Radiocarbon After Four Decades RADIOCARBON R.E

Radiocarbon After Four Decades RADIOCARBON R.E. Taylor A. Long R.S. Kra Editors

Radiocarbon After Four Decades An Interdisciplinary Perspective

With 148 Illustrations

Springer Science+Business Media, LLC R.E. Thylor Austin Long Department of Anthropology Department of Geosciences Institute of Geophysics and Planetary Physics The University of Arizona University of California, Riverside Thscon, AZ 85721 USA Riverside, CA 92521-0418 USA Renee S. Kra Department of Geosciences The University of Arizona Thscon, AZ 85721 USA

Library of Congress Cataloging-in-Publication Data Radiocarbon after four decades: an interdisciplinary perspective / [editors], R.E. Taylor, Austin Long, Renee S. Kra. p. cm. Includes bibliographical references and index. ISBN 978-1-4757-4251-0 ISBN 978-1-4757-4249-7 (eBook) DOI 1O.l007/978-1-4757-4249-7 1. Radiocarbon dating. I. Taylor, R. E. (Royal Ervin), 1938- II. Long, Austin. III. Kra, Renee S. QC798.D3R3 1992 546'.6815884-dc20 91-44448

Printed on acid-free paper. © 1992 Springer Science+BusinessMedia New York Originally published by Springer-Verlag New York, Inc. in 1992 Softcover reprint of the hardcover 1st edition 1992 All rights reserved. This work may not be translated or copied in whole or in part without the written per• mission of the publisher,Springer Science+Bnsiness Media, LLC, except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereaf• ter developed is forbidden. The use of general descriptive names, trade names, trademarks, etc., in this publication, even if the former are not especially identified, is not to be taken as a sign that such names, as understood by the Trade Marks and Merchandise Marks Act, may accordingly be used freely by anyone. Production managed by Ellen Seham; manufacturing supervised by Robert Paella. Camera-ready copy provided by the editors.

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ISBN 978-1-4757-4251-0 FOREWORD

Four decades have passed since the beginning of the use of radiocarbon as a dating, biological and environmental tracer isotope. More than thirty years ago, in December 1960, the Nobel Prize for Chemistry was bestowed on Willard Frank Libby (1909-1980) for the development of the radiocarbon C4C) method. One of the scientists who proposed Libby for the Nobel laureate characterized the significance of the 14C method in these words: "Seldom has a single discovery in chemistry had such an impact on the thinking of so many fields of human endeavor. Seldom has a single discovery generated such wide public interest" (Nobel Foundation 1964). On 4-8 June 1990, a conference at the University of California Lake Arrowhead Conference Center marked the major contributions that 14C has made to research in archaeology, biochemistry, environmental studies, geochemistry, geology, geophysics, hydrology and oceanography over the last forty years. Originally, plans for this conference had been discussed 15 years ago, following Libby's retirement in 1976 from the University of California, Los Angeles (UCLA). The proposed seminar was envisioned as a vehicle around which a Festschrift volume would have been developed. Libby's death in 1980, at the age of 71, terminated these plans. The concept of the Lake Arrowhead Conference arose from discussions among R E Taylor (University of California, Riverside), James Arnold (U ni versi ty of California, San Diego) and Ernest Anderson (retired from the University of California/Los Alamos National Laboratory). During 1948 to 1949 at the University of Chicago, James R Arnold - as a postdoctoral fellow - and Ernest C Anderson - as Libby's first graduate student at Chicago - carried out the critical experiments that established the essential validity of the 14C method. The involvement of R E Taylor resulted from the opportunity Willard Libby gave to a graduate student in archaeology/anthro• pology at UCLA to serve as a research assistant in Libby's Isotope Laboratory during the 1970s. In 1987, an International Advisory Committee was formed to provide counsel and direction in the organization of the conference. The members of this

