D Bahain

A Pleurdeau

J Nankela

Lesur

G Mauran

M Lebon

: O Lapauze

F Détroit

J J Bahain

D Pleurdeau

J Lesur

Archaeological ochres of the rock art site of Leopard Cave (Erongo, Namibia): looking for Later

Keywords:

de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Ochre is the common archaeological name of ferrugi-nous rocks and iron oxides with a high tinting strength. Such materials appear in different geological settings, with varying amounts of iron oxides or iron oxyhydroxides [START_REF] Hodgskiss | Identifying grinding, scoring and rubbing use-wear on experimental ochre pieces[END_REF][START_REF] Hodgskiss | Ochre use in the Middle Stone Age[END_REF][START_REF] Rifkin | Assessing the efficacy of red ochre as a prehistoric hide tanning ingredient[END_REF][START_REF] Rifkin | Processing ochre in the Middle Stone Age: Testing the inference of prehistoric behaviours from actualistically derived experimental data[END_REF]. The study of the collection and use of ochre during the Middle Stone Age is well documented in the archaeology of Southern Africa (see Hodgskiss 2020 for a synthesis of this study). Henshilwood and others have noted the symbolic use of ochre in the evolution of modern human behaviors [START_REF] Henshilwood | Emergence of modern human behav-ior: Middle Stone Age engravings from South Africa[END_REF][START_REF] Henshilwood | An abstract drawing from the 73,000 year-old at Blombos Cave, South Africa[END_REF]. Hence, many studies have been conducted to analyze ochre pieces recovered within MSA layers (e.g., [START_REF] Barham | Systematic pigment use in the Middle Pleistocene of south-central Africa[END_REF][START_REF] Bernatchez | Geochemical characterization of archae-ological ochre at Nelson Bay Cave (Western Cape Province), South Africa[END_REF][START_REF] Dayet | Ochre resources from the Middle Stone Age sequence of Diepkloof rock shelter, Western Cape, South Africa[END_REF][START_REF] Salomon | Selection and heating of colouring material in the Mousterian level of Es-Skhul (c. 100,000 years BP, Mount Carmel, Israel)[END_REF][START_REF] Hodgskiss | An investigation into the properties of the ochre from Sibudu, KwaZulu-Natal, South Africa[END_REF][START_REF] Hodgskiss | Ochre use in the Middle Stone Age at Sibudu, South Africa: Grinding, rubbing, scoring and engraving[END_REF][START_REF] Moyo | Blombos cave: Middle Stone Age ochre differentiation through FTIR, ICP OES, ED XRF and XRD[END_REF][START_REF] Rifkin | Characterising pigment on 30,000-year-old portable art from Apollo 11 Cave, Karas Region, southern Namibia[END_REF]. In contrast, the use of ochre in LSA contexts is understudied, especially given the large number of rock art sites where ochre has been discovered (Fig. 1; see Online Resource 1). As synthetized by Le Quellec (2018), Southern African rock art studies have long focused on the Drakensberg paintings. Innovative ap-proaches have led to a renewal of rock painting studies in other regions, and these have highlighted the diversity of rock art traditions in Southern Africa [START_REF] Challis | Creolisation on the nineteenth-century frontiers of southern Africa: A case study of the AmaTola 'Bushmen'in the Maloti-Drakensberg[END_REF][START_REF] Challis | Re-tribe and resist: The ethnogenesis of a creolised raiding band in response to colonisation[END_REF][START_REF] Le Quellec | The rock art of sub-Saharan Africa. The Oxford handbook of the archaeology and anthropology of rock art[END_REF][START_REF] Ouzman | The magical arts of a raider nation: central So ut h Afr ica's Ko r an a r oc k ar t[END_REF]). Significant works have been carried out to characterize the pictorial layers of these paintings (Bonneau et al. 2012[START_REF] Bonneau | Comparing painting pigments and subjects: The case of white paints at the Metolong dam (Lesotho)[END_REF][START_REF] Hughes | A preliminary study of ochres and pigmentaceous materials from KwaZulu-Natal, South Africa: Towards an understanding of San pigment and paint use[END_REF][START_REF] Mauran | First in situ pXRF analyses of rock paintings in Erongo, Namibia: Results, current limits and prospects[END_REF][START_REF] Prinsloo | The first Raman spectroscopic study of San rock art in the Ukhahlamba Drakensberg Park, South Africa[END_REF][START_REF] Tournié | The first in situ Raman spectroscopic study of san rock art in South Africa: Procedures and preliminary results[END_REF][START_REF] Van Rijssen | Analysis of South African rock art pigments by X-ray fluorescence spectroscopy (EDS)[END_REF] and date them directly or indirectly [START_REF] Bonneau | Comparing painting pigments and subjects: The case of white paints at the Metolong dam (Lesotho)[END_REF][START_REF] Bonneau | The earliest directly dated rock paintings from southern Africa: New AMS radiocarbon dates[END_REF][START_REF] Mazel | Dating the Collingha shelter rock paintings[END_REF][START_REF] Mazel | Accelerator radiocarbon dating of Natal Drakensberg paintings: Results and implica-tions[END_REF][START_REF] Watchman | Dating rock paintings in the uKhahlamba-Drakensberg and the Biggarsberg, KwaZulu-Natal, South Africa[END_REF]. Others sought to identify the regional specificities of the different South-ern African rock art clusters [START_REF] Challis | Creolisation on the nineteenth-century frontiers of southern Africa: A case study of the AmaTola 'Bushmen'in the Maloti-Drakensberg[END_REF][START_REF] Challis | Re-tribe and resist: The ethnogenesis of a creolised raiding band in response to colonisation[END_REF][START_REF] Eastwood | Fingerprints of the Khoekhoen: Geometric and handprinted rock art in the Central Limpopo Basin, southern Africa[END_REF][START_REF] Smith | Taking stock: Identifying Khoekhoen herder rock art in Southern Africa[END_REF]). Some studies have analyzed the paintings' scenic narratives and explored the interactions between the rock arts and their environment [START_REF] Breunig | Destroyed rock art: Signs of conflict between prehistoric hunter-gatherers groups on the edge of northwest-ern Namibia's Namib desert[END_REF][START_REF] Breunig | West of the best: Rock art and archaeological discoveries in the Doro! Nawas region of northwest Namibia[END_REF][START_REF] Lenssen-Erz | The landscape setting of rock-painting sites in the Brandberg, Namibia: Infrastructure, Gestaltung, use and meaning[END_REF][START_REF] Holl | Beyond shamanism: Dissecting the painting from Snake Rock in Namibia[END_REF][START_REF] Nankela | Rock art research in Namibia: A synopsis[END_REF][START_REF] Nankela | Rock art and landscape: An empirical analysis in the content, context and distribution of the rock art sites in Omandumba East and West, Erongo Region Namibia[END_REF].

