth. How does the Earth work? What is its composition? How has it changed? Thirty years ago many of the answers to these questions were uncertain. We knew the gross structure of our planet and that earthquakes occurred, volcanoes erupted and high mountains existed, but we did not understand why. Today we have a general knowledge of the workings of the planet, although there is still much to be discovered. My aim in writing this book was to convey in a fairly elementary way what we know of the structure and dynamics of the solid Earth. The fabric of geophysics has changed dramatically in the decades since the discovery of plate tectonics. The book places a strong emphasis on geophysical research since the initial formulation of plate theory, and the discussion centres on the crust and upper mantle. It also outlines the recent increases in our knowledge of the planet’s deeper interior. To whom is this book addressed? It is designed to serve as an introduction to geophysics for senior undergraduates in geology or physics and for graduate students in either subject who need to learn the elements of geophysics. My hope is that the book will give them a fairly comprehensive basis on which to build an understanding of the solid Earth. Part of the challenge in writing a geophysics text is to make the book accessible to both types of student. For instance, some students enter the study of geophysics from a background in the Earth sciences, others from physics or mathematics: only a few enroll directly in geophysics programmes.