v vi Foreword committee were Ernest C Anderson, James R Arnold, Paul E Damon, Gordon J Fergusson, Frederick Johnson, Kunihiko Kigoshi, Willem G Mook, Hans Oeschger, Ingrid U Olsson, Henry A Polach, Meyer Rubin, Hans E Suess, Minze Stuiver, Henrik Tauber and John C Vogel. A Local Organizing Commit• tee, consisting of Rainer Berger (UCLA), Jonathon E Ericson (University of California, Irvine) and R E Taylor, as Chair, was responsible for conference arrangements. The moderators for the six conference sessions were Paul E Damon (The University of Arizona) and Minze Stuiver (University of Washington) for the Natural Carbon Cycle; Henry A Polach (Australian National University) for Instrumentation and Sample Preparation; Willem G Mook (University of Groningen) for Hydrology; Fred Wendorf (Southern Methodist University) for Old World Archaeology and Paleoanthropology; Rainer Berger and R E Taylor for New World Archaeology; Meyer Rubin (United States Geological Survey) for Earth Sciences; and Lloyd A Currie (National Institute of Standards and Technology) for Environmental Sciences. Historical and New Approaches Theme Lectures, held in the evenings, inspired the participants with anecdotal reminiscences and great expectations for future trends. The moderators all did excellent jobs of organizing their sessions, inviting scientists who are experts in their respective fields. "New faces" blended with the "old guard" of the international radiocarbon community, as feelings of pride, admiration and accomplishment permeated the beautiful summer setting of Lake Arrowhead. This volume, a culmination of the discussions and presentations at Lake Arrowhead, is a unique tribute to the achievements of radiocarbon dating over the last forty years. Few 20th century scientific discoveries have had such a profound interdisciplinary impact. The chapters represent overviews of the history, development and future trends in the field, documenting the far-reaching influence that radiocarbon has had on a wide spectrum of scientific disciplines - including archaeology, astrophysics, biology, chemistry, dendrochronology, environmental sciences, geosciences, hydrology, oceanography, palynology and physics. For the first time, specialists have gathered to assess comprehensively the broad nature and consequences of the introduction of radiocarbon into the carbon cycle.

R E Taylor, Austin Long and Renee S Kra

REFERENCE

Nobel Foundation 1964 Nobel Lectures, Chemistry 1942-1962. Amsterdam, Elsevier: 587-588. Acknowledgments The conference organizers are indebted, for generous financial support of the conference, to the Center for Accelerator Mass Spectrometry (CAMS), University of California/Lawrence Livermore National Laboratory (UC/LLNL), as well as to the Willard F Libby Foundation, the Systemwide University of California Administration, Systemwide Institute of Geophysics and Planetary Physics (lGPP), UCLA Branch of the IGPP, University of California, Riverside (UCR) campus administration, University of California, Irvine (UCI) campus administration, UCLA campus administration, the UCLA Department of Chemistry and the Society for Archaeological Sciences. We particularly wish to thank Jay C Davis (CAMS) and Orson L Anderson (Systemwide IGPP) for their support and encouragement, and acknowledge the helpful suggestions of Minze Stuiver and other members of the International Advisory Committee for the design of the conference logo. We wish to express our sincere appreciation to Donna Kirner for her efficient management of the Lake Arrowhead Conference, as well as the very helpful assistance of Jeffrey Lehman, Louis Pay en, Joye Sage and Anna Weaver. The editors most gratefully acknowledge Harry E Gove and Donald 0 Henry, who did not attend the conference, but nonetheless, contributed significant chap• ters to this volume. Assistant Editor of RADIOCARBON, Frances D Moskovitz, played a key role in the physical production of this book, and we sincerely thank her for it. For their invaluable help in shaping the final content of this volume, we wholeheartedly acknowledge the work of the reviewers of the original manuscripts: Brian Atwater Mebus A Geyh Jim Phillips Bryant Bannister Herbert Haas L Neil Plummer Mike F Barbetti P Edgar Hare Henry A Polach Edouard Bard Calvin J Heusser George C Reid Edward Boyle Frank Hole Don S Rice Wallace S Broecker Gordon Jacobi Fred N Robertson Michael D Coe Jack R Jokipii Meyer Rubin Tyler B Coplen A J T Jull Garth Sampson Lloyd A Currie Mark J Kenoyer Jim G Shaffer Paul E Damon George A Klouda Michael B Schiffer George A Dawson J L Lanzerotti Kerry Sieh Owen K Davis John H Law Charles P Sonett James M Devine David C Lowe Thomas W Stafford, Jr Robert Earl Dickinson Richard H Meadow Jerry J Stipp Douglas J Donahue Clement W Meighan Michael Thurman David Elmore Willem G Mook Pierre M Vermeersch George W Farwell Andrew Moore John S Vogel Gordon J Fergusson John E Noakes Martin Wahlen Joan Feynman Tsung-Hung Peng Al Yang George Frison Fred M Phillips ungli~ Svenska Vetellskaps• ak3demien har vid sin Sa1l11nan• komst den J novenlber 1960 i enlig-• hermed.foreskrffterna i det" all ALFRED NOBEL den 27 nOl'enlber1895 upprattatU te5i~mentet beslutat art ol-'erlamna. tkt pris som dena ar borrgil'(s.f6r den l'ikti{!"asre kemiska upptJck~ eller.f6rltittrin~ nIt WILLARD F. LIBBY _f6r hans upprickr- al' kol-14 som tidmaidre inom arkeoZog£ ~eolo~ geC!fysik m,,}l, v(ttn5kaper/ Stockholm den 10 december 1960/