The discovery of ochre within LSA archaeological layers below rock paintings has often led researchers to consider that ochre was used only for rock paintings and that the discarded ochre pieces are waste materials. Therefore, these materials remain understudied (e.g., [START_REF] Breunig | Der Brandberg. Untersuchungen zur Besiedlungsgeschichte eines Hochgebirges in Namibia[END_REF][START_REF] Kinahan | Four thousand years at the Spitzkoppe: Changes in settlement and landuse on the edge of the Namib Desert[END_REF][START_REF] Richter | Studien zur Urgeschichte Namibias[END_REF][START_REF] Vogelsang | Middle-Stone-Age-Fundstellen in Südwest-Namibia[END_REF][START_REF] Vogelsang | Under the mopane tree: Holocene settlement in northern Namibia[END_REF][START_REF] Wendt | Preliminary report on an archaeological re-search program in south West Africa[END_REF]). As a result, only four multianalytical studies have been conducted on the ochre finds from Southern African LSA contexts [START_REF] Bernatchez | Geochemical characterization of archae-ological ochre at Nelson Bay Cave (Western Cape Province), South Africa[END_REF][START_REF] Hahndiek | Of pigments and paint: Quantifying ochre and rock art in the Cederberg (Western Cape, South Africa)[END_REF][START_REF] Hughes | A preliminary study of ochres and pigmentaceous materials from KwaZulu-Natal, South Africa: Towards an understanding of San pigment and paint use[END_REF][START_REF] Steele | Varsche Rivier 003: A Middle and Later Stone Age site with Still Bay and Howiesons Poort assemblages in Southern Namaqualand, South Africa[END_REF], despite the large number of sites where LSA ochres have been recovered. During their prelim-inary work on LSA ochres from four rock art sites in KwaZulu-Natal, [START_REF] Hughes | A preliminary study of ochres and pigmentaceous materials from KwaZulu-Natal, South Africa: Towards an understanding of San pigment and paint use[END_REF] pointed to the lack of knowledge about ochre resources. Their preliminary work demonstrated that the ochres from these sites were of high diversity and might be correlat-ed to the rock art in the area. But they could not go further with their study due to the diversity of sites they studied, both chronologically (1,290-9,180 years BP) and geographically.

