West African Archaeology

West African Archaeology New developments, new perspectives Edited by

Philip Allsworth-Jones

BAR International Series 2164 2010

Published by Archaeopress Publishers of British Archaeological Reports Gordon House 276 Banbury Road Oxford OX2 7ED England [email protected] www.archaeopress.com

BAR S2164

West African Archaeology: New developments, new perspectives

© Archaeopress and the individual authors 2010

ISBN 978 1 4073 0708 4 Cover illustration: Applied figurines on a fragmentary vessel from Janruwa, courtesy of Nicole Rupp

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Ounjougou: a long Middle Stone Age sequence in the Dogon country (Mali) Dr Sylvain Soriano ArScAn - AnTET, université Paris Ouest, CNRS, 21 allée de l'université, 92023 Nanterre, France. [email protected]

Dr Michel Rasse Université de Rouen, Département de Géographie, 76821 Mont Saint-Aignan, France [email protected]

Dr Chantal Tribolo

CRP2A, université Bordeaux 3, CNRS, Esplanade des Antilles, 33607 Pessac, France [email protected]

Pr Eric Huysecom

Université de Genève, département d'anthropologie, CP511, 1211 Genève 24, Suisse [email protected] Abstract West Africa at the moment is totally absent from discussions relating to the Middle Stone Age. Sites belonging to this period have been known in this region for a long time, but their stratigraphic context has frequently been unsure or is completely lacking. As in southern Africa and in western Europe, progress in our knowledge of this stage depends mainly on the construction of a general chronological framework, preferably correlated with worldwide climatic changes and supported by absolute dates. For this reason the study of the complex of open air sites at Ounjougou has opened up a new perspective on the MSA in West Africa. Almost 30 archaeological levels belonging to the period have been identified within thick Pleistocene deposits, most of aeolian origin. Systematic recovery of OSL dates has allowed this sequence of deposits to be determined chronologically, and the many palaeolithic occupations have thus been indirectly dated. The oldest MSA occupations are dated to the end of the Middle Pleistocene, about 150 kyrs ago. They are more numerous between 80 and 25 kyrs ago, with a particular concentration in isotopic stage 3. As usual in open air sites, the density of material within these archaeological levels is very variable, and only the lithic industries have been preserved. Apart from the frequency of occupation, the originality of this archaeological sequence resides in the diversity of these industries, which follow on one from another without any apparent logic. Techniques of manufacture (such as Levallois, discoid, blade, unipolar, or bipolar on anvil) alternate throughout the sequence, and industries characterized by bifacial foliate artefacts occur more than once. If for the most part these industries fit easily enough within the West African MSA as a whole, there are some questions arising with regard to the diversity of technical traditions and their rapid alternation. Are there regional equivalents for this rhythm of change, does it have any particular significance in terms of the peopling of West Africa at this time, and what could have led to these rapid changes? Keywords: West Africa, Middle Stone Age, chronology, settlement

1. Introduction

The study of the Middle Palaeolithic/Middle Stone Age in the African continent has for a long time lacked and still lacks a reliable chronostratigraphic framework. Even for certain emblematic phenomena of this period, such as the Aterian of North Africa, it has only been in the last ten years or so that dates have been published which one could regard as reasonably reliable (Barton et al. 2009; Cremaschi et al. 1998; Garcea 2001; Martini et al. 1998; Mercier et al. 2007; Roset and Harbi-Riahi 2007; Wrinn and Rink 2003). Until a short while ago the absolute chronology of the Aterian rested almost entirely on radiocarbon dates. The same applies to South Africa, where radiocarbon dates alone considerably underestimated the age of the Howieson’s Poort industry, a facies of the MSA which is characterised by the use of blades (Jacobs et al. 2008; Tribolo et al. 2005). One should note that the discovery

of objects having a symbolic significance (engravings and shell beads) has impacted on the debate concerning the emergence of behavioural modernity, and this has given a significant impetus to new dating work (e.g., Bouzouggar et al. 2007). Research concerning this period is very unevenly distributed across the African continent as a whole, and West Africa has been left out of account in the various debates which have taken place over the last few decades. The total absence of any reference to this region in current discussions concerning the origins of modern man in an anthropological and cultural context, and more generally in syntheses concerning the Middle Palaeolithic/MSA, is a case in point (McBrearty and Brookes 2000). After some renewal of activity in the 1980’s (Allsworth-Jones 1

West African Archaeology: New developments, New perspectives

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Figure 1: Location and geomorphological presentation of the site of Ounjougou. 1: Sandstones and scarps in sandstones ; 2 : Main terrace-glacis ; 3 : Eroded sectors of main glacis ; 4 : Holocene terrace (8th millennium BC) ; 5 : Secondary terrace-glacis ; 6 : Sands and silts of alluvial accumulation ; 7 : Hydrographic network and permanent lakes ; 8 : Stratigraphical limits ; 9 : Terraces and glacis edges ; 10 Track and relics of the colonial track; 11 : Height (metres) ; 12 : Archaeological sites ; 13 : Infiltration of Boumbangou through sandstones ; 14 : Palaeoriver of Yamé. affecting this period are now increasingly geared towards diachronic factors.

