Site formation at Kudu Koppie: A late Earlier and Middle Stone Age site in northern Limpopo Province, South Africa

Quaternary International 216 (2010) 151–161

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Site formation at Kudu Koppie: A late Earlier and Middle Stone Age site in northern Limpopo Province, South Africa L. Pollarolo a, c, *, J. Wilkins b, K. Kuman a, c, L. Galletti d a

School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Private Bag 3, WITS 2050 Johannesburg, South Africa Department of Anthropology, University of Toronto, 19 Russell Street, Toronto, ON M5S 2S2, Canada c Institute for Human Evolution, University of the Witwatersrand, Private Bag 3, WITS 2050 Johannesburg, South Africa d APEMA (A Paleontological Eye on Mediterranean Area) Research and Educational Service, Via alla Falconara 34, 90136 Palermo, Italy b

a r t i c l e i n f o

a b s t r a c t

Article history: Available online 6 December 2009

In the Mapungubwe National Park, near the confluence of the Shashe and Limpopo Rivers along South Africa’s northernmost borders with Botswana and Zimbabwe, the site of Kudu Koppie is characterized by three lithologically and archaeologically distinct Stone Age units. From bottom to the top, these units are: (1) the Lower Kudu Koppie Unit (LKKU), which includes large tools such as handaxes, picks and cleavers, characteristic of a late Earlier Stone Age phase; (2) the Middle Kudu Koppie Unit (MKKU), which contains bifacially retouched points characteristic of a Middle Stone Age (MSA) industry; and (3) the Upper Kudu Koppie Unit (UKKU), which has sporadic segments and other tools characteristic of the Later Stone Age (LSA). A refitting and nodule analysis, which matches lithic pieces based on microscopic similarities in colour, texture, and other visible characteristics, demonstrates that site formation processes have caused some vertical displacement of material within, but not between the LKKU and MKKU. Within the national park, the Kudu Koppie sandstone outcrop is unusual in that it has an overhanging structure, which undoubtedly contributed to the initial formation and eventual preservation of the archaeological deposits. This paper presents several lines of evidence indicating that stratigraphic integrity at Kudu Koppie has been preserved and that the three horizons are in primary or near-primary context. Ó 2009 Elsevier Ltd and INQUA. All rights reserved.

1. Introduction Acheulean assemblages are known from many sites in Africa from ca 1.7–0.3 Ma (e.g., Leakey, 1971; Isaac, 1977; Noll, 2000; and see Klein, 2000; Clark, 2001; Kuman, 2007 for reviews). In Africa, the abandonment of the manufacture of handaxes and cleavers and the introduction of points have been dated to the Middle Pleistocene and are used by archaeologists to signal the end of the Acheulean and the commencement of the Middle Stone Age (Grun et al., 1996; Barham, 2001; Tryon and McBrearty, 2002). This development might be related to the appearance of more derived Homo sp., such as those found at Florisbad (South Africa), Singa (Sudan), and Jebel Irhoud (Morocco) (Klein, 1999). Most Acheulean assemblages in southern Africa are found in open-air locations (Kuman, 2007). The few exceptions are Cave of Hearths and the Olieboompoort rockshelter (Mason, 1962, 1988),

* Corresponding author at: School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Private Bag 3, WITS 2050 Johannesburg, South Africa. Tel.: þ27 827291579; fax: þ27 117176578. E-mail address: [email protected] (L. Pollarolo). 1040-6182/$ – see front matter Ó 2009 Elsevier Ltd and INQUA. All rights reserved. doi:10.1016/j.quaint.2009.11.019

the Wonderwerk cave (Malan and Wells, 1943; Beaumont and Vogel, 2006; Chazan et al., 2008) and Montagu Cave (Keller, 1973) in South Africa, and the Zimbabwean sites of Bambata and Pomongwe (Armstrong, 1931; Cooke, 1963). Because the southern African landscape has been subject to substantial erosion (Klein, 2000), the valuable record provided by open-air sites, which form the majority of the Earlier Stone Age, needs to be assessed carefully. Each site requires determination of the degree of primary versus altered depositional context. Moreover, continuous well-dated sedimentary or occupational records across the Acheulean–MSA transition are rare. There are very few sites in northern and southern Africa where both Acheulean and MSA material have been recovered in stratigraphic sequence. At a few sites where they have been, the Acheulean deposits are separated from the MSA by erosional unconformities, suggesting a significant temporal gap (Clark, 1982; Wendorf et al., 1994; Tryon and McBrearty, 2002). Whilst some MSA sites occur along riverbanks, in floodplains, in lake or pan margins, and in spring deposits, much of the archaeological investigation of the MSA has thus far focused on cave sites, which often contain more continuous occupation sequences and faunal remains (Volman, 1984).