To our knowledge, only a doctoral thesis correlates ochre from LSA layers and rock paintings at Andriesgrond, Diepkloof, and De Hangen [START_REF] Hahndiek | Of pigments and paint: Quantifying ochre and rock art in the Cederberg (Western Cape, South Africa)[END_REF]. This study noted that it is difficult to ascertain the relationship between the rock paintings and the ochre fragments found below them. Two noteworthy studies have been carried out by [START_REF] Bernatchez | Geochemical characterization of archae-ological ochre at Nelson Bay Cave (Western Cape Province), South Africa[END_REF] at Nelson Bay Cave (Western Cape, South Africa) and [START_REF] Steele | Varsche Rivier 003: A Middle and Later Stone Age site with Still Bay and Howiesons Poort assemblages in Southern Namaqualand, South Africa[END_REF] at Varshe River 003 (Western Cape, South Africa). Both are unpainted LSA-MSA sites that have delivered some ochre fragments. In her study, [START_REF] Bernatchez | Geochemical characterization of archae-ological ochre at Nelson Bay Cave (Western Cape Province), South Africa[END_REF] identified different groups of archae-ological ochres, pointing to the exploitation of different sources at the same time. Thanks to her diachronic approach, she also demonstrated some procurement changes during the Later Stone Age Wilton, Albany, and Robberg occupations of Nelson Bay Cave. In her conclusion, she called for the continuation of this study through provenience studies of Nelson Bay Cave ochres and of other sites in the region. This task was recently completed by [START_REF] Steele | Varsche Rivier 003: A Middle and Later Stone Age site with Still Bay and Howiesons Poort assemblages in Southern Namaqualand, South Africa[END_REF], who excavated Varshe River 003 and conducted geological surveys in the region. The authors noticed diversity in the lithology of the ochre fragments at the site. They considered that this diversity was pointing to the exploitation of numer-ous sources. For them, it could reflect either high mo-bility of the population or a high level of exchange activity. But the connection with other sites and the nature of their use are uncertain. Moreover, ochre provenience studies have not been carried out. Archaeologists have extensively surveyed many sites in Central Namibia for several decades and recorded thousands of rock art sites in different massifs, including the Brandberg, the Erongo, and the Spitzkoppe [START_REF] Breuil | The white lady of the Brandberg[END_REF][START_REF] Breuil | Anibib & Omandumba, and other Erongo sites[END_REF][START_REF] Breunig | West of the best: Rock art and archaeological discoveries in the Doro! Nawas region of northwest Namibia[END_REF][START_REF] Börner | Die Uberprufune der Schamanismus-Theorie anhand ausgewahlter Felsmalerien ausdem Erongo Gebirge, Namibia[END_REF][START_REF] Holl | Beyond shamanism: Dissecting the painting from Snake Rock in Namibia[END_REF][START_REF] Hollmann | A report on the rock paintings in the Erongo Mountain, Erongo Region: Karibib, Omaruru District, Namibia[END_REF][START_REF] Kinahan | Four thousand years at the Spitzkoppe: Changes in settlement and landuse on the edge of the Namib Desert[END_REF][START_REF] Kinahan | Dâures, the burning mountain-issues of research and conservation in the Brandberg of Namibia[END_REF][START_REF] Kinahan | The rock art of /Ui-//aes (Twyfelfontein) Namibia's first World Heritage Site[END_REF][START_REF] Nankela | Rock art and landscape: An empirical analysis in the content, context and distribution of the rock art sites in Omandumba East and West, Erongo Region Namibia[END_REF][START_REF] Pager | The rock paintings of the Upper Brandberg Part 1: Amis Gorge[END_REF][START_REF] Pager | The rock paintings of the Upper Brandberg[END_REF][START_REF] Pager | The rock paintings of the Upper Brandberg: Part 3: Southern Gorges[END_REF][START_REF] Pager | The rock paintings of the Upper Brandberg. Part Umuab and Karoab Gorges[END_REF][START_REF] Pager | The rock paintings of the Upper Brandberg. Part Naib Gorge (A) and the Northwest[END_REF][START_REF] Pager | The rock paintings of the Upper Brandberg. Part Naib Gorge (B) and the Northwest[END_REF][START_REF] Pager | The rock paintings of the upper Brandberg: Part 6, Naib (B), Circus and Dom Gorges[END_REF][START_REF] Scherz | Felsbilder in Südwest-Afrika[END_REF][START_REF] Vallverdu | Nouvelles peintures du massif de l'Erongo S.W.A (Namibie), Drotskie Rock, Anibib I[END_REF]. Excavations have also been carried out to provide archaeological contexts for the various rock art sites and to identify the different phases of human occupation in the region [START_REF] Breunig | Der Brandberg. Untersuchungen zur Besiedlungsgeschichte eines Hochgebirges in Namibia[END_REF][START_REF] Breunig | Destroyed rock art: Signs of conflict between prehistoric hunter-gatherers groups on the edge of northwest-ern Namibia's Namib desert[END_REF][START_REF] Breunig | West of the best: Rock art and archaeological discoveries in the Doro! Nawas region of northwest Namibia[END_REF][START_REF] Kinahan | Four thousand years at the Spitzkoppe: Changes in settlement and landuse on the edge of the Namib Desert[END_REF][START_REF] Pleurdeau | Of sheep and men: Earliest direct evidence of caprine domestication in Southern Africa at Leopard Cave (Erongo, Namibia)[END_REF][START_REF] Richter | Studien zur Urgeschichte Namibias[END_REF][START_REF] Wendt | Preliminary report on an archaeological re-search program in south West Africa[END_REF]. These studies provide valuable insights for understanding central Namibian rock art. However, no investigation was carried out on the ochre assem-blages discovered at the different rock art sites in the region (Table 1, Fig. 1, and Online Resource 1). Nevertheless, some of these studies have discussed the sociocultural contexts of the rock art sites, thanks to the discovery of exfoliated painted flakes within archaeological layers dated to 3,000 BP at Amis 10 [START_REF] Breunig | Der Brandberg. Untersuchungen zur Besiedlungsgeschichte eines Hochgebirges in Namibia[END_REF][START_REF] Pager | The rock paintings of the Upper Brandberg Part 1: Amis Gorge[END_REF]) and the discovery of what could be interpreted as evidence of ritual practices at Falls Rock Shelter (FLS, Brandberg; Kinahan 2018). The chronology of these Namibian rock arts rests mainly on stylistic analyses and comparison with the other Southern African rock arts [START_REF] Kinahan | Dâures, the burning mountain-issues of research and conservation in the Brandberg of Namibia[END_REF][START_REF] Kinahan | The rock art of /Ui-//aes (Twyfelfontein) Namibia's first World Heritage Site[END_REF][START_REF] Nankela | Rock art and landscape: An empirical analysis in the content, context and distribution of the rock art sites in Omandumba East and West, Erongo Region Namibia[END_REF][START_REF] Richter | Studien zur Urgeschichte Namibias[END_REF][START_REF] Richter | Prähistorische Felskunst und Besiedlung in Zentralnamibia[END_REF][START_REF] Richter | The giraffe people: Namibia's prehistoric art-ists[END_REF][START_REF] Richter | Rock art in North-Western Central Namibia: Its age and cultural background[END_REF]. Despite the attempts made by [START_REF] Conard | The feasibility of dating rock paintings from Brandberg, Namibia, with 14C[END_REF], no direct dating has so far been performed on Namibian rock art due to the scarcity of dating materials.