Libby's Nobel Award Photo courtesy of Leona Marshall Libby and the Libby Foundation; © The Nobel Foundation 1960 Willard Frank Libby (1905-1980) Nobel Laureate in Chemistry for 1960 for the development of the radiocarbon method of dating (Photo by Edward F Greer, December 1970; Courtesy of the Libby Foundation) Participants of the conference, "Four Decades of Radiocarbon Studies: An Interdisciplinary Perspective," 4-8 June 1990, Lake Arrowhead, California CONTENTS

Foreword v Acknowledgments vii Contributors xv Editors xviii

HISTORICAL PERSPECTIVES

Preface by R E Taylor 1 1. The Early Years With Libby at Chicago: A Retrospective James R Arnold with Robert L Schuch 3 2. The Early Radiocarbon Years: Personal Reflections Hans E Suess 11

THE NATURAL CARBON CYCLE Preface by Paul E Damon 17 3. Calibration of the Radiocarbon Time Scale, 2500-5000 Be Minze Stuiver and Gordon W Pearson 19 4. The History of Dendrochronology and Radiocarbon Calibration Bernd Becker 34 5. The Present Status of Understanding of the Long-Period Spectrum of Radiocarbon Charles P Sonett 50 6. Glacial-to-Interglacial Changes in Ocean Circulation Jean-Claude Duplessy, Maurice Arnold, Edouard Bard Laurent Labeyrie, Josette Duprat and Jean Moyes 62 7. Reconstruction of Radiocarbon Distribution in the Glacial Ocean Tsung-Hung Peng and Wallace S Broecker 75

xi xii Contents

8. Radiocarbon Fluctuations and the Geomagnetic Field Robert S Sternberg 93 9. Solar Forcing of Global Climate Change? Paul E Damon and John L Jirikowic 117 10. Radiocarbon and Astrophysical-Geophysical Phenomena G E Kocharov 130 11. Cosmogenic In Situ Radiocarbon on the Earth Devendra Lal 146

INSTRUMENTATION AND SAMPLE PREPARATION Preface by Austin Long 163 12. Sample Treatment Strategies in Radiocarbon Dating REM Hedges 165

13. CO2 Gas Proportional Counting in Radiocarbon Dating - Review and Perspective Bernd Kromer and Karl Otto Munnich 184 14. Four Decades of Progress in 14C Dating by Liquid Scintillation Counting and Spectrometry Henry A Polach 198 15. The History of AMS, Its Advantages Over Decay Counting: Applications and Prospects HE Gove 214 16. Radiocarbon Accelerator Mass Spectrometry: Background, Precision and Accuracy Roell P Beukens 230

HYDROLOGY Preface by Willem G Mook 241 17. Chemical and Isotopic Constraints on 14C Dating of Groundwater Jean-Charles Fontes 242 18. Effects of Parameter Uncertainty in Modeling 14C in Groundwater F J Pearson, J r 262 Contents xiii

19. Numerical Modeling With Groundwater Ages Mebus A Geyh 276 20. Natural Radiocarbon in Dissolved Organic Carbon in Groundwater Austin Long, Ellyn M Murphy, Stanley N Davis and Robert M Kalin 288

OLD WORLD ARCHAEOLOGY Preface by Fred Wendorf 309 21. The Impact of Radiocarbon Dating on North African Archaeology Fred Wendorf 310 22. The Impact of Radiocarbon Dating on Near Eastern Prehistory Donald 0 Henry 324 23. Radiocarbon Dating and the Prehistory of Sub-Saharan Africa Peter Robertshaw 335

