Contents

Preface

Acknowledgments

Introduction

Part I Regional scale geoarchaeology

Chapter 1 Sediments

1.1 Introduction

1.2 Types of sediments

1.3 Conclusions: sediments versus soils

Chapter 2 Stratigraphy

2.1 Introduction

2.2 Stratigraphy and stratigraphic principles

2.3 Facies and microfacies

2.4 Correlation

2.5 Keeping track: the Harris Matrix

2.6 Conclusions

Chapter 3 Soils

3.1 Introduction

3.2 Soil profiles and soil properties

3.3 The five soil forming factors

3.4 Important soil forming processes

3.5 Conclusions

Chapter 4 Hydrological systems I: slopes and slope deposits

4.1 Introduction

4.2 Water movement on slopes

4.3 Erosion, movement, and deposition on slopes

4.4 Conclusions

Chapter 5 Hydrological systems II: rivers and lakes

5.1 Introduction

5.2 Stream erosion, transport, and deposition

5.3 Stream deposits and channel patterns

5.4 Floodplains

5.5 Stream terraces

5.6 Lakes

5.7 Conclusions

Chapter 6 Aeolian settings and geoarchaeological environments

6.1 Introduction

6.2 Sandy aeolian terrains

6.3 Examples of sites in dune contexts

6.4 Bioturbation in sandy terrains

6.5 Fine grained aeolian deposits

6.6 Conclusions

Chapter 7 Coasts

7.1 Introduction

7.2 Palaeo sea shores and palaeo coastal deposits

7.3 Conclusions

Chapter 8 Caves and rockshelters

8.1 Introduction

8.2 Formation of caves and rockshelters

8.3 Cave deposits and processes

8.4 Environmental reconstruction

8.5 Conclusions

Part II Nontraditional geoarchaeological approaches

Chapter 9 Human impact on landscape: forest clearance, soil modifications, and cultivation

9.1 Introduction

9.2 Forest clearance and soil changes (amelioration, deterioration, and disturbance)

9.3 Forest and woodland clearance features

9.4 Cultivation and manuring

9.5 Landscape effects

9.6 Conclusions

Chapter 10 Occupation deposits I: concepts and aspects of cultural deposits

10.1 Introduction

10.2 Concepts and aspects of occupation deposits

10.3 Stratigraphic sequences as material culture; concepts and uses of space

10.4 Time and scale

10.5 Settlement–landscape interrelationships

10.6 Origin and predepositional history of occupation deposits

10.7 Depositional history

10.8 Postdepositional modifications

10.9 Conclusions

Chapter 11 Occupation deposits II: examples from the Near East, North America, and Europe

11.1 Introduction

11.2 Tells

11.3 Mounds

11.4 Urban archaeology of Western Europe

11.5 Early medieval settlement

11.6 Medieval floors of Northwest Europe

11.7 Conclusions

Chapter 12 Experimental geoarchaeology

12.1 Introduction

12.2 Effects of burial and aging

12.3 Experimental “Ancient Farms” at Butser and Umeå

12.4 Conclusions

Chapter 13 Human materials

13.1 Introduction

13.2 Constructional materials

13.3 Metal working

13.4 Conclusions

Chapter 14 Applications of geoarchaeology to forensic science

14.1 Introduction

14.2 Soils and clandestine graves

14.3 Provenancing and obtaining geoarchaeological information from crime scenes

14.4 Other potential methods

14.5 Practical approaches to forensic soil sampling and potential for soil micromorphology

14.6 Conclusions

Part III Field and laboratory methods, data, and reporting

Chapter 15 Field-based methods

15.1 Introduction

15.2 Regional-scale methods

15.3 Shallow geophysical methods (resistivity, palaeomagnetism, seismology, ground penetrating radar)

15.4 Coring and trenching techniques

15.5 Describing sections: soils and sediments in the field

15.6 Collecting samples

15.7 Sample and data correlation

15.8 Conclusions

Chapter 16 Laboratory techniques

16.1 Introduction

16.2 Physical and chemical techniques

16.3 Microscopic methods and mineralogy

16.4 Thin section analysis

16.5 Minerals and heavy minerals

16.6 Scanning Electron Microscope (SEM), EDAX, and microprobe

16.7 Conclusions

Chapter 17 Reporting and publishing

17.1 Introduction

17.2 Management of sites and reporting

17.3 Fieldwork and assessment/evaluation reporting

17.4 Postexcavation reporting and publication

17.5 Site interpretation

17.6 Conclusions

Chapter 18 Concluding remarks and the geoarchaeological future

Appendices

Bibliography

Index

Dedicated by RIM to the late Peter Reynolds (Butser Ancient Farm, United Kingdom) and Roger Engelmark (University of Umeå, Sweden): pioneers of experimental farms (see Chapter 12)

From RIM: to Mum, Jill, and Flora

From PG: to my folks for sending me away to summer camp

© 2006 by Blackwell Science Ltd, a Blackwell Publishing company

BLACKWELL PUBLISHING

350 Main Street, Malden, MA 02148-5020, USA

9600 Garsington Road, Oxford OX4 2DQ, UK

550 Swanston Street, Carlton, Victoria 3053, Australia

The right of Paul Goldberg and Richard I. Macphail to be identified as the Authors of this Work has been asserted in accordance with the UK Copyright, Designs, and Patents Act 1988.