The Erongo Mountains, a circular volcanic and in-trusive rock complex of Jurassic to Cretaceous age [START_REF] Blümel | Der Erongo-Geowissenschaftliche beschreibung und deutung eines sudwestafrikanischen vulkankomplexes[END_REF]), located at the edge of the Namib Desert, are known to host numerous rock paintings and engravings attributed to LSA hunter-gatherers [START_REF] Breuil | Anibib & Omandumba, and other Erongo sites[END_REF][START_REF] Börner | Die Uberprufune der Schamanismus-Theorie anhand ausgewahlter Felsmalerien ausdem Erongo Gebirge, Namibia[END_REF][START_REF] Hollmann | A report on the rock paintings in the Erongo Mountain, Erongo Region: Karibib, Omaruru District, Namibia[END_REF][START_REF] Nankela | Rock art and landscape: An empirical analysis in the content, context and distribution of the rock art sites in Omandumba East and West, Erongo Region Namibia[END_REF][START_REF] Scherz | Felsbilder in Südwest-Afrika[END_REF][START_REF] Vallverdu | Nouvelles peintures du massif de l'Erongo S.W.A (Namibie), Drotskie Rock, Anibib I[END_REF]. The rock complex is regarded as a critical area for under-standing LSA hunter-gatherers' behavior in semi-arid environments. It contains numerous archaeological rock art sites where ochre fragments have been found in LSA contexts, and in association with rock art paintings (Online Resource 1). These sites include Fackelträger [START_REF] Richter | Studien zur Urgeschichte Namibias[END_REF][START_REF] Wendt | Preliminary report on an archaeological re-search program in south West Africa[END_REF], Etemba 2 [START_REF] Richter | Studien zur Urgeschichte Namibias[END_REF], Etemba 14 [START_REF] Richter | Studien zur Urgeschichte Namibias[END_REF], Rain Cloud, Giraffe Shelter, and Seal Shelter (Pleurdeau, personal communication), and Leopard Cave (LC -Pleurdeau et al. 2012; Table 1, Fig. 1). The LSA assemblages from the Erongo Mountains attest to the presence of human occupations all over the massif during the past 6,000 years. The LSA occupation levels have been divided into three technocomplexes-Wilton preceramic, Wilton ceramic, and post-Wilton [START_REF] Richter | The giraffe people: Namibia's prehistoric art-ists[END_REF]. They provided exceptional ochre-related assemblages in the form of numerous grinding and crushing stone tools with red residues on their surface, as well as hematite and "ochre stones". These artifacts raised the possibility of understanding the relationships between rock art paintings and human occupations and called for more excavations that seek to recover ochrerelated artifacts in their cultural contexts [START_REF] Richter | Studien zur Urgeschichte Namibias[END_REF][START_REF] Wendt | Preliminary report on an archaeological re-search program in south West Africa[END_REF]. The excavations carried out since 2014 at the rock art shelter of Leopard Cave led to the discovery of numerous artifacts that indicate intensive use of ochre. These diverse remains document a unique archaeological context within a painted shelter attributed to LSA hunter-gatherers in Southern Africa. They provide crucial insights into the cultural-economical behaviors of these communities and the origins of rock paintings in the region. This article presents the artifacts relating to ochre processing in Leopard Cave and makes some inferences about the sociocultural behaviors of the LSA populations who occupied the cave. We will also show the existence of intense ochre processing activity at the site.

Leopard Cave

Leopard Cave is a painted rock shelter located within a Cretaceous granitic spur. It lies in the Omaruru region in the northwestern part of the Erongo Mountains (Fig. 1b). Located on Omandumba West Farm, the shelter stands at an altitude of 1,256 m above sea level and 1.7 km south of the archaeological site of Fackelträger excavated by Wendt in the 1960s [START_REF] Richter | Studien zur Urgeschichte Namibias[END_REF][START_REF] Wendt | Preliminary report on an archaeological re-search program in south West Africa[END_REF]. Leopard Cave opens towards the south, facing the hills of the Erongo Mountains. The site consists of a small rock shelter of approximately 60 m 2 (about 8 m long), mostly covered by the overhang of a granite boulder (Fig. 2a-c).

Leopard Cave was discovered in 2006 during a pedestrian survey. The initial coring highlighted the archaeological potential of the site, and excavations took place over several years (2007-2009, 2011-2012, and 2014-2018). Currently, 16 m 3 of sediments have been excavated from nine squares (M6-7, N6-8, O7-8, and P7-8; Fig. 2d). The excavation revealed a 1.8-m-deep stratigraphic sequence documenting a succession of human occupations. The archaeological assemblage is comprised of quartz and basalt lithic artifacts, faunal remains, bone points, link shafts and needles, pendants, and ostrich eggshells (OES) beads, among others. All artifacts point to an LSA hunter-gatherers tradition that was based on opportunistic stone tool production [START_REF] Pleurdeau | Of sheep and men: Earliest direct evidence of caprine domestication in Southern Africa at Leopard Cave (Erongo, Namibia)[END_REF]. The archaeological assemblage also includes ochre fragments (n = 366), grinding and crushing stone tools (active and passive, n = 15), and ornamental artifacts with red pigment traces on their surface (OES beads, n = 61; bone pendants, n = 1; bone bead, n = 1). Following the discovery of numerous ochres and tools bearing pigment traces in 2014, the excavation of Leopard Cave was expanded towards the eastern wall of the shelter (squares O7-8, Fig. 2b) to investigate the possible connection between the archaeological assemblage and the rock art. In 2015, the excavation revealed red traces on the wall.

Stratigraphic Sequence

The sequence was subdivided into three stratigraphic complexes. There is evidence of some localized burrows cutting through the stratigraphic profiles. The archaeological materials found within these burrows are excluded in the present study. The upper complex I spans between -120 and -250 cm (Fig. 2d). Granitic "arena," silt, and an ash mixture of anthropic origin with abundant vegetable remains and charcoals are the main com-ponents of the nine subhorizontal layers of this complex, labeled from "a" to "j" (Fig. 2d and Table 2). The texture of the upper complex I derived from the powdered silts resulting from the breakdown of the granite. The presence of ash/charcoal and a large number of artifacts recovered from this stratigraphic complex demonstrate the existence of intense anthropic activities.