NEW WORLD ARCHAEOLOGY

Preface by R E Taylor 353 24. Contributions of Radiocarbon Dating to the Geochronology of the Peopling of the New World C Vance Haynes, Jr 355 25. Radiocarbon Dating of Bone: To Collagen and Beyond R E Taylor 375 26. The Role of Radiocarbon Dating in Maya Archaeology: Four Decades of Research Scott L Fedick and Karl A Taube 403 27. Libby's UCLA Radiocarbon Laboratory: Contributions to Archaeology Rainer Berger 421

EARTH SCIENCES Preface by Meyer Rubin 435 28. Determining Recurrence Intervals of Great Subduction Zone Earthquakes in Southern Alaska by Radiocarbon Dating George Plafker, K R LaJoie and Meyer Rubin 436 xiv Contents

29. Major Contributions of Radiocarbon Dating to Palynology: Past and Future Dorothy M Peteet 454 30. Origin of Global Meltwater Pulses Richard G Fairbanks, Christopher D Charles and James D Wright 473

ENVIRONMENTAL SCIENCES Preface by Lloyd A Currie 501 31. Radiocarbon in Atmospheric Carbon Dioxide and Methane: Global Distribution and Trends Ingeborg Levin, Rainer Basinger, Georges Bonani Roger J Francey, Bernd Kromer, K 0 Milnnich Martin Suter, Neil B A Trivett and Willy Walfli 503 32. Environmental Impact of Atmospheric Carbon-14 Emissions Resulting from the Nuclear Energy Cycle R L Otlet, M J Fulker and A J Walker 519 33. Mankind's Perturbations of Particulate Carbon Lloyd A Currie 535

BIOMEDICAL APPUCATIONS Preface by Austin Long 569 34. Radiocarbon in the Biological Sciences Martyn Jope and Margaret Jope 570 35. New Biomedical Applications of Radiocarbon J C Davis 580

Index 591 CONTRIBUTORS

James R Arnold, Department of Chemistry, B-017, University of California, San Diego, La Jolla, California 92093 USA Maurice Arnold, Laboratoire Mixte CNRS-CEA, Centre des Faibles Radioactivites, Parc du CNRS, F-91198 Gif sur Yvette CCdex, France Edouard Bard, Laboratoire Mixte CNRS-CEA, Centre des Faibles Radioactivites, Parc du CNRS, F-91198 Gif sur Yvette Cedex, France Bernd Becker, Institut fiir Botanik, Universitat Hohenheim, Garbenstrasse 30, Postfach 700562, D-7oo0 Stuttgart 70 Germany Rainer Berger, Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California 90024 USA Roelf P Beukens, IsoTrace Laboratory, University of Toronto, 60 St George Street, Toronto, Ontario M5S lA7 Canada Georges Bonani, Institut fiir Mittelenergiephysik, ETH-Honggerberg, CH-8093 Ziirich, Switzerland Rainer BOllinger, Institut fiir Umweltphysick, Universitat Heidelberg, 1m Neuenheimer Feld 366, D-6900 Heidelberg, Germany Wallace S Broecker, Lamont-Doherty Geological Observatory, Columbia University, Palisades, New York 10964 USA Christopher D Charles, Lamont-Doherty Geological Observatory and Department of Geological Sciences, Columbia University, Palisades, New York 10964 USA Lloyd A Currie, Center for Analytical Chemistry, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 USA Paul E Damon, Department of Geosciences, The University of Arizona, Tucson, Arizona 85721 USA Jay C Davis, Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, PO Box 808, Livermore, California 94550 USA Stanley N Davis, Department of Hydrology and Water Resources, The University of Arizona, Tucson, Arizona 85721 USA Jean-Claude Duplessy, Laboratoire Mixte CNRS-CEA, Centre des Faibles Radioactivites, Parc du CNRS, F-91198 Gif sur Yvette Cedex, France Josette Duprat, Laboratoire de Geologie et Oceanographie, Universite de Bordeaux-I, Avenue des Facultes, 33405 Talence, France Richard G Fairbanks, Lamont-Doherty Geological Observatory and Department of Geological Sciences, Columbia University, Palisades, New York 10964 USA