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs, and Patents Act 1988, without the prior permission of the publisher.

First published 2006 by Blackwell Science Ltd

1 2006

Library of Congress Cataloging-in-Publication Data

Goldberg, Paul.

Practical and theoretical geoarchaeology/Paul Goldberg and Richard I. Macphail.

p. cm.

Includes bibliographical references and index.

ISBN 0-632-06044-1 (pbk. : alk. paper) 1. Archaeological geology. I. Macphail, Richard. II. Title.

CC77.5.G65 2006

930.1’028–dc22

                                                                                         2005018433

A catalogue record for this title is available from the British Library.

For further information on

Blackwell Publishing, visit our website:

www.blackwellpublishing.com

Preface

Geoarchaeology within the past two decades has become a fundamental discipline whose value is recognized by everyone interested in past human history. First, archaeologists have become increasingly sensitive to the fact that sediments and stratigraphy provide the ultimate context for the artifacts and features that they excavate. Understanding this sedimentary context and its implications is a requisite for carrying out modern archaeology and for interpreting the archaeological record fully and accurately. Environmentalists (e.g. paleoecologists, soil scientists, sedimentologists, geologists, biologists, and climatologists) on the other hand, have turned to archaeology, because it provides a long-term view of human–environment interactions that have shaped both Quaternary and Holocene landscapes. Such knowledge can have a critical bearing on the future, for example, through identifying areas of sustainable landuse. Interpretation of such ecological information depends upon detailed understanding of the pedosedimentary and geomorphological context, as in archaeology. Geoarchaeology is an important discipline, because as shown recently, it increases our understanding of human impacts on the landscape through the study of ancient soils and occupation deposits. These investigations can provide detailed histories of human endeavors up to the present.

Although geoarchaeology – though not defined as such – had its roots at least in the eighteenth century (Rapp and Hill, 1998) it never came together as a subdiscipline until the appearance of the edited volume “Geoarchaeology: Earth Science and the Past” by Davidson and Shackley (1976). At this time Renfrew (1976) coined the term “geoarchaeology” in his Preface. Since then, a number of texts have appeared, the earliest ones (e.g. Rapp and Gifford, 1985) again were collections of papers, which were followed by single authored volumes (e.g. Waters, 1992; Rapp and Hill, 1998). In most cases however, the archaeological and human element as geoarchaeology was often underexplored in favor of landscape studies. This present volume, Practical and Theoretical Geoarchaeology, attempts to address this deficiency by providing what we feel is a more balanced view of the discipline by including detailed investigations of human activities as revealed by geoarchaeology. Potentially fruitful avenues of expansion of the discipline are highlighted, for example, in chapters on caves, experiments, occupation deposits, and forensic applications.

This book aims to be both an educational and practical tool, describing how geoarchaeology is carried out across a wide range of environments and periods, employing examples from many countries. It endeavors to teach readers both how to approach geoarchaeological problems theoretically and how to deal with them in practice. The topics covered range from regional-scale studies down to smaller, open area excavations and strata in past and present urban areas, such as Roman and Medieval London. The book presents numerous field and laboratory techniques, exposing readers to approaches suitable to a variety of site situations. Instructive guidelines and protocols are given to show the reader how to create integrated reports that include field evaluations, laboratory assessments, and archive and publication reports.

The book is designed primarily for undergraduate students in Archaeology and those Environmental and Geoscientists, who wish either to train in geoarchaeology or gain a background in this applied science. It is intended to serve as a basic text and an intermediary course in geoarchaeology. It also serves as a necessary text for advanced undergraduates and postgraduate students requiring access to geoarchaeological skills. In addition, it should act as a valuable resource for professionals in order to help develop their awareness of both field and laboratory methods and to identify the full potential of geoarchaeological investigations either for research or mitigation archaeology. Beginners in the subject may benefit from reading Chapters 1 to 3 first, which provide introductions to stratigraphy, sediments, and soils.

Acknowledgements

Those who know us are keenly aware how long it has taken us to get this book together. We thank them here at the outset for their patience and any grief we might have inflicted. There are too many people to thank individually, but a number of folks helped us considerably in writing the book.

Early discussions with Wendy Matthews were very stimulating and helped frame the focus of the book. Similarly, before we were too far along, David Sanger provided some fundamental insights about geoarchaeology and its practitioners. He reminded us that most geoarchaeology books are not written by archaeologists. Again, we hope that this helped us steer a more equitable course on the subject. Along the way we benefited from extensive and intensive collaboration and picked up valuable insights from Ofer Bar-Yosef, Steve Weiner, Takis Karkanas, Trina Arpin, Sarah Sherwood, Carolina Mallol, Arlene Rosen, Harold Dibble, Shannon McPherron, Steve Kuhn, Mary Stiner, Susan Mentzer, Lauren Sullivan, as well as Mike Allen, John Crowther, Gill Cruise, Johan Linderholm, the late Peter Reynolds, and Pat Wiltshire.