Complex II, between -250 and -280 cm, constitutes deliquescent granite that probably corresponds to a phase of collapse. The few artifacts discovered within these layers appear to be downward infiltration and infilling between the collapsed granitic blocks. Finally, complex III, starting from -280 cm, is made of an indurated arenaceous matrix, deprived of any ash or organic material. The substratum has not been reached, and a test-core indicates that at least 20 cm of artifact-bearing sediment remains unexcavated.

Chronology

The chronology of the Leopard Cave shelter strati-graphic sequence has been determined, based on 18 radiocarbon dates from charcoal samples. Table 2 lists all of these radiocarbon dates and provides information about their location at the site. Radio-carbon ages were calibrated using the OxCal 4.3 software (Bronk Ramsey 2009) with the SHCal13 calibration curve [START_REF] Hogg | SHCal13 southern hemisphere calibration, 0-50,000 years cal BP[END_REF]. The infilling was deposited between 13,600 ± 230 cal. BP (com-plex III, layer m) and 2,000 ± 150 cal. BP (complex I, layers c-e). The chronology tends to point to the existence of three significant periods of human occupations in complex I: between 5,700 and 3,200 cal BP (layer g), around 2,300-2,500 cal BP (layer f), and after 2,100 cal BP (layers c-e). Three dates obtained for samples SacA51308, SacA51309, and SacA51311 appear to be out of the chronological range of the site occupation. They are likely localized postdepositional events and resulted from intrusions from the upper layers.

Samples CA-DAT_AD36A and CA-DAT_AD36C provided important chronological data. The sample was obtained from a concretion covering the east wall of the shelter, a terminus ante quem for the covering of the wall by sediments. Archaeological layers located at the same levels, but deposited before the formation of this concretion, are dated to 3,200 cal BP. The C14 dates from CA-DAT_AD36A and CA-DAT_AD36C suggest 2,200 cal BP as the terminus ante quem for the covering of the wall by sediments.

Methods

Rock Painting Documentation

To study the parietal paintings and red traces on the walls of Leopard Cave, we photographically documented the walls and roof of the shelter with a Nikon D3300 with 105 mm focal distance. These pictures were then treated with Dstretch® [START_REF] Harman | Digital enhancement of pictographs from Baja California[END_REF], according to the method published by Le [START_REF] Le Quellec | Dstretch® et l'amélioration des images numériques: Applications à l'archéologie des images rupestres[END_REF]. Descriptions and analysis of these paintings can be found in [START_REF] Nankela | Rock art and landscape: An empirical analysis in the content, context and distribution of the rock art sites in Omandumba East and West, Erongo Region Namibia[END_REF] and [START_REF] Mauran | First in situ pXRF analyses of rock paintings in Erongo, Namibia: Results, current limits and prospects[END_REF].

Ochre Description

Archaeological pieces were first observed visually be-fore any treatment to evaluate their fragility and the possibility of washing them. The washing was per-formed with deionized water and ultra-sonication for 3 min for the hardest pieces. Only deionized water was used for the weaker ones, and a few were not cleaned at all in order not to destroy them. Once cleaned, the objects were observed with a binocular microscope (LEICA), and photos were taken with a Nikon D3300 with 105 mm focal distance. The description of the samples is presented & Granulometry of the block: estimated from the ob-servation of the block and described as being be-tween fine and coarse grain size & Block luster: description of the luster (metallic, submetallic, greasy, or no luster) & Presence of inclusion: inclusion description from binocular microscope observations of the block & Magnetization: estimated from a magnet test be-tween low (no reaction to a magnet) to high (strong reaction to a magnet)

These observations and descriptions permitted us to assess the diversity of the ochre found at Leopard Cave.

Anthropic Modification of Ochre Fragments

The experimental studies performed on ochre allowed inferences to be made on the existence and nature of anthropogenic modifications [START_REF] Dayet | Matériaux, transformations et fonctions de l'ocre au Middle Stone Age: le cas de Diepkloof Rock Shelter dans le contexte de l'Afrique australe[END_REF][START_REF] Hodgskiss | Identifying grinding, scoring and rubbing use-wear on experimental ochre pieces[END_REF][START_REF] Rifkin | Processing ochre in the Middle Stone Age: Testing the inference of prehistoric behaviours from actualistically derived experimental data[END_REF][START_REF] Rosso | Patterns of change and continuity in ochre use during the late Middle Stone Age of the Horn of Africa: The Porc-Epic Cave record[END_REF][START_REF] Salomon | Les matières colorantes au début du Paléolithique supérieur: sources, transformations et fonctions[END_REF].

After visual examination, we classified the ochre fragments from Leopard Cave into two groups: unmodified and possibly modified. The modifications were considered according to the presence of striations, facets, fracturing edges, polished surfaces, and flake scars. According to the previous works of Hodgskiss (2010) and [START_REF] Rifkin | Processing ochre in the Middle Stone Age: Testing the inference of prehistoric behaviours from actualistically derived experimental data[END_REF], we divided the potential anthropic modifications into two main groups: fragmentation and grinding. However, as no experimental study has been carried out on pure iron oxides or single fragmentation scars, we considered all the fragmentation scars as potential traces of anthropic modifications. These observations were coupled with the ones made on grinding and crushing tools, all stone items that have been intentionally modified through the pounding and grinding of other materials [START_REF] Dubreuil | Ground stones: A synthesis of the use-wear approach[END_REF][START_REF] Ebeling | The archaeology of the daily grind: Ground stone tools and food production in the southern Levant[END_REF][START_REF] Hayes | Learning from blind tests: Determining the function of experimental grinding stones through use-wear and residue analysis[END_REF]). The two anthropic modifications are described below.