xv xvi Contributors

Scott L Fedick, Department of Anthropology, University of California, Riverside, California 92521-0418 USA Jean-Charles Fontes, Laboratoire d'Hydrologie et de Geochimie Isotopique, Universite Paris-Sud, F-91405 Orsay CCdex, France Roger J Francey, CSIRO, Division for Atmospheric Research, PO Box 77, Aspendale, Victoria, Australia M J Fulker, British Nuclear Fuels, Ltd, Sellafield, Seascale, Cumbria CA20 1PG England Mebus A Geyh, Niedersachsisches Landesamt fur Bodenforschung, 14C und Tritium Labora• torium, Stilleweg 2, Postfach 51 01 53, D-3000 Hannover 53 Germany Harry E Gove, Nuclear Structure Research Laboratory, University of Rochester, Rochester, New York 14627 USA C Vance Haynes, Jr, Departments of Anthropology and Geosciences, The University of Arizona, Tucson, Arizona 85721 USA Robert E M Hedges, Radiocarbon Accelerator Unit, Research Laboratory for Archaeology and the History of Art, Oxford University, 6 Keble Road, Oxford OX1 3QJ England Donald 0 Henry, Department of Anthropology, The University of Tulsa, 600 South College Ave, Tulsa, Oklahoma 74104-3189 USA John L Jirikowic, Department of Geosciences, The University of Arizona, Tucson, Arizona 85721 USA Martyn Jope and Margaret Jope, 1 Chalfont Road, Oxford, England Robert M Kalin, Department of Geosciences, The University of Arizona, Tucson, Arizona 85721 USA G E Kocharov, AF loffe Physical-Technical Institute, Academy of Sciences, Polytechnicheskaya 26, St Petersburg 194021 Russia Bernd Kromer, Institut fUr Umweltphysik, Universitat Heidelberg, 1m Neuenheimer Feld 366, D-6900 Heidelberg, Germany Laurent Labeyrie, Laboratoire Mixte CNRS-CEA, Centre des Faibles Radioactivites, Parc du CNRS, F-91198 Gif sur Yvette Cedex, France K R Lajoie, Branch of Engineering, Seismology and Geology, U S Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 USA Devendra Lal, Geological Research Division A-020, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093-0220 USA Ingeborg Levin, Institut fUr Umweltphysick, Universitat Heidelberg, 1m Neuenheimer Feld 366, D-6900 Heidelberg, Germany Austin Long, Department of Geosciences, The University of Arizona, Tucson, Arizona 85721 USA WiIIem G Mook, Netherlands Institute for Sea Research (NIOZ), PO Box 59, 1790 Ab Den Burg Texel, The Netherlands Jean Moyes, Laboratoire de Geologie et Oceanographie, Universite de Bordeaux-I, Avenue des Facultes, 33405 Talence, France Karl Otto Miinnich, Institut fUr Umweltphysik, Universitlit Heidelberg, 1m Neuenheimer Feld 366, D-6900 Heidelberg, Germany Contributors xvii