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With the intention of documenting the extensive occurrence of Pleistocene Stone Age artefacts in the northernmost part of South Africa, this palaeoarchaeology research team has surveyed the three farms of Samaria, Hackthorne and Machete in the Mapungubwe National Park (Fig. 1). An intensive program of test-pitting (Le Baron, 2007) resulted in the opening of three main excavations at the sites of Hackthorne, Keratic Koppie and Kudu Koppie (Pollarolo, 2004; Kuman et al., 2005a,b; Kempson, 2007; Pollarolo and Kuman, 2009). Of the three sites, Kudu Koppie has yielded the most abundant lithic remains, as well as some bone, seeds, and refitting artefacts, all of which have been preserved within a stratified sequence. Detailed descriptions of the ESA and MSA assemblages are in preparation. The purpose of this paper is to document the stratigraphic context of the Kudu Koppie site.

2. Site setting The Kudu Koppie site (Site Number 2229AB415; 22130 40.500 S 29 200 21.600 E; 604 m a.s.l.) is located in the northern Limpopo Province of South Africa, in a sub-desertic zone with steppic and dry savanna vegetation (Savannah biome) with <500 mm annual rainfall (Bromage and Schrenk, 1999). The vegetation of the area is a typically short, fairly dense growth of shrubby Mopane trees (Colophospermum mopane), and a somewhat sparse and tufted grassveld. The riparian fringe of the Limpopo is a dense vegetation community with a closed canopy, which occurs in the rich alluvial deposits along the river, and limpopo floodplain has allowed for the growth of massive baobab trees (Adansonia digitata).

Fig. 1. Map of the study area immediately south of the Limpopo River showing the location of three sites mentioned in the text, Kudu Koppie (A), Keratic Koppie (B), and Hackthorne (C), and a 3D model of the escarpment.

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The relatively flat landscape is broken up by a number of sandstone outcrops or ‘koppies’ and a 3 km long escarpment about 4 km south of the modern river, orientated northeast–southwest (Fig. 1). The escarpment is the only visible remnant of alluvial terrace sediments created by the Palaeo-Limpopo River. The terrace is composed of a succession of different compact and resistant horizons consisting of calcrete and other cemented deposits (Le Baron, 2007). Where the terrace’s horizons are exposed along road cuts, the crust of calcrete is visible, while some underlying deposits are dorbank, cemented by silica, with up to 30 m of cemented deposit visible (Le Baron, 2007). The extension and the thickness of the terrace are unknown, with the exception of the profiles exposed by road cuts. The terrace is Miocene in age, and its sediments were cemented during an arid period in the late Miocene or early Pliocene (de Wit et al., 2000; Kuman et al., 2005a). During the Plio-Pleistocene the terrace was eroded (de Wit et al., 2000). From an archaeological point of view, this terrace played an important role, yielding large amounts of cobbles that were used throughout the Stone Age occupation of the area for the production of stone tools. Geologically, the northernmost part of South Africa belongs to the Tuli Basin, filled by sedimentary and igneous rocks of the Carboniferous to Middle Jurassic periods that form part of the Karoo Supergroup (Bromage and Schrenk, 1999). The Tuli Basin is composed of four lithostratigraphic units, namely the Basal, Middle and Upper Units, and the Clarens Formation. The latter dominates the geology of the Kudu Koppie area and is composed of Early Jurassic aeolian sandstone (Aldis et al., 1984; Bordy, 2000; Bordy and Catuneanu, 2001). The Clarens Formation forms the local bedrock and all the koppies (sandstone hills) that rise over the flat sand-mantled surface. This sand cover consists mostly of homogenous aeolian sands, based on grain size attributes; two other, temporally distinct aeolian deposits have also been identified (Le Baron, 2007). Within this geomorphological setting sits Kudu Koppie, which is a very large, hilly outcrop of sandstone about 5 km from the modern Limpopo River. 3. Archaeological setting Three sites (Fig. 1) have been excavated in this region of the Limpopo: Kudu Koppie, Hackthorne and Keratic Koppie (Pollarolo, 2004; Kuman et al., 2005a,b; Kempson, 2007; Le Baron, 2007). Hackthorne and Keratic Koppie have only yielded lithic remains, but no bone or seeds as found at Kudu Koppie. Neither Hackthorne nor Keratic Koppie has an LSA component. Both sites were covered by an aeolian sand mantle (Kuman et al., 2005a) dated to the late Pleistocene and Holocene by OSL (Jacobs and Collett, 2005). The area is also well known for the site of Mapungubwe (AD 900–1300), an important Iron Age site in South Africa known for its complex society and structured political organization (Huffman, 2008). At the Hackthorne site, 25  1 m2 were excavated. The site is situated atop the remnant Miocene terrace, approximately 30 m from its northern edge (Kuman et al., 2005a; Le Baron, 2007). The calcretized surface of the terrace buried by younger sands is irregular, having been eroded by humid acid from vegetation, and the sand cover has filled these irregularities and multiple solution pockets, known locally as makondos (Kuman et al., 2005a). The artefacts at Hackthorne are not situated within discrete horizons but are concentrated at the base of the sands, with most lithics recovered from lowest levels in the sand or resting on top of the uppermost calcrete. As the Hackthorne assemblage is overwhelmingly late ESA in character (Kempson, 2007), the context of the tools is thus a lag deposit covered by younger sands that began accumulating in the late Pleistocene

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15.8  1.1 ka (Jacobs and Collett, 2005; Kuman et al., 2005a). This assemblage is composed of 8899 pieces, of this 5848 (66%) are <20 mm, and 3051 (44%) 20 mm, and 34 (1.11%) of the total assemblage are formal tool. The excavation at the Keratic Koppie site is located within 7–8 m of a large sandstone outcrop. A 3 m2 trench perpendicular to the koppie has been excavated, showing excellent preservation of lithics, including abundant small flaking debris and four sets of refitting artefacts (Le Baron, 2007). The small assemblage size, 2092 (70.3%) pieces <20 mm and 883 (29.70%) pieces 20 mm, and the low number of formal tools (1.01%) of the total assemblage are due only to the limited area excavated, as the accumulation is relatively rich (Kempson, 2007; Le Baron, 2007). The artefacts are found in a thin deposit containing sparse ferricrete gravels immediately overlying the sandstone bedrock, buried beneath almost 2 m of sands of late Pleistocene to Holocene age (Le Baron, 2007). As at Hackthorne, the concentration of non-LSA artefacts on the bedrock indicates a deflated lag deposit. LSA lithics are also lacking in the overlying sands, and the assemblage appears to include both ESA and MSA types, suggesting greater mixing than at Hackthorne (Kempson, 2007). Although Keratic Koppie is just some metres away from the koppie, excavations did not yield sandstone clasts or rubble weathered from the koppie. This observation contrasts with what has been observed at Kudu Koppie (see Section 4). Unlike Kudu Koppie, Keratic Koppie does not appear to have a buried talus slope deposit, which is due to the differing physical structure of the outcrop. 4. Kudu Koppie Following three initial test pits at Kudu Koppie by Le Baron in 2003, excavations were begun in 2004 on the southwestern side of the koppie, where artefacts appeared to be densely concentrated in buried talus deposits (Pollarolo, 2004). The main excavation consists of 10  1 m2 squares (including one isolated square, 1S/3W, 3 m west of the main excavation), plus an additional five trenches excavated in the immediate area (Fig. 2). One trench, Test Pit #3 located 20 m away from the koppie to the southwest, was excavated over 2 m2 and reached a maximum depth of 2.30 m to the sandstone bedrock. The squares in the main excavation were worked from 2004 to 2007 and were taken to sandstone bedrock, which is part of the adjacent Clarens Formation outcrop. Sediment analyses and OSL dating of samples from the sand mantle of the area were also undertaken. In order to understand fully the nature of the talus slope deposit, we analysed the lithology of each unit and conducted a refitting and nodule analysis of the recovered artefacts. Figs. 3 and 4 present the stratigraphic profiles of the west and north walls of the main excavation area, respectively. It is clear that three different units are present, but not all three are found in each square. Predictably the talus thins and slopes westwards with greater distance from the koppie. The stratigraphic sequence is described in Sections 4.2–4.5. 4.1. Refitting and nodule analysis A refitting and nodule analysis was conducted to investigate site formation and/or transformation processes at Kudu Koppie (Wilkins, 2008). In this analysis, a sample of approximately 3400 complete flakes, incomplete flakes (with platforms and bulb of percussion preserved), flake fragments (no platform preserved), split flakes and cores from three square units (3S/2E, 3S/3E, and 2S/2E) were sorted according to raw material type. Where possible, matched lithics were refit with each other (Fig. 5). Additionally, several lithics were

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Fig. 2. Kudu Koppie site plan in relation to adjacent koppie (A), photo of Kudu Koppie (B), photo showing main excavation area (C).

matched with each other based on colour, texture, lustre, and grain characteristics (Fig. 5). Because the Kudu Koppie assemblage was produced on a diversity of raw material types, including several quartzite and rhyolite river cobbles that possess very distinct colours, textures, and grain characteristics, it was apparent that certain elements clearly belonged to the same nodule of raw material despite failed attempts to refit the individual pieces. To substantiate this claim, the matched lithics were observed under 10 and 30 magnifications using a light microscope to ensure the lithic composition was identical (Fig. 5). Lithic pieces matched in this way are likely to have originated from the same nodule and consequently, the same reduction episode (after Villa, 1990; Sellet, 1995). To conduct the analysis, lithics from both the LKKU and MKKU were laid out and mixed together in order to reduce bias that would favour matches within the 2 units. The vertical distances between matched

lithics, based on refitting and nodule analysis are plotted in Fig. 6. Below, the results of the refitting and nodule analysis for the LKKU (Section 4.3) and MKKU (Section 4.4) are first presented separately, while the implications of the data for that site as a whole are presented in the site integrity section (5.3) of the discussion. 4.2. Clarens Formation The bedrock at Kudu Koppie consists of Clarens Formation sandstone, which is composed of moderate to well-sorted, fine to very fine-grained quartz (Bordy and Catuneanu, 2002). In the main excavation the superior erosion interface is characterized by irregularities, small depressions and a pronounced gully that is NW–SE orientated, from 221 cm (uppermost point in square 4S/3E) to 241 cm in the lowest (square 1N/2E).

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Fig. 3. Stratigraphic profile of west wall of Kudu Koppie main excavation with a photo shoving (different scale) part of the profile.

4.3. Lower Kudu Koppie Unit Directly overlying the bedrock is the Lower Kudu Koppie Unit (LKKU) (Fig. 3), which is composed of two levels, the LKKU-1 and LKKU-2. LKKU-1 was found immediately overlying the bedrock, and is a 2 cm thick lens of sterile fine sand. This level is only represented in a single unit of the excavation (2S/4E). LKKU-2 is composed of a clast-supported, pebble to cobble gravel (Udden–Wentworth

scale), dominated by sub-angular to sub-rounded sandstone fragments (average size 2–5 cm), with no fabric (random orientation) and a matrix consisting of gravelly sand; the unit lies on the bedrock throughout most of the excavation, but it is stratified above (LKKU-1) in 2S/4E. It is not present in all squares, but where it is present, the unit demonstrates variable thickness across the site, from 20 cm (west wall of 2S/2E) to 90 cm (north wall 2S/4E). LKKU-2 contains ESA tools, including handaxes, cleavers and picks (Pollarolo, 2004; Pollarolo and Kuman, 2009), bone fragments,

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Fig. 4. Stratigraphic profile of north wall of Kudu Koppie main excavation with a photo shoving (different scale) part of the profile.

seeds (that have yet to be analysed) and fragmentary teeth, mainly of bovids. This unit is also present in Test Pit #3, represented by a horizon with a variable thickness from 15 cm (east–west wall) up to 50 cm (northwest wall). A total of 43 sets of the matched lithics using the methods described in Section 4.1 were from the LKKU (Fig. 6). One of these sets consisted of a pair of refitting lithics, both recovered from 176 cm below datum. The analysis also demonstrated that some artefacts had been displaced vertically within the sedimentary matrix. The maximum vertical displacement between matched lithics in LKKU

was 55 cm (Fig. 6), and the average displacement was 13.37 cm (sd ¼ 16.89, n ¼ 43). The small amount of vertical displacement could reflect either movement within the deposit due to deflation or bioturbation (i.e. termites, cf. McBrearty, 1990), the irregular and sloping surface of the talus, or a combination of various factors. 4.4. Middle Kudu Koppie Unit The Middle Kudu Koppie Unit (MKKU) (Fig. 3) represents a deposit of sandstone rubble weathered directly from the koppie.

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Fig. 5. Refitting quartzite flakes from the MKKU of Kudu Koppie (a). Lithics originating from the same nodule based on colour, texture, and grain size at 10 magnification (b).

The MKKU is a clast-supported, cobble to boulder-sized gravel (Udden–Wentworth scale), dominated by angular to sub-angular sandstone (up to 40 cm.) with no fabric evident (random orientation), and with a matrix consisting of poorly sorted gravelly sand. It has a variable thickness from 34 cm (west wall 4S/3E) to 1.48 cm (west wall 1N/2E). In one square (1S/3W), MKKU seems to be the only unit present. Here, it exhibits a minimum thickness of 38 cm on the east wall and up to 60 cm on the north wall. The lowest point of the MKKU occurs at 235 cm below datum in the corner of north wall, corresponding to a dipping of the unit towards the west. In square 1S/3W, the distinction between the MKKU and LKKU-2 units is not obvious, but LKKU-2 type artefacts are concentrated at the bottom of the unit. The shift from the smaller sandstone subangular to sub-rounded pebbles of the LKKU to the larger sandstone angular and sub-angular cobbles of the MKKU is a gradual one. There is no distinct separation or depositional gap between the 2 units. Some ESA material extends into the base of MKKU, but for the most part the unit is associated with typical MSA artefacts, which includes some bifacial retouched points, Levallois cores and numerous flakes. Bones (under study) consist mainly of bovid dental fragments and seeds (unstudied) are also present. 37 sets of lithics matched using the refitting and nodule analysis described above were recovered from MKKU (Fig. 6), with seven sets consisting of refitting lithics. Three of these sets of refitting lithics indicate no vertical movement within the sedimentary matrix, two sets are separated by 5 cm (one excavation level) and two sets are separated by 10 cm (two excavation levels). The maximum displacement between matched lithics in the MSA levels is 30 cm, and the average displacement is 8.38 cm (sd ¼ 6.78, n ¼ 37). Interestingly, the refitting and nodule analysis indicates that the degree of vertical displacement in the MKKU is less than the LKKU. Both the maximum displacement and the average displacement

between matched lithics are greater in the LKKU. An unequal variance t-test confirms that the difference between the average artefact displacement for the MKKU and LKKU is statistically significant (t ¼ 6.5747, p ¼ 6.6468E09). The unequal variance t-test is used as an alternative to the basic t-test when variances are very different. This observation implies that the LKKU assemblage was more affected by vertical displacement processes than the MKKU, perhaps due to time-related factors. 4.5. Upper Kudu Koppie Unit Overlying MKKU is the Upper Kudu Koppie Unit (UKKU), a late Pleistocene to Holocene sand mantle that covers most of the region. The UKKU consists of sand characterized by a loose surface (disturbed) of poorly sorted, slightly gravelly sand (2–3 cm thick) that overlies a poorly sorted, more consolidated slightly gravelly sand, with a gravel component (up to 2–4 cm) present. Individual quartz grains and clasts of sandstone are visible. The grain size of the sand mantle increases slightly with depth. Modern roots are present, especially in the top 30 cm. Occasional bits of charcoal have also been recovered from the UKKU, along with what appears to be a portion of younger burnt tree root. This suggests that the charcoal is probably also younger than the deposit and not worth dating. At the base of the UKKU there is an 8–9 cm thick layer of poorly sorted gravelly sand, with sandstone clast pebbles up to 8–9 cm in length. This layer was only visible in the southern wall cross-section of square 3S/3E. The UKKU is of variable thickness, from 56 cm (south wall 2S/4E) to 162 cm (north wall 1S/3W) in the main excavation, and up to 250 cm in Test Pit #3. It is clear that the thickness of the UKKU gradually increases as the distance from the koppie increases. Because of the large clast-supported nature of the underlying MKKU, there appears to be some filtering down of upper sediments within the contact zone between the 2 units. The

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Fig. 6. Vertical displacement of artefacts based on refitting and nodule analysis. Vertical lines represent the distance between the maximum and minimum levels from which the artefacts of contemporaneous artefacts were recovered. Refitting artefacts are identified with light grey diamonds. There is no exchange of archaeological material between the two deposits, which are divided by a 15 cm wide contact zone.

top of the sand mantle near the koppie is brown in colour due to an accumulation of organic remains, indicating that vegetation flourished close to the koppie. Farther from the koppie towards Test Pit #3, the colour of the sand gradually changes from brown to orange, consistent with a decrease in vegetative growth far from the koppie. Microfaunal remains and seeds (some burnt) were also recovered from the UKKU. The sand in this area consists of grains derived from the aeolian sand weathered mainly from the Clarens Formation rock, and it is free of alluvial sediment (Kuman et al., 2005a; Le Baron, 2007). A granulometric analysis of a sample taken from the UKKU confirmed the results of Le Baron (2007) analysis, which had sampled the sand mantle at Test Pit #3. Seven OSL samples from the three sites – Hackthorne, Keratic Koppie, and Kudu Koppie – were collected in August 2004 and analysed by Jacobs and Collett (2005). Of the five samples that yielded results, two of them (KUDU 2 and KRK 1) yielded late Holocene ages, but their high overdispersion values indicate the dates are unreliable (Table 1). The samples yielding the lowest overdispersion values, however, suggest that the bulk of the sand cover accumulated in the late Pleistocene ca 15–23 000 years ago. 5. Discussion 5.1. Site formation Farrand (2001) defined the sediments that accumulate in a shelter or cave as three broad types: geogenic, biogenic and Table 1 Summary of OSL results for the sand mantle at Kudu Koppie (KUDU 1 and KUDU 2), Keratic Koppie (KRK 1 and KRK 3), and Hackthorne (HT 3). Samples

Age (ka)

Depth (cm) from surface

Overdispersion (%)

KUDU 1 KUDU 2 KRK 1 KRK 3 HT 3

15.0 2.7 2.2 23.3 15.8

111 41 26 180 80

12 25 37 11 18

    

0.8 0.7 0.9 1.1 1.1

anthropogenic, with any combination and percentages between them. Whilst the geogenic sediments may originate either in or outside the place for several reason (e.g., roof fall by spalling, collapse or through aeolian transport), the biogenic sediments derive from animals and plants that for many reasons have accumulated within or near to the site. The anthropogenic contribution, which can be a considerable percentage of the total sediment accumulation, derives from intentional or unintentional human acts. For Kudu Koppie, it was important to define and understand the 3 units (LKKU, MKKU and UKKU) in terms of their lithology, the preservation of bones and botanical remains, refitting of artefacts, and chronology. Kudu Koppie represents a unique situation in the region, particularly when compared with the other two single-level sites in the area, Hackthorne and Keratic Koppie. Excavation at Kudu Koppie has provided important information about the ESA and MSA occupations in northern South Africa (Pollarolo and Kuman, 2009). The excavations and tests pits have helped us to understand some of the site formation processes that affected Kudu Koppie and demonstrate the overall integrity of the site stratigraphy. Based on this analysis, the lithologies of the LKKU and MKKU units represent distinct depositional events created by the disintegration of the adjacent koppie. The buried sediments at Kudu Koppie site correspond to a characteristic talus slope pattern of deposition, where the deposits decrease in thickness as the distance from the koppie increases. The bone remains and the high number of refitting pieces (for the sample studied), are also consistent with a sheltered site, in contrast to the open-air sites in the region, Hackthorne and Keratic Koppie. Although Keratic Koppie does preserve conjoining sets of artefacts, the material occurs in an unstratified, conflated horizon. At Kudu Koppie, people probably occupied the space beneath the large overhang visible at the site today, possibly bigger in the past, and their debris accumulated in the talus deposit adjacent to the koppie (Fig. 2). The range of sediments that characterize the inclined talus deposits within the excavation is today visible on and around the koppie as products of the natural degradation of the koppie itself. The morphology of the MKKU sandstone clasts is consistent with exfoliated debris from the vertical walls of the

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koppie today, as it was in the past for the roof of the shelter. Small sub-angular and sub-rounded sandstone nodules (average size 2–5 cm) consistent with the LKKU deposit are, today, exposed along the surface of the koppie and could represent a later stage of degradation. Certainly the deposition of the LKKU and MKKU took place during the Pleistocene, based on the presence of ESA and MSA lithics throughout the sequence. It is still unclear whether the formation of the rockshelter took place during the Middle Pleistocene occupation or before. The matrix of the LKKU, which is associated with the ESA, could suggest some transport by water. It is difficult to determine the degree to which water transport may have played a role in the formation of the LKKU sediments. The pronounced NW–SE orientated gully on the face of the bedrock exposed in the excavation (which cut through the LKKU in the square 1S/2E, and a small part of the square 2S/2E, leaving only the MKKU as visible sediment in the stratigraphic section) may suggest this was the case. However, the refitting lithics in LKKU, along with the random orientation of the matrix and the lack of fabric, suggest water transport of sediment was less significant than colluvial accumulation. Weathering of the koppie was likely influenced by climatic conditions, resulting in a continuous and slow, or intermittent, exfoliation of the koppie surface. The glacial/interglacial cycles known for higher latitudes also created climatic oscillations of cooler/drier and warmer/wetter climates related to atmospheric and ocean circulation patterns for the sub-tropics (Gasse, 2000; Tyson and Partridge, 2000; Gasse et al., 2008). While we cannot yet provide a relative age for the MSA levels at Kudu Koppie, the late ESA levels are probably 300 000 year old or older (Kuman et al., 1999). 5.2. Site function Since prehistoric human occupations are usually related to the availability of vital resources such as water, animal and/or vegetable foods (Sikes, 1994), what Kudu Koppie may have offered the late ESA and MSA hominids that used the site can be questioned. The koppie no doubt offered shade and shelter for protection from the elements, as well as a platform for observing the surrounding landscape. It is also plausible that the koppie could have served as a sort of home base. Located a short walking distance to the Limpopo River, it had access to both riverine and woodland resources to the north, and possibly some access to more open habitat resources to the south. Kudu Koppie may represent a palimpsest of various activities that occurred adjacent to the koppie over the course of the late ESA and MSA occupations of the Limpopo Region. If this were the case, the koppie is likely to have as served as a ‘‘central place’’, providing shade and shelter, located near the Limpopo River where floral and faunal resources would have been most accessible. Hominids may have continuously reused the site. These reoccupations may have served different functions and the hominids may have conducted various activities with each occupation. The discrete nature of the two cultural units also suggests abandonment of the region during an intervening period when climates may not have been favourable. No fauna has been recovered from the other two excavated sites of the area (Kuman et al., 2005a,b), but both units (LKKU and MKKU) at Kudu Koppie have yielded bone and dental fragments. Although the faunal analysis is still in process, fauna were recovered from all squares in the excavation and throughout the majority of levels. The vast majority is highly fragmented bone and tooth enamel. Although much bone may have been broken by falling koppie rock, it is likely that the original assemblages were already highly comminuted, which is typical of human processing. Some larger pieces clearly were broken when fresh and some have been refitted.

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Furthermore, lithic resources are abundant in the entire region, eroding both from the escarpment surface and in gullies along its face. Lithic analyses reveal that 31.65% of the 20 867 artefacts recovered from a single square unit (3S2E) are less than 10 mm in maximum length and 44.01% are between 10 mm and 20 mm (Kempson, 2007). The abundance of artefacts of diminutive size, together with the presence of all stages of lithic manufacture (Kempson, 2007), implies that lithic reduction occurred on site. The site may have served as a comfortable venue for tool manufacture in the shade and shelter of the koppie and its trees. A taphonomic study of the fauna is nearly completed, and details of the lithic assemblages are in preparation. However, it is safe to say that Kudu Koppie served as long-term venue for both human tool making and feeding activities. 5.3. Site integrity Unlike the sites of Hackthorne and Keratic Koppie, Kudu Koppie has yielded abundant ESA and MSA lithics in two distinct units and maintained its stratigraphic integrity. In total, 192 pieces were confidently matched using the refitting and nodule analysis described above, 85 nodules identified, and 8 sets of lithics refit. The vertical distances between matched and refit pieces are plotted in Fig. 6. There is not a single nodule whose individual components demonstrate a vertical displacement that crosses the contact zone of the two deposits (Fig. 6). Any artefact recovered from 136 cm and below can be confidently attributed to a distinct archaeological entity, while artefacts recovered from above 121 cm belong to a later industry. In other words, a lithic recovered from 140 cm below datum, for example, is not likely, based on this analysis, to refit or be matched with any lithic from above 121 cm. Conversely, a lithic recovered from above 110 cm is not likely to refit or be matched with any lithic from below 136 cm. There is not a single nodule whose individual components demonstrate a vertical displacement that completely crosses the contact zone of the two deposits (Fig. 6). A small amount of mixing may have occurred only where the two stratigraphic units contact each other, but not beyond a 15 cm wide boundary. This degree of overlap is not unexpected given the cobble to boulder-size matrix of very irregular texture. The refitting and nodule analysis is also consistent with the independent observation regarding sedimentology presented above that the upper limit of the LKKU occurs at about 135 cm below surface in the southwest corner of the excavation (Fig. 3). The refitting and nodule analysis discussed here is based on a limited sample (incomplete samples from only three squares). However, the good recovery of refitting pieces and matched nodule components in this sample suggests that a more thorough and systematic refitting program would result in many more conjoining and matching elements, Kudu Koppie’s potential for refitting therefore could contribute to more detailed study of the ESA and MSA technologies. Several nodules observed here were composed of both cores and flakes, sometimes exhibiting up to 3 flakes per core. Other nodules were represented solely by flakes, with up to 10 flakes resulting from the same nodule. The refitting analysis may also indicate that: (1) the site is in primary or near-primary context; and (2) core reduction occurred on site. This interpretation is further supported by the abundance of artefacts of diminutive size, as discussed above. In the southwest corner of the excavation (3S/2E, 3S/3E, and 2S/2E), all the MSA lithics are contained within the coarser sediment matrix and all the ESA lithics are associated with the smaller sediment matrix. However, the northwest area of the excavation, which has not yet been analysed, lacks the smaller sediment matrix characteristic of the LKKU (Fig. 2). In these squares, there may not

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be a stratigraphic correlation between artefact industry and the type of matrix, yet there may be cultural units that are independent of sediment type. Large core tools that may be characteristic of the ESA seem to be restricted to 121 cm or more below datum. It has also been observed that material belonging to the MSA levels is much fresher in appearance than artefacts in the underlying ESA levels (Kempson, 2007). The stratigraphic integrity of the eastern area of the excavation seems to have been very well preserved because it lies closer to the koppie, which provided a more sheltered position with regard to weathering and soil turbation. 5.4. The UKKU In this study, analysis of the UKKU unit was limited to identification of site formation processes. Two small LSA assemblages have been recovered from these levels. Pottery fragments are localised in the upper part of the sand mantle and microlithic segments in the lower part. Based on this evidence and dates from the sand cover, it appears that two phases of LSA are contained in the sand cover, a Holocene LSA and a Pleistocene accumulation. The contact period for LSA hunter–gatherers and Iron Age people is less than 2000 years ago in this region of South Africa, which suggests a maximum age for the upper LSA, but hunter–gatherers continued to live in the area for centuries after the appearance of Iron Age habitants. In many places in the area, Le Baron (2007) test pits showed that the younger sand mantle directly overlies terrace deposits of Miocene-age or bedrock of the Clarens Formation many millions of years older. This disconformity implies that a large scale erosional phenomenon affected the region at some time prior to the Late Pleistocene. 5.5. Dating Dating of the two lower units at Kudu Koppie, LKKU and MKKU, would be ideal given the rarity of late ESA and MSA assemblages occurring in stratified context. In South Africa dating is extremely difficult due to the fact that organic remains are only rarely preserved and volcanic materials are absent, although bio-stratigraphically useful faunal remains have been found in some sites (e.g., Kathu Pan and Elandsfontein; Klein, 2000). For Kudu Koppie, tooth and enamel fragments are now being investigated with the laser ablation technique for Uranium–Thorium dating. The application of another dating method, cosmogenic nuclide burial dating, is also being attempted. However, this technique relies upon the deep burial of samples, and it may only prove to be useful for the MSA levels. Radiocarbon dating is only suitable for the UKKU. The results of the OSL analysis of the sand mantle at Kudu Koppie, as well as the nearby sites of Keratic Koppie and Hackthorne, are presented in Table 1. It is clear that for two of the samples (Krk1 and Kudu) overdispersion rates indicate unreliable ages. For the KUDU 2 sample, taken from the main Kudu Koppie site excavation, the age of 2.7  0.7 ka is probably underestimated due to beta-ray heterogeneity (Nathan et al., 2003; Thomsen et al., 2005; Jacobs et al., 2008). Values of palaeodose overdispersion of over 20% are likely to represent, according to Olley et al. (2004), any of the following causes: 1. Beta dose heterogeneity; 2. Partial bleaching; or 3. Post-depositional disturbance, resulting in the intrusion of grains from underlying or overlying sediments. The decrease in age with increasing sample depth could perhaps imply a progressive deposition for the sand mantle. 6. Conclusions The evidence presented in this paper emphasises the stratigraphic integrity demonstrated by the site of Kudu Koppie, in

contrast to other excavated sites in this study area of the Limpopo region, and it presents a new interpretation for the site formation processes of the site. An overhanging structure to the outcrop on its southwestern side significantly contributed to sediment accumulation and to protection of deposits from the elements. Today, the koppie has a remnant of that structure. Such a physical setting has not been found at any other koppie site yet investigated in the park, including Keratic Koppie (Pollarolo, 2004; Kuman et al., 2005a,b; Kempson, 2007; Le Baron, 2007). For this reason, the archaeological material at Kudu Koppie has the potential to inform us of the ESA/ MSA technological and behavioural shifts in this part of South Africa, especially given the rarity of stratified contexts attributed to this time period throughout Africa. Additionally, analysis of the site formation processes at Kudu Koppie may contribute to our understanding of climate change in the northern part of South Africa and the effect of Pleistocene climate patterns on human occupation during the late ESA and MSA. Acknowledgments We thank the participants of the International Field Schools from 2004 to 2007, as well as Wits students and other excavators. The Paleontological Scientific Trust (P.A.S.T.) provided K.K. and L.P. finance for the excavation and postdoctoral funding in 2008. Wits University provided L.P. a Postdoctoral Research Fellowship for in 2006–2007. The National Research Foundation, Wits University Research Office, and De Beers Educational Trust provided funds to K.K. for excavations and laboratory work. Funding for part of this research was also provided to J.W. by the Social Sciences and Humanities Research Council of Canada. Thanks to Warwick Mostert, the Manager of the Venetia Limpopo Nature Reserve, and his staff for logistical support. Thanks to the director of the Mapungubwe National Park, in particular to Pabalo Mohafa, and to the owners of the Samaria 1 farm, the Moerdyk family, with particular thanks to Michael Moerdyk (deceased), who brought the Samaria sites to our the attention. Many thanks to Henry Cameron for his friendship as well as Franz Venter, Geeske Langejans, Morris Sutton and Franco Cataldo, who came from Italy with the intention to help. Special thanks are due to Vittorio Garilli for precious comments on previous drafts, and to Piero Ricordi for providing me the sediment analysis. Thank you also to Steve Tooth for his previous stratigraphic interpretations and to Mandy Bryant for highlights comments and ideas. L.P. also expresses his warmest thanks to Sam Phaladi who recently passed away. References Aldis, D.T., Benson, J.M., Rundle, C.C., 1984. Early Jurassic pillow lavas and palynomorphs in the Karoo of eastern Botswana. Nature 310, 302–304. Armstrong, A.L., 1931. Rhodesian archaeological expedition (1929): excavations in Bambata Cave and researches on prehistoric sites in Southern Rhodesia. Journal of the Royal Anthropological Institute 61, 239–276. Barham, L., 2001. Central Africa and emergence of regional identity in the Middle Pleistocene. In: Barham, L., Robson-Brown, K. (Eds.), Human Roots: Africa and Asia in the Middle Pleistocene. Western Academic and Specialist Press, Bristol. Beaumont, P.B., Vogel, J.C., 2006. On a timescale for the past million years of human history in central South Africa. South African Journal of Science 102, 217–228. Bromage, T.G., Schrenk, F., 1999. African Biogeography, Climate Change and Human Evolution. Oxford University Press. Bordy, E.M., 2000. Sedimentology of the Karoo Supergroup in the Tuli Basin, Limpopo River Area, South Africa. Ph.D. thesis. Rhodes University, South Africa. Bordy, E.M., Catuneanu, O., 2001. Sedimentology of the upper Karoo fluvial strata in the Tuli Basin, South Africa. Journal of African Earth Sciences 33, 605–629. Bordy, E.M., Catuneanu, O., 2002. Sedimentology and palaeontology of upper Karoo aeolian strata (Early Jurassic) in the Tuli Basin, South Africa. Journal of African Earth Sciences 35, 301–314. Chazan, M., Ron, H., Matmon, A., Porat, N., Goldberg, P., Yates, R., Avery, M., Sumner, A., Horwitz, L.K., 2008. Radiometric dating of the earlier Stone Age sequence in excavation I at Wonderwerk cave, South Africa: preliminary results. Journal of Human Evolution 55, 1–11.

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