1. Fragmentation aims at decreasing the volume of the blocks. It can be achieved through various actions: knapping, pounding, or crushing. These actions leave distinct marks on the blocks. Knapping, pounding, and crushing are often continuous actions to reduce the initial blocks into small shards and pigment powder [START_REF] Dayet | Matériaux, transformations et fonctions de l'ocre au Middle Stone Age: le cas de Diepkloof Rock Shelter dans le contexte de l'Afrique australe[END_REF][START_REF] Salomon | Les matières colorantes au début du Paléolithique supérieur: sources, transformations et fonctions[END_REF]. The small shards that were not reduced to powder bear traces of "fresh" sharp edge and "fresh" fracturing surfaces. Traces on the tools used to crush and grind are more evident as they correspond to percussion pits, and the saddle shape of the grinding slabs bear red residues on their surface. Knapping performed on ochre leaves scar traces, although these are sometimes hard to observe [START_REF] Henshilwood | Engraved ochres from the Middle Stone Age levels at Blombos Cave, South Africa[END_REF][START_REF] Salomon | Les matières colorantes au début du Paléolithique supérieur: sources, transformations et fonctions[END_REF]). 2. Grinding aims at shaping, altering the surface of the blocks , and producing pigment powder [START_REF] Henshilwood | Engraved ochres from the Middle Stone Age levels at Blombos Cave, South Africa[END_REF][START_REF] Hodgskiss | Identifying grinding, scoring and rubbing use-wear on experimental ochre pieces[END_REF][START_REF] Rifkin | Processing ochre in the Middle Stone Age: Testing the inference of prehistoric behaviours from actualistically derived experimental data[END_REF][START_REF] Salomon | Les matières colorantes au début du Paléolithique supérieur: sources, transformations et fonctions[END_REF]. Grinding use-wear is more evident on ochre fragments than traces of fragmentation. It consists of facets and multiple groups of parallel striations on the surface of both the ochre piece and the grindstone on which the blocks were rubbed. On the tools, ochre grinding use-wear patterns mainly consist of red tint, ochre grain residues, and leveling or smoothing of the microrelief on the active surface of the tool [START_REF] Hayes | Learning from blind tests: Determining the function of experimental grinding stones through use-wear and residue analysis[END_REF]). Other possible anthropic modifications consist of ochre thermic treatment [START_REF] Dayet | Matériaux, transformations et fonctions de l'ocre au Middle Stone Age: le cas de Diepkloof Rock Shelter dans le contexte de l'Afrique australe[END_REF][START_REF] Pomiès | TEM observa-tions of goethite dehydration: Application to archaeological samples[END_REF][START_REF] Salomon | Stratégies spécialisées d'acquisition de pigments rouges durant le châtelperronien de la grotte du renne à Arcy-sur-Cure (Yonne, France)[END_REF]. Only the archaeological context allows the differentiation of intentional treatment from accidental or postdepositional heating [START_REF] Salomon | Selection and heating of colouring material in the Mousterian level of Es-Skhul (c. 100,000 years BP, Mount Carmel, Israel)[END_REF][START_REF] Salomon | Solutrean and Magdalenian ferrugineous rocks heat treat-ment: Accidental and/or deliberate action[END_REF][START_REF] Wadley | Post-depositional heating may cause over-representation of red-coloured ochre in stone age sites[END_REF]). The large charcoal beds and the extensive number of heat-exploded lithics found at Leopard Cave prevent us from considering the potential thermic treatment intended for the ochre fragments at the site.

Description of Ochre Residues on Artifacts

The residues on artifacts were described according to the methodology proposed by [START_REF] Pradeau | Lesmatières colorantes au sein des systèmes techniques et symboliques au Néolithique (VIe et Ve millènaires BCE) dans l'arc liguro-provençal[END_REF]. All tools and ornaments were first observed with the naked eye to spot the presence of red residues and determine the part of the artifact on which they are present. All artifacts with residues on one of their surfaces were documented through various photographs with a Nikon D3300 with 105 mm focal distance. To enhance the visibility of the red residues present on the tools, the pictures were treated with Dstretch® [START_REF] Harman | Digital enhancement of pictographs from Baja California[END_REF]. All pictures were treated with the YRD filter. We then documented the presence of pits, smoothed edges, striations, and their relations with the red residues found on these artifacts.

Results

The Parietal Pigment Residues: Red Representations and Their Weathering

Eastern and northern walls of Leopard Cave bear red parietal representations or pigment traces (Figs. 2b and3). Differential erosion and weathering caused large granitic slabs to detach from their bedrock. Paintings seem to have been performed after the collapse of these large granitic slabs. Today, these representations are all located in the lowest parts of the walls. But given the recent sedimentation experienced in the shelter, the former surface levels must have been much lower, placing the paintings at about the eye level during the LSA occupations.

Twelve figures and one area of diffuse red flat tint have been recorded and described [START_REF] Nankela | Rock art and landscape: An empirical analysis in the content, context and distribution of the rock art sites in Omandumba East and West, Erongo Region Namibia[END_REF]). Among the 12 motifs identified, four are anthropomorphic, while four are zoomorphic (a headless giraffe, an antelope, a duiker, and a giraffe head). Another four figures are classified as indeterminable. All paintings exhibit fine-line appearance, a characteristic of the rock paintings in the Erongo region (for example, see the back legs of the antelope displayed in Fig. 3b; Nankela 2017; Richter 1991). Only red monochromes were observed at this site.

Most of the paintings are in a poor state of conservation, as a result of natural weathering and anthropogenic activities resulting in dust coating. Substantial black residues covering the ceiling prevent us from assessing the possibility for the presence of paintings in this part of the cavity. Only the headless giraffe is still clearly visible (Fig. 3a), while all other paintings vanished under white crusts, such as the back legs of the antelope (Fig. 3b), or as the result of both water and sandy wind erosions-the headless giraffe (Fig. 3c).

