ENCYCLOPEDIA of GEOMAGNETISM AND PALEOMAGNETISM Encyclopedia of Earth Sciences Series ENCYCLOPEDIA OF GEOMAGNETISM AND PALEOMAGNETISM Volume Editors David Gubbins is Research Professor of Earth Sciences in the School of Earth and Environment, University of Leeds, UK. He did his PhD on geomagnetic dynamos in Cambridge, supervised by Sir Edward Bullard and has worked in the USA, and in Cambridge before moving to Leeds in 1989. His work has included dynamo theory and its connection with the Earth's thermal history, modeling the Earth's magnetic field from historical measurements, and recently the interpretation of paleomagnetic data. He is a fellow of the Royal Society and has been awarded the gold medal of the Royal Astronomical Society and the John Adam Fleming Medal of the American Geophysical Union for original research and leadership in geomagnetism. Emilio Herrero-Bervera is Research Professor of Geophysics at the School of Ocean and Earth Science and Technology (SOEST) within the Hawaii Institute of Geophysics and Planetology (HIGP) of the University of Hawaii at Manoa, where he is the head of the Paleomagnetics and Petrofabrics Laboratory. During his career he has published over 90 papers in professional journals including Nature, JGR, EPSL, JVGR. He has worked in such diverse fields as volcanology, sedimentology, plate tectonics, and has done field work on five continents. Aim of the Series The Encyclopedia of Earth Sciences Series provides comprehensive and authoritative coverage of all the main areas in the earth sciences. Each volume comprises a focused and carefully chosen collection of contributions from leading names in the subject, with copious illustrations and reference lists. These books represent one of the world's leading resources for the Earth sciences community. Previous volumes are being updated and new works published so that the volumes will continue to be essential reading for all professional Earth scientists, geologists, geophysicists, climatologists, and oceanographers as well as for teachers and students. See the back of this volume for a current list of titles in the Encyclopedia of Earth Sciences Series. Go to http://www.springerlink.com/reference- works/ to visit the “Earth Sciences Series” on-line. About the Editors Professor Rhodes W. Fairbridge{ has edited 24 encyclopedias in the Earth Sciences Series. During his career he has worked as a petroleum geologist in the Middle East, been a World War II intelligence officer in the SW Pacific, and led expeditions to the Sahara, Arctic Canada, Arctic Scandinavia, Brazil, and New Guinea. He was Emeritus Professor of Geology at Columbia University and was affiliated with the Goddard Institute for Space Studies. Professor Michael Rampino has published more than 100 papers in professional journals including Science, Nature, and Scientific American. He has worked in such diverse fields as volcanology, planetary science, sedimentology, and climate studies, and has done field work on six continents. He is currently Associate Professor of Earth and Environmental Sciences at New York University and a consultant at NASA's Goddard Institute for Space Studies. ENCYCLOPEDIA OF EARTH SCIENCES SERIES ENCYCLOPEDIA of GEOMAGNETISM AND PALEOMAGNETISM edited by DAVID GUBBINS University of Leeds and EMILIO HERRERO- BERVERA University of Hawaii at Manoa A C.I.P. Catalogue record for this book is available from the Library of Congress. ISBN-13: 978-1-4020-3992-8 This publication is available also as Electronic publication under ISBN 978-1-4020-4423-6 and Print and electronic bundle under ISBN 978-1-4020-4866-1 Published by Springer PO Box 17, 3300 AA Dordrecht, The Netherlands Printed on acid‐free paper Cover photo: Part of “A Digital Age Map of the Ocean Floor”, by Mueller, R.D., Roest, W.R., Royer, J.‐Y., Gahagan, L.M., and Sclater, J.G., SIO Reference Series 93-30, Scripps Institution of Oceanography (map downloaded courtesy of NGDC). Every effort has been made to contact the copyright holders of the figures and tables which have been reproduced from other sources. Anyone who has not been properly credited is requested to contact the publishers, so that due acknowledgment may be made in subsequent editions. All Rights Reserved © 2007 Springer No part of this work may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without written permission from the Publisher, with the exception of any material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work. Dedication Jack A. Jacobs (1916–2003) This encyclopedia is dedicated to the memory of Jack Jacobs. He made Geomagnetism intended to replace Chapman & Bartels’ work of contributions across the whole spectrum of geomagnetism and the same name, cover the field. For this encyclopedia he completed paleomagnetism throughout a long and productive career. His books articles for both editors, on disc dynamo and geomagnetic excursions, Micropulsations, Geonomy, The Earth’s Core and Geomagnetism, and was working on superchrons and changes in reversal frequency at Reversals of the Earth’s Magnetic Field, and the four volumes of the end. Contents List of Contributors xv Bemmelen, Willem van (1868–1941) 44 Art R.T. Jonkers Preface xxv Benton, E. R. 44 David Loper Aeromagnetic Surveying 1 Mark Pilkington Bingham Statistics 45 Jeffrey J. Love Agricola, Georgius (1494–1555) 3 Allan Chapman Biomagnetism 48 Michael D. Fuller and Jon Dobson Alfvén Waves 3 Christopher Finlay Blackett, Patrick Maynard Stuart, Baron of Chelsea (1887–1974) 53 Alfvén, Hannes Olof Gösta (1908–1995) 6 Michael D. Fuller Carl-Gunne Fälthammar and David Gubbins Bullard, Edward Crisp (1907–1980) 54 Alfvén's Theorem and the Frozen Flux Approximation 7 David Gubbins Paul H. Roberts Carnegie Institution of Washington, Department of Terrestrial Anelastic and Boussinesq Approximations 11 Magnetism 56 Stanislav I. Braginsky and Paul H. Roberts Gregory A. Good Anisotropy, Electrical 20 Carnegie, Research Vessel 58 Karsten Bahr Gregory A. Good Antidynamo and Bounding Theorems 21 Champ 59 Friedrich Busse and Michael Proctor Stefan Maus Archeology, Magnetic Methods 23 Chapman, Sydney (1888–1970) 61 Armin Schmidt Stuart R.C. Malin Archeomagnetism 31 Coast Effect of Induced Currents 61 Donald D. Tarling Ted Lilley Auroral Oval 33 Compass 66 Stephen Milan Art R.T. Jonkers Baked Contact Test 35 Conductivity Geothermometer 69 Kenneth L. Buchan Ted Lilley Bangui Anomaly 39 Conductivity, Ocean Floor Measurements 71 Patrick T. Taylor Steven Constable Barlow, Peter (1776–1862) 40 Convection, Chemical 73 Emmanuel Dormy David Loper Bartels, Julius (1899–1964) 42 Convection, Nonmagnetic Rotating 74 Karl-Heinz Glaßmeier and Manfred Siebert Andrew Soward Bauer, Louis Agricola (1865–1932) 42 Core Composition 77 Gregory A. Good William F. McDonough viii CONTENTS Core Convection 80 D00 as a Boundary Layer 145 Keke Zhang David Loper Core Density 82 D00, Anisotropy 146 Guy Masters Michael Kendall Core Motions 84 D00, Composition 149 Kathryn A. Whaler Quentin Williams Core Origin 89 D00, Seismic Properties 151 Francis Nimmo Thorne Lay Core Properties, Physical 91 Della Porta, Giambattista (1535–1615) 156 Frank D. Stacey Allan Chapman Core Properties, Theoretical Determination 94 Demagnetization 156 David Price Jaime Urrutia-Fucugauchi Core Temperature 98 Depth to Curie Temperature 157 David Price Mita Rajaram Core Turbulence 101 Dipole Moment Variation 159 Bruce Buffett and Hiroaki Matsui Catherine Constable Core Viscosity 104 Dynamo Waves 161 Lidunka Vočadlo Graeme R. Sarson Core, Adiabatic Gradient 106 Dynamo, Backus 163 Orson L. Anderson Ashley P. Willis Core, Boundary Layers 111 Dynamo, Braginsky 164 Emmanuel Dormy, Paul H. Roberts, and Andrew Soward Graeme R. Sarson Core, Electrical Conductivity 116 Dynamo, Bullard-Gellman 166 Frank D. Stacey Graeme R. Sarson Core, Magnetic Instabilities 117 Dynamo, Disk 167 David R. Fearn Jack A. Jacobs Core, Thermal Conduction 120 Dynamo, Gailitis 169 Frank D. Stacey Agris Gailitis Core-Based Inversions for the Main Geomagnetic Field 122 Dynamo, Herzenberg 170 David Gubbins Paul H. Roberts Core-Mantle Boundary Topography, Implications for Dynamics 124 Dynamo, Lowes-Wilkinson 173 Andrew Soward Frank Lowes Core-Mantle Boundary Topography, Seismology 125 Dynamo, Model-Z 174 Andrea Morelli Rainer Hollerbach Core-Mantle Boundary, Heat Flow Across 127 Dynamo, Ponomarenko 175 Stéphane Labrosse Paul H. Roberts Core-Mantle Coupling, Electromagnetic 130 Dynamo, Solar 178 Richard Holme Eugene N. Parker Core-Mantle Coupling, Thermal 132 Dynamos, Experimental 183 Jeremy Bloxham Andreas Tilgner Core-Mantle Coupling, Topographic 135 Dynamos, Fast 186 Dominique Jault Michael Proctor Cowling, Thomas George (1906–1990) 137 Dynamos, Kinematic 188 Leon Mestel Philip W. Livermore Cowling's Theorem 138 Dynamos, Mean-Field 192 Friedrich Busse Karl-Heinz Raedler Cox, Allan V. (1926–1987) 139 Dynamos, Periodic 200 Kenneth P. Kodama David Gubbins Crustal Magnetic Field 140 Dynamos, Planetary and Satellite 203 Dhananjay Ravat David J. Stevenson D00 and F-Layers 145 Earth Structure, Major Divisions 208 David Gubbins Brian Kennett CONTENTS ix Elsasser, Walter M. (1904–1991) 214 Geodynamo, Symmetry Properties 306 Eugene N. Parker David Gubbins EM Modeling, Forward 215 Geomagnetic Deep Sounding 307 Dmitry B. Avdeev Roger Banks EM Modeling, Inverse 219 Geomagnetic Dipole Field 310 Gary