Ellyn M Murphy, Battelle Pacific Northwest Laboratories, PO Box 999, Richland, Washington 99352 USA Robert L Otlet, RadioCarbon Dating, Downs Croft, The Holloway, Harwell, Oxfordshire OXll OLS England Fred J Pearson, Ground-Water Geochemistry, 1304 Walnut Hill Lane, Suite 210, Irving, Texas 75038 USA Gordon W Pearson, Palaeoecology Centre, The Queen's University of Belfast, Belfast BT7 INN Northern Ireland Tsung-Hung Peng, Environmental Science Division, Oak Ridge National Laboratory, Bldg 1000, MS-6335, Oak Ridge, Tennessee 37831-6335 USA Dorothy M Peteet, Goddard Institute for Space Studies, National Aeronautics and Space Administration, 2880 Broadway, New York, New York 10025 USA George Plafker, Branch of Alaskan Geology, MS-904, US Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 USA Henry A Polach, Research Consultations, Inc, PO Box 43, Garran, ACT 2605 Australia Peter Robertshaw, Department of Anthropology, California State University, San Bernardino, California 02407 USA Meyer Rubin, Radiocarbon Laboratory, US Geological Survey, National Center 971, Reston, Virginia 22092 USA Robert L Schuch, Sandia National Laboratories, Albuquerque, New Mexico 87185 USA Charles P Sonett, Department of Planetary Sciences and Lunar and Planetary Laboratory, The University of Arizona, Tucson, Arizona 85721 USA Robert S Sternberg, Department of Geology, Franklin and Marshall College, PO Box 3003, Lancaster, Pennsylvania 17604-3003 USA Mioze Stuiver, Quaternary Isotope Laboratory AJ-20, Department of Geological Sciences, University of Washington, Seattle, Washington 98195 USA Hans E Suess, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92037 USA Martin Suter, Paul Scherrer Institut, c/o ETH-Honggerberg, CH-8093 ZUrich, Switzerland Karl A Taube, Department of Anthropology, University of California, Riverside, California 92521-0418 USA R E Taylor, Radiocarbon Laboratory, Department of Anthropology and Institute of Geophysics and Planetary Physics, University of California, Riverside, California 92521-0418 USA N B A Trlvett, Atmospheric Environment Service, 4905 Dufferin Street, Downsview, Ontario M3H ST4 Canada A J Walker, RadioCarbon Dating, Downs Croft, The Holloway, Harwell, Oxfordshire OX11 OLS England Fred Wendorf, Department of Anthropology, Southern Methodist University, Dallas, Texas 75275 USA Willy WOIfli, Institut fUr Mittelenergiephysik, ETH-Honggerberg, CH-8093 Zurich, Switzerland James D Wright, Lamont-Doherty Geological Observatory and Department of Geological Sciences, Columbia University, Palisades, New York 10964 USA EDITORS

R E Taylor is an archaeologist/archaeometrist in the Department of Anthropology and Institute of Geophysics and Planetary Physics, University of California, Riverside. His principal interest involves the application of 14C and other Quaternary dating methods to provide temporal place• ment for archaeological materials. Over the last decade, his research has focused on the 14C dating of bone as specifically applied to the dating of New World human skeletal materials in the context of controversies concerning the character and timing of the peopling of the western hemisphere. He was involved in early applications of AMS technology in 14C measurements of human bone. He is the author of Radiocarbon Dating: An Archaeological Perspective (Academic Press 1987) and co-editor (with C W Meighan) of Chronologies in New World Archaeology (Academic Press 1978). His current appointment at UCR is Professor of Anthropology and Director, Radiocarbon Laboratory. He came to UCR in 1969 following the completion of graduate studies at UCLA, where he served as a Research Assistant in the Isotope Laboratory of the late Willard F Libby.

Austin Long became interested in geochemistry in 1956, as an undergraduate summer intern at Lamont Geological Observatory. While working on his PhD under Paul Damon at The University of Arizona, he helped convert the Libby-style solid carbon dating laboratory to a 14C gas proportional laboratory. In 1963, Long joined the staff of the Smithsonian Institution, and with Joel Sigalove, turned out their first methane gas-proportional dates. In 1968, Long returned to Arizona to become director of the Radiocarbon Laboratory, and added a stable isotope facility as well. Long has supervised a number of MS and PhD students, primarily in isotope geohydrology. In 1987, coincident to moving it to a new underground counting chamber, the laboratory was converted to exclusively liquid scintillation counting. Long became Editor of RADIOCARBON late in 1988, and in January 1989, the editorial offices moved to Tucson as part of the Geosciences Department. As Editor, he has been active in involving eastern Europe in the radiocarbon community, and he is stressing quality assurance in 14C dating.

Renee S Kra has been Managing Editor of RADIOCARBON for 25 years. She started her long-term affair with RADIOCARBON in the Geology and Geophysics Department at Yale University, under the aegis of Edward S Deevey, Richard Foster Flint and Irving Rouse, the founders of the journal. With Minze Stuiver, who became Senior Editor in 1976, she co-edited the Proceedings of the 10th, 11th and 12th International Radiocarbon Conferences. With Austin Long, Editor since 1988, she has edited the 13th, and is currently working on the Proceedings of the 14th conference, held in Tucson in May 1991. In 1989, she moved with the journal to The University of Arizona, and became Assistant Research Scientist in the Geosciences Department. Kra has a Bachelor's degree in English and a Master's degree in Anthropology. She is Executive Director of the International Radiocarbon Data Base (IRDB), and is currently co-editing, with Ofer Bar• Yosef, a volume on Late Quaternary Chronology and Paleoclimates of the Eastern Mediter• ranean.

xviii