The 2015 excavation of the subsquares lying next to the eastern wall (squares P7-P8) allowed us to clear the wall from the sediment covering it, and red traces were observed on the wall (Fig. 3f-h) between levels at z = -162 cm (27 cm below the surface) and z = -189 cm (54 cm below the surface) (Fig. 3f). These red traces could have resulted from the natural red tint of the granite, the presence of vanished red painting, or the leaking of pigments from wall sections above this area. The in situ pXRF analyses confirmed that the origin of the red tint was from the anthropogenic presence of iron pigment [START_REF] Mauran | First in situ pXRF analyses of rock paintings in Erongo, Namibia: Results, current limits and prospects[END_REF].

Ochre Fragments and Pigment Traces on the Archaeological Materia

Ochre fragments (n = 366), tools (grinding slabs and handstones, n = 15), and ornaments (OES, bone beads, and bone pendant) bearing traces of pigments were discovered in stratigraphic complex I at the bottom of the painted wall (squares O/P; Fig. 2b). The presence of a grinding slab (T-LC-01) and a handstone (T-LC-07)-both bearing traces of use and an ochre piece with an abraded surface (LC-030, Fig. 4a)-are convincing ev-idence of the mechanical transformation of ochre at the site.

Nature of the Ochre Fragments

The blocks of raw ochre that we studied were recovered from the 2014-2018 excavations. They are 366 pieces, representing a total mass of about 1.1 kg. They could be divided into two main macroscopic groups: black metallic iron oxides and red ferruginous rocks (Table 3 and Fig. 5). The first group corresponds to wellcrystallized iron oxides and includes 171 elements for a total weight of 0.7 kg, representing 47% of the collection in the number of samples and 68% in mass. The pieces present a gray to black nodule aspect with a submetallic to metallic brilliance. They have the attributes of high cohesion and hardness with a homogenous matrix and a massive structure (Fig. 5). Their external surface is smooth without any sharp edges but with a metallic glow, as exemplified in samples LC-047, LC-049, LC-189, and LC-301 in Fig. 5. Within the matrix, various inclusions are present. The predominant ones correspond to millimetric to centimetric quartz inclusions.

The second group is made up of different ferruginous rocks and comprises 195 specimens (53% of the total number) and totaling 0.4 kg (36% in mass). The characteristics of these pieces are the following: red to yellow hues, no brilliance, medium to low cohesion and hardness, and heterogeneous matrix (Fig. 5). How-ever, this ferruginous rock group also comprises pieces of various textures ranging from granular (LC-255, LC-283, LC-248, LC-030) to well-stratified (LC-298) or heterogeneous (Fig. 5). Therefore, this group comprises ferruginous sandstones (n = 65), banded ironstone (n = 59), ferruginous mudstones (n = 26), and other ferruginous altered rocks (n = 45). Since we did not observe any difference in their spatial distribution or potential treatment, we decided to gather them into a single group of ferruginous rocks. Potential Anthropic Modifications of the Ochre Fragments At Leopard Cave, 63% of the iron oxides blocks (n =109) exhibit potential marks of anthropogenic fragmentation in the form of fracturing surfaces and flake scars. Fracturing surfaces are the most prominent marks and correspond to net breaks of the pieces, such as those exemplified in Fig. 5 for LC-126, LC-200, LC-233, and LC-270. Flake scars were also identified through the presence of impact points (LC-200 and LC-270 on Fig. 5). The anthropic origin of these potential fragmentation traces is reinforced by the discovery of numerous small sherds of ochre (less than 1 mm), close to the blocks with those scars.

Among the ferruginous rocks, only three pieces out of 195 have striated facets (LC-030, LC-265, and LC-266; Fig. 5). While LC-030 exhibits only one facet of abrasion (Fig. 5), LC-265 and LC-266 exhibit several sides that bear four and two facets of abrasions with unidirectional microstriations (Fig. 5). As these flat surfaces do not exhibit sharp grooves or extremely pronounced microstriations, they are consistent with the grinding procedure of ochre, as published by [START_REF] Hodgskiss | Identifying grinding, scoring and rubbing use-wear on experimental ochre pieces[END_REF]. Other possible use-traces consisted of fragmentation marks on numerous pieces (n = 160), as exemplified by LC-298 (Fig. 5). Crushing and grinding tools of Leopard Cave were divided into two groups, according to the morphological classification system of [START_REF] Wright | A classification system for ground stone tools from the prehistoric Levant[END_REF]: (1) grinding slabs (passive tools, n = 6) and ( 2) handstones (active tools, n = 9). Figures 4 and6 present some of these active and passive tools. Grinding slabs are the largest tools of the Leopard Cave assemblage, measuring at least 20 cm long. All six grinding slabs with red residues have an active face identifiable by their smoothed microrelief and flattened aspect (e.g., T-LC-01 and T-LC-02; Figs. 4 and6) and their saddle shape (e.g., T-LC-03; Figs. 4 and6). They are made either from granite (n = 4) or basalt (n = 2), both readily available in the vicinity of Leopard Cave. Five of the slabs appear intact (e.g., T-LC-01 and T-LC-02), while one is broken on its active surface (T-LC-03). One of the basaltic grinding slabs, T-LC-02, has been shaped on one of its pas-sive surfaces by knapping (Fig. 6a). High concentrations of red residues are found on these grinding slabs, suggesting their use to produce pigment pow-der, either by grinding or by fragmentation.

The grinding slabs can be divided into two groups: the grinding slabs with a red tint on their active surfaces and the ones solely presenting red residues on the edges of their active surfaces.

Within the first group of grinding slabs (n = 4), the active surface presents a clear to diffuse red tint, and red ochre grains are visible macroscopically in the smoothed asperities of the granite and basalt slabs (Figs. 4 and6). The presence of a red-tinted smoothed active surface, bearing grains of ochre in its asperities, is characteristic of ochre processing by grinding [START_REF] Ebeling | The archaeology of the daily grind: Ground stone tools and food production in the southern Levant[END_REF][START_REF] Ebeling | The archaeology of the daily grind: Ground stone tools and food production in the southern Levant[END_REF][START_REF] Hayes | Learning from blind tests: Determining the function of experimental grinding stones through use-wear and residue analysis[END_REF]. As for the second group (n = 2), the smoothed active surface did not present any clear red tint, and red residues could only be spotted at the edges of this surface (Figs. 4 and6). The red residues present on these artifacts might result from incidental contact with ochre pieces or ochred surfaces such as human skin or animal hide. Unfortunately, no other material was identified on the active surface, preventing us from determining the use of these stone tools.

Handstones are smaller tools, measuring around 10 cm long and all made of basalt. All these nine active tools with red residues present a single convex smoothed side with some pitting marks, corresponding to the active surface of the tools (Figs. 4 and6b). Although all have some red residues on at least one of their lateral passive surfaces, only a few (T-LC-05, T-LC-06, T-LC-08) exhibited red tint or red ochre residues within the smoothed pits and microstriations on their active surface. These wear traces demonstrate the use of some of the tools to process ochre. Handstone T-LC-06 is broken but is still identifiable, thanks to the presence of an active surface covered by red residues and percussion pits. Its breakage might be related to the intensive crushing of hard materials such as iron oxides. The absence of residues on the active surfaces of some of the handstones could be due to the reuse of these tools to grind other materials, such as plants, or due to low adhesion of the ochre on the surface. The residues found only on the lateral faces could be the result of contact with an ochre-stained tool, an ochred artifact, or human skin. The modified ochre pieces, grinding tools bearing red pigment traces, a modified ochre piece, and the crushing and grinding tools with red residues over their active surface (4 grinding slabs and 4 handstones) all serve as evidence of the on-site mechanical transformation of ochre to produce pigment powder.

Ochre Residues on Ornaments

The artifacts with red residues on their surfaces are not only restricted to crushing and grinding tools at Leopard Cave but also include ornamental pieces, especially beads and pendants (n = 63). Schists, ostrich eggshells, bone shafts, and bone ornaments were found at Leopard Cave [START_REF] Pleurdeau | Of sheep and men: Earliest direct evidence of caprine domestication in Southern Africa at Leopard Cave (Erongo, Namibia)[END_REF]), but red residues are solely observed on ostrich eggshell (OES) beads (n = 61), one bone bead, and one bone pendant. The OES beads diameter lies between 3 and 7 mm, and there are two categories of these based on the color: white to cream, and gray to black (Fig. 7). Among the 61 OES beads with red residues, the first group, comprising 57 pieces, is the most prominent. Only a few of them have small areas covered by thick layers of red residues (n = 12). These areas are located on the lateral side (OES-LC-002, Fig. 7), in the central perforation (OES-LC-313, Fig. 7), and on inner and outer sides (OES-LC-305, OES-LC-313, OES-LC-313, Fig. 7) of the beads. On a few beads (e.g., OES-LC-305), specific use-wear patterns could be identified (Si Ammour 2016). These consist of light depressions filled with red residues on both sides.

There is also an ornate bird bone tube bead measur-ing 5 cm long and 0.5 cm in diameter with 15 notches of ca. 1 mm deep (Fig. 7). These 15 notches present similar profiles and manufacturing techniques. They most probably were made with the same tool during a single episode. It is similar to the bone tube beads discovered at other Namibian archaeological sites (Vogelsang and Eichorn 2011). Unfortunately, the animal species to which this bone belongs could not be identified, as it is only a fragment of diaphysis with no other diagnostic features. Eight other undecorated bird bone fragments were found in the same layer, again too fragmented to be assigned to one taxon. A few red residues are still trapped within the notches. These red residues consist of packs of granular red clay, mixed with micrometric angular hematite particles. Tiny red unidirectional striations can be seen on these bone fragments. These tiny striations are not deep and represent hematite particles barely visible with an optical microscope; they could potentially be the result of bone polishing with some ochre.

The red residues found on the beads and pendant could be the result of the coloring of the beads or taphonomic processes. But as for most of the beads, the red residues are sporadic. Therefore, it is more likely that they resulted from indirect coloration due to contact with a colored surface, such as a colored string, cloth, or body. That is, the red residues on the beads could have derived from the ochre used to paint body or clothes, both possibly connected to identity markers [START_REF] Rigaud | The way we wear makes the difference: Residue analysis applied to Mesolithic personal ornaments from Hohlenstein-stadel (Germany)[END_REF]Vanhaeren andd'Errico 2003, 2005;[START_REF] Vanhaeren | Middle Paleolithic shell beads in Israel and Algeria[END_REF]. 8 sum up the distribution of the ochre fragments and associated grinding stones, beads, and quartz and basalt lithic industries in the stratigraphic complexes and layers. The artifacts were recovered from complex I in layers g and f, spanning from -125 to -260 cm (Fig. 8). Complex II and the upper part of complex III are almost sterile of archaeological remains. Layer f presents a few ochre pieces, some showing possible anthropogenic modifications, and there are also tools and beads with red residues. However, the highest concentration of artifacts is in the "oldest" layer g, located between -185 and -250 cm (Fig. 8 and Table 3). This is also where the decorated bone bead was found. While layer f has delivered one ceramic sherd, possibly due to sediment disturbance, no ceramic sherd was recovered from layer g. When considering the mass distribution of ochre in this stratigraphic complex, it is noteworthy that an iron oxide block weