©2011 Emmanuel Kimuma Ndiema ALL RIGHTS RESERVED

Home , Ard (plough), Hyrax Hill, Ileret, Koobi Fora, Lake Turkana, The Barrier (Kenya)

2011

Emmanuel Kimuma Ndiema

KOOBI FORA, NORTHERN KENYA: NEW ARCHAEOLOGICAL SITES AND EVIDENCE FROM

OBSIDIAN SOURCING AND GEOCHEMICAL CHARACTERIZATION

EMMANUEL KIMUMA NDIEMA

A Dissertation submitted to the

Graduate School-New Brunswick

Rutgers, The State University of New Jersey

in partial fulfillment of the requirements

for the degree of

Doctor of Philosophy

Graduate Program in Anthropology

written under the direction of

J. W. K. Harris

and approved by

______

New Brunswick, New Jersey

October, 2011 ABSTRACT OF THE DISSERTATION

MOBILITY AND SUBSISTENCE PATTERNS AMONG MID HOLOCENE PASTORALISTS AT

KOOBI FORA, NORTHERN KENYA: NEW ARCHAEOLOGICAL SITES AND EVIDENCE FROM

OBSIDIAN SOURCING AND GEOCHEMICAL CHARACTERIZATION

By EMMANUEL KIMUMA NDIEMA

Dissertation Director:

J. W. K. Harris

The emergence of managed food production laid the foundation for the emergence of complex economies and social structures in the world today. Land use territorial organization and long distance interaction patterns were important aspects for prehistoric lifeways. The chemical composition of stone artifacts can be used to identify places that ancient people visited and document changes in mobility patterns and scales of their interaction. This study was conducted at Koobi Fora, a UNESCO world heritage site on Lake Turkana in Northern Kenya and addresses the questions of inception of livestock and the mobility patterns of early herders in the region.

Survey for obsidian sources and excavations at five Pastoral Neolithic sites were conducted to develop a high-resolution database for obsidian artifacts in the Galana Boi

Fm., Koobi Fora. The artifacts and geological reference samples from five sites were

analyzed using Energy dispersive X-ray Fluorescence and Inductively Coupled Plasma

Mass Spectrometry. Artifact distance fall-off curves as well as faunal and ceramic

attributes of sample from over 50m2 of excavation were used to document mobility

patterns and scales of interaction among early herder population in the Turkana Basin,

Sites were dated using Optically Stimulated Luminescence yielding dates from ~4.4 ka

BP to ~1,0 ka BP. This period occurs during falling lake level and increasing aridity.

The results show different sources of obsidian were used irrespective of

distance. There were also other undocumented sources were either coming from within

or outside the Turkana Basin. Similarities in ceramic decorations indicate that culture

contact was more important than migration to social economic change in Turkana Basin.

It would seem that high mobility patterns were extensive but did not destroy hunter

gatherer habitat but allowed local hunter-gatherer subsistence and social organization

to co-exist. Contact between groups would have maximized use of different micro

habitant. It would appear that inception of herding in Turkana Basin therefore was

variable, complex and should be understood in the context of local ecological conditions

during periods of intense climate variability.

iii

ACKNOWLEDGEMENTS

I am deeply humbled to know that this dissertation is a culmination of many years of support from countless persons and institutions. These pages also reflect the relationships with many generous and inspiring people I have met throughout my graduate work. The list is long, and I cannot mention each and every one individually but

I cherish each and everyone’s contribution to my career development.

First I would like to acknowledge my advisor Prof. J. W. K. Harris, for his excellent

guidance, patience, and providing me with an excellent atmosphere. He not only gave

me all his support in the field and practical issues beyond the textbooks, but patiently

assisted me get financial support for my research. I am also indebted to my committee

members Dr. Susan Cachel, Prof Gail Ashley, Drs. Carolyn Dillian, David Braun and Purity

Kiura and Lee Cronk. You all went beyond the call of duty and supported my work in

various ways that I cannot name them all. Special thanks go to Drs. Cachel and Cronk,

who were willing to participate in my final dissertation committee at short notice. Dr.

Dillian, I thank you for guiding me through my first published paper. It is from your seed that I have been able to publish another one. Dr. Braun you have walked with me

through many paths that I cannot mention here. Thank you for guiding me right from a

naïve field worker to a full‐fledged researcher that I aspire to be. Dr. Kiura, how you

manage to be a mentor, boss, friend, and a big sister to look up to are beyond my

comprehension‐ I just want to say Asante! Prof. Ashley, I thank you for driving all the

way to the lab to assist me in my dissertation even during spring break. I cannot forget

how you obtained funds to date the samples and tirelessly spent time helping me with

the geological sections and making sure I understood what they meant. Dr Cronk, words

cannot thank you enough for all your support advice as GPD and stepping in at the last

minute to sit in my dissertation committee-Sere nyo woo

Funding for training at Rutgers University was provided by the Wenner-Grenn

Foundation through the Wadsworth International Fellowship. Funding for the various

phases of this research and related components was generously provided by the following organizations: Paleontological Scientific Trust, (PAST) The Wenner-Grenn

Foundation, Centre fro Human Evolutionary Studies student Grant (CHES), Bigel

Fellowship, Preliminary Dissertation Research grant (Rutgers Graduate School-New

Brunswick) and the British Institute in Eastern Africa (Minor research grant). For all of which I am humbly grateful.

I thank the many institutions that facilitated the analysis of my samples, the

Geology Dept. at the University of Cape Town (UCT), Archaeology XRF lab at UC –

Berkeley, and Dr. Spencer at Kansas University. Of course I cannot forget the National

Museums of Kenya for providing the space permission and all the support to undertake my research. I thank all the field research crew John Mwangi, Wole, Paul Watene, Tom

Mukhuyu, Ben Sila and all the “super stars” of Northern Kenya.

I stand on the shoulders of many giants, and I would like to thank those who taught, guided me, gave advice, and shared ideas. I also thank all the graduate students in the lab and the Anthropology graduate program, Lori Dibble, Steve, Jay, Sarah

Melanie, Jane, Pante, Chaunetta, Drew, and Dillon among many other wonderful people

v I was fortunate enough to work with. Luca Morino deserves special mention for being my roommate for all those years. Luca, thank you for putting-up with me despite my short comings. To the McCoy family, I thank all of you for proving me with a family away from home. In your home I have found comfort, friendship and joy. I pray that this friendship continues to posterity.

Finally I thank my family for all the support, most of all, my mother Grace

Chepkesis who could not be here to see this work to completion. John Wilson deserves special mention for helping me get an education. My Wife Lillian for putting up with my prolonged absence and taking care of our home. Dan and Olivia this is all for you!!!

And to all of you that I did not mention I just want to say Thank you! Asante

Sana!

vi Dedication

In memory of my mother

Grace Chepkesis Ndiema

In God you rest, but in our hearts you live forever

vii TABLE OF CONTENTS

ABSTRACT ...... ii Acknowledgements ...... iv Dedication ...... vii TABLE OF CONTENTS...... vii LIST OF TABLES ...... xi LIST OF FIGURES ...... xii CHAPTER ONE: Scientific Frameworks Leading to a Better Understanding for the Earliest Stage of Pastoralism from Lake Turkana ...... 1 1.1 Introduction ...... 1 1.2 Hunter-gatherer economic strategies and social organization … ...... 3 1.3 Applying models of hunter-gatherer societies to the past ...... 7 1.4 Forager-food producer interactions in the past and present ...... ….10 1.5 Aspects of obsidian sourcing faunal and ceramics and problems of convergence or equifinality ...... 16 1.6 Research goal and hypotheses ...... 21 1.7 Summary; Goals of research and organization for thesis ...... 24 1.8 Cultural historic framework ...... 25 1.9 Early/ Later Stone Age occupations ...... 25 1.10 Early pottery cultures ...... 26 1.11 The Pastoral Neolithic and the spread of pastoralism ...... 28 1.12 Savanna Pastoral Neolithic (SPN) ...... 30 CHAPTER TWO: Geological, Environmental and Archaeological Background ...... 36 2.1 Introduction ...... 36 2.2 Location ...... 37 2.3 Geological sedimentary setting and stratigraphy ...... 43 2.4 History of Holocene research in Turkana Basin ...... 47 2.5 Paleoenvironmental reconstruction and climate change ...... 51 2.6 Obsidian quality and availability in Turkana Basin ...... 57 CHAPTER THREE: Site Descriptions ...... 62 3.1 Introduction ...... 62 3.2 Procedures and methods of excavation ...... 62 3.3 Excavations ...... 66 3.4 GaJi 4 (Dongodien) ...... 69 3.4.1 Dating ...... 70 3.4.2 Local geology and stratigraphy ...... 72 3.4.3 Archaeological assemblage ...... 73 3.4.4 Paleoenvironmental Context ...... 74 3.5 Area 10 deposits ...... 84 3.6 FwJj 25W: ...... 86 3.6.1 Dates and chronology ...... 86 3.6.2 Local geology and stratigraphy ...... 87 3.6.3 Archaeological assemblage ...... 88

viii 3.6.4 Paleoenvironmental context ...... 89 3.6.5 Other finds ...... 89 3.6 FwJj 25 ...... 93 3.7.1 Dating ...... 93 3.7.2 Local geology and stratigraphy ...... 94 3.7.3 Archaeological assemblage ...... 94 3.7.4 Paleoenvironmental context ...... 95 3.7 FwJj 5 ...... 98 3.8.1 Dating ...... 99 3.8.2 Local geology and stratigraphy ...... 99 3.8.3 Archaeological assemblage ...... 101 3.8.4 Paleoenvironmental context ...... 102 3.8 FwJj 27 ...... 108 3.9.1 Dating ...... 108 3.9.2 Local geology and stratigraphy ...... 109 3.9.3 Archaeological assemblage ...... 109 3.9.4 Paleoenvironmental context ...... 110 CHAPTER FOUR: Faunal Analysis ...... 118 4.1 Introduction ...... 118 4.2 Laboratory and archaeological procedures. ………………………………………………119 4.3 Faunal analysis ...... 119 4.4 Faunal composition from GaJi 4 ...... 123 4.5 Faunal composition at FwJj 25W ...... 130 4.6 Faunal composition at FwJj 25 ...... 136 4.7 Faunal Composition at FwJj 5 ...... 139 4.8 Faunal composition at FwJj 27 ...... 144 4.9 Summary ...... 146 CHAPTER FIVE: Lithic Analysis ...... 148 5.1 Introduction ...... 148 5.2 Lithic artifacts assemblage from GaJi 4 ...... 153 5.3 Lithic artifacts assemblage from FwJj 25W ...... 157 5.4 Lithic artifact assemblage from FwJj 25 ...... 161 5.5 Lithic artifacts assemblage from FwJj 5 ...... 164 5.6 Lithic artifacts assemblage from FwJj 27 ...... 166 5.7 Lithic Artifacts composition and intersite comparison ...... 169 CHAPTER SIX: Analysis of ceramic shards and other assemblages ...... 177 6.1 Introduction ...... 177 6.2 Ceramic assemblage from GaJi 4 ...... 179 6.3 Ceramic assemblage from FwJj 25W ...... 183 6.4 Other finds from FwJj 25W ...... 187 6.5 Ceramic assemblage from FwJj 25 ...... 187 6.6 Ceramic assemblage from FwJj 5 ...... 194 6.7 Conclusion ...... 199 CHAPTER SEVEN: Obsidian survey, sourcing and geochemical characterization...... 202

ix 7.1 Introduction ...... 202 7.2 Obsidian sourcing surveys ...... 202 7.3 Geochemical characterization and analytical procedures used to characterize obsidian ...... 207 7.4 ED-XRF – Laboratory procedures and Instrumentation ...... 208 7.5 Laser Ablation Inductively Mass Spectrometry (LA-ICP-MS) ...... 215 7.6 Results from geochemical characterization ...... 224 7.7 Results from ED-XRF analysis ...... 227 7.8 Results from LA-ICP-MS analysis ...... 251 7.9 Relationship between sources and technology through time ...... 257 CHAPTER EIGHT: Discussions and Implications of Research...... 269 8.1 Introduction………………………………………………………………………………………………269 8.2 Measuring mobility patterns and raw material sourcing………...... 269 8.3 Foragers and the adoption of food production in Lake Turkana Basin ...... 279 8.4 Models for entry and movement of herders in Northern Kenya ...... 282 8.5 Herder adoption in Turkana Basin and elsewhere ...... 284 8.6 Conclusions ...... 292 CHAPTER NINE: Conclusions and Directions for Future Research ...... 294 9.1 Summary ...... 294 9.2 Directions for Future Research ...... 296 Bibliography ...... 305 APPENDICES Curriculum Vitae ...... ……………………326

x LIST OF TABLES

Table 3.1 OSL and radio carbon dates at GaJi 4 ...... 75 Table: 3.2 Stratigraphic descriptions of geological sections at GaJi 4 ...... 76-77 Table 3.3 Stratigraphic distribution of assemblages at GaJi 4 ...... 78 Table 3.4 General assemblage composition at GaJi 4 ...... 79-80 Table 3.5 Inventory of surface collected finds FwJj 25W ...... 90 Table 3.6 A breakdown of the excavated finds at FwJj 25W ...... 91 Table 3.7 A breakdown of the surface collected finds at FwJj 25 ...... 96 Table 3.8 a breakdown of the excavated finds at FwJj 25 ...... 97 Table 3.9 Assemblage composition from surface collection at FwJj 5 ...... 103 Table 3.10 Excavated assemblage at FwJj 5 ...... 104 Table 3.11 Chronology table for FwJj 27 ...... 111 Table 3.12 a and b The Optical Simulated Luminescence dates for sites under investigation ...... 111 Table 4.1Taxonomic representation/NISP distribution at GaJi 4 ...... 126 Table 4.2 Faunal composition from GaJi4 ...... 128 Table 4.3 Inventory of Identifiable Skeleton Elements from FwJj 25W ...... 132-133 Table 4.4: Inventory of mammalian identifiable skeleton elements at FwJj 25W ...... 134 Table 4.5 Inventory of identifiable skeleton elements from FwJj 25 ...... 137 Table 4.6 Faunal composition based on NISP FwJj 25 ...... 138 Table 4.7 Identifiable skeleton elements from FwJj 5 based on NISP ...... 140 Table 4.8 Taxonomic representation of fauna at FwJj 5 based on NISP ...... 141 Table 4.9 Inventory of identifiable (NISP) skeleton elements from FwJj 5 ...... 142 Table 5.1 Raw material percentages for lithics from research sites ...... 154 Table 5.2 Typological composition of stone artifacts assemblage from GaJi 4 ...... 156 Table 5.3 Typological composition of stone artifacts from FwJj 25W ...... 159 Table 5.4 Stratigraphic distribution of raw materials at FwJj 25W ...... 160 Table 5.5 Typological composition for lithic artifacts ...... 162 Figure 5.6 Tool types and lithic raw material distribution from FwJj 25 ...... 163 Table 5.7 Typological and raw material composition at FwJj 5 ...... 165 Table 5.8 Typological and raw material composition at FwJj 27 ...... 168 Table 5.9 Chi-square of raw material types at the archaeological sites studied ...... 172 Table 5.10 Weathering stages for lithic artifacts from research sites ...... 175 Table 6.1 Ceramic decoration motifs at GaJi 4 ...... 181 Table 6.2 Ceramic assemblage recovered from FwJj 25W: ...... 185 Table 6.3 Excavated and surface collected ceramic assemblage from FwJj 25 ...... 191 Table 6.4 Types and temper proportions on ceramic shards ...... 193 Table 6.5 Excavated and surface collected ceramic assemblage from FwJj 5 ...... 197 Tables 7.1 Localities of obsidian geological reference samples ...... 205 Table 7.2 Elemental composition of geological reference samples ...... 234 Table 7.3 Elemental composition of archaeological samples from studied sites ...... 243 Table 7.4 Summary size statistics by site for ED-XRF and LA-ICP-MS samples...... 260

xi LIST OF FIGURES

Figure 1.1 East African fishing, foragers and herder sites...... 35 Figure 2.1 Location of Lake Turkana in Northern Kenya ...... 41 Figure 2.2 Bathymetric map of Lake Turkana ...... 42 Figure 2.3 Outcrop of Tertiary and Quaternary strata at the study area ...... 46 Figure 2.4 Lake Turkana Lake level changes during the Holocene ...... 55 Figure 2.5 Pastoral Neolithic sites and fisher settlements at Turkana Basin ...... 56 Figure 2.6 Location of obsidian sources sampled for this study ...... 61 Figure 3.1 Fisher settlement Pastoral sites at Lake Turkana Basin ...... 65 Figure 3.2 Paleontological collection areas at Koobi Fora ...... 81 Figure 3.3 The stratigraphic sequence of the outcrops at GaJi4 ...... 82 Figure 3.4 Site sampling and excavation at GaJi4 ...... 83 Figure 3.5 Area 10 collections areas at research area ...... 85 Figure.3.6 Stratigraphic section for FwJj 25 complex ...... 92 Figure 3.7 OSL samples taking at FwJj 5 ...... 105 Figure 3.8 Excavation at FwJj 5 modified from Barthelme (1985) ...... 106 Figure.3.9 Stratigraphic section for FwJj 5 ...... 107 Figure 3.10 Lake level changes during the Holocene at Turkana Basin...... 113 Figure 3.11 Stratigraphic section form FwJj 27...... 114 Figure 4.1 Representation of wild and domestic fauna at GaJi 4 ...... 127 Figure 4.2 Taxonomic representation and NISP distribution at GaJi 4 ...... 129 Figure 4.3 Representation for wild, domestic and aquatic fauna at FwJj 25W ...... 135 Figure 4.4 Representation of domestic, wild and aquatic fauna at FwJj 5 ...... 143 Figure 5.1 Raw material percentages for lithic raw materials from all research sites .. 155 Figure 5.2 Raw Material composition of lithic artifacts from site FwJj 25W ...... 158 Figure 5.3 Raw materials composition for lithic artifacts at FwJj 27 ...... 167 Figure 5.4aDistribution of lithic artifact assemblages from research sites ...... 173 Figure 5.4b Distribution of lithic artifact groups from studied sites…………………….…..…174 Figure 6.1 Wall thickness of shards recovered from GaJi 4 ...... 182 Figure 6.2 Wall thickness of shards recovered from FwJj 25W ...... 186 Figure 6.3 Wall thickness of shards recovered from FwJj 25: ...... 192 Figure 6.4 Wall thickness of shards recovered from FwJj 5 ...... 198 Figure 7.1 Obsidian sources sampled for this study ...... 206 Figure 7.2 Schematic representation of ED-XRF machine ...... 214 Figure 7.3 LA-ICP-SM instrumentation setup ...... 219 Figure 7.4 Bivariate plots for zirconium, niobium and yttrium ratios....………………………236 Figure 7.5 Bivariate plot for zirconium and niobium.…………….……………………………………237 Figure 7.6 Elemental composition for archaeological artifacts……………………………………238 Figure 7.7a Bivariate plots of zirconium, niobium and yttrium ratio show Suguta valley being the main source ...... 239 Figure 7.7b ED-XRF, Zr/Y and Zr/Nb two dimensional plots for FwJj 5 artifacts and geological sources...... 240 Figure 7.7c ED-XRF two dimensional plots for Zr/Y and Zr/Nb ratios at Gaji 4...... 241

xii Figure 7.7d ED-XRF two dimensional plots of Zr/Y and Zr/Nb ratios at FwJj 25 ...... 242 Figure 7.7e ED-XRF two dimensional plots for Zr/Y and Zr/Nb for Archaeological and geological sources ...... 247 Figure 7.8 Principal components analysis of trace element chemistry of source samples and artifacts ...... 248 Figure 7.9 Principal Component Analysis of trace element chemistry of source samples and artifacts ...... 249 Figure 7 10 two dimensional of Zr and Zn for artifacts from FwJj 25w ...... 250 Figure 7.11 LA-ICP-MS two dimensional plot of Nb and Ce for obsidian artifacts from archaeological sites...... 256 Figure 7.12a Fall-off curves for geochemical types with distance from site GaJi 4 ...... 261 Figure 7.12b Fall-off curves for geochemical types with distance from site FwJj 25 ..... 262 Figure 7.12c Fall-off curves for geochemical types with distance from site FwJj 25W .. 263 Figure 7.12d Fall-off curves for geochemical types with distance from site FwJj 5 ...... 264 Figure 7.13a Flake length and width versus distance from source for formal tools from GaJi 4 ...... 265 Figure 7.13b Flake length and width versus distance from source for formal tools from FwJj 25 ...... 266 Figure 7.13c Flake length and width versus distance from source for formal tools from FwJj 25W ...... 267 Figure 7.13d Flake length and width versus distance from source for formal tools from FwJj 5 ...... 268 Plate 3.1 Photos of Geological trench at GaJi 4 ...... 115 Plate 3.2 Excavations at FwJj 25W ...... 116 Plate 3.3 Human skeleton remains during excavation at FwJj27 ...... 117 Plate 4.1 Faunal material recovered from FwJj 25W ...... 145 Plate 5.1 Microlithics recovered from FwJj 25W ...... 176 Plate 6.1 Ceramics from study sites ...... 201

xiii 1

CHAPTER ONE

Scientific Frameworks Leading to a Better Understanding of the Earliest Stage

of Pastoralism from Lake Turkana

1.1 Introduction

The Galana Boi Formation, Lake Turkana, Kenya, provides so far the earliest evidence of herding in East Africa and therefore, represents a rare opportunity to study the dynamics of early pastoralist mobility and subsistence lifestyles during periods of increased climatic variability. Against this background of climatic variability and change in the Turkana Basin may have been occupied by population groups that were distinct from most of those described in the African ethnographic record from the colonial period to the present (Blackburn 1974, 1982; Cronk 1989, 2002). Based on a number of archaeological studies (Ambrose 1984; Dale 2007; Dale et al. 2004; Gifford et al. 1980;

Lane 2004; Prendergast 2008;) from other localities in Kenya, it would appear that there was variability in hunter–gatherer and herder mobility and subsistence. These studies indicate that there were different forms of a “delayed-return” economy-an economy system in which not everything that is produced or acquired is not consumed at once, but saved for time of shortages (Woodburn 1980). This type of economy, presents a number of theoretical implications for settlement patterns, subsistence and interaction between food producing groups and hunger-gatherer foraging groups. If such an economic situation could be identified in the archaeological record, it would make the

Galana Boi sites unique in shedding light on the dynamics under which pastoralism was

2 introduced in Sub-Saharan Africa and the subsequent trajectory of food production and the development of nomadic lifestyles.

With these thoughts in mind, I began my investigation of Pastoral Neolithic (PN) assemblages at Koobi Fora on the eastern margins of Lake Turkana, expecting to find evidence for a highly specialized, probably delayed-return foraging or herding economy.

But as my studies progressed, the data proved to be much more complex. The data shows great variation in subsistence strategies. The assemblages from PN sites in the

Lake Turkana Basin indicate that the occupants were not only herders, but also consumers of wild and aquatic food resources. At sites FwJj 5, FwJj 25, FwJj 25W at

Ileret and site GaJi 2 and 4 at Koobi Fora, PN ceramics were recovered in a stratigraphic association with wild and domestic faunal assemblages (Barthelme 1981, 1985; Ndiema et al. 2010, In press). This raises an important theoretical question. When one finds evidence of wild and domestic taxa together, with material culture that is traditionally associated with either foragers or herders, or both, how does one interpret such as a site? Although there is no easy answer to this question, below I describe several modern day situations that can be used to build models of forager-food producer interactions, and to determine possible indicators of such interactions in the Holocene archaeological record at Koobi Fora.

1.2 Hunter-gatherer economic strategies and social organization

Beginning in the nineteenth century and increasing steadily through the twentieth century, explorers, missionaries, colonial administrators, and eventually, trained ethnographers documented a wide variety of hunting, gathering and fishing societies across the world. The majority of which were recorded at low (tropical) latitudes (Binford 1982). Much variation in economic strategies has been observed in these records, and most strikingly, between foragers at tropical latitudes and those at temperate latitudes. Variation in economic strategies has been observed to affect many other aspects of settlement, social relations, and hierarchy. Anthropologists have developed many binary categories to account for such differences among hunter- gatherers, both present and past. There categories include simple versus complex

(Arnold 1996; Hayden 1990), egalitarian versus nonegalitarian (Kelly 1992), foragers versus collectors (Binford 1980), generalized versus specialized (Price and Brown 1985), nonstoring versus storing (Testart 1982), and immediate-return versus delayed return

(Woodburn 1979, 1980, 1982, 1988). While all of these contrasting pairs are closely linked, this study focuses on Woodburn’s model for immediate- and delayed-return systems, since this has recently been applied in East Africa (Dale 2007; Dale et al. 2004;

Prendergast 2008; Lane 2004; Ndiema et al. 2010).

Drawing on the ethnographic literature and his research among the Hadza of northern Tanzania, Woodburn (1980) defines an immediate-return system as one in which food is consumed as soon as it is obtained; (a) economic activities are focused on the present moment, (b) private property or valued assets are nonexistent, (c) and tools

4 or weapons are disposable, transportable, and do not require large investments of labor. Delayed-return systems, by contrast, involve substantially more investment since economic activities focus on past, present and future. For example, food may be stored or preserved (e.g., through drying, smoking, salting or freezing) for future consumption; and wild food sources (e.g., beehives, plant stands, stored grain, or female animals) may be protected or tended to ensure future yields. Woodburn (1982) argues that delayed- return foragers involve four main types of “valued assets:”

a. “Technical facilities” such as fishing boats, nets, and stockades for game animals

and beehives;

b. Processed and stored food; and

c. Wild food sources that are deliberately tended, well-looked-after or increased

d. Male rights over female relatives as resources to be married off.

Woodburn (1980, 1982) further argues that the two different systems correspond to distinct (though internally variable) types of social organization. Immediate-return hunter gatherers such as the Hadza should all dependent relationships by remaining autonomous, and they are egalitarian, having equal access to food and the technology required to obtain it (Marlowe 2010 Woodburn 1982). This is reflected in:

a. Subsistence strategies: Immediate-return foragers like the Hadza consume much

of what they procure on the spot, bringing back and sharing only the excess;

large excesses are simply discarded. Some other immediate-return foragers

place more emphasis on food sharing (Woodburn 1982).

b. Settlement patterns: camps occupied by immediate-return foragers tend to be

small and briefly occupied (especially during the wet season), with few or no

permanent structures and sparse material remains (Yellen 1976).

c. Group relations: groups are leaderless; individuals may move in and out of

camps without group consensus. Women are more independent to marry and

divorce as they wish than in delayed-return societies. The sick, injured and dying

are often abandoned, since individuals shun obligations (Woodburn 1979).

By contrast, delayed-return societies have significantly more load-bearing relationships

(Woodburn 1988), i.e., more obligations and interdependence among individuals. This may be reflected in:

a. Subsistence strategies: one defers immediate gratification for greater yields later

i.e. longer term effects of food availability.

b. Settlement patterns: camps are larger and are occupied longer, and may have

structures that require labor (e.g., storage facilities and other architectural

features).

c. Group relations: there are typically leaders and status/wealth differentiation;

female offspring are often treated as valuable assets; there is care for the sick,

injured and dying.

Examples of historic or contemporary delayed-return foragers include the Inuit from the

Arctic region (Smith 1991), the Okiek and the Mukogodo, the only living delayed-return foragers in Kenya (Blackburn 1974, 1982; Cronk 1989, 2002). Given the high degree of

6 investment they require, why do delayed-return systems exist? Since the answer has implications for the origins of food production (the most extreme form of delayed- return system), this question is the subject of heated debate. Those who argue for aspects of climate change, increasing population density, reduced mobility, and consequent “pressure,” leading to resource unpredictability and stress (Cohen 1977;

Keeley 1988; Kelly 1992); and extreme latitude and related seasonality and/or unpredictability of resources (Keeley 1995; Testart 1982). In contrast “pull” theories include variables such as specialization (Aikens and Akazawa 1996) or competition

(Hayden 1990) in attractive settings of abundant, predictable resources.

Woodburn (1980) rejects the primacy of environmental factors in the development of delayed-return systems, contending that immediate- or delayed-return systems can exist in any environment. Nevertheless, it is reasonable to expect that delayed return systems might emerge where there is a seasonal abundance of a highly valued food source (e.g. salmon in the Pacific Northwest, marine mammals in the Arctic). Targeting resources available only in specific seasons often leads to storage, especially at extreme latitudes (Keeley 1995; Testart 1982). Latitude-based theories, however, are influenced by the fact that our sample of delayed-return systems is biased towards temperate regions, with a few exceptions, e.g., in Florida (Marquardt 1986; Widmer 1988) and

Colombia (Oyuela- Caycedo 1996; Stahl and Oyuela-Caycedo 2007). Therefore, some of the ecological causes of the shift to food production in equatorial regions are not fully understood and have to be tested fully in the archaeological record.

1.3 Applying models of hunter-gatherer societies to the past

Woodburn’s model raises several concerns for the archaeologist. First, he proposes that many more delayed-return hunter-gatherers existed in the past than do today, but that the historical and archaeological records remain too patchy to substantiate this claim, especially in East Africa (Woodburn 1980, 1988). Like the ethnographic examples, archaeological data on delayed-return hunter-gatherers come primarily from temperate latitudes (Binford 1982). In Africa, early sedentism or reduced mobility has been suggested for fisher-hunter-gatherers in the Upper Nile Valley of central-north Sudan, and for hunter-gatherers in southwestern Libya, two areas at the margins of the tropics (Caneva et al. 1993; Garcea 2004, 2006; Haaland 1992, 1995,

1997). No prehistoric delayed-return foragers had been reported in sub-Saharan Africa until recent wave of research on the Lake Victoria Basin and Northern Tanzania (Dale

2007; Prendergast 2008; Lane et al. 2007), perhaps because there has not been much research at early to mid-Holocene foraging sites. The weakness of the African record is particularly appalling since as firstly, Africa has more tropical land than any other continent and could contribute much to the global development of hunter-gatherer theory in tropical zones. Secondly, many models of prehistoric hunter-gatherer societies have been formulated in Africa, mainly based on the immediate-return systems such as those of the Hadza, Ju/’hoansi and Mbuti (Yellen 1998; Schrire 1992). This narrow modern sample likely differs from the past, so it is the task of the archaeologist to reconstruct the diversity of African hunter-gatherer lifeways prior to the expansion of food production. Although Woodburn (1980:114) unequivocally specified that he never

8 meant his model to be taken as yet another naive binary classification, it has been interpreted as such in archaeological discourse (Kusimba 2005). This may be due to the fact that the examples we have are fairly extreme, jumping from Pleistocene and

Holocene immediate-return foragers to late Holocene delayed-return foragers.

There are well-entrenched social hierarchies reflected in mortuary practices, large permanent structures, material wealth, and extensive trade in exotic goods (e.g., on the Northwest Coast); these very complex foragers are the most archaeologically visible. Woodburn (1980) argues that hunting and gathering societies are not arranged on a continuum, but tend to cluster at one or the other end. However, he adds that within both delayed- and immediate-return systems, a whole range of aspects of the economy and the social organization are congruent. This is the missing element in most discourses and thus the range of variation within delayed-return systems needs to be explored.

Dale and others (Dale et al. 2004; Dale 2007) take a more nuanced approach to

African hunter-gatherer studies, drawing on ethnoarchaeological data from the Okiek, who forage primarily for honey in the Mau Escarpment in the Kenyan Central Rift Valley.

The authors propose an “ownership model,” which emphasizes the proprietary aspects of Woodburn’s delayed-return model: i.e., such foragers tend to hold certain valued assets, in this case territories, manufactured hives, ownership of traps, and the rights to hang the hives in specific trees (Dale et al. 2004). The Okiek also build houses (used according to the honey-collection schedule) where they cache material objects such as ceramics, leather pouches, and constructed hives (Blackburn 1974, 1982; Smith 1991).

This differs from immediate-return camps, where site reuse and material accumulations are infrequent and unsystematic (Brooks and Yellen 1987; Kent 1987; Yellen 1976).

Additionally, Okiek social organization is characterized by a number of traits that distinguish it from that of immediate-return hunter-gatherers, including some gender inequality, concepts of ownership, and age sets, reflecting an elaborated social structure

(Dale et al.. 2004). But unlike Woodburn’s model, Okiek’s system is also characterized by the absence of many traits of more extreme delayed-return societies (e.g., those of the historic Pacific Northwest). In this example there are no large sites or permanent structures; no exotic trade items or rich material culture; nor specialized trash middens.

Dale et al. (2004) developed a list of archaeologically visible signatures of a moderate delayed-return system and then applied this model, on the whole quite successfully, to foragers’ archaeological data from northern Tanzania (Dale 2007). However, there is no conclusive support (negative or positive) for the ownership model in the faunal data that Dale (2007) presents from Siror, the main hunter-gatherer site studied, whose fauna was analyzed by Cain (2001).

The faunal analysis of several Holocene sites assemblages in this study indicates a likelihood of a diversified economy, at least in terms of domestic stock. This strategy which may have involved a delayed-return system of preservation, storage, and perhaps of semi-sedentism as is practiced today by particular communities resident in Turkana

Basin (Kiura 2005, 2008). However, the situation is complicated by the possibility of interaction with pastoralists or hunter-gatherers. In the Lake Turkana Basin, mid

Holocene Pastoral Neolithic assemblages become more scattered and their meaning

10 increasingly unclear. Therefore, I also address some models for interactions between foragers and food producers based on ethnographic data (Kiura 2005; 2008; Mutundu

1998; Prendergast 2008) which have been used to interpret the archaeological record.

1.4 Forager-food producer interactions in the past and present

According to the ownership model, the identification of moderate delayed- return foragers rests on the repeated use of sites, rich deposits of material culture, and the presence of storage vessels (Dale et al. 2004; Mutundu 1998). These traits would equally identify a camp occupied by pastoralists, albeit with some other expected features (e.g., remains of domestic animals, evidence of enclosures, and/or more permanent architecture). What if there is a mixed signal, for example with both wild and domestic fauna and rich material remains? To develop archaeological expectations, I draw on models for both modern and prehistoric forager-food producer interactions.

Many archaeological data come from prehistoric or historic frontier situations in Europe,

Americas, Japan, and the South Pacific (Spriggs 1996; Zvelebil 1996). Alexander (1977,

1984) built a model for Europe and later applied it to southern Africa. The ethnographic record includes examples from Inuit and Australian Aborigines, who took up food production under the influence of Europeans; and there are very rich ethnographic and prehistoric records for southern Africa (Brooks et al. 1984; Kent 2002; Robbins et al.

2005; Sadr 2003; Smith et al. 1991; Thorp 1997; Yellen 1984), and ethnohistoric data from East Africa (Cronk 1989; Kiura 2008; Mutundu 1998) see also Schrire (1992) for

11 contra view. Considering these examples together, the records of forager-food producer contact are highly variable.

In Alexander’s (1977, 1984) model for a “moving frontier” between foraging and food producing groups, recently applied to East Africa (Lane 2004), foragers are eventually completely subsumed and/or isolated by food producers, with the latter group assumed to be dominant. Foragers are thus predicted to change, while food producers impose their unchanged way of life. While this model applies well to the data from elsewhere, the evidence from East Africa suggests that this may not always be the case. Gifford- Gonzalez (1998, 2000) has argued that herders moving into new, higher- risk environments may have been forced into relationships with local foragers that were on equal terms, or even with foragers in a position of power. This is because foragers possessed intimate knowledge of the landscape, climate and resources.

However, major changes can and have taken place when food producers and foragers come into contact. A study of economic changes among the !Kung San or bushman of the Kalahari and the Mukogodo of the north-central Kenya, that took place place over just three decades, provides an example that could be applicable to prehistoric situations (Brooks et al. 1984; Cronk 1989; Yellen 1984). Influenced by neighboring farmers and pastoralists and government officials during the second and third quarter of the 19th century, the !Kung and the Mukogodo began to acquire “exotic’ items such as livestock and money from remittances for those engaged elsewhere in work for wages. This resulted in settlement patterns, diets, and social relations distinct

12 from those first described by Lee (1968, 1979), Kenya Land Commission (1934), and quoted in Cronk 1989).

A similar situation took place in the Congo Basin, where Aka Pygmies developed increasingly strong ties to non-foragers, beginning with small-scale trade in game meat, escalating in the 1950s to large-scale trade in ivory, pelts, palm nuts and rubber, and eventually to employment on coffee plantations in the 1960s. The changes observed by

Bahuchet and Guillaume (1982) are similar to those noted above: increased material wealth (especially in nontraditional goods), less mobility, fewer wild foods eaten, and more dependent relationships amongst each other and with outsiders. Similar changes may have taken place among hunter-gatherers in the past, and this relates to one of the most heated debates in African anthropological archaeology. On one hand are the

“revisionists” (Wilmsen 1989; Wilmsen and Denbow 1990) who argue that the relationship between food producers and foragers was dominated by local agro- pastoralists. On the other hand there are those who argue that hunter-gatherers (! Kung for example) have largely maintained their autonomy and identity as hunter-gatherers

(Solway and Lee 1990).

Although the revisionists are right to see forager history as nuanced and complex, the other side correctly argues that material remains of a food-producing culture in a forager site do not necessarily mean encapsulation, assimilation and/or servitude. Furthermore, some aspects of the foraging lifestyle can be observed in a group that is currently hunting and gathering, regardless of their history (Blackburn

1982). Clearly and narrowly defined relational analogies (Wylie 1985) should be

13 applicable to a foraging group regardless of history, as Marlowe (2010) and Marshall

(2005) argue. This is especially true when analogies focus on functional rather than social questions, since variations in activities such as hunting, butchering, or building a shelter may be more constrained by practical concerns than by cultural choices. The intensity of the Kalahari debate reflects the important stature hunter-gatherers have in anthropological archaeology, and the degree to which we depend on ethnographic analogy to interpret archaeological sites. It also suggests that forager-food producer interactions are complex and are not necessarily unidirectional (as the “moving frontier” model implies). For example, foragers are not always destined to become food producers and vice versa and may only do so on a situational basis (Schrire 1992). For alternative view see (Cronk 1989, 1991, and 2004). Finally, the debate suggests that interpreting archaeological evidence for identity is always complicated, whether this identity is economic (forager versus food producer) or social (ethnic, linguistic, or gender differences).

This study focuses on obsidian sourcing and characterization to model changes of mobility patterns, and leaves the much complicated question of ethnic or linguistic identity for others to handle. In eastern and southern Africa, linguistic data are mainly the domain of Ehret (1982, 1984, and 2002). Disentangling foragers from food producers in the archaeological record is challenging enough on its own. The research in northern Kenya indicates that relying on fauna, ceramics or lithics assemblages alone is risky, and that patterns of raw material procurement such as obsidian sourcing and characterization may tell a different story. The difference between hunter-gatherers and

14 herders could be a matter of ecological shifts than strong cultural distinctions. The debate in southern Africa on how to differentiate herders’ and foragers in the archaeological record is the case in point (Schrire 1992; Smith et al. 1991).

Over the last 25 years archaeologists have developed a number of theoretical models to explain and predict the composition of lithic assemblages based on both basic economic principles and analogies to ethnographic examples. Building on foundational work by Binford (1979) and Renfrew (1977), a common theme running through these models examines the interplay between mobility patterns and stone tool acquisition

(Brantingham 2003, 2006; Kelly 1992; Kuhn 1989)

In these models, groups practicing different degrees of mobility such as hunting and gathering versus a herding group that performs various activities. They deplete and replenish their supply of stone tools in a patterned manner, leading to the deposition of structured assemblages of artifacts of different types, sizes, and raw materials (Carr

1995). A basic distinction within many models concerns the acquisition and use of stone tools by these groups suggests that foragers referred to as “residentially mobile”

(Binford 1969; Eerkens et al. 2007). These groups often acquire stone tools directly by embedding raw material extraction within other subsistence activities and transport such materials to places where they are needed (Ambrose and Lorenzo 1990). Spent and broken tools are discarded and replaced with new ones as groups encounter new resources of raw material on the landscape. By contrast, less mobile populations often either directly procure or make use of inferior and locally- available materials or acquire higher quality raw materials indirectly through trade. However, stone tool access for

15 stable populations may be tempered by the degree of logistical mobility, where greater distances covered during logistical trips may allow knappers to directly access a more steady supply and a greater range of non-local and/or higher quality materials (Binford

1979, 1980).

Dyson-Hudson and Smith (1978) and Wilmsen (1989) provide a compelling argument on ecological based variation in socio-territorial organization and exchange among hunter-gatherers that can serve as a model for selection on behavior driven by environmental variability and stability. Such studies show that when primary productivity is high and resources are predictable and dense, as in the warm humid early Holocene the hunter-gatherers have small defended home ranges and reduced intergroup interactions including infrequent exchange of material culture and information (de Menocal et.al 2008). Conversely when primary productivity and predictability declines as in arid environments and climates, hunter gatherers home ranges should expand, territorial defense should relax and intergroup exchange including material and information exchange should increase (Ambrose and Lorenz

1990). The Kalahari Band clusters exemplify this strategy of “co-operative risk minimization” (Kent 1993; Winterhalder 1996)

1.5 Aspects of obsidian sourcing, ceramic, and faunal analysis and problems of convergence or equifinality

Long distance exchange is, a fundamentally important feature of modern human behavior (McBrearty and Brooks 2000). Lithic source exploitation patterns can monitor the intensity of extra territorial interactions and should differ substantially between societies with closed versus open territories or residentially mobile and highly mobile groups. Lithic raw material transported more than 40km from its source are considered exotic reflecting inter-group social networks (Eerkens 2007). The abundance and distinctive composition of obsidian sources in Lake Turkana Basin makes the region an ideal place to test social ecological models and the role of regional social networks in the evolution of managed food production.

Distance decay or fall-off curves (Blumenschine et al. 2008; Renfrew 1977;

Torrence 1986) of lithic sources at different distances from sites and percentages of obsidian at different distances from the source are effective tools for assessing socio- territorial organization and regional interaction. Using data from long term study of raw materials in southern France, Wilson (2007) presented models which she argued were useful for determining source “attractiveness” (Wilson 2007: 389) using geologic/geographical variables. Where as Wilson’s (2007) model may be applicable to

East Africa to test site suitability, the amount of data required to assess such a model is currently lacking in East Africa. However Wilson’s (2007) quantitative models of interaction spacing behavior and band organization can still be applied and expressed as distance-decay curves. If territories are small and boundaries are defended with limited

17 territorial interaction, then the cut-off in the distance-decay curve should occur closer to the site. A gradual decline over longer distances especially spanning several home ranges may indicate down-the-line exchange between individuals across the territorial boundaries. As inter territorial exchange networks intensify and diversify, the decline with distance should become more gradual and the diversity of sources should increase.

Graphs of Early and the mid Holocene lithic procurement strategies support the above lithic procurement models of Latter Stone Age (Ambrose, 2001b). Obsidian sources are wide spread in Kenya and this makes it possible to construct site-to-source distance decay graphs. However previous studies only provide relatively low resolution curves (Merrick and Brown 1994; Merrick et al. 1994). There was need to analyze more sources and archaeological artifacts in order to create accurate boundaries of within home range supply zone procurement. This is necessary to test hypothesis of range expansion and construction in response to climatic changes and to accurately measure the intensity of macro-regional network interactions. Brantingham (2006), Eerkens

(2007) and Wilson (2007), have all argued that distance decay graphs provide coarse- grained insights into prehistoric behavioral patterns. This study increases the resolution with which to approach distance decay-curves by analyzing large assemblages from sites at different distances from source. Source diversity and distance decay patterns may be biased by artifact assemblages’ composition, raw material quality and sampling strategies (Eerkens et al. 2008). Curated artifacts and micro debitage may include even more distant sources and nearby sources of poor quality may be used expediently to produce large minimally retouched flakes.

At Ngamuriaka, a Pastoral Neolithic site at south western Kenya, one source of obsidian artifact accounted for 26% of large artifacts, but only 4% of the micro debitage

(Merrick et al. 1994).

For the interpretation of faunal material, This study looked at previous research detailing the faunal composition of the archaeological record in regards to distinctive features of faunal assemblages created by foragers versus food-producers. Specifically, research such as Mutundu’s (1998) ethnoarchaeological research with the Mukogodo

(Laikipia County, Kenya) also at Prendergast’s (2008) research among the Kansyore foragers in Lake Victoria Basin are relevant. Both Mutundu and Prendergast argue that aside from the most obvious potential indicator, the ratio of wild to domestic taxa, each group of fauna must be examined in greater detail. Within the wild assemblage, ratio of ungulates to non-ungulates is informative. Based on modern forager societies, non- ungulates such as tortoise, lizard, primates, and rodents are often consumed, whereas these are frequently taboo in pastoralist societies (Marshall and Stewart 1995).

Therefore, pastoralists hunting to diversify their subsistence base would be less likely to have such animals in their food remains.

Within the domestic faunal assemblage, two indicators might suggest whether domestic taxa are the result of incidental acquisitions or are an integral part of the site’s economy. First, age and sex data are examined in an attempt to estimate the herd structure. A number of ethnographic accounts ( Dahl and Hjort 1978; Meadows and

White 1979) have shown that pastoralists manage their herds by selectively culling animals; in herds raised for both meat and milk, this will often mean culling young males

19 and keeping females for breeding and milk production. This should be reflected in a high proportion of juvenile males, and few young females, in an archaeological assemblage.

Unfortunately determination of age, and particularly of sex, is difficult and requires a large assemblage and good reference data. In this study age determination on domestic taxa, was determined by tooth eruption/wear and epiphyseal fusion (see Chapter 4). A second noteworthy feature of domestic assemblages may be the ratio of small stock

(caprines) to large stock (cattle), since several scholars have suggested that foragers will

“experiment” first with small stock, since they breed more quickly, are easier to tend, and may be easier to acquire (Gifford-Gonzalez 1984; Marshall 1986; Mutundu 1999).

More established herds, managed by full-time pastoralists, would be expected to have higher numbers of cattle; but as Marshall (1986) points out, ratios of caprines to cattle are highly variable in modern pastoralist societies, and caprines reproduce and die more quickly than cattle and thus tend to form a larger part of the death assemblage. This ratio is therefore imperfect, but as I show in subsequent chapters, caprines dominate all of the sites that I interpret as being either on the threshold to pastoralism, or as mixed assemblages created by herding foragers or foraging herders.

Another indicator that is used to decipher the mobility of the prehistoric population in this study is pottery. Pottery is one of the most important sources for archaeological data in archaeological studies. Worldwide, ceramic decorative motifs, morphological and technical similarities and differences are used to model prehistoric mobility patterns not only because of its ability to provide chronological and chorological classification, but also because of the abundance of information about

20 many other aspects of prehistoric lifeways such as exchange and social interactions

(Sadr 1998; Huffman 1989; Keding 2000). Various streams of Bantu migrations in East

Africa for example have been reconstructed on the basis of ceramic evidence (Chami

2007; Chami and Kwekason 2003; Hanotte et al. 2002; Sutton 1990). In South Africa,

Bantu migration has equally been used to investigate the introduction of herding and food production (Huffman 1989; Russell 2004). In order to understand the nature and character of the ceramic assemblage ceramic assemblages were, recorded and analyzed and their context in each horizon with an emphasis on technological attributes namely, temper firing, finishing and decoration, vessel form and wall thickness. These data attributes were later critical in documenting differences in mobility patterns (see

Chapter 6). Overall, although ceramics traditions such as Nderit ware and their distribution seem to provide a valid marker for tracing headers’ mobility in the archaeological record, inadequate samples from the PN sites at the Turkana Basin prevent a thorough investigation of their mobility patterns following the introduction of domestic stock in Lake Turkana Basin. Consequently, the documentation of chronological changes in both obsidian use and ceramic traditions with different physical and contextual visibility were essential for the identification of major economic transformation points in Lake Turkana Basin. For the cultural changes under investigation, it means that in the case of migration, changes in technological as well as decorative styles are predicted. In the case of in-situ shift in subsistence, change in decoration was predicted. While technological changes, would only occur if they are accompanied by clear functional advantages. If Carr’s (1995a) model on artifact design is

21 valid, technological attributes and decoration features should provide qualitative differentiated information that has both chronological and spatial implications.

Pottery bears enduring cultural makers which become established long before food production. Pottery is a good source of information for examining the discrete functions of social differentiation and is important to understanding the larger anthropological questions relating to exchange and mobility patterns among herders and foragers. At first glance pronounced technological and stylistic diversity will argue strongly against an abrupt inception of pottery. If the observed diversity in ceramic traditions were brought by incoming settlers then there should be a concomitant disjunction on other aspects of the archaeological record such as selection of obsidian sources and specific use of faunal resources.

None of these indicators are flawless, but they do offer some means of assessing mixed assemblages in archaeological contexts where both foragers and food producers may have been agents. Moreover, they underscore the complexity of differentiating economic identities in the archaeological record, and as the ethnographic data discussed above which show that, these sometimes may not be distinguishable at all.

1.6 Research goal and hypotheses

Dr. John Barthelme’s pioneering studies in the 1970’s established the antiquity of pastoralism in East Africa in the Turkana Basin (Barthelme 1981, 1985). However the nature and mode of that shift from hunter-gatherer to pastoralist subsistence is still not

22 clear (Ambrose 1984; Bower 1988; Gifford-Gonzalez 2003; Marshall 1990). There are several possible scenarios with which a group can change its substance system. This project used multi-faceted approach to investigate cultural changes among communities living in the Lake Turkana Basin, northern Kenya during the early to mid-Holocene

(9000-3500BP). The aim of this project is to model changes in mobility patterns following the inception of domestic stock in the eastern Turkana Basin. This project was part of an ongoing multidisciplinary Holocene research project. Thus, complimentary data from independent lines of evidence including changes in ceramic traditions

(collaborations with Dr. Keding) analysis of lithic artifacts (collaboration with Dr Harris), obsidian sourcing (collaboration with Dr Dillian) paleoenvironmental reconstruction

(collaboration with Dr Ashley) and faunal assemblages (collaboration with Dr Marshall) was important components in the long term conclusions made in this study.

The immediate objectives of this dissertation were to test these hypothetical scenarios.

The primary method that used is to:

1. Develop a high resolution database for obsidian artifacts and source

chemical composition in East Turkana Basin using Laser Ablation

Inductively Coupled Mass Spectrometry (LA-ICP-MS) and Energy

Dispersive X-ray Florescence (ED-XRF).

2. Document changes in mobility patterns of hunter-gatherers/ fishers and

early pastoralists using geochemical composition of obsidian

archaeological specimens. I investigated the test implications of the

proposed scenarios by developing and analyzing a comprehensive

database of obsidian raw material sources, geochemical fingerprinting of

these sources, and similar analysis of obsidian artifacts.

3. To combine the obsidian data with other independent lines of evidence

from artifact (ceramics and lithics) analyses and faunal data.

4. Determine reliable the chronology of the sites under investigation

As subsistence strategies changed so did the movements of people across the ancient landscape (Glascock 2002; Bugoi et al. 2004; Shackley 2005). Anthony (1990) demonstrated that changes in mobility patterns tend to act in a broadly predictable manner. For example, a population would continue to use familiar resources such as obsidian regardless of the increased transport costs (Silliman 2000; 2005) until they become more aware of locally available resources. Therefore, the appearance of distant obsidian sources in archaeological assemblages may represent a highly mobile population. If native populations gradually changed their subsistence strategy to include pastoralism, then a bimodal distribution of both exotic and local obsidian would be expected at the early pastoralist sites. In contrast the greater mobility required of hunter-gatherer populations depending on resource availability and predictability would result in more intensively reduced lithic industries and changes in discard decisions at the early Holocene sites (Ambrose and Lorenz 1990; Bousman 2005). The alternative hypothesis is that new populations moved into Turkana Basin bringing domestic stock and exotic obsidian. If this was the case one would predict a high percentage of extra- local obsidian at early Holocene sites, whereas indigenous fisher hunter-gatherer sites

(my baseline of obsidian use by indigenous people) would exhibit a higher representation of local obsidian. Therefore one would expect specific ceramic traditions to appear together as a package at sites dating to around 4500-4000BP and a stylistic similarity that links the earliest pottery to external sources recovered from areas further north (Keding 2000,).

1.7 Summary; Goals of research and organization for thesis

To summarize, two pronounced tasks lie ahead: first, to determine the mobility patterns that existed in the past during the early to mid Holocene; and second, to assess the scale of interaction between early to mid Holocene foragers with food producers.

We know from the substantial Kenyan archaeological record, that in the Lake Turkana

Basin, domestic stock begin to appear in archaeological record by at least 4000 BP, and spread southwards gradually ca. 4000-2000 BP. The question however is to what extent did herding initially impact foraging populations? Studies in the Central Rift Valley at

Enkapune ya Muto and other Eburran sites (Ambrose 1984, 1998; Gifford et al. 1980), in

Lake Victoria Basin in Western Kenya (Dale 2007; Dale et al. 2004; Lane et al. 2007;

Munene 2002), and at Lake Eyasi in Northern Tanzania (Marshall 1986; Prendergast

2008) suggest at least in this area, the transition from foraging to food producing was gradual and was made by local hunter-gatherers, rather than through a major population movement (Ambrose 1984a,b, 1998; Dale et al. 2004; Dale 2007; Lane 2004;

Lane et al. 2007; Prendergast 2008). In the study area (Lake Turkana) there is a paucity

25 of current literature on this subject. The extent to which foragers interacted with (or became) food producers is based on limited data from previously excavated sites. Lack of thick well-stratified sites makes Lake Turkana a fascinating, but archaeologically complex, location to investigate changes in mobility patterns that culminated to the inception of food production.

1.8 Cultural historic Framework

This section provides a brief outline of Kenya’s latter archaeological sequence.

Information regarding assemblages and the significance of important later Stone Age

(LSA) archaeological cultures is summarized.

1.9 Early/ Later Stone Age occupations

The Later Stone Age (LSA) spans the period ca. 40,000-2000 BP, these dates have currently been contested (Ambrose 1998; Bower 1991) the former being pushed back and the latter variable depending on local transitions to managed food production. LSA foragers are usually depicted as small, highly mobile groups with immediate-return economic systems (Woodburn 1979; 1980). Evidence of stratified LSA occupation have been reported at Enkapune ya Muto (EYM), at the Central Kenyan Rift Valley dated at

40,00 years (Ambrose 1984a,b, 1998; Marean 1992) and Shurumai rock shelter in the

Laikipia plateau dated at 4300 years BP (Gang 2001; Mutundu 1998), Early latter Stone

Age sites include GvJm 16 at Lukenya Hill (Kusimba 1999, 2002). LSA assemblages are typified by preference for cryptocrystalline silica raw materials such as chert, as well as obsidian. The need for fine quality raw materials might have been satisfied through long distance procurement of raw materials either through exchange or direct procurement.

The resulting toolkit is characterized by increased reduction and standardization of tool assemblage including backed and a microlithic industry. In addition, evidence for use of aquatic and wild ungulates food resources, as well as domesticated animals. Finally an assortment of nonutilitarian tools such as ostrich or stone beads, ocher, and rock art were recovered from LSA sites.

1.10 Early pottery cultures

Leakey (1931) presented the first evidence of ceramics in East Africa based on his excavations at Gamble’s Cave in the Kenyan Rift Valley. These shards could be as old as c. 8000-8500 BP, old although these dates have not been accepted by the archaeological community because the stratigraphic integrity of the sites is suspect

(Bower and Nelson 1978). Sites from Lake Turkana Basin provide evidence of bone harpoons for fishing, sparse occurrences of pottery, abundant fish remains, and some wild terrestrial fauna. Examples of sites with bone harpoons include, Lothagam,

Lowasera, and several sites at the northeastern shores of Lake Turkana dating to ca.

9000-4000 BP (Barthelme 1981, 1985; Kiura 2005; Philipson 1977a; Robbins 1972, 1984,

2006). It is however, important to note that all of the dates from Lake Turkana Basin

27 were obtained using bone apatite or shells, which are less reliable than charcoal or bone collagen (Koch et al. 1997); bone apatite is easily contaminated by ground water carbonates. Dates from bone apatite should therefore be used with caution. Recent research at hunter-gatherer sites in the Lake Victoria Basin (Dale et al. 2004; Dale 2007;

Prendergast and Lane 2010; Lane et al. 2007), have recovered ceramics that could be contemporaneous with those from Lake Turkana Basin. At Lake Turkana Basin, the early

(9300BP) ceramic sites are located at the high lake stand when the lake is thought have transgressed during the early Holocene wet phase (Butzer 1980; Harvey and Grove

1982; Olago et al. 2009; Owen and Renault 1983).

There is an ongoing debate on whether so called “fishing sites” represent diversification in subsistence practices that take advantage of seasonal resources

(Prendergast and Lane 2010; Lane et al. 2007; Robbins 2006) or a distinct cultural group that Sutton (1974; 1977) referred to as “aqualithitic civilization”. Whereas Sutton’s arguments on “aqualithic civilizations” may have had points worthy considering (Dale

2007), it has strongly been contested on the grounds that the “aqualithic” theory could not be substantiated with empirical evidence (Close 1995; Philipson 1977b, 1993;

Robertshaw 1991; Stewart 1989). The decorative, stylistic and technological similarities between the early Holocene ceramic assemblages in Lake Turkana Basin and those from northern Africa have been suggested (Prendergast 2008).

1.11 The Pastoral Neolithic and the spread of pastoralism

The Neolithic in East Africa, is also known as the Pastoral Neolithic (PN) (Bower

1977; Nelson 1993; Wandiba 1980). It is more specifically defined by the appearance of managed food production of mainly domesticated cattle and frequently indistinguishable Ovis aries (sheep) and Capra hircus (goat). It is also marked by the development of regional ceramic traditions, some of which remain poorly defined, and all of which have been the subject of numerous anthropological discussions (Ambrose

1984a, b, 1998, 2001; Bower 1988, 1991; Collett and Robertshaw 1980; Dale 2007;

Gifford-Gonzalez 1998; Robertshaw 1991; Wandiba 1980, 1990).

In Eastern Africa trajectories of food production, including change in subsistence strategies and resource intensification differ from global patterns in that people used pottery before the use of crops.The earliest domesticates in East Africa are thought to be caprines, which were domesticated in Southwest Asia and introduced from North Africa ca. 5000 BP (Barnard 2007; Smith 1992; Kusimba 2003). Cattle do not appear until later, and their origins are less clear (reviews in Gifford-Gonzalez 1998,

2005; Marshall 1998, 2000). There is genetic (Bradley et al. 1998) and morphological

(Caneva 1993; 1984; Grigson 1991; Wendorf et al. 1987) evidence for an independent domestication of wild cattle (Bos primigenius) in North Africa possibly as early as 9000

BP, later followed by hybridizations with South Asian zebu (Bos indicus) and Southwest

Asian cattle (Bos taurus). However, Marshall (1998) argues that this early date needs

29 better archaeological support, for example, in the form of well-dated faunal remains or evidence of stock enclosures.

Neolithic technology is a continuation of LSA microlithic industries, and includes the savanna Pastoral Neolithic, Elmenteitan, and Eburran Phase 5 traditions (Ambrose

2001a, b; Bower 1991; Nelson 1993). According to micromorphological studies, pastoral settlements likely resembled those of modern pastoralists, with accumulations of animal dung and possible confining areas (Shahack-Gross et al. 2003). Cairn-marked burial sites are also common, and these often contain stone bowls, ochre-stained grindstones, and polished pestles (Ambrose 2001b). Faunal assemblages are usually dominated by remains of domestic cattle and caprines, but at some sites with Neolithic occupations, such as from Central Rift Valley and Lake Victoria Basin, and the Laikipia plateau, wild fauna continue to comprise an important part of the diet (Gifford et al.

1980; Marshall and Stewart 1995; Mutundu 1998; Onyango-Abuje 1977; Siiriainen

1984). These faunal data are discussed in detail in next Chapters.

Although wild members of the Caprinae (Capra ibex and Ammotragus lervia) did exist in mid-Holocene Africa, they are highly unlikely to be found outside North Africa at this time and so all caprines are presumed to be domesticates with a west Asian origin (

Renfrew 1977). The subsistence patterns of the savanna pastoral Neolithic variant are different from the Elementaitan and Eburuan variants. I focus on the first three of these.

1.12 Savanna Pastoral Neolithic (SPN)

The SPN tradition spans 5000-1200 BP and is initially found near Lake Turkana at the beginning of the Holocene dry phase, ca. 5400-4000 BP (Figure 1.1). The SPN was originally called a “Stone Bowl Culture” by M. D. Leakey (1945) for the presence of bowls carved on soft volcanic tuffs and lavas. Evidence for domesticated animals first appears in Turkana ca. 4000 BP at FwJj 5 (Stone Bowl Site). The domesticated fauna is also found in association with aquatic fauna and terrestrial wild fauna. In addition two types of ceramic traditions represented at my site, Nderit and Ileret pottery, Ileret pottery is regarded as the younger part of the savannah pastoral traditions. Whereas

Nderit ceramic tradition is considered to be associated with first pastoral people to occupy northern Kenya (Nelson 1993), and is also found further south in the central Rift

Valley.

There is a substantial chronological gap between Latter Stone Ager and Savanna

Pastoral Neolithic. The earliest SPN sites appear further south, in the Central Rift Valley

2400 BP( Ambrose 1998). Ambrose (1998) documents SPN ceramics in association with

Eburran Phase 5 lithics at Enkapune Ya Muto, and thus proposes a long period of forager-food producer contact in this region before the southward spread of food production. As Nderit ceramics appear farther south, they are rarely found in mortuary contexts (Gifford-Gonzalez 1998). Bower (1991) suggests that the sparse occurrences of

Nderit and Ileret ceramics in the Central Rift Valley and in northern Tanzania (including at Mumba, Nasera and Seronera) represent an early “slow and gradual” spread of

31 pastoralism. With the advent of the modern climatic regime ca. 3000 BP, SPN is found across a wide region including northeast Uganda, central and southwest Kenya, and across the Serengeti/Mara plains to Lake Eyasi. Key sites include Gogo Falls, Prolonged

Drift, Lemek \and Narosura in Kenya; Nasera, Seronera, and Gol Kopjes in the Serengeti; and Mumbai, Jangwani and Gileodabeshta in Eyasi (Bower 1991). This represents

Bower’s (1991) “evolved pastoralism” phase, in which SPN traditions such as Narosura become widespread; he argues that there is stylistic discontinuity between earlier SPN traditions and “evolved” phase ceramics such as Narosura and Elementeitan.

Numerous ceramic traditions are grouped under the SPN banner (Barthelme

1985; Bower et al. 1977; Wandiba 1980). Ambrose (2001) lumps these into two across traditions: one includes Nderit and Ileret traditions, and the second includes Narosura,

Akira and Maringishu traditions. Bower (1991) suggests that Akira (documented at

Nasera) is later than Narosura (documented at Nasera, Mumba and other Eyasi sites), representing the final stage of the spread of the Pastoral Neolithic. Systematic study of

SPN tools is still lacking, and Ambrose (2001) suggests the SPN may lump several distinct lithic traditions. The assemblages include obsidian that may come from the Naivasha and Nakuru-Elmenteita basins in the Central Rift Valley. The diversity of both the ceramic and lithic assemblages called “SPN” makes this term a dubious cultural entity.

SPN economies are often dominated by domestic cattle and caprines, but at

Prolonged Drift, wild species comprise over 75% of the MNI (Gifford et al. 1980), and at

Mumba, Nasera and Seronera the faunal assemblages are dominated by wild taxa

(Prendergast 2008). As noted above, there is a substantial gap between the earliest

32 domesticates in northern Kenya (ca. 4500 BP) and the southward spread of pastoralism ca. 3000-2500 BP. Domestic animals arrived even later in southern Africa (possibly coming via West Africa), with sheep remains near the Okavango Delta dating to ca. 2000 cal BP (Robbins et al. 2005) and at the Cape dating to ca. 2000-1600 cal BP (Sealy and

Yates 1994). The delay in the southward spread of herding is partly explained by the late arrival of favorable conditions coinciding with the advent of two annual wet seasons, as discussed earlier. But it also may be attributable to dangers to livestock as one moves south, including aridity, new predators and tsetse flies (Gifford-Gonzalez 1998, 2000).

Eburran Phase 5 (ca. 5000-1200 BP) is found in the Central Rift Valley at sites such as Enkapune Ya Muto, Hyrax Hill, Gamble’s Cave, Lion Hill Cave, Keringet Cave,

Eburu Station Lava Tube Cave, Masai Gorge Rockshelter, and Ol Tepesi Rockshelter.

Eburran Phase 5 is marked by the co-occurrence of Eburran lithics and ceramics that include Nderet, Ileret and Salasun traditions, as early as 4860 BP at Enkapune Ya Muto.

These ceramics are associated with pastoralists elsewhere, but concrete evidence does not appear at Enkapune Ya Muto until ca. 3990 uncal bp (4522-4310 cal BP), when domestic caprines first appear in the assemblage, and pastoralism does not become well-established until 3280 uncal bp (3716-3270 cal BP) (Ambrose 1998; Marean 1992).

Given this chronological gap, together with continuity in lithics between Eburran preceramic and ceramic phases, Ambrose (1998) suggests that Phase 5 represents the gradual adoption of pastoralism by indigenous hunter-gatherers. Many Eburran Phase 5 occupations are overlain by Elmenteitan levels.

The Elmenteitan tradition (3000-1200 BP) is found in highlands of southwestern

Kenya, the Loita-Mara plains, and the western side of the Central Rift Valley. Important sites include Ngamuriak, Prolonged Drift, Gogo Falls, Wadh Lang’o, Njoro River Cave, and Enkapune Ya Muto. The sites’ restricted geographic distribution, compared with the distribution of earlier sites in drier environments, suggests that the occupants were selecting locations with good grazing opportunities. Ambrose (1984a, 1984b) suggests that by ca. 2500 BP, Elmenteitan herders expanded southward into areas already occupied by users of SPN ceramics. Bower (1991) considers the Elmenteitan, along with

Narosuran, to be part of the “evolved Pastoral Neolithic” discussed above. At Gogo Falls and Wadh Lang’o, Elmenteitan levels directly overlie Kansyore levels. Elmenteitan ceramics, formerly called “Remnant Ware,” are mostly undecorated, except for occasional bands of rim decoration, and they often have lug handles. Stone bowls carved from volcanic tuffs are also common, as are pestles and grindstones. Elmenteitan lithic toolkits rely on long blades, heavily retouched and reused, many of which are of obsidian from remote sources (Merrick et al. 1994; Nelson 1980; Robertshaw 1988). As noted above, Robertshaw (1991) and Seitsonen (2004) document dramatic change in raw materials between the Kansyore and Elmenteitan at Gogo Falls and Wadh Lang’o.

From a linguistic point of view, Ehret (1984, 2002) argues that Elmenteitan people had a

Sudanic (Southern Nilotic) origin, representing a second wave of nonindigenous food producers after the arrival of SPN herders, which might explain the marked discontinuities in material culture. Elmenteitan faunal assemblages are dominated by domesticates (cattle and caprines) in the Loita-Mara region and the Central Rift Valley

(Ambrose 1984b; Marshall 1986, 1990a, 1990b), but have a more diverse mix of wild and domestic terrestrial fauna, fish and shellfish at Gogo Falls and Wadh Lang’o, which may have been a specific regional adaptation (Marshall and Stewart 1995; Prendergast

2008).

As can be seen in the following chapters, in neither case are there clear-cut results, and as happens so often in anthropological archaeology, the prehistoric reality was probably much more complex than the material signatures left behind.

Nevertheless, the obsidian sourcing and characterization data corroborated with archaeological data presented here provide guidance for the interpretations that follow.

Figure 1.1: : East African fishing, foragers and herder sites. Pastoral Neolithic assemblages in Northern Tanzania, Central Rift valley and the Lake Turkana Basin

CHAPTER TWO

Geological, Environmental and Archaeological Background

2.1 Introduction

Initial studies on the Holocene archeology in Lake Turkana Basin were initiated by Robbins (1967, 1972, 1984, and 2006) in the western side of the lake, and latter by

Barthelme (1985), Gifford-Gonzalez (1977), Stewart (1989) and Kiura (2005, 2008) on the eastern side of the lake Turkana. This study represents the second generation of research that characterizes the Holocene in Lake Turkana Basin. The site descriptions are represented by excavated context which large scale excavations reported here of were five new archaeological assemblages (FwJj 5, FwJj 25, FwJj 25W, FwJj 27 and GaJi

4). These sites occur in the Galana Boi Formation based and on technological analysis of recovered assemblages, and are attributed to the Pastoral Neolithic (PN) tradition. The

Galana Boi Formation has been securely dated at between 10,000 years to the present

(Butzer 1980; Owen et al. 1982; Owen and Renaut 1983). Although the Galana Boi outcrops are exposed over hundreds of square kilometers on the margins of Lake

Turkana, previously excavated sites from the Koobi Fora area are restricted to a few paleontological collecting areas (Barthelme 1981, 1985). This research therefore represents a first attempt at large scale excavations and raw material sourcing in the

Galana Boi Formation east of Lake Turkana. In this chapter, a detail the geological

37 environmental and archaeology of these site to pastoral economy my in Turkana Basin.

Discuss the climatic changes under which herding economy was introduced in Turkana basin.

2.2 Location

The East African Rift Valley is described as a system of graben basins which runs from as far north as the Red Sea and far south as Malawi (Frostick 1997). The rift is marked by a series of lakes, including Lake Turkana and volcanoes, such as Mount

Kilimanjaro and graben shoulders highland plateaus along the rift (Frostick 1997; Olago et al. 2009). Each basin is controlled by faults and forms a subsiding graben or trough, near one hundred kilometers long, a few tens kilometers wide, and filled with sediments and/or volcanic rocks. These successions of graben basins are generally bordered on the two sides by high relief, comprising almost continuous parallel highlands and plateaus, and sometimes volcanic massifs. Rift hydrology is influenced by seasonal precipitation and surface run-off (Gasse & Street, 1978; Yuretich, 1982), local water table controls and tectonically controlled morphological barriers and volcanic dams which intercept axial and lateral drainage and contribute to the formation of many closed hydrological basins ( Garcin et al. 2009; Olago et al. 2009).

Lake Turkana as mentioned above is one of these graben lakes that are located in the East African Rift System. Lake Turkana is located in Northern Kenya at about 3N,

360 E (Figure 2.1). Lake Turkana is one of the oldest and largest (7,500km sq and 125 m

38 maximum depth) closed-basin water masses found in the semi-arid East African Rift

System (Owen et al.. 1982; Yuretich 1979) and the second largest hydrologically closed in Africa. Lake Turkana is approximately 250 km long with the widest section of the lake measuring 40Km, and the narrowest point is about 20 Km. A narrow and shallow bathymetric sill exists, adjacent to the Turkwel and Kerio Deltas at the southern end of the basin, thus dividing the lake into two sub-basins (Figure 2.2). The average water depth of Lake Turkana is 35 m, while the maximum depth is 125 m (Owen et al. 1982;

Yuretich 1979)

Lake Turkana waters are moderately saline and alkaline (pH 9.2), and are derived mainly (80%) from Ethiopian highlands through the Omo River (Butzer 1971; Yuretich and Cerling 1983). In the north, salinity is seasonally reduced through mixing with the

Omo River floodwaters, I n contrast at high salinity at the southern end of the lake. All the rivers draining into the western part of the lake, with the exception of the quasi- perennial Turkwel and Kerio Rivers, are dry for most of the year, flowing for only a few days or even hours after rain (Walsh and Dodson 1969). The Turkwel River carries water into the lake for several months in a normal year and forms an extensive delta in the

Central Sub-basin (Olago and Odada 2000). The internal drainage system to the southern end of Lake Turkana is due largely to the rainfall run-off west of Nyiro

Mountain and around the lake shore. Most rivers flowing into Lake Turkana have been forced to cut courses through a series of lava flows or pyroclastic deposits (Olago et al.

2009). In the southwest corner of the lake, however, the shoreline opens out to form a gently curving arc with sand and gravel beaches. The eastern side of the lake is generally

39 flat-lying, with ephemeral streams draining into the lake, but their contribution to the total water and sediment input is very small. Figure 2.1 shows that further north the ephemeral rivers such as the Ileret River and the Tula-Bor River, draining from the

Surgei-Asille plateaus along the basin margins enter the lake on the eastern site

(Frostick and Reid 1990).

The entire water column in the lake is well mixed throughout the year by strong, diurnal winds (Ferguson and Harbott, 1982). The principal ions are Na+, HCO,- and Cl-, with relatively low concentrations of Ca2+, Mg2+ and SO2 (Halfman et al. 1989). The lake receives run-off and sediment from a wide geographical area (Figure 2.1). Other streams, direct rainfall, and groundwater flow are considered insignificant in the water budget (Yuretich and Cerling 1983). The total water input is approximately balanced by evaporation, the current lake level is ca 365 m A.S.L. Water circulation in the lake is not well known, but preliminary investigations by Yuretich (1979) and Ferguson and Harbott

(1982) indicate a seasonal variation in the surface circulation. This current system is apparently controlled largely by the strong southeasterly winds and the seasonal flooding of the Omo River. Very little thermal or chemical stratification has been detected in the lake; apparently the shallow depth, together with the intense wind mixing, produces an essentially homogenous water mass (Figure 2.2).

Types of vegetation include intermittent woody riverine forests and semi-desert scrub, mainly acacias. Others include herbaceous vegetation and semi-desert grassland with annual and perennial scrub (Barthelme 1985; Butzer 1982). Sibiloi National Park was established in 1973 by the government of Kenya for the protection of wildlife and

40 paleontological sites; the park covers 1570 km². It was listed as a UNESCO World

Heritage Site in 1997 as a part of Lake Turkana National Park.

Figure 2.1: Location of Lake Turkana in Northern Kenya

Figure 2.2: Bathymetric map of Lake Turkana (Adopted from Hoffman 1987)

2.3 Geological Sedimentary Setting and Stratigraphy

To the north of the lake, the base rock geology consists of Tertiary to Pleistocene basalts, trachytes, phonolites and rhyolites of the Ethiopian Highlands with outcrops of granitic gneiss basement in the lower regions to the south this area is covered largely by alluvium deposited by the Omo River (Figure 2.3). Precambrian rocks (mainly quartzite and amphibolite schists) are present in only 7% of the Omo River drainage area, which accounts for 58% of the total catchment area of the Lake Turkana Basin (Ferguson and

Harbott 1982). The eastern edge of the research area is bordered by the volcanic highlands of the Surgei-Assile plateau. On the western side of the lake,the sediments currently being subjected to erosion are a mixture of fluvial, fluvial-lacustrine and littoral lacustrine ranging in age from the Pliocene to the Holocene (Figure. 2.3). In the southwestern hinterland of the lake, there are extensive outcrops of Precambrian basement rocks, consisting of biotite gneisses, hornblende gneisses, and migmatites and plagioclase amphibolites of the Upper Proterozoic Turbo-Kitale Group (Pallister 1971).

The sediments adjacent to the Kerio- Turkwel Rivers drainage system contain quartz, feldspar, illite and smectite, derived from the Precambrian gneisses and schists which characterize the area (Halfman et al. 1989). Closer to the lake shore on the western side, the alluvium cover is extensive, deposited by the Turkwel and Kerio Rivers as they wind their way to the lake.

The sediments infilling the Turkana basin date to >6 Million years old. The Plio-

Pleistocene deposits are well studied and have provided important insights into the history of human biological, behavioral and cultural evolution (Braun 2006; Brown and

Feibel 1986; Feibel 1988; Harris 1978; Leakey et al. 2001; Rogers 1997; Walker and

Leakey 1988). The sediments decrease in age upwards with a hiatus at 40,000-10,000 years before the onset of the Holocene. The Galana Boi Formation occurs around the lake margins and rises up to 80m above the present lake level of 365m A S L (Butzer et al. 1972; Owen et al. 1982; Owen and Renaut 1983, 1986; Olago et al. 2009). The Galana

Boi Formation deposits are exposed intermittently over an area of 2000 square kilometers with sediment thickness ranging from ~1m to 10-30 meters. The Galana Boi

Formation deposits preserve one of the most complete Holocene archaeological records in East Africa (Barthelme 1985; Owen et al. 1982). At Koobi Fora the Galana Boi outcrops have a distinct gray sequence of lacustrine and shoreline sediment deposit that includes poorly consolidated diatomaceous sediments, siltstones, sand, and mollusks and fish remains (Owen and Renaut 1986). Through presently dry and seemly barren this landscape was once fertile grasslands that perhaps supported large pastoral populations.

The northeastern margin of the lake supports a diverse population of flora and fauna that is adapted to the dry semi-arid environment. The area receives two periods of monsoon driven precipitation rain, the long rains in March- through April and the short rains from October- December (Olago et al. 2009). In recent time, the area has witnessed sporadic rainfall patterns culminating in devastating droughts that killed large numbers of wildlife and livestock (per. Ob). The zones along the shores of the lake are dominated by spike grass (Sporobolus spicatus). When the lake level rises, these zones are the first to be submerged. The mainland is sparcely covered with semi-arid

45 comiphora/acacia vegetation with shifting sand dunes (Owen and Renaut 1986). Valleys and flood plains of the ephemeral rivers have relatively dense vegetation cover. The main channels such as the Ileret River (Figure 2.3) are lined with large throne acacia often 30m tall. This riverine forest gallery rapidly grades into shrubs and steppe or grasslands. Most of this vegetation is used in a variety of ways by the Dassanetch population living in the area. For example, the Dassanetch grow sorghum and millet during the seasonal flooding of this river. This area also supports an array of dry land adapted fauna, some of which are constantly in competition for pasture with the caprines and cattle owned by the local people. Although most of the wild angulate population has been poached, the lake shore environment is rich with abundant predictable resources such as crocodiles, fish, turtles, hippos and a large variety of birds.

Figure 2.3: Outcrop of Tertiary and Quaternary strata at the study area

2.4 History of Holocene research in Turkana Basin

Lake Turkana itself is a geologically recent phenomenon, but what is now the

Lake Turkana basin has an archaeological record that stretches back 2.4 million years.

The paleontological record extends back to the Cretaceous Period (Brown and Feibel

1986).

Systematic archaeological studies of the Holocene deposits at LTB were initiated in the 1970s. First, a reconnaissance survey by Larry Robbins in the late 1960’s led to the discovery of Lothagam, an important fishing settlement located to the southwestern side of the lake. Lothagam was important in three ways. First, it is the first major Later

Stone Age fishing settlement discovered in Kenya. Second, it focused attention on Lake

Turkana in several major theoretical contexts in African archaeology such as the introduction of domestic stock. Third, and most importantly, it resulted in the discovery of decorated wavy line pottery buried in early Holocene sediments. This discovery created a challenge to the prevailing view about emergence of pottery in the pre-food production era in sub-Saharan Africa (Robbins 1967, 1972, 1980). Archaeological assemblages from Lothagam included bone harpoons and microlithics, fish remains, undecorated pottery and human skeletal remains (Robbins 2006, 1972). Subsequently,

David Philipson then of the British Institute in Eastern Africa (BIEA) initiated excavations at Lowasera, a fishing settlement site situated near the southern eastern end of the lake

(Philipson 1977b). Lowasera yielded abundant bone harpoons, fish, and lithic microlithics. Pioneering work carried out by Barthelme (1981, 1985, and 1985) on the eastern side of Lake Turkana at Koobi Fora added to the growing body of information

48 regarding the early and middle Holocene adaptations to the ancient beaches in Lake

Turkana Basin. This wave of research demonstrated that early Holocene human occupation (Lothagam and Lopoy) that had previously been discovered by Robbins at the western side of the lake were not unique or isolated Holocene occurrences but part of a larger early to late Holocene human adaptation in East Africa. At Koobi Fora, John

Barthelme (1985) investigated a four-kilometer long section of Holocene lake sediments on the eastern side of the lake. He found thirty (30) sites (including both fishing and pastoral Neolithic sites) and sampled fourteen of them, including seven Later Stone Age fishing settlements associated with the seventy-five-to eighty-meter lake stage (above the 1976 lake level). Significantly, twenty-nine radiocarbon dates were obtained for these sites, including the Pastoral Neolithic sites that will be discussed in Chapter 5.

Large numbers of bone harpoons were found in the fishing settlements. Barthelme’s

(1985) work confirmed the association of the wavy line pottery with the early Holocene deposits. From his research Barthelme was able to demonstrate that three distinct subsistence groups (hunter-gatherers, fishers and pastoralists) lived in the area during the Holocene. Barthelme argued that the earliest sites found near the basin margins and within the eastern volcanic highlands may have been Later Stone Age hunter-gatherer camps (Figure 2.3). Barthelme notes that these localities date to around 9300BP, lacked pottery and faunal remains yet have a distinct stone tool industry composed mainly of fine grained microlithics. Since there is little or no direct evidence of food production at these sites it has been difficult to characterize the diet of these people.

Barthelme has reported that the most numerous archaeological sites are the early to middle Holocene fishing camps. The earliest lake phase that Barthelme recognizes has been reconstructed from outcrops of early Holocene lacustrine silts and littoral sands in collection areas. Archaeological sites in these deposits date to 9300 BP and are correlated to a lake level rise of about 75-80 meters above the 1976 lake level.

The 80m level is the highest level before spill over in the Nile drainage system (Harvey and Grove 1982). Present day lake level is 365m above sea level. These sites have yielded evidence of diets consisting of mainly fish and other aquatic and wild terrestrial fauna. Sites found at this high level were interpreted by Barthelme as fishing camps and are all located along beach ridges and other high grounds. Material culture found at these lake levels includes bone harpoons, decorated and undecorated pottery, crescents, backed blades, unstandardized outils écaillés, and cores (Barthelme 1985).

Sites with barbed bone harpoons are a widespread Holocene phenomenon occurring throughout Northern Africa (Sudan), central and eastern Africa (Keding 2000; Yellen

1976).

A lower lake during the mid Holocene, brought lake levels to 55 m above the

1976 lake level. During this phase, the first appearance of domestic animals was documented at about 4000 years ago. Numerous sites interpreted as pastoral camps with high numbers of domesticated fauna in direct association with pottery and lithic artifacts occur at this former lake level and the subsequent levels within the Galana Boi

Formation (Figure 2.3). In addition there are large numbers of fish bones found in association with archaeological material. There are sites situated adjacent to lake shore

50 lines and along margins of paleo-rivers and springs (Ashley et al. in press). This suggests a reliance on fresh water resources by both humans and animals. Some of these resources included fish, turtle and crocodile. This line of evidence is supported by the presence of bone harpoons at these 4000 BP sites. Barthelme (1985) suggested that the inhabitants may have also used other techniques besides bone harpoons to acquire fish.

Barthelme’s pioneering research at Koobi Fora was followed in the mid 80’s by work carried out by the Koobi Fora Field School at the Jaragole pillar burial site (Nelson

1993). This locality is on an ancient beach that formed during the 55 meter high lake level at about 4000 years ago. The assemblage from Jaragole is comprises of broken ceramic vessels, animal figurines, beads and animal bones (Nelson 1993).

Later, detailed work carried out by Stewart (1989) on the fishing populations in

LTB showed that initially, people mainly subsisted on Nile Perch and Cichlids, and that subsequently when the lake level dropped species diversity increased. Stewart argues that the initial fishing adaptation during the early Holocene at Lake Turkana ‘‘represents small hunting groups exploiting fish resources on a seasonal basis’’ (Stewart 1989:352).

Diane Gifford-Gonzalez (1977) also undertook an ethnoarchaeological study using the

Dassanetch as modern analogues that could help shed light on pastoral mobility patterns in lacustrine environments.

From the mid 80’s to late 90’s there was a hiatus on Holocene research, as attention shifted towards Plio-Pleistocene research on early human evolution and paleoecology ( Braun 2006; Brown and Feibel 1986; Leakey et al. 2001; Rogers 1997). It was not until the onset of the new millennium that we begun to witness a new

51 generation of Holocene oriented research. Kiura (2006, 2008) used an ethnoarchaeological approach to reconstruct the diets of the Holocene population using stable carbon and nitrogen Isotopes. Kiura’s work demonstrated that different populations can be separated through stable isotope analysis based on isotope variations among modern humans living in present day landscapes, east of Lake Turkana with different dietary practices. Her research has direct application to understanding diet in the archaeological record.

Despite all the generalization about the assemblage composition, currently unresolved questions largely concern, the extent, timing and mechanisms of intensification from fishing to economic change to pastoralism. In particular there is need to understand the regional relationships in the inception of food production in

Lake Turkana Basin.

2.5 Paleoenvironmental reconstruction and climate change during the

Holocene in Turkana Basin

East African paleoenvironmental data for the late Quaternary and Holocene climatic changes have been captured from different archives and indicate that Africa in general and East Africa in particular has experienced significant episodes of climate change during the Holocene. The lacustrine rift basins of East Africa are potentially excellent recorders of past climate and therefore provide an unprecedented record of hydrological fluctuations in the Northern Kenya rift (Garcin et al. 2009). Data obtained from different geological proxies such as studies of diatoms, lake level changes, lake

52 chemistry, and lacustrine sediment cores (Butzer 1980; Harvey and Grove 1982; Owen et al. 1982; Umer et al. 2004) indicate that the early to mid Holocene was wetter than it is today. Different methods of dating including Accelerated Mass Spectrometry (AMS) radio carbon and Optical Stimulated Luminescence (OSL) have been able to provide a high resolution data on the chronology of environmental change in the Turkana Basin

(Ashley et al. In press). Detailed discussion on the above mentioned dating methods and how they were used for this study will be presented in Chapter four.

Studies on lake level changes, diatoms, and lake core sediments, have actively been undertaken during the last several decades. At the southwestern end of the lake, the Holocene beds were investigated and named the Kabua Beds (Robbins 1972, 2006;

Walsh and Dodson 1969). The southeastern section was investigated by Philipson (1977) at Lowasera and more recently by Wright (2007). Detailed investigations of the Galana

Boi Formation at the study area covered by this project were reported by Ashley et al.

(in press), Butzer (1980), Owen et al. (1982), Owen and Renaut (1983). According to these studies, there have been two-three episodes of high lake stands dated between

10-7000K BP, 6500-4500BP and 3250-1000BP (Ashley et al. in press; Barthelme 1981,

1985; Owen et al. 1982; Owen and Renaut 1983). Lake levels were universally high and over flowing until the return of drier conditions during the mid Holocene. Evidence of transient fluvial connectivity between Northern Kenya rift lake basins have been reported in Suguta Valley (Garcin et al. 2009) central rift valley (Ambrose2001;

Richardson 1972) and at Lake Turkana to the Nile drainage system -80m above the present 365m ASL (Butzer 1980; Harvey and Grove 1982; Olago and Odada 2000; Umer

53 et al. 2004). This “African Humid Phase” (1000-7500BP) witnessed the growth of fishing communities in North, Central, and East Africa, discussed below. The “African humid phase” was punctuated by brief wet events. For example, a diatom study from East

African lakes (Barker et al. 2001; Owen and Renaut 1983) attributes the same period of

O18 enrichment to heavy snowfall at high altitudes. The early to mid-Holocene was cooler and wetter than subsequent periods, with more expansive grasslands and reduced forest and woodlands (deMenocal et al. 2000; Hassan 1998).

A reduction in African fishing communities may have begun during the middle

Holocene dry phase ca. 6000-3000 BP, which was drier than the early Holocene, but still wetter and warmer than today. This period is punctuated by two drying events ca. 5200

BP and 4000 BP, during this time lake levels declined, grasslands expanded, and forests and woodlands shrank (Mworia 1991). These events coincided with major droughts documented in West Asia and North Africa (Thompson et al. 2002). In East Africa, this period coincides with the beginning of the Neolithic, discussed below. The Central Rift

Valley lakes dried completely ca. 3400-3000 BP (Ambrose 2001b), and to the north, the

Lake Turkana waters dropped drastically (Harvey and Grove 1982). The increasing aridity also had profound effect on indigenous food resources that may have forced population to seek alternative subsistence strategies (Marshall and Hildebrand 2002).

Domestic stock appears in northern Kenya at the beginning of the Neolithic but makes a slow and patchy entry into more southerly areas such as the Central Rift Valley and the Northern Tanzania (Ambrose 1998; Bower 1991). The southward expansion of pastoralists’ ca. 3000-2500 BP coincides with the advent of the modern climatic regime,

54 in which there is bimodal rainfall distribution resulting in two wet seasons, conditioned by the Intertropical Convergence Zone (ICTZ). These now occur around March-May and

October-December. This climatic change, Marshall (1986, 1990) argues, may have enabled the southward expansion of pastoralism by supporting grass growth through a larger part of the annual cycle. Although these studies have important implications for mobility, extent, and timing of pastoral lifestyles, more work is needed to determine the broader spatial distribution of artifact patterning and artifact traditions within and outside of the Lake Turkana Basin. The timing and manner in which domestic stock was introduced in east Turkana Africa, raises an important research question. On whether the arrival of domestic stock in Turkana Basin was due to demic population movements

“or down the line” technology transfer? A consequences a different hypothesis on the origin of domestication in Northern Kenya and thus the archaeological spread throughout Kenya, the central Rift Valley and Northern Tanzania have been proposed

(Ambrose 1998; Lane 2004).

Figure 2.4: Lake Turkana Lake level changes during the Holocene (adopted from Harvey and Grove 1982)

Figure 2.5: Location of Pastoral Neolithic sites and fisher settlements at Turkana Basin

2.6 Obsidian Quality and Availability in Turkana Basin

Obsidian is found in many volcanic regions of the world, and is abundant in East

Africa (Merrick and Brown 1984; Merrick et al. 1994; Ndiema et al. 2010; Negash and

Shackley 2007; Negash et al. 2006). In Africa, the most studied sites are in Ethiopia,

Eritrea, Great Rift Valley of Kenya, and in Northern Chad (Skinner 1983). The initial investigation of obsidian sourcing in Kenya was conducted by Mary Leakey when she demonstrated that obsidian samples from Hyrax Hill in central Rift Valley were similar in reflective index and geochemical characteristics to obsidian found at Njoro Cave (M. D.

Leakey 1945). In 1964, Cann and Renfrew (1967) briefly mentioned the trace element analysis of a handaxe from Kariandusi in the central Rift Valley. Further north at the

Laikipia Plateau, Walsh and Powys (1970) used refractive index and specific density to demonstrate that some of the obsidian artifacts from Kisima Farm in Laikipia were probably made of obsidian from the Naivasha Basin, some 130 km away. A number of other related studies on sourcing and characterization were from the central Rift Valley

(Bower et al. 1977; Michels et al. 1983; Omi and Agata 1977). It was not until the mid

80’s that Merrick and Brown (1984) initiated an obsidian sourcing and characterization project. This project was later expanded in scope to include obsidian from the Lake

Turkana Basin. More importantly Merrick and Brown’s ( 1984) research demonstrated that there were potential, but apparently relatively minor, sources of volcanic glass present in the northern portions of Kenya, east of Lake Turkana and in the southern end of the Suguta Valley.

The obsidian sources from Lake Turkana Basin range in age from as early as 5.6 mya (Tadiwos et al. 1998) to as recent as 25 kya (Giday et al. 1992), indicating the availability of these sources for utilization by populations from ancient times to the very recent past. Geological survey in the region suggests that sources of obsidian are few, relatively localized geographically and associated with Miocene through Pleistocene pyroclastic flows and deposits (Merrick and Brown 1984; Watkins 1981). These sources contain obsidian, for the most part, in the form of small pebble sized lapilli in many source areas including North Island, the Surgei-Asille plateau and Shin areas, the obsidian with the best flaking properties is found in seams along the chill zones at the bases or tops of lava flows (Figure 2.5).

Another geological locality at Northern Kenya, the North Island in Lake Turkana for example, the obsidian is commonly found as lapilli or nodules embedded in pyroclastic deposits which can vary from soft ash to well cemented tuff (Per Obs.).

Nodules collected for this study varied from small pebble size to boulder size, up to a meter in diameter. At least some of the obsidian present at most of the sampled localities is of adequate quality for toolstone working. At North Island blocks of obsidian are still plentiful on the surface of the outcrops, and even today extensive quarrying would not be necessary to collect adequate supplies.

In addition there are samples of obsidian at Shin and Surgei along the Eastern margins of Koobi For a sedimentary basin. However, the obsidians sampled from Shin and Surgei localities are generally of poor quality and are unlikely to have been used as raw material for making stone tools. However, obvious traces of flaking debris at

59 outcrops, associated with quarrying and related prehistoric activities are rare at the sites in Lake Turkana Basin (Merrick et al. 1994; Merrick and Brown 1984; Ndiema et al.

2010). The lack of evidence for obvious quarrying is expected as the area is undergoing intense erosion. Evidence of quarrying at Surgei could also have been obscured by the loose sediments on the surface and active livestock tracks that would have covered any evidence of quarrying. It should however be noted that at a number of the sampled localities, including Surgei and Shin, the obsidian bearing tuffaceous agglomerates contain quite low densities of obsidian lapilli and quarrying would have been relatively unproductive.

The sources at Surgei plateau on the other hand, were so small that at distances of 20 meters away from the outcrop secondary cobbles are rare. At distances of 1 km or more obsidian is completely absent from modern day drainages. This suggests that if these samples were used by prehistoric peoples, they were procured directly from the outcrop and not obtained from secondary, erosion deposits. Sample selections show that these sources are extremely friable and have numerous impurities suggesting they may have been unattractive to toolmakers concerned with producing standardized tool forms.

This chapter has highlighted in great detail the geology, sedimentology, and paleoenvironmental background of the research area. I have also discussed the history of Holocene specific research that that has continued to take place in this area. A general survey on the inception of food production in the greater rift valley has also

60 been presented. The next chapter I will discuss the various methods that were used to achieve the outlined research objectives.

Figure 2.6: Location of obsidian sources that were sampled for this study

CHAPTER THREE

Site Descriptions

3.1 Introduction

The multi-tier project described in this dissertation followed a logical progression of: 1) fieldwork, 2) laboratory analysis and 3) interpretation. In this chapter, I present the initial site description, an account of the survey, procedures and methods of excavation, of five Pastoral Neolithic sites under investigation (GaJi 4, FwJj 5, FwJj 25 and 25W, and FwJj 27). The site descriptions include the chronological and stratigraphic contexts, recovered assemblages and the paleogeographical contexts. A components of this project involved raw material sourcing survey and excavation as the field goal. The laboratory component entailed analysis of lithic artifacts, and geochemical characterization of archaeological and lithic source samples. Because the siteassemblages contained the largest sample to date of obsidian artifacts systematically excavated from Pastoral Neolithic sites from the Galana Boi Formation (GBF) beds it was imperative to provide the geographical locations, detailed site descriptions and the excavation procedures.

3.2 Procedures and methods of excavation

Excavation procedures reported here represent the initial description of artifact assemblages from the following sites; FwJj 5, FwJj 25, and 25W, FwJj 27, and GaJi 4. All the sites under investigation are located within the Holocene deposits geologically defined as the Galana Boi Formation along the northeastern shores of Lake Turkana.

Although the Galana Boi Formation outcrops are spread over hundreds of square kilometers along the eastern shores of the Lake Turkana Basin, previously excavated sites are located in specific sections of the Basin. Barthelme’s (1981, 1985), Philipson’s

(1977a) and (Robbins 1967) excavations at Koobi Fora, Lothagam and Lowasera respectively demonstrated the presence of three different subsistence groups namely; fishing settlements, foragers, and pastoralists (Figure 3.1).

The new excavations conducted for this dissertation in the Galana Boi Formation were initiated for the following reasons: first, the existing assemblages from FwJj 5 and

GaJi 4 that Barthelme excavated did not yield sufficient data on pastoralist’s subsistence and mobility patterns, especially those from the FwJj 5. In order to compare a range of behaviors at mid Holocene sites from obsidian artifact assemblages from this time period to assemblages in other parts of the basin and different time periods, it was necessary to expand the site sample size. Second, apart from site GaJi 4, archaeological materials from the initial excavations by Barthelme had not been securely dated

(Barthelme 1985). Given the nature of variability in behavioral signatures exhibited among Holocene foragers (Ambrose 2001b; Dale 2007; Lane et al. 2007; Mutundu 1998;

Prendergast 2008), it was important that new samples were obtained and multiple techniques used that would yield secure dates. Due to a lack of secure chronological

64 control it was probable that the initial round of research conducted by Barthelme and others in the Galana Boi Formation did not document the full range of prehistoric variability, mobility, and settlement patterns among these ancient foragers and herders.

Figure 3.1: Fisher settlement Pastoral sites at worked at By Philipson, Barthelme and this study

Lowasera

3.3 Excavations

Surveyed and excavate five archeological sites (4 in Area 10 at Ileret and 1 in Area

102 at Koobi Fora) (Figure 3.1) in the northeastern margin of Lake Turkana Basin (LTB) was conducted over the last 3 years was conducted under the close supervision of my main academic advisor Prof. J. W. K. Harris, and co investigators Drs P. Kiura (National

Museums of Kenya), C. Dillian (Coastal Carolina University), B. Keding (University of

Colon, Germany) and Prof Gail Ashley (Rutgers University). First, I started with a systematic surface sampling and small-scale test excavations around the perimeters of site locations in order to define site size and boundaries before beginning larger-scale archaeological excavations. Excavation trenches were selectively placed over areas of dense surface finds. The excavation trench was aligned according to terrain slope so as to maximize the thickness of the target deposit intervals. A total of 100 m2 were excavated from four sites, FwJj 5 (20 m2), FwJj 25 (16 m2), FwJj 25W (46 m2), FwJj 27 (12 m2), and GaJi 4 (26 m2).

Excavations at FwJj 5 and GaJi 4 started with the relocation of the original datum and reconstruction of the coordinate system used in 1970’s (Barthelme, 1981, 1985) in order to maintain consistency with earlier research. Site report data from the original excavations were used in determining the final position of levels at these sites.

Excavations at sites that were previously excavated by Barthelme, (FwJj 5 and GaJi 4) were undertaken using the same excavation techniques outlined above, but since the sites had previously been excavated, there was a need to come up with a systematic

67 methodological approach to reestablish the previously excavated squares. First,

Barthelme’s field notes from previous excavations were an important source to reestablish the location of earlier squares and excavation levels. At FwJj 5, Barthelme’s datum was realigned with the new excavation grid and therefore this enabled establishing to use the same excavation levels that Barthelme had used in his study. The excavation grid was set at a scale of 1000 Northing: 1000 Easting: 100 Elevation (X: Y: Z) using a Topcon DT 209 digital laser theodolite that was actively synchronized with a handheld TDS Ranger windows CE device. Because the mapping strategy used the landscape as the unit of reference and analysis, a single datum was established and three sites Area 10 (FwJj 25, 25W and 5) were all mapped into a single excavation grid.

This was because of the close proximity of these three sites. Each trench was excavated by hand using an assortment of tools ranging from trowels, dental picks and custom fashioned wooden digging implements popularly known as “Olduvai picks”. The excavation was conducted by a small team of highly skilled and very experienced excavators from the Archaeology Section at the National Museum of Kenya (NMK). A group of students from the Koobi Fora Field School (under the supervision of professional excavators) also assisted in with the excavation.

Excavation procedures were as follows: all stone artifacts, bones, and potshards

(regardless of size, and other artifacts,) were mapped into three dimensional coordinates using the instrumentation mentioned above. Individual specimens were collected and bagged with a data card containing the following provenience information:

a) Site name

b) Date specimens were collected

c) Unique catalogue number

d) Coordinates information: Northing (X) Easting (Y) and elevation (z)

e) Preliminary description

A duplicate digital copy of the same information was added to our on-site database. As required by Kenya law, these specimens were transported to the NMK lab in Nairobi.

The excavation was generally conducted in 10 cm spits. Where sediments were sterile, the arbitrary spit rule was maintained until another archaeological level layer, or a change in geological level was encountered. In these instances excavation spits were adjusted depending on artifact concentration or time available.

Individual finds were mapped in situ, and excavated sediments were screened for additional artifacts. At all excavation sites, sediments were dry sieved through 4mm sieves. Specimens that were recovered while excavating but in questionable spatial position, or were found in screens while sieving within a one meter excavation square were placed into designated level bags. The level bags were later individually sorted at camp by a group of trained archaeologists and myself. This lengthy process proved to be highly productive since some key finds including microlithics, ochre, modified ostrich eggshell, and beads not easily seen at the excavation site were documented.

Additionally, sorting through level bags at camp resulted in additional finds, exponentially increasing the number of specimens and other small animal bone specimens. Other preliminary analyses conducted in the field included a basic inventory;

69 including sorting and counting of artifacts based on general artifact type according to a above defined protocol. The second and more detailed analytical protocols were carried out at the National Museums of Kenya Archaeology Lab. This involved curation and systematic documentation of specific variables, mainly typological, technological and morphological.

In the new field strategies Barthelme’s previous profiles were used as guides in all the sites, so that excavation grids were placed to take advantage of intact deposits.

After the excavation was completed, section profiles were drawn and described with the assistance of project geologist (Prof. Gail Ashley) and Optical Stimulated

Luminescence (OSL) samples collected for dating.

Presented below is sites descriptions detailing, an inventory of recovered finds, local geology, dating and the associated Paleoenvironmental context.

3.4 GaJi 4 (Dongodien)

GaJi 4 is a large locality situated in the Galana Boi deposits in Area 102 along the

Koobi Fora Ridge. GaJi 4 is one of the sites that were previously excavated by Barthelme as part of the pioneering Holocene research at Koobi Fora. In order to test the accuracy of Optical Stimulated Luminescence (OSL) dating these sediments and to increase the sample size of obsidian artifacts there was need to excavate more sites. In addition these factors, and the relatively unexplored OSL dating technique and obsidian provenience studies at Lake Turkana Basin, prompted to consider re-excavation at GaJi

4. In Dec 2008 and January 2009 a 20 square meter trench was opened along the outcrops, using Barthelme’s field notes and partially-visible trenches edges as guides

(Figure 3.4). The large quantity of specimens recovered is credit to the skilled excavation team from the National Museums of Kenya. The trenches were placed to take advantage of the sloping aspect of the deposits so that we could have a “direct bite’ into the deposits in line with the stratigraphic sequence of the outcrops (Plate 3.1). The main site datum (1000N, 1000E, 100Z) was oriented to the East of the excavation area and approximately aligned to the grid of the previous excavations (see Figure 3.4). The main excavation unit was 5.5 meters above the main site datum. For logistical reasons another datum point was established closer to the excavation trench. This new datum was located at 960.81N; 932.27E; 106.97Z at a foresight angle of HR 2390 56” 35’ (HR 59

0 56” 35’backsight) from the main site datum. After excavation and profile studies, the project geologist assisted in describing and analyzing the stratigraphic context of the excavation trenches.

3.4.1 Dating

The two samples, OSL-GB-17 and OSL-GB16 (from section marked A and B) GaJi 4 were dated using Optical Stimulated Luminescence (OSL). In addition, one of the horizons (section marked A) contained charcoal (samples were collected by John Kamau in 1988) that was dated by radiometric carbon (Figure 3.3). The principle behind OSL dating is that, grains of quartz when exposed to sunlight are “bleached” i.e. have no

71 crystal lattice distortions. When buried and thus hidden from exposure to light, they accumulate trapped charges due to ionizing radiation from radionucleotides in the sediment. Radiation distorts the crystal lattice and this energy accumulates steadily over time. The energy is released as luminescence after receiving light stimulation in the lab.

The age of the sediment (last exposure to daylight) is a measure of the paleodose

(radiation dose to which the crystalline material has been exposed) divided by the total radiation dose for each year (Aitkens 998; Murray and Olley 2002). OSL dates quoted are ages in thousands of years before AD 2009. For direct comparison with radiocarbon ages in ka BP, subtract 0.059 ka from the OSL ages.

Table 3.1 show the dates from both OSL and C14 for site GaJi 4. All the charcoal samples were obtained from level AD-GB-14-08 which was just above the artifact

Horizon B (AD-GB-15-08). Dongodien A layer = 3.68 =/- 0.23 ka BP (is younger than the radiocarbon dates of 4200 BP ka by a few hundred years). The use of the two techniques was to test the accuracy of either method to show that there was reasonable correspondence between these two techniques hence OSL could reliably used to date the other sites.

3.4.2 Local geology and stratigraphy

The Dongodien and the Holocene deposits in Area 102 have a complex stratigraphy (Owen and Renaut 1986; Owen et al. 1982). Previous excavations at the sites and the adjacent surrounding areas emphasized that the stratigraphy is dominated by a series of cut-and-fill structures dark brown silty clays, fine silts, silty sands, coarse beach sands and gravel (Figure 3.3). The stratigraphic sequence at GaJi 4 is described in

Table 3.2 and illustrated in Figure 3.3. 11 distinct stratigraphic units were recognized.

Sample AD-GB-16-08 was obtained from the bottom most strata. The boundaries between the two layers where sampled AD-GB-02-08 and AD-GB-03-08 were collected were rather clear and easy to differentiate during excavation. It therefore seems safe to conclude that the assemblage had good stratigraphic integrity. Layer from which sample

AD-GB-08-08 was similar to AD-GB-08/09-08 but layerAD-AG-10-08 deepens steadily being replaced by sandy silt fining downwards into massive silt. However at Strata AD-

GB-15-08, it becomes massive silt very compact and blocky with some carbonates. The archaeological excavation was undertaken in 10 cm spits until a sterile layer was reached. Table 3.3 presents the stratigraphic distribution of assemblages at the site. The only unusual feature that was discovered in this trench was an ash patch. The ashy patch measured 30 cm in diameter and was 10 cm thick. This section mainly consisted of layers of powdery grey ash with minute pieces of charcoal. The strata from which sample AD-GB-14-08 and AD-GB-02-08 were collected yielded archaeological material there layer where sample AD-GB-16-08 was collected was completely sterile.

3.4.3 Archaeological Assemblage

Excavations by this study, placed in layer AD-GB-02 and AD-GB-14-08 and surface sampling at GaJi 4 recovered a total of 1123 lithic specimens, 2755 bones, 798 pot shards and 24 other specimens. Of the lithic specimens, 76.4% exhibit modification either through use or trimming or backing. Overall, modified artifacts constitute 17.6%, and the material categorized as both angular fragments, hammer stones and grinding stones. Excavated fauna were poorly preserved. Only 15% of the bone fragments were large enough for identification. Table 3.4 show the general composition of the assemblage recovered from GaJi 4. Faunal assemblage that were recovered from the artifact Horizon A, comprised of a full suite of body parts including both axial and appendicular elements. Numerous teeth and mandibular sections were recovered in the excavation. The faunal collection includes ovicaprines (goat and sheep). With regard to density of artifacts, the general trend was a low density at the base and then gradually increased until level AD-GB-02-08 where it was the highest concentration (circa 30 specimens per meter square) that is reported in table 3.4. The significance of this stratum was the presence of charcoal at level AD-GB-11-08. Although stratum B yielded abundant material, an important feature used to differentiate this stratum from other strata, was the presence of pottery, lithic artifacts, etc. The analysis here is focused in stratum AD-GB-02-08 where cultural material constituted the bulk of the finds. Due to

74 time and financial constrain samples for were not collected for floatation and phytoliths analysis.

The artifacts were distributed in low density patches coarsening upward the 5 meter section. There was no evidence of erosion within beds or between beds and thus the sediment records is intact and the spatial distribution of the archaeological material can therefore be assumed to directly reflect behavioral events at the site. All of the assemblage were packaged and transported to Nairobi where they are currently housed.

3.4.4 Paleoenvironmental Context

The site of GaJi 4 represents complex interaction between lake margin sedimentary processes and minor secondary pedogenic processes that produced the present stratigraphy. The site is situated in an interesting position both paleogeographically and chronologically. The middle- to late Holocene was an interesting time period in the Turkana Basin because this time period represents an important time period of increased aridity (Barthelme 1981; Harvey and Grove 1982).

The site seems to have formed on the margin of Lake Turkana when it stood at 55m higher than today. The two occupation horizons seems to have been a result of small scale fluctuation of the lake .The coarsening up of the sediments as seen nature of the wall section suggests that the shoreline where humans deposited artifacts and bones were quickly buried . It does not appear that the artifacts or bones were exposed on the surface for long because they do not appear to have been affected by sub-aerial

75 weathering processes. It is also likely that lake regression started before the deposition of the artifacts.

Site Sample No Material Method Date unCal Date Cal

GaJi 140-45#370 Charcoal AMS- 4180 +/- 40 BP 4770 to 4580)

4 Standard

GaJi 2 15-20 Charcoal AMS- 4250 +/- 40 BP 4840 to 4780

4 #585 Standard

GaJi 70-75 Charcoal AMS- 4150 +/- 40 BP Cal BP 4750 to

4 #1795 Standard 4710

GaJi 7 30-35 Charcoal AMS- 4220 +/- 40 BP Cal BP 4680 to

4 #2370 Standard 4640)

GaJi OSL GB- Sand OSL 2.65 +/- 0.18ka ------

4 16 BP

(Archeologi

cal level) (A)

GaJi OSL GB- Sand OSL 4.04 +/- 0.27ka ------

4 17 BP

(Archeologi

cal level B )

76 Table: 3.2: Stratigraphic description of geological sections at GaJi 4 (analyzed by A. Du)

Sample Grain Number Color Size Sorting Roundedness Mineral Composition 10YR 6/4 Light AD-GB- yellowish medium mainly quartz, some magnetite, very 01-08 brown fine sand poorly sorted angular little garnet medium sand w/ 10YR 5/4 coarse AD-GB- Yellowish sand mainly quartz, some magnetite, very 02-08 brown grains poorly sorted subangular little garnet AD-GB- 2.5Y 7/3 Pale medium mainly quartz, some magnetite, very 03-08 yellow sand poorly sorted angular little garnet coarse AD-GB- 2.5Y 7/3 Pale medium mainly quartz, some magnetite, very 04-08 yellow sand poorly sorted subangular/angular little garnet AD-GB- 2.5Y 7/3 Pale medium moderately 05-08 yellow fine sand sorted Sub-rounded mainly quartz with some magnetite AD-GB- 2.5Y 7/3 Pale mainly quartz, some magnetite, very 06-08 yellow fine sand poorly sorted angular little garnet fine AD-GB- 2.5Y 7/3 Pale medium moderately mainly quartz, some magnetite, very 07-08 yellow sand sorted subangular little garnet AD-GB- 2.5Y 6/2 Light very fine moderately mainly quartz, some magnetite, very 08-08 brownish gray sand sorted subangular little garnet coarse AD-GB- 2.5Y 8/3 Pale medium moderately mainly quartz, some magnetite, very 09-08 yellow sand sorted subangular little garnet AD-GB- 2.5Y 8/2 Pale coarse moderately-well mainly quartz, some magnetite, very 10-08 yellow sand sorted subangular little garnet AD-GB- 2.5Y 8/2 Pale medium moderately mainly, quartz, some magnetite, 11-08 yellow sand sorted subangular-angular very little garnet

AD- very fine GB- 2.5Y 6/3 Light sand w/ mainly quartz and yellow-stained quartz with some magnetite and 12-08 yellowish brown some silt poorly sorted angular garnet AD- GB- 2.5Y 6/2 Light very fine mainly quartz and yellow-stained quartz, some magnetite, very 13-08 brownish gray sand poorly sorted angular little garnet AD- GB- 2.5Y 6/2 Light mainly quartz and yellow-stained quartz with some magnetite and 14-08 brownish gray silt poorly sorted subangular garnet AD- GB- 2.5Y 5/3 Light olive mainly quartz and yellow-stained quartz with some magnetite, 15-08 brown silt poorly sorted subangular garnet, and mica AD- GB- 2.5Y 6/2 Light mainly quartz and yellow-stained quartz, some magnetite, very 16-08 brownish gray silt poorly sorted subangular little garnet 78

Table 3.3: Stratigraphic distribution of assemblages at GaJi 4

Elevation Bone/Teeth Lithics Fish Bones Pottery Others

105.20-105.00 2 4 1 0 1

104.99-104.90 13 3 1 9 2

104.89-104.80 19 9 0 16 4

104.79-104.70 35 11 2 13 22

104.69-104.60 39 11 0 19 4

104.59-104.50 15 5 0 8 1

104.49-104.40 8 2 0 6 1

104.39-104.30 2 0 0 3 0

104.29-104.20 0 0 0 0 0 79

Table 3.4 show the general composition of the assemblage recovered from GaJi

Total Archaeology Description % (N) Mirolithics 54 4.8 Scrappers 4 0.4 Outills Ecailes 32 2.8 Whole Flake 468 41.7 Broken Flakes 264 23.5 Angular Fragments 264 23.5 Lithic Hammer Stones 9 0.8 Grindstones 4 0.4 Cores 24 2.1 Stone Bowl 0 0 Total 1123 100

Nderit ware 128 16 Burnished/Slipped 216 27.1 Other Decorated 59 7.4 Disc 26 3.3 Undecorated 364 45.6 Pottery Internally Scored 2 0.3 Handles 3 0.4 Total 798 100

Bone Fragments Bone/Teeth 1462 53.1 (NID) Fish 1264 45.9 Turtle 1 0 Bird 12 0.4 Bones with art 1 0 Horn Core 2 0.1 80

Teeth Mammal 13 0.5 Total 2755 100 Teeth Bone Artifact 0 0 Charcoal 4 16.7 Ostrich Egg shell 2 8.3 Beads Angular Silty Blocks 0 0 Fire-cracked rocks 0 0 Other Hematite 3 12.5 Calcite crystal 0 0 Ostrich Egg shell 15 62.5 Fragments Total 24 100 Total Excavated 4700 100 81

Figure 3.2: Paleontological collection areas at Koobi For a showing the location of sites 82

Figure 3.3: The stratigraphic sequence of the outcrops at GaJi 4 (section logged by A. Du) dates in table 3.12a and b

B 83

Figure 3.4: site sampling and excavation at GaJi 4 (adapted from Barthelme 1985)

3.5. Area 10 deposits

New Holocene record was centered in Area 10 and several sites geographically in close proximity were investigated (see Figure 3.5).

Figure 3.5: Area 10 collections areas at research area

Area 10

3.6 FwJj 25W:

This site is located west of FwJj 5 and almost due southwest FwJj 25 in Area 10 of the Koobi Fora paleontological collection areas (Figure 3.2). The site is 442m ASL and thus lower than ~455m the position of highest lake level (Figure. 2.4). During one of our targeted survey one of the team members noticed a dense scatter of artifacts eroding from the ground that indicated that the location had good potential for excavation. A test trench was put in and yielded an overwhelming amount of material. The trench was subsequently extended and designated as Trench A. Surface scatters at FwJj 25W extend over an area of ~250 m2. A sample of the whole site (trench 15m by 12m) and two 2m by 3m trenches were tested. As noted earlier, the deposit at the site was partly washed away due to the rains and livestock trampling. But, our trench was located a safe distance from this area, and also removed from areas with dense vegetation. These excavations specifically targeted areas with dense concentrations of artifacts. It is therefore likely that these units accurately represent some of the cultural activities that took place across the immediate surroundings. Ideally a larger sample of the environs landscape should be excavated in the future to confirm these claims.

3.6.1 Date and Chronology

This site was dated using OSL technique. Having established the reliability of OSL by comparing dates obtained from OSL and C14 at GaJi 4, and time and resources being 87 at a premium it was decided that OSL technique was to be used to date this site (see

Table 3.1). One OSL sample OSL GB-03-05 in the archaeological horizon produced a date of 4.200 +/- 0.28 ka and the overlying sterile layer (OSL GB-12) was dated to 1.34 +/-

0.13 ka (Table 3.11a and b).

3.6.2 Local geology and stratigraphy

The stratigraphy of the site was compiled from two, 2-meter thick sections located 50 meters apart from each other, each end of the FwJj 25 “complex”; that is two distinct archaeological excavations connected by surface scatters. The deposits are composed of sediments fining upward, well stratified, pebbly-coarse sand to fine sand

(Figure 3.6). There was a sharp erosive lower contact with underlying Pleistocene grayish silt-clay sediment and a prominent undulating sharp contact within the section at the base of the archaeological layer. Gastropod and mollusk shells form lenses in the lowest beds, whereas individual shells and shell fragments were scattered throughout the upper beds. The sediment record from bottom to top is interpreted to represent a receding lake level producing a coarse beach deposit which is blanketed with eolian dune sediment. The archeological material at level 0.5-0.7 m below the main site datum is found immediately above beach sediments in the dune deposits. The OSL date of 4.14

+/- 0.53 ka (GB-12) came from the same horizon as the archaeology (Table 3.5). The archeological record is overlain with sterile silt dated at 1.39 +/- 0.19 ka that is interpreted as an interdune depression (Table 3.11a and b). The silt is capped with fine 88 sand dune sediment containing abraded scattered shells. As shown in Figure 3.8 only the boundaries between layers from the samples GB-O3-01-05 and GB-04-01-03 were noted as sharp otherwise the layers grade into each. Again archaeological material was recovered from section where sample GB 12-GB 13 was taken and diminished gradually up to the bottom gravely layer at 0.6m below the main datum. Some features such as cut and fill in the stratigraphical sequence of the site suggest that there was probably climatic fluctuations during the periods covered like those reported by Garcin et al. (

2009) from Suguta south of Lake Turkana. More analysis is required from different sites

/ locations in the basin to determine if the stratigraphical changes in the deposits only reflects changes in the local depositional and erosional environment or they really were systematic fluctuations of rainfall in the whole of Turkana Basin.

3.6.3 Archaeological Assemblage

The excavation at FwJj 25W during the two field seasons in July 2008 and 2009 recovered a total of 2971 lithic artifacts, 3266 ceramic shards, 1498 bone fragments and 93 others finds such as ostrich eggshell beads. Surface sampling during the same field season as above recovered a total of 134 lithic of artifacts, 106 ceramic remains, and 39 faunal remains. An inventory of both surface collected and excavated finds can be seen in Tables 3.5 and 3.6. Artifacts were not included in the analysis if weathering was so significant that it prevented geochemical or technological analysis. The assemblage was mostly concentrated between 10 and 20cm below main site datum 89

(100.09-100.20). The site had dense concentration of artifacts with distribution, being

20-100 finds per meter square within the levels mentioned above. The combined assemblage from the excavation and surface collections at FwJj 25W is among the largest Holocene assemblage within the greater Koobi Fora region. The excavation also recovered other finds including 10 charcoal fragments, 2 pieces of red ochre and 71 ostrich egg shell fragments and beads (see Table 3.5 and 3.6). All the above materials are currently stored at the National Museums of Kenya, Department of earth sciences,

Archaeology Section.

3.6.4 Paleoenvironmental Context

Site FwJj 25W is 442 m above sea level and thus slightly lower than ~455 m the position of highest lake level (Figure 2.7). The sediment record from bottom to top is interpreted to represent a rising, then fluctuating and falling lake level producing a coarse beach deposit which is overlain with eolian dune sediment.

3.6.5 Other finds

Other finds that were recovered from FwJj 25W include ostrich eggshell beads at various stages of production with the diameter between 2-3mm. There was no correlation between the diameter and coloration. Other finds included red ochre. It should be noted that the appearance of ochre has been documented at most PN sites. 90

Table 3.5: Inventory of surface collected finds FwJj 25W

% of Archaeology Description Total N) % Assemblage Microlithics 14 10.4 Scrappers 2 1.5 Point 0 0 Outlls Ecailes 3 2.2 Whole flake 16 11.9 Lithic Broken Flakes 0 0 Angular Fragments 98 73.1 Hammer stone 1 0.7 Grinding stones 0 0 Cores 0 0 Total 134 100 48 Rim Decorated 10 9.4 Rim Undecorated 15 14.2 Body. Decorated 30 28.3 Body Undecorated 45 42.5 Pottery Red Slip 0 0 Internally Scored 5 4.7 Handles 1 0.9 Total 106 100 38

Bone Fragments (NID) 25 64.1 Mammal Fish 12 30.8 Bones with art 0 0 Bone/Teeth Teeth 2 5.1 Ostrich Egg shell 0 0 Total 39 100 14 Total Surface collection 279 100 100

Table 3.6: A breakdown of the excavated finds at FwJj 25W

% of total Archaeology Description Total (N) Percent (%) Assemblage Angular Fragments 2561 86.2 Lithic Broken Flakes 60 2.0 Cores 7 0.2

Outils Écaillés 14 0.5

Grinding stones 2 0.1

Hammer Stones 2 0.1

Microlithics 65 2.2 Scrappers 1 0.0 Point 5 0.2 Whole flake 254 8.5 Sub Total 2971 100.0 37.95 Disc 13 0.4 Rim Decorated 58 1.8 Pottery Rim Undecorated 72 2.2

Body. Decorated 571 17.5

Body Undecorated 2260 69.2 Red Slip rim 151 4.6 Red slip Body deco 57 1.7 Red Slip body undec. 76 2.3 Internally Scored 8 0.2

Sub Total 3266 100.0 41.72 Bone w/Art Sur 3 0.2 Bone/Teeth Bone Frag (NID) 313 20.9

Mammal 815 54.4

Fish 342 22.8 Turtle 1 0.1 Crocodile 8 0.5 Teeth Mammal 16 1.1 Sub Total 1498 100.0 19.14

Beads Ostrich egg Other shell 21 22.6 Fragments Ostrich egg shell 50 53.8 Unmodified stone 10 10.8

Bone Harpoon 0 0.0 Charcoal Fragments 10 10.8 Hematite fragment 2 2.2 Sub Total 93 100.0 1.19

Total Excavated 7828 100.00

Figure.3.6: Stratigraphic section for FwJj 25 complex (section loggedd and drawn by G. Ashley)

3.7 FwJj 25

This site is located at Area 10 of the Koobi Fora paleontological collection areas and 100 meters NE of FwJj 25W.This site was previously discovered in 1995 by Mulu Muia who was then a research scientist at the archeology section of the National Museums of Kenya. The site was conspicuous due to the presence of human remains that were eroding from the deposits. Later in 2005, this site was established and conducted systematic surface sampling and excavations in four 2m by 4m trenches designated as trenches I, II, III, and IV. No human remains were recovered during my excvattion. The main sites datum and coordinate grid that was used for excavating all the sites reported from Area 10 (except at FwJj 27) were setup at this site.

3.7.1 Dating

Samples for OSL dating for this site were collected and analyzed following the protocol described above. An OSL date of 4.14 +/‐ 0.53 ka (GB‐12) came from the same horizon as the archaeology (Table 3.12a &b). The archeological record is overlain with sterile silt dated at 1.39

+/‐ 0.19 ka that is interpreted as an interdune depression. The silt is capped with fine sand dune sediment containing abraded shells scattered throughout the geological strata.

3.7.2 Local geology and stratigraphy

Modern erosional processes have exposed sediments going back to the Pleistocene.

Prof. Gail Ashley who was the project geologist for this multidisciplinary research project compiled the local geology and stratigraphy of FwJj 25.The Galana Boi deposits were distributed discontinuously over the landscape and were usually perched a top older deposits. A 5 meter geological trench (Figure 3.6) was excavated at a right angle along the horizontal axis of the

Holocene deposits. The basal Holocene units consisted of alternating lenses of fine diatomaceous silts and silty clay. This was then followed by a very coarse body of sand shells that contained shells of the fresh water oyster, large broken fragments of land snails this sand was interrupted by several instances of sands and gravel. The sediments are composed of fining upward, well stratified, pebbly‐coarse sand to fine sand. There is sharp erosive lower contact with underlying Pleistocene grayish silt‐clay sediment and a prominent undulating sharp contact within the section at the base of the archaeological layer. Gastropod and mollusk shells form lenses in the lowest beds, whereas individual shells and shell fragments are scattered throughout the upper beds.

3.7.3 Archaeological Assemblage

Excavation at FwJj 25 during the two field seasons in July 2006 recovered a total of 403 lithic artifacts, 116 pieces of pottery, 163 faunal remains and 42 others finds. Surface sampling at this site during the same field season as above recovered a total of 251 lithic of artifacts, 54 ceramic remains, and 61 faunal remains. A breakdown of surface collected and 95 excavated finds is presented in Table 3.7 and 3.8. Excavations at FwJj 25 were divided into four distinct trenches (Trench I, II, III and IV). 62.5% of the formal tools were made from ignimbrite,

Quartz and basalt raw material. Obsidian and other cryptocrystalline raw material accounted for 37.5% of the total raw materials. Faunal fragments that were recovered were poorly preserved and may seem to have been affected by post deposition taphonomic processes. The density of material at Fwjj 25 is low (less than 10 artifacts per square meter) thus it is possible to separate different patches of material. The presence of extremely small debitage suggests at least minimal post‐depositional water transport of the artifact assemblages. All materials are currently stored in the archaeology section of the National Museums of Kenya.

3.7.4 Paleoenvironmental Context

The sediment record from bottom to top is interpreted to represent a rising, then fluctuating and falling lake level producing a coarse beach deposit which is blanketed with eolian dune sediment. The archeological materials at FwJj 25 are found immediately above beach sediments in the dune deposits. 96

Table 3.7: A breakdown of the surface collected finds at FwJj 25

Percent Archaeology Description Total (N) (%) Microlithics 21 8.4 Lithic Scrapers 7 2.8 Point 1 0.4 Outils Écaillés 10 4.0

Whole flake 119 47.4

Broken Flakes 45 17.9

Angular Fragments 30 12.0 Hammer stone 2 0.8 Grounding Stone 0 0.0 Cores 16 6.4 Sub‐Total 251 68.6 Rim Decorated 13 24.1 Rim Undecorated 8 14.8 Body. Decorated 17 31.5 Body Undecorated 14 25.9 Red Slip 1 1.9 Internally Scored 0 0.0 Handles 1 1.9 Pottery Sub‐Total 54 14.8

Bone/Teeth Bone Frag (NID) Mammal 29 47.5 Fish 26 42.6 Bones with art 0 0.0 Teeth 4 6.6 Ostrich Egg shell 2 3.3 Sub‐Total 61 16.7 Total Surface collection 366 100.0 97

Table 3.8: A breakdown of the excavated finds at FwJj 25

% of total Archaeology Description Total (N) % Assemblages Microlithics 23 5.7 Lithic Scrappers 15 3.7

Outils écaillés 14 3.5

Whole flake 125 31.0

Broken Flakes 75 18.6 Angular Fragments 124 30.8 Grinding stones 11 2.7 Cores 16 4.0 Sub Total 403 100.0 55.66

Rim Decorated 25 21.6 Pottery Rim Undecorated 16 13.8 Body. Decorated 38 32.8

Body Undecorated 36 31.0

Red Slip rim 1 0.9

Red slip Body deco 0 0.0 Red Slip body undec 0 0.0 Internally Scored 0 0.0 Disc 0 0.0 Sub Total 116 100.0 16.02

Bone Fragments (NID) Bone/Teeth Mammal 93 57.1

Fish 36 22.1

Turtle 0 0.0 Crocodile 17 10.4 Bone w/Art Sur 0 0.0 Teeth Mammal 17 10.4 Sub Total 163 100.0 22.51

Beads Ostrich egg Other shell 6 14.3 Fragments Ostrich egg shell 33 78.6 Unmodified stone 0 0.0

Bone Harpoon 2 4.8 Charcoal fragments 0 0.0 Hematite fragment 1 2.4 Sub Total 42 100.0 5.80

Total Excavated Material 724 100.00

3.8 FwJj 5

The site of FwJj 5 is located in the Galana Boi Formation in Area 10 of the Koobi Fora

Paleontological collection areas (see Figure 3.2). FwJj 5 was discovered during the pioneering research o the Holocene deposits by archaeologist John Barthelme in the late 1970’s. The site was then named the “Stone Bowl Site”‐ (after the stone bowl fragments that were surface collected near the site). Basing on dates obtained from bone appétit and the presence of surface collected stone bowls, Barthelme argued that this was a Pastoral Neolithic site dating to the mid Holocene (Barthelme 1985). For detailed information on Barthelme’s excavation and related stratigraphic distribution at FwJj 5, refer to Barthelme (1981, 1985).

In 2007, new excavations were established, where I recovered at areas where highest density of artifacts were observed eroding from the surface. Two trenches A and B were laid down over a large lateral extent to determine the extent of the archaeological horizon and the vertical dispersion of artifacts within this horizon. Trenches A and B were located directly next to Barthelme’s excavations and recovered the majority of the artifacts (Figure 3.8).

Even though excavations for this study were much larger in extend (24 square meters) compared to Barthelme’s (circa 12 square meters), the number of artifacts recovered from

Barthelme excavation were however more than those recovered by this project.

3.8.1 Dating

The chronological disposition of the site was based on OSL dates carried out at Kansas

University. Sediment samples were taken from FwJj 5 in July 2007 using light proof containers 99 and following the protocol outlined above. Samples for OSL dating were collected from two points of the geological section Figure 3.7. An OSL date of 0.93 +/‐ 0.07 ka (GB‐14) came from the same horizon (Figure 3.9). The discrepancy between our dates and those presented by

Barthelme (1985; 1984) could be explained by several factors. First, it could be due to the complex stratigraphic relationship between deposits in Area 10 and therefore made a reconstruction really problematic. Second, it could be due to the problems inherent with bone appetite dating as this is the methods that Barthelme used (Koch et al. 1997; Surovell 2000).

3.8.2 Local geology and stratigraphy

The sites are 442m above sea level and thus stratigraphically lower than ~455m the position of highest lake level (Figure 3.10). Geological sections exposed adjacent to the archaeological excavations show that the artifact horizon is approximately 1.4 meters below the local datum (99.80). The stratigraphic section was based on two similar geological excavations that were placed 5 meters apart. Samples from the geological trench associated with the excavation were analyzed by project geologist Prof Gail Ashley of the Department of

Earth and Planetary Sciences, Rutgers University (Ashley et al. in press). Her analysis show that the 2.5 m thick deposit is composed of inter‐bedded and highly variable sands and silts (Figure

3.9). The bottom contact with Pleistocene sediments is sharp and erosive. Thin beds and lenses of gastropod shells occur in the lowest meter. Two weakly developed paleosols are intercalated with coarser beds. Carbonate nodules and localized carbonate cement occur throughout. Large chunks of tufa (carbonate‐cemented sand) ranging from 6‐12 cm in diameter 100 were found in the sandy archaeological layer at the top (Figure 3.9). The lake and lake margin sediments are capped with fluvial sediments that contain carbonate mineralogical evidence

(tufa) of freshwater springs or groundwater seeps. The position of the large tufa clasts within the sand bed indicates that the tufa was eroded from a site upstream in the drainage and transported during high discharge events. Terrestrial gastropods shells collected for stable isotope analyzes came from the paleosol (from sample GB‐06‐02‐05). The stable isotope data

(δ180 +1.0 to +2.0 and δ18C ‐2.0 to ‐2.2) have a distinctive signature compared to lacustrine

gastropods and the tufa (Figure 3.9). The archaeological assemblages were excavated from fluvial deposits (between 1.9‐2.5 m). Prof Ashley interpreted this to mean artifacts accumulated on the fluvial surface and were not likely fluvially transported.

The site of FwJj 5 therefore represents complex interaction between sedimentary processes and secondary geological events that resulted to the present stratigraphy. The site seems to have formed near to groundwater‐fed river system. The spring does not appear to have been active for very long. Despite the presence of a few small clasts, at the base of the section there are no obvious cross beds suggesting a significant fluvial system. It is possible that these features may have been moved by secondary diagenetic processes. The nature of the wall section suggests that the river banks where people deposited artifacts and bones quickly changed course and then finer sediments buried the artifacts and bones.

3.8.3 Archaeological Assemblage 101

Extensive survey was conducted at the adjacent vicinity of site FwJj 5 to prove that finds were not transported by the river system that is found in this area. I also wanted to ensure that finds were confined to the section where the original concentrations of artifacts were recovered. Although it was unlikely to relocate the original datum from Barthelme’s previous excavation it was possible to establish a grid that was compatible with Barthelme’s excavations.

Surface sampling recovered a total of 201 lithic of artifacts, 280 ceramic shards and 74 bone fragments. The following were recovered from excavations; 302 lithic artifacts, 220 pot shards,

155 faunal fragments and 55 other finds. An inventory of both the surface collected and excavated finds can be seen in Table 3.9 and 3.10. The surface assemblage composition from

FwJj 5 attests to the presence of wild and domestic, aquatic and terrestrial fauna implying a diversified subsistence base. Excavations were separated into two distinct trenches (Trench A and B).

102

3.8.4 Paleoenvironmental Context

The Galana Boi Formation section at FwJj 5 is 2.5 m thick. Deposit composed of interbeded and highly variable sands and silts (Figure 3.9). Thin beds and lenses of gastropod shells occur in the lowest meter, with scattered, broken shells near the top. The record is inferred to represent the beginning of a receding shoreline that eroded the Pleistocene deposits deposited superficial lacustrine mafic‐rich sands, coarse beach sediments with shells and finer‐grained backshore silty sands (Ashley et al. in press). The lake level fluctuated and subaerial exposure allowed an overprint of weakly developed paleosols to form on the lake margin sediments. Terrestrial gastropods shells collected for stable isotope analyzes came from the paleosol (GB‐06‐02‐05) (Figure. 3.7). The lake and lake margin sediments are capped with fluvial sediments that contain carbonate mineralogical evidence (tufa) of freshwater springs or groundwater seeps. The archaeological material was excavated from between 1.9‐2.5 m. in the fluvial deposits.

103

Table 3.9: Assemblage composition from surface collection at FwJj 5

Archaeology Description Total (N) % Mirolithics 3 1.5 Scrappers 4 2 Point 1 0.5 Outilis Ecailes 5 2.5 Whole flake 113 56.2 Broken Flakes 25 12.4 Lithic Angular Fragments 21 10.4 Hammer stone 11 5.5 Grinding vehicle 8 4 0 0 Cores 10 5 Total 201 100

Rim Decorated 11 3.9 Rim Undecorated 13 20 7.1 Body. Decorated 20 7.1 Pottery Body Undecorated 215 76.8 Red Slip 10 3.6 Internally Scored 1 0.4 Handles 3 1.1 Total 280 100

Bone Fragments (NID) 2 2.7 Mammal Fish 4 5.4

Bone/Teeth Bones with art 8 10.8 Teeth 53 71.6 Ostrich Egg shell 7 9.5 Total 74 100 Total Surface Collection 555 104

Table 3.10: Excavated assemblage at FwJj 5

% of sub % of total Archaeology Description Total (N) total Assemblage Microlithics 7 2.3 Lithic Scrappers 3 1.0

Outils Ecailes 9 3.0

Whole flake 74 24.5

Broken Flakes 56 18.5 Angular Fragments 123 40.7 Grinding stones 8 2.6 Cores 22 7.3 Sub Total 302 100.0 41.26

Rim Decorated 6 2.7 Pottery Rim Undecorated 8 3.6

Body. Decorated 60 27.3

Body Undecorated 141 64.1

Red Slip rim 1 0.5 Red slip Body deco 0 0.0 Red Slip body undecorated 2 0.9 Internally Scored 0 0.0 Disc 2 0.9 Sub Total 220 100.0 30.05

Bone Fragments Bone/Teeth (NID)

Mammal 62 40.0

Fish 45 29.0

Turtle 0 0.0 Crocodile 5 3.2 Bone w/Art Sur 0 0.0 Teeth Mammal 43 27.7 Sub Total 155 100.0 21.17

Beads Ostrich egg shell 2 3.6 Ostrich egg shell Other Fragments 21 38.2

Unmodified stone 23 41.8

Bone Harpoon 4 7.3 Charcoal fragments 4 7.3 Hematite fragment 1 1.8 Sub Total 55 100.0 7.51

Total Excavated Material 732 100.00 105

Figure 3.7: OSL samples taking at FwJj 5

106 Figure 3.8: Excavation at FwJj 5, modified from Barthelme (1985)

107 Figure.3.9: Stratigraphic section for FwJj 5 (section logged in and drawn by K.S. Bitting and G.M. Ashley)

108

3.9 FwJj 27

Site FwJj 27 is in Area 10 at the eastern shores of Lake Turkana, northern Kenya

(Figure 3.2). This is a newly discovered site where the mid Holocene transition is represented by in‐situ nearly complete human skeleton remains and interstratified artifact assemblage. After setting a corner datum stake, a total station was used to map the excavation area into square meter grids. The total station was also used to integrate geologic sections and to log several topographic profiles across the deposits catchment.

Given the absence of any obvious bedding planes in the paleodune sediment or grave

pit boundaries around the burials, excavation proceeded by dividing the area into a surface layer and burial levels of set depth. The human skeleton was excavated according to the general site protocol (outlined above) until the integrity of the specimen was at risk. It was then removed and placed in a plaster jacket and

transported by aircraft to Nairobi where it is stored at the National Museums of Kenya.

Laboratory preparations of this specimen are on‐going and detailed analysis will be reported elsewhere (Kiura et al. in prep).

3.9.1 Dating

The sediments for OSL dating (sample OSL‐GB‐10) were obtained from) layer GA‐

GB‐06‐05) being the same horizon as the archaeology and the human skeleton material

(Figure 3.11). These sediments were dated at 4.30 +/‐ 0.27 BP. The above layer was on top of much older early Holocene deposits that have now been dated to 9.03 +/‐ 1.04 BP 109

3.9.2 Local geology and stratigraphy

The stratigraphy of FwJj 27 was compiled from a geological trench located 5 meters from the location of the skeleton remains Plate 3.1. The sediments are composed of, well stratified, pebbly‐coarse sand to fine sand. There is sharp erosive lower contact with underlying early Holocene grayish silt‐clay sediment and a prominent

undulating sharp contact within the section at the base of the archaeological layer.

Gastropod and mollusk shells form lenses in the lowest beds, whereas individual shells and shell fragments are scattered throughout the upper beds. FwJj 27site is 442m above sea level and thus lower than ~455m the position of highest lake level.

The silt is capped with fine sand dune sediment containing abraded shells scattered throughout. As shown in Figure 3.11 only the boundaries between layer GB‐12 and GB‐13 are sharp otherwise the layers grade into each. The boundary between the

horizons was clearly visible in the stratigraphy and always very sharp as distinct giving an impression that there is likely a hiatus of deposition in between.

3.9.3 Archaeological Assemblage

The surface sampled archaeological material from FwJj 27 is relatively small; comprising of 52 lithic artifacts 25 faunal remains mainly unidentifiable fish bones and 8 ceramic remains. Out of the six pot shards that were recovered, only one was decorated. Information on raw materials and typological composition of the stone 110 artifact assemblage is presented in Table 3.11. The importance of FwJj 27 lies on the presence of mid Holocene skeleton remains.

3.9.4 Paleoenvironmental Context

Site FwJj 27 is 442m above sea level and thus lower than ~455m the position of highest lake level. The sediment record from bottom to top is interpreted to represent a rising, then fluctuating and falling lake level producing a coarse beach deposit which is

blanketed with eolian dune sediment. The archeological material at level 98.80‐98‐60 m

is found immediately above beach sediments in the dune deposits. Whereas it is possible that there might have been deposition of material at the site it seems likely the sites may represent different deposition events.

111

Table 3.11 Chronology table for FwJj 27

Archaeology Description Total (N) % Mirolithics 3 5.8 Scrappers 4 7.7 Point 0 0 Outils écaillés 0 0 Whole flake 24 46.2 Lithic Broken Flakes 10 19.2 Angular Fragments 10 19.2 Hammer stone 0 0 Grinding stone 0 0 Cores 1 1.9 Total 52 100

Rim Decorated 1 12.5 Rim Undecorated 0 0 Body. Decorated 2 25 Pottery Body Undecorated 3 37.5 Red Slip 1 12.5 Internally Scored 0 0 Handles 1 12.5 Total 8 100

Bone Fragments (NID) 18 72 Mammal Bone/Teeth Fish 7 28 Bones with art 0 0 Teeth 0 0 Ostrich Egg shell 0 0 Total 25 Total collection 85 100

112

Table 3.12 a and b: The Optical Simulated Luminescence dates for sites under investigation1

Site Sample Details Longitude Latitude Altitude Age in ka Error OSL Sample Code (°N) (°E) (m) before 2009 (ka) FwJj 27 GB‐10 4.29 36.31 442 4.30 +/‐0.27 FwJj 27 GB‐11 4.29 36.31 442 9.03 +/‐1.40 FwJj 5 (Stone Bowl) GB‐14 4.29 36.30 442 0.90 +/‐0.06 GaJi 4 GB‐17 3.94 36.30 442 4.04 +‐/0.27 (Archaeological Horizon B) GaJi 4 GB‐12 4.08 36.29 442 1.34 +/‐0.3 GaJi 4(Archaeological GB‐16 3.94 36.30 442 2.65 +/‐0.18 Horizon A) FwJj 25 GB‐03‐1‐05 4.08 36.29 442 4.20 +/‐0.28

Site OSL Sample Quartz HF U U‐ Th Th‐ K K- Rb Rb- H2O Code grain etch (pp Error (%) Erro (pp Error (%) Erro (mGya- size (μm) (min) m) (%) rm) m) (%) a-1) 1) FwJj 27 GB‐10 175‐212 60 0.90 1.98 0.10 42 6 1.18 5 2.5 0.14 6 FwJj 27 GB‐11 212‐250 60 1.10 1.55 0.08 49 7 9.08 5 2.1 0.11 2 FwJj 5 (Stone Bowl) GB‐14 175‐212 60 1.20 1.70 0.09 41 6 0.52 5 2.3 0.13 7 GaJi 4 (Archaeological GB‐17 175‐212 60 0.90 1.93 0.10 44 7 0.78 5 2.3 0.13 Horizon B) 9 GaJi 4 GB‐12 175‐212 60 1.00 2.01 0.10 40 6 1.00 5 2.6 0.14 0 FwJj (Archaeological GB‐16 175‐212 60 0.90 1.91 0.10 38 6 0.42 5 2.4 0.13 Horizon A) 0 FwJj 25 GB‐03‐1‐05 125‐175 60 0.60 1.74 0.09 37 6 0.56 5 2.1 0.12 8 (Dates were determined by J.Q.G. Spencer (Kansas University) errors are

113

Figure 3.10: Schematic cross‐section (a) of lake level changes during thhe Holocene at Turkana Basin and

location of study sites (created by G. Ashley)

(a)

(b)

114

Figure 3.11: Stratigraphic section form FwJj 27 (Section logged by G. Ashley) 115

Plate 3.1: Photos of geological trench a t GaJi 4

OSL-GB-17

116

Plate 3.2: Excavations at FwJj 25W.

117

Plate 3.3: The Human skeleton remains during excavation at FwJj 27

CHAPTER FOUR

Faunal Analysis

4.1 Introduction

This chapter describes the faunal assemblages recovered from the five

Holocene sites at Koobi Fora. This part of the thesis presents field and laboratory analysis building on pioneering studies of fauna recovered from the Holocene sites at

Koobi Fora by John Barthelme (1985). The fauna from this site was further analyzed by Fiona Marshall (Marshall et al. 1984) and Steward and Gifford-Gonzalez (1989).

The faunal assemblages reported here were basic descriptions and were studied at the National Museums of Kenya. This chapter is divided into (1) Laboratory and analytical procedures (2) Faunal descriptions by site and (3) a brief summary.

4.2 Laboratory and Archaeological Procedures

The following section describes the analytical protocol used and results of the

comprehensive analysis of the recovered faunal assemblages from my five sites under

investigation. All the faunal analysis reported here were performed at the archaeology

laboratory at the National Museums of Kenya (NMK). The faunal from these

archaeological sites comprises gross morphological description and contextual integrity.

The archaeological and contextual information were recorded and entered in a

database. 119

4.3 Faunal analysis

All terrestrial faunal remains with a maximum dimension greater than 2 cm,

along with highly diagnostic bones smaller than 2 cm, were examined and identified,

when possible. The majority of the faunal material was labeled with the site name and

catalogue number except those specimens that were too small. Cataloged bones were

used to provide the Number of Identified Specimens (NISP) values throughout my work.

Bones that could not be identified were bagged separately from the identified bones (by

excavation level) and were grouped using Gifford and Crader’s (1977) NID (non-

identifiable) model. All the faunal remains were prepared for analysis by washing using

clean tap water. The washing and analysis were undertaken by Mr. Paul Watene and

John Kimengich, both of whom are very experienced faunal analysts with an exceptional

eye for detail. This non-destructive technique was necessary to remove any matrix that could have obscured possible diagnostic features that would aid identification or any bone surface modifications such as burning, cut marks, and percussion marks. Washing bones was viewed as a better strategy than leaving the bones partly or completely encrusted. Without proper cleaning neither determination of NISP nor identification of surface modification would have been possible. Faunal analysis was not the central

focus of my dissertation and thus detailed data on bone surface modification and

mortality profiles were not recorded. Such analysis will be undertaken as part of the

larger multidisciplinary component of this project. Faunal remains from FwJj 25W and 120

Gaji 4 were well preserved and not encased in sediments hence no pretreatment was

necessary. Fragments belonging to a single bone with evidence of modern breaks were

refitted and reattached or bagged together. An attempted was made to refit ancient

breaks and those that refitted were not reattached, but were assigned the same

number and bagged together. Bones and teeth were identified to taxon and/or skeleton

element part whenever possible, but sometimes bones were only identified as axial or

appendicular portions. Additionally, some long bones could only be identified to upper

humerus or femur), intermediate (radi-ulna or tibia), or lower (metapodial). Minimum

Number of Individuals (MNI) was calculated where possible based on mammalian

skeletal elements.

Taxonomic identification to specific species level was generally not possible.

However, identification to subfamily, tribe, or genus was often possible using skeletal

elements that have distinct features, such as femoral head, glenoid fossa, teeth, or the

third phalanges of caprines. For detailed information on unique assessments of

taxonomic identification refer to (Bobe et al. 2007; Lyman 1994). The focus of my

dissertation was not on faunal analysis, and therefore, I did not undertake to

differentiate goats from sheep, types of cows, or age differences, apart from the

obvious ones such as age differences as indicated by erupting third molar or the degree

of and fusion of epiphysis to diaphysis (Plate 4.1). Efforts to differentiate goats from

sheep through DNA analysis were not successful (Horsburg 2007)

Unfortunately, the best one can do with most limb bone shafts and axial fragments is to assign them to size class. Since the vast majority of the mammalian taxa 121 in my collections are bovids, I often used bovid size classes. skeleton element were identified to, side and size following the Brain (1981) and Bunn (1981) classification of bones of African Mammals. Identification was made possible by comparison with the unique reference collection at the National Museum of Kenya, which includes not only representative specimens of every terrestrial taxon in the region, but also multiple specimens of the same taxon. This allowed for the consideration of variables such as individual size, sex and age when making comparisons.

Archaeological sites are the result of a series of pre- and post-depositional taphonomic processes that should be considered when undertaking taphonomic analysis (Lyman 1994). Data on bone weathering stages were collected where appropriate. Unfortunately this was only possible on fairly complete specimens where the surface preservation was acceptable using Behrensmeyer’s (1978) weathering index.

In Africa, flesh-consuming and bone-consuming carnivores present particular problems with regard to trace evidence in the archaeological record. These problems have been extensively addressed in the literature for Plio-Pleistocene sites, but are often less deliberated upon for later Holocene sites. A number of modern experiments have provided referential frameworks by which to interpret archaeofaunal data, specifically to determine the relative influence of carnivores versus humans in the creation of bone assemblages (Blumenschine 1986; Brain 1981; Capaldo and Blumenschine 1994;

Capaldo 1998; Marean and Cleghorn 2003; Marean et al. 1992, 2003; Pickering 2002).

Predators such as hyenas present the greatest threat to bone preservation, since unlike flesh-eating felids, they tend to break bones for their marrow, and chew or digest bones 122

with cancellous tissue to obtain grease (Pobiner 2008). The ability of bone-crunching

carnivores to delete a large part of the axial skeleton and the least dense limb epiphyses

is well documented in the above references. However, smaller carnivores such as

wild/domesticated dogs, jackals, and other fauna such as suids, baboons, and humans

are also potential bone-modifiers.

A number of other pre- and post-depositional factors, such as trampling ( Olsen

and Shipman 1988), sub-aerial or water weathering (Pante 2010), and bone diagenesis

resulting from burial conditions, can lead to bone damage that will often affect the least dense skeletal elements most dramatically. Finally, human food processing techniques such as roasting, pounding, and boiling bones for grease (pot sizing) (Marshall 1990) will dramatically affect cancellous bone preservation (Munro and Bar-Oz 2005). Bone

modification by humans is a significant factor that should be given careful consideration at Holocene sites, especially where there is evidence for fire and pottery, as is the case

at the sites under investigation. In summary, a number of processes tend to lead to an

over-representation of the densest parts of the skeleton (limb bone shafts, some cranial

parts (including teeth), and denser portions of epiphyses and phalanges) and an under-

representation of the axial skeleton and less dense epiphyses (Horwitz 2003).

To overcome these taphonomic biases and obtain better estimates of skeletal

part representation, all factors were considered when estimating the Minimum Number

of Elements (MNE), including those limb bone shafts that could be identified to element

(Marean et al. 2007; Pickering et al. 2004). Fragments identified to each limb bone were

laid out on a large surface (Plate 4.1). The MNE was then determined by jointly 123

considering obvious diagnostic features such as the foramina, crest of the tibia, size

differences (reflected in the thickness of the shaft at certain points), and age differences

(reflected in porosity, size, and heft of the fragment) were recorded. This approach

enabled me to calculate the most conservative MNE possible.

The methods described in this chapter have been applied to the sites described in the present study, with results presented below. These methods have enabled me to go beyond a simple list of taxa and to include taphonomic variables. Nevertheless, taxonomic representation remains one of the most intriguing features of sites with evidence of both domesticates and wild animals. By applying basic taphonomic criteria that have become standard for earlier periods of East African research, we obtain more information on site integrity, and ultimately on the economic activities associated with the Pastoral Neolithic (PN) that has been the subject of recent anthropological discussions.

4.4 Faunal Assemblage from GaJi 4

This site is located in Area 102 of the Koobi Fora collection areas (Figure 3.2).

Most of the excavated fauna from GaJi 4 had poor bone surface preservation and were highly fragmented. Only 25.1 % or 491 of the bone fragments (n=1953) were large enough to be identified (n=491). Figure 4.1 shows the proportions of wild (53%) to domestic (42%) fauna. The remaining 5% is made of small numbers of fish bone, birds and turtle that was highly fragmented and difficult to identify. Fish remains could have 124

been over-represented in the GaJi 4 faunal assemblage but because of the highly fragmented nature of the fish bone, they are not reported here. Table 4.1 and Figure 4.1 show the general faunal composition of the assemblage recovered from GaJi 4 based on

NISP. Maximally identifiable faunal were those that could be identified either to specific

taxon, bovid size or mammal size as opposed to those that could only be identified to

part of a skeleton element such as long bone fragment . Maximally identified analyses of

specimens were classified into three categories; first, the group that consists of

specimens that were identifiable to the exact taxon (accounting for 23.4 % of the

maximally identified specimens or 5.9% of NISP the total faunal assemblage). The

second group was assigned to the Bovid Size category (Brain 1981). Bovid size group two

(20-80kg) and three (100kg and above) accounted for 43.4% of total faunal assemblage and 10.9% of the maximally identifiable fauna based on NISP). The last group that was assigned to mammals sizes (Bunn 1981) which accounted for 21.8% of the total faunal assemblage and 5.5% of NISP of maximally identifiable faunal material that were recovered from GaJi 4. Medium to large mammals may have been more abundant than indicated by these figures, but were highly fragmented and difficult to identify. I believe that the taxonomic representation of small mammals in this assemblage is likely to be also underrepresented because small bones are less likely to survive taphonomic and post depositional processes. The assemblage at GaJi 4 comprised of 53% wild taxa compared to 42% domestic taxa, based on NISP (Figure 4.1). Detailed discussions on age estimations and mortality profiles from GaJi 4 have been reported elsewhere (Marshall et al. 1984). The surface assemblage composition from GaJi 4 attests to the presence of 125 both wild and domestic fauna, aquatic and terrestrial fauna implying a diversified subsistence base.

126

Table 4.1: Taxonomic representation/NISP distribution at GaJi 4

Skeleton (Dikdik) Very Caprines Small Bos. Medium Total Element Madoqua Small Bovid Sp. Bovid sp. Bovid (Ovicaprid (cattle Size) size) Horn core 0 0 0 0 0 0 0 Cranium 0 0 0 1 0 0 1 Maxilla 0 0 0 0 0 0 0 Mandible 0 0 0 2 0 0 2 Upper check 0 0 24 8 2 0 34 teeth Lower check 0 0 17 6 0 0 23 teeth Incisors 0 0 15 2 0 0 17 Vertebrate 0 3 1 23 0 0 27 Rib 0 3 0 33 0 5 41 Sternum 0 0 0 0 0 0 0 Scapula 0 0 2 8 0 2 12 Humerus 0 0 4 9 0 2 15 Radio-Ulna 1 1 11 12 0 1 26 Scaphoid 0 0 2 2 1 0 5 Lunate 0 0 1 0 0 0 1 Cuneiform 0 0 2 3 0 0 5 Magnum 0 0 3 0 0 0 3 Unciform 0 0 0 2 0 0 2 Pisiform 0 0 1 0 0 0 1 Metacarpal 0 0 1 10 0 0 11 Pelvis 0 0 1 18 0 0 19 Femur 1 0 2 9 0 1 13 Tibia 0 0 0 6 0 1 7 Calcanium 0 0 0 2 0 0 2 Astragalus 0 0 4 2 2 0 8 Mid shaft 0 0 2 1 0 0 3 fragment Medial 0 0 2 0 0 0 2 Cuneiform Lateral 0 0 0 4 0 0 4 Cuneiform Metatarsal 4 0 1 4 0 0 9 Metatarsal. 0 1 0 26 0 2 29 Indet Phalanges 2 0 11 20 4 0 37 Patella 0 0 0 0 0 0 0 Total 8 8 107 213 9 14 359 Assemblage % 2.2 2.2 29.8 59.3 2.5 3.9 100.0 127

Figure 4.1: Representation of wild and domestic composition based on NISP at GaJi 4.

Domestic Taxa 42% 53% Wild Taxa Others

128

Table 4.2: General Faunal Assemblage from GaJi 4

General Composition of Faunal Assemblage

Number of Percent specimens Maximally Specific Taxon 115 5.9

Identifiable (491) Bovid Size (1 & 2) 213 10.9 Mammal Size (2 & 3) 107 5.5 Long Bone Shaft Fragments 56 2.9

Non-Identifiable Fragments 1462 74.8 Total 1953 100.00

129 Figure 4.2: Taxonomic representation and NISP distribution at GaJi 4

130

4.5 Faunal composition at GaJi 4

This site is located at Area 10 of the Koobi Fora collection areas (Figures 3.2 and 3.3).

The faunal assemblage was recovered in the main excavation designated as Trench A.

There were no identifiable fauna in the original test excavation. This description focuses

on the in-situ faunal assemblage comprising a full suite of body parts including both axial and appendicular elements. Numerous teeth and mandibular sections were recovered in the excavation. Excavated fauna were well preserved as semi-fossilized

bone fragments by sub-aerial weathering processes. This means that the faunal

assemblages was not exposed on the surface for long and were buried quickly. Of the excavated faunal remains 9.7% of NISP were maximally identifiable. Table 4.3 presents the general composition of the faunal assemblage recovered from FwJj 25W.

Identification of analyzed specimens were classified into three categories; First, the group that consists of specimens that were identifiable to the exact taxon (accounting for 19.7% of the maximally identified specimens or 5.9% of NISP the total faunal assemblage). The second group was assigned to the Bovid Size category (Brain 1981).

Bovid size group two (20-80kg) and three (100kg and above) accounted for 3.6 % of the maximally identifiable fauna based on NISP). The last group that was assigned to mamma sizes (Bunn 1981) group two and three which accounted for 1.06% of NISP of maximally identifiable faunal material that were recovered from FwJj 25W. Medium to large mammals may have been more abundant than indicated by these figures but were highly fragmented and difficult to identify to species level. The difference in number of elements tends to increase with animal size. These patterns of fragmentation between 131

large and small animals could be the result of susceptibility to fragmentation due to

butchery and food processing techniques, post depositional leaching and profile

compaction. Long bone fragments and tooth fragments are the most represented

category in the whole faunal assemblage. This is expected because these parts are the

most numerous anatomical units in a carcass. Across the taxa, their representation in

relatively equal proportions which suggests minimal differences in survivorship among

taxa. The terrestrial fauna that were positively identified consists of, 53% of NISP wild

fauna, 32% of NISP domestic fauna, while aquatic fauna accounted for 15% of NISP (see

Figure 4.3). Taxonomic representation of GaJi 4, faunal assemblage is presented in Table

4.3.

Information on Minimum Number of Individuals (MNI) estimates for caprines and cattle are presented in Table 4.5. MNI estimates for cattle and caprine were drawn from a total of 68 dental specimens. including isolated M1 and M2. The MNI for caprines was estimated at 3 while that of cattle was estimated at 4 individuals. One interesting aspect is that based on the presence of 3 caprine erupting M3 it can be said there was a

significant number of juveniles represented in the assemblage (see Table 4.4).

132

Table 4.3: Inventory of Identifiable Skeleton Elements from FwJj 25W

Inventory of identifiable skeleton elements: Bovid Sizes

Body Part Size 1 Size 2 Size 3 Size 4 Indent Bone fragments: non- 6 524 identifiable Calcanium: left 1 Calcanium: right 2 Femur: shaft 3 4 Horn core 1 Humerus: proximal Humerus: shaft 1 4 Humerus: distal 1 Innominate 6 4 13 Long bone; Indent 331 Mandible: left 1 1 Mandible: right 1 1 Metapodial: distal 1 1 2 Metapodial: proximal 3 8 Metapodial: shaft 1 1 Phalanx 1 1 Radius: distal 1 Radius: shaft 2 9 Radius: proximal 2 Rib 1 1 4 32 Scapular 1 Sephroid 1 Skull 3 Tibia: Distal 2 Tibia: proximal 1 Tibia: shaft 2 3 2 6 Tooth :RM2 (upper) Tooth fragments 1 3 4 Tooth: RM2 (upper) 2 1 Tooth: RM3 (upper) 1 1 3 Tooth: RM3 (upper) 1 1 Tooth:LM1 (Lower) 1 2 Vertebrate: thorasic 1 Vertebrate fragment 1 7 Vertebrate: cervical 1 3 133

Vertebrate: lumbar 1 1 Total 10 36 11 16 959 Percent 0.9 3.5 1.06 1.5 92.9 134

Table 4.4: Inventory of mammalian identifiable skeleton element based on NISP from FwJj 25W

Inventory of identifiable skeleton element: Mammal Skeleton Element Caprine Small Bovid Cattle Large Bovid Indent Other Bone fragments: indent 0 3 0 2 82 Calcaneum: left 0 0 1 0 1 Calcaneum: right 0 2 1 0 Femur: shaft 0 3 0 0 2 Horn core 1 0 2 1 2 Humerus: proximal Humerus: shaft 1 4 Humerus: distal 1 Innominate 5 6 4 8 Long bone; Indent 821 Hemi-mandible: left 1 1 3 1 Hemi-mandible: right Metapodial: distal 1 1 1 Metapodial: proximal 1 3 1 Metapodial: shaft 2 1 Phalanx 1 2 7 Radius: distal 2 1 Radius: shaft 2 3 9 Radius: proximal 2 1 Rib 2 1 1 4 30 Scapular: glenoid 1 Spheroid 1 Skull 1 2 Tibia: Distal 2 Tibia: proximal 1 Tibia: shaft 0 1 2 2 5 1 Tooth: frag (indent) 7 2 4 28 3 Tooth:LM1(lower) 1 1 0 0 Tooth:RM2(lower) 1 Tooth:RM2 (lower) 2 Tooth:RM3 (lower) 2 2 1 Tooth:RM3 (upper) 1 1 Vertebrate: thorasic 1 Vertebrate frag: indent 1 14 Vertebrate: cervical 3 Vertebrate: lumbar 0 1 1 0 1 Total 21 32 32 19 1023 7 Percent (%) 1.8 2.8 2.8 1.6 91.0 0.6 135

Figure 4.3: Percent faunal representation for wild, domestic and aquatic fauna at FwJj 25W based on NISP

NISP of wild, domestic and aquatic fauna

15%

Aquatic

53% Domesticates 32% wild

136

4.6 Faunal composition at FwJj 25

A summary of faunal results from FwJj 25 are presented in Table 4.5. The faunal

assemblage comprises of poorly preserved elements that seem to have been affected by post deposition taphonomic processes. Large mammals may have been more abundant than indicated by these figures but were highly fragmented and difficult to identify. The difference in element tends to increase with animal size; these patterns of fragmentation between large and small animals could be a result of susceptibility to fragmentation due to butchery and food processing techniques.

137

Table 4.5: Inventory of identifiable skeleton elements from FwJj 25

Inventory of Identifiable skeleton elements from FwJj 5

Skeleton Element Caprine Small Cattle Medium Small Bovid Bovid Carnivore Mandible 0 0 0 0 0 Maxillae 0 0 1 0 0 Isolated Teeth 3 0 1 15 15 Femur 0 1 0 0 0 Metapodial 0 1 0 0 0 Calcaneum 0 1 0 0 0 Astragalus 0 1 0 0 0 Cuneiform 0 0 0 1 0 Phalange 0 1 0 0 0 Total Assemblage 3 5 2 16 1

Percent (%) 11.1 18.5 7.4 59.3 3.7

138

Table 4.6: Faunal composition at based on NISP FwJj 25

Total % of Total Mammalian 93 57.1 Crocodiles 17 10.4 Fish 36 22.1 Bovid Tooth 9 5.5 Human Teeth 8 4.9 Total 163 100.0

139

4.7 Faunal Composition at FwJj 5

Located at Area 10 of the Koobi Fora collection areas (Figure 3.2 and 3.3), this site was formally excavated by John Barthelme (1985) and referred to as the

“stone bowl” site. This name was based on number for stone fragments that we collected from the surface at this site. A summary of finds including faunal specimens from FwJj 5 is presented in Table 4.7. The faunal assemblage comprised of a sub-set of a full group of body parts including both axial and appendicular elements. A small number of specimens were recovered from the

excavation at FwJj 5 which is significantly different from the large assemblages

that were recovered from sites such as GaJi 4. The fauna from FwJj 5 could have been affected by post depositional taphonomic processes as all the specimens exhibited poor surface preservation. This was also in complete contrast to the fauna from Barthelme’s previous excavations (Barthelme 1985). Of the excavated faunal remains, 6.5% of NISP were identifiable. . The fauna that were positively identified include 3.2% wild fauna, 1.3% domestic fauna while aquatic fauna accounted for 39.7 % of NISP. The balance consisted of small non- identifiable fragments. 3.2% of faunal specimens were identifiable to the exact taxon. The second group was assigned to the Bovid Size category (Brain 1981).

Bovid size group two (20-80kg) and three (100kg and above) accounted for 1.8 % of the maximally identifiable fauna based on NISP). The last group that was assigned to mammals sizes (Bunn 1981) group two and three which was not represented. 140

Table 4.7: Identifiable skeleton elements from FwJj 5 based on NISP.

Identifiable skeleton elements from FwJj 5 based on NISP Body Part Caprine Small Cattle Medium Small Bovid Bovid Carnivore Mandible 0 0 0 0 0 Maxillae 0 0 1 0 0 Isolated Teeth 3 0 1 15 15 Femur 0 1 0 0 0 Metapodial 0 1 0 0 0 Calcaneum 0 1 0 0 0 Astragalus 0 1 0 0 0 Cuneiform 0 0 0 1 0 Phalange 0 1 0 0 0 Total Assemblage 3 5 2 16 1 Percent (%) 11.1 18.5 7.4 59.3 3.7

141

Table 4.8: Taxonomic representation of fauna at FwJj 5 based on NISP

Taxonomic representation of fauna at FwJj 5 based on NISP Small Bovid 5 0.6 Medium Bovid( cattle 1 0.1 Bovid size) Large Bovid 26 3.2 Caprines 3 0.4 Cattle 2 0.2 Size not Indent 15 1.8 Carnivores Small carnivores 1 0.1 Non Indent Non Indent 463 57.1 Reptiles Crocodile 1 0.1 Turtle 1 0.1 Fish Fish 319 39.5 Total Assemblage 811 100

142

Table 4.9: Inventory of Identifiable Skeleton Elements (NISP) from FwJj 5

Inventory of Identifiable Skeleton Elements from FwJj 5

Skeleton Caprine Small Cattle Medium Small Elements Bovid Bovid Carnivore Mandible 0 0 0 0 0 Maxillae 0 0 1 0 0 Isolated Teeth 3 0 1 15 15 Femur 0 1 0 0 0 Metapodial 0 1 0 0 0 Calcaneum 0 1 0 0 0 Astragalus 0 1 0 0 0 Cuneiform 0 0 0 1 0 Phalange 0 1 0 0 0 Total Assemblage 3 5 2 16 1 Percent (%) 11.1 18.5 7.4 59.3 3.7 143

Figure 4.4: Representation of domestic, wild and aquatic fauna at FwJj 5

Representation of domestic, wild and Aquatic fauna at FwJj 5

Wild Fauna Domestic fauna Aquatic Fauna NID (Mainly fish bone frags)

144

4.8 Faunal composition at FwJj 27

This site is located Area 10 collection areas (Figure 3.2). An excavation was undertaken at FwJj 27 (see chapter 3) to recover human skeleton. A small number of faunal specimens were recovered but were so small in size and fragmented for identification purposes. Unidentified fish bone remains accounted for approximately

50% of the fragmented faunal assemblage. As single born harpoon was surface collected hence no claims on the behavioral association are made here. The human skeleton will be described at the National Museum of Kenya scientists as part of the larger multidisciplinary project.

145

Plate 4.1: Faunal material recovered from FwJj 25W

(a)

(b)

146

4.9 Summary

This chapter has presented results from faunal assemblage recovered from the

sites under investigation. Apart from site FwJj 25 and GaJi 4 which had good but not

excellent preserved fauna the rest of the assemblage was poorly preserved. Whereas

the fragmentation would have been as a result of food processing techniques it could

also be due to taphonomic processes. Detailed discussion on the meaning of such

techniques will be presented in the discussion chapter (see chapter eight).

When it comes to faunal representation between the different sites it was found

that that there representation between GaJi 4 and FwJj 25W. There is almost equal

representation of wild and domestic terrestrial taxa are all represented in almost equal

representation. The percentage proportions of wild and domestic observed at the

studies sites, more so at GaJi 4 and FwJj 25W, shows similarities in terms of previous

archaeological research at Mugokodo rock shelter in the Laikipia plateau in central

Kenya (Mutundu 1998, 2010) and Mumba rock shelter in Northern Tanzania

(Prendergast 2008).The implications will be discussed in summary in Chapter Eight.

There are two possible explanations for this occurrence; one is that because of paleoenvironmental setting of this sites. Site GaJi 4 and FwJj 25 complex (FwJj 25 and

25W), are located in a dune paleo-lake setting and while FwJj was in a paleo-river bank

or spring deposits. The second possible explanation is due to the time difference. FwJj

25 and GaJi 4 are dated to mid Holocene while FwJj 5, is dated to the late Holocene when it have become very dry and there might have been overdependence on aquatic resources as we observed among pastoral communities living in Turkana basin. It could 147 also be that fish bones had better preservation at FwJj 5 than at FwJj 25. Detailed discussion on the behavioral implications of faunal compositions will be discussed in

Chapter Eight.

148

CHAPTER FIVE

Lithic Analysis

5.1 Introduction

Our ancestors manufactured stone tools to satisfy a perceived need. Acquiring the

raw material is the first step in the organization of technology as defined by Wilson

(2007). He argued that technological strategies are influenced by environmental

conditions, while socio economic strategies are implemented through the distribution of

design and activity that will ultimately be reflected in the artifact distribution. Identifying

the raw material sources, patterns of resource exploitation and land use can help

archaeologists to reconstruct prehistoric lifeways among ancient forager and herder

populations. Examining artifact types, size (maximum and minimum dimension,

technological length, breath, and width) is especially useful when formulating

archaeological correlates for relationships between technology and land use patterns. The basic decay model or linear function that states that artifact size diminishes as distance from raw material increases is a standard assessment of transport behavior

(Blumenschine et al. 2008; Braun et al. 2009)

The following are the analytical protocols used in the comprehensive analysis of

the recovered lithic artifacts from site GaJi 4, FwJj 5, FwJj 25, FwJj 25W and FwJj 27.

Lithic artifacts were analyzed using a hybrid system that utilized both the typological

and technological criteria established and used in previous research in the study of Late

Stone Age/Holocene stone artifact assemblages in Africa (for example; Ambrose 1984a;

1980; Siiriainen 1984; Robertshaw 1990). The techno-morphological analysis of Bordes 149

(1961), Braun (2006), Debenath and Dibble (1993), and were also used. I chose these

methods for three reasons. First, their methods are well known and understood in the

archaeological community. Second, the techno-morphological analysis of the Later

Stone Age in East Africa is not well developed especially at the aforementioned sites.

Third, both the technological record and practical experience of lithic analysts indicate that certain technological attributes are associated regardless of site, spatial and temporal relationships. The reasons for combining these methods were because the protocol was important in that it categorized the lithic artifacts and their raw material sources, gross morphological characteristics, technological characteristics, distribution across the landscape, and contextual integrity.

As part of the lithic analysis protocol reported here, all stone artifacts except

debris were classified using a unique four digit hierarchical number system by which

their attributes were coded using this numeric system. The coded system generated a

computerized relational database that could be used with statistical packages for both

multivariate and univariate analysis. The statistical analysis was performed at the Rutgers

computer labs using PAST software for windows.

The aims of the statistical analysis were; 1) to develop a clear description of

debitage, flakes, microlithics, and cores from the five sites under investigation; 2) to

measure and compare the technological change, style and function of tools from the five

sites; 3) to monitor and compare raw material variation from the sites under investigation;

4) to correlate my research with patterns of raw material procurement and use, with

obsidian as a possible indicator for variation in human mobility and land use patterns

among ancient herder and forager populations. 150

Technological variables such as retouch are important indicators of specific

behaviors and are therefore important when inferring transport decisions. Among the

variables that were compared from site to site included extent of raw material

exploitation and the degree of manufacturing investment. Artifacts were classified into

technological and typological groups based on degree of retouch. This was important

because it allowed broader assemblage comparisons. It also provided a basic

morphological characterization of the assemblages. The following were the variables that

were captured in my relational database:

a) Site name

b) Date specimen was collected

c) Unique catalogue number

d) Coordinates information-Northing (X) Easting (Y) and elevation (z)

e) Preliminary description

f) Raw material type

g) Morphological or technological attributes

h) Typological attributes

As noted above, the specimens that were recovered were each assigned a specific

catalogue number. These specific numbers were consistently used from site to site and

were progressively continued from excavations in one field season to the next. Specimens

that were surface collected were preceded with the prefix “SUR”- for Surface, where as those that were recovered in-situ were preceded with “HPC” for Holocene Plotted

Collection.

151

Several variables in the analysis are worthy of note:

(i) Understanding raw material characteristics is important because fracture

mechanics and tool type depend on the quality of raw material. In addition, it helps us

understand prehistoric ranging and mobility patterns and raw material procurement

strategies. The goals of raw material analysis in the present study were to: first compare

the raw material from flakes, cores, and tools from each unit; and second, seek to

quantify differences in ratios of cores to formal tools to angular fragments. In order to

avoid subjectivity in classification processes, the definitions used here were those that were recently developed and applied to variables in East Africa (Braun 2006; Gang 2001;

Tactikos 2005). Raw material is defined as any unmodified piece of lithic material that is morphologically suitable for modification into stone tools (Bradley 1975). Raw material identification was based on careful visual examination of color and the presence/absence of conspicuous crystals or phenocrysts. These identifications were also aided by macroscopic observation and comparison of characteristics from a comparative reference collection of known geologic sources in the Turkana basin such as those from the

Langaria Formation in the Surgei-Assile plateau (Braun 2006; Watkins 1981).

(ii) Classification of artifact assemblage generally included formal tools

specimens modified through retouch resulting in standardized typological and

technological tool types. Artifact type generally describes a general technological function of

the artifact classification (Isaac 1983). Debitage included whole flakes and angular

fragments that included unmodified fragments that could not be classifiable into any

established tool types. It also included tools exhibiting both utilization and 152

retouch/trimming. Examples of formal tools included burins; cores flaked cobles

Examples included burins, scrapers, crescents, and outils écaillés.

(iii) One of the important variables for understanding morphological changes in stone artifacts is size (Gang 2001). Shape can be understood in terms of three dimensions: length, width and thickness. In order to understand the changes in artifact morphology at my sites, the size of all (modified and unmodified) flakes was measured using a standard digital metric caliper. The relationship between length and width can provide important information about technological changes through time and space. Table

5.2 shows the sample size and relevant information about lithic artifacts from each site.

(iv) Another important variable were weathering patterns. This variable’s categories included: No patination, (no rounding or weathering), slight patination (slight rounding slightly weathered) and heavy patination (extreme rounding or weathering).

(v) The presence/absence of cortex is also another variable that I recorded; 3.5%

of artifacts had cortex on them. This variable was critical in inferring if the tools were

manufactured at the source or were procured as cobbles, transported, and then

manufactured at the site, (or in the case of obsidian, were manufactured using small

pebbles. The behavioral implications of these variables have been discussed in detailed

elsewhere (Braun 2006; Braun et al. 2009).

153

5.2 Lithic artifacts assemblage from GaJi 4

Tables 5.1 and 5.2 shows raw material and typological composition of stone

artifacts assemblage from GaJi 4. Based on the assemblage analysis, a significant pattern of artifacts and raw material composition can be noted. Chalcedony is the dominant raw material constituting 72.4% of the lithic assemblage. It should however be noted that the frequency of modified artifacts in each raw material category does not correspond to overall representation in assemblage. A total of 1123 lithic specimens were recovered,

76.5% of which exhibit modification either through use, trimming or backing. Overall, modified artifacts constitute a very small percentage of the assemblage. The rest of the raw materials were categorized as either angular fragments, or hammer stones and grinding stones except for chalcedony (see Table 5.3).

154

Table 5.1: Raw material percentages for lithic raw materials from archaeological research sites

Raw Materials Site Chalcedony Basalt Quartz Obsidian Others Total Percent (%) GaJi 4 761 116 36 154 56 1123 23.3 FwJj 25W 1999 66 24 411 7 2507 52.1 FwJj 5 419 159 36 57 3 674 13.9 FwJj 27 33 2 3 2 1 41 0.9 FwJj 25 278 41 20 117 17 473 9.8 Total 3490 384 119 741 84 4818 100 Percent (%) 72.4 7.9 2.5 15.4 1.7 100

155

Figure 5.1: Raw material percentages for lithic raw materials from all research sites

70 60 50 40 30 20

% of total raw material at sites material raw total % of 10 0 Chalcedony Basalt Quartz Obsidian Others Raw material groups

156

Table 5.2: Typological composition of stone artifacts assemblage from GaJi 4

Tool Type Total (n) Percent (%)

Shaped Tools (n=90) Microlithics 54 4.8 Outils écaillés 32 2.8

Scrapers 4 0.4

Debitage (n=996) Angular 264 23.5

fragments

Broken flakes 264 23.5 Whole flakes 468 41.7 Others (n=37) Cores 24 2.1

Ground stones 4 0.4 Hammer stones 9 0.8 Stone bowls 0 0.0 Total 1123 100.0 157

5.3 Lithic artifacts assemblage from FwJj 25W

A total of 2971 lithic artifacts were recovered for FwJj 25W located at Area 10 at

Koobi Fora (Figure 3.3). Information on raw material and typological composition of

the stone artifacts assemblage from FwJj 25W is presented in Table 5.1 and Figure 5.2.

Based on the recovered artifact assemblage, significant (X2 =0.58, P=0.05) patterns of

artifacts and raw material composition can be noted. Chalcedony is the dominant raw

material constituting 79.7 % of the lithic assemblage. Other raw material includes

obsidian 16.3%, basalt 2.3%, and quartz 0.9%. It should however be noted that the

frequency of artifacts in each raw material category does not correspond to overall

representation in assemblage. A total of 38.8% (n=2507) of lithic artifacts were made

from chalcedony. Aside from two prismatic blades, most of the artifacts of from GaJi 4 were small and nondiagnostic with cortical and non-cortical flakes. Shaped tools made from obsidian artifacts tended to be mirolithics, and the artifacts often show traces of cortex indicative of being created from pebble-size nodules. The lithic assemblage had sharp edges and no rounded patinaltion. Three pieces obsidian artifacts were in the form of shaped tools such as mirolithics, blades, and scrapers a characteristic trait of Pastoral

Neolithic blade industries, particularly during the latter half of the Neolithic sequence.

158

Figure 5.2: Raw Material composition of lithic artifacts recovered from site FwJj 25W

Raw Material Comapotion for FwJj 25W

Quartz Basalt

Obsidian

Chalcedoony

159

Table 5.3: Typological composition of stone artifacts assemblage from FwJj 25W

Tool Type Total (n) Percent (%) Formal Tools (n=80) Microlithics 65 2.2 Outils écaillés 14 0.5 Scrapers 1 0.0

Debitage (n=2875) Angular 2561 86.2 fragments Broken flakes 60 2.0 Whole flakes 254 8.5 Others (n=11) Cores 7 0.2 Ground stones 2 0.1 Hammer stones 2 0.1 Stone bowls 0 0.0 Total 2966 100.0 160

Table 5.4: Stratigraphic distribution of raw materials at FwJj 25W

Elevation Chalcedony Quartz Obsidian Basalt Other Surface-101.30 0 0 0 0 0 101.29-101.20 4 0 0 0 0 101.19-101.10 14 0 4 1 0 101.09-100.00 148 1 5 3 0 100.99-100.90 138 2 14 0 0 100.89-100.80 127 5 38 15 1 100.79-100.70 622 1 98 16 1 100.69-100.60 400 4 90 9 4 100.59-100.50 295 5 69 16 1 100.49-100.40 146 4 37 2 0 100.39-100.30 57 2 23 4 0 100.29-100.20 14 0 11 0 0 100.19-100.10 17 0 5 0 0 100.09-100.00 17 0 17 0 0 Total 1999 24 411 66 7 Percent (%) 79.7 0.95 16.3 2.6 0.3

161

5.4 Lithic artifact assemblage from FwJj 25

Information on raw material and typological composition of the stone artifacts

assemblage from FwJj 25 is shown in Table 5.5 and 5.6. Based on the recovered artifact

assemblage, significant (X2 =0.52, P=0.05) patterns of artifacts and raw material composition can be noted. Chalcedony was the dominant raw material constituting 54.6

% of the lithic assemblage. This figure is slightly lower than the amount of chalcedony that was recovered from other site. Additional raw material comprised of obsidian 20.4%.

It should however be noted that the incidences of formal tools in each raw material

grouping does not match up to overall representation in assemblage. The assemblage was

dominated by formal tools such as crescents, scrapers, blades 12.5% (Table 5.6).

Obsidian accounted for 20.4% of the lithic assemblages recovered, while Chalcedony

accounted for 54.6% of the lithics. 45.6 % of the recovered lithic finds preserve evidence of the cortex cobbles that these pieces were made from. The density of material at FwJj

25 is low (<30 artifacts per square meter). The presence of extremely small debitage suggests at least minimal post-depositional water transport of the artifact assemblages.

Among obsidian artifacts, microlithics and the artifacts often show traces of cortex indicative of being created from pebble size nodules. The other artifacts include a series of relatively nondiagnostic flakes that probably relate to the same production strategy.

162

Table 5.5 Typological composition for lithic artifacts from all the sites under investigation including FwJj 25

Sites Tool Types GaJi 4 FwJj 25W FwJj 5 FwJj 27 FwJj 25 Total

Formal Microlithics 54 65 14 3 43 179 tools Outils écaillés 2 14 8 0 25 49 Point Scrapers 32 14 9 0 25 80 Angular fragments 264 2561 370 10 162 3367 Debitage Broken flakes 264 60 150 10 62 546 Whole flakes 468 254 117 26 275 1138 Cores 0 0 0 0 2 2 Others Ground stones 4 2 8 0 14 28 Hammer stones 9 2 11 0 13 35 Stone bowls 0 0 0 0 0 0

Total 1097 2972 687 49 621 5424 163

Figure 5.6: Tool types and lithic raw material distribution from FwJj 25

Raw material types Tool Types Chalcedony Basalt Quartz Obsidian Others Total

Formal Microlithics 19 0 9 10 5 43 tools Outils écaillés 20 2 0 3 0 25 Point 1 0 0 1 0 2 Scrapers 9 2 1 8 1 21 Angular fragments 109 5 16 24 8 162 Debitage Broken flakes 32 5 4 15 7 63 Whole flakes 135 55 11 64 10 275 Cores 23 3 3 2 1 32 Others Ground stones 6 6 2 0 0 14 Hammer stones 0 3 4 6 0 13 Total 354 80 50 132 32 649 Percent (%) 54.6 12.4 7.8 20.4 4.8 100.0 164

5.5 Lithic artifacts assemblage from FwJj 5

Information on raw material and typological composition of the lithic artifacts assemblage from FwJj 5 is shown in Table 5.5 and illustrated in Figure 5.7. Based on the recovered artifact assemblage, significant (X2 =0.58, P=0.05) patterns of artifacts and raw material composition can be noted. Chalcedony is the dominant raw material constituting

61.2 % of the lithic assemblage. Other raw material includes basalt 23.5% obsidian 9.2% and 5.7% quartz. It should however be noted that the frequency of artifacts in each raw material category does not correspond to overall representation in assemblage.

Aside from formal tools (microlithics, scrapers and crescents) Plate 5.1, most of the artifacts from FwJj 5 are small in size and nondiagnostic with cortical and non-cortical flakes (see table. 5.7). Among obsidian artifacts, due to the small size of the available source material, artifacts tend to show traces of cortex indicative of being created from pebble-size nodules. Three pieces of obsidian artifacts were in the form of formal tools and debitage are a technological trait common among Pastoral Neolithic assemblages in east Africa. The other artifacts include a series of relatively nondiagnostic flakes that probably relate to the same production strategy.

165 Table 5.7: Typological and raw material composition at FwJj 5

Raw material types Tool Types Chalcedony Basalt Quartz Obsidian Others Total

Formal Microlithics 7 0 1 6 0 14 tools Outils écaillés 1 1 0 7 0 9 Point 1 0 0 0 0 0 Scrapers 2 0 0 1 0 3 Angular 306 20 7 17 0 350 Debitage fragments Broken flakes 15 110 20 4 1 150 Whole flakes 76 15 5 19 2 117 Cores 11 6 2 3 0 22 Others Ground stones 0 7 1 0 0 8 Hammer stones 0 2 3 6 0 11 Total 419 160 39 63 3 684 Percent (%) 61.2 23.5 5.7 9.2 0.4 100.0 166

5.6 Lithic artifacts assemblage from FwJj 27

This site is located Area 10 collection areas (Figure 3.2). An excavation was undertaken at FwJj 27 (see chapter 3) to recover human skeleton. A small number of lithic specimens were recovered. Although formal tools were relatively small, patterns of representation of different materials can be noted. Chalcedony is the predominant raw material constituting 88.6% while obsidian constitutes only 3.8% of total lithic assemblage. Chert and basalt are also represented. However the frequency of modified artifacts in each raw material category does not correspond to its overall representation in the assemblage. Of the 52 lithic specimens that were recovered 62.5 % of this exhibit modification either through backing or as cores. The rest of the lithics were classified as debitage and angular fragments (see Table 5.8).

167

Figure 5.3: Raw materials distribution for lithic artifacts at FwJj 27

100

Chalcedony Basalt

10 Quartz Obsidian Others % of total lithic assamblage

1 Raw Materials Types

168

Table 5.8: Typological and raw material composition at FwJj 27

Raw material types Tool Types Chalcedony Basalt Quartz Obsidian Others Total

Formal Microlithics 3 0 0 0 0 3 tools Outils écaillés 0 0 0 0 0 0 Point 0 0 0 0 0 0 Scrapers 4 0 0 0 0 4 Angular 8 0 2 0 0 10 Debitage fragments Broken flakes 10 0 0 0 0 10 Whole flakes 20 1 0 2 1 24 Cores 1 0 0 0 0 1 Others Ground 0 0 0 0 0 0 stones Hammer 0 0 0 0 0 0 stones Total 46 1 2 2 1 52 Percent (%) 88.6 1.9 3.8 3.8 1.9 100.0 169

5.7 Lithic Artifacts composition and intersite comparison.

A review of the lithic assemblages between sites suggests that variation between

sites is greater than the variation within assemblages. Although the full spectrum of variation is displayed in the entire assemblage, variation within the whole assemblage

seems to be confined to very tight range at around 60% of the original mass of cores. Yet

comparisons between assemblages do exhibit significant differences between

assemblages, for example assemblages from FwJj 25 and 25W and those from GaJi 4

(Table 5.9).

Interestingly enough, although there appears to be trends of increased reduction in

the flaked piece assemblages from FwJj 25 and 25W, these differences are not

significantly greater than GaJi 4 (ranked artifact type vs. raw material; Kendall’s Tau:

0.79; p=0.02). Furthermore there does not appear to be any major differences in the levels

of reduction exhibited in cores made from different raw materials within sites. This is

particularly evident at FwJj 25 and 25W. Levels of reduction recorded in the whole flake

assemblages made from obsidian suggested significant differences from other raw

material such as basalt, chalcedony and chert flakes, yet no such difference exists among

formal tool assemblage. Increased levels of reduction at GaJi 4 may be the result of

increased transport behaviors due to ecological conditions that favor the use of more

mobile toolkits. Previous studies have suggested variability among hunter-gatherer and herder populations (Eerkens et al. 2007; Lane et al. 2007; Prendergast 2008). These mobile toolkits may have provided the mechanism for mobility. Prior research has indicated that the nomadic lifestyle for both hunter-gatherer and herders could have contributed to their invisibility in the archaeological record (Sadr 2008; Smith 1991;

2005). The assemblage from my research sites represents the first attempt by herders to 170

culturally mediate resource acquisition either through increased mobility or exchange and

information networks. In that sense it is vital to understand energetic input of

technological organization because it should reflect the energetic benefits accrued from

stone tool procurement, production and use. Therefore, obsidian from Galana Boi

Formation assemblages form a very interesting case study because the different factors

that affect technological organization are well known (raw material availability and

quality) and ecological factors vary across space and time. There does not appear to be

significant differences in artifacts types and raw materials between FwJj 25 and FwJj

25W. However, it appears that FwJj 25 had more debitage than the rest of these other

sites. Microlithics are also among the most represented formal tools in all the sites (see

Figure 5.4a and 5.4b). These differences are even more evident between flake assemblages from later time periods such as at FwJj 5.

Results from chi-square analyses for raw materials are consistent with the results from the debitage assemblage (see Table 5.9). Most cores and tools are made from similar raw material. The numbers of local (source is less than 50 km) and exotic (source is more than 50km) cores are not significant although the numbers of cores vary across sites (Eerkens 2008). At FwJj 25W and GaJi 4 the core and tool analysis returned quite interesting results despite the a possible variation in obsidian procurement strategies,

FwJj 25 and 25W produced many cores that were made of local raw material. However formal tools made of local and non local materials were more abundant than those made of chalcedony. Chalcedony is a locally available raw material found in pebble and cobble from the riverbed deposits immediately adjacent to the sites. It is therefore hypothesized that exotic materials were procured and modified before being transported to the site at 171

FwJj 25 and 25W. As earlier mentioned at FwJj 25 and 25W and Gaji 4, 5% of the

obsidian and chalcedony had cortex, meaning that they might have been procured as

cobbles and transported and modified at the site. Or they were acquired as small pebbles.

This line of thought is supported by the analysis of debitage (angular fragments, broken flakes and whole flakes). Debitage analysis at all the sites returned the same results.

Regardless of raw material, debitage comprised 20-30 % of the assemblage at each site.

The relative ratio of obsidian cores to obsidian tools at all the sites produced correspondingly high frequencies; other raw materials produced low frequency of formal tools relative to their core frequency. This probably reflects the quality of stone available rather than the skill of the tool makers. That is, the locally available raw material such as basalt and quartz are mediocre to poor for knapping. While the fine grained raw material such as chalcedony and obsidian are good for knapping and making formal tools.

172

Table 5.9: Chi-square of raw material types at the studied archaeological sites

Sites Raw Materials GaJi 4 FwJj 25W FwJj 5 FwJj 27 FwJj 25 Total Chalcedony 761 1999 419 33 278 3490 21.8 57.3 12.0 0.9 7.9 72.4

67.8 79.7 62.3 80.4 58.7

Basalt 116 66 159 2 41 384 10.3 17.2 23.6 0.5 10.7 7.9

30.2 2.6 41.4 4.8 8.7

Quartz 36 24 36 3 20 119 30.3 20.2 30.3 2.5 16.8 2.4

3.2 1.0 5.3 7.3 4.2

Obsidian 154 411 57 2 117 741 20.8 55.5 7.7 0.3 15.8 15.4 13.7 16.4 8.5 4.8 24.7

Others 56 7 3 1 17 84 66.7 8.3 3.6 1.2 20.3 1.7

4.9 0.3 0.4 2.4 3.6

Column Total 1123 2507 673 41 73 4818 100.0 Percent (%) 23.3 52.1 13.9 0.9 9.8

Chi-Square Value D.F Significance Pearson 1279.0234 4 .0001 Likelihood ratio 1423.186 4 .0000

173

Figure 5.4a: Distribution of lithic artifact assemblages from research sites

10000

1000

100 GaJi 4

FwJj 25W 10 FwJj 5

Numberof lithic assemblage FwJj 27 1 FwJj 25

Measured variables

174

Figure 5.4b: Distribution of lithic artifact groups from all the studied archaeological sites

1000

100

GaJi 4 FwJj 25W 10 Number of tool types tool of Number FwJj 5 FwJj 27 FwJj 25

Lithic artifact groups

175

Table 5.10: Weathering stages for lithic artifacts from research sites

No Slight Heavy Site/ Nature of Patination Patination Patination Patination (%) (%) (%) GaJi 4 60.5 30.4 9.1 GaJi 4 82.1 12.5 5.4 FwJj 5 59.3 32.5 8.2 FwJj 27 56.1 33.4 10.5 FwJj 25 75.4 15.2 9.4

176

Plate 5.1: Microlithics recovered from FwJj 25W

177

CHAPTER SIX

Analysis of ceramic shards and other assemblages

6.1 Introduction

Pottery is one of the most important sources of information in archaeological studies. Worldwide, ceramic similarities are used to model cultural contacts and identities among prehistoric population not only because of their ability to provide cultural, chronological and chorological classification but also because of the abundance information about many other aspects of prehistoric lifeways (Keding 2000; Sadr 1998,

2008). Various streams of Bantu migrations in East Africa, for example, have been reconstructed on the basis of ceramic evidence (Chami 2007; Wandiba 1990).

Ceramics from each horizon were analyzed and recorded in their context with an emphasis on technological attributes, namely temper firing, finishing and decoration, vessel form and wall thickness. The ceramic assemblage from the sites under investigation was excavated and recovered, processed and cleaned using the methodological protocol described in the presiding chapter. Attributes for each pot shard was entered into relational database on the Microsoft Access platform and organized in a nested hierarchy through a system of linked user forms. The collected observations included the type (mineral, organic), size (small, medium, large) and frequency (rare, common, frequent) of tempering material, surface treatment

(burnishing, polishing, and color), vessel body parts (rim, bottom, wall), thickness, and 178

decoration. Frequency, roundness, angularity, and size of both mineral and organic

inclusions were recorded according to estimation charts by Orton et al. (1993: 238–

239). The database integrated the hierarchical system of classification of decorations devised by Caneva (Caneva 1988; Caneva and Marks 1990), including decorative techniques (rocker, alternately pivoting stamp, simple impression, incision), implements

(evenly, unevenly serrated, scraping comb, double pronged, stylus and plain edge),

elements (dots, dashes and lines), motifs, (straight, curved, packed, spaced zigzags,

paired and single lines), and structure (continuous, banded, paneled and dotted wavy

lines). This classificatory system has been applied by various scholars to various North

and West African ceramic assemblages, namely esh-Shaheinab, Sudan; Adrar Bous,

Niger; and Gobero, Niger, Wadi Howar, Chad (Garcea and Caputo 2004; Garcea 2006,

2008; Keding 2000; Sereno et al. 2008). Because this system offers open guidelines for

describing technical processes employed in pottery decoration, it could be successfully

applied to the Turkana assemblages in this study. It should however be noted that

detailed discussion on the implications of ceramic analysis was outside the scope of this

study and will therefore be presented elsewhere (Keding et al. in prep).

In this chapter, other materials that were recovered these from the excavated

sites namely eggshells Beads (OEB) will briefly be described. In East Africa there are no universally accepted protocols for analyzing OEB beads excavated from the Koobi Fora

Holocene archaeological sites. In my analyses of OEB the following criterion developed by Smith (1991) were used. The goal of this analysis was to determine differences in abundance of bead sizes and possible manufacturing techniques. Data obtained from 179 the analysis of other miscellaneous artifacts was recovered included, brief description size raw material used technique manufacture.

6.2 Ceramic assemblage from GaJi 4

Ceramic assemblage from GaJi 4 includes the typical Nderit ware and Ileret ware fabrics first described by Barthelme (1985), Nelson (1993). A significant portion of the pot shards recorded from GaJi 4 was not well-fired and friable. The shards had a gritty texture due to a large amount of mineral inclusions, mainly of quartz and feldspar; 75% of the ceramic finds were usually sand-tempered, but could also include mica and plant tempers. The size of inclusions varied from very coarse (>2 mm) to medium (1–2 mm).

Mineral tempers usually have a high degree of angularity, suggesting that aeolian sand was not a common tempering material. A thin layer of fine clay was applied on the surfaces as a self-slip. Fresh fractures show either completely dark gray or brown colors, or, alternatively, gray oxidation zones with reddish cores, indicating that firing was done for a short period and/or at low temperatures (Nordström 1972). Although rim shards were too small to allow an exact determination of vessel diameters, their slight degree of curvature is suggestive of large bowls. Wall thicknesses ranged from 4mm to 26 mm.

However, the greater part ( 72.4%) measure between 6 and 10 mm, with a peak between 7 and 9 mm. Very thick (>11 mm) storage jars are also present, as well as heavy duty storage vessels (>15 mm) (Figure 6.1). Rims often show milled and notched impressions, similar to those recently reported by Garcea and Hildebrand (2009; Keding 180

2000; Gatto 2002) at the Sai Island in the Sudan, Wadi Howar region in Eastern Sahara

and the Nabta and El Jerar complexes in the Egyptian Western Desert respectively.

Where decorations occur, they are banded rather than continuous. Dotted wavy line

bands often display symmetrical waves to form a series of specula semicircles (Plate

6.1). Waves could be either long or short plate 6.1. Combs used to make dotted wavy line and other motifs could not be conclusively determined. How many teeth for were used example per comb could not be ascertained because they were in small fragmented pieces.

181

Table 6.1: Ceramic decoration motifs at GaJi 4

Decoration motif No, of shards Percent (%) Nderit ware 128 16.0 Burnished/Slipped 216 27.1 Other Decorated 59 7.4 Disc 26 3.3 Undecorated 364 45.6 Internally Scored 2 0.3 Handles 3 0.4 Total 798 100.0

182

Figure 6.1: Wall thickness of shards recovered from GaJi 4

Wall Thickness at GaJi 4 180 156 160 134137 140

120 100 75 76 80

No, of shards No, 60 36 42 42 40 25 16 21 22 8 20 3 2 1 2 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Wall thickness (mm)

183

6.3 Ceramic assemblage from FwJj 25W

The Ceramic shards that were collected from FwJj 25W included the characteristic

Nderit and Ileret wares fabrics mentioned above (Barthelme 1985, Nelson 1993). It is still not clear where these ceramic traditions originated, but it is believed to have originated from the north more likely in the southern Sudanic region, or to a lesser degree in southwestern Ethiopia. The pot shards had a coarse consistency due to a hefty amount of mineral tempering, most of the finds were usually sand-tempered, but could also include mica and plant tempers. The size of inclusions varies from very coarse

(>2 mm) to medium (1–2 mm). Mineral tempers usually have a high degree of angularity, suggesting that aeolian sand was not a common tempering material. A thin layer of fine clay was applied on the surfaces as a self-slip. Fresh fractures show either completely dark gray or brown colors, or, alternatively, gray oxidation zones with reddish cores, indicating that firing was done for a short period and/or at low temperatures (Nordström 1972). From the minor degree of curving on shards, it could be determined that vessel shapes included open large bowls with straight walls. Wall thicknesses range from sizes (2.5-18 mm). However, a large number of them ( 74.3%)

measure between 6 and 10 mm, with a greatest between 6 and 9 mm. Very thick (>11

mm) storage jars are also present, as well very thick (>16mm) which perhaps used as

heavy duty storage vessels.

46.2% of the ceramic shards from FwJj 25W were undecorated (Table 6.2). Where decorations occur, they are banded rather than continuous. Dotted wavy line bands often display symmetrical impressions to appear like a sequence of specular arcs (Figure 184

6.2). In a few cases did motifs only resemble the real technique of dotted wavy line impressions and recall arch-shaped motifs.

185

Table 6.2: Ceramic assemblage recovered from FwJj 25W

Decoration No, of Percent (%) No, of Shards Percent (%) Shards (Excavated) ( surface) ( surface) (Excavated) Rim Decorated 58 1.8 10 9.4 Rim Undecorated 72 2.2 15 14.2 Body. Decorated 571 17.5 30 28.3 Body 2260 69.2 45 42.5 Undecorated Red Slip rim 151 4.6 0 0.0 Red slip Body 57 1.7 0 0 deco Red Slip body 76 2.3 0 0 undecorated Internally Scored 8 0.2 5 4.7 Disc 13 0.4 0 0 Handles 0 0 1 0.9 Total 3266 100.0 106 100.00 186

Figure 6.2: Wall thickness of ceramic shards recovered from FwJj 25W

Wall Thickness at FwJj 25W 700 654 600

500 451 456 395 400 300 259251 No, of shards No, 200 105 75 98 102 90 95 84 100 56 56 16 26 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Wall thickness (mm)

187

6.4 Other finds from FwJj 25W

Other finds that were recovered from FwJj 25W include ostrich eggshell beads at various stages of production the diameter. FwJj 25W comprised of 7 complete beads, 5 broken pieces and 254 shell fragments. Measures of central tendency were computed to

summarize the data for the ostrich eggshell beads sizes. The measures of central

tendency were as follows; mean was 2.4mm; the range was 1.2 whereas the median was 2.7mm and the mode 2.5mm. Measures of dispersion were also computed to

understand the variability of scores for the eggshell bead diameters as the standard

deviation was 0.3. There was no variability between the diameters among these ostrich

eggshell beads.

Other finds included fragmented pieces of red ochre. The appearance of ochre

has been documented at most Pastoral Neolithic site in east Africa and southern Africa

(Ambrose 1998; Marshall 1986; Mutundu 2010; Smith 1992).

6.5 Ceramic assemblage from FwJj 25

A total of 116 pieces of pots shards were recovered from FwJj 25, representing

16.02% of the total excavated assemblage. Surface sampling yielded a total of 54 shards

representing 16.02% of surface assemblage. No complete vessels were recovered

probably due to compaction by the sediments as opposed to latter disturbance. More

than 90% of the excavated shards depicted good edge preservation, an indication that

the finds had not undergone some form of fluvial transport. None of the recovered was 188

able to refit. Shards with smooth circular perimeter frequently occur sometimes with a

central hole. These shards were probably used as pendants as such pottery has been

reported from other sites in the Sudanic area Caneva (1988). All these shards may have

been used as rubbers for modeling and more probably for scrapping and smoothing. The

inner parts of the pots were carefully polished with traces of finishing.

The decoration was varied and covers most of the surface except when at the very

bottom of the pot. Although decoration in the inside of the pot was only noticed among

the Nderit ware pottery and even so was limited to the upper part of the open bowls.

Since up to now no complete vessel has been recovered from the excavations,

shapes can only be constructed from the potshards. From this site it seems that the

favorite bowl was the hemispherical bowl although more cylindrical and more spherical

pots were made all with a rounded base. Some bottom parts were not only thicker than

part of the pot but were somehow conical and hemispherical and of considerable

thickness. It is assumed from the coil manufacturing techniques was used in the

production of these vessels.

Rims were usably simple or slightly thinner than the rest of the pot. 2.5% of

these rims were decorated with indentations but is some cases it is only certain parts.

Whether these fragments should not be considered as combs for pottery decorations remains to be seen. The almost absence of repair holes is surprising as it suggests that the pots were not reused.

The wall thickness appears to vary according to the size of the pot probably according to the distance from the base, although shards usually show a uniform 189

thickness (Figure 6.3).Wall thickness range from 8-10mm but shards up to 6mm and 12 mm thick occur. Perhaps of the thicker walls were associated with globular shapes and

thinner walls with cylindrical shapes. This would probably have a functional implication

beyond the scope of this study. Other characteristics such as sprout mouth and neck

and handle were noted. The size as far it can be detected from the curve of the walls

varies from 25 to 45mm max diameter and around 15mm for vessels.

As far as decoration is concerned it cannot be said that any specific motif was

significantly associated with a particular shapes, sizes or thickness. But what happens to be certain is that the finer, thinner pottery corresponds to carefully make regular decorations. This feature might tentatively be associated with the cylindrical pots while wayline motifs seems to be preferred for globular forms.

Clay (paste) was usually quartz tempered and sometimes with organic matter the only visible differentiations that some tempering was present. This paste does not however appears to be associated with a particular decoration technique as it has been reported elsewhere. It is excluded from the wavy line motifs (Arkell 1949; Caneva 1988).

Fracture color depends on firing temperatures which means that it varies on the various parts of the pot according to the place in the furnace. A great variety of colors were represented ranging from reddish to gray brown. Surface color ranges from cream to light brown always with a pink to reddish shards and usually very different on the inside from the outside. 25% of shards from this site bear spots of different color due to the oxidation because of the contact positions. 190

Although the complete shapes are absent and since the shapes encountered are extremely simple and homogeneous, the most distinctive trait of this pottery is the decorations.

It should however be noted that due to the limited dataset of the ceramic shards recovered from FwJj 27, limited analysis were undertaken hence no claims of their behavioral implications are made here. However table 6.5 show the distribution of ceramic shards recovered from FwJj 27.

191

Table 6.3: Excavated and surface collected ceramic assemblage from FwJj 25

Decoration No, of Percent No, of shards Percent shards (%) (Surface) (%)

(excavated) Rim Decorated 25 21.6 13 24.1 Rim Undecorated 16 13.8 8 14.8

Body. Decorated 38 32.8 17 31.5 Body 36 31.0 14 25.9 Undecorated Red Slip rim 1 0.9 1 1.9 Red slip Body 0 0.0 0 0 decorated Red Slip body 0 0.0 1 1.9 undecorated

Internally Scored 0 0.0 0 0 Disc 0 0.0 0 0 Handles 0 0 1 1.9 Sub Total 116 100.0 55 100.0 192

Figure 6.3: Wall thickness of shards recovered from FwJj 25

Shards wall thickness at FwJj 25

50 46 45 43 39 40

35 30 25 20 15

No, of shards No, 15 10 6 7 4 4 3 5 1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 Wall thickness (mm)

193

Table 6.4: Types and temper proportions on ceramic shards recovered from study sites.

Temper Type Percent Percent Percent Percent Percent (%) at (%) at (%) at (%) at (%) at GaJi 4 FwJj 25W FwJj 5 FwJj 27 FwJj 25 Quartz, round (sand) 28 25 15 0 10 Quartz, angular (crushed) 40 15 35 0 45

Mica 10 13 9 0 8

Plants 15 13 13 0 7 Limestone 5 11.4 5 0 9

Bones 1 21 21 0 19 "Shale" 0.4 0.2 0.6 0 0.6 Iron containing 0.3 0.8 0.8 0 0.8 compounds Grog 0.2 0.1 0.1 0 0.1

Miscellaneous 0.1 0.5 0.5 0 0.5

194

6.6 Ceramic assemblage from FwJj 5

No complete vessels were recovered from this site; this was probably due to

sediment compaction as opposed to latter disturbance. And as others (Garcea and

Hildebrand 2009; Cavena 1983) have argued, lack of complete pot in such sites could be

as a result of short term occupation.

Besides the large amounts of the ceramics shards that were recovered (n=500).

A number of potshards were able to refit, but the majority could not refit because the

edges of some of the pot shards had been braided probably for the purpose of reuse.

Shards with smooth circular perimeter frequently occur sometimes with a central hole

have been reported at Pastoral Neolithic at Koobi Fora (Barthelme 1985, Nelson 1993)

and beyond including the Sudanic area (Cavena 1983; Garcea and Hildebrand 2009).

These shards were probably used as pendants. All these shards may have been used as rubbers for shaping and more probably for scrapping and smoothing as it has previously been suggested ( Arkell 1941; Caneva 1988; Keding 2000).The inner part of the pots were carefully polished to the with fine traces of finishing. The outside sometimes shows traces of finishing.

The decoration were varied as it covers most of the surface except when there very bottom of the pot. Decoration in the inside of the pot was only noticed among the

Nderit pottery and even so limited to the upper part of the open bowls. Since up to now no complete vessel has been recovered form the excavations, shapes can only be constructed form the potshards. From this site, it may seem that the favorite vessel was 195

the hemispherical bowl although more cylindrical and more spherical pots were made

all with a rounded base. Some bottom parts were not only thicker than part of the pot but were somehow conical and hemispherical and of considerable thickness. It is assumed that the coil manufacturing techniques was used in the production of these vessels. Rims were usably simple and or slightly thinner than the rest of the pot. 2.5% of

these rims were decorated with indentations but is some cases it is only certain parts,

whether these fragments should not be considered as combs for pottery decorations.

The almost absence of repair holes is surprising as these is a common feature that has

been reported from Pastoral Neolithic sites.

The wall thickness appears to vary according to the size of the pot probably

according to the distance from the base, although shards usually show a uniform

thickness. Wall thickness range from 8-10mm but shards up to 6mm ands 12 mm thick

occur. Perhaps of the thicker walls were associated with globular shapes and thinner

walls with cylindrical shapes. This would probably have a functional implication beyond

the obvious. Other characteristics such as sprout mouth and neck and handle were

noted. As far it can be detected from the curve of the walls varies from 25 to 45mm max

diameter and around 15mm for vessels.

As far as decoration was concerned one cannot say that any specific motif was

significantly associated with a particular shapes sizes or thickness. But what appears to

be certain is that the finer , thinner pottery corresponds to carefully made regular

decorations might tentatively be associated with the cylindrical pots while wayline

motifs seems to be preferred for globular forms. 196

The clay (paste) was usually quartz tempered and sometimes with organic

matter the only visible differentiations that some or tempering was present. This paste

does not however appears to be associated with a particular decoration technique as it has been reported elsewhere it is excluded from the wavy line motifs (Arkell 1943;

Caneva 1984)

Fracture color depends on firing temperatures which means that it varies on the

various parts of the pot according to the place in the Kiln. A great variety of colors were

represented ranging from reddish to gray brown. Surface color ranges from cream to

light brown always with a pink to reddish shards and usually very different on the inside

from the outside. Many shards bear spots of different color due to the oxidation

because of the contact positions.

Although the complete shapes are absent and since the shapes encountered are

extremely simple and homogeneous, the most distortive trait of this pottery is the

decorations. I have already indicated that the polishing and burnishing was applied to a

very small number of the shards. I therefore argue that the potter wanted to have an

corrugate interior the other surface while a smooth fairly impermeable interior was

preferred.

The undecorated fragments account for 23.9% of the total ceramic assemblage

at most of the levels with very few rim shards .Site FwJj 5 shows a slightly higher

percentage against the smaller percentage of site GaJi 4. It is possible that some of the

undecorated shards were either from the base or the shoulder; the rate of undecorated

pots goes down even to about 5%. 197

Table 6.5 Excavated and surface collected ceramic assemblage from FwJj 5

Decoration No, of Shards Percent No, of Shards Percent (Excavated) (%) ( Surface) (%) Rim 6 2.7 11 3.9 Decorated Rim 8 3.6 20 7.1 Undecorated Body. 60 27.3 20 7.1 Decorated Body 141 64.1 215 76.8 Undecorated Red Slip rim 1 0.5 0 0 Red slip Body 0 0.0 0 0 deco Red Slip body 2 0.9 0 0 undecorated Internally 0 0.0 1 0.4 Scored Disc 2 0.9 3 1.1 Sub Total 220 100.0 270 100.0 198

Figure 6.4: Wall thickness of shards recovered from FwJj 5

Wall Thickness of sherds at FwJj 5 120 96 100

80 80 69 64 60 52 54

32 No, of shards No, 40 16 20 7 9 6 6 4 1 2 1 1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Thickness (mm)

199

6.7 Conclusion

In conclusion therefore, it can be said explanations for the observed distribution of archaeological material at the GaJi 4 may have involved episodes of reoccupation through time but range from occupation by mobile populations. It has been suggested

(Garcea and Hildebrand 2009; Garcea 2006; Brooks 2006; Hoelzmann et al. 2001;

Marshall 1986) that some of this Mid Holocene sites represent short term reoccupation by variable and mobile populations. There are clear land use patterns at the GaJi 4 which being based on mobility patterns and subsistence system are likely to have changed over time and have direct bearing on variability and mobility patterns among mid Holocene herders and foragers ( Prendergast 2008; Robbins 2006; Marshall 1986).

As aridity continued during the mid Holocene, resources at the inland became scarce, emerging wetlands from the receding lake becomes a valuable resource. Where as present day pastoral communities in Lake Turkana Basin cannot be used as direct analogues of mid Holocene pastoral communities, during drought, modern day populations in the Turkana Basin congregate at the lake shore areas to take advantage of pasture and aquatic resources as well as wildlife (Gifford-Gonzalez 1985; Kiura 2005,

2008; Per Obser). During the wet season however it appears to be less returns in staying at the lake shore and populations move inland as water and pasture is generally available and herds of wildlife are scattered all over the landscape. It does appear therefore that it is the patchiness and timing of resource availability which are important factors in animal and human use of these lacustrine environments.

200

There are numerous possible cultural explanations for the co-occurrence of these

pottery traditions, all rather speculative: for example, occupants concurrent with or

postdating the Pastoral Neolithic ceramics might pick up older pottery on the landscape, as suggested elsewhere by Musonda (1987). On the other hand, Holocene occupations could be very short, leading to accumulation of material remains in a very thin horizon; but this seems unlikely given the volume of sediment containing the shards. Finally,

ceramic traditions may have been mixed through exchange, but only if Nderit pottery at

Koobi Fora is older than previously thought as it has been argued by Bower (1991).

This chapter has highlighted at length on the various ceramics finds that were recovered from the sites under investigation. In addition to this chapter has also endeavored to address the behavioral implication associated with this ceramics. Chapter

8 will be returning to this topic so as to tie with the broader goals of this multidisciplinary project. Clearly a lot remains so as be done in order to understand fully underhand the substance mobility and exchange and contacts among this prehistoric herders and foragers.

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Plate 6.1: Ceramics from study sites

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CHAPTER SEVEN

Obsidian survey, sourcing and geochemical characterization

7.1 Introduction

This chapter outlines methods, of survey, sourcing and geochemical characterization of for both geological and archaeological obsidian artifacts. Obsidian sourcing and characterization was the main focus on this dissertation. Here, I first discuss the protocol of survey, sourcing and the laboratory techniques for both XRF and

LA-ICP-MS. I then present the results from each of the two analytical techniques. Finally

I discuss the comparison of the various results from different sites taking into account the overall goal of the project.

7.2 Obsidian Sourcing Surveys

During the initial phases of this multi-disciplinary project, working with Drs.

Carolyn Dillian (Coastal Carolina University) and David Braun (University of Cape Town), we begun a pilot survey of obsidian sources in Koobi Fora, which was gradually expanded to the scope of the project reported here. The initial focus of the field survey was to systematically relocate and map the known obsidian sources that had previously been reported in Eastern side of Lake Turkana Basin (Braun et al. 2009; Merrick and

Brown 1984; Watkins 1981). Additional survey was conducted to locate new obsidian sources as the archaeological samples indicated the presence of unknown sources. My targeted sourcing survey extended from Suguta Valley at the southern end of Lake

Turkana Basin, into the Eastern margin of the Surgei-Asille plateau up to the Kenyan- 203

Ethiopian border (Figure 7.1). The justification for this eastern basin-scale investigation

was that nearly all Turkana Basin obsidian artifacts do not match those from the better

documented Central Rift Valley’s sources (Merrick and Brown 1984, Ndiema et al. 2010;

Coleman 2008) and sources that have been characterized from central Ethiopia

(Negash et al. 2007; Negash and Shackley 2006; Negash et al. 2006). The Lake Turkana

area and southern Ethiopia have not been systematically surveyed. Since it is likely that

procurement of the obsidian used in the Turkana basin artifacts comes from either a

local or from an Ethiopian source., By exhaustively sampling specific localities on the

Kenyan side of the basin, any obsidian that will remain unidentified may be assumed to

come from Southern Ethiopia or parts of the Southern Sudan (Harvey and Grove 1982)

or unsurveyed areas of Kenya.

Geological report numbers 42, 44, and 47 issued by the government of Kenya

Ministry of Environment and Natural Resources, Mines and Geological Department were

used during this sourcing survey. Although the geological reports did not identify

sources between Baringo and East Turkana, they were useful in identifying volcanic

centers with trachytes and rhyolites that are often associated with obsidian. Published

references were also used to guide the obsidian targeted source surveys (Braun 2006;

Kirkwood 1981; Merrick and Brown 1984; Merrick et al. 1994; Watkins 1983), along with high resolution satellite imagery (IKONOS Quick bird), Digital Elevation Models (ASTER

DEM), and knowledge of local inhabitants. The localities from which I have been able to collect and/or analyze samples are listed in Table 7.1. Obsidian sources exhibit considerable inter-source variability (Glasscock et al. 2007; Neff 2003). The samples 204 were selected to cover the geographic extent of and any obvious physical differences in the sources.

Handheld GPS units were among the tools used to identify the coordinates of the samples locations. UTM coordinates were recorded using the WGS 1984 projection system.

205

Tables 7.1: Localities from which obsidian geological reference samples were collected

UTM 37N, WGS 1984 Obsidian locality Northing Easting Description Shin 220914 485520 Contemptible quality Surgei 1 223478 485868 Contemptible quality Small low quality Surgei 2 212660 484106 pebbles North Island 172080 449563 Mostly artifact quality Suguta 223777 239709 Dark, artifact quality 206

Figure 7.1: Obsidian sources that were samples for this study at Lake Turkana basin

207

7.3 Geochemical characterization and analytical procedures used to

characterize obsidian

Although other raw materials were used for stone tool manufacture, this research focused on obsidian because it has a restricted spatial distribution. Previous research on sourcing and geochemical fingerprinting of artifacts has shown that macroscopic identification of raw materials is subjective and likely to result in misclassification of artifacts (Braun 2006; Braun et al. 2009; Calogero 1992; Hermes et al. 2001). A variety of physical, optical, petrographic, and chemical attributes are used to "fingerprint" obsidian sources and artifacts. It should however be noted that the techniques used in discriminating sources in one region may not be useful in discriminating samples from another region of the world (Shackley 1995, 1998; Tykot 1997). Second, obsidian characterization is at times a matter of statistical probability as opposed to certainty because all sourcing studies are probabilistic (Shackley 1998; Eerkens and Rosenthal

2004). A number of analytical methods are now readily available and widely used

(Shackley 1998, 1995; Glascock 2002; Tykot 1998). Analytical techniques that are commonly used include Inductive Neutron Activation Analysis (INAA), Energy Dispersive

X-ray Florescence (ED-XRF), Scanning Electron Microscopy (SEM), and Laser Ablation

Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) among others. The quality of archaeological data resulting from each of these applications has continued to improve. Recent analytic advancements now allow archaeologists to discriminate 208 related but discrete signatures derived from distinct source zones (Shackley 1998).

Below I present a discussion of the analytical component of the methods for my analysis and a brief comment on the merits and demerits of each method. Finally I shall take a position, justifying the techniques that I chose were ideal in an area such as Koobi Fora where limited previous research has taken place and base reference materials are still lacking.

7.4 ED-XRF – Laboratory Procedures and Instrumentation

This study employed the use of non-destructive and minimally destructive

Energy Dispersive X-ray Florescence (ED-XRF) to analyze the geochemical proveniences of artifacts and geological source samples. ED-XRF is well recognized as a tool for qualitative and quantitative determination of major and minor elements in a wide range of sample types. The principle behind ED-XRF is that all elements absorb and emit radiation at specific and characteristic wavelengths (Sharma, 2006). Typical spectra for

ED-XRF Spectrometry appear as a plot of Energy (E) versus the Intensity (I). The concentration of element being determined is proportional to the intensity of its concentration wavelength. A typical XRF consists of an x-ray source, a detector and an analyzer. The spectroscopic techniques are used in measuring the absorption and emission of characteristic radiation, in this way an element is identified by its characteristic radiation and the spectroscopic technique may be used for its quantitative measurements. Computer analysis of these data yields an energy spectrum which defines the elemental composition of the sample. Essentially, the energy of the peak 209

gives the element identification, and the number of X-rays counted in the peak gives the

amount of the element present in the sample. There is a wide variation in ED-XRF

machines, the traditional model uses(d) CD 109 and Fe -55 radio isotope sources and a

Silicon lithium detector Si(Li) across a Be window. The spectra are collected using

Canberra Multi channel analyzer through a Canberra 2020 signal amplifier. Advances in

computer technology has brought into the market new models such as FISCHER 1000C

and EX-6600 energy dispersive x-ray fluorescence (ED-XRF). Other types of XRF

machines include Innov-X Systems portable, handheld ED-XRF, which test samples in the

field. The energies of the X-rays emitted by the sample are measured using a Si-semi-

conductor detector and are processed by a pulse height analyzer. Handheld, field

portable ED-XRF units bring into the discipline a lot of flexibility in that it can be taken

directly to the sample as opposed to bringing the sample to the analyzer and configuring

it to fit in an analysis chamber.

ED-XRF was chosen for this study because unlike aqueous elemental analyses that typically require destructive and time-consuming specimen preparation, often

using concentrated acids or other hazardous material, XRF spectrometry does not

destroy the sample and requires little, if any, sample preparation. It has a very fast

overall analysis turnaround time (Gratuze 1999). In addition, ED-XRF spectrometry easily

and quickly identifies and quantifies elements over a wide dynamic concentration range,

from parts per million to (ppm) levels up to virtually 100% by weight (% wt). These

factors lead to a significant reduction in the per sample analytical cost when compared

to other micro-element sampling techniques. It should however be noted that the fitting 210 level must be very accurate. Incorrect fitting function results in considerable bias in the estimates of the peak areas (systematic errors) especially for small peaks in the vicinity of large ones. ED-XRF is therefore, ideal for the measurement of major and minor elements thus a preferred technique for whole rock characterization (Shackley 2005;

Goffer 1980).

ED-XRF is also well suited for semi-quantitative determination of element content in complete unknowns as is the case at my research site. Typically free from sample preparation requirements, ED-XRF as technique has broad appeal to archaeologically oriented research. Because of its non-destructive nature, ED-XRF is widely applied with much success in artifact provenance studies. Specific aspects of ED-

XRF hinder straight forward analytical use. ED-XRF analysis is restricted to high field strength elements such as Sr, Rb, Y, Nb, Zr (Shackley 1998). Sample matrices also create spectral interference. Peak overlap is especially a problem for ED-XRF. In ED-XRF

Spectrometry, the primary interference is from other specific elements in a substance that can influence (matrix effects) the analysis of the element(s) of interest. ED-XRF also does not provide information on the chemical state of the element. Fluorescent X-rays can be easily absorbed by the sample itself (self-absorption). It is therefore important that the sample matrix match as closely as possible to that of the calibration standards.

If this is not possible, then empirical correction factors must be applied (Goffer 1980). It should however be noted that these interferences are well known and documented, instrumentation advancements and mathematical corrections in the system's software can easily and quickly be corrected. In certain cases, the geometry of the sample can 211

affect XRF analysis, but this is easily compensated for by selecting the optimum

sampling area, grinding or polishing the sample, or by pressing a pellet or making glass

beads. The lower energy XRF emission means that they have less penetrating power and hence less sensitivity. Advancements in computing techniques can now be combined with the physics of XRF using appropriate mathematical tool to solve some of the inherent drawbacks of ED-XRF. Figure 7.2 shows a schematic representation of ED-XRF

machine.

For this research, the following machine specifications were used. Also outlined

are detailed analytical procedures that were used. This method is particularly good at determining trace element composition of whole samples (Latham et al. 1992; Hermes and Ritchie 1997; Hall and Kimura 2002; Hermes et al. 2001). The non-destructive semi- quantitative dataset was produced using whole rocks (artifacts, primary sources and secondary sources). This non-destructive technique followed a strict protocol to minimize inherent problems that decrease precision and accuracy. To lessen the effect of matrix sticking on the artifacts, samples were cleaned in an ultrasonic bath for 3 minutes to remove the possibility of adhering matrix that would have confounded results. Samples that were collected from large archaeological assemblages were placed on a number grid and random number generator used to pick samples so as to minimize biases (Eerkens et al. 2007). Whole rock samples were irradiated for 300 seconds. Each sample was analyzed whole. In order to minimize sampling bias equal proportions of retouched tools, large debitage, formal and angular fragments were sampled (Eerkens et al. 2007). The trace element analyses were performed at the Archaeological X-ray 212

Fluorescence Laboratory at the University of California, Berkeley, using a

Spectrace/ThermoNoran™ QuanX energy-dispersive X-ray fluorescence spectrometer.

The spectrometer is equipped with an air-cooled Cu X-ray target with a 125 μ m Be

window, an X-ray generator that operates in the range 4–50 kV/0.02–2.0 mA at 0.02

increments, using an IBM PC based microprocessor and WinTrace™ reduction software.

The X-ray tube is operated at 30 kV/0.14 mA, using a 0.05 mm (medium) Pd primary

beam filter in an air path at 200 s live time to generate X-ray intensity K α -line data for

the elements titanium (TiO 2), manganese (MnO) and iron (as Fe 2 O 3 T) and, using the

L α line, rubidium (Rb), strontium (Sr), yttrium (Y), zirconium (Zr) and niobium (Nb).

Major and trace element intensities were converted to concentration estimates by employing a least-square calibration line established for each element from the analysis of international rock standards certified by the National Institute of Standards and

Technology (NIST), the United States Geological Survey (USGS) and the Centre de

Recherches Pétrographiques et Géochimiques in France (Govindaraju 1994). Line fitting is linear (XML) for all elements except Fe, where a derivative fitting is used to improve the fit for the high concentrations of iron and thus for all the other elements. Further details concerning the petrological choice of these elements in obsidian are available in

Shackley (1995, 1998, 2005; Hughes and Smith 1993).

The data from the WinTrace software were translated directly into Excel for

Windows for manipulation and then on into PAST for statistical analyses. In order to

evaluate these quantitative determinations, machine data were compared to

measurements of known standards (RGM-1) during each run. RGM-1 was analyzed 213 during each sample run for obsidian artifacts and sources to check the machine calibration; these data are presented below.

214

Figure 7.2: Schematic representation of ED-XRF machine

215

7.5 Laser Ablation Inductively Coupled Mass Spectrometry (LA-ICP-MS)

Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) is a

sensitive analytical method for rapid multi-element determination in the trace and

ultratrace range of geological, ceramic and radioactive solid sample materials and

technical products. The general operations of LA–ICP–MS, i.e. the type of laser, ablation

cells and transfer line, will be briefly addressed in this section. For detailed discussion

on the technical aspect of LA-ICP-MS please refer to Becker (1999), Durrant (1999),

Hattendorf (2005) and Russo et al. (2002).

In LA-ICP-MS, a sample is directly analyzed by ablating it with a pulsed laser beam. The created aerosols are transported into the core of inductively coupled argon plasma (ICP), which generates temperature of approximately 8000°C. The plasma in LA-

ICP-MS is used to generate ions that are then introduced to the mass analyzer. This exciting and highly sensitive analytical technique is incredibly versatile. In theory, any solid material can be analyzed provided the laser can couple with the material, as long as external standards are available, and internal standards are known (Resano et al.

2008). These ions are then separated and collected according to their mass to charge ratios. The constituents of an unknown sample can then be identified and measured.

This therefore, means that LA-ICP-MS offers extremely high sensitivity to a wide range of elements. The use of a laser in LA-ICP-MS archaeological research allows geochemical analysis of small, solid samples to be accomplished. The potential of LA-ICP-MS has been

applied with great success in various works to establish the definite origin and source

areas of the artifacts (Bugoi et al. 2004; Gratuze 1999). Figure 7.3 shows the 216

instrumentation set up for LA-ICP-MS. Compared to other micro sampling analytical techniques, LA-ICP-MS has several distinct advantages. Its major advantage being that

29 trace and Rare Earth Elements (REE) can be analyzed in a very short time, without any sample manipulation. In particular, concentrations of Rb, Sr, Y and Zr, some of the most sensitive indicators for discriminating obsidian sources, and often used as source identifiers can be determined with enough accuracy and sensitivity to allow confident provenance conclusions. LA-ICP-MS provides highly sensitive results detection limits

range from a few tenths of parts per million (ppm) to some parts per billion (ppb) for

this study parts ppm was used. Moreover, a large number of elements can be

determined. Analysis of solid samples is direct and requires no lengthy dissolution

processing which may be incomplete and can also potentially introduce contamination

to the sample. Analysis of solid samples by LA-ICP-MS requires little preparation (a flat surface may be required if the entire sample is to be probed). Laser probing utilizes light rather than charged particles and can, therefore, analyze both conducting and non- conducting material without the need for a conductive coat and/or other charge balancing techniques. The high sensitivity of LA-ICP-MS allows small samples to be

quantified, which is ideal for spatial resolution that can be used to investigate

compositional gradients across a sample. Finally, trace-element analysis using LA-ICP-

MS does not require complicated interference corrections inherent in other analytical

techniques, in essence analysis and the hardware is considerably cheaper among

different manufacturers such as Jordan valley Inc. Furthermore, LA-ICP-MS does offer a

cheaper alternative for trace element analyses with minimal destruction making it ideal 217

for archaeological investigations where materials are precious. Another advantage of

LA-ICP-MS is that it is easy to identify and analyze the presence of any mineral inclusions. Analyses that have ablated into invisible sub-surface micro-phenocryst

phases (such as feldspar, zircon or apatite) in obsidian can be easily recognized because

of anomalous concentrations of Sr, and Zr. Such anomalous concentrations give

misleading results. These analyses can be removed from the data sets so that only the

glassy component of the obsidian is considered in the comparisons. Given this proviso, it

has been found that a larger number of elements can accurately be quantified by LA-

ICP-MS, provided well characterized standards are available (Denoyer, 1991). Despite all

the above advantages LA-ICP-MS is discredited for being minimally destructive. “Carter

pit” in the order of tens of microns are made on the sample. It should however be noted

that the Carter pits are very insignificant and does not have structural effect or destroy archaeological specimens. Further more the Carter pits can be controlled by adjusting

the laser intensity to achieve minimal Carter pits in the order of 1-5 microns (Gratuze

1999; Bugoi et al. 2004). Another draw back is that using LA-ICP-MS include multi-

charged species mainly Ba++ whose remains need to be corrected. Calibration

procedures are still a problem for effective utilization of the technique, as there are very

few solid reference materials that can be used to calibrate the method solid standard

with overall composition.

Due to the almost non-destructive nature, LA-ICP-MS, this technique has proved

to be a powerful tool for determination of trace elements, and therefore very useful in

characterizing and determining the provenance of obsidian fragments of archeological 218 interest (Carter et al. 2006; Gratuze 1999; Bugoi et al. 2004) especially for a region such as Koobi Fora where baseline reference data were still lacking.

219

Figure 7.3: LA-ICP-SM instrumentation setup

220

For this project, all the samples were analyzed whole by Laser Ablation LAICP-MS at the Department of Geological and Planetary Sciences University of Cape Town. It should however be noted that not all samples were analyzed using ICP-MS, some were analyzed using XRF. But all the samples analyzed using ICP-MS were also analyzed using

XRF in order to determine the comparability of the data. The analysis of each sample required minimal preparation. Samples were cleaned with a piece of cotton soaked in methanol before being placed directly into the ablation chamber of the Laser Ablation

System. The analysis involved, each flake of obsidian having five separate spectra acquired from it for 40 separate elements. Spectra are acquired by burning a small volume of material from the sample (‘ablating’) using a high-intensity ultraviolet pulsed laser beam and analyzing the vaporized material in the ICP-MS. The ICP-MS system that

was used for project was an Agilent 7500a quadruple instrument coupled to a Nd:YAG

New Wave UP 213 laser. At the beginning of each day the ICP-MS was optimized for

sensitivity during line scans that rastered across a polished NIST 612 glass standard. The

production of both ionized oxides and doubly charged ions was also monitored and

lowered to 0.5%. Helium was then transported to the laser ablation cell (~0.85 L/min)

and was mixed with argon gas (1.02 L/min) before entering the ICP-MS. Data were

collected in a time-resolve mode for 90 seconds, which included 30 seconds of

background signal, 30 seconds for sample signal (dwell time), and washout time (30 s).

Each spot was pre-ablated for 5 seconds to remove surface contaminants. Laser

parameters were set to 80% power, 10 Hz, and 80 mm diameter spot size (Pickering et

al. 2004). Three different transects were analyzed on each standard and obsidian 221 sample. Twenty-eight different elements were measured. The National Institute of

Standards and Technology (NIST) and the United States Geological Survey (USGS) glass

(SRM 610 and 612) served as a calibration standard and were analyzed three times at the beginning and end of each sample slide and after every 4 to 6 obsidian samples. To assess LA-ICP-MS performance, one of the Northern Island source samples was analyzed daily and showed excellent precision from day to day. Moreover, the USGS obsidian standard (RGM-1) was analyzed each day and showed good agreement with the accepted concentrations, ranging between 2and 5% relative standard deviation (RSD) for most elements.

The raw data were reduced using GLITTER, the GEMOC Laser ICP-MS Total Trace

Element Reduction software package. To produce quantitative trace-element analyses,

LA-ICP-MS requires the knowledge of at least one element in the unknown to act as an internal standard (usually SiO2 in rhyolitic materials). As no concentrations were known for any elements in the obsidian flakes analyzed, a value of 69.895% was assumed for

SiO2 (the same concentration as in the NIST SRM 610 reference material) to act as the internal standard, and to give approximate concentrations. Concentrations were calculated based on the known concentration of an internal standard, which is slightly different for each sample. However, the internal standard was not previously measured for the unknown obsidian flakes, so elemental ratios were utilized instead, which eliminated the internal standard in the calculations, and proved to be useful in source discrimination. Because of this estimate of the internal standard, the reported concentrations cannot be used directly for comparison (as they are calculated using this 222

assumed value of the internal standard, and not the true concentration). Ratios of one

element to another (e.g. Zr/ Y, Zr/Nb or any other element pair), however, are correct

(as the ratios are independent of the actual concentration), and these can be used in

identifying groups within the data. Similarly triangular discrimination diagrams plot the

relative proportions of three elements, and can also be used in provenance/correlation

studies. To avoid any possible confusion, here only plots of the data are presented, the

approximate concentration data from which they are derived is not presented, but

would be reported in the appendix section. LA-ICP-MS was chosen for this analysis

because it offers a myriad of advantages over other methods. One advantage over solution analytical methods in that it is easy to identify in the analysis the presence of any mineral inclusions. Analyses that have ablated into invisible sub-surface micro-

phenocryst phases (such as feldspar, zircon or apatite) in the obsidian can be easily recognized because of anomalous concentrations of Sr, Zr and rare earth elements

These analyses can be removed from the data sets so that only the glassy component of the obsidian is considered in the comparisons. The achievements of reliable results by

LA-ICP-MS are depended on two fundamentals, namely the representative generation of ions and the quantification step.

The attribution of artifacts to sources was performed by selecting the elements or element ratios that better discriminate between sources (Carter et al. 2008; Eerkens et al. 2008; Gratuze 1999). Although some ratios (e.g. Zr/Y and Zr/Nb) and some elements (Ba among other rare earth elements, La, Ho, Yb, Dy, Gd) are commonly used, several authors (Eerkens et al. 2008; Carter et al. 2008; Gratuze 1999) demonstrated 223

that different elements or element ratios may be used for sourcing archaeological

objects. Others (Carballo et al. 2007; Pereira et al. 2003) used Principal Component

Analysis (PCA) for source attribution with similar results. It should however be noted

that when the existing dataset in large enough clear identification can be achieved. The

existing dataset on obsidian chemical composition is large enough to enable the clear

identification of the discriminating elements and/or ratios. Consequently, the

forthcoming research on obsidian sourcing can only focus on the determination of these

elements.

The disadvantages of LA-ICP-MS have already been highlighted above. I would

like to wrap-up by highlighting the advantages of these methods that are specific to

obsidian sourcing and characterization and my reasons for coupling these techniques.

LA-ICP-MS detection seems to be a perfect tool for obsidian characterization. It shows four major advantages over other techniques such as XRF, PIXE and INAA, enabling the direct analysis of obsidian objects. Firstly, LA–ICP–MS shows much lower limits of

detection (Gratuze 1999). This feature enables the determination of elements

impossible to measure with other techniques (mainly Rare Earth Elements by XRF and

Particle Induced X-ray Emission (PIXE). This provides complete characterization and

source assignments (Bugoi et al. 2004). Secondly, the possibility to introduce several

samples in one sample cell reduces the attended operations cost. Thirdly, small,

millimetric samples can be investigated: a sample with a surface as small as one square

millimeter can be easily analyzed. Finally, the cost and accessibility of the

instrumentation are in favor of laser ablation LA–ICP–MS. The micro-destructive nature 224

of this sampling technique is the only drawback, which could hinder its application when

analyzing fragile objects.

Coupling of these methods was ideal because it allowed for a complete characterization

of obsidian as trace elements are determined by ED-XRF and high field strength

elements and Rare Earth Elements (REE) are analyzed by LA-ICP-MS. These elements

(Rb, Sr, Y and Zr) are the most sensitive indicators for discriminating obsidian sources as

they are unique to each lava flow, and can therefore be used as source identifiers with

enough accuracy and sensitivity to allow confident provenance conclusions (Carter et al.

2006; Bugoi 2004; Shackley 2005).

7.6 Results from Geochemical Characterization

The stone artifacts assemblage from the Galana Boi deposits mainly obsidian

artifacts represent human subsistence and mobility patterns in diverse settings. New

excavations and extensive raw material sourcing allow the technology of the mid

Holocene population to be viewed in a manner which may reflect the uses and climatic

pressures acting on tool mediated behaviors. This section will present findings, and

explore the possible explanations variation in the obsidian use in Lake Turkana Basin.

In the beginning of this project, obsidian artifacts were initially examined in the

field to determine if visual characteristics could be used to identify categories of visual

types to be potentially correlated with geochemical sources. Two main visual types were

identified: the first was translucent obsidian that appeared black in reflected light and 225

green in diffused light. This visual type represented approximately 59% of all obsidian

recovered at the sites under investigation. The second visual type was opaque obsidian

that appeared black in reflected light and “root beer” in diffused light, but this root beer

color was only visible along the thinnest margins. The material was almost entirely

opaque. This visual type represented approximately 28% of all obsidian recovered at the study sites. The remaining obsidian artifacts (12%) were not able to be easily assigned to either visual type. There was no correlation between visual type and geochemical groups. Visual examination, this is not a reliable method for assigning artifacts to geochemical sources.

A series of three, 4 week field seasons was conducted in Lake Turkana Basin resulted in a geological rock sample database from four obsidian outcrops. A total of 60 geological reference samples were collected following the protocol outlined above.

Because of the rough terrain in Lake Turkana Basin, the number of samples varied from source to source. Surgei geological outcrop was repeatedly sampled in an attempt to capture any form of intra-source variation in geochemistry of obsidian rock types in our collection area. Detailed methodological and instrumentation information on X-ray florescence have already been discussed at length in the preceding section.

Samples are attributed to source groups via trace elements and Rare Earth

Elements (REE) chemistry was utilized to link artifacts to geographically isolated source groups. Prior to running the discriminant function analysis, both ED-XRF and LA-ICP-MS

data were log10 transformed (Glasscock 1998). This transformation of data was

necessary for two important reasons. First, transformation is necessary with ED-XRF 226 data due to concerns over chemical concentrations that vary by orders of magnitude; some chemical concentrations (major elements) are on the order of 10 times larger than others (trace elements) (Baxter 1994). A logarithmic transformation was used to normalize the data set and eliminate the discrepancies in orders of magnitude, with the result that all elements concentrations are given equal weight in the analysis. This is important because it is often the presence of trace elements that define a specific provenance. Second, transformation was necessary because both discriminant function analysis and two dimensional scatter plots assume normal distribution of the data.

These statistical techniques will produce spurious results when applied to non- normalized raw data. Trace elemental analyses will use a method of elemental bivariate plots. Previous provenance studies have suggested that samples that fall within a three standard deviation or 95% confidence ellipse of the variation of a known rock group (i.e. geological reference source) is an accurate measure of geochemical group inclusion

(Malyk-Selivanova et al. 1998). However, multivariate techniques are not the best for the final analysis of group distinctions because they may simplify more complex geochemical relationships and will be affected by the collinearity of elemental signatures as those associated with reheating and cooling of lava in the magma chambers. The process of fractional crystallization and magma mixing during the emplacement of igneous bodies of rock usually results in large masses that are relatively homogenous. While this is useful because it allows the geochemical distinction of a specific rock group, this rock group can have a very wide geographical expanse and can have very varied (albeit delimited) chemical composition. During the cooling process of 227

igneous masses certain elements will be incorporated into the formation of phenocrysts

rapidly. These are considered the compatible elements. Other elements will be

preferentially concentrated in the liquid phase during the melting and crystallization.

These elements are termed the “incompatible” elements and often they are found in

trace levels (less than a few thousand parts per million) in many igneous rocks. These

elements are found in specific concentrations based on the exact nature of the cooling

rate and the pressure that the rock underwent during emplacement of the rock so they

can be used to characterize the specific rock sources. In this sense these trace elements

can be used to show intra source variation. Hence, this study used ratios of specific

trace elements to try and characterize specific rock groups.

7.7 Results from ED-XRF analysis

Ten elements were measured using the above methodology and are presented here as parts per million (ppm) values, (Ti, Mn, Fe, Zn, Rb, Sr, Y, Zr, Nb and, Ba). A detailed breakdown of elemental composition of artifacts from each of the archaeological site and the geological reference materials is presented in Table 7.2 and plotted in Figures 7.4 and 7.5. Based on the fact that the sources do not significantly overlap (95% confidence intervals) assume that the four geochemically distinct groups represent different geographical distinctions. The assignment to source was made by comparison with the compositional groups defined by trace elements using two- dimensional plotting and multivariate (Figure 7.9) analysis. Geological reference 228 samples correlate with names indicated in Figure 7.1 and Table 7.1. The results obtained, show a high degree of comparability between the values obtained here and accepted values for Standard reference RGM-1 elemental concentrations. At least five distinct chemical types of obsidian can be provisionally recognized among the sampled archaeological specimens from the five sites that were studied (Figure 7.6). For convenience of reference, these archaeological groups have been designated as Lake

Turkana Basin (LTB) groups 1-5 and only when a geological reference samples matches

(within 95% confident eclipse) of the geographic source, is when a geographic name was added as an identifier. Three of the archaeological obsidian types, including the one most commonly used group (group 3) are known from artifacts only. Overall, 60% of the analyzed archaeological obsidian was matched to known sources while 40% remained unmatched.

However at present all the four sources were used for artifact manufacture or raw material sourcing (Figure 7.7a-e). The most geological source, Suguta and Surgei is a well-defined compositional type that is found in archeological sites. The distribution extends at all the sites from Koobi Fora to Ileret. Not only is the Suguta the principal obsidian type (75%) at the GaJi 4 site, but it is also the dominant type for archaeological materials at FwJj 5 and FwJj 27. It is also present at FwJj 25W and FwJj 25.

Suguta (UTM, 37N, E: 223777, N 239709) is an arid part of the Great Rift Valley in

Kenya, directly south of Lake Turkana (Figure 7.1). Obsidian source at Suguta lies at the northern end of the valley, where it is separated from Lake Turkana by a complex series of volcanoes ridges called the “Barrier” separating the southern end of Lake Turkana 229

Basin and the Suguta Basin. It is from this ‘barrier” that the geological reference samples herein referred to as Suguta source was collected through a collaborative effort. The

Suguta was definitely hydrologically isolated from the Turkana Basin during the

Holocene (Garcin et al. 2009). The volcanic here is of Obsidian from this source is of high quality and it is the dominant type in at our entire archaeological site. It appears that

Suguta and Surgei are the dominant or exclusive type present in all archeological sites that were investigated.

The second most widely distributed obsidian type, LTB-1, was recognized among archaeological artifacts at all five sites. In more southerly sites it was found at the excavated archaeological horizons B at GaJi 4. The source of this material is unknown, although the geographic distribution may provisionally suggest north of Turkana area source.

There is a strong similarity between LTB-1 and LTB-2 type and the volcanic edifice of Shin (37N 220914, E485520) located along the volcanic margin of the Lake

Turkana sedimentary Basin. Shin source is composed of unmodified pebbles occurrences that are rhyolitic and are about 13.1 Ma old (McDougall and Watkins, 1988). These sources are so small that at distances of 20 meters away from the outcrop, secondary sources (clastic sediments and cobbles) are very infrequent. At distances of 1 km or more obsidian is completely absent from modern day drainages. This suggests that if these sources were used by prehistoric peoples, they were procured directly from the outcrop and not obtained from secondary sources (i.e. conglomeratic facies). However, 230 the obsidian sampled from the Shin localities are generally of poor quality and are unlikely to have been used frequently as raw material for making stone tools.

Compositionally the obsidians from Shin are similar to those at GaJi 4, FwJj 25 and FwJj 25W. The principal differences in composition are that the obsidians from Shin are lower in Zirconium (Zr) and Yitrium (Y) values. Research investigating the chemical heterogeneity of obsidian sources has revealed that individual flows within peralkaline chill zones (as is the case at this study area) sometimes possess trace element chemical differentiations vast enough to warrant false assignment to distant sources (Hughes

1994; Hughes and Smith 1993; Shackley 2005; Tykot 1998).The differences in lower amounts of Zr and Y, could be as a result of reheating and cooling in the magma chamber. Even if multivariate analysis for elements from these sources were remarkably good, (Figure 7.9) it would be worth collecting and analyzing additional samples at this source. In particular, the interiors of larger fragments of these potential source obsidians would be of interest because they may be less hydrated than the outer surfaces. Thus the differences may be due to hydration of the geological reference obsidians from Shin. For other elements the correspondence is remarkably good, so that it would be worth collecting and analyzing additional samples from these Miocene flows. In particular, the interiors of larger fragments of this source obsidian would be of interest because they may be less hydrated than the outer surfaces. Based on this geologic sampling and analysis of obsidian sources, the source is extremely uniform in the concentrations of elements used to discriminate between sources especially Shin and North Island. Any errors in the assignment of archaeological obsidian artifacts to 231

source therefore are likely the result of operator error and errors in interpreting trace

element concentrations, rather than due to variations in the geochemical composition

North Island and Shin.

Four other compositional types of obsidian are also known now among artifacts from this region. Their appearance at archaeological sites is summarized in Figure 7.7a- e. These less common types tend to be high in number at FwJj 25W. For example site

FwJj 25 and 25W has four possible groups (LTB 1, 2,3 and 4), GaJi 4 site has two (LTB 1 and 2).

The Surgei obsidian sources (UTM coordinates 37N 223478, E485868 and 37N

212660, E484106; WGS 84 datum) are located along the northeast edge of the Surgei-

Asille Plateau within the tuffs of the Langaria Formation (Braun 2006; Watkins 1983).

Merrick and Brown (1984) previously suggested that the Surgei area might been a major source area, and my analysis of 15 geological reference samples (Table 7.2) reveals that at least each of the archaeological sites has samples similar to those from Surgei source

(Figure 7.7 a-e). Due to the large geographical extent of the Surgei outcrop the present geochemical characterization may be deflating multiple sources into one characterization. Clearly further characterization of this source is needed, but the Surgei area is apparently among the major source of obsidian for artifact manufacture as had been previously suggested (Merrick and Brown 1984).

Another compositional group that was recognized in this study is matched to those from North Island. North Island (37N 172080, E449563) is 25 km from the eastern shore of Lake Turkana and 18 km from the western shore. The Island is a caldera 232

complex characterized by cinder cones and Carters, as well as abundant obsidian flows

along the badland eroded areas. The areas where the obsidian flows are known have no

evidence of archaeological sites. The height of these sources relative to past high lake

level stands precludes the possibility that these sources were inaccessible during the

major high lake stands during the Holocene. Moreover, ancient lake levels indicate that

the lowest level the lake ever dropped was 376 masl (Butzer 1980; Harvey and Grove

1982; Owen et al. 1982). Thus, even at the lowest lake levels during the Holocene period

North Island was never accessible by a terrestrial bridge. The determination that 8% of the archaeological specimens are geochemically similar to the obsidian source on North

Island raises important anthropological questions about the nature of obsidian transport among groups of people during the Holocene in the Turkana basin. In particular, all of the artifacts from Gaji 4, FwJj 25 , FwJj 5 and FwJj 27 are geochemically similar to obsidian outcrops from North Island.

When the chemical composition of archaeological obsidian from FwJj 25W was plotted against the stratigraphic distribution it was found that there was no correlation with the levels. All the known groups were equally distributed along the stratigraphy

Horizon at site FwJj 25W (Figure 7.10). This was interpreted to mean that all sources were exploited simultaneously at all time again pointing at high residential mobility or contacts with the southern sources and other yet to be found sources were represented. There was no preference to levels; all the levels had mixed sources meaning that they were all utilized. East of those levels also showed evidence of the unknown sources 233

Obvious traces of quarrying and flaking debris associated with mining and related prehistoric activities at all our geological sources were rare and may have been obscured by various factors (Merrick and Brown 1984; Merrick et al. 1994; Ndiema personal observation). Evidence of quarrying at Surgei may have been obscured for multiple reasons. Outcrops of obsidian are relatively inconspicuous and numerous livestock tracks in the region may have obscured evidence of this activity. In addition this region is currently exposed to intense erosion during seasonal rains which may have removed quarry debris and/or rapidly buried other evidence of quarrying behaviors.

On current physical and chemical evidence, it appears that all six of the obsidian types identified within the research area are likely to be from Turkana area and other unaccounted for sources. The remaining unassigned source(s) of obsidian is not certainly known, but a strong case may be made for South western Ethiopia and

Southern Sudan. In addition to the small artifact size and occasional appearance of cortex on the obsidian suggesting manufacture utilizing small pebbles, there appear to be no close chemical matches with any of the more northerly Ethiopian Rift sources currently known (Negash and Shackley 2006; Negash et al. 2007; Negash et al. 2006), and none with the somewhat better documented central Kenyan sources (Merrick and

Brown 1984; Merrick et al. 1994).

234 Table 7.2: Elemental composition of geological reference samples from the sampled sources

Location Sample # Mn Fe Zn Rb Sr Y Zr Nb Ba North Island NI 4 6603.9 138460.2 287.5 122.5 26.0 158.5 1246.3 137.1 63.7 North Island NI 2 298.8 28474.2 196.8 124.5 14.8 113.6 757.9 141.6 42.4 North Island NI 7 688.4 31672.0 287.7 153.5 22.3 138.4 729.6 155.7 62.1 North Island NI 6 890.1 39405.0 136.4 131.6 84.5 86.1 1091 130.3 725.6 North Island NI 3 948.3 43612.3 143.9 123.9 102.0 82.9 757.3 134.4 905.0 North Island NI 5 7285.2 39614.6 299.8 146.1 37.0 136.4 757.9 154.8 186.4 North Island NI 1 894.0 41929.6 138.7 114.9 155.0 81.2 677.7 120.7 810.2 North Island NI 9 945.0 42802.7 237.1 147.2 36.5 101.5 584 116.7 724.2 RGM‐1 Standard 277.593 13549.04 24.239 147.811 104.94 27.927 212.738 6.022 1111.4 Shin SH 1 1188.9 35976.8 183.0 120.4 43.7 81.2 759.6 176.6 754.2 Shin SH 2 1181.4 43922.0 201.7 133.4 39.9 78.7 830.4 187.0 1120.4 Shin SH3 1128.9 3576.8 193.0 114.4 46.8 71.2 769.6 196.0 1254.3 RGM‐1 Standard 296.212 13549.12 21.936 148.32 103.271 26.95 211.08 7.637 1486.6 Suguta Valley SV 01 806.8 30209.1 174.3 121.8 5.4 78.1 660.0 94.0 846.4 Suguta Valley SV 02 880.9 28744.3 170.0 118.9 4.5 75.7 600.0 91.8 527.2 Suguta Valley SV 03 880.1 29931.0 173.5 113.4 3.5 83.9 576.8 89.4 ‐4.3 Suguta Valley SV 04 730.1 26069.5 156.0 102.6 3.2 70.1 563.5 83.2 53.9 Suguta Valley SV 05 918.7 35249.5 204.1 118.5 2.4 77.2 545.9 90.6 30.3 Suguta Valley SV 06 857.4 34578.5 193.8 123.9 2.5 82.5 630.9 96.2 18.4 Suguta Valley SV 07 849.6 33845.6 198.1 130.7 2.1 87.2 700.3 100.9 25.4 Suguta Valley SV 08 949.0 27641.9 166.9 105.6 4.3 70.1 610.0 86.7 63.9 Suguta Valley SV 09 866.7 30244.4 173.3 105.1 5.7 69.3 619.4 86.6 102.7 Suguta Valley SV 10 934.7 33059.2 199.0 123.5 2.5 83.8 605.9 99.7 106.0 Suguta Valley SV 11 883.0 32710.6 194.4 125.0 2.5 77.5 617.3 97.2 579.9 Suguta Valley SV 12 1053.8 36291.8 219.3 142.6 2.6 89.1 603.0 100.1 49.9 Suguta Valley SV 13 802.3 31698.6 208.1 115.0 5.4 82.4 681.6 89.6 959.0 Suguta Valley SV 14 609.4 30523.8 167.8 108.8 3.5 73.2 582.5 91.5 160.7

235

Suguta Valley SV 15 596.2 27208.9 160.6 111.8 7.2 73.3 629.0 88.9 558.2 Suguta Valley SV 16 847.4 33354.4 190.5 128.5 3.6 81.9 625.7 100.6 624.5 Suguta Valley SV 17 805.9 31344.3 168.7 114.4 3.5 77.7 612.9 91.5 690.7 Suguta Valley SV 18 1117.0 34559.4 187.0 116.5 4.7 80.2 689.1 107.2 757.0 Suguta Valley SV 19 927.0 30012.1 160.2 113.6 5.2 76.6 633.3 90.9 577.8 Suguta Valley SV 20 1020.2 33967.5 208.6 118.8 2.1 81.4 654.1 97.3 602.6 RGM‐1 Standard 271.818 13607.15 23.34 150.433 103.937 22.38 208.367 8.457 627.5

Surgei SRG 10 990.3 40201.4 144.6 139.6 89.4 88.0 805.4 142.5 627.5 Surgei SRG 15 900.8 40056.2 143.8 135.3 89.7 87.7 764.2 132.0 652.3 Surgei SRG 14 2397.8 46267.4 261.7 138.6 34.6 137.4 1324.5 156.2 677.2 Surgei SRG 3 868.2 69066.8 262.2 126.7 24.7 142.0 1171.2 150.3 702.1 Surgei SRG 12 609.5 31198.8 263.5 169.2 21.6 137.8 1246.3 164.4 726.9 Surgei SRG 8 535.7 33922.2 279.9 134.4 19.6 129.7 1219.5 151.4 751.8 Surgei SRG 13 602.1 38952.3 289.1 156.0 16.4 129.3 1303.8 163.1 776.6 Surgei SRG 5 611.5 33582.6 289.8 163.9 20.3 138.5 1285.3 154.3 801.5 Surgei SRG 2 856.2 26745.3 203.1 119.1 14.6 111.5 1090.5 146.4 826.3 Surgei SRG 9 550.7 29573.5 249.2 139.9 32.3 130.7 1199.6 153.5 851.2 Surgei SRG 11 683.7 31229.6 263.8 165.1 32.1 131.7 1240.8 154.8 876.1 Surgei SRG 6 905.0 39693.4 153.1 131.7 77.7 86.4 757.3 132.0 900.9 Surgei SRG 16 577.0 31287.2 255.7 146.9 15.9 132.3 1246.3 163.4 925.8 Surgei SRG 7 1111.6 47677.2 172.4 148.3 80.6 94.3 808.9 146.0 950.6 Surgei SRG 4 616.5 29200.7 207.2 104.6 21.9 101.2 795.9 102.9 975.5 Surgei SRG 39 922.9 31256.9 201.5 116.1 11.1 80.3 657.0 96.4 1000.3 Surgei SRG 41 657.6 30517.7 262.4 163.8 44.7 121.9 1188.2 149.6 1025.2 Surgei SRG 42 561.1 25406.0 214.4 132.3 37.3 106.9 1080.4 134.8 1050.1 Surgei SRG 43 576.7 28530.5 248.4 130.7 38.0 138.1 1179.5 147.8 1074.9 RGM‐1 Standard 296.212 13549.12 21.936 148.32 103.271 26.95 211.08 7.637 1099.8

236

Figure 7.4: Bivariate plot for Zirconium, Niobium and Yttrium ratios show different sources areas.

237

Figure 7.5: Bivariate plot for Zirconium and Niobium show different obsidian sources areas.

238

Figure 7.6: Elemental Composition archaeological artifacts showing at least 5 compositional groups

500 95% Conﬁdence eclipse 450 LTB 5 400 LTB 4

350 FwJj 27 300 FwJj 5 250 LTB 3 GaJi 4

Niobium (ppm) 200 FwJj 25 150 LTB 1 LTB 2 FwJj 25W 100

0 0 500 1000 1500 2000 2500 3000 3500 4000 Zirconium (ppm)

239

Figure 7.7a: Bivariate plots of Zirconium, Niobium and Yttrium ratio show Suguta valley being the main source

FwJj 27 95% conﬁdence eclipse 9.00

8.00

7.00 FwJj27

6.00 Suguta Valley North Island Zr/Nb (ppm) Shin 5.00 Suregei

4.00

3.00 3.00 5.00 7.00 9.00 11.00 13.00 15.00 17.00 Zr/Y (ppm)

240

Figure 7.7b: ED-XRF, Zr/Y and Zr/Nb two dimensional plots for FwJj 5 artifacts and geological sources. Where as Suguta Valley seems to be the main there are source unknown

FwJj 5 95% conﬁdence Eclipse

10.00

9.00

8.00

7.00

6.00 FwJj 5 (stone Bwol Site) 5.00 Suguta Valley

Zr/Nb (ppm) 4.00 North Island 3.00 Shin 2.00 Suregei 1.00

0.00 0.00 5.00 10.00 15.00 20.00

Zr/Y (ppm)

241

Figure 7.7c: ED-XRF two dimensional plots for Zr/Yttrium and Zr/Nb ratios at Gaji 4. The diversity of sources is evident including some yet to be found sources

9.00 GaJi 4 95% conﬁdence eclipse

8.00

7.00

GaJi 4

6.00 Suguta Valley

Zr/Nb (ppm) North Island

5.00 Shin

Suregei

4.00

3.00 0.50 2.50 4.50 6.50 8.50 10.50 12.50 14.50 16.50 Zr/Y (ppm)

242

Figure 7.7d: ED-XRF two dimensional plots of Zr/Y and Zr/Nb ratios at FwJj 25The diversity of sources including North Island is evident

12.00 FwJj 25 95% conﬁdence eclipse

10.00

8.00

FwJj 25 Suguta Valley 6.00 North island Zr/Nb (ppm) Shin 4.00 Suregei

2.00

0.00 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 Zr/Y (ppm)

243 Table 7.3: Elemental composition of archaeological samples from studied sites

Source/ Site Cat # Artifacts Ba Ho Zr Yb La Nb Y Zr/Nb Zr/Y FwJj 27 29 Artifact 68.48 2.75 625.55 8.01 73.20 90.64 76.05 6.90 8.23 FwJj 27 75 Artifact 80.40 2.94 656.63 8.42 77.81 95.88 78.40 6.85 8.38 FwJj 27 75 Artifact 78.64 2.98 672.39 8.63 80.16 97.43 79.86 6.90 8.42 RGM1‐S4 Standard 37.279 146.908 104.093 24.376 224.873 10.008 805.543 26.511 20.065 FwJj 5 107 Artifact 77.83 3.17 692.38 9.12 84.16 99.76 83.64 6.94 8.28 FwJj 5 71 Artifact 82.77 3.18 716.13 9.25 86.23 103.32 82.14 6.93 8.72 FwJj 5 87 Artifact 80.11 3.15 676.58 9.37 82.38 97.86 80.88 6.91 8.37 FwJj 5 59 Artifact 81.77 3.10 682.45 9.40 82.56 98.25 82.03 6.95 8.32 FwJj 5 82 Artifact 79.70 3.24 712.33 9.46 86.71 102.11 85.72 6.98 8.31 FwJj 5 57 Artifact 78.12 3.18 693.75 9.52 84.25 97.51 84.91 7.11 8.17 FwJj 5 45 Artifact 77.85 3.36 715.56 9.57 86.96 99.25 87.14 7.21 8.21 FwJj 5 89 Artifact 77.34 3.14 674.04 9.61 82.50 95.54 81.86 7.06 8.23 FwJj 5 61 Artifact 79.53 3.43 736.87 9.65 89.01 102.04 89.88 7.22 8.20 FwJj 5 88 Artifact 80.06 3.28 685.39 9.75 85.58 96.44 84.21 7.11 8.14 FwJj 5 109 Artifact 61.16 3.41 793.81 9.85 100.18 130.25 91.00 6.09 8.72 FwJj 5 46 Artifact 79.90 3.38 734.90 9.89 88.55 101.64 89.62 7.23 8.20 FwJj 5 78 Artifact 84.19 3.38 734.26 9.92 90.68 105.44 89.08 6.96 8.24 FwJj 5 44 Artifact 82.57 3.38 739.08 9.93 88.88 103.16 89.10 7.16 8.29 FwJj 5 64 Artifact 87.29 3.39 733.80 9.95 88.94 103.30 88.99 7.10 8.25 FwJj 5 51 Artifact 97.73 3.39 731.95 9.95 87.44 103.38 86.93 7.08 8.42 FwJj 5 40 Artifact 56.20 3.39 704.56 9.15 75.40 84.60 625.31 8.33 1.13 FwJj 5 32 Artifact 68.46 3.45 705.05 9.18 80.46 85.87 705.05 8.21 1.00 FwJj 5 25 Artifact 59.78 3.24 609.60 8.57 69.41 75.51 609.60 8.07 1.00 FwJj 5 18 Artifact 59.79 3.54 643.33 9.00 70.75 80.46 643.33 8.00 1.00 RGM1‐S4 Standard 37.279 146.908 104.093 24.376 224.873 10.008 805.543 26.511 20.065

244

GaJi 4 32 Artifact 90.02 3.36 731.86 10.04 91.14 104.82 89.12 6.98 8.21 GaJi 4 111 Artifact 56.99 3.48 819.17 10.04 104.19 137.88 92.84 5.94 8.82 GaJi 4 41 Artifact 85.95 3.44 748.69 10.07 92.03 105.72 91.42 7.08 8.19 GaJi 4 113 Artifact 55.95 3.49 825.51 10.08 105.19 139.78 93.30 5.91 8.85 GaJi 4 60 Artifact 30.19 3.35 739.40 10.09 89.55 116.59 91.16 6.34 8.11 GaJi 4 115 Artifact 55.69 3.50 827.10 10.09 105.44 140.26 93.42 5.90 8.85 GaJi 4 117 Artifact 55.62 3.50 827.49 10.10 105.50 140.38 93.44 5.89 8.86 GaJi 4 119 Artifact 55.61 3.50 827.59 10.10 105.52 140.41 93.45 5.89 8.86 GaJi 4 120 Artifact 55.59 3.50 827.67 10.10 105.53 140.43 93.46 5.89 8.86 GaJi 4 118 Artifact 55.59 3.50 827.69 10.10 105.54 140.44 93.46 5.89 8.86 GaJi 4 116 Artifact 55.56 3.50 827.89 10.10 105.57 140.50 93.47 5.89 8.86 GaJi 4 114 Artifact 55.43 3.50 828.68 10.10 105.69 140.74 93.53 5.89 8.86 GaJi 4 112 Artifact 54.91 3.51 831.85 10.13 106.19 141.69 93.76 5.87 8.87 GaJi 4 76 Artifact 28.10 3.48 759.53 10.13 90.36 118.47 93.16 6.41 8.15 GaJi 4 58 Artifact 137.25 3.45 786.76 10.19 142.06 123.68 83.07 6.36 9.47 GaJi 4 43 Artifact 86.86 3.53 762.17 10.21 93.00 106.34 92.30 7.17 8.26 GaJi 4 110 Artifact 52.82 3.54 844.53 10.22 108.20 145.50 94.68 5.80 8.92 GaJi 4 42 Artifact 83.49 3.61 758.67 10.45 93.05 105.39 93.21 7.20 8.14 GaJi 4 108 Artifact 44.48 3.66 895.25 10.59 116.21 160.75 98.36 5.57 9.10 GaJi 4 35 Artifact 92.22 3.67 790.54 10.65 97.94 111.89 95.51 7.07 8.28 GaJi 4 37 Artifact 90.48 3.77 803.46 10.99 97.95 112.31 97.16 7.15 8.27 GaJi 4 38 Artifact 66.36 3.77 672.55 8.98 73.67 80.25 672.55 8.38 1.00 GaJi 4 39 Artifact 81.41 3.45 691.50 9.30 77.89 83.69 691.50 8.26 1.00 GaJi 4 46 Artifact 70.49 3.54 705.80 9.56 80.48 86.29 705.80 8.18 1.00 RGM1‐S4 Standard 37.279 146.908 104.093 24.376 224.873 10.008 805.543 26.511 20.065 FwJj 25 91 Artifact 13.75 3.85 1042.37 11.10 141.24 209.62 105.03 4.97 9.92 FwJj 25 30 Artifact 9.09 3.89 1027.85 11.20 140.81 208.90 105.23 4.92 9.77 FwJj 25 93 Artifact 11.79 4.08 1084.18 11.81 146.50 218.71 111.08 4.96 9.76 FwJj 25 96 Artifact 11.30 4.14 1094.63 11.99 147.82 220.99 112.59 4.95 9.72

245 FwJj 25 98 Artifact 11.18 4.16 1097.24 12.04 148.15 221.55 112.97 4.95 9.71 FwJj 25 100 Artifact 11.15 4.16 1097.90 12.05 148.23 221.70 113.06 4.95 9.71 FwJj 25 102 Artifact 11.14 4.16 1098.06 12.05 148.25 221.73 113.08 4.95 9.71 FwJj 25 104 Artifact 11.14 4.16 1098.10 12.05 148.25 221.74 113.09 4.95 9.71 FwJj 25 105 Artifact 11.14 4.16 1098.12 12.05 148.26 221.74 113.09 4.95 9.71 FwJj 25 106 Artifact 11.14 4.16 1098.12 12.05 148.26 221.74 113.09 4.95 9.71 FwJj 25 103 Artifact 11.14 4.16 1098.14 12.05 148.26 221.75 113.10 4.95 9.71 FwJj 25 101 Artifact 11.13 4.16 1098.22 12.05 148.27 221.77 113.11 4.95 9.71 FwJj 25 99 Artifact 11.12 4.16 1098.55 12.06 148.31 221.84 113.15 4.95 9.71 FwJj 25 97 Artifact 11.06 4.17 1099.86 12.08 148.48 222.12 113.34 4.95 9.70 FwJj 25 95 Artifact 10.81 4.20 1105.08 12.17 149.13 223.26 114.10 4.95 9.69 FwJj 25 19 Artifact 8.42 4.06 1277.59 12.34 135.90 214.93 115.91 5.94 11.02 FwJj 25 92 Artifact 9.84 4.32 1125.99 12.53 151.77 227.81 117.13 4.94 9.61 FwJj 25 36 Artifact 37.22 4.43 911.20 12.71 114.26 138.62 114.37 6.57 7.97 FwJj 25 3 Artifact 3.47 4.42 1388.21 13.29 157.65 228.82 125.83 6.07 11.03 FwJj 25 85 Artifact 2.92 4.54 1260.22 13.54 145.78 206.71 116.96 6.10 10.78 FwJj 25 90 Artifact 5.92 4.78 1209.61 13.97 162.29 246.00 129.23 4.92 9.36 FwJj 25 74 Artifact 12.00 4.69 1469.20 14.27 159.94 243.66 129.82 6.03 11.32 FwJj 25 4 Artifact 9.88 4.94 1501.00 14.95 169.66 247.72 135.57 6.06 11.07 FwJj 25 314 Artifact 13.45 4.70 1296.00 18.10 477.75 158.40 1296.00 8.18 1.00 FwJj 25 262 Artifact 26.49 4.74 3714.50 40.98 477.75 413.30 3714.50 8.99 1.00 FwJj 25 257 Artifact 13.45 4.78 1557.50 15.92 163.90 140.10 1557.50 11.12 1.00 FwJj 25 380 Artifact 68.00 4.81 686.95 8.95 77.83 83.19 686.95 8.26 1.00 FwJj 25 304 Artifact 66.30 4.85 677.00 8.89 75.94 82.07 677.00 8.25 1.00 FwJj 25 359 Artifact 6.15 4.89 1484.50 14.74 154.75 136.15 1484.50 10.90 1.00 FwJj 25 327 Artifact 76.47 4.93 713.60 9.27 80.00 86.17 713.60 8.28 1.00 FwJj 25 315 Artifact 66.12 4.97 675.40 9.15 75.01 82.15 675.40 8.22 1.00 RGM1‐S4 Standard 34.73 149.954 108.231 25.395 222.48 8.557 756.976 25.78 15.034 FwJj 25W 63 Artifact 6.65 5.34 1323.44 15.13 177.04 261.63 140.57 5.06 9.42 FwJj 25W 34 Artifact 15.88 5.36 1220.48 15.33 175.71 249.92 139.80 4.88 8.73

246 FwJj 25W 83 Artifact 4.91 5.18 1501.87 15.55 171.20 235.81 139.72 6.37 10.75 FwJj 25W 67 Artifact 4.25 5.35 1586.67 15.94 179.51 250.25 140.88 6.34 11.26 FwJj 25W 56 Artifact 10.48 5.40 1599.24 16.18 178.35 259.23 143.76 6.17 11.12 FwJj 25W 7 Artifact 20.35 5.32 1592.54 16.26 184.23 264.04 144.53 6.03 11.02 FwJj 25W 62 Artifact 6.49 5.44 1562.54 16.37 175.09 238.58 143.41 6.55 10.90 FwJj 25W 39 Artifact 7.64 5.47 1534.46 16.42 179.54 244.59 143.15 6.27 10.72 FwJj 25W 70 Artifact 10.36 5.42 1611.38 16.46 179.26 259.25 142.54 6.22 11.30 FwJj 25W 38 Artifact 6.71 5.53 1553.80 16.66 181.11 246.69 144.78 6.30 10.73 FwJj 25W 10 Artifact 4.08 5.48 1618.83 16.66 192.80 269.22 147.67 6.01 10.96 FwJj 25W 81 Artifact 12.15 5.53 1631.45 16.70 183.35 263.68 146.81 6.19 11.11 FwJj 25W 66 Artifact 3.94 5.51 1568.24 16.90 177.94 238.96 143.29 6.56 10.94 FwJj 25W 52 Artifact 15.36 5.61 1617.87 17.26 182.87 266.65 144.88 6.07 11.17 FwJj 25W 77 Artifact 4.14 5.55 1637.61 17.26 189.24 263.29 147.79 6.22 11.08 FwJj 25W 80 Artifact 3.75 5.67 1677.37 17.32 193.09 269.06 152.09 6.23 11.03 FwJj 25W 65 Artifact 15.91 5.64 1645.94 17.33 186.34 264.71 148.62 6.22 11.07 FwJj 25W 17 Artifact 14.65 5.73 1686.70 17.39 195.72 277.93 115.00 6.07 14.67 FwJj 25W 53 Artifact 15.19 5.90 1704.08 17.80 193.34 267.31 151.49 6.38 11.25 FwJj 25W 79 Artifact 4.17 5.84 1719.24 17.97 203.16 273.68 157.38 6.28 10.92 FwJj 25W 50 Artifact 15.47 5.90 1705.54 18.23 194.16 272.15 153.46 6.27 11.11 FwJj 25W 40 Artifact 5.59 6.16 1766.61 18.65 205.09 280.50 160.78 6.30 10.99 FwJj 25W 49 Artifact 7.79 6.37 1275.52 18.76 107.01 186.30 170.27 6.85 7.49 FwJj 25W 68 Artifact 6.62 6.46 2040.27 19.60 242.36 355.90 171.88 5.73 11.87 FwJj 25W 69 Artifact 23.15 10.73 2502.40 30.04 348.31 462.06 281.51 5.42 8.89 GaJi 4 72 Artifact 432.09 0.62 295.41 1.15 29.91 73.92 12.31 4.00 24.01 GaJi 4 1 Artifact 7.56 3.61 1161.86 1.98 123.64 205.75 105.27 5.65 11.04 GaJi 4 73 Artifact 247.66 2.25 498.97 4.67 61.62 76.98 59.86 6.48 8.34

247

Figure 7.7e: ED-XRF two dimensional plots for Zr/Y and Zr/Nb for Archaeological and geological sources show the use of different sources inclusion North Island some sources remain unmatched

10.00 FwJj 25W 95% conﬁdence eclipse 9.00

8.00

7.00 FwJj 6.00 25W Suguta 5.00 Valley North

Zr/Nb (ppm) 4.00 Island Shin 3.00 Surgei 2.00

1.00

0.00 0.00 5.00 10.00 15.00 20.00 25.00 30.00 Zr/Y (ppm)

248

Figure 7.8: Principal components analysis of trace element chemistry of source samples and artifacts (data is normalized using a logarithmic transformation to insure linear relationships in the variance covariance matrix). 94% of the variation in the data is explained by the first two principal components. The first principal component is positively correlated with Nb (r=.77) and Zr (r=.75).The second principal component is negatively correlated with Sr (r=-.73) and Y (r=-.63) (adopted from Ndiema et al. In Press)

249

Figure 7.9: Principal components analysis of trace element chemistry of source samples and artifacts (data is normalized using a logarithmic transformation to insure linear relationships in the variance covariance matrix). 94% of the variation in the data is explained by the first two principal components. The first principal component is positively correlated with Nb (r=.77) and Zr (r=.75). The second principal component is negatively correlated with Sr (r=-.73) and Y (r=-.63) (adopted from Ndiema et al. In press)

Suguta Valley 250

Figure 7 10: two dimensional of Zr and Zn for archaeological artifacts from FwJj 25w showing all sources are evenly distributed on the stratigraphicaly

3.00 FwJj 25W 2.90

2.80 Surface Scrape 2.70 Level 1(100.7-5) 2.60 Level 2(100.5-3) 2.50

2.40 Level 3 (100.5-99.00) Suguta Valley

Zn (ppm Log10) 2.30

2.20 North Island

2.10 Shin

2.00 2.5 2.7 2.9 3.1 3.3 3.5 3.7

Zirconium (ppm Log 10)

251

7.8 Results from LA-ICP-MS analysis

As previously discussed the impact of raw material variation on lithic tool technology is well documented (Braun 2006; Braun et al. 2009; Blumenschine et al.

2008; Dibble 1995b; Roth and Dibble 1998). As raw material diversity increases within an archaeological assemblage the impact of this diversity on technological variation will also increase. Artifacts from the Mid Holocene deposits at Koobi Fora are made from a wide variety of raw materials (see table 5.1). Clear understanding of lithic assemblage from these mid Holocene sites must incorporate a comprehensive understanding of the context of raw material sources. The variety of raw materials incorporated into the technological repertoire of these ancient tool makers is a product of the extremely heterogeneous geology of Lake Turkana Basin. Fortunately, this variation allows for testing of the effect of different aspects of raw material quality and availability on technological organization. As Shackley (1998) has stated, raw material sourcing studies must incorporate a comprehensive understanding of the primary source geology, so that variation within source can be understood, as well as the paleogeographical implications of secondary sources. This framework needs to be applied to the archaeological material in a manner that allows for the variation within an archaeological sample due to diagenetic modification and behavioral selection to be adequately investigated. Finally, these two data sets need to be integrated to allow behavioral interpretations of the influence of raw material variation on mobility and subsistence strategies. Artifacts need not be linked directly to specific source outcrops 252 but a connection should be made between artifacts and groups of source outcrops that have a similar lithology and can be obtained in similar locations across an ancient landscape.

The use of chemical characterization studies in sourcing archaeological obsidian samples has been proven many times over, and submitting obsidian artifacts for geochemical analyses have become standard practice among archaeologists.

The analytical procedure of 60 samples performed by LA-ICP- MS all the five sites under investigation involved each flake of obsidian having five separate spectra acquired from it for 28 separate elements. Detailed discussion on the analytical methodologies of LA-ICP-MS has been presented above. Here I present the results from this analysis.

To produce quantitative trace-element analyses, LA-ICP-MS requires the knowledge of at least one element in the unknown to act as an internal standard

(usually SiO2 in rhyolitic materials). As no concentrations were known for any elements in the obsidian flakes analyzed, a value of 69.895% was assumed for SiO2 (the same concentration as in the NIST 610 reference material) to act as the internal standard, and to give approximate concentrations. Because of this estimate of the internal standard, the reported concentrations cannot be used directly for comparison (as they are calculated using this assumed value of the internal standard, and not the true concentration). Ratios of one element to another (e.g. Zr/Y, Zr/Nb or any other element pair), however, are correct (as the ratios are independent of the actual concentration), and these can be used in identifying groups within the data (Figure 7.8). It was found 253 that using ratios of Zr/Y, Dy/Yb, Nb/Zn, La/Sm, Mn/V, Zn/Ti, and Ba/Sr to be particularly effective in discriminating different groups of obsidians. With these ratios, scatter plot analysis was performed using PAST to define geochemical source groups, and used the resulting discriminant functions to assign our unknown flakes to geochemical source.

PAST reports the probability of group membership, given the range of variability among the source samples, and we defined a particular cut-off level (p ¼ 0.05), at which the assignment to source was accepted. To avoid any possible confusion, here only plots of the data are presented; the approximate concentration data from which they are derived is not presented, but would be available as attachments at the appendix section.

Shennan (1997:350) describes the application of discriminant function analysis for such purposes as, “One area in which it has found considerable archaeological use is artifact characterization studies, where quantities of trace elements in lithic artifacts or pottery are used to try to discriminate material from different sources.” Principal

Component Analysis (PCA). Principal Component Analysis is a very powerful method of exploratory multivariate statistical analysis, and is often used in the interpretation of artifact characterization (Glasscock 1998). PCA is extremely useful at recognizing relationships within the complex and dense data produced by powerful methods of characterization such as ED-XRF, INAA, LA-ICP-MS (Shennan 1998). PCA produces principal components that maximize the variability present in the sample population.

Much like canonical discriminant function analysis, the first component provides the maximum amount of variability; the second represents the next level, and so on. The 254 principal components produced by PCA are a rigorous method of differentiation that can reduce the dimensions of voluminous datasets without substantial loss of data.

Much of the variability can be represented in the first three principal components; making PCA a very attractive method for data interpretation (Glascock 1998). The intent of this project was not to determine the origin of each archaeological obsidian artifact but, to test the level of variability both within and between the archaeological populations representing each site in order to provide reference baseline data for future artifact-centered endeavors.

Results indicate that sources and artifacts groups can certainly be differentiated using both ED-XRF and LA-ICP- MS analysis. At least five distinct groups were observed using LA-ICP-MS among the geological reference data, representing four sources namely

Suguta, Shin, North Island and Surgei (Figure 7.10). Among the archeological specimens at least five possible distinct groups are represented. The first group comprises samples that form a clear grouping with high Zr/Nb and high Zr/Y ratios (Figure 7.10). This group does not correlate directly with any of the geological sources identified. The second group cluster closer to the identified groups this group also remains unknown.

There are some minor subdivisions evident in this second group that may merit further investigations, for example samples from site FwJj 25W had the highest variation within the entire source with all the identified geological sources represented as well as unidentified groups also being represented. These may be subtle variations on the main groupings, but at present with only a few of each group present it is hard to be precise in defining these groups, if indeed they are real. These sub groups may be related 255 geochemically (similar trace element ratios, etc.) and are likely to have originated from a very similar source, perhaps as a series of lava flows from the same volcano, and may thus be a reflection of subtle compositional differences between such flows. Without comparative material from more Northerly or better resolved central rift valley sources, it is not possible to be certain about the causes of this variation. There is need therefore for more investigation to get more samples. Evidence of multiplicity or diversity of sources was also conformed. FwJj 25W flakes include all the six geochemical types.

While GaJi 4 artifacts were from the four known groups (see figures 7.7a-e).

A site by site plot (Figure 7.7 a-e) of the artifacts shows a more detailed representation in that site FwJj 25W has the highest number of artifacts including North

Island. Site Gaji 4 has also different sources represented.

However preliminarily, the level of differentiation produced by this characterization is extremely encouraging for the application of LA-ICP-MS and ED-XRF towards future comprehensive definition of Lake Turkana basin-wide geological variation, and artifact sourcing. The quarry differentiation achieved through canonical discriminant function analysis provides definitive separation of Lake Turkana basin sources by elemental composition. In accomplishing this task the analysis has identified a “core group” of samples that create the preliminary baseline for future provenance studies; and although the differentiation produced by PCA is less perceptible than two dimensional scatter plots the results are however inspiring.

256

Figure 7.11: LA-ICP-MS two dimensional plot of Nb and Ce for obsidian artifacts from archaeological sites.

3.00 ) 2.90 2.80 FwJj25_Il 2.70 eret

2.60 FwJj27- 2.50 Ileret Cesium (log Base 10 2.40 FwJj5- 2.30 Ileret 2.20 GaJi4- Koobi 2.10 Fora 2.00 1.50 1.70 1.90 2.10 2.30 2.50 2.70 2.90 Niobium (log Base 10)

257

7.9 Relationship between sources and technology through time

It is evident from the foregoing discussion that it is possible to reliably discriminate between different obsidian sources in the eastern Lake Turkana Basin on chemical signatures from LA-ICP-MS and ED-XRF. Indeed, it is even able to discriminate between chemically related sub sources, such as in the Surgei sources. Combined with the data presented from above, this demonstrates that LA-ICP-MS and ED-XRF can be effective and reliable tools for obsidian provenance analysis in the Lake Turkana Basin.

From the foregoing discussion, a range of geochemical types are represented in the flakes, and other geochemical types are notably absent. Table 7.5 shows that in terms of distance, there are at least six groups of obsidians represented at the sites under investigation, those between 30 and 60 km and those between 200 and 250 km from the source and of course those that are unmatched whose distance can not be quantified. This represents the so far known availability of obsidians in the region.

However, these geochemical types were not present in our sample. Interestingly also is the greater average distance of debitage versus formal tools in all the sites, suggesting that these artifact categories record mobility patterns and obsidian acquisition in different ways. Also in line with expectation for high mobility or exchange, when the frequency of different geochemical types are plotted against their distance, from the source versus the percentage of formal tools or debitage, we see no gradual fall-off curves (i.e. distant sources more frequent). Figure 7.12a-d shows these trends. 258

One would have hoped that obsidian artifacts from the nearby sources would be would be higher whereas those from far distant sources would be smaller at all sites.

However there is virtually no difference in tool length and width with distance across all the sites. As seen from Figure 7.12a-d flakes do not get significantly smaller with increase in distance. Moreover, as seen in Table 7.4 there is a structure in the variation of flake length and width as measured by the Coefficient of Variation (CV= standard deviation divided by average). There is little patterning in CV values with distance across all the sites. This could be an indication that that flakes from distant sources (primarily

Suguta ) are just as variable and include the same range of flake sizes from closer sources such as North Island, Shin or Surgei). The complete lack of relationship between size and distance evident in Figure 7.13a-d at these sites was unexpected because one would expect that long distance sources to be highly reduced while the ones in close proximity be less reduced. It appears that more distant sources were essentially at the same stage as of reduction as more proximal ones. It was inferred that these mid

Holocene populations were so mobile that the obsidian raw material that reached the sites basically in the same stage of reduction (resulting in similarly sized debitage), regardless of whether it was 30 or 250 km away. Such incidences of high mobility or exchange are not uncommon as the presence of marine glass bead has been reported at

Jaragole stone pillar site in the Turkana (Nelson 1993).

Based on the interpretation above it would appear that direct obsidian procurement within a mobile settlement system was the norm. Patterns use in obsidian support this interpretation, that is, in favor of direct procurement as the primary means 259 of acquiring obsidian. If exchange had been the preferred acquisition method, presumably within a more sedentary residential settlement system, beyond the issues of quality it is difficult to understand why closer sources, such as Surgei or Shin are not better represented in the debitage profiles, relative to distant Suguta valley source.

At face value the Lake Turkana Basin obsidian figures seem to fit a delayed return model populations travelling long distances to procure resources. However, since we lack the intermediary sites between these sources and our sites with which to plot the expected fall-off in obsidian consumption, these exotic obsidians could equally be indicative of what Renfrew (1977: 48-9) termed a directional mode of exchange, where goods were intentionally taken to a community, rather than making their way to the site

‘down-the-line’. Questions of agency offer additional kinds of explanation for the Lake

Turkana Basin obsidians. For example the specific desires of certain inhabitants or targeted gifts by non-locals/immigrant. Given the extraordinary vast size of the study area one could suggest that the basin acted as a refugia, drawing to it non-locals seeking to alternative or diversified subsistence practice(s).

In the following chapter, I discuss the anthropological significance of the diversity in obsidian sourcing in regional context. I will discuss how this research will clarify key elements of Lake Turkana culture history -were the region’s first herder’s newcomers or longstanding populations?

260 Table 7.4 Sources represented among flakes and summary size statistics by site for ED-XRF and LA-ICP-MS samples

Artifact measurements (mm) Source Distance (km) No Avg. Length CV- length Avg. Width CV-width % of formal Tools % of Debitage GaJi 4 Suguta 250 15 25.5 0.65 31.6 0.35 10 36 Shin 35 2 23.6 0.56 25.8 0.9 5 26 North Island 30 3 20.1 0.54 24.8 0.46 2 21 Surgei 75 13 16.5 0.61 21.9 0.38 8 45 Suguta 250 25 42.4 0.27 23.2 0.59 12 56 FwJj 25 Shin 60 1 20.4 0.31 22.05 0.46 6 23 North Island 30 3 31.5 0.26 16 0.28 3 32 Surgei 60 2 28.4 0.28 24.6 0.32 4 16 FwJj 25W Suguta 275 10 23.6 0.26 27.9 0.23 5 15 Shin 60 12 17.2 0.36 32.6 0.56 3 13 North Island 30 1 25.6 0.26 23.6 0.26 9 6 Surge 60 0 0 0 0 0 2 18 Suguta 275 5 2.6 0.21 9.6 0.18 6 10 FwJj 5 Shin 60 2 12 0.16 26.3 0.12 9 6 North Island 30 4 7.8 0.13 25.3 0.68 2 8 Surgei 60 1 26 0.18 6.8 0.54 13 5

261

Figure 7.12a: Fall‐off curves for geochemical types with distance from site GaJi 4

GaJj 4 GaJi 4

15 y = 0.0309x + 28.722 y = 0.0279x + 3.5345 40

tools 10 30

Debitage 20

of 10

formal

0 %

of 0

% 0 100 200 300 0 100 200 300 Distance from Source (km) Distance from Source (km)

262

Figure 7.12b: Fall‐off curves for geochemical types with distance from site FwJj 25

FwJj 25 FwJj 25 64

y = 0.135x + 17.408 10 56 y = ‐0.0019x + 4.9532 48 8 40 tools

6 32 24 4 Debitage 16 2 8 formal of

0 0 of % 0 100 200 300 % 0 100 200 300 Distance from Source (km) Distance from Source (km)

263

Figure 7.12c: Fall‐off curves for geochemical types with distance from site FwJj 25W

FwJj 25W FwJj 25W 10 20 y = ‐0.0019x + 4.9532 y = 0.0166x + 11.237 8 16 tools 6 12 4 8 formal

of 2 4 % % of of Debitage Debitage of % of 0 0 0 100 200 300 0 100 200 300 Distance from Source (km) Distance from Source (km)

264

Figure 7.12d: Fall‐off curves for geochemical types with distance from site FwJj 5

FwJj 5 FwJj 5

15 12 y = ‐0.0041x + 7.9339 10 y = 0.0147x + 5.6832

tools 10 8 6 5 4 formal

2 of

0 Debitage % of 0 % 0 100 200 300 0 100 200 300 Distance from source (km) Distance from Source (km)

265

Figure 7.13a: Flake length and width versus distance from source for formal tools from GaJi 4

GaJi 4 GaJi 4

30 40 R² = 0.3082 25 R² = 0.6757 (mm) (mm)

30 20 width

15 20 lenght

10 flake

5 0 0

0 100 200 300 Avarage 0 100 200 300 Avarage Distance from source (km) Distance from source (km)

266

Figure 7.13b: Flake length and width versus distance from source for formal tools from FwJj 25

FwJj 25 FwJj 25 30 0.32 y = 0.0161x + 19.848 y = ‐4E‐05x + 0.2842 25 0.31 (mm) (mm)

0.3 20

length 0.29 length

15 0.28 flake flake

10 0.27 5 0.26 Avarage Avarage 0 0.25 0 100 200 300 0 100 200 300 Distance from source (km) Distance from source (km)

267

Figure 7.13c: Flake length and width versus distance from source for formal tools from FwJj 25W

FwJj 25W FwJj 25W

45 30 R² = 0.6372 R² = 0.1853 40 (mm) 25 35 (mm)

20 30

Widht 25

lenght

15 20 Flake 10 15 flake

10 5 5

0 Avarage 0 Avargae 0 100 200 300 0 100 200 300 Distance from source (km) Distance from source (km)

268

Figure 7.13d: Flake length and width versus distance from source for formal tools from FwJj 5

FWJj 5 FwJj 5

35 30 R² = 0.0075 R² = 0.2794 30 25 (mm) (mm)

25 20 20

width 15 lenght

15 10

10 Flake Flake

5 5 0 0

0 100 200 300 Avarage 0 100 200 300 Avarage Distance from source (km) Distance from Source (km)

269

CHAPTER EIGHT

Discussions

8.1 Introduction

In the previous chapters, results on lithic and ceramic technologies were presented

and how they changed through time and space. Geochemical data was for both geological

source samples and archaeological artifacts. The results speak of important differences in

how lithic technologies were organized at Koobi Fora and how stone tools were being

differentially acquired, moved and reduced across the landscape. The diversity in

obsidian raw materials procurement was a result of either exchange and social contacts or

variation in mobility patterns among foragers and early herders. In this chapter,

discussion is more detailed and the implications of those results with the introduction of

domestic stock, especially with regard to mobility patterns and diversification in

subsistence strategies, exchange, and interaction among herders and foragers in

increasingly arid climatic conditions. Changes in interaction patterns and the obvious

implications of introducing domestic stock had a greater effect on the hunter-gather

lifestyle.

8.2 Measuring mobility patterns and raw material sourcing

The use of raw materials from the far flung Suguta valley, source as seen from

most of the sites under investigation, reflects high mobility, large home range, and information or resource sharing despite the largely patchy and unpredictable resource

base in these open environments. One possible explanation for this pattern is that

resources were so sparse, and unpredictable within the environment that movement was very necessary .Here I note that the mobility of hunter-gatherer groups who are also

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food producers is affected not only by the fact that food production (in this case herding)

aggregates resources but creates a form of interaction between food producers and hunting-gathering as they compete for the same resources. Whereas, it may appear that pastoralists are at an advantage over foragers because of the predicable nature of their resource, in some cases this diversity of subsistence base puts foragers at a position of

power since foragers have intimate knowledge of the local environment. This could be

the factor that comes to bear when foragers choose to adopt food production. The use of

pack animals not only allows herders to forage effectively but also to remain in contact

with large groups throughout the year and also maintain contact with the former homelands (Marshall and Hildebrand 2002). The presence of pack animals could also explain the predominant use of obsidian from long distances especially those from the

Suguta and the yet undocumented sources. A combination of these factors acts directly or indirectly to mitigates the effect of resource abundance, predictability, and availability which has such an important effect on mobility and subsistence patterns.

Overall, obsidian geochemical data reveal a diversity of sources for middle to late

Holocene sites. High mobility may be responsible for this diversity, which is consistent with other aspects of the artifact assemblages. The diversity of obsidian sources suggests that groups at these sites had larger procurement ranges, possibly tied to foraging or exchange. The differences in sources apparent at the sites for this study may indicate that groups travelled within different procurement ranges, both within and outside the Lake

Turkana Basin. Inadequate data exist at present to support this inference, but it is an interesting avenue for future work in this area. The idea that these middle Holocene tool

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makers were operating within different procurement territories and interaction zones

needs to be investigated further.

A series of studies have been undertaken to investigate the formation of

geographically isolated of low density site (Binford 1986; Isaac 1984; Potts 1988; Shick

1987). These studies provided the basis for a series of techniques for understanding the

formation of archaeological sites and further expanded the focus of Plio-Pleistocene

archaeologists on landscapes rather than sites (Blumenschine and Masao 1991; Plummer

2004; Potts 1991). Through these studies came the documentation and understanding of hominin transport of materials in and out of archaeological localities (Shick 1987). Out of these studies came the concept of a “flow of stone” from source locations where hominins collected materials to their final destination where hominins discarded artifacts

(Harris 1978; Isaac 1984). These models suggest that as artifacts are deposited away from stone sources they will increasingly become smaller and exhibit evidence of more intense reduction. This is the classic “distance – decay” relationship that defines most studies where raw material availability is seen as a major source of variation in the signature of hominin behavior on stone tools (Renfrew 1977). When variation exists between populations of artifacts made of different raw materials, the distance-decay relationship is usually invoked as an explanation for this variation. Although this model accounts for varying levels of transport costs associated with increasing distances from raw material sources it does not account for other aspects of variation associated with raw material availability, exchange, mobility, and other forms of social cultural interaction.

Furthermore, an accurate assessment of the influence of raw material availability on stone artifact assemblage composition requires an accurate understanding of the availability of

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raw materials and the paleogeographic relationship to archaeological sites. Finally, the

mechanical properties of stone are rarely factored into studies of raw material variability.

Aspects of the physical environmental and properties of stones may not only affect the

functional ability of stone artifacts but also the availability of stone because of the

differential consumption of stone associated with varying levels of raw material quality.

As it has been seen from the above results, local assemblages of lithic

technologies and ceramics assemblages show continuity indicating that any movements

in the region were small scale, and culture contact was more important than migration to

social economic change. Differences revealed through raw material sourcing also needs

to be combined with fine-scale paleoenvironmental data so as to pinpoint changes in

source use in correlation with climate change. These patterns of increased mobility and

perhaps the rise of narrow defended territorial boundaries in environments where food

resources are patchy and unpredictable would have made pastoralism attractive to foragers. The presence of a greater diversity of micro habitats and their increased use of non--local fine grained raw materials is an indication of a large foraging area.

Increasing sedentism can make distant food resources difficult to collect, so that

access becomes unpredictable. One potential response to this crisis is access is to

manipulate the distribution of the resource to satisfy day-to-day or special occasion

needs. In East Africa, this model can explain the domestication and spread of cattle, the

patchy spread of food production, and the late domestication of plants. Marshall and

Hildebrand (2002) have argued that hunter-gatherers in arid settings may have

domesticated cattle to ensure its predictable availability as a food source. Both ecological

perturbations, especially recurring cycles of aridity, and concentration of resources and

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people in lacustrine settings could have precipitated an increased need for predictability.

Given the background of climatic variability against which domestication took place at

Koobi Fora the question remains: how was domestication introduced during the mid

Holocene in marginal circumstances, rather than amidst arid conditions? As earlier

noted, the presence of ceramic-using, delayed-return hunter-gatherers in east Africa

might have led to issues on rights to resources and concepts of ownership associated with such groups. These, are important preconditions for herding (Brooks et al., 1984;

Meillassoux 1972). During droughts, ungulates are a more reliable resource than plants because their populations are maintained through movements that exploit local differences in topography, vegetation, and rainfall (Behnke et al., 1993). Following wild ungulates would have been a particularly attractive strategy for hunter-gatherers of the

Lake Turkana Basin. When faced with variability in the amount, location, and timing of rainfall. The alternative, increasing mobility combined with a more generalized subsistence base, might not have been possible. Generalization would have carried the risk of lowered foraging efficiency (Winterhalder 1986), and the plant component of the

diet was already generalized, requiring use of relatively low-rank resources such as wild

fruits and grains which necessitated cumbersome grinding stones for processing.

Following resilient herds of large wild ungulates, such as cattle or hartebeest, would have

reduced risk and constituted generalization by proxy, because the animals processed more

diverse plant resources than humans could (Gifford et al. 1980). In such arid conditions,

however, locating herds of ungulates would have been difficult, and access to animal products would have remained unpredictable because of erratic rainfall and the high mobility and low densities of wild herds. Sporadic access to herds would have impeded

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attempts to monitor herd size, composition, nutritional status, and the effects of disease

and carnivore predation (Gifford-Gonzalez 2003). This would have limited knowledge of

their condition, and made scheduled consumption events (from large ceremonies to daily

family meals) difficult to plan. Such scheduling would have been especially important to

delayed-return hunter-gatherers of the Mid Holocene in East Africa, because broad social

networks, consolidated by periodic gatherings, would have helped to provide familiar

resources for those in unfamiliar landscapes and spread risks in an uncertain

environment. A ceremonial role for domestic stock at such gatherings would have

provided social, as well as dietary, motivation for humans to achieve or maintain

predictable access to resources.

Local assemblages of lithics and ceramics show technological continuity (Caneva

1988, Caneva and Marks 1993; Haaland 1995; Marks and Mohammed-Ali 1991),

indicating that any movement of population into the region was small-scale, and culture

contact was more important than migration to socio-economic change. Entry of

immigrant groups may have been eased by prior social links as indicated by trade and

common ceramic styles (Bower 1991; Nash et al. In press). Compared to the previous herding environments, the lacustrine environment at the Lake Turkana Basin offered more dependable, productive resources. As noted above domestic stocks are the dominant large mammals at the sites under study which were added to a wide range of wild and aquatic resources. Unlike Saharan/Sudanic or Southwestern Ethiopian pastoralists, herders in this better-watered landscape are thought to have used plants more intensively than their hunter-gatherer predecessors (Garcea and Hildebrand 2009). Site structure and the presence of indirect evidence of plant exploitation, such as grounding

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stones, are present. Today, hunter-gathers still utilize short term rainfall to grow crops

such as sorghum.

Arid conditions c. 6000–3300 BP (Butzer 1982; Harvey and Grove 1982; Owen

et al. 1982) and wild animal diseases (Gifford-Gonzalez 2000) may have slowed the spread of herding in southern Kenya, and made cattle a less predictable source of food than in more northern areas. Cattle moving into areas with wildebeest and buffalo were exposed for the first time to diseases such as Bovine Malignant Catarrhal and East Coast

Fevers. In this frontier context, the low density of herders would have made seasonal aggregations more important, because it would have constrained or allowed for other mechanisms for risk reduction, such as intergroup exchange networks, stock loans, and gifts (Gifford-Gonzalez 1998, 2000), as well as the availability of breeding stock. Hunter- gatherers are thought to have added herding to local hunting or fishing strategies, because

lithics show continuity with earlier East African traditions (Ambrose 1984a; Barthelme

1985).

Whereas detailed explanations of ceramic traditions were outside the scope of this

research and will thus be reported elsewhere, I would like to very briefly comment on the

ceramic traditions and the inception of domestic stock at Koobi Fora. Shifting ceramic

traditions and cultural spheres at Koobi Fora and the adjacent regions during the mid-

Holocene may be linked to major economic transformations. Ceramic assemblages from

Koobi Fora offer contrasting pictures of regional interaction during the mid to late

Holocene. An analysis of these assemblages and the cultural traditions, from which they

come, reveals diachronic changes in middle Holocene social networks. These changes lay

the foundations for the emergence of social complexity such as those reported at the

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Jaragole stone (Nelson 1993) and Namortung’a pillar sites (Soper 1982). Understanding

variations and similarities between ceramic traditions is critical for correctly assigning

mid to late Holocene assemblages at Koobi Fora and recognizing the changing

geographical scales of Holocene cultural orbits. Nderit ceramics that were recovered

from my sites were similar to those that have been recovered as far north as Sai Island in southern Sudan (Brooks et al. 2009; Garcea and Hildebrand 2009). It would seem that pastoral use of the landscape was mobile and extensive, but did not destroy hunter- gatherer habitat, and allowed local hunter-gatherer subsistence and social organization to co-exist. The ceramics they produced indicate participation in a broad network of contacts from as far north as the Sudan and Wadi Howar in the eastern Sahara (Garcea and Hildebrand 2009; Keding 2000; Hoelzmann et al. 2000).

Building on previous investigations suggesting diversity in hunter-gather mobility

and subsistence (Prendergast 2008; Robbins 1984, 2006), my analysis indicates that

hunter–gatherer cultural orbits remained distinct until each gave way to new pastoral

societies. The long coexistence of these two cultural entities is noteworthy for two

reasons. First, Sutton’s (Sutton 1974, 1977; Haaland 1995) description of an ‘‘aquatic

civilization of middle Africa” suggests broad similarities in material culture and

economic orientation across huge swaths of the African continent during the early

Holocene. Such differences may be due to different adaptation patterns to an apparently

similar environment. A second point of interest is the enormous spatial and temporal

extent of these mid Holocene ceramic cultures, even after their divergence from one

another. What fueled the maintenance of common techniques of Nderit pottery

production across thousands of kilometers? Why and how did Nderit cultures remain

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distinct for so long? Potential explanations include both environmental and social factors.

During the early Holocene, abundant rain fell across all of East Africa, and hunter–

gatherers repopulated the East Africa region as it developed lush grasslands with lakes,

fish, and game (Garcin et al. 2009; Wright et al. 2007; Owen 1981; Olago et al. 2009).

As rainfall became less predictable ( Marshall 1990; Marshall and Hildebrand, 2002),

hunter–gatherers inhabiting this relatively arid area might have embraced novel strategies

for obtaining food – such as increased exploitation of wild cereals and other nutritional

plants, increased plant processing, better control over vegetation life cycles – and built

far-flung social networks for information exchange or risk reduction reflected in the

striking spatial continuity of Nderit ceramic production.

The Lake Turkana region would have offered a patchwork of predictable

resources depending on rainfall amplitude and distribution. Regular contacts and

movements between groups would have maximized use of different micro habitats, whereas long-distance North to South or East to West movements within the basin would have been largely redundant in terms of food security and diversity. In the end, lacustrine sites such as those excavated for this study become the receiving grounds for different peoples as desiccation forced them to the lake. The evident sedentary or near-sedentary use of FwJj 25 and 25W indicated by presence of features such as fire places– might indicate that people became increasingly tethered to the lake as rainfall decreased in the middle Holocene.

Gifford-Gonzalez (2003) argues that a likely pastoral strategy for reducing the risk of moving into new areas would have been to integrate with local hunter-gatherer groups, perhaps through marriage alliances ( see also Cronk 1989). In this way, some

278 hunter-gatherers would have assimilated into herding groups, but herders could fall back among hunter-gatherer groups in case of stock loss to drought or disease. Social and economic systems continued to be fluid in the central Rift Valley until recent times: hunter-gatherer and pastoral groups interacted regularly, some hunter-gatherers adopted food production, and pastoralists periodically suffered stock losses (Marshall 1994;

Mutundu 1999; Spear and Waller 1993). During the initial domestication of cattle, concerns about predictable access to animal products would have shaped decisions to adopt livestock, or to move them to new locales.

In eastern and southern Africa, the sustained commitment of time and labor required by herding would not have fitted well with preexisting immediate-return hunting and gathering strategies supported by the region’s comparatively predictable nuts, fruits, tubers, and game. In Africa, hunting and gathering continued both as an independent strategy and as a component of generalized pastoralism (Gifford-Gonzalez

2000; Prendergast 2008). This pattern contrasts with the spread of food production in many other regions of the world. Pastoralists are mobile, with relatively low population densities. They are quite specialized, depending mainly on their domestic species. In addition, the continuous labor of herding presents more scheduling conflicts than farming does for hunter-gatherers adopting food production: domestic plants can be more easily abandoned than animals (Marshall 2000). The form of the earliest food production in

Africa, pastoralism, and the spatial variation in relative predictability of hunting and gathering versus food production, both contributed to the patchy spread of food production so distinctive of Africa.

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8.3 Foragers and the adoption of food production in the Lake Turkana

basin

One of the most notable features of the Lake Turkana sites is the appearance of domestic caprines (and to a much lesser extent, cattle) at some lacustrine sites dating to the mid-Holocene, perhaps as early as 4400 BP. These domesticates become increasingly visible in the faunal record and are clearly part of the diet at sites from the central rift valley, south western Kenya, and the greater Lake Victoria basin.

Overall, the assemblage appears to signify continuity of the different subsistence practices. The Nderit ceramic tradition, with its mainly cross hatched bands and internal scouring, new vessel shapes and lug handles, and different temper and manufacture techniques shows greater links to ceramic traditions documented further North (Caneva

1988; Garcea and Hildebrand 2009; Keding 2000). This spread of domestic stock as widely documented in various literatures might be linked to the presence of better grazing lands in the Turkana basin as one moves into the plains such as the Laikipia plateau, southwestern Kenya and northern Tanzania. The similarity between economies in these sites includes domestic bovids, fish, and diverse wild taxa. The continuity seen throughout assemblages together suggests that the adoption of food production in this

area took place within the forager tradition but not due to intrusive populations or

complete population replacement. This begs the question, how did domesticates first

arrive in Northern Kenya, and why were they consumed by people whose ancestors had

been successful fishers and foragers? The early sites such as GaJi 4 may represent a

“frontier situation between hunter-gatherers and food producers,” (Lane 2004: 255) as

280 seen from decorative similarities between ceramics and those reported from pastoralist sites in Sudan and the eastern Sahara. Rather than arguing for mass migration, evidence seems to be that of “influence” and calls for further investigations using multiple lines of evidence. Given some limited evidence for contact between populations in the Central

Rift based on obsidian studies (Merrick and Brown 1984; Ndiema et al. 2010; Nash et al. in Press; Ndiema et al. In Press) and decorative similarities between ceramic techniques, even those as far as eastern Sahara, the possibility that foragers were in contact with herders in these areas is likely. Long distance exchange networks similar to the hxaro system documented among modern foragers in southern Africa are certainly possible

(Barnard 1992; Wiessner 1982). There is also a possibility of long-distance migration by fisher-foragers, who may have been in contact with herders. In discussing migration,

Dale (2007) cites Anthony’s (1990) argument that populations who specialize in a particular resource will be more likely to migrate due to the risk of overexploiting their preferred food source. In this case, migration routes following lakes and rivers would be highly likely. Apart from matters of quality, preference of obsidian from Suguta source as opposed to the nearby North Island or Surgei supports the argument of movements along water corridors.

Assuming that the foragers at Koobi Fora adopted herding through contact with pastoralists and without a major population change, this scenario agrees with some but not all models of forager variation and the spread of food production. As mentioned in

Chapter 1, Woodburn (1988) argued that immediate-return foragers would successfully survive “encapsulation” by food producers and maintain their way of life due to their adaptability to new conditions, small group size, and high mobility. Delayed-return

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foragers, on the other hand, would be most likely to take on food production, since many

aspects of that system would already be in place. Food production, whether farming or

herding, is the ultimate delayed-return system in that a portion of the potential harvest or

slaughter (i.e., uneaten grain or live animals) is always saved for future sowing or

breeding, and ownership of these resources is very important. Social relationships of

dependence, hierarchy and sexual division of labor, common in food-producing societies,

are also features of delayed-return foraging societies.

Interestingly, this is the exact opposite of arguments that have been made for other

forager-food producer contact situations, especially in Europe (Zvelebil and Rowley-

Conwy 1984, Price 1994). In these frontier scenarios it has been suggested that

Mesolithic complex foragers would hold out longer than immediate-return foragers when

confronted with arriving food producers. This hinges on the idea that delayed-return

foragers would be more self-sufficient, better able to insulate and defend themselves from

others, and/or would have little incentive to switch to a more labor- and capital-intensive

form of economy. As support for this argument, it should ne noted that food production

also was taken up later, circa 2000 years with the late hunter-gatherers in the Rift Valley,

who by all indicators were immediate-return foragers were. This transition, like that in

Turkana, appears to have been made without major population movements based on lithic

continuities between Eburran 4 and Eburran 5 occupations (Ambrose 1998). Thus while I

would agree with Woodburn that delayed-return foragers are particularly well-adapted to pastoralism, this does not mean that they are exclusively so: the spread of food production in East Africa appears by and large to have taken place among immediate- return foraging communities.

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8.4 Models for entry and movement of herders in Northern Kenya

Bower’s (1991) model for the spread of food production in East Africa appears to hold true for Northern Kenya. Bower suggested a “trickle and splash” migration of pastoralists into southwestern Kenya and northern Tanzania ca. 4000 BP; represented by ceramics with ties to the north such as Nderit and Ileret (“Ileret-like” ceramics were identified). As time goes by, and possibly coinciding with the development of a bimodal rainfall pattern ca. 3000 BP (Marshall 1990), an “evolved Pastoral Neolithic (PN)” develops and spreads across the region, manifested in what has been investigated under this project. This phase sees the development of specialized pastoralism (Marshall 1990), with remains of domestic taxa forming ever larger proportions of faunal assemblages, and with discontinuities in ceramics, lithics, obsidian procurement patterns and settlement patterns suggesting major population movements or contact. Bower’s final phase sees a retreat from “evolved PN” as pastoralists enter marginal areas, becoming more mobile, dispersed and prone to hunting to supplement their diet. Bower suggests this phase might be represented by Ileret ware in northern Kenya, but this remains hard to prove.

The meaningful conclusion proposed hence is that the occupants of these sites obtained ceramics with strong similarities to those seen further North. Whether these were obtained through migration of a few wayward pastoralists or through exchange are difficult to say. The paucity of well stratified forager-pastoralist sites in northern Kenya circa 4000 BP, and long delays in their arrival in the central rift valley, also appear to confirm the hypothesis of Gifford-Gonzalez (1998, 2000) that arid regions with tsetse,

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wildebeest and other disease vectors posed challenges to pastoralists to the extent that it

delayed the spread of food production in East Africa.

It seems reasonable that this area represents a “trickle and splash” because it was

hostile to newly-arrived pastoralists. Gifford-Gonzalez (1998) suggests that upon arriving

in an area that presented such challenges, herders were compelled to form exchange

networks and social relationships with indigenous foragers in order to survive, and indeed

the archaeological record from other sites further South in northern Tanzania could be

interpreted as such. It is often thought – based on models from other areas, especially

Europe (Alexander 1977) – that incoming food producers will be at an economic

advantage over foragers. This may simply not be the case in all habitats, and certainly not

in a part of the world that is harsh for livestock herders, even today. Herders may have

been at a distinct disadvantage as they had to learn a new landscape and deal with new

predators and diseases, and foragers may have had the upper hand. This is entirely

speculative, but it is possible that exchanges of goods and information, and even

intermarriages, took place between forager and herder groups, leaving the mixed

assemblages that we see today. If a bimodal rainfall pattern were established by this time

(and it seems likely that these sites date to well after 4500 BP), then this arid grasslands zone would be more accessible to herders, unlike other large sites with abundant ceramics and faunal remains. The setting of the Koobi Fora sites in large, open lakeside grasslands would make them attractive to herders. This raises the question of whether the occupants of PN sites at Koobi Fora are the same population as those occupying earlier sites attributed to Bower’s “trickle and splash” phase. As I emphasized in Chapter 2, the business of correlating material remains with specific groups of people – whether by

284 language, ethnicity or geographic origin is highly tricky and is not emphasized here. But it is worth noting that there is a strikingly high proportion of obsidian at my sites mainly sourced from a diversity of sources including North Island. The diversity of sources could be attributed to high mobility patterns or a major exchange network, possibly connecting to the Sudan or Southwestern Ethiopia.

Bower’s final phase, a dispersal and retreat from the PN is difficult to detect, since by their very nature sites in this phase would leave fewer material traces. Nderit ceramics, suggested by Bower to represent this phase, are present at all the sites reported by in large numbers and in association with Ileret ceramic traditions. More excavations coupled with multiple techniques and multiple-sample dating of more sites in the region, ideally with deep cultural stratigraphy, could help resolve this issue. At the moment, it appears that a flexible boundary between foragers and food producers hovered around

Koobi Fora during the mid Holocene. Interestingly, there is no evidence for past delayed- return foraging in this region and the only foragers remaining today, the delayed-return

Yaaku, have maintained their way of life until very recently, despite a long history of interaction with food-producers (Cronk 1989). This seems to be further proof that

Woodburn’s (1988) encapsulation theory holds true.

8.5 Herder adoption in Turkana Basin and elsewhere

Obsidian provides a geochemically traceable proxy for mobility, exchange, and interaction. This research marked an attempt to remedy this situation, going beyond basic artifact recovery to provide a regional synthesis on mobility patterns based on obsidian

285 procurement. Analyses presented in the previous chapters include faunal skeletal representation, ceramic tradition, lithic artifact technology composition, and obsidian sourcing and characterization. These data are considered together with stratigraphic, chronological and archaeological information from numerous sites to assess settlement patterns, as well as spatial and temporal variation in mid to late Holocene economies. In the process, some questions have been answered and on the other side this has raised many more about the nature, timing, and diversity of early pastoralism not only at Koobi

Fora but across East Africa. Some of these issues are discussed below and also underscore the importance of the Lake Turkana Basin within broader studies of hunter- gatherer and food producer interaction.

It has been argued that pastoralism spread across the Sahara and subsequent desiccation prompted herders to move south. Adoption of food production was patchy despite the overall success of herding. This is largely due to spatial variation in the relative predictability of herding versus hunting and gathering. Difficult terrain impeded the spread of stock into some areas; elsewhere, cattle diseases made pastoralism a risky endeavor. Where herding became established, mobile use of the landscape by small pastoral populations left many local resources intact. Thus, in areas where wild resources were predictable, local groups could continue to hunt and gather well after the arrival of domesticates. Herding is more difficult to adopt than cultivation, especially among immediate-return hunter-gatherers, because of ownership and scheduling difficulties associated with cultivation.

All of these factors led to a distinctively African pattern of slow, patchy spread of food production. Other Old World agricultural complexes often competed more directly

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with local hunter-gatherer subsistence strategies, so that food production was adopted

broadly along a rapidly moving frontier. Mobility lightened selective pressure on local

plant populations; harvesting practices and plant biology may also have delayed

morphological change. Prolonged, intensive use of wild plants across the African

continent led to a non centric pattern of late domestication, and continued use of wild

plants by food producing societies. Early mobile animal-intensive food production may

have had important consequences for subsequent trajectories of social change in Africa.

Pastoral groups require communal access to distant water sources and pastures, and are

often associated with social structures such as age sets that promote wide ranging relationships (Spear 1993).

While pondering mobility among hunter-gatherer and pastoral groups and

wondering how foragers and header interaction might differ from those known from

prehistoric and ethnographic records, rarely considered is the possibility that there might

be a great deal of variation in interaction patterns within and between regions. Yet the

principal conclusion from the obsidian sourcing and characterization and other

archaeological data is that, by a number of indicators, Pastoral Neolithic sites in Lake

Turkana are quite distinct from sites with PN pottery found elsewhere. This should not be

surprising, since great variation has been documented in modern and prehistoric hunter-

gatherer societies that are nominally considered the same “group,” ; for example the

Dobe !Kung of the Kalahari, or the Kasoyore forgers of East Africa who vary

tremendously in economic and social patterns (Cashdan 1984; Kent 2002; Prendergast

2008). Such variation results from ecological conditions, interactions with neighbors, and

cultural factors such as traditions within specific communities.

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Dating efforts over the last five years have confirmed a long chronology originally suggested by Barthelme (1985), which appears to span at least 4500-1000 cal

BP. Such a long time span hints that there should be some diachronic variation between

and within Pastoral Neolithic sites, and indeed Dale (2007) and Prendergast (2008) have

highlighted some of the differences between early and late occupations, largely based on

ceramic decoration and faunal analysis.

A second major difference between the regions is in site settlement patterns.

There is little evidence for contact with the Central Rift during the Mid Holocene, aside

from a single piece of obsidian whose sourcing remains in question, whereas with the

beginning of the Elmenteitan Pastoral Neolithic in Central Rift Valley there is

overwhelming evidence for extensive contact with the obsidian sources of the Central

Rift (Robertshaw 1991; Seitsonen 2004) and northern Tanzania and the flanks for the Rift

Valley. Recent studies (Coleman et al. 2008; Nash et al. in Press; Ndiema et al. 2010, in

Press) have demonstrated lack of contacts between the population in Turkana Basin and

those further South to the flanks of the rift valley at Laikipia plateau. Why wasn’t there

contact between these populations? Several explanations are possible, and more information is needed to test them. One is that expansion south and southeast of the Lake

Turkana Basin happened because those areas were already occupied by foragers and cultural or economic barriers prevented interaction. Gifford Gonzalez’s (2003) work at El

Bor shows that foragers continued to persist in Northern Kenya until the late Holocene.

Perhaps this was due to cultural tensions or barriers between the regions in the Turkana

Basin and their immediate environs. Some sense of territoriality is possible, even with very low population densities, but this is admittedly quite speculative.

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A second explanation, not mutually exclusive with the above, is that early herders

herder and/or forgers who had adopted herding had few options when expanding into

new areas, and therefore could not be choosy, resulting in a lack of clear patterns in site

settlement in this area. The expansion of the makers (or at least carriers) of Nderit

ceramics into the Lake Turkana Basin may represent nothing more than a trickle of

people, perhaps seeking resources such as obsidian, or more hunting or grazing opportunities in the emerging wetland from the retreating lake. On the other hand, Lake

Turkana Basin would have offered a patchwork of predictable resources depending on rainfall amplitude and distribution. Regular contacts and movements between groups would have maximized use of different micro habitats, whereas long-distance north– south or east to west movements within the basin would have been largely redundant in terms of food security and diversity.

In the end, lacustrine sites such as those excavated for this study may have been the receiving grounds for different peoples as desiccation forced them to the lake. The evident sedentary or near-sedentary use of FwJj 25 and 25W indicated by the presence of fire places might indicate that people became increasingly tethered to the lake as rainfall decreased in the middle Holocene.

This is also, of course, is entirely speculative, but it is reasonable to believe that

Pastoral Neolithic material remains clustered around the lake in northern Kenya, with only trickles elsewhere, because of the relative lack of resources in the arid savanna. This would also explain the lack of artifact-rich, deep, multi-component sites in these areas vis-à-vis those that have been reported elsewhere such as in the Lake Victoria Basin

(Prendergast 2008; Lane et al. 2007; Onjala et al. 2005), Gogo Falls (Munene 2002), and

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central rift valley (Ambrose 1998). To start to address this issue in more detail, one

would need a better sense of obsidian sourcing particularly within the entire Turkana

Basin and along the sites in high plateau at Laikipia, as well as the southern end of the

lake, and the earthen margin of the basin such at El Bor and Kargi hills (Nash et al. in

Press)

Finally, there are obvious differences in the manner in which domestic stock were

introduced. High biodiversity, water, and good grazing opportunities near the lake sites enabled this adaptation multiple subsistence strategies and these differences were largely conditioned by environment.

The presence of specialized tools at Pastoral Neolithic sites is not debatable.

There is evidence for bone harpoons at some sites (Barthelme 1985). At the sites no

points have been recovered, though it has been suggested that microlithics may have been

hafted to create compound tools (Seitsonen 2004). Bone points, harpoons, and hafted

tools have been in use since at least the Middle Stone Age (MSA) in Africa (McBrearty

and Brooks 2000; Shea and Hildebrand 2010; Willoughby 2007) and there is little doubt that most MSA and Late Stone Age (LSA) sites were occupied by immediate-return foragers. What, then, constitutes a “specialized tool”? I would argue, following

Woodburn (1980), that these tools require such an investment of skill, labor, and/or raw material that they are not considered disposable, and thus remain with the maker or user.

Since immediate-return foragers tend to shun such tools, not for lack of skill but rather for unwillingness to transport and curate them, we expect specialized tools to be used only by delayed-return foragers. Examples may include spears, harpoons, and nets that I have hypothesized were used by Mid Holocene fishers. Since these would be made from

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almost exclusively perishable materials (except for stone spear tips and footings or net

weights), it seems unlikely that we will be able to detect them in the archaeological

record, barring scientific advances or the discovery of an exceptionally preserved site.

This aspect of the ownership model thus remains theoretical.

As noted in Chapter 2, many have suggested that complex foraging societies,

often antecedents to food production, develop in environments with rich and predictable

resources (Aikens and Akazawa 1996; Hayden 1990). This would certainly seem to be

the case in the Lake Turkana basin: even today, with problems stemming from reduced

lake levels due to damming upper Omo River, Lake Turkana remains one of the worlds’

largest closed water basins in arid northern Kenya, providing a livelihood to large

numbers of households. This productivity was likely even higher in the mid-Holocene,

after a period of extremely humid conditions and high lake levels ca. 9000-6000 BP

(Chapter 3), and with the area supporting a far lower population density. From the faunal

remains it appears there was no shortage of fish. Etiological data suggest that today, the

movements and breeding behaviors of these fish are highly predictable and regulated by

wet/dry seasonality (Stewart 1989). Although the seasonal cycle may have differed in the

mid-Holocene, the responses of these taxa to rainy and dry seasons would have been the

same. Thus knowledgeable fishers and herders could – and, it appears, did – take

advantage of these predictable patterns to establish wet- and dry-season fishing camps. It

therefore appears that, like many areas of the world such as the fisheries of the Pacific

Northwest and coastal Japan, the Lake Turkana basin provided an environment of rich and predictable resources in which a mixed subsistence economic system could emerge.

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Whereas the available data are not sufficient to warrant an argument for specialization, it is important to consider use Mellars (2004) words of caution that one must distinguish between intentional specializations in a single taxon, and “ecological specialization,” i.e. the apparent focus on a specific group of animals or plants resulting from the simple fact that they are the most locally abundant. Determining whether the early herders were focusing or moving across the landscape targeting specific resource such as fish or wildlife – simply because they were the most abundant - would require a level of paleoecological research that is beyond the scope of the present work.

This issue requires more research to assess taxonomic abundance and diversity in the mid- to late Holocene, a challenge when most sites were created through human choices.

In summary, a number of indicators it appears that foragers and herders living around Lake Turkana did indeed practice some aspects of an exchange and cultural interaction, as Dale (2007) has argued based on the evidence from Siror. This makes these foragers not only distinct from modern African foragers (apart from the Okiek), but also distinct from what we know of prehistoric foragers in sub-Saharan Africa. Dale compares Kansyore sites with those occupied by Eburran hunter-gatherers (Ambrose

1984a, 1984b, 1998). Eburran foragers occupied mainly rock shelters, left comparatively little cultural debris, used few or no ceramics, and were mobile generalist hunters who occupied the shelters most intensively during humid periods, when hunting prospects in the forest-savanna ecotone were best. They would appear to be more similar, at least in terms of economy and site settlement, to living immediate-return foragers than were previously known.

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As earlier mentioned faunal remains from northern Kenya sites are sparse and poorly preserved. They suggest generalized hunting of a wide range of ungulates and fishing. Association between remains of domestic animals and Nderit and Ileret ceramics is less certain, but there are few remains of domesticates in general associated with

Pastoral Neolithic contexts. There is certainly no evidence of specialization in a specific

taxon or group of taxa at any of these sites. It might be that wild ungulates, particularly

dry-adapted bovids and equids, constitute a rich and predictable resource in the area, but

it would be difficult to justify this without good paleoecological data.

8.6 Conclusions In this discussion I have highlighted some of my findings regarding early foragers and Pastoral Neolithic economies in Koobi Fora in particular and East Africa in general.

Four major points can be taken from this discussion. First, there is great variation among sites with obsidian sources and particularly the sources within the basin in Turkana Basin.

These differences are so great that one might question whether or not they should be considered the same cultural entity. Second, within the Lake Turkana basin, there are two main site types that appear to form a complementary, possibly seasonal system of settlement and subsistence. Evidence I have gathered suggests that forager fresh water springs sites (see chapter 3 for local geology of FwJj 5) were used as temporary rainy season camps, while lake side sites (see Chapter 3 local geology sites) were repeatedly used as base camps during the dry-season, or perhaps visited year-round. This level of economic and social complexity, together with a number of other indicators, suggests that

Lane’s (2004: 255) application of the “frontier” and “static frontier” model to the timing rate and strategies of food production was completely warranted. Third, later Pastoral

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Neolithic sites in the study area are notable for the introduction of domesticates, apparently within a continuous cultural tradition, rather than through major population shifts or outside influences. Again, the periphery has little to no evidence for such an

introduction. Finally, evidence from Pastoral Neolithic sites in the peripheral zone

suggests that Bower’s (1991) model for the spread of pastoralism is a reasonable

explanation for the different site types documented in this region, from “trickle and

splash” occurrences with few ceramics or remains of domesticates to “evolved Pastoral”

sites with abundant ceramics and many remains of domestic animals. The mixed

assemblages typical of this region reflect interactions and exchanges between food

producers and foragers, which may have been stimulated when herders found themselves

up against new challenges in unfamiliar terrain.

All of these broad conclusions come with their caveats and questions, as I have

noted throughout the discussion above. In the next chapter, I outline some of the most

thought provoking questions posed by this study and ways future researchers might

address them.

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CHAPTER NINE

Conclusions and Directions for Future Research

9.1 Summary

In the previous chapter I have shown that the diversity of raw materials is variable in two ways: First, they are distinct from sites to site, and second, they are variable within the site themselves. The uniqueness of such raw material variability can be summarized by two broad conclusions. First, data from the greater Koobi Fora show that these sites seem to have been occupied by a population practicing a highly mobile economic system.

This raises a series of questions about factors leading to the adoption of sedentary lifestyles: for example, the argument that delayed-return economies emerge only at extreme latitudes should be re-examined. It seems much more likely that a habitat of rich and predictable resources, in this case wild and aquatic resources, is extremely encouraging to the adoption of different subsistence systems, wherever in the world they may be. My conclusions also suggest that in Africa, at least, there was a strong emphasis on prehistoric immediate return foraging societies with an assumption that they are similar to those documented today.

Nevertheless, following Marshall (2005), It can be argued that when using well- defined “relational analogies” (Wylie 1985), preferably focused on functional rather than social questions, we can use ethnographic analogy to better understand the prehistoric record. The second broad conclusion is that early foragers were active participants in the adoption, and possibly the spread, of herding. The large quantities of remains of domestic stock at the studied sites, suggests that this was not just occasional consumption of an

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animal acquired through exchange or some other socio-cultural practice such as raids.

Since there is no major change in material culture between the sites dating the mid

Holocene (GaJi 4, FwJj 25 and FwJj 27) and the later Holocene sites (FwJj 5). Apart

from a possible shift in decorative motifs, this change must have taken place within the

hunter-gatherer tradition, rather than coming from outside. Notably, foragers continued to

hunt and fish, as did the later occupants of some Pastoral Neolithic sites.

Beyond this research area; the origins, timing and the manner in which herding

was introduced and adopted remains somewhat of a mystery. Following Gifford-

Gonzalez (2000), it seems likely that migrating pastoralists faced a series of challenges –

possibly related to aridity, new predators and new diseases affecting their livestock – that forced them into hunting/foraging and exchange relationships with local hunter-gatherers,

producing the mixed assemblages recovered in our sites. Together, the data from these

five sites raise many more questions than they answer. Some of these questions can be addressed through relatively simple analyses, others will require multidisciplinary teams and large amounts of time and funding. Still, these challenges are not unbeatable and so I present them here in hopes that future researchers will take them on.

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9.2 Directions for Future Research

Here I outline some avenues – both narrow and broad – for potential investigations in the future:

1) High resolution studies on seasonality in the Lake Turkana basin

In Chapter 5, I proposed a seasonal round of site settlement and subsistence in the

Koobi Fora, largely based on relative abundances of fish taxa, etiological data for these taxa, and site locations. A more scientific approach to seasonality should be taken when possible. Seasonality studies are most effective at temperate latitudes, but some (not all) of their methods might be adaptable to the wet/dry seasons of the tropics.

One of the best-known methods of addressing seasonality is through incremental growth structures in dental cementum of herbivores: alternating bands in cementum have been shown to reflect seasonal variations in food hardness and available nutrients. This method has been applied to sites in Southwest Asia, Europe, North America and most recently

South Africa (Lam 2008). It seems likely that this method would not work at tropical latitudes, given its dependence on temperature; but recently evidence of wet/dry season variation in the cementum among East African ungulates has been presented (O’Brien

1994, 2000). Where as O’Brien’s data was from bone assemblages from modern fauna, application of his techniques in archaeofaunal remains including fish, should be considered

2). Fine resolution dating of PN sites in Turkana Basin

Thanks to the efforts of Ashley et al. (in press) Barthelme (1985), Marshall et al.

(1984), Kiura (2008), Ndiema et al. (2010, In press), Nash et al. (In press) in Lake

Turkana combined with the research presented here, we now have a series of reliable

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dates for Pastoral Neolithic sites at Koobi Fora. These confirm the long chronology

originally suggested by Bower (1991) and provide a means of dividing the Pastoral

Neolithic at Koobi Fora into early and late phases (Ashley et al. in press). Nothing of this

kind existed before making dates problematic and the co-occurrence of ceramic traditions

and lack of stratigraphy makes establishing a cultural sequence difficult.

One solution may be to directly date either ostrich eggshell or ceramics. Since

ostrich eggshell beads can easily migrate downward in disturbed deposits, and decorated

ceramics can be more conclusively tied to a cultural tradition, dating the latter would be

better. Several methods are possible (Bonsall et al. 2002). First, organic temper can be directly dated via AMS radiocarbon analysis. One danger of this is that clays may contain

very old carbon, and if these are included in the sample they may give an exaggerated old

date. Second, temper may include shell, which can absorb high amounts of carbonate.

Third, soot from fuel (during firing or cooking) can contaminate the pottery, resulting in

an “old wood” problem. Finally, contamination in the burial environment could also be

problematic. A second method is Thermo Luminescence (TL) dating, which gives the last

time crystals in clays were heated to a high temperature (ca. 400-500°C) that is when they

were fired (Aitken 1990). Thermo Luminescence has been met with skepticism, largely

due to unknowns about background radiation in the burial environment. This particularly

affects museum collections since sediments around the ceramics cannot be sampled. A

related problem is that Thermo Luminescence dates often have large margins of error.

Nonetheless, Feathers (2003) argues that new techniques and instrumentation make this

technique; another advantage is that the method provides dates in calendar years,

avoiding the thorny problems of C14 calibration.

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If direct dating of Pastoral Neolithic ceramics were successful, it would be a interesting

to those involved in understanding the social and economic interface between fishing/hunting/gathering and herding.

3) Functional analysis of Nderit and Ileret ceramics

Some researchers have argued that ceramics – particularly highly decorated ones

–played a symbolic role in foraging economies (Close 1995; Hayden 1990; Kinahan

1994; Vitelli 1989). This may be the case, but given the quantity of ceramics at Pastoral

Neolithic sites, which appear by all indicators to be functional, consumption and living areas, it seems likely that ceramics also had a functional role. They may have been

receptacles for cooking, food preparation, and even transport; they would also ease

cooking of other foods such as grains. Further studies on the function played by ceramics

would be very informative. Residue analysis is a well established way of detecting dairy

products, meat, fish, leafy vegetables and other foods producing oil or wax, though

residues will usually reflect only the last uses of the vessel. Differentiating these sources,

however, is another matter: fatty acid analysis, protein analysis, and compound-specific

stable isotope analysis are successful methods (Barnard et al. 2007; Evershed et al. 1997,

2001). Detecting dairy products and fish lipids and differentiating them from others is

particularly tricky (Brown and Heron 2005; Olsson and Isaksson 2008). However, given

the reasonable hypothesis that ceramics at Lake Turkana sites were used for food

processing and/or storage, residue analysis would be worth exploring.

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4) Large scale excavation of late Holocene sites in Lake Turkana Basin and

beyond

The results from this has shown that this is a potentially fruitful and relatively unexplored area for research on the slow, variable and patchy spread of food production.

Problems with sites in this region include poor bone preservation, a lack of datable substrates and thin, mixed occupational levels. However, the absence of evidence for intensive, semi-sedentary occupations is just as interesting as their presence: it suggests that this region was home to highly mobile herders and foragers. We do not know the tempo at which pastoralists moved south. Sheep-based economies reached southwestern

Africa and the Cape perhaps between ca. 2000-1600BP, and more conclusively by 1600

BP (Sealy and Yates 1994). The prevailing theories are either that the sheep were brought directly south from West Africa by iron-using agro-pastoralists, leaving out East Africa altogether, or that they came from East Africa with stone-using pastoralists (Smith 2005).

In either case, what happened over the ca. 800 kilometers between the Lake

Turkana Basin and the central Rift Valley and south western Kenya is sparsely documented, not least due to obstacles to research in some areas, but also perhaps because the grasslands and lakes south of the Turkana basin were so tsetse infested that they were inaccessible to stone-using pastoralists, and the few who entered were so mobile that they left almost no traces. More excavation of sites in this gap would be informative.

Extensive survey will be needed to detect sites, particularly considering the expanse of the grasslands along the Laikipia plateau and the presence of bone-destroying carnivores.

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Though extensive work is needed, equally important are large scale excavations, focusing

on known areas of occupation and searching for signs of pastoralist habitations such

cattle enclosures.

In the past, Pastoral Neolithic sites in northern Kenya were excavated using

traditional approaches. More effort should be made to recover manure, phytoliths and

micromorphological samples, which could point to livestock enclosures and other features of pastoralist settlements (Robertshaw 1988; Shahack-Gross et al. 2003;

Shahack-Gross et al. 2004). Also, dung deposition leads to enriched levels of a stable isotope of nitrogen (15N), which can be detected through sediment analysis (Shahack-

Gross et al. 2008). Phosphates in soils can also identify livestock enclosures, but the main problem here is equifinality, since a number of anthropogenic and biogenic activities can lead to their deposition (Aston et al. 1998; Haslam and Tibbett 2004). Finally, large scale excavations are needed to expose levels attributed to pastoralists would be useful to identify penning, living and storage features, which may only be detectable through changes in sediment color, compaction and chemistry, using ethnoarchaeological data from modern pastoralist settlements as a guide.

5) The role of livestock disease in the spread of pastoralism: a multidisciplinary

approach

In two important papers, Gifford-Gonzalez (1998, 2000) attributes delays in the spread of herding – first from Lake Turkana to the Central Rift Valley and northern

Tanzania, and then to southern Africa more than two millennia after its first appearance in Turkana – to a series of animal disease challenges faced by migrating pastoralists.

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These include trypanosomiasis or sleeping sickness (transmitted by tsetse fly), East Coast

Fever (transmitted by ticks), rift valley fever (transmitted by blood-sucking insects), foot-

and-mouth disease (carried by buffalo), and malignant catarrhal fever (carried by

wildebeest). They only affect cattle, which may explain why caprines dominate the

remains of domestic taxa in early sites in East Africa, and why sheep are the first to arrive in southern Africa. Disease-related obstacles were eventually overcome with increased knowledge of the landscape and how and when diseases would be transmitted; today cattle herders modify the landscape and/or their grazing routes with such knowledge in mind. As I noted in the previous chapters, exchange of foods, pots, marriage partners and ecological and technological knowledge may have been strategies to build alliances and minimize risk for both groups, but particularly for pastoralists. This may explain the co- occurrence of “pastoralist” ceramics and wild fauna, the low frequency and density of

Pastoral Neolithic sites, and the few remains of domesticates. While Gifford-Gonzalez

(2000) has already laid much of the groundwork for studies of animal disease in East

Africa, future research could focus on at least three issues. First, further survey and excavation could lead to more precise mapping and dating of herders’ land use patterns.

Detailed maps of the ranges of disease hosts and transmitters (some provided by Gifford-

Gonzalez 2000) should be compared with precise faunal and chronological data. Second, we should consider that some of the diseases described above could be visible as pathologies in cattle skeletal remains, if not macroscopically then perhaps in bone histology.

To my knowledge this is an under-explored area of research; although nothing

may come of it, there is plenty of available faunal material and it is an avenue worth

302 exploring. Third, Gifford-Gonzalez notes that indicine breeds of cattle (zebu), originating in South Asia, likely had no resistance to the diseases such as trypanosomiasis. Taurine breeds (from Africa, Europe and southwest Asia) may have had some resistance, but this is unclear: modern West African breeds are resistant, but modern East African breeds are not. While perhaps being susceptible to tsetse, zebu does have higher tolerance for heat and aridity (Ittner et al. 1951), which might have made interbreeding them with local stock advantageous, particularly as herders moved south. Identifying breeds in cattle remains has been challenging (Grigson 1991; Marshall 2000), but advances in archaeogenetics and in genetic ancestry studies (using modern samples) may prove useful in this regard (Bradley et al. 1998; MacHugh et al. 1997). Recovery of ancient DNA from cattle remains would be highly informative. From there, mapping the location and timing of the appearance of indicine stock, and comparing these data with the geographic range of disease transmitters, could help explain why and when pastoralists were eventually successful in covering large areas of the landscape in eastern Africa.

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6) Scientific approaches to ranging patterns across the landscape

Two major migration issues have been raised by the present work: connections between Nderit and Southern Sudan and South Western Ethiopian sites and the southward spread of pastoralism. As suggested above, further survey, excavation and ceramic studies in these areas will help; but these are long-term projects that face political and logistical obstacles. If we are working on the hypothesis that there was indeed population movement and not just sharing of material goods and ideas, then another avenue of research would be to use strontium analysis in human skeletal remains to determine population movements. The ratio of two isotopes of strontium (87Sr/86Sr) in bone and tooth enamel is related to geological substrates in the area of occupation, which enter the body via soils, water and then the food chain: simply put, the older the rock, the higher the ratio (Beard and Johnson 2000; Bentley 2006). This method requires a detailed knowledge of the geology of the site surroundings and the hypothesized areas of origin.

Fortunately the geology of Turkana basin is extremely well documented, but sampling of groundwater, rivers, and excavated animal teeth or small animals is still needed, and is no small task (Bentley et al. 2004; Price et al. 2002). Another issue is that non-local signatures do not necessarily indicate intrusive population movement but could reflect local populations moving temporarily to another area, perhaps for exchange or resource procurement ( such as obsidian). A third issue, particular to East Africa, is that the cycles of uplift, volcanism and erosion that created the Rift Valley may have led to mixing of signals to such an extent that different regions cannot be differentiated. This possibility should be explored before major research is undertaken. To date; strontium analysis in

Africa has been limited to Pleistocene deposits in South Africa (Sillen et al. 1995), Egypt

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(Buzon et al. 2007), and the Holocene deposits in the Libyan Sahara (Tafuri et al. 2006); the latter study, of Saharan pastoralist mobility, shows the potential for future work along this subject matter. Human remains have been recovered from ten several Holocene site at Turkana Basin including one of the sites under this study( FwJj 27) all of these are isolated elements, and the more-reliable teeth are not always present. At some sites, association of human remains and Pastoral Neolithic ceramics is dubious. This meager sample at least serves as a starting point.

The question of southward-migrating pastoralists is even thornier. Uncritical associations between ceramics and peoples/economies are very variable, and the data in the previous chapters show that Pastoral Neolithic ceramics and the herding of sheep, goat and cattle do not always move in tandem. New challenges may have forced migrating herders into hunting and into contingent relationships with local hunter-gatherers, and hunter- gatherers may have acquired or made ceramics as a result. Material remains are not the best means of addressing migration.

Again, strontium analysis could be useful, especially since human remains are much more abundant at Holocene sites at Turkana basin. Additionally, obsidian sourcing could be informative, though it cannot distinguish between long-distance exchange and population movement.

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Curriculum Vita

Emmanuel K. Ndiema Educational 2005‐ 2011 PhD, Department of Anthropology at Rutgers, The state University of New Jersey (USA) 2007‐ M A in Anthropology, Rutgers the State University of New Jersey, my research was on “Modeling the spatial dynamics of Early Pastoralism at Koobi Fora Kenya” 2002: M.A in Archaeology, University of Nairobi. My research was on “Human Adaptive Strategies. During the Holocene in Eastern Lake Turkana: A Micro‐ wear and functional analysis” 1999: University Of Nairobi, BA Archaeology & literature (Second Class Honors Upper Division)

Professional Employment 2008‐Present: Research Scientist National Museums of Kenya Department of Earth Sciences 2007‐Present: Field Director Koobi Fora Field School of Paleoanthropology (Rutgers University and National Museums of Kenya) responsible for leading lectures and directing filed excursions in the Holocene Galana Boi Formation. 2007/9‐ Lecturer, Department of Africana Studies, and Centre for African Languages, Rutgers University, USA 2004/6: Instructor Koobi Fora Field School (Rutgers University and National Museums of Kenya) was responsible for leading lectures and field excursions. 2004: Trust for African Rock Art (TARA), Rock art exhibition coordinator, was responsible for recruiting and training of exhibition attendants and the general running of the exhibition. 2003: Teaching assistant Koobi Fora Field School (Rutgers University and National museums of Kenya) was responsible for teaching undergraduates on mapping, excavations and field survey using GIS and EDM machines. 12/2002‐3/ 2003: Assistant project director, Karari Archaeological project East Turkana. Creating topographic maps using laser theodolite, collecting geological and paleo‐enviromental data and conducting excavations.

Publications Ndiema K.E, et.al (in press). Transport and Subsistence Patterns at the Transition to Pastoralism, Koobi Fora, Kenya. Archaeometry

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Ndiema K.E, (2011 “Heritage Experts Meet in El Smara, Morocco to Discuss Strategies for Safeguarding Africa’s Rock Art”. Centre for African studies Newsletter Spring 2011, Vol XVII. Ndiema K.E, (2010) Development intervention or Rock Art Vandalism? Insights from North‐ Rift valley, Kenya Paper presented at an International rock art conference on “conservation of African rock and challenges in the face of threats of theft and vandalism” at El Smara, Morocco 19th‐21th August 2010 Ndiema K.E, et al. (2010). Interaction and Exchange across the Transition to Pastoralism, Lake Turkana, Kenya. In C.D. Dillian and C. L. Brown (Ed), Trade and Exchange: Archaeological studies from History and prehistory, Springer, New York, pp. 95‐108. Ndiema K.E,et al. (2009) Modeling mobility patterns of Early pastoralism at Koobi Fora Kenya: evidence form Obsidian Sourcing and Characterization. Paper presented at the 2nd East Africa Association of Paleontologists and Paleoanthropologists (EAAPP), meeting at Arusha, Tanzania 19th‐25th August 2009. Ndiema K.E, (2009) Ancient pastoralism lifestyles at Koobi Fora Kenya: evidence form Obsidian Sourcing and Characterization. Paper presented at the 2nd East African Quaternary Association (EAQUA) meeting at Addis Ababa, Ethiopia 19th‐25th April 2009. Ndiema K.E, (2008) Subsistence change in east Africa: Geochemical evidence of obsidian potential indicators of replacement verses continuity. Paper presented at the ”Fishers to Herders Workshop” Stony Brook University New York , Oct 14‐18th 2008. Ndiema K.E, Braun D, and Dillian C L. (2008) Pastoralist ranging patterns: New perspectives from Koobi For a Kenya Paper presented at the Society of Africanist Archeologists (SAFA) Conference, Frankfurt , Germany Sept 7th‐ 11th 2008. Ndiema K.E, Braun D, and Dillian C L. (2008) Holocene Pastoralists Adaptations in East Africa: How similar or different was it from that of South Africa? Paper presented at the Association of Southern African Archaeologists (ASAPA) s Conference, Cape Town RSA, April 25‐30th 2008. Ndiema K.E, Braun D, Dillian C L. (2007) Mid‐Holocene Pastoralists Adaptations in East Africa, Evidence from Geochemical Analysis of Obsidian Sources and Artefacts from Koobi Fora, Kenya. Paper presented at a Society of American Archaeologists Conference, Austin, Texas, and April 25‐29th 2007. Harris J, Bagine R. Kiura P, Ndiema E, Dibble L (2007) “Vegetation Wildlife and domestic stock: a perspective from Sibilio national park and surrounding areas Northern Kenya” Paper presented Kenya wildlife research imperatives for wildlife conservation & management conference Nairobi Kenya April 2007. Ndiema K.E, Braun D, Harris J, Bitting K., Kiura and Dibble L. (2006) Predictive modelling of Holocene archaeological sites, from the lake Turkana basin, Galana Boi

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Formation. Poster presented at a Conference on Computer applications in archaeology (CAA), Fargo April 18‐21st, 2006. Ndiema K Braun and Harris J (2006).Predictive Modelling of Holocene lifeways from Koobi Fora, Northern Kenya. Poster presented at the Society of Africanists Archaeologists held in Calgary, Canada 19th‐24th June 2006. Ndiema K. E. (2004), New perspectives on rock art from Mt Elgon and Kara‐Pokot, Proceedings of the International conference on rock art Nov.1‐3 2004 Nairobi, Kenya Ndiema, K. E. (2003) Archaeological Investigation of Rock Art sites in Mt Elgon and Kara‐ Pokot region Paper presented at a Conference on Archaeological and Paleotological research in Kenya, Nairobi Kenya. August 9th. Ndiema, K. E. (2002) Actualistic studies on Goat Butchery using Acheullian Technology Talk Presented to the Prehistory club of Kenya. Nov.24th.2002.