site reconnaissance in the kipsing and tol river watersheds of central kenya: implications for...

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African Archaeological Review, Vol. 21, No. 3, September 2004 ( C 2004) Site Reconnaissance in the Kipsing and Tol River Watersheds of Central Kenya: Implications for Middle and Later Stone Age Land-Use Patterns D. Bruce Dickson, 1,6 Frederic B. Pearl, 2 G.-Young Gang, 3 Samuel Kahinju, 4 and Simiyu Wandibba 5 Two seasons of archaeological site reconnaissance and geo-archaeological field- work in the Kipsing and Tol river valleys of central Kenya have resulted in (1) the location of 58 surface sites and 13 spot finds and (2) the excavation and dating of 11 alluvial stratigraphic profiles. These data are incorporated with our previous work in the study area to yield a preliminary interpretation of Middle and Later Stone Age tool technologies and land-use strategies during the Late Pleistocene period there. Specifically, the nature of the lithic inventories and observed distribu- tion of archaeological sites suggests that people in the Middle Stone Age employed a “patch choice” resource and land-use strategy while those in the subsequent Later Stone Age period utilized a “logistical” strategy. Pendant deux saisons de la reconnaissance arch´ eologique d’emplacement et des travaux sur le terrain geo-arch´ eologiques les vall´ ees dans de Kipsing et de Tol fleuve du Kenya central ont eu comme cons´ equence (1) l’endroit de 58 emplacements ext´ erieurs et 13 trouvailles de tache et (2) l’excavation et dater 11 profils stratigraphiques alluviaux. Ces donn´ ees sont incorpor´ ees avec nos travaux pr´ ec´ edents dans le secteur d’´ etude pour rapporter une interpr´ etation pr´ eliminaire de milieu et de strat´ egies post´ erieures d’utilisation de la terre de technologies d’outil de ˆ age de pierre pendant la p´ eriode pl´ eistoc` ene en retard l` a. Sp´ ecifiquement, la nature des inventaire lithic et la distribution observ´ ee des emplacements arch´ eologiques sugg` ere que les gens dans le ˆ age de pierre moyen 1 Department of Anthropology, Texas A&M University, College Station, Texas. 2 Department of General Academics, Texas A&M University at Galveston, Galveston, Texas. 3 Department of Cultural Anthropology, Yeungnam University, Taegu, Republic of Korea. 4 Archaeology Division, National Museum of Kenya, Nairobi, Kenya. 5 Institute of African Studies, Nairobi, Kenya. 6 To whom correspondence should be addressed at Department of Anthropology, Texas A&M University, College Station, Texas 77843; e-mail: [email protected]. 153 0263-0338/04/0900-0153/0 C 2004 Plenum Publishing Corporation

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Page 1: Site Reconnaissance in the Kipsing and Tol River Watersheds of Central Kenya: Implications for Middle and Later Stone Age Land-Use Patterns

African Archaeological Review, Vol. 21, No. 3, September 2004 ( C© 2004)

Site Reconnaissance in the Kipsing and Tol RiverWatersheds of Central Kenya: Implications forMiddle and Later Stone Age Land-Use Patterns

D. Bruce Dickson,1,6 Frederic B. Pearl,2 G.-Young Gang,3

Samuel Kahinju,4 and Simiyu Wandibba5

Two seasons of archaeological site reconnaissance and geo-archaeological field-work in the Kipsing and Tol river valleys of central Kenya have resulted in (1) thelocation of 58 surface sites and 13 spot finds and (2) the excavation and dating of11 alluvial stratigraphic profiles. These data are incorporated with our previouswork in the study area to yield a preliminary interpretation of Middle and LaterStone Age tool technologies and land-use strategies during the Late Pleistoceneperiod there. Specifically, the nature of the lithic inventories and observed distribu-tion of archaeological sites suggests that people in the Middle Stone Age employeda “patch choice” resource and land-use strategy while those in the subsequentLater Stone Age period utilized a “logistical” strategy.

Pendant deux saisons de la reconnaissance archeologique d’emplacement etdes travaux sur le terrain geo-archeologiques les vallees dans de Kipsing etde Tol fleuve du Kenya central ont eu comme consequence (1) l’endroit de 58emplacements exterieurs et 13 trouvailles de tache et (2) l’excavation et dater11 profils stratigraphiques alluviaux. Ces donnees sont incorporees avec nostravaux precedents dans le secteur d’etude pour rapporter une interpretationpreliminaire de milieu et de strategies posterieures d’utilisation de la terre detechnologies d’outil de age de pierre pendant la periode pleistocene en retardla. Specifiquement, la nature des inventaire lithic et la distribution observee desemplacements archeologiques suggere que les gens dans le age de pierre moyen

1Department of Anthropology, Texas A&M University, College Station, Texas.2Department of General Academics, Texas A&M University at Galveston, Galveston, Texas.3Department of Cultural Anthropology, Yeungnam University, Taegu, Republic of Korea.4Archaeology Division, National Museum of Kenya, Nairobi, Kenya.5Institute of African Studies, Nairobi, Kenya.6To whom correspondence should be addressed at Department of Anthropology, Texas A&MUniversity, College Station, Texas 77843; e-mail: [email protected].

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0263-0338/04/0900-0153/0 C© 2004 Plenum Publishing Corporation

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aient utilise un “choix de morceau” (“patch choice”) strategie de ressource etd’utilisation du territoire, alors que ceux dans la periode posterieure suivante deage de pierre utilisaient un “logistique” strategie.

KEY WORDS: Middle Stone Age; Later Stone Age; Kenya; Mukogodo Hills; land-use strategies.Mots-cles: Age de pierre moyen, Age de pierre posterieur, Kenya, collines de Mukogodo, strategiesd’utilisation du territoire.

INTRODUCTION

This paper presents data obtained from components or occupations foundon 58 sites and 13 spot finds located in 1996 and 1999 during two field seasonsof systematic archaeological site reconnaissance in the Tol and Kipsing rivercatchments as well as an analysis of the 11 alluvial stratigraphic profiles excavatedthere. We begin with a description of the catchment study area in the Mukogodohills and upper Ewaso Ng’iro plains region of central Kenya. The sequence ofalluvial deposition there as obtained from our 11 stratigraphic profiles is presented,and the sequence of archaeological occupation in the study area is discussed. Thegoals, methods, and results of our systematic site reconnaissance are reviewed,and the analysis of the lithic and ceramic materials collected from the site surfacesis summarized.

These new data are combined with the previously reported results of our testexcavations in the Shurmai (GnJm 1) and Kakwa Lelash (GnJm 2) rocksheltersites (Dickson and Gang, 2002; Gang, 1997, 2001; Kuehn and Dickson, 1999) toyield a preliminary interpretation of Middle and Later Stone Age tool technologiesand land-use strategies in the study area during the Late Pleistocene period. Weconclude that the nature of the lithic inventories and the observed distribution ofarchaeological sites suggests that in the Middle Stone Age people employed a“patch choice” resource and tool technology and land-use strategy while those inthe subsequent Later Stone Age (LSA) utilized what Binford (1980) has referredto as a “logistical” strategy.

MUKOGODO HILLS/UPPER EWASO NG’IROPLAINS OF CENTRAL KENYA

The Mukogodo Hills are a rugged, dissected, and heavily forested range oflow mountains and inselbergs that lie on the eastern rim of the Laikipia Plateaunear the boundary between the central highlands and northern lowlands regionsof Central Kenya. Facing south from these hills on a clear day, one can see therugged peaks and upper slopes of Mount Kenya on the horizon. Descending thesehills to the north and east, thick woodlands give way, first, to open acacia forests,and then to parkland, and finally to brushy grasslands of the upper Ewaso Ng’iroplains (Fig. 1). The slopes of the Mukogodo Hills form part of the watershed of the

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Fig. 1. Map of Kenya showing the location of the Mukogodo Hills and Upper Ewaso Ng’iro plainsstudy area.

upper Ewaso Ng’iro River. Its large catchment includes such towns as Nanyuki,Isiolo, Wamba, Don Dol, Archer’s Post, and Kipsing. The Ewaso Ng’iro is aperennial stream fed by several large tributaries. One such tributary is the Kipsingriver, which forms one of the few rectangular drainages in an otherwise dendriticsystem (Hackman et al., 1989, pp. 6–7). Its drainage network is constrained by thetrends of the underlying gneiss that form the Mukogodo Hills. The Kipsing river

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is fed by three ephemeral tributaries: the Sinyai, Tol, and Seaku Rivers. The TolRiver is a 20-km-long third-order stream that incises the plain between the twolarge rockshelters we excavated in three seasons from 1993 through 1995.

The study area extends northward from the slopes of the Mukogodo Hills outinto the inland basins of the Tol and Kipsing rivers on the upper Ewaso Ng’iroplains. Viewed from above, much of the study area appears to be an alluvial fan,that is, a gently sloping deposit of water lain sediment that spreads out fan-like onthe basin floor from an apex in a mountain valley to the south. The gradient of thisfan is between approximately 3 and 8%. The fan that constitutes the study area ispart of the larger Mukogodo Hills bajada, a broad, gently inclined detrital surfacethat formed at the base of the mountain through the lateral coalescence of a seriesof alluvial fans laid down on the upper Ewaso Ng’iro plains by runoff issuingfrom the Mukogodo Hills. The alluvial sediments which make up this bajada areexposed in the deeper channel banks of the tributaries of the upper Ewaso Ng’irothat cut through them.

The modern climate in the Mukogodo Hills and upper Ewaso Ng’iro plainsregion, as in much of East Africa, is semiarid in character. The dry season beginsin May and reaches a peak of aridity in August and September. October and earlyNovember mark the transition to the wet season, which is usually in full force bythe end of November. The rains conclude in April. Generally the volume of rainfallis greatest in the first and last months of the rainy season. The limited rainfall datathat have been collected from the vicinity of the study area in Laikipia indicate amean annual rainfall of slightly more than 530 mm. Temperature in the study areais quite uniform; the yearly daily maximum averages 25.7◦C in the highlands and32.4◦C in the lowland plains.

SEQUENCE OF ALLUVIAL DEPOSITION IN THE STUDY AREA

In the course of our field research, we have excavated, recorded, described,and partially dated 11 stratigraphic profiles though the fan alluvium exposed in thechannel banks of the Tol and Kipsing rivers (Fig. 2). As a result of these geologicalinvestigations, we have identified five distinct sedimentary units and developed aprovisional alluvial chronology for our study area. Results of these investigationsare reported in full in Pearl (2001) and Pearl and Dickson (2004). A summary ofthe alluvial chronology is provided here.

In stratigraphic order from lowest to highest, the five depositional unitsrecognized in our study area are the Peleta (Qp), the Kipsing (Qk), the Shordika(Qsh), the Seaku (Qsk), and the Tol (Qt) (Fig. 3). Although we do not knowtheir lower age limits as yet, the lower of these two units—the Kipsing and theinterfingering Peleta—are of Pleistocene age. The Peleta unit contains weatheredbasalt cores, flakes, and artifacts that, on formal grounds, are referable to theMiddle Stone Age (ca. 200,000–40,000 bp). Similar basaltic material has been

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Fig. 2. Map showing the locations of the 11 Alluvial stratigraphic profiles and of Shurmai (GnJm1)and Kakwa Lelash (GnJm2) rockshelters in the Tol and Kipsing river catchments, Kenya.

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Fig. 3. Generalized stratigraphic column depicting the relationship of the five quaternary depositionalunits recognized in the 11 alluvial stratigraphic profiles excavated in the Mukogodo Hills and UpperEwaso Ng’iro plains study area, Kenya (units not shown to scale).

recovered from Shurmai Rockshelter (GnJm 1) in a sediment layer dated byluminescence to a minimum of ca. 45,211 ± 5356 bp (Kuehn and Dickson, 1999).Lithic material unambiguously assignable to the preceding Early Stone Age (ESA)(ca. 200,000–2,600,000 bp) has yet to be found in the Peleta Unit.

These data suggest that the bulk of the Peleta sediments began to be depositedno earlier than the late Middle Pleistocene (730,000–130,000 bp) and may havebeen laid down in the Upper Pleistocene epoch (ca. 130,000–10,000 bp). Whateverthe date of their initial formation, both the Peleta and the Kipsing units wereapparently exposed on the surface throughout the Late Quaternary period. ThePeleta unit has yielded radiocarbon ages of 19,940 ± 140 bp, and 37,710 +4200/−2740 bp (Pearl and Dickson, 2004, p. 573). During a period of stability, athick soil formed on the level floodplain surface while weaker soil developmentoccurred on the steeper fan deposits in the Peleta unit. These soils developed over

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a considerable period of time under arid conditions as indicated by its petrocalcichorizon. They thus may be classed as an aridisol. Soil formation was most likelycoincident with the Liki Glaciation recorded in the geology of nearby Mt. Kenya(Mahaney, 1981, 1982, 1984, 1988).

At the end of the Pleistocene, conditions in our study area appear to havegenerally become wetter and warmer. A period of channel incision occurred in thecentral portions of the river valleys cutting deeply into Peleta alluvium. Erosionresulted in the loss of Peleta alluvium along the valley centers. In many caseserosion was hindered by the petrocalcic horizon which was more resistant thanthe overlying soil horizons. Deposition ensued, reburying the Peleta soil under theShordika alluvium. The Shordika alluvium aggraded between 13,000 and 8500 bp.When the Shordika unit stabilized, a soil, dated to 8470 ± 350 bp, formed on itssurface (Pearl and Dickson, 2004, p. 574).

During the mid-Holocene, another major episode of floodplain aggradationoccurred and the Seaku alluvium was deposited. A radiocarbon age from the centerof this unit indicates that deposition was well under way by about 1390 ± 95 bp(Pearl and Dickson, 2004, p. 575). A thick, dark, soil horizon with highly organiccontent formed on its surface. Similar soils are found to form today in savannaenvironments.

The Shordika unit was followed by the Tol unit, the principal active surfaceof deposition in the study area. The Tol alluvium is characterized by laminatedsediments formed during recent floods. No archaeological sites have been foundburied in the Tol alluvium. A radiocarbon age of 405 ± 90 bp on charcoal in thesesediments attests to its recent age (Kuehn et al., 1996).

SEQUENCE OF ARCHAEOLOGICAL OCCUPATIONIN THE STUDY AREA

Absolute dating and the analysis of lithic and ceramic materials recoveredfrom the two excavated rockshelters have demonstrated that this region was heavilyutilized by at least the African MSA and perhaps earlier. Occupations referable toLSA, Pastoral Neolithic, Iron-Using, and Recent or Mukogodo periods are alsofound there (Dickson and Gang, 2002; Gang, 1997, 2001; Mutundu, 1999).

Middle Stone Age

The archaeological period known as MSA is generally considered to beginsome time between ca. ∼300,000 and 200,000 bp and to extend over a vastblock of time until ca. 40,000 bp (Ambrose, 2001, p. 1751; Robertshaw, 1995,p. 60). While the formal archaeological record of MSA in East Africa is fairly

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well documented, interpreting this record is one of the more contested topics incontemporary paleoanthropological research.

MSA is distinguished from ESA by (1) the appearance of diverse lithic toolk-its and (2) the rise of clearly identifiable regional variations in style and technol-ogy. These trends suggest that MSA witnesses the emergence of cultural traditionsand culture areas (Clark, 1988). These diverse lithic toolkits are often the prod-uct of prepared core technology. This technology produced numerous specializedblades, backed-blades, uniform triangular/flakes, Levallois flakes, and formal coretool types (Ambrose, 2001, p. 1751; Clark, 1970, p. 124; McBrearty and Brooks,2000, p. 495). Also characteristic is the replacement of the large cutting tools, suchas the hand axes and cleavers that characterized ESA, with core axes and picks.This is particularly evident at Kalambo Falls in Zambia, where ESA and MSA as-semblages are stratified (Clark and Kleindienst, 1974; Sheppard and Kleindienst,1996). These core axes and picks come to characterize the Sangoan industry ofMSA. At Muguruk in western Kenya, Sangoan tools are found stratified beneathother more typical MSA tools (McBrearty, 1988). Robertshaw (1995) concludes,therefore, that the Sangoan industry is the formal intermediary between ESA andMSA.

Excavations at Shurmai Rockshelter (GnJm 1) in the study area have furtherelucidated the technology of MSA knappers (Gang, 1997, 2001). The collectionof tools at Shurmai Rockshelter was dominated by backed and unbacked bladesand flakes, denticulated flakes, and scrapers. Cores from Shurmai Rockshelter aregenerally specialized for flake production. The lowest occupation of the ShurmaiRockshelter clearly delineated beneath a stratigraphic disconformity, producedrelatively crude lithics of fine-grained basalt. An infrared-stimulated lumines-cence measurement of feldspar grains yielded a conservative minimum age of45,211 ± 5,356 bp for the overlying lithostratigraphic unit (Kuehn and Dickson,1999, p. 72).

Later Stone Age

LSA in East Africa is marked by important changes in the archaeologicalrecord. The characteristic MSA technique of manufacturing stone tools on Lev-allois flakes removed from prepared cores disappears in LSA. In place of thistechnique, flakes removed from plain platform cores and then broken to formmicroliths become the norm. Commonly, LSA microliths are small and have been“backed” or blunted on one side, but this is by no means always so (Ambrose,2002, p. 9). LSA also witnesses a substantial increase in the diversity and stan-dardization of artifact types and acceleration in the rate of formal change inthese types through time (Klein, 1999, p. 589). At the same time, numerous toolsmade of bone appear in the archeological record of LSA together with evidence

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of artistic activity, ritualized burials, and jewelry made from bone, shell, andivory.

The transition from MSA to LSA in East Africa is commonly thought tohave begun ca. 40,000 bp and continued there, in a gradual and piecemeal fashion,over the next 20,000 years or so (Robertshaw, 1995, pp. 60–61). Evidence ofthe sluggish pace of this technological transition appears, for example, at siteslike Muguruk (McBrearty, 1988) and Shurmai Rockshelter (Gang, 1997, 2001).However, the 40,000 year beginning date for LSA has been established chiefly bymeans of the direct or Geiger counting method of radiocarbon dating rather thanby accelerator mass spectrometry. Unfortunately, radiocarbon by direct countingis near the edge of its effective range when dating material 40,000 years andolder. Therefore, radiocarbon dates of 40,000 years returned by this method arereally minimum ages which may, in fact, be much earlier. Dates established forearly LSA occupations by techniques other than radiocarbon offer support for thisobservation. For example, Ambrose (1980) notes that obsidian hydration datesfrom Enkapune ya Muto in the central Rift Valley indicate that the transition fromMSA began there earlier than 46,000 bp. At Mumba Rockshelter in Tanzania,amino acid racemization put the age of LSA component at about 45,000 bpwhile the uranium series dating method returned ages closer to 65,000 bp for it(Brooks, 1996; Hare et al., 1993). These and other dates have led many scholars tohypothesize that LSA begins significantly earlier in Africa than has been generallysupposed and far earlier than does the comparable Upper Paleolithic period inEurope.

The chronological problem is not the only interpretive difficulty surroundingthe MSA/LSA transition. Scholars also disagree as to the significance of thepronounced differences between MSA and LSA archaeological components. Onone hand, many paleoanthropologists consider the transition to reflect a substantiveevolutionary transformation during which human behavior moved from “archaic”to more “modern” form. Some go so far as to assert that the emergence of LSAin Africa represents the first appearance of anatomically modern Homo sapienssapiens in the archaeological record. Such an appearance is compatible with themitochondrial DNA evidence that suggests a common ancestry for all modernhumanity emerging in Africa no more than about 200,000 years ago (Cann et al.,1987; Vigilant et al., 1991). For archaeologists of this persuasion, biologicalevolution, not merely cultural change, is afoot in LSA, and they refer to this changeas “the human revolution” (Clark, 1992; Mellars and Stringer, 1989). Also calledthe replacement theory, this model suggests that biologically and behaviorallydistinct humans originated in Africa and later migrated out to replace the morearchaic hominids then inhabiting the earth (Stringer and Andrew, 1988).

A second school of paleoanthropologists rejects this interpretation of LSA,however. McBrearty and Brooks (2000) have made a strong case for a muchearlier beginning for the cultural transition in Africa that supposedly signals the

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“human revolution,” and they suggest that the transition was more gradual and less“revolutionary” than previously thought. This debate seems to have been promptedinitially by the discovery of finely worked bone tools in an extraordinarily earlycontext along the Upper Semliki river in the Western Rift Valley of the Republic ofCongo (Brooks et al., 1995; Yellen et al., 1995). The appearance of finely workedbone artifacts is commonly taken as a key hallmark of the “modern” human be-havior characteristics of LSA, and the sites that contain them, dated by C14, havegenerally been found to be younger than 40,000 years bp. However, McBrearty andBrooks (2000, p. 490) consider radiocarbon dates in the 40,000-bp year time rangeas “infinite,” rather than precise, and therefore advance the hypothesis that Africanbone tool sites that have been classed as LSA on the basis of direct radiocarbondates may in fact be much older. For this reason, a variety of alternative archaeo-metric techniques were employed to date the Upper Semliki river site includingelectron spin resonance, thermoluminescence, optically stimulated luminencence,uranium series dating, and amino acid racemization. These techniques returned asuite of dates older than 89 +22/−15 thousand years bp. The apparent early datesof these tools, coupled with their advanced nature, is an anomaly. If these datesand their interpretations are correct, modern behavior began in Africa much earlierthan anywhere elsewhere in the world (cf. Kuhn and Stiner, 1998; Marshack, 1990;Shea, 2003). Such a conclusion would force a substantial revision in our currentview of Old Stone Age prehistory. However, one site is never sufficient to occasionsuch an interpretive revolution. Before the question can be resolved, the findingsfrom the Semliki River site must be replicated at MSA sites elsewhere in Africa.Perhaps this has happened already. Henshilwood et al. (2002) report the recoveryat Blombos Cave in South Africa of two abstract representations engraved on apiece of red ochre recovered from an MSA layer dated to 70,000 years ago (butcf. Bullington and Leigh, 2002, p. 468).

Middle and Later Stone Age at Shurmai and Kakwa Lelash Rockshelters

While by no means able to resolve this question, our work at the Shurmaiand Kakwa Lelash rockshelters perhaps offers some insights into the transitionfrom MSA to LSA in East Africa. These two sites were test-excavated during theearly 1990s (Kuehn and Dickson, 1999). Shurmai Rockshelter (GnJm 1) produced4782 stone artifacts and was occupied during both MSA and LSA. Kakwa Lelash(GnJm 2) yielded 7862 stone artifacts and appears to have been occupied no earlierthan LSA. All of these lithic materials received a detailed analysis (Gang, 1997,2001). At both sites, the occupation ranges from the end of MSA into LSA.

The area in which the two shelters are located is rich in quartz and volcanicrocks including basalt, granite, gneiss, and schist. Unfortunately, all of theselocally available types of rocks make very poor raw materials for stone tool

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making. Excavations revealed that the inhabitants of the two sites procured higherquality raw materials like chert and obsidian from more remote sources. For avariety of geological reasons, we suspect that such sources are very likely locatedno closer than 10 and no farther than 50 km from the two sites (Gang, 2001, pp. 16–17). The chert recovered from these two sites was considered to be “nonlocal” inorigin. The nearest known obsidian source is located on Mount Kenya about 70 kmfrom the two sites (Merrick and Brown, 1984, pp. 129–135). Therefore, obsidianrecovered at Shurmai and Kakwa Lelash rockshelters can be considered to be“exotic.”

This classification was used to compare the raw material procurement strate-gies of the Middle and Later Stone Ages at the two sites. The number of stone tools,flakes, and cores made of local, nonlocal, and exotic raw materials at the sites weretallied. Chi-square analysis of these tallies indicates that distribution of the threeraw material types in LSA occupations at Shurmai and Kakwa Lelash rocksheltersis statistically identical and that the raw material distribution in the MSA occupa-tion at Shurmai Rockshelter is distinctly different from both LSA occupations. Thiscomparison suggests that raw materials were procured quite differently by MSAand LSA occupants of the two sites. MSA occupants of the Shurmai Rockshelterappear to have relied almost entirely on local basalt and quartz despite the lowquality of such raw material for flint knapping. Although the LSA people continuedto use local basalt and quartz, they appear to have relied just as heavily on nonlocalchert and, to a much lesser extent, on exotic obsidian (Dickson and Gang, 2002,pp. 11–13).

In addition to differences in the types of raw materials preferred, thereare also apparent differences in the way MSA and LSA knappers transportedthese raw materials to their sites. The amount of cortex on lithic material fromthe MSA occupation at Shurmai Rockshelter suggests that their locally avail-able raw materials were taken directly to the site as nodules and were not firstroughed out at their source. In contrast, the lower quantity of cortex on lithicmaterials in the two LSA occupations suggests the opposite-LSA knappers ap-parently roughed out their raw material into blanks before transporting it to thesite. Of course, such behavior reflects the effect of differential “transportationcosts” and simple least-effort calculations. MSA raw materials had only a shortdistance to be carried, while the distance traveled to obtain the nonlocal and ex-otic materials preferred during LSA was substantial (Dickson and Gang, 2002,p. 14).

The small amount of nonlocal and exotic lithic materials recovered from theMSA component at the Shurmai Rockshelter suggests that the MSA knappersprobably did not procure nonlocal and exotic raw material in a systematic manner.Rather, it seems most likely that the MSA occupants of Shurmai Rockshelterobtained high-quality raw materials more or less inadvertently while hunting,collecting, or engaging in seasonal movements. On the other hand, since nonlocal

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and exotic raw materials constitute over 50% of the lithics recovered in the LSAcomponents at both Shurmai and Kakwa Lelash rockshelters, it would appear thatLSA knappers did in fact procure high-quality lithic raw materials in an intentionaland systematic manner. In Binford’s (1979, pp. 259–261, 1989, pp. 19–25) terms,the raw material procurement strategy of the MSA peoples appears to have been“embedded,” and that of LSA people “curated” (cf. Conard, 2001a,b; Odell, 1996;see also Ambrose and Lorenz, 1990, for an application of this approach to MSAin South Africa).

Thus, it would seem that, as compared to their MSA predecessors, the LSAinhabitants of our two sites gave greater consideration to the quality of theirraw materials, preferred to use high-quality raw materials for tool manufacture,made a systematic effort to acquire such materials, and attempted to minimize the“cost” or effort of transporting these raw materials to their occupation sites. Suchacquisition and manufacturing strategies suggest at least two additional behavioraldifferences between the knappers of the two periods. First, compared to the peopleswho occupied Shurmai Rockshelter during MSA, the LSA peoples probably hadbetter information about areas beyond their own immediate territory or had bettertrade connections with surrounding peoples or both. Second, it seems probablethat the people of LSA had higher performance requirements for their tools thandid their MSA predecessors.

Both LSA and MSA knappers at the two sites used the same primary tech-nique for removing flakes for tool making—direct, hard hammer percussion.Neither MSA nor LSA knappers made use of the Levallois technique. Despitethese technical similarities, LSA knappers produced flakes that were shorter, thin-ner, and more varied in shape than those of MSA. Correspondingly, the averagesize of LSA cores is also smaller. At the same time, the cores recovered fromthe LSA occupations are more apt to be “exhausted” than those from the MSAoccupation. An exhausted core is one that has been used so thoroughly that vir-tually no more flakes can be removed from it. This exhaustion may be due tothe relative scarcity of cores of nonlocal material. Their value must have in-duced LSA knappers to use them “down to the nub” before reluctantly discardingthem.

There are also a number of stylistic contrasts between the lithics of the LSAand the MSA components at the two sites. Core tools such as handaxes or cleaverswere not recovered at either of the sites. In both the MSA and the LSA componentsin the rockshelters, all tools were made on flakes except hammer stones (Gang,2001, p. 49). Beyond this, there are few other stylistic similarities between thecomponents. The MSA tool assemblage from the Shurmai Rockshelter includesblades of irregular or rectangular shape and flake tools including points, dentic-ulates, and naturally backed flake “knives.” Tools in the LSA components at theShurmai and Kakwa Lelash rockshelters consist largely of microlithic bladeletsand small flakes with pronounced use wear. The production of naturally backed

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Site Reconnaissance in the Kipsing and Tol River Watersheds of Central Kenya 165

flake knives and convergent flakes was also low in the LSA components at bothsites. This change probably indicates that the simple, naturally backed flake knifewas replaced during LSA by more sophisticated composite tools made by in-serting microlithic bladelets into wooden handles (Dickson and Gang, 2002,pp. 16–17).

Thus, a comparison of raw material composition, technomorphological char-acteristics and style of the MSA and LSA lithic assemblages from the Shurmaiand Kakwa Lelash rockshelters, strongly suggests that the greater sophistication,systematization, and efficiency evident in the patterns of resource use, tool manu-facture and style in the LSA components at these two Rockshelter sites is consistentwith the view that the human behavior that produced the LSA assemblages at thetwo sites was in some sense more “modern” than that evident in the material config-uration in the MSA occupation at Shurmai Rockshelter. Results of the work at theShurmai and Kakwa Lelash rockshelters does not falsify either of the conflictinghypotheses. However, it is consistent with the older view that the origins of modernhuman behavior are to be found in the Later, rather than the Middle, Stone Age inAfrica.

Pastoral Neolithic Period

The earliest form of food production in East Africa is not horticulture or agri-culture. Rather it involves the addition of domestic cattle, sheep, and goats to anotherwise foraging economy of Late Stone Age character and derivation (Marshalland Hildebrand, 2002, pp. 130–131). Livestock husbandry and the presence of ce-ramics in sites of this period have led prehistorians to refer to this tradition asthe “Pastoral Neolithic” (Ambrose, 1980; Bower et al., 1977, p. 119) or, amongFrancophone prehistorians, as le Epipaleolithique avec poterie, pastorale (Barich,1980). Strictly speaking, the term “Neolithic” refers to the traditions of Eurasiacharacterized by pottery and ground stone tool making and settled village agricul-ture. In contrast, the so-called Pastoral Neolithic peoples of eastern Africa seem tohave lived nomadic, rather than sedentary, lives. Further, although they possesseddomesticated cattle, goats, and sheep, there is no clear evidence that Pastoral Ne-olithic peoples raised domesticated plants. This distinctive subsistence system,unmatched in recent herding economies, might be referred to as “carnivorouspastoralism.”

Not only is the nature of the African Pastoral Neolithic life unfamiliar, its ini-tial origins are obscure. As no wild ancestors of domesticated goats and sheep havebeen found in Africa, it is generally concluded that these animals were introducedfrom outside. Very likely, the ultimate ancestral source of these African caprineswas southwestern Asia. On the other hand, the aurochsen or Bos primogenus, thewild ancestor of domestic cattle, were present in late Pleistocene Africa and could

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166 Dickson, Pearl, Gang, Kahinju, and Wandibba

have been the source of the domestic cattle raised by Pastoral Neolithic people. Acontinentwide study of the genetic diversity of African cattle, which was initiated in1994, collected blood samples from some 50 indigenous cattle breeds in contempo-rary Africa. The authors isolated the major genetic trends within these cattle popu-lations using a statistical technique called principal component analysis. This anal-ysis isolated three major geographic clusters of genetic variability, two of whichmatched the genetic makeup of the types of cattle known to have been domesticatedoutside Africa, Bos indicus and Bos taurus from south and southwestern Asia,respectively. The third genetic component isolated in African cattle is derivativeneither of Bos taurus nor of Bos indicus and may, in fact, represent the genetic con-tribution of native wild cattle independently domesticated in Africa (Hanotte et al.,2002).

In any case, the earliest evidence for the appearance of domesticated ani-mal herding in Kenya comes from the Ileret area on the northeastern shore ofLake Turkana in archaeological contexts dating to between 4000 and 5000 bp(Barthelme, 1985; Lynch, 1979; Lynch and Robbins, 1977; Marshall et al., 1984;Robertshaw and Collett, 1983). Although pastoralism was well established innorthern Kenya before that time, it does not appear to have spread into the south-western reaches of Kenya until at least 1000 years later (Robertshaw, 1995).Archaeologists have proposed a number of hypotheses to explain this lag of a mil-lennium or more (Ambrose, 1998; Gifford-Gonzalez, 1998, 2000; Robertshaw,1995). The presence of ceramics referable to the Pastoral Neolithic in the studyarea reflects the presence of this Holocene-age tradition there.

Early Iron-Using Peoples

The Early Iron Age begins in eastern Africa in the Lake Victoria area sometime after about 2500 years bp. Iron metallurgy was apparently introduced intothis region by agricultural, pottery-making peoples assumed by many scholars tohave been Bantu speakers (Phillipson, 1997; but cf. Soper, 1982). But whatever thelanguage of these early iron-using peoples, their smiths produced a range of usefuliron and copper objects such as axes, hoes, arrows, spear points, knives and razorsas well as jewelry rings, bangles, and necklaces. Their farming system evidentlycentered on the raising of drought-resistant native grains like millet, sorghum,and pennisetum and the tending of goats and sheep. Utilizing this system, iron-using farmers expanded westwards from Lake Victoria into central Kenya andsouthwards to Natal by ca. 300 CE (Phillipson, 1985, p. 171). Early iron use in thestudy area is clearly evidenced by the discovery of an iron-making hearth in anarchaeological context near the base of the talus slope below Shurmai Rockshelter.However, this hearth, as well as the artifactual material collected from other sitesin the study area that were roughly contemporary with it, was almost certainly the

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Site Reconnaissance in the Kipsing and Tol River Watersheds of Central Kenya 167

work of iron-using pastoralists who were possessed of ceramics but probably didnot farm.

Recent or Mukogodo Period

Among the most numerous contemporary peoples inhabiting the MukogodoHills region are the Mukogodo. Today, the Mukogodo live as semisedentary peoplewhose subsistence centers on goats, sheep, and cattle supplemented by the keepingof bees. The contemporary Mukogodo speak a dialect of Maa, the language of thecelebrated Maasai and Samburu pastoral peoples who surround them. In addition,they use Maasai styles of dress, ornamentation, and weaponry, live in loaf-shapedhouses made of dung, sticks, and mud, like those of the Maasai, and practice ritualsof circumcision, naming, age-grading, and marriage derived from that tradition. Inshort, the contemporary Mukogodo utilize the essential cultural practices of theirMaasai neighbors and fellow tribesmen. However, this has not always been so.Prior to the 1920s and 1930s, the Mukogodo were a people culturally and linguis-tically entirely distinct from the Maasai. To their Maa-speaking neighbors, theywere il-torrobo (rendered in English as “Dorobo” or, in recent years, “Torrobo”).Dorobo has entered the lexicon of Africanist archaeology and become deeplyembedded as a general term of reference for foraging people who lack cattle.This is unfortunate; the Maa word is a stinging pejorative term roughly equivalentto the American epithets “hillbilly” or “hick” (Cronk, 2002). In those years, theMukogodo gained their livelihood by foraging in the rich, dry tropical cedar-wildolive forest biome that characterizes the uplands of the Mukogodo Hills region.Their subsistence came almost entirely from gathering honey from natural andman-made beehives, ferreting-out burrowing animals, and trapping and huntinghyraxes and various ungulates. In addition, they traded animal skins, giraffe tails,and, occasionally, elephant tusks and rhinoceros horns, to surrounding peoples inexchange for grain and livestock (Cronk, 1989a, p. 59). During this period of theirhistory, the Mukogodo occupied remote caves and rockshelters in the MukogodoForest. The Mukogodo and other “Dorobo” peoples in East Africa are commonlyregarded as little more than impoverished refugees from various pastoralist groups.However, it seems more probable that they are the heirs of the ancient and verysuccessful foraging adaptation that developed in the highland forests of the regionperhaps as early as LSA (cf. Ambrose, 1982, 1986, 1998; Cronk and Dickson,2001).

Whatever their ultimate origins, the Mukogodo began a remarkable socialand cultural transformation in the 1920s and 1930s. It was at this time that theMukogodo abandoned their foraging way of life and assumed the culture of theirMaasai neighbors. The transformation of Mukogodo into Maasai appears to havetaken less than two generations (Cronk, 1989a,b, 2002; Cronk and Leech, 1993).A testament to this cultural change can be found in the study area. At the very top

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168 Dickson, Pearl, Gang, Kahinju, and Wandibba

of the deposits in both Shurmai and Kakwa Lelash rockshelters, butchered hyraxbones, historic ceramics, metal fragments, and limited trade beads have beenrecovered indicating the presence of an historic occupation presumably referableto immediate ancestors of the contemporary Mukogodo (Kuehn and Dickson,1999; Mutundu, 1999).

GOALS AND METHODS OF SITE RECONNAISSANCEIN THE STUDY AREA

The foregoing discussion outlines the archaeological sequence in theMukogodo Hills region as it appeared prior to our site reconnaissance effortsthere in 1996 and 1999. The paucity of our information made it apparent to us atthat time that making sense of the occupations of the Shurmai and Kakwa Lelashrockshelters demanded a clearer understanding of the nature of both human occu-pation and paleoclimate in the region generally. With that recognition in mind, weturned our attention from excavation to site survey and paleoclimatic reconstruc-tion. Reconnaissance in our study area took place over two seasons in 1996 and1999 and was narrowly designed to reach three specific goals:

• to locate and record archaeological sites in the study area and analyze theirsurface lithic and ceramic materials as a means of expanding understandingof the cultural sequence in the Mukogodo Hills region;

• to connect the occupations excavated at Shurmai (GnJm 1) and KakwaLelash (GnJm 2) rockshelter sites with those found in the larger region ofwhich they were a part; and

• to relate the configuration of Quaternary soils, alluvial depositions, andgeomorphology in the study area (a) to the sequence of late Quaternarypaleoclimatic change in the Mukogodo Hills region and (b) to the processesof archaeological site formation operating there.

With these three goals in mind, we laid out a northern and a southern surveytract within the study area that enclosed approximately 24 km2 of territory (Fig. 4).Reconnaissance within these tracts was done in two phases: the first in the dryseason of 1996: the second, 3 years later, during the dry season of 1999.

During both of our field seasons, our teams examined the ground surface inour two survey tracts, using aerial photographs and foot survey. We did this byrunning a series of parallel transects with the survey teams maintaining a “skirmishorder.” That is, we formed a line in which each team member was separated byapproximately 30 m from each other member. These teams then systematicallycrossed and recrossed selected portions of the survey area examining the ground.Upon reaching the boundary of the survey tract, team members moved over ap-proximately 300 m, reestablished 30 m separating them in the skirmish line andbegan a return transect. During the 1996 reconnaissance season, we concentrated

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Site Reconnaissance in the Kipsing and Tol River Watersheds of Central Kenya 169

Fig. 4. Map depicting the two survey tracts in the Mukogodo Hills and Upper Ewaso Ng’iro plainsstudy area, Kenya, and the locations of the 58 sites and 13 spot finds found within them.

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170 Dickson, Pearl, Gang, Kahinju, and Wandibba

our efforts in the northern survey tract along the Kipsing, Seaku, and lower Tolriver valleys. At this time, teams maintained their positions along these transects,using compass bearings. During the 1999 reconnaissance season, we were ableto more closely monitor and record our positions along the transects by satellitetracking, using the Global Positioning System (GPS). During this second season,21 pedestrian transects between 1 and 2 km in length were run over the rough, andsometimes brushy, terrain along the Tol river in both the northern and the southernsurvey tracts (Fig. 4).

Experienced field archaeologists are well aware that the number of siteslocated in a reconnaissance is directly proportional to the intensity with whichthat reconnaissance is conducted (Banning, 2002). This being so, we carefullyconsidered the level of intensity needed to accomplish our three goals in lightof the degree of site visibility on the ground surface. The landscape within theproject area is highly eroded because of heavy, long-term utilization by nomadicpastoralists. With some exceptions, the river catchments support open thorn bushacacia parkland and brushy grassland. Ground cover is, for the most part, limitedand dispersed and ground visibility is high during the dry season. With such highvisibility, we considered 30-m transect intervals (15 m per side) to be sufficientlynarrow to allow each survey team member to view the full transect width. However,even under such conditions of generally high visibility, we readily admit that somesmall or unobtrusive sites were likely missed. As Schiffer and Wells (1982) note,however, it is necessary to survey at impractical intensities in order to discover allsites of low obtrusiveness. We calculate that our transects allowed us to intensivelyexamine the surface of approximately 30% of 24 km2 of territory enclosed withinour survey tracts. In our opinion, this level of intensity was sufficient to meet theresearch goals that we had set for the reconnaissance.

In any case, once a site was located in this manner, it was assigned a fieldinventory number and, where appropriate, its surface remains were sketch mapped.Each site was then fully described on a detailed site form created specifically forour project. In addition, a site report using the official National Museum of Kenya(NMK) form was also filed for each site. The location of each site was determinedby obtaining the exact Universal Transverse Mercator coordinates of its positionfrom a portable GPS. As a backup, each site was also plotted onto a regional fieldmap (1:50,000) using a surveying compass.

At each locus, we made a collection of the artifactual material found on thesurface. In general, the number of artifacts visible on the surface of most sites wasso small that sampling them was not feasible. Under these circumstances, all ofthe archaeological materials visible on the surface were collected. On sites with agreater density of surface material, we attempted to collect a sample representativeof the range of variation present. All samples and artifactual material collected inthe field were taken to the Division of Archaeology of NMK for processing andcuration.

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Site Reconnaissance in the Kipsing and Tol River Watersheds of Central Kenya 171

Our goal in implementing this collection strategy was twofold. First, wesought to assemble a corpus of archaeological material from each site surface inorder to obtain diagnostic tool and pottery types that would provide us with arough indication of the time and duration of the site’s occupation. Second, wesought surface collections sufficient to allow us to compare the functional andmorphological attributes of the artifactual materials from these open sites withthose obtained from the excavations of our two deeply stratified rockshelters,GnJm 1 and GnJm 2.

At NMK, each site was given an official and permanent field number orunique identification code to replace the temporary field inventory number. Thesenumbers were assigned following the Standardized African Site Enumeration Sys-tem (SASES) (Nelson, 1971). It is NMK policy to assign such permanent SASESsite numbers sparingly. The loci in our site corpus that were judged by museumpersonnel to have produced too few surface objects to justify a site number wereclassed as “spot finds” and assigned permanent inventory numbers accordingly.These are indicated in the text with the prefix “0/” with their site number. Althoughthese sites are small, they are, in our judgment, still significant. As such, they areincluded in the overall analysis of land-use patterns. Our site reconnaissance con-centrated on locating archaeological sites exposed on the current land surfacesof the study area. However, preliminary geo-archaeological investigations thereclearly demonstrated that, throughout the late Quaternary period, significant de-position and erosion took place along the flood plains of the Tol and Seaku rivers.We can, therefore, be certain that an unknown, but not inconsiderable, number ofarchaeological sites are buried in these alluvial sediments. Indeed, in previous ex-aminations of the study area, we have discovered isolated lithic finds eroding fromdeeply buried sediments exposed in stream cuts. Locating such sites is difficult andpartly dependent upon luck. Artifact density tends to be light and widely scattered,and some of the floodplain deposits are between 10 and 15 m below the currentland surface. At these densities and depths, manual subsurface testing would beineffective, and the remoteness of the study area makes mechanical subsurfacetesting a logistic impossibility. In our site reconnaissance, we therefore fell backon the strategy of systematically inspecting sediment profiles exposed by erosionin the Tol and Seaku river drainage network. In the course of this inspection, weexamined over 16 linear km of river bank for evidence of subsurface cultural de-posits. The Lenkiteng site (GnJm 38), which we test-excavated in the dry seasonof 2000, was discovered in this manner during the 1999 reconnaissance. We alsoasked knowledgeable local residents about the locations of such exposures as wellas those of rockshelters and other kinds of archaeological sites.

RESULTS OF THE SITE RECONNAISSANCE

During our first field season in 1996, we located and mapped 27 surfacearchaeological sites in our survey tracts before endemic cattle raiding between

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172 Dickson, Pearl, Gang, Kahinju, and Wandibba

Samburu and Somali peoples in the area erupted into open warfare. The widespreadviolence that followed forced us to close our field season prematurely and leavethe study area. Fortunately, we were able to return 2 years later and completethe site reconnaissance over a 6-week period during the dry season of 1999. Atthat time, 32 additional sites and 13 spot finds were recorded, plotted by GPS,and surface collected. This work brings the total number of archaeological locirecorded in the study area to 72: 13 spot finds and 58 sites (Fig. 4).

Almost all of the 72 loci discovered during our reconnaissance were surfacesites that had little or no apparent subsurface expression. Surface collections fromthe 72 loci produced 589 ceramic sherds and 2165 lithic objects. The sherdswere analyzed by Dr Simiyu Wandibba of the Institute of African Studies ofthe National Museums of Kenya. The lithic objects were analyzed in the UnitedStates at the close of the 1999 field season by Dr G.-Young Gang of YeungnamUniversity, Korea, as part of her postdoctoral study at Texas A&M University.Dr Gang conducted the earlier analysis of the lithic assemblage recovered fromthe stratified deposits at Shurmai and Kakwa Lelash rockshelters, and she hasprovided us with an accurate picture of the subtle changes in lithic manufacturingtechniques and raw material use that occurred in the study area over time (Gang,1997, 2001). Similarly, Dr Wandibba’s chronology of ceramic technology in Kenyaprovided us with a means of cross-dating the later period site occupations.

Relative ages were assigned to the occupational components represented atthese sites using “type fossils” identified by Gang in the lithic and Wandibbain the ceramic materials recovered from the site surfaces. That is, temporallysensitive patterns found on certain decorated ceramic wares, as well as temporallydiagnostic lithic tool types and manufacturing techniques, were used to date the sitecomponents. The majority of our 72 loci appear to consist of single occupations.However, multicomponent sites are also present in our corpus. In all, some 88occupational components were recognized on the sites in our two survey tracts.

We are aware, however, that reconstructing the occupational history of asite based on the “type fossils” recovered from its surface is always problematic.Any landscape surface that has been exposed for an extended period of time mayhave been used or occupied at many different times in the past. Further, sheeterosion due to overgrazing in recent times may have removed soil matrices at thesurface and mixed hitherto stratigraphically separate occupations. We, therefore,attempted to check the date of a site’s occupation based on the type fossils itproduced against its position in the sequential alluvial depositional surfaces in thestudy area. While geomorphological location is not a precise indicator of the ageof an archaeological occupation, it does allow us to rule out an ancient age forsites located on younger land forms.

Using ceramic and lithic type fossils together with geomorphological po-sition, we recognized eight types of sites in our site corpus: rockshelter sites,lithic scatters with characteristic MSA and/or LSA materials, lithic and ceramicscatters, ceramic scatters, rock cairns, iron using and smelting sites, and historic

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Site Reconnaissance in the Kipsing and Tol River Watersheds of Central Kenya 173

sites, including some dating to the British colonial and early postindependenceperiod. A list of the sites in our corpus, together with a brief summary of theanalysis of the lithic and ceramic material recovered from each of them, is pre-sented in Table I. The specific location of each site has been omitted from thistable, however. Although the danger seems remote, we have done this to protectthese archaeological sites from illicit digging or disturbance. Authorized partiescan obtain the map coordinates and other locational information for these sitesfrom the site files maintained by the Archaeology Division, National Museums ofKenya, Nairobi.

SUMMARY OF THE ANALYSIS OF THELITHIC SURFACE COLLECTIONS

Of the 2165 lithic objects collected in the study area, 172 were cores, 104tools, 509 flakes, 673 fragments, and 707 pieces of debris. Four types of lithic rawmaterials are represented in the collection: fine-grained basalt, chert, obsidian, andquartz. The majority of lithics in this collection are made of fine-grained basalt,a type of rock abundantly available in the study area (Fig. 5(a) and (b)). Locallyavailable quartz, nonlocal chert, and exotic obsidian (Fig. 6(a) and (b)) were onlylightly represented (Gang, 2001, pp. 29–37). For example, of the 172 cores in thecollection, fully 160 were made of basalt, 8 of chert, and only 2 each of obsidianand quartz.

The cores show a second pattern. Basalt cores were large and lightly usedbefore discard while obsidian and chert cores were small and used to exhaustionbefore discard. Correspondingly, the core/flake index in this population is highfor locally available materials and low for nonlocal and exotic materials. That isto say, a large number of basalt flakes were recovered for each basalt core foundand a small number of chert, obsidian, and quartz flakes were collected for eachcore of those materials recovered.

The analysis of the flakes in the collection also turned up some interestingresults. There are, of course, many different systems for analyzing flakes (forexample, Ahler, 1989; Bradbury and Carr, 1999; Odell, 1989). We chose to adoptthe methods and categories proposed by Sullivan and Rozen (1985) and Shott(1994). Initially the flakes were sorted into two categories depending on whethercortex is present or absent on their dorsal surfaces. Flakes were further subdividedinto one of four categories depending on whether the cortex was estimated tocover less than one-third, about one-third, about two-thirds, or virtually the entiredorsal surface. The location of the cortex on the dorsal surface was also recordedfor each flake. All of this was done because the amount of cortex on a flake is agood proxy indicator of the point in the reduction process at which it was removedfrom its core. Analysis of the basalt flakes in the assemblage revealed that manyflakes have dorsal cortex indicating that they were removed in the early or primary

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174 Dickson, Pearl, Gang, Kahinju, and Wandibba

Tabl

eI.

Ros

ter

of58

Arc

haeo

logi

cal

Site

s,13

Spot

Find

s,an

d86

Occ

upat

iona

lC

ompo

nent

sL

ocat

edin

the

Muk

ogod

oH

ills

and

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was

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g’ir

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ains

,Ken

yaSi

teR

econ

nais

sanc

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rvey

Tra

cts

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ther

With

aSu

mm

ary

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and/

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icM

ater

ials

Rec

over

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omth

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rfac

eof

Eac

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teor

Spot

Find

No.

ofPe

riod

(s)

ofQ

uate

rnar

yco

mpo

nent

soc

cupa

tion

depo

sitio

nal

Cer

amic

Lith

ics

NM

Ksi

teno

.Si

tety

pepr

esen

tre

pres

ente

dun

itFl

akes

Cor

esTo

ols

Deb

ris

sher

ds

GnJ

m7

Lith

icsc

atte

r1

Ear

lyM

SAPe

leta

1624

1059

—G

nJm

8St

one

cair

n1

P.N

eolit

hic?

Pele

ta—

——

——

GnJ

m9

Cer

amic

scat

ter

1Ir

onA

geTo

l—

——

—<

25G

nJm

10C

eram

icsc

atte

r1

Iron

Age

Tol

——

——

<25

GnJ

m11

Cer

amic

scat

ter

1Ir

onA

geTo

l—

——

——

GnJ

m12

aL

ithic

scat

ter

1?M

SAor

LSA

Pele

ta69

153

172

—G

nJm

13L

ithic

scat

ter

1M

SAPe

leta

2610

673

—G

nJm

14L

ithic

scat

ter

1M

SAPe

leta

155

521

—G

nJm

15Ir

onsm

eltin

gsi

te1

Iron

Age

Seak

u—

——

——

GnJ

m16

Lith

icsc

atte

r1

MSA

Kip

sing

257

439

—G

nJm

17St

one

cair

n1

P.N

eolit

hic?

Kip

sing

21

49

—G

nJm

18L

ithic

scat

ter

2M

SA/I

ron

Age

Kip

sing

117

—8

—G

nJm

19L

ithic

scat

ter

1L

SAK

ipsi

ng6

1—

25—

GnJ

m20

Ston

eca

irn

1P.

Neo

lithi

c?K

ipsi

ng—

——

——

GnJ

m21

Ston

eca

irn

1P.

Neo

lithi

c?Pe

leta

——

——

—G

nJm

22L

ithic

scat

ter

1M

SAPe

leta

138

1127

—G

nJm

23L

ithic

scat

ter

4M

SA/L

SA/I

ronA

ge/H

isto

ric

Kip

sing

1512

917

—G

nJm

24St

one

cair

n1

P.N

eolit

hic?

Kip

sing

——

——

—G

nJm

25St

one

cair

ns,l

ithic

scat

ter

2M

SA/P

.Neo

lithi

c?Pe

leta

31

17

—G

nJm

26St

one

cair

n1

P.N

eolit

hic?

Pele

ta—

——

——

GnJ

m27

Cer

amic

scat

ter

1P.

Neo

lithi

cTo

l—

——

—16

3G

nJm

28C

eram

icsc

atte

r1

Iron

Age

Tol

——

——

3G

nJm

29L

ithic

scat

ter

2M

SA/L

SAPe

leta

1—

—11

—G

nJm

30L

ithic

and

cera

mic

scat

ter

2L

SA/P

.Neo

lithi

cPe

leta

——

——

4G

nJm

31L

ithic

scat

ter

1M

SAPe

leta

296

545

—G

nJm

32L

ithic

scat

ter

2M

SA/L

SAPe

leta

181

233

Page 23: Site Reconnaissance in the Kipsing and Tol River Watersheds of Central Kenya: Implications for Middle and Later Stone Age Land-Use Patterns

Site Reconnaissance in the Kipsing and Tol River Watersheds of Central Kenya 175Ta

ble

I.C

ontin

ued

GnJ

m33

Lith

icsc

atte

r1?

?ch

anne

l—

——

2—

GnJ

m34

Lith

icsc

atte

r1

MSA

Kip

sing

—5

413

—G

nJm

35C

eram

icsc

atte

r1

His

tori

cPe

leta

——

——

98G

nJm

36L

ithic

scat

ter

1M

SAPe

leta

171

154

—G

nJm

37L

ithic

scat

ter

1M

SAPe

leta

25

—19

—G

nJm

38B

urie

dlit

hic

scat

ter

1L

SASe

aku

9—

—25

—G

nJm

39C

eram

icsc

atte

r1

Iron

Age

Pele

ta—

——

119

GnJ

m40

Lith

icsc

atte

r1

MSA

chan

nel

——

1—

—G

nJm

41b

Lith

ican

dce

ram

icsc

atte

r1?

?Sh

ordi

ka—

——

—2

GnJ

m42

Lith

icsc

atte

r1

Lat

eM

SAPe

leta

173

139

—G

nJm

43L

ithic

scat

ter

1L

SASh

ordi

ka6

—1

57—

GnJ

m44

Lith

ican

dce

ram

icsc

atte

r3

MSA

/.LSA

/P.N

eolit

hic?

Shor

dika

5—

—13

10G

nJm

46L

ithic

and

cera

mic

scat

ter

1P.

Neo

lithi

c?Sh

ordi

ka—

—1

—34

GnJ

m47

Lith

ican

dce

ram

icsc

atte

r3

MSA

/LSA

/P.N

eolit

hic?

Pele

ta24

—3

8410

GnJ

m48

Smal

lroc

kshe

lter

2L

SA/H

isto

ric

Shor

dika

——

—4

—G

nJm

49L

ithic

and

cera

mic

scat

ter

2L

SA/P

.Neo

lithi

cSh

ordi

ka—

—1

—16

GnJ

m50

Lith

icsc

atte

r1?

?Pe

leta

2—

17

—G

nJm

51L

ithic

scat

ter

1L

ate

MSA

Pele

ta14

2—

22—

GnJ

m52

Cer

amic

scat

ter

1Ir

onA

gePe

leta

——

——

129

GnJ

m53

Mau

–Mau

cam

p1

His

tori

cPe

leta

——

——

—G

nJm

54L

ithic

scat

ter

1M

SAPe

leta

93

12

—G

nJm

55Ir

onsm

eltin

gsi

te1

Iron

Age

Pele

ta—

——

—7

GnJ

m56

Form

erpo

lice

post

1H

isto

ric

Shor

dika

——

——

—G

nJm

57L

ithic

scat

ter

1M

SAPe

leta

2—

17

—G

nJm

58B

urie

dlit

hic

scat

ter

1M

SAPe

leta

22

212

—G

nJm

59L

ithic

scat

ter

1L

SAK

ipsi

ng5

——

10—

GnJ

m60

Lith

icsc

atte

r1?

?K

ipsi

ng1

1—

——

GnJ

m61

Lith

icsc

atte

r1?

?K

ipsi

ng1

——

2—

GnJ

m62

Lith

icsc

atte

r1

MSA

Kip

sing

93

—6

—G

nJm

63C

eram

icsc

atte

r2

Iron

Age

/His

tK

ipsi

ng—

——

—29

GnJ

m64

Lith

icsc

atte

r1

MSA

Kip

sing

7—

—31

—G

nJm

65L

ithic

scat

ter

1M

SAK

ipsi

ng3

—1

4—

GnJ

m0/

10Is

olat

edlit

hic

flake

1??

Pele

ta1

——

——

Page 24: Site Reconnaissance in the Kipsing and Tol River Watersheds of Central Kenya: Implications for Middle and Later Stone Age Land-Use Patterns

176 Dickson, Pearl, Gang, Kahinju, and Wandibba

Tabl

eI.

Con

tinue

d

No.

ofPe

riod

(s)

ofQ

uate

rnar

yco

mpo

nent

soc

cupa

tion

depo

sitio

nal

Cer

amic

Lith

ics

NM

Ksi

teno

.Si

tety

pepr

esen

tre

pres

ente

dun

itFl

akes

Cor

esTo

ols

Deb

ris

sher

ds

GnJ

m0/

11Is

olat

edlit

hic

flake

1??

chan

nel

1—

——

—G

nJm

0/12

Lith

icsc

atte

r1?

?ch

anne

l3

1—

2—

GnJ

m0/

13C

eram

icsc

atte

r1

Iron

Age

Pele

ta—

——

—5

GnJ

m0/

14C

eram

icsc

atte

r1

Iron

Age

Shor

dika

——

——

32G

nJm

0/15

Isol

ated

lithi

cfla

ke1?

?Sh

ordi

ka—

——

1—

GnJ

m0/

16L

ithic

scat

ter

1??

Pele

ta—

11

——

GnJ

m0/

17L

ithic

scat

ter

1??

chan

nel

11

14

—G

nJm

0/18

Lith

ican

dce

ram

icsc

atte

r1

LSA

Shor

dika

——

—1

3G

nJm

0/19

Cer

amic

scat

ter

1Ir

onA

geSh

ordi

ka—

——

—8

GnJ

m0/

20C

eram

icsc

atte

r1

Iron

Age

Kip

sing

——

——

1G

nJm

0/21

Cer

amic

scat

ter

1Ir

onA

geSh

ordi

ka—

——

—16

GnJ

m0/

22Is

olat

edlit

hic

flake

1??

chan

nel

1—

——

aB

ecau

seof

unce

rtai

nty

rega

rdin

gth

eir

peri

ods

ofoc

cupa

tion,

site

sG

nJm

12,3

3,40

,50,

60,6

1,an

dsp

otfin

dsG

nJm

0/10

,0/1

1,0/

12,0

/15,

0/16

,0/1

7,an

d0/

22ar

eno

tinc

lude

din

the

tabu

latio

nspr

esen

ted

inTa

ble

II.

bT

helit

hic

colle

ctio

nm

ade

onG

nJm

41ca

nnot

belo

cate

d.T

here

fore

,the

site

isno

tinc

lude

din

the

tabu

latio

nspr

esen

ted

inTa

ble

II

Page 25: Site Reconnaissance in the Kipsing and Tol River Watersheds of Central Kenya: Implications for Middle and Later Stone Age Land-Use Patterns

Site Reconnaissance in the Kipsing and Tol River Watersheds of Central Kenya 177

Fig. 5. Examples of MSA basalt flakes from the site of GnJm 18: (a) ventral and (b) dorsal views.

Page 26: Site Reconnaissance in the Kipsing and Tol River Watersheds of Central Kenya: Implications for Middle and Later Stone Age Land-Use Patterns

178 Dickson, Pearl, Gang, Kahinju, and Wandibba

Fig. 6. Examples of LSA Chert and Obsidian flakes from the site of GnJm 47: (a) ventral and(b) dorsal views.

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Site Reconnaissance in the Kipsing and Tol River Watersheds of Central Kenya 179

stage of core reduction. Further, it was found that the basalt flakes were generallylarge in size and produced by hard hammer percussion techniques with increasedplatform thickness.

Expedient and formal stone tools were also recovered from many of thesites in the survey tracts. The tool assemblage contains borers, hammerstones,denticulates, scrapers, knives, and choppers. These tools are made on basalt coresand on flakes of various material in roughly equal numbers. In all, 52 tools made oncores and 47 made on flakes were recovered. Both the size and crudeness of thesetools suggest that, in general, they were used in the performance of heavy-dutytasks such as chopping, sawing, hammering, or boring and other demanding andsometimes percussive work at these open sites.

SUMMARY OF THE ANALYSIS OF THECERAMIC SURFACE COLLECTIONS

Ceramic sherds were collected from the surface of 19 of the sites located inthe study area. The density of ceramic remains on these sites varied markedly;163 sherds were collected from the surface of site GnJm27 while site GnJm41produced only two specimens. The ceramics collected from the surface of the sitesin the study area corpus totaled 589 sherds. Of these 549 were body sherds, 28were rim sherds, 6 were neck sherds and fragments, and the remaining 6 wereeither handle fragments or stumps. Specimens were examined for their shape,decoration, and fabric. As used in ceramic studies, fabric is a composite attributewhich includes color, hardness, paste, and texture. Of major concern in this study,however, was paste and texture.

No complete vessels were found, and the fragmentary condition of the sherdsmade it difficult to determine the range of vessel forms represented in the assem-blage with any precision. However, the neck sherds and neck fragments recoveredwhich, taken in sum, indicate that a minimum of five different ceramic vesselforms were used over time in the study area: (1) necked vessels, (2) globular orbeaker-like pots, (3) pots with restricted orifices, (4) pots with rounded rims, and(5) pots with square rims. The orifices of these last two forms were apparentlyunrestricted.

Only 36 (or 5.3%) of the 589 sherds in our corpus of specimens exhibitedany decoration. The largest number of decorated sherds, some 13 specimens inall, were recovered at site GnJm 63. Five of these specimens (with two of themconjoining) were decorated with grooved lines and delineated with comp-stampimpressions. One other body sherd carried comp-stamp impressions and threedepressions forming a wide v-shape. A row of comp-stamp impressions was alsoobserved on two other body sherds. In addition, one body sherd had a ridge withsuperimposed impressions.

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180 Dickson, Pearl, Gang, Kahinju, and Wandibba

In East Africa, as in other regions of the world, decorative style is usu-ally the best source of information about the date of manufacture of a ce-ramic ware. Although this is true in sherds recovered from the sites in oursurvey, the temporal information provided by the decorated specimens in ourcorpus is nonetheless unremarkable. First, the presence of beveled rims at siteGnJm 63 would appear to suggest affinities with Gatung’ang’a iron age pottery(Siiriainen, 1971). The Gantung’ang’a site, located about 115 km southwest ofthe study area, has been dated to around 600–800 bp. Second, a globular/beaker-like vessel with the milled neck lip from site GnJm 27 probably dates to thePastoral Neolithic period as do the sherds decorated with comp-stamp impres-sions from sites GnJm 30 and 49. Finally, two decorative techniques, the ridgewith superimposed impressions on the sherds recovered at site GnJm 63 andthe twisted string roulettes motifs from site GnJm 35, are possibly of a morerecent, post-Neolithic age as they are similar to sherds found in the recent oc-cupations of numerous Kenyan sites (Robertshaw et al., 1990; Siiriainen, 1971,1976).

SITE AND SETTLEMENT PATTERNING IN THE STUDY AREA

Analysis of the artifactual material recovered from the surfaces of the 72loci indicates that occupation had begun in the study area at least by MSA andcontinued in the subsequent LSA, Pastoral Neolithic, Iron-using, and historicperiods. Concurrent analysis of the array of stratigraphic profiles cut and recordedin the alluvium of the study area revealed that these occupations took place overtime on five sequential depositional surfaces there. Two of these depositional units,the Peleta and Kipsing, are of Pleistocene age and appear to have been exposed asrelict surfaces at various places in the study area throughout the Late Quaternaryperiod. The third unit, the Shordika, is evidently of Late Pleistocene/Holocene age,while the Seaku and Tol surfaces formed in the late Holocene epoch. Analysis ofthese archaeological and geological data sets has given us insight into the way inwhich Stone Age peoples utilized the landscape in this hitherto poorly known partof eastern Africa.

The alluvial stratigraphic unit associated with each of our 58 sites and 13spot finds was identified and recorded. Table II displays the distribution of sites inthe study area by depositional unit and period of occupation. The data expressedin this chart leads to the following generalizations:

• MSA occupation sites are twice as abundant in the study area as are thosereferable to LSA or any of the four later periods (MSA is also the longestof the five periods represented in the archaeological record of the studyarea);

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Site Reconnaissance in the Kipsing and Tol River Watersheds of Central Kenya 181

Table II. Surface Archaeological Site Components Located in the Mukogodo Hills and UpperEwaso Ng’iro Plains, Kenya Site Reconnaissance Survey Tracts

Quaternary depositional unitsTotal no. of

Tol Seaku Shordika Kipsing Peleta site componentsOccupation periods (Qt) (Qsk) (Qsh) (Qk) (Qp) by period

Historic 0 0 2 2 2 6Iron Age 4 1 3 4 4 16Pastoral Neolithic 1 0 4 3 6 14LSA 0 1 5 3 4 13MSA 0 0 1 7 16 24Total no. of 5 2 15 19 32 73a

site componentsby occupation

Note. Sites are plotted by the periods of their occupation and the Quaternary depositional units on orin which they are located.aEighty-six components were identified on the 58 sites located in the study area transects. However,the period of occupation and/or the Quaternary depositional unit of 13 of these components couldnot be determined (see footnotes in Table I). Consequently, the total number of site componentslisted in this table is 73.

• MSA and LSA occupations occur on both the Peleta and the KipsingPleistocene surfaces but are more abundant on the stratigraphically lowerPeleta unit than on the higher Kipsing;

• only one MSA site was found on the Shordika or younger depositionalunits, even though material of this age might have occurred there insecondary context;

• More than one-third of the LSA sites in our corpus occurs on the Shordikasurface;

• MSA sites are present in roughly the same density in both the north andsouth survey tracts in the study area; and

• LSA sites are abundant in the southern survey tract at the edge of theMukogodo foothills but are conspicuously absent from the northern tractalong the Tol River.

The fact that occupations identified as MSA in age are most abundant on thePeleta and Kipsing, the stratigraphically oldest depositional units, and absent onthe stratigraphically younger units, suggests that we have correctly assessed therelative age of these lithics using lithic “type fossils.” The location of these putativeLSA sites on the stratigraphically higher Shordika and Seaku depositional units, aswell as on the lower Peleta and Kipsing units, is consistent with our expectationsabout their relative age.

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182 Dickson, Pearl, Gang, Kahinju, and Wandibba

MSA and LSA Site Distributions

Thus, reconnaissance revealed an unexpected aspect in the distribution ofsites. While MSA sites are more or less uniformly distributed throughout thestudy area, LSA sites are concentrated at its southern end (Fig. 7). It is our re-search hypothesis that the difference in the distribution of MSA and LSA sitesreflects distinctive patterns of technology, settlement, and land use practiced duringthe two periods. However, it might be due to the operation of natural formationprocesses like alluvial deposition or simply be an error in our sampling of thepopulation of sites in the study area.

We tentatively reject the hypothesis that natural formation processes operat-ing on the alluvial fan in the study area explain the difference in MSA and LSA sitedistribution. The Peleta and Kipsing land surfaces appear to have been exposedon the surface at both the northern and southern ends of the study area during theLate Quaternary period. Therefore, both surfaces would have been available foruse during LSA. Rejecting the hypothesis that the difference is due to samplingerror is more difficult. In fact, only additional site reconnaissance on a larger scalewould resolve the question. Nonetheless, we are confident that the thoroughnessof our survey methods makes it unlikely that we missed a significant number ofsurface archaeological sites. This leaves us with the hypothesis that the differencebetween the locations of MSA and LSA sites reflects actual differences in behaviorbetween those two periods.

MSA and LSA Land Use

To assess the hypotheses that our site survey has revealed genuine differencesbetween MSA and LSA use of the land, it is necessary to compare the lithicassemblages from our two Rockshelter sites with those collected from the opensites in the survey transects. This comparison reveals that the pattern of coreand flake manufacture in the MSA and the LSA open sites generally duplicatesthat found in the MSA and LSA components at the Shurmai and Kakwa Lelashrockshelters.

• In both open and Rockshelter settings, basalt cores recovered are large andlightly used before discard while obsidian and chert cores, although onlylightly represented in the collections, are small and flaked to exhaustionbefore discard.

• Large basalt flakes, essentially identical to those found in the MSA com-ponent at Shurmai Rockshelter, were recovered from the open sites. Flakesin both contexts are large, were produced by hard hammer percussion, andgenerally exhibit dorsal cortex and thick striking platforms.

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Site Reconnaissance in the Kipsing and Tol River Watersheds of Central Kenya 183

Fig. 7. Map depicting the locations of sites with MSA and LSA components in the two survey tractsin the Mukogodo Hills and Upper Ewaso Ng’iro plains, Kenya.

Page 32: Site Reconnaissance in the Kipsing and Tol River Watersheds of Central Kenya: Implications for Middle and Later Stone Age Land-Use Patterns

184 Dickson, Pearl, Gang, Kahinju, and Wandibba

• From a functional standpoint, the MSA tool assemblages in both settingsare identical. The corpus of these basalt tools from the open and rock-shelter sites contains borers, hammerstones, denticulates, scrapers, knives,and choppers. The size and crudeness of these implements suggests theywere used in the performance of such heavy-duty and percussive tasks aschopping, cutting, sawing, hammering, or boring.

However, the pattern of expedient and formal tool making observed in theopen sites contrasts markedly with the patterns found in MSA and the LSAcomponents in the two rockshelters.

• In the MSA and the LSA components at the Shurmai Rockshelter and theLSA component at Kakwa Lelash Rockshelter, both expedient and formaltools were made almost entirely on flakes. Further, these flakes were madeof a variety of raw materials including basalt, quartz, chert, and obsidian.

• In the MSA and the LSA open sites, expedient and formal tools werefashioned on cores and flakes in roughly equal numbers. Further, the over-whelmingly majority of these tools were made of basalt, and on the basisof formal criteria, appear to date to MSA.

The lithic assemblages from the MSA component at Shurmai Rockshelterand from the numerous MSA open sites like GnJm 7 and GnJm 23 indicate that,in both settings, MSA people employed locally available basalt raw materials inthe manufacture of generalized toolkits. However, they manufactured these toolsslightly differently in the two settings; in the open sites, expedient and formal toolswere made on both cores and flakes while in the MSA component in ShurmaiRockshelter, only flakes were used in tool manufacture.

There are at least two possible explanations for this marked difference inthe ratio of core to flake tools in the tool arrays from these two kinds of sites.On one hand, this contrast may indicate that (1) different kinds of activities wereperformed at the two kinds of sites or (2) the MSA stone knappers were making“least effort” calculations in their raw material usage. Knappers who made toolsat the open site were no doubt close to the sources of the basalt cobbles theyused as their raw materials. Thus, in the open settings, there was little reasonto conserve raw material first by reducing a single basalt core into a number offlakes before fashioning tools. Conversely, stone knappers working in the ShurmaiRockshelter found themselves at some distance from their raw material sources.The effort involved in transporting basalt cobbles up into the Rockshelter verylikely encouraged knappers to optimize their use of raw materials by reducingtheir cores to flakes before making tools. Of course, these explanations need notbe mutually exclusive; both may be true.

With the exception of the aforementioned difference, the structure of theMSA lithics from the open sites and the rockshelters was quite similar. This

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Site Reconnaissance in the Kipsing and Tol River Watersheds of Central Kenya 185

suggests that the MSA people were performing the same or very similar activitiesin the open as they were in their Rockshelter encampments. That is, they wereusing the landscape in a broadly uniform fashion throughout the study area.From this, we may hypothesize that the MSA peoples were employing a “patch-choice” foraging strategy. That is, they were opportunistically exploiting theirenvironment by using a location or “patch,” until its resources were depletedand then moving on and applying the same extractive foraging patterns to a newpatch. Such a strategy would mean that any given portion of the catchment areawould have been only intermittently occupied by the MSA people. It would alsolikely produce a settlement pattern in which the sites are widely distributed overthe catchment area and characterized by a more or less uniform array of lithics.This is precisely the pattern of MSA site distribution that we observe in the twosurvey tracts in the study area. The near exclusive reliance placed by the MSAknappers on locally available basalt raw material in tool manufacture suggeststwo more hypotheses about the MSA economy in the study area. First, it suggeststhat the MSA people there acquired their raw lithic materials in a manner thatwas embedded in their basic subsistence schedules. That is, the acquisition ofraw materials was incidental to their food procurement activities, and special tripsto obtain the lithic raw materials they required were not undertaken (cf. Binford,1979). Second, the preference of these MSA knappers for local basalt suggests thatthey had very low, or very generalized, performance requirements for their tools.Perles (1991, pp. 226–227) evaluates raw materials for stone tool making on twodimensions: functional quality and flaking quality. In terms of flaking quality, thelocally available fine-grained basalt ranks very low because it is hard to modify.On the basis of extensive controlled experiments, Deunert (1995, p. 31) concludesthat, compared to flint, basaltic rocks tend to produce rougher, more uneven,fractures. Further knappers are required to hit basalt nodules harder, faster or withheavier hammers than when working with chert or flint. Such procedures reducethe knapper’s accuracy and result in a less controlled manufacturing process. In thecourse of his experiments, Deunert found that flaking accuracy is especially lowwhen basalt nodules are worked on an anvil. Nonetheless, the functional qualityof basalt appears relatively high; experimental data indicates that fine basalt holdsup well in the face of heavy percussive use (Deunert, 1995, pp. 41–45). The MSAknappers appear to have been satisfied with producing generalized tools suitedprimarily for the performance of percussive tasks.

By the LSA period in the Late Pleistocene, however, it appears that these MSAtechnical and land-use strategies had changed markedly. As noted earlier, Dicksonand Gang (2002) provide lithic evidence for behavioral differences between theMSA and the LSA occupants of Shurmai and Kakwa Lelash rockshelters andconclude that, compared to their MSA predecessors, the LSA inhabitants of thetwo Rockshelter sites (1) gave greater consideration to the quality of their rawmaterials and preferred to use high-quality raw materials for tool manufacture,

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186 Dickson, Pearl, Gang, Kahinju, and Wandibba

(2) made systematic efforts to acquire such materials, and (3) sought to minimizethe “costs” of transporting nonlocal and exotic raw materials back to Shurmaiand Kakwa Lelash rockshelters. On the basis of these general inferences from thelithic data, Dickson and Gang (2002, p. 19) conclude that LSA people in the studyarea had better information about areas beyond their own immediate territorythan did their MSA predecessors. Their greater familiarity with their surroundingsimplies that, compared to the peoples who occupied Shurmai Rockshelter duringMSA, the LSA knappers in the study area (1) practiced greater residential mobility(Parry and Kelly, 1987, pp. 303–304) or (2) had larger “extended site territories”or (3) had better trade connections with surrounding peoples (Kusimba, 1999,pp. 186–187). In fact, all three may have been features of the subsistence andsettlement systems that operated in the study area during LSA.

The foregoing inferences suggest that our LSA knappers had a rational setof lithic procurement patterns. Collectively, these patterns constitute what Kuhn(1992) terms “planning and technological provisioning strategies” designed toinsure “the availability of tools in situations where it would not otherwise bepossible to have them.” Our data suggests that the technology of the LSA occupantsof our two sites was, in Binford’s (1979, 1989) terms, a curated one. Or, rather lessgrandly, that, on the continuum from highly organized, curated to poorly organized,expedient technologies, our LSA assemblages rank towards the former, and ourMSA assemblages towards the latter end of this scale.

The distribution of LSA sites within the two survey tracts of the study areaadds a land-use dimension to the Dickson and Gang (2002) sketch of LSA technicalstrategy. Recall that our reconnaissance revealed that, while MSA sites are moreor less uniformly abundant throughout the study area, LSA sites are concentratedat its southern end and largely absent from the north. As noted, this pattern maysimply be the result of sampling error or the fact that LSA people used the areain a manner that is invisible in the archaeological record. However, we cannot atthis time reject the hypothesis that the absence of LSA sites in the northern surveytract reflects real differences in land utilization between the MSA and the LSAperiods.

The observed distribution of LSA sites suggests that people in this periodwere employing what Binford (1980) has referred to as a logistical food-collectingstrategy. This is not to say that they were true collectors in the sense that Binforduses the term. We have not, for example, recovered evidence that they practicedthe sorts of food storage that he considers requisite in this kind of foraging, even atthe excavated Rockshelter sites. However, the observed pattern of archaeologicalsites in our survey areas do suggest centrally organized resource procurement.

The LSA Rockshelter occupations at Shurmai and Kakwa Lelash rocksheltersare distinguishable in content and scale from the other LSA sites, of which noneare so large or have as much interassemblage variability. This may indicate that theLSA people were employing a central-place foraging system wherein they carried

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Site Reconnaissance in the Kipsing and Tol River Watersheds of Central Kenya 187

out the bulk of their archaeologically visible activities at a residential base. Theremaining LSA sites might then represent locations where extractive activities ofone kind or another might have been carried out on a short-term basis. If in factthe LSA people in the study area were practicing logistical foraging, they mightalso have moved from an embedded resource procurement strategy to a directprocurement strategy. This shift to an intensified mode of production very likelypreceded the introduction of pastoralism into the area and may reflect the impactof population growth or ecological change or both.

ACKNOWLEDGMENTS

This research was sponsored by the Office of University Research of TexasA&M University, the Department of General Academics of Texas A&M Universityat Galveston and the Brazos Valley Museum of Natural History, Bryan, Texas.Thanks are due to William Seitz of TAMU Galveston, Thomas Lynch of the BrazosValley Museum of Natural History and George Abungu and Karega-Munene of theNational Museums of Kenya for their enthusiastic support. Lee Cronk of RutgersUniversity and David Carlson and Mary Ann Dickson of Texas A&M read thiswork in manuscript and offered us valuable criticism and helpful suggestions.Jason Barrett reproduced the photographs of our lithics and redrew Figs. 2 and3. Finally, we remain deeply grateful to the staff and students of the KipsingAcademy primary school and to the Mukogodo and Samburu peoples of Laikipiaand Isiolo Districts generally for their kindness, good nature, and hospitality duringour fieldwork in Kenya.

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