Book geophysic

Field Geophysics
THIRD EDITION

John Milsom
University College London

Field Geophysics

The Geological Field Guide Series Basic Geological Mapping, Third edition John Barnes The Field Description of Metamorphic Rocks Norman Fry The Mapping of Geological Structures Ken McClay Field Geophysics, Third edition John Milsom The Field Description of Igneous Rocks Richard Thorpe & GeoffBrown Sedimentary Rocks in the Field, Second edition Maurice Tucker

Field Geophysics
THIRD EDITION

John Milsom
University College London

Copyright  2003 by Published 2003 by

John Milsom John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex PO19 8SQ, England Telephone (+44) 1243 779777

Email (for orders and customer service enquiries): cs-books@wiley.co.uk Visitour Home Page on www.wileyeurope.com or www.wiley.com First edition first published in 1989 by Open University Press, and Halsted Press (a division of John Wiley Inc.) in the USA, Canada and Latin America. Copyright  J. Milsom 1989. Second edition first published in 1996 by John Wiley & Sons Ltd. Copyright  1996 John Wiley & Sons Ltd. All Rights Reserved. No part of this publication may bereproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except under the terms of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London W1T 4LP, UK, without the permission in writing of the Publisher.Requests to the Publisher should be addressed to the Permissions Department, John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex PO19 8SQ, England, or emailed to permreq@wiley.co.uk, or faxed to (+44) 1243 770620. This publication is designed to provide accurate and authoritative information in regard to the subject matter covered. It is sold on the understanding that thePublisher is not engaged in rendering professional services. If professional advice or other expert assistance is required, the services of a competent professional should be sought. Other Wiley Editorial Offices John Wiley & Sons Inc., 111 River Street, Hoboken, NJ 07030, USA Jossey-Bass, 989 Market Street, San Francisco, CA 94103-1741, USA Wiley-VCH Verlag GmbH, Boschstr. 12, D-69469 Weinheim, GermanyJohn Wiley & Sons Australia Ltd, 33 Park Road, Milton, Queensland 4064, Australia John Wiley & Sons (Asia) Pte Ltd, 2 Clementi Loop #02-01, Jin Xing Distripark, Singapore 129809 John Wiley & Sons Canada Ltd, 22 Worcester Road, Etobicoke, Ontario, Canada M9W 1L1 Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronicbooks. Library of Congress Cataloging-in-Publication Data Milsom, John, 1939– Field geophysics / John Milsom.–3rd ed. p. cm. – (The geological field guide series) Includes bibliographical references and index. ISBN 0-470-84347-0 (alk. paper) 1. Prospecting–Geophysical methods. I. Title. II. Series. TN269 .F445 2002 622 .15–dc21 2002191039

British Library Cataloguing in Publication Data A cataloguerecord for this book is available from the British Library ISBN 0-470-84347-0 Typeset in 8.5/10.5pt Times by Laserwords Private Limited, Chennai, India Printed and bound in Great Britain by Antony Rowe Ltd, Chippenham, Wiltshire This book is printed on acid-free paper responsibly manufactured from sustainable forestry in which at least two trees are planted for each one used for paper production.Contents
Preface to the First Edition Preface to the Second Edition Preface to the Third Edition 1 Introduction 1.1 Fields 1.2 Geophysical Fieldwork 1.3 Geophysical Data 1.4 Bases and Base Networks 1.5 Global Positioning Satellites 2 Gravity Method 2.1 Physical Basis of the Gravity Method 2.2 Gravity Meters 2.3 Gravity Reductions 2.4 Gravity Surveys 2.5 Field Interpretation 3 Magnetic...