The staff at Blackwell has been exemplary, especially in light of the experiences that the authors have had with publishers. Delia Sandford and Rosie Hayden provided congenial help with a great deal of enthusiasm: a sheer pleasure. They also supplied a good deal of forgiveness and support along with Ian Francis, our editor. It was his questionable idea to contact us in the first place, and we are grateful for the opportunity to capitalize on it.

Students at Hebrew University, Boston University, the University of Tours, and the Institute of Archaeology, and members of the Archaeological Soil Micromorphology Working Group served as test subjects for various parts of this book over the years. Colleagues at HU (Na’ama Goren-Inbar, Nigel Goring-Morris, Anna Belfer-Cohen, and Erella Hovers) offered immense opportunities to observe exciting real-time geoarchaeology. Nigel Goring-Morris, simply one of the best field archaeologists around, furnished several examples of key sites that really helped build a geoarchaeological story. Colleagues at Texas (Mike Collins, Tom Hester, Britt Bousman, Lee Nordt, Charles Frederick) provided a different outlook and a growing experience, in spite of the accent. The years of field work at Dust Cave with Boyce Driskell revealed that anthropogenic deposits exist even for hunters and gatherers in the New World.

Over the years, the interaction with many geoarchaeologists similarly shaped our thinking. At the outset, the late Henri Laville served as an inspiration for cave sediments, along with Prof. F. Bordes. Marie-Agnès Courty has carried on this tradition of scholarship and friendship and has set the bar for geoarchaeological standards. Our first collaboration with her was invigorating and subsequent geoarchaeological interactions have helped us all develop and profit. We continue to be indebted to her.

Reid Ferring and PG were graduate students working in the Negev in the early 1970s and the latter has gained lots of insights into New World and Old World, geology, archaeology, and geoarchaeology, particularly in the field, waiting for things to happen. Rolfe Mandel and Vance Holliday, are among the foremost geoarchaeology practitioners, and they were instrumental in providing support, knowledge, and insights over the years. Much of this was sharpened by sharing the editorial helm with Rolfe at Geoarchaeology. Many hours were spent talking about the state of the discipline and the people who practice it. Vance Holliday in particular, devoted a lot of his time to furnish us with timely, constructive comments that significantly improved our message and how we should get it across. Not only are all these folks helpful, but they are simply nice people and made collaboration a pleasure. We also specifically would like to thank our other reviewer (from the United Kingdom), and Gill Cruise who played the devil’s advocate with parts of the text. Duncan FitzGerald provided valuable advice on several chapters.

Over the years, we have been encouraged by many other people and organizations who also supplied us with help, support, and information: Bud Albee, Nick Barton, Nick Bateman, Martin Bell, Francesco Berna, Sandra Bond, Mike Bridges, Barbara Brown, Brian Byrd, Dana Challinor, Nick Conard, Jane Corcoran, Andy Currant, John Darlymple, Roger Engelmark, John G. Evans, Nick Fedoroff, Charly French, Henri Galinié, Anne Gebhardt, Daffyd Griffiths, Ole Grøn, Simon Groom, Joachim Henning, John Hoffecker, Bruce Larson, Tom Levy, Elisabeth Lorans, Stephen Macphail, Curtis Marean, Roberto Maggi, Dominic Powlesland, Kevin Reeves, Mark Roberts, Thilo Rehren, Philippe Rentzell, Pete Rowsome, Tim Sara, Solveig Schiegl, Joe Schuldenrein, Astrid Schweizer, Christine Shaw, Jane Sidell, Michela Spataro, Julie Stein, Chris Stringer, Kathryn Stubbs, Ken Thomas, Peter Ucko, Brigitte Vliet-Lanöe, Steve Weiner, Alasdair Whittle, Tim Williams, Liz Wilson, Jamie Woodward, Elizabeth Zadora-Rio, the Universities of Frankfurt and Tours, the Institute of Archaeology (UCL), The Alexander von Humboldt Foundation, University of Tübingen, Albion Archaeology, Butser Ancient Farm, Corporation of London, English Heritage, Framework Archaeology, Museum of Londan Archaeology Service Norfolk Archaeological Unit, Suffolk Archaeological Unit, Oxford Archaeology, and Wessex Archaeology. We are grateful to all of you.

Introduction

Geoarchaeology has become highly prominent these days, and geoarchaeological themes appear in journal articles, monographs, and reports, either within a specific section of an article or as a stand-alone publication. Journals embrace not only mainstream “geoarchaeological” type of publications, such as Geoarchaeology or the Journal of Archaeological Science, but also other journals that touch on more mainstream archaeological, anthropological, or geological subjects: Journal of Human Evolution, American Antiquity, Journal of Sedimentary Research, and Antiquity. In the United States, annual meetings of both the Geological Society of America (GSA) and the Society for American Archaeology (SAA), generally have at least one session or poster session, in addition to society-sponsored symposia on the subject. The GSA has an Archaeological Geology Division, and the SAA has the Geoarchaeology Interest Group. The Association of American Geographers (AAG) commonly has geoarchaeology sessions at their annual meetings.

Moreover, the most exciting archaeological sites that one reads about today – either in the popular press or professional literature – commonly have a substantial geoarchaeological component. The reader has only to be reminded about the significance of the geoarchaeological aspect of sites that are concerned with major issues relating to human development and culture. Some high profile issues and sites include: the use and evidence of the controlled use of fire (Zhoukoudian, China); the sedimentary context and the origin of early hominins (Dmanisi, Republic of Georgia; Boxgrove, United Kingdom; Mediterranean and South African caves – Gorham’s Cave, Gibraltar; Kebara Cave, Israel; Blombos Cave, South Africa); peopling of the New World (Meadowcroft Rockshelter United States; Monte Verde, Chile); Near Eastern urban cultures (Çatal Höyük, Turkey; Abu Salabikh and Tel Leilan, Syria), and early management of domestic animals (Arene Candide, Italy). Even previously excavated localities, such as the Folsom site, are being reinvestigated from a more sophisticated geoarchaeological perspective.

These well-known landmark sites have really drawn attention to the contribution that geoarchaeology can make to, and its necessity in, modern archaeological studies. This situation was not the case a few decades ago when only a handful of archaeological projects utilized the skills of the geoarchaeologist; one of the authors (PG) could enumerate the sparse number of geoarchaeological studies at the time he was a graduate student in the late 1960s. Still, the best results have come from highly focused geoarchaeological investigations that have employed the appropriate techniques, and that have been intimately linked to multidisciplinary studies that provide consensus interpretations.

This book is about how to approach geoarchaeology and use it effectively in the study of archaeological sites and contexts. We shall not enter into any detailed discussion of the origins and etymology of “Geoarchaeology” versus “Archaeological Geology.” (Full discussions of this irrelevant debate can be found in Butzer, 1982; Courty et al., 1989; Rapp, 1975; Rapp and Hill, 1998; Waters, 1992.) In a prescient, no-frills view of the subject Renfrew (1976: 2) summed it up concisely and provided these insights into the nature of geoarchaeology:

This discipline employs the skills of the geological scientist, using his concern for soils, sediments and land-forms to focus these upon the archaeological “site,” and to investigate the circumstances which governed its location, its formation as a deposit and its subsequent preservation and life history. This new discipline of geoarchaeology is primarily concerned with the context in which archaeological remains are found. And since archaeology, or at least prehistoric archaeology, recovers almost all its basic data by excavation, every archaeological problem starts as a problem in geoarchaeology.

These issues of context, and what today would be called “Site Formation Processes” in its broadest sense, can and should be integrated regionally to assess concerns of site locations and distributions, and geomorphic filters that might have controlled them.

In this book – as will be seen throughout the volume – we take a decidedly pragmatic and functional approach. We do not see any need to differentiate between the two and consider geoarchaeology, archaeological geology, and geological archaeology to fall under the same rubric: any issue or subject that straddles the interface between archaeology and the earth sciences. Classifications – and in this case the distinctions between geoarchaeology and archaeological geology – are of value only if they are ultimately useful. Does it really matter how we categorize research that is aimed at studying postdepositional dissolution of bones at a site? According to the above this research would fall into both camps, but does it help us to know if we are doing geoarchaeology or geological archaeology or archaeological geology? For the sake of brevity, we employ the simple term, Geoarchaeology.

Geoarchaeology is practiced at different scales (Stein and Linse, 1993). Furthermore, its use and practice vary according to the training of the people involved and the goal of their study. For example, geologists and geographers may well emphasize the mapping of large-scale geological and geomorphological features – such as where a site may be situated within a drainage system – or other regional landscape features. This is a regional perspective scale that exists in three dimensions, with relative relief possibly being measured in thousands of meters, especially if working in the Alps and Andes. Much of the geoarchaeological research carried out in North America is focused at this landscape scale. Geologists would also be interested in the overall stratigraphy of site deposits and how these might interrelate to major landforms, such as stream terraces, glacial landforms, and loess plateaus. Pedologists, on the other hand, would be more concentrated on the parent materials, the surfaces upon which soils were formed, and how both have evolved in conjunction with the landscape; such materials can be buried by subsequent deposition or can be found on the present-day surface. In either case, pedologists’ focus tends to be on the scale of the soil pit, that is, on the order of meters. Archaeologists themselves may want to focus geoarchaeological attention upon microscale, centimeter-thick occupation deposits: what they are, and how they reflect specific or generalized past human activities. In the case of rescue/mitigation archaeology – commonly termed Cultural Resource Management (CRM) in the United States – geoarchaeology is tailored to the nature of the “job specifications” proscribed by the developer under the guidelines of salvage operations. Finally, the geoarchaeologist may well be just one member of an environmental team whose task is to reconstruct the full biotic/geomorphic/pedologic character of a site and its setting, and how these environments interacted with past human occupations. All these approaches can be relevant depending on the research questions involved, and holistically they could be subsumed under the term, “site formation processes” (Schiffer, 1987).

Archaeologists come from a variety of backgrounds. As stated above, in North America, archaeology is taught predominantly in anthropology programs, although some universities (e.g. Boston University, United States, and Simon Fraser University in Canada) actually have archaeology departments; Classical and Near Eastern Archaeology programs are not rare, and these tend to emphasize written sources over excavation. In Europe, archaeology is included within programs, or in departments and institutes, and not necessarily as an extension of anthropology.

Although in the United Kingdom, geoarchaeology is taught in a number of archaeological departments, this is not always the case in Europe as a whole. In France, for example, this subject may only be taught to prehistorians and not to classical or medieval archaeologists. Commonly, even in the United Kingdom and elsewhere in the world, geoarchaeology is more likely to be seen as an ad hoc offshoot of geology and geography. In North America, it is not anchored in any particular department and may be cross-listed among Anthropology, Archaeology, Geology, and Geography. In spite of good intentions and good training, many geoscientists tend to be naïve in their approach to solving archaeological problems, and as a consequence they effectively reduce their potential in advancing this application of their science. This often diminishes or even negates their contributions to interdisciplinary projects. The opposite situation can be found, where an archaeologist does not even know what questions to ask (Goldberg, 1988; Thorson, 1990).

Thus, as Renfrew (1976) so cogently demonstrated, geoarchaeology provides the ultimate context for all aspects of archaeology from understanding the position of a site in a landscape setting to a comprehension of the context of individual finds and features. Without such knowledge, even the most sophisticated isotope study has limited meaning and interpretability. As banal as it might sound, the adage, “garbage-in, garbage-out” is wholly pertinent if the geoarchaeological aspects of a site are ignored.

In the past, geoarchaeology was carried out very much by individual innovators. In North America, the names Claude Albritton Jr., Kirk Bryan, E. Antevs, E.H. Sellards, and C. Vance Haynes immediately come to mind as the early and prominent leaders in incorporating the geosciences into the framework of archaeology (see Holliday, 1997 and Mandel, 2000a for details). In fact, Mandel aptly points out that for the Great Plains, geoarchaeology – or at least geological collaboration – locally constituted an active part of archaeological survey for several areas, although it was patchy in space and time. Much of the emphasis was focused on evaluating the context of Paleoindian sites and how these occurrences figured into the peopling of the New World (Mandel, 2000).

In Europe, during the period from the 1930s to the 1950s, Zeuner (1946, 1953, 1959) at the Institute of Archaeology (now part of University College London), developed worldwide expertise in the study of the geological settings of numerous Quaternary and Holocene sites that ranged from India to Gibraltar. After Kubiëna (1938, 1953, 1970) called the world’s attention to soil micromorphology, Cornwall (1958) also at the Institute of Archaeology, applied this technique to archaeology for the first time (see below). At the same time, Dimbleby (1962) developed the link between archaeology and environmental studies, and produced one of the first detailed investigations of past vegetation and monument-buried soils for Bronze Age England Dimbleby (1962). Duchaufour (1982) in France also systematically studied environmental change and pedogenesis. In mainland Europe, the legendary French prehistorian François Bordes (1954) – whose doctorate in geology dealt with the study of loess, paleosols, and archaeological sites, principally in Northern France – placed the French Palaeolithic within its geomorphologic setting. Vita-Finzi (1969), working in the Mediterranean Basin, used archaeological sites to suggest the chronology of Mediterranean valley fills, which he related to both climatic and anthropogenic factors. Cremaschi (1987) investigated paleosols and prehistoric archaeology in Italy.

Although some geoarchaeological research is funded by granting agencies (NSF, NGS, NERC, CNRS), much, if not most, of modern geoarchaeological work – in both the New and Old Worlds – is fostered and sponsored by CRM projects, ultimately related to human development throughout the world. Approaches and job specifications vary according to whether investigations are at one end of the spectrum, short-term one-off studies, or long-term research projects at the other. Geoarchaeological work can be done by single private contractors or by huge international teams, which may well include specialists who also act as private contractors. Nowadays, local authorities, government agencies (e.g. State Departments of Transportation in the United States) and national research funding agencies (e.g. NSF in the United States, AHRB and English Heritage in the United Kingdom, AFAN and the CNRS in France, and Nara National Institute in Japan) may all be involved in commissioning geoarchaeological investigations. It is currently a very flexible field. It is also one where there is an increasing need for formal training, but where relatively few practitioners have been in receipt of one.

Geoarchaeological work is now often broken up into several phases, with desktop investigations, fieldwork survey, excavation, sample assessment, and laboratory study, all being likely precursors to full analysis and final publication. This is all part of modern funding and operational procedures.

Single-job or site-specific studies may be as straightforward as finding out “What is this fill?” whereas problem-based research could involve the gathering of geoarchaeological data on the possible first controlled use of fire, as at Zhoukoudian, China (Goldberg et al., 2001; Weiner, 1998). Sites are investigated at different scales and sometimes, for very different reasons. At one time “dark earth” – the dark colored Roman-medieval urban deposits found in urban sites across northern Europe – engaged the particular interest of geoarchaeologists because these enigmatic deposits commonly span the “Dark Ages,” and human activities at this time were poorly understood (Macphail, 1994; Macphail et al., 2003). Analysis of “dark earth” therefore, became a research-funded topic for urban development sites (CRM projects in urban areas) across Belgium, France, and the United Kingdom, for example. On the other hand, attention can be focused on individual middens and midden formation because they provide a wealth of material remains, particularly organic, that are normally poorly preserved and complex to understand and interpret (Stein, 1992). Regional studies of the intertidal zone, for example, may include the investigation of middens as one single component. The recent study of the intertidal deposits of the River Severn around Goldcliff, Wales, for example, involved analysis of sediment and drowned soils in order to investigate sea level changes and their effects on the populations living in the coastal zone during the Mesolithic through Iron Age periods (Bell et al., 2000). Equally, studies of alluvial deposits and associated flood-plains (Brown, 1997; French, 2003) have involved the search for buried sites, within the overall realm of evaluating the distribution of archaeological sites. The Po plain of Italy (Cremaschi, 1987) and the Yellow River of China (Jing et al., 1995) both feature a series of late prehistoric settlements. Many of the most significant Paleoindian and Archaic sites in the United States are situated within alluvial sequences (Ferring, 1992, 1995; Mandel, 1995, 2000a).

