SOILS -OF THE- PAST TITLES OF RELATED INTEREST

Aeolian Introduction to theoretical W. G. Nickling (ed.) geomorphology Cathodoluminescence ofgeological C. Thorn materials Karst geomorphology and D. J. Marshall D. C. FordandP. W. Williams The changing climate Mathematics in M.J. Ford J. Ferguson Chemical fundamentals ofgeology Paleopalynology R. Gill A. Traverse Deep marine environments K. Pickering et a1. P. Duchaufour (translated by T. R. Paton) A dynamic stratigraphy of the British of the sedimentary rocks Isles J. T. Greensmith R. Anderton et al. A practical approach to sedimentology Environmental change and tropical R. C. Lindholm (ed.) geomorphology Principles ofphysical sedimentology I. Douglas and T. Spencer (eds) J. R. L. Allen Environmental chemistry Quaternary environments P. O'Neill J. T. Andrews (ed.) Environmental magnetism Quaternary paleoclimatology F. Oldfield and R. Thompson R. S. Bradley Experimentsin physical sedimentology Rocks and landforms J. R. L. Allen J. Gerrard Geomorphology and Sedimentary structures K. Richards et al. (eds) J. Collinson and D. Thompson Hillslope processes Sedimentology: process and product A. D. Abrahams (ed.) M.R. Leeder The history ofgeomorphology Trace fossils K. J. Tinkler (ed.) R. Bromley Image interpretation in geology Volcanic successions S. Drury R.A.F.CasandJ.V.Wright SOILS -OF THE- PAST An introduction to

G.J. RETALLACK University of Oregon, Eugene

Boston UNWIN HYMAN London Sydney Wellington © Gregory J. Retallack, 1990

This book is copyright under the Berne Convention. No reproduction without permission. All rights reserved.

Unwin Hyman, Inc., 8 Winchester Place, Winchester, Mass. 01890, USA

Published by the Academic Division of Unwin Hyman Ltd 15/17 Broadwick Street, London WIV IFP, UK

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First published in 1990 ISBN 978-0-04-445757-2 ISBN 978-94-01 1-7902-7 (eBook) DOl 10. I 007/978-94-0 I 1-7902-7

Library of Congress Cataloging-in-Publication Data

Retallack, Gregory J. (Gregory John), 1951- Soils of the past: an introduction to paleopedologylby Gregory J. Retallack. p.cm. Includes bibliographical references.

1. Paleopedology. I. Title. QE473.R4731990 552' .5--dc20 89-37143 CIP

British Library Cataloguing in Publication Data

Retallack Gregory J. Soils of the past. 1. Palaeosoils I. Title 551.7 ISBN 978-0-04-445757-2

Typeset in 10 on 12 point Palatino by Fotographics (Bedford) Ltd To Ken and Wendy Retallack, for letting me be Preface

Landscapes viewed from afar have a timeless quality that is soothing to the human spirit. Yet a tranquil wilderness scene is but a snapshot in the steady stream of surficial change. Wind, water and human activities reshape the landscape by means of gradual to catastrophic and usually irreversible events. Much of this change destroys past landscapes, but at some times and places, landscapes are buried in the rock record. This work is dedicated to the discovery of past landscapes and their life through the fossil record of soils. A long history of surficial changes extending back almost to the origin of our planet can be deciphered from the study of these buried soils, or . Some rudiments of this history, and our place in it, are outlined in a final section of this book. But first it is necessary to learn something of the language of soils, of what happens to them when buried in the rock record and which of the forces of nature can be confidently reconstructed from their remains. Much of this preliminary material is borrowed from science, but throughout emphasis is laid on features that provide most reliable evidence of landscapes during the distant geological past. This book has evolved primarily as a text for senior level university courses in paleopedology: the study of fossil soils. It is not the usual view of this subject from the perspectives of , Quaternary research or planning. It is rather the view of an Earth historian and paleontologist. Compared to the elegant outlines of a fossil skull or the intricate venation on a fossil leaf, fossil soils may at first appear unprepossessing subjects for scientific investigation. These massive, clayey and weathered zones are fossils in their own way. Their identifica• tion within a classification of modem soils presupposes particular past conditions, in the same way as the lifestyle that can be inferred from modem relatives of a fossil species of skull or leaf. Particular features of paleosols also may reflect factors in their formation in the same way as ancient diet can be inferred from the shape of fossil teeth or former climate from the marginal outline of a fossil leaf. This book is an exploration of the idea that paleosols are trace fossils of ecosystems. Examples in this book are drawn largely from my own work on fossil soils, some of it not yet published elsewhere. Theoretical concepts have been borrowed more widely from allied areas of science including geomorphology, coal petrography, plant ecology, astronomy and soil science, to name a few. The fossil record of soils is a new focus for integrating existing knowledge about land surfaces and their biota. Paleopedology remains an infant discipline, hungry for theory and data of the most elementary kinds. This book is one attempt to partially quell the growing pains.

Gregory J. Retallack, Eugene, Oregon, 1989

ix Acknowledgments

This book on paleosols would be slender indeed without extensive borrowing of facts, experiments, ideas and inspiration from allied areas of science. I have been fortunate to be able to draw upon the wise counsel of prominent sedimentologists O. R. L. Allen, A. Basu, D. R. Lowe, R. M. H. Smith and L. J. Suttner), paleontologists (R. Beerbower, A. K. Knoll, J. W. Schopf and P. Shipman), geochemists (G. G. Goles, J. M. Hayes, H. D. Holland and W. Holser) and soil scientists (P. W. Birkeland, S. W. Buol, L. D. McFadden and P. F. McDowell). Among the emerging cadre of paleopedologists concerned with rocks older than Quaternary, it is a pleasure to acknowledge stimulating discussions with D. E. Fastovsky, M. J. Kraus, W. R. Sigleoand V. P. Wright. Last, andcertainlynotleast, many of my ideas have been reshaped by students at the University of Oregon (E. A. Bestland, D. P. Dugas, C. R. Feakes, P. R. Miller, J. A. Pratt, S. C. Radosevich, G. S. Smith and G. D. Thackray). They gave real meaning to the Socratic dictum that the unexamined life is not worth living. Photographs, specimens and other illustrative materials were gener• ously and promptly provided by H. J. Anderson, J. B. Adams, H. P. Banks, T. M. Bown, J. Gray, R. Greeley, M. J. Kraus, S. C. Morris, NASA Space Science Center, C. J. Percival and V. P. Wright. Others graciously acquiesced in my adaptation of their published work. For several fine photographs (Figs. 3.5, 3.6, 21.1, and 21.3) I thank Sean Poston. Forreams of accurate word processing, I am indebted to C. D. Bonham and K. Fletcher. The writing would not have proceeded nearly so much to my satisfaction without the happy home life created by Diane, Nicholas and Jeremy.

We are grateful to the following individuals and organizations who have kindly given permission for the reproduction of copyright material (figure numbers in parentheses):

© 1952 University of Chicago Press (3.13); Table 4.1 part reproduced from Bodman & Mahmud, Soil Science 33, 363-74, © 1932 Williams and Wilkins; Figure 4.9 reproduced from Stephenson, Soil Science 107,470- 79, © 1969 Williams and Wilkins; Figure 9.1 reproduced with permission from L. R. Holdridge et ai., Forest Environments in Tropical Life Zones, © 1971 Pergamon Press PLC; Figure 9.2 reproduced with permission from Annual Review ofEarth and Planetary Sciences 7, © 1979 Annual Reviews Inc.; Figure 10.2 reproduced by permission from Perry & Adams, Nature 276, 489-91, © Macmillan Magazines Ltd; F10"111'<> 1 (l ~ ..0 ...... "...'1",..0...'1 t.~_

xi Soils of the Past

Wright, GeologicalJourna119, bypermissionofJohn Wiley&Sons© 1984; Figurel0.4reproducedfromJ. M. Andersonetal., Palaeoflora ofSou them Africa: Molteno Formation (Triassic) Vol. 1, 1983 by permission of A. A. Balkema; © 1969 University of Chicago Press (11.2, 11.3); Blackwell Scientific Publications (11.7, 16.2D); Figure 13.3 reproduced from Gile et al., Soil Science 101, 347-60, © 1966 Williams & Wilkins; Figure 15.5 reproduced with permission from Heiken et al., Proc. 4th Lunar Conference 1 and Proc. 7th Lunar Conference 1, © 1973 and 1976 Pergamon Press PLC; Figure 15.6 reproduced with permission from McKay et al., Proc. 5th Lunar Sdence Conference 1, © 1974 Pergamon Press PLC; Figures 16.1C, D, F, Hand 16.2C reproduced by permission from J. W. Schopf (ed.), Earth's Earliest Biosphere: its Origin and Evolution, © 1983 Princeton University Press; © American Association for Advance• ment of Science (16.1G); Figure 16.2A reproduced from Ronov, Geo• chemistry International 4, 713-37, by permission of John Wiley & Sons © 1964; © 1985 American Association for the Advancement of Science (16.2E).

xii Table of Contents

Preface ix Acknowledgments xi List of tables xvii

PART ONE: SOILS AND PALEOSOLS

1 Paleopedology 3

2 Soils on and under the landscape 9 Some technical terms for soils 10 Soils on the landscape 11 Quatemarypaleosols 13 Paleosols at major unconformities 14 Paleosols in sedimentary sequences 17