1980; Allsworth-Jones 1985; Allsworth-Jones 1986; Allsworth-Jones 1987; Chenorkian and Paradis 1982; Descamps 1981; Digara 1988; Marliac 1987; Marliac 1991; Raimbault 1991; Tillet 1997), subsequently very little Palaeolithic fieldwork has been done in West Africa (Hawkins et al. 1996; Ide 2000; Yodé Guédé 1995). The absence of fauna and of fossil hominids in the Pleistocene deposits in this part of Africa probably goes some way to explain this. One has to add the frequently unfavourable preservation conditions which affect Pleistocene sites in the region, and the absence of extended stratigraphies, which is particularly important since research problems

2. Context of the discoveries and Research objectives In this context, the discovery of Palaeolithic archaeological levels stratified in fine-grained sedimentary deposits, in places more than 10 metres thick, in the Dogon country of Mali on the Bandiagara plateau, offered a good opportunity to construct a reference sequence valid for the Palaeolithic of sub-Saharan West Africa as a whole (Huysecom et al. 1999). This Ordovician sandstone plateau includes deep

2

Ounjougou: a long Middle Stone Age sequence in the Dogon country (Mali) irregular hollows which in effect acted as localized traps for thick Pleistocene deposits, aeolian, colluvial, and alluvial.

largely truncated by erosion, either recently or in times past, and the material remains consisted solely of lithic industries, since - as usual in West Africa - no faunal remains were preserved. This means that it would be an illusion to try to reconstruct the function of these sites, or to speculate about the social and economic behaviour of the Palaeolithic groups who were present at Ounjougou.

The credit for the discovery of the first archaeological remains, Neolithic as it happens, goes to Marcel Burri, a geologist at the University of Geneva, who observed them in 1988. Originally the place of discovery was at a locality 15 km east of Bandiagara, but today the term “Ounjougou” refers to a vast complex of archaeological sites extending over practically 10 km2 (Figure 1).

The objective of the present article is therefore to provide a synthesis of our knowledge concerning the Pleistocene occupation of the Dogon country, as it appears as a result of our research, at Ounjougou on the Bandiagara plateau.

It was a brutal change in the course of the river Yamé in the mid 1930’s which revealed the extent and the archaeological potential of these deposits at Ounjougou. At that time the river abandoned a course which it had followed, with an accumulation of alluvial sediments, since the end of the proto-historic period, here dated to an interval between the seventh and thirteenth centuries AD (Rasse et al., 2006). Instead for 50 years it now dug down into its own previous deposits and by erosive action produced a complex system of ravines, which in turn have given us access to long stratigraphic sequences. The existence of these ravines along the path between Bandiagara and Sanga was indicated already by S. Daveau (1959) but their archaeological potential had not been perceived.

3. Thick Pleistocene deposits The Pleistocene deposits which have accumulated on the plateau have a double origin. The coarsest, sands and gravels, come from the disaggregation of the sandstone substratum. The most fine-grained component (silt) - which is clearly dominant - is of allochthonous aeolian origin, even if most of the material has been reworked many times by colluvial and alluvial processes. The principal characteristics of the formations, and the analysis of the contacts between the sedimentary units, allow for the reconstruction of the stratigraphy, in its broad lines (Figure 2). The nature and the geometry of the deposits are the result of two processes (Rasse et al. 2004). The successive aeolian inputs of silt on the plateau have been repeatedly redistributed by colluviation, resulting in a system of glacis (or piedmont slopes) which interlock very tightly. In the valley bottom the fine fraction has been eliminated, downstream, giving way to channels which have been progressively filled up with coarse material. The intercalation of the different formations is the result of the succession of different phases - accumulation and vertical incision - which in turn are clearly linked to hydrological variations in the river Yamé, which it underwent in the course of the Pleistocene.

After two exploratory missions in 1993-1994 and 1996 conducted by the MAESAO team from the Department of Anthropology and Ecology of the University of Geneva (Mission archéologique et ethnoarchéologique suisse en Afrique de l'Ouest), an international research project entitled “Palaeoenvironment and human population in West Africa” was launched in 1997 by Professor E. Huysecom. Today still this project brings together several teams to study the peopling of the Dogon country from the remote past to the present (Huysecom 2002; Huysecom et al. 2004; Ozainne et al. 2009). About a hundred archaeological sites or locations have been discovered covering the Palaeolithic to the historic period. This has provided the scientific framework within which our own research concerning the Palaeolithic has been conducted from 1999 to 2006 (Robert et al. 1999; Robert et al. 2003).

Stratigraphic analysis led to the creation of seven units, labelled U1 to U7 from the oldest to the most recent, very unevenly represented. The complexity of the geometry of the formations, in particular the difficulty of establishing long-range correlations and the absence of soil marker horizons, due to the intense leaching which the deposits have undergone, has complicated the construction of a chronostratigraphic sequence.

The geological and archaeological conditions at these sites are quite similar to those known from the Middle Palaeolithic in the loess plains of northern France: silty deposits of aeolian origin, reworked or not during rainy seasons, very extensive, and regularly cut through by Palaeolithic archaeological levels, where the density of material remains is nonetheless quite low (Tuffreau 2001). These conditions were clearly well suited to a chronostratigraphic and chronocultural approach. We therefore systematically combined in the field the study of the material remains themselves, their geomorphological context, and the dating by OSL of the actual sedimentary deposits (Rasse et al 2004). We gave preference to the diachronic aspect by seeking to find as many remains as possible in distinct stratigraphic positions, rather than trying to open up large areas of the archaeological levels thus located. In most cases the sites had in any case been

If the cumulative thickness of the deposits including each one of these units exceeds twenty metres, still the sedimentary record cannot be said to be continuous and these units are separated from each other by important hiatuses, reflecting in most cases stratigraphic discordances. Thus, U2 and U3 are separated from each other by an important sedimentary hiatus, marked first by the development of a soil horizon and then by significant erosion. Moreover, our knowledge (both archaeological and sedimentological) of these units is uneven, since the oldest (U1 and U2) outcrop only in the deepest ravines. Nonetheless, the Ounjougou sequence can be said to enjoy a high degree of resolution 3


Figure 2: Synthetic transects showing the relative location of the different units recognised for the Pleistocene. This figure also shows the location in the general stratigraphy of the sections sampled for OSL dating. A: schematic EastWest transect of the Oumounaama sector. B: schematic South-West/North-East transects of the Menié-Ménié and Kokolo-Orosobo sectors. (especially for U3-U6).

with the open air sequences known from the Weichselian in the north of France (Antoine et al. 2003) or the rock shelters and caves of the Périgord (Guibert et al. 2008; Mellars 1989), if one takes into account the fact that our record comes from a mere 10 km2.

4. A sequence with high resolution The systematic employment of OSL dates (more than 50) in close association with geomorphological analysis of the formations has allowed us to demonstrate that the sequence developed over a short period of time - from the end of OIS 5 to the middle of OIS 2 for the most part - but with a particularly abundant sedimentological and archaeological record for OIS 3; the preceding periods being represented in a very fragmentary fashion (Tribolo et al. in preparation). Units U3 to U5, which correspond entirely to OIS 3, are thus characterised by marked sedimentary accumulations separated by minor hiatuses. After 30,000 years ago, with units U6 and U7, sedimentation was more discontinuous and above all less developed.

Our work suggests also that for the part of the sequence attributed to OIS 3 there is a possible correlation between the sedimentary events identified at Ounjougou and palaeoclimatic phenomena detected on a global scale (Lespez et al. 2008). Thus, it seems that the sedimentary breaks observed in the Ounjougou sequence, between U3/ U4 and U4/U5, parallel the abrupt Heinrich events (H5 and H4) which are known to have occurred in OIS 3. Although we did not suspect this at the start, the resolution achieved for the continental deposits at Ounjougou in the course of OIS 3 therefore opens up interesting perspectives in which to discuss the dynamics of regional population movement in the Middle Palaeolithic, in the light of global climatic changes and their local expression.

For the whole of the upper Pleistocene sequence we have observed 25 stratigraphically distinct archaeological occurrences between 100,000 and 22,000 years ago, i.e., a mean of one occurrence every 3000 years (Figure 3). If this analysis is confined to the phase for which we have the most detailed and continuous record, within OIS 3 between 50,000 and 30,000 years ago, the corresponding figure would be one occurrence every 1,300 years. Certainly these occurrences are of unequal value, since there are levels marked by only a few isolated pieces as well as others which are much richer, but nonetheless each of them indicates the presence of human groups in the region. Such a high level of archaeo-stratigraphic resolution for the Middle Palaeolithic is unheard of in West Africa and is also impressive on a world scale. It can even be compared

6. Mineral resources abundant but monotonous Although raw materials suitable for knapping are very abundant on the Bandiagara plateau, they are not at all varied. All come from slabs of Precambrian fluvio-deltaic sandstone, including sandstone-conglomerate structures, which make up the plateau. In places, a material with finer granulometry and more marked diagenesis has given rise to sandstone outcrops which are harder and better cemented, so that they become practically quartzitic. This was one of the materials exploited by the Palaeolithic inhabitants. The others come from the sandstone-conglomerate structures.

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Ounjougou: a long Middle Stone Age sequence in the Dogon country (Mali)

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Figure 3: Ounjougou (Dogon country, Mali): synthetic archaeological record for the Upper Pleistocene. Main archaeological levels only are represented. Levels older than Upper Pleistocene are not illustrated. Technological characteristics of the lithic industries are indicated for each archaeological unit.

Mostly these are quartz pebbles, but there are also pebbles of quartzite (less than 5%) and occasionally pebbles of other materials (flint, jasper, and other cryptocrystalline siliceous rocks). Among the materials which could be worked, therefore, there is a contrast between quartz and sandstone, in terms of spatial distribution, availability, and mechanical properties. Quartz pebbles are abundant and omnipresent, both in fluviatile deposits, and in altered products of the sandstone substratum. Their quality is variable, from very good to mediocre, depending on the texture of the material, which oscillates between fine and coarse grained. Quartzitic sandstone by contrast is found in isolated sites dispersed over the landscape where it appears in the form of thick banks. Consequently it allows for the

making of massive pieces either from chunks or large flakes. The quality of the material is sometimes very good, sufficient for the production of bifacial foliate artefacts. Apart from a few cases in the oldest archaeological levels, quartzitic sandstone was always collected at the primary outcrops. By contrast, with regard to the materials which had their origin in the sandstone-conglomerate structures, it should be observed that a significant proportion of these pebbles were collected at secondary sites, in fluviatile deposits of water courses which were active at the time of Palaeolithic occupation. On the basis of these two types of raw material, the Middle Palaeolithic inhabitants of Ounjougou made 5

West African Archaeology: New developments, New perspectives Raw mat. Quartz and quartzite cobbles

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Figure 4: Diversity of raw material procurement and reduction sequences in some MSA industries from Ounjougou. +++: exclusive ; ++ : dominant ; + : minority ; Ø : absent. very different choices when deciding how to create their stone implements: exclusive use either of quartz/quartzite pebbles or of quartzitic sandstone, a combination of these two types of raw material, and collection at primary or secondary sources. Having regard to their relatively poor quality and diversity, raw materials do not seem to have played a decisive role in the systems of lithic production adopted by the knappers (Figure 4). Some groups actually persisted with technical choices which seem to have had little to do with the nature and quality of the raw material: e.g., Levallois technique on little quartz pebbles at Orosobo 2, or blade technique on sandstone at Oumounaama atelier. The diversity of lithic production systems bears witness to this as well.

suggests that these deposits underwent long periods of leaching in warm humid conditions, which is compatible with the cuirass or hardpan phenomena observed. Some sandstone artefacts from U1 do also show signs of chemical alteration in the form of whitened desilicified patches. We cannot objectively evaluate the lapse of time which separated U1 from U2 but it could be quite considerable since (apart from the rare sectors where U1 deposits are preserved) the bedrock has been totally denuded of its weathering products. A technical study of the polyhedrons (De Weyer 2008) has moreover shown that these objects are very similar to the ones from East Africa (Texier and Roche 1995) and the Maghreb (Sahnouni 1985). For these reasons, an age of at least 500 kyrs can certainly be envisaged for this polyhedron industry at Ounjougou.

6. Traces of the first Pleistocene population

While being easily visible archaeologically, the Acheulean up to now has not been found at Ounjougou. This could also confirm the existence of a profound hiatus between the oldest deposits with the polyhedron industry, and the first with industries attributed to the Middle Palaeolithic. On a regional scale, the Acheulean is however present over a vast area, including the river Niger to the north, without being contiguous. The area covered starts with Senegal in the east (Camara and Duboscq 1990; Descamps 1979), includes the Saharan zone with the south of Mauritania (Vernet 1983) the north of Mali (Diop 1972; Gaussen and Gaussen 1995; Raimbault 1991) and Niger (Tillet 1983; Vernet 1996), to finish in Nigeria (Soper 1965). More recently some bifaces have been discovered in Burkina, in the Markoye sector at least 200 km south of Gao (Millogo, communication to the 11th Pan-African Prehistoric Congress, Bamako 2001). The Acheulean, absent at Ounjougou, was nonetheless identified a long time ago on the surface of a rock shelter near Hombori, to the northeast of our study area (Armand 1937).

The oldest traces of human occupation on the Bandiagara plateau appear at Ounjougou in the form of a lithic industry characterised by polyhedrons, sub-spheroids and spheroids in quartzitic sandstone, associated with worked pebbles (Figure 5). These objects, which recall an early phase of the Palaeolithic in terms of typology and technique (De Weyer 2008), have been observed in situ, sealed in packets of hardened coarse sand adhering to bedrock in the MéniéMénié, in the Ravin sud and at Dandoli Ouest. At the first of these locations, the ferruginous packet (which was not very thick) was covered by sandy-silty gravels of different component sizes, much indurated if not cemented: together these form sedimentary unit U1, the oldest at Ounjougou. No attempt has been made to obtain an OSL date for these coarse deposits. A final Middle Pleistocene date, about 150 kyrs, obtained on deposits attributed to U2 in a sondage of the Ménié-Ménié, can be taken as a terminus ante quem for this industry. A further chronological indication is provided by the chemical state of alteration of the bedrock at the contact with U1 - a typical arenaceous product - which 6


Figure 5: Polyhedron in sandstone recovered in a derived stratigraphic position in U2 deposits from La Confluence site. Other polyhedrons were observed in primary older deposits (U1).

Figure 6: Levallois core with preferential removal. This is the oldest evidence for Middle Palaeolithic settlement at Ounjougou (Ménié-Ménié S1).

consists of some flakes in secondary position in a layer of coarse sand in a sondage at Ménié-Ménié (S2). One must nonetheless note that the formations of this age (the base of U2) are not widely preserved and do not appear except very locally, upstream in the deepest ravines. Our windows of observation are therefore much narrower than for the upper Pleistocene, and our vision of the occupations which took place at this time is correspondingly biased.

7. A plateau traversed by the people of the Middle Palaeolithic Apart from the assemblage with polyhedrons, which signifies an ancient human occupation on the Bandiagara plateau, all the other industries found in a Pleistocene context at Ounjougou belong chronologically to the Middle Palaeolithic. A particularly typical Levallois core with preferential removal (Figure 6) found in isolation at Ménié-Ménié (S1) provides the first evidence for the Middle Palaeolithic at Ounjougou. OSL dating evidence suggests that it belongs to the late Middle Pleistocene (OIS 6?). The occupation of the plateau during this early phase of the Middle Palaeolithic seems to have been very slight, since (apart from the first find mentioned above) the only evidence which we can formally attribute to this period

Middle Palaeolithic occupations become more numerous in the upper Pleistocene with a particular concentration in isotopic stage 3 (Figure 3). But it is also at this time that the rhythm of sedimentary accumulation is at its highest, with a correspondingly increased possibility to single out discrete archaeological events.

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West African Archaeology: New developments, New perspectives 7.1. Open air occupations

operation sequence (chaîne opératoire). The exceptions to this rule show that we are in the presence of sites the function and functioning of which could be different. Thus, at the site of Oumounaama atelier “amas” 1996, refittings have confirmed that the by-products of blade production (preparation flakes, exhausted cores, blade fragments) were abandoned on site, while certain of the end-products were exported to be used faraway (Figure 8). The lower layer (C.2) of Ravin de la Vipère provides another example. The very rare refittings achieved in a mass of more than 350 pieces of quartzitic sandstone almost all relate to broken flakes, and no debitage sequence of more than two flakes could be reconstituted. This suggests that what we have here is not a single set of knapping debris in place, but a mass of disparate waste flakes coming from the working of several cores.

All the occupations known for the Middle Palaeolithic of Ounjougou are open air, and in the majority of cases the lithics have been preserved in primary position or only slightly displaced in silty colluvial sediments. In spite of the disappearance of all traces of fauna, the state of conservation can be very good. Thus, 57.7% of the concentration of lithics excavated at Orosobo 2 (n=1378) consisted of pieces less than 10 mm in size, although no sieving was carried out at the time of excavation. This example shows that the burial of objects in these finegrained deposits could be very gentle and operate in such a way as not to deform them qualitatively. The presence of knapping debris permitting extensive refitting at Ravin de la Vipère 3 (Figure 7) is another illustration of good site preservation. Certain assemblages (Oumounaama Px, Oumounaama Butte) were nonetheless recovered in a secondary position in coarse channel deposits. The lithics, smoothed or rolled, show clear traces of transport.

Finally, one should note that in almost all cases retouched tools are rare or even totally absent at Ounjougou, which is also a repeated characteristic of open air sites in the Middle Palaeolithic of Europe (Tuffreau 2001). This characteristic may be exacerbated by the nature of the raw materials (quartz and sandstone) which do not lend themselves easily to retouch (Mourre 1996).

The sites with artefacts in primary position also vary a great deal in respect of the density of material recovered, from several hundred to less than one piece per square

7.2. A marked diversity of technical traditions The diversity of the Middle Palaeolithic industries is very important in the sequence at Ounjougou (Figure 3), since it developed over a relatively short period of time, and the raw materials utilised (quartz, quartzitic sandstone) acted as a constraint in terms of their quality. Most of the lithic industries find their place without difficulty in the Middle Palaeolithic, and most of the usual debitage patterns are represented: Levallois, discoidal, unidirectional, blade (Figures 8 and 9). Even, the bifacial foliate pieces (Figure 10: 1-5) which are found at various places in the sequence (Figure 3) are a frequent element in the African Middle Palaeolithic/Middle Stone Age (Clark 1988; McBrearty and Brooks 2000). Leaving aside these bifacial points and the raw materials employed, most of the industries at Ounjougou are quite similar to the Middle Palaeolithic of Western Europe (Bordes 1992; Jaubert 1999; Otte 1996). The industry of Kokolo 2, made on pebbles of quartz or quartzite, has certain typological and technological characteristics which bring it closer to an archaic Palaeolithic (Figure 9: 10-13) (Soriano 2003), although it is undoubtedly dated to the upper Pleistocene. Other industries seem to be quite original, like Dandoli 1/3 with a debitage technique exclusively employing bipolar on anvil percussion (Figure 9: 3-5) (Soriano et al. in press). Some massive tools which can be described as heavy scrapers (rabots) (Figure 10:6) are known at Ounjougou (Dandoli 2) in a stratigraphic position similar to that of the pieces showing bipolar on anvil reduction just described, but they have never been found in direct association, except on the surface. It is the recent excavation of a little rock shelter in our second study area (70 km south of Ounjougou, along the northern cliff face of the plateau) which has confirmed that these heavy scrapers and a bipolar on anvil technique

Figure 7: Refitting of flakes extracted from a quartz pebble. The flakes were collected in a small knapping scatter from the upper level (C.1) of Ravin de la Vipère 3 (Photo S. Soriano). metre. These variations agree well with what is commonly observed in open air site complexes of this period in Europe (Tuffreau 2001). As in that case, certain very poor archaeological levels at Ounjougou correspond more to archaeological “background noise” or “background scatter” than to true sites occupying a definite time and space locus (or “patch”) (Conard et al. 1998; Roebroeks et al. 1992). In the majority of sites where the remains are in primary position, the lithic assemblage contains all stages of the

8


Figure 8: Oumounaama atelier site: refitting of a blade (n°90) and many flakes coming from platform rejuvenation on a sandstone blade core. Missing blades were probably exported for a faraway use (Photo S. Soriano).

Figure 9: MSA debitage products from Ounjougou: (1, 2 and 6) Flakes from discoid reduction, sandstone, Ravin de la Vipère lower level (U3); (3-5) products from bipolar on anvil reduction, quartz, Dandoli 1/3 (U5); (7, 8) Levallois cores, quartz, Orosobo 2 (U5); (10, 12) chopper-like cores, (11) chopping-tool like core and (9, 13) centripetal cores, quartz, Kokolo 2 (U2).

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Figure 10: MSA shaping products from Ounjougou: (1, 2) Bifacial foliate points, sandstone, Kokolo 3 (U5); (3) Fragment of bifacial piece, quartz, Ravin des Draperies (U6, same level as Oumounaama Butte); (4, 5) Fragments of bifacial foliate pieces, sandstone, Oumounaama Px (U5); (6) Heavy scraper, sandstone, Kokolo 1 (U5, same level as Dandoli 2). do in fact belong to the same industry (Huysecom et al. in press; Tribolo et al. in press). Bifacial foliate pieces have been found at various stratigraphic levels (Figure 3). In several cases, these pieces have been collected in secondary position in fluviatile gravels (Oumounaama Px, Oumounaama butte) (Figure 10: 3-5) and no particular debitage technique can be associated with them. The Kokolo 3 level is in colluvial sediments, but the lithic assemblage is too small to determine what debitage technique was employed to make the flakes associated with the bifacial points (Figure 3). Only the site of Ravin du Kondo (which is currently under study) should allow us to clarify the nature of the industries with bifacial foliate points at Ounjougou.

level quartz was also employed, but in connection with another type of debitage the nature of which has yet to be determined (Figure 3). 7.3. Ounjougou and the peopling of the West African Sahel in the upper Pleistocene The diversity of the lithic industries encountered in the stratigraphy at Ounjougou and their succession without any evident logic raises questions on the dynamics of the way in which the West African Sahel was peopled during the upper Pleistocene. More than the diversity, it is the rhythm of change which is very high, since, it must be remembered, the majority of the occupations took place in the course of OIS 3, a span of 30 millennia. A rhythm of change in technical traditions comparable to this, higher even, has been recognised in the Near East for the Middle Palaeolithic at the open air site of Umm el Tlel (central Syria) in an arid steppe environment (Boëda et al. 1998; Boëda and Muhesen 1993). The succession observed at Ounjougou first of all allows us to exclude the idea of a gradual local evolution in technical traditions during this period. It suggests rather that human groups with different technical traditions succeeded each other repeatedly in this region.

Perhaps more than the diversity of the lithic industries, it is the absence of technological repetition in their chronological succession which deserves to be emphasised. One almost never finds two successive occupations which contain exactly the same lithic industry. Even at the Ravin de la Vipère, where the two successive archaeological levels (lower and upper) are characterised by a discoidal technique, there are still differences. In fact, the discoidal debitage was here achieved on quartz in the upper level and on quartzitic sandstone in the lower level. In this 10

Ounjougou: a long Middle Stone Age sequence in the Dogon country (Mali) This situation is the direct opposite of that which is observed more to the north, beyond latitude 19° N, between 80 and 30 thousand years ago, when the Aterian is the only techno-cultural entity recognized (Cremaschi et al. 1998; Garcea 2004; Martini et al. 1998; Mercier et al. 2007; Roset and Harbi-Riahi 2007; Tillet 1997; Wrinn and Rink 2003). Even if the Aterian is not as monolithic as it appears, with probably geographical and/or chronological facies, all the industries which belong to it have in common a suite of technical practices (such as tanged pieces, Levallois debitage, etc.). This opposition between the sequence at Ounjougou, where each occupation differs from the preceding one in terms of technical traditions, and the Aterian, where the same technical practices were followed for a long time, suggests that there was a frontier separating these two worlds; a frontier which is moreover emphasized by the very abrupt southern limit of the Aterian’s distribution (Tillet 1995).

Tibchi, and Zenabi (Allsworth-Jones 1980; AllsworthJones 1985; Allsworth-Jones 1986; Allsworth-Jones 1987), in Cameroun in the so-called “Douroumian” formations at Mayo Louti (Marliac 1973; Marliac 1987; Marliac 1991), and at Birimi in Ghana where Levallois debitage is associated with discoid cores and bifacial points (Hawkins et al. 1996). At Ounjougou by contrast the Levallois technique is far from being the most frequent in the Middle Palaeolithic industries here represented. 8. By way of conclusion In many respects, the Ounjougou sequence from now on constitutes a reference point for the Middle Palaeolithic in sub-Saharan West Africa. Its stratigraphic completeness and above all its chronological resolution, at least, have no equivalent. The Ounjougou sequence demonstrates first of all that when the geomorphological conditions permit the conservation of upper Pleistocene deposits (and to a lesser extent those of the late Middle Pleistocene), Palaeolithic occupations are also preserved. Research which we have carried out in 2005-2009 in a second sector, along the southern cliff face of the plateau, where the sedimentary context is different, have confirmed this (Rasse et al. in preparation). The results of our research at Ounjougou also show that the continental sequences in this region can provide evidence of subtle but distinct variations in regional hydrosystems which are a response to abrupt global climatic phenomena (Heinrich events) (Lespez et al. 2008).

The systematic and rapid renewal of the Sahelian population which is in evidence at Ounjougou, at least during OIS 3, is intriguing. What could cause it, whereas more to the north with the Aterian, continuity is the rule? For the moment, this question remains open. 7.4. Beyond Ounjougou West Africa does not lack sites attributed to the Middle Palaeolithic or the Middle Stone Age (Allsworth-Jones 1987; Clark 1967; Davies 1967) but their chronology is nonexistent or insufficient. Before the development of such methods as TL, OSL, ESR and U/Th, radiocarbon dating alone was used, and the validity of dates obtained for occupations which could easily exceed the limits of this method is no more than relative. Among the rare sites with radiocarbon dates, we should mention Mayo Louti (Cameroun). Two dates on charcoal coming from a sand horizon above the archaeological layer provide a terminus ante quem of about 15,000 BP for this industry, described as MSA (Marliac 1973; Marliac and Gavaud 1975). The situation is comparable at Bilma (Niger). The radiocarbon date for material in lacustrine limestone of around 33,000 BP also acts as a terminus ante quem for the Middle Palaeolithic industry with Levallois debitage at this location (Maley et al. 1971). Only the site of Birimi (Ghana) has a stratified industry attributed to the MSA which has recently been dated by OSL to about 40,000 years ago (Casey et al. 1997; Hawkins et al. 1996; Quickert et al. 2003). Certain site complexes, rich as they are, as in the valley of the Mékrou in SW Niger, are very difficult to evaluate in the absence of a chronostratigraphical framework (Ide 2000; Vernet 1994). This chronological weakness is a considerable limitation when seeking to compare the Middle Palaeolithic of Ounjougou with other occurrences already known.

Ounjougou demonstrates moreover that sub-Saharan West Africa, or at least certain regions within it, witnessed during the upper Pleistocene a Palaeolithic occupation as dense as in other parts of the continent. The diversity of technical traditions represented by the lithic industries at Ounjougou and above all the rapid rhythm of change suggest that the Sahel did experience regular population movements at this time, the causes of which remain to be determined. There is a striking contrast with North Africa and the Sahara, where the Aterian is ubiquitous between 80 and 30,000 years ago. Acknowledgements The French Palaeolithic archaeological mission at Ounjougou, under the direction of S.S., has been supported financially since 2003 by the Ministry of Foreign Affairs. It is part of an international research programme entitled “Palaeoenvironment and Human Population in West Africa” coordinated by E.H. and financed by the SLSA (Swiss-Liechtenstein Foundation for Archaeological Research Abroad), the FNRS (Fonds National Suisse de la Recherche Scientifique), and the State of Geneva. This programme also received help in 2004 from the FrancoSwiss PAI (Programme d'action intégré) Germaine de Staël. The OSL dating programme was carried out by C.T. thanks to a Marie Curie European scholarship award (MEIFCT-2003-501195). It also formed part of an EFCHED

We can nonetheless note that in West Africa it is Middle Palaeolithic/MSA industries with Levallois debitage which are the most frequently recorded. They are known for example in Nigeria, in the Nok region, at Mai Lumba, 11

West African Archaeology: New developments, New perspectives programme of the Natural Environment Research Council (NERC) (UK). Research on the palaeolithic of Ounjougou further benefitted from financial support under the terms of the CNRS programme ATIP (Action thématique et incitative sur programme) granted to S.S. in 2006/2007.

Syrie) : étude préliminaire des industries lithiques du Paléolithique moyen et supérieur 1991-1992. Cahiers de l'Euphrate 7, 47-91. Bordes, F. 1992. Leçons sur le Paléolithique, tome II. Ed. Presses du CNRS. Bouzouggar, A., Barton, N., Vanhaeren, M., D’errico, F., Collcutt, S., Higham, T., Edward, H., Parfitt, S., Rhodes, E., Schwenninger, J.-L., Stringer, C., Turner, E., Ward, S., Moutmir, A. and Stambouli, A. 2007. 82,000-year-old shell beads from North Africa and implications for the origins of modern human behavior. PNAS 104, 9964-9969. Camara, A. and Duboscq, B. 1990. La fouille d'un site acheuléen à Djita (basse vallée de la Falémé, Sénégal). L'Anthropologie 94, 293-304. Casey, J. L., Sawatzky, R., Godfrey-Smith, D. I., Quickert, N., D'Andrea, A. C., Wollstonecroft, M. and Hawkins, A. 1997. Report of investigations at the Birimi Site in Northern Ghana. Nyame Akuma 48, 32-38. Chenorkian, R. and Paradis, G. 1982. Une industrie paléolithique découverte dans la « Terre de Barre » d’une terrasse proche d’Anyama (région d’Abidjan). Nyame Akuma 21, 18-27. Clark, J. D. (ed.) 1967. Atlas of African Prehistory. Chicago, University of Chicago Press. Clark, J. D. 1988. The Middle Stone Age of East Africa and the beginnings of regional identity. Journal of World Prehistory 2, 235-305. Conard, N. J., Prindiville, T. J. and Adler, D. S. 1998. Refitting Bones and Stones as a Means of Reconstructing Middle Paleolithic Subsistence in the Rhineland. In J.-P. Brugal, L. Meignen and M. Patou-Mathis (eds.), Économie préhistorique : les comportements de subsistance au Paléolithique, 273290. Sophia Antipolis, Éd. APDCA. Cremaschi, M., Di Lernia, S. and Garcea, E. A. A. 1998. Some insights on the Aterian in the Libyan Sahara : chronology, environment and archaeology. African Archaeological Review 15, 261-286. Daveau, S. 1959. Recherches morphologiques sur la région de Bandiagara. Dakar, I.F.A.N. Davies, O. 1967. West Africa before the Europeans: archaeology and prehistory. London, Methuen. De Weyer, L. 2008. Étude technologique de l’industrie lithique du Ménié-Ménié, Ounjougou, Mali. Mémoire de Master 1, Université Paris X - Nanterre. Descamps, C. 1979. Contribution à la préhistoire de l'Ouest sénégalais. Dakar, Faculté des lettres de l'Université de Dakar. Descamps, C. 1981. État des connaissances sur le Paléolithique au Sénégal. Bulletin de l’ASEQUA 6263, 67-73. Digara, C. 1988. Le paléolithique au Cameroun septentrional : Prospection et étude technologique d'ensembles lithiques. Thèse de 3ème cycle, Université Paris X Nanterre. Diop, A. 1972. Lagreich: une station acheuléenne de la vallée du Tilemsi (Mali). Université de Bordeaux. Garcea, E. A. A. (ed.) 2001. Uan Tabu in the settlement history of the Libyan Sahara. Firenze, Edizioni

We would like to thank our Malian partners for their collaboration: Kléna Sanogo (ISH), Doulaye Konaté (Univ. Bamako, FLASH), Lassana Cissé (Mission culturelle de Bandiagara), as well as the villagers of Dimbal, Gologou, Kokolo, Dandoli, Songona and Yawa who participated in our fieldwork. We are grateful to Philip Allsworth-Jones for translation of this paper.

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