Modern geoarchaeological research makes use of a vast number of techniques that either have been used in geology and pedology or have been developed or refined for geoarchaeological purposes. Early geoarchaeological research until the latter part of the last century, at least in North America, was predominantly field-based and made use of both natural exposures and excavated areas. More recently, field techniques have become more improved and technologically sophisticated (Hester et al., 1997). Natural exposures can be supplemented with surface satellite remote sensing data (Scollar, 1990), as well as subsurface data derived from machine-cut backhoe trenches, augering, coring, and advanced geophysical techniques (e.g. magnetometry, electrical resistivity, and ground penetrating radar-Kvamme, 2001). Moreover, such data can be assembled and interrogated using Geographic Information Systems (GIS; Wheatley and Gillings, 2002) that can be used to generate and test hypotheses.

Laboratory techniques have similarly become more varied and sophisticated. At the outset, many geoarchaeological studies adopted techniques from geology and pedology that were aimed at sediment/soil characterization. Thus traditional techniques characteristically consisted of grain-size analysis (granulometry), coupled with other physical attributes (e.g. particle shape, bulk density, bulk mineralogy), as well as basic chemical analyses of organic matter, calcium carbonate content, extractable iron, and so on. The analysis of phosphate to elucidate activity areas or demarcate site limits has a longer history spanning over 70 years (Arrhenius, 1931, 1934; Parnell et al., 2001). Conventional techniques with long historical pedigrees, such as x-ray diffraction (XRD), electron microprobe, x-ray fluorescence (XRF), instrumental neutron activation analysis (INAA), and atomic absorption (AA) have been enhanced by rapid chemical, elemental, and mineralogical analyses of samples through the use of Fourier transform infrared spectrometry (FTIR), Raman spectrometry, and inductively coupled plasma atomic emission spectrometry (ICP-AES) (Pollard and Heron, 1996).

In addition, a notable advance in geoarchaeology has been the application of soil micromorphology to illuminate a wide variety of geoarchaeological issues (Courty et al., 1989; French, 2003). These issues range from the development of soil and landscape use (e.g. Ayala and French, 2005; French and Whitelaw, 1999; Romans and Robertson, 1983) and the formation of anthropogenic deposits (Macphail et al., 1994; Matthews, 1995; Matthews et al., 1997) to the evaluation of the first uses of fire (Goldberg et al., 2001).

Finally, geoarchaeological research has been facilitated by the development of numerous dating techniques just within the past two to three decades. Now, sites within the span beyond the widely accessible limits of radiocarbon are potentially datable with techniques, such as thermoluminescence (TL), optically stimulated luminescence (OSL), and electron spin resonance (ESR) (Rink, 2001).

In this book, we aim to present a fundamental, broad-based perspective of the essentials of modern geoarchaeology in order to demonstrate the breadth of the approaches and the depth of problems that can be tackled. As such, it is also aimed to promote a basic line of communication and understanding among all multidisciplinarians. We cover a variety of topics that discuss thematic issues, as well as practical skills. The former encompasses such broad concepts as stratigraphy, Quaternary and environmental studies, sediments, and soils. We then provide a survey of some of the most common geological terrains that provide the natural settings for almost all archaeological sites. These are established geoarchaeological topics into which we have incorporated some new findings. Unlike previous books on geoarchaeology, we have dedicated a second major portion of the volume to new topics that are normally not entertained by previous geoarchaeological texts, such as “human impact,” “experiments,” and occupation deposits including Roman and medieval archaeology, and forensic applications. It is important also to obtain some insights into practical aspects of geoarchaeology, including how specifically geoarchaeologists should fit in to a project. Similarly, two chapters are devoted to a presentation of the methods – pragmatic and theoretical – currently used in geoarchaeology. These include not only field techniques (e.g. the use of aerial photos, how to describe a profile, and collect samples), but also those techniques that are used in the laboratory. Although we summarize the “what,” and “how,” we also try to emphasize the “why,” and provide a number of example-based caveats for important techniques. A final facet deals with the practical aspects of reporting geoarchaeological results, keeping in mind that material presented in reports differs from that in articles. Reports essentially present the full database and arguments, whereas articles are commonly more thematic and focused, and by necessity are constrained to present results more concisely. Reports, which are seldom published in full, constitute the “gray literature” and make up an important part of the scientific database. They are too commonly overlooked, ignored, or simply are not readily accessible.

As a final point, we maintain that geoarchaeology in its broadest sense, must be made understandable to all players involved, be they archaeologists with strong training in anthropology, or the geophysicist, with minimal exposure to archaeological issues. All participants should have enough of a background to understand what each participant is doing, why they are doing it, and most importantly, what the implications of the geoarchaeological results are for all team members. Too often we hear about the geospecialist simply turning over results to the archaeologist, essentially being unaware of the archaeological problem(s), both during the planning stages and later during execution of the project. Hence they cannot correctly put their results to use. On the other hand, many archaeologists tacitly accept results produced by specialists with few notions on how to evaluate them. This book attempts to level the playing field by providing a cross-disciplinary background to both ends of the spectrum. Such basic material is needed to establish a dialogue among the participants so that problems can be mutually defined and mutually understood, regardless of whether you call yourself an archaeological geologist or geoarchaeologist.

Part I

Regional scale geoarchaeology

Introduction to Part I

Geoarchaeological endeavors operate at a variety of scales. These undertakings range from regional views of archaeological sites – their distributions and associated activities (e.g. cultivation, hunting ranges, trading routes, and networks) – to microscopic study of the deposits, artifacts, and features found within them. In the following chapters we examine the issues linked to landscape scale geoarchaeology, and describe the most salient aspects of some of the principal geological environments and processes that geoarchaeologists are likely to encounter. Although archaeological sites and associated remains can be found in most geological environments (including what is now marine; Faught and Donoghue, 1997), most human occupations, or at least their traces, are not evenly spread throughout these environments. Sites associated with temperate fluvial (stream) environments, for example, are considerably more abundant than those from desertic or glacial terrains. Thus, although we try to touch on all these situations, we may provide more detail for those with greater representation in the geoarchaeological record. Detailed treatises on geological environments can be found in many geomorphology and sedimentology texts, such as Boggs, 2001; Easterbrook, 1993; Reading, 1996; and Ritter et al., 2002.

1

Sediments

1.1 Introduction

Sediments – those materials deposited at the earth’s surface under low temperatures and pressures (Pettijohn, 1975) – constitute the backbone of geoarchaeology. The overwhelming majority of archaeological sites is found in sedimentary contexts, and the material that is excavated – whether geogenic or anthropogenic – is sedimentary in character. In this section we examine some of the basic characteristics of sediments, many of which can also be applied to soils (Chapter 3). We have two principal goals in mind. Since sediments are so ubiquitous in archaeological sites, it is necessary to have at least a working knowledge of some of these characteristics so as to be able to share this descriptive information with others. Essentially, these descriptive characteristics constitute a lingua franca: the term “sand” (Table 1.1), for example, corresponds to a defined range of sizes of grains, irrespective of composition. Second, and perhaps more important, is that many of the descriptive parameters that we observe in sediments commonly reflect – either individually or collectively – the history of the deposit, including its (1) origin, (2) transport, and (3) the nature of the locale where it was deposited, that is, its environment of deposition. Figuring out these three aspects of a sediment’s history constitutes a subliminal mindset of sedimentologists, whether they are studying a 100 m thick sequence of Carboniferous sandstones in Pennsylvania or a 10 cm thick sandy layer within a Late Pleistocene cave in the Mediterranean. In sum, by observing and recording the lithological attributes of a sediment we not only provide an objective set of criteria to describe it, but also a means to get some insights into its history.

1.2 Types of sediments

Sediments can be classified into three basic types, clastic, chemical, and organic, of which the first two are generally the most pertinent to geoarchaeology. Clastic sediments are the most abundant type. They are composed of fragments of rock, other sediment, or soil material that reflect a history of erosion, transport, and deposition. Most clastic sediments are terrigenous and deposited by agents such as wind (e.g. sand dunes), running water (e.g. streams, beaches), and gravity (e.g. landslides, slumps, colluvium). Typical examples of clastic sediment (as based on decreasing sizes of the components) are sand, silt, and clay (Table 1.1). In the geological record, when such materials become lithified, the resulting rock types are sandstone, siltstone, and shale, respectively.

Volcaniclastic debris, consisting of volcanic ash, blocks, bombs, and pyroclastic flow debris are also considered as clastic sediments (Fisher and Schmincke, 1984), Overall, they are relatively uncommon in geoarchaeological contexts as they are restricted to volcanic areas. Nevertheless, they constitute an important aspect in the stratigraphy and formation of some key archaeological sites. Pompeii, considered the type site for depicting instances in archaeological time (Binford, 1981), is covered by about 4 m of volcaniclastic debris (tephra), consisting of pumice, volcanic sand, lapilli (2–64 mm), and ash (<2 mm) (Giuntoli, 1994). The site of Ceren, in San Salvador, represents a similar type of setting, where structures and agricultural fields were buried under several meters of tephra (Conyers, 1995; Sheets, 1992). Volcaniclastic deposits in rift valleys play critical roles in the dating and stratigraphy of Pliocene and Pleistocene deposits from sites in East Africa, the Jordan Rift, Turkey, and Georgia. Sites such as Olduvai Gorge, Koobi Fora, Gesher Benot Ya’akov, and Dmanisi, are just a few of the sites where archaeological and hominin remains are intercalated with volcanic rocks and tephra (Ashley and Driese, 2000; Deocampo et al., 2002; Gabunia et al., 2000; Goren-Inbar et al., 2000; Stern et al., 2002).

TABLE 1.1 Common grain size scales used in geology and pedology

Marine organisms such as mollusks and corals, for example, produce shells of calcium carbonate. In cases where these hard body parts are subjected to wave action, they can be broken into small centimeter to millimeter size fragments, resulting in the formation of a bioclastic limestone, for example (Table 1.2). Coquina is an example of a coarse bioclastic sediment, whereas chalk is composed of silt and fine sand-size tests of marine organisms (foraminifera); in other cases organisms may have siliceous skeletons as is the case with diatoms, resulting in the formation of diatomite. Biological remains, such as ostracods, diatoms, and foraminifera, can be preserved within otherwise mostly mineralogenic deposits. The moat deposits from the Tower of London, for example, contained numerous diatoms that suggested shallow, turbid water in disturbed sediments (Keevill, 2004). These conditions were inferred to be a result of inputs into the moat of waste disposal, surface water, and water from the Thames and the City Ditch.

TABLE 1.2 Types of sediments; consolidated (lithified), rock equivalents for clastic sediments are given in parenthesis. Note that bioclastic limestones, composed of biologically precipitated shell fragments (e.g. coquina), can be thought to be both clastic and biochemical in origin

Chemical sediments are those produced by direct precipitation from solution. Lakes in semiarid areas with strong evaporation, for example, will exhibit a number of precipitated minerals, such as halite (table salt), gypsum (calcium sulphate), or calcite or aragonite (both forms of calcium carbonate). In cave environments, chemical sediments are widespread and typically produce sheets of calcium carbonate (e.g. travertine or flowstone), or ornaments such as stalactites and stalagmites. These are usually composed of calcite or aragonite, but other peculiar minerals can be composed of phosphates, nitrates, or sulphates (Hill and Forti, 1997). The third group, biological sediments, is composed mostly of organic materials, typically plant matter. Peats or organic-rich clays in swampy areas and depressions are characteristic examples.

1.2.1 Descriptive and interpretative characteristics of sediments

1.2.1.1 Clastic sediments

Clastic sediments display a number of properties that can be described and ultimately interpreted. These characteristics include composition, texture (grain size and shape), fabric, and sedimentary structures.

Composition. Sediments can exhibit a wide variety of composition of mineral and rock types, and normally this is a function of the source of the material (Tables 1.3 and 1.4). For this reason, geologists are able to reconstruct geological landscapes (e.g. former landmasses in Table 1.4) that have long since been eroded. In spite of their wide variety, certain rocks and minerals occur repeatedly in sediments (“major minerals” in Table 1.3). Their relative abundance in a sediment can vary with location and age. In the case of the latter, some minerals (e.g. olivine) are more susceptible to alteration/destruction than others, and thus they can be less persistent in older sediments. Furthermore, overall sediment composition can be influenced by secondary processes (e.g. weathering, soil formation, diagenesis) that result in the precipitation of minerals that either cement the skeletal grains of the sediment, or that precipitate as concentrations within the sedimentary mass (e.g. nodules and concretions). Secondary mineralization may involve carbonates (e.g. calcite, aragonite), silicates (e.g. opal, microcrystalline quartz/chert), sulfates (e.g. gypsum, barite), and iron oxides (e.g. limonite, goethite).

Texture involves attributes of individual grains themselves, and these like other traits, have both descriptive and interpretative value. One of the most basic and widespread attributes is that of grain size (Table 1.1), and it is one that both geoscientists and archaeologists use and intuitively understand: “this deposit is fine grained, while the one in the corner is quite gritty to sandy.” Obviously we have to be more precise than this example, and both geologists and pedologists employ formal names and size limits to describe the classes of particle sizes that range from fine, micron-size (1 µm = 0.001 mm) grains of dust, up to large boulders several meters across.

TABLE 1.3 Common minerals and rock fragments in sediments (modified from Boggs, 2001)

TABLE 1.4 Heavy mineral associations and related geological sources (modified from Pettijohn et al., 1973)

The grain size scale commonly used by geologists in the United States is that developed by Wentworth (1922) (Table 1.1); note that this scale is a geometric grade scale with the limits between classes having a constant ratio of 1/2 (Krumbein and Sloss, 1963). Geologists have later modified this by introducing the phi (Φ) scale, which is a logarithmic transformation of the grain size to the base 2 (Φ = −log₂d, where d is the grain size in millimeter). These arithmetic intervals are convenient for the graphical presentation of grain size data, such as histograms (see Chapter 16), and for performing statistical analyses. In any case, as can be seen in Table 1.1, the limit between silt and clay is 3.9 µm in the Wentworth scale, and the limit between silt and sand is 62.5 µm. Furthermore, it is important to note that soil scientists (in both the United States and United Kingdom) employ different limits between sand/silt and silt/clay: for soils in the United States, silt includes material between 50 and 2 µm, whereas in the United Kingdom, it is 63–2 µm (Table 1.1). These differences are particularly significant while evaluating data in reports and maps, and whether the descriptions have been done by a geologist or pedologist: the same sediment can have different percentages of silt or sand, depending upon who it was analyzed by a geologist or a pedologist.

FIGURE 1.1