3 Features of fossil soils 20 Root traces 20 Soil horizons 30 38

4 Soil-forming processes 55 Indicators of physical weathering 55 Indicators of chemical weathering 62 Indicators ofbiological weathering 75 Generalized soil-forming regimes 86

5 91 Australian handbook 92 FAOworldmap 97 US soil taxonomy 99 A word of caution 112

6 Mapping and naming paleosols 114 Paleoenvironmental studies 115 Stratigraphic studies 122 Deeply weathered rocks 126

7 Alteration of paleosols after burial 129 Compaction 132

xiii Cementation 136 Neomorphism 137 Authigenesis 138 Replacement 138 Dissolution 139 Dehydration 140 Reduction 140 Base exchange 142 Carbonization 144

PART TWO: FACTORS IN SOIL FORMATION

8 Modelsofsoilformation 149

9 Climate 153 Some classifications of climate 154 Indicators of rainfall 161 Indicators of temperature 167 Indicators of seasonality 172

10 Organisms 176 Traces of organisms 178 Traces of ecosystems 206 Fossil preservation in paleosols 215

11 Topographicreliefasafactor 223 Indicators of past geomorphic setting 225 Indicators ofpast water table 230 Interpretingpaleocatenas 234

12 Parent material as a factor 240 General properties of parent materials 242 Some common parent materials 249 A base line for soil formation 255

13 Time as afactor 261 Indicators of development 264 Accumulation of paleosol sequences 276

PART THREE: FOSSIL RECORD OF SOILS

14 A long-term natural experiment in 291

xiv 15 Soils of otherworlds 295 Soils of the Moon 296 Soils of Venus 303 Soils of Mars 309 Meteorites 315 Relevance to early Earth 322

16 Earth's earliest landscapes 326 Oxygenation ofthe Earth's atmosphere 332 Differentiation of continental crust 341 Precambrian scenery 347

17 Early life on land 351 Did life originate in soil? 354 Evidence for early life in paleosols 366 Mother Earth or Heart of Darkness? 372

18 Large plants and animals on land 375 Evidence of multicellular organisms in paleosols 379 How did multicellular soil organisms arise? 388 Putting down roots 394

19 Afforestation of the land 399 Early forest soils 402 A diversifying landscape 409 A finer web oflife on land 413

20 Grasses in dry continental interiors 422 Early grassland soils 427 How did grasslands arise? 437 Evolutionary processes 441

21 Human impact on landscapes 446 Human origins 452 Early human ecology 458 A tamed landscape 463 On human nature 470

References 471 Index 507

xv List of tables

Table 3.1 Descriptive shorthand for labelling paleosol horizons. Table 3.2 Scale of acid reaction to approximate carbonate content of paleosols. Table 3.3 Sharpness and lateral continuity of boundaries of paleosol horizons. Table 3.4 Size abundance and contrast of mottles in paleosols. Table 4.1 Estimation of original density, moisture equivalents and porosity of paleosols. Table 4.2 Criteria for distinguishing between fossil charcoal and coalified wood fragments. Table 4.3 Common kinds of chemical reactions during weathering. Table 4.4 Estimation of major kinds of chemical reactions in paleosols using molecular weathering ratios. Table 4.5 Formulae relating volume, thickness and chemical changes in soil and fossil soil horizons during original soil forma• tion and subsequent burial and compaction. Table 4.6 Areas (X106 km2 ) and percentages of the Earth's surface occupied by major ecosystem types, their primary productivity (x 109 metric tons of carbon per year) and their productivity: area ratios. Table 9.1 Koppens classification of climates. Table 9.2 Climatic thresholds and climate-diagnostic values of peri• glacial features. Table 10.1 Kinds of microbes, their metabolic requirements and role in soils. Table 12.1 Estimating carbon dioxide and oxygen demand of parent materials from chemical data. Table 13.1 Stages of paleosol development. Table 13.2 Stages of carbonate accumulation in paleosols. Table 13.3 Stages of development of peaty soils. Table 13.4 Stages of mineral alteration in soils. Table 13.5 Temporal resolution (in years) and completeness (% of 1000-year time spans represented) in rock units in Badlands National Park, South Dakota. Table 15.1 Physical data on selected planetary bodies. Table 15.2 Chemical analyses of extraterrestrial soils and parent materials. Table 15.3 Abundance and characteristics of different kinds of meteorites. Table 17.1 Simplified metabolic processes of living organisms. Table 21.1 Traditional view of north-west European pedogenic trends during postglacial times, 13 000 years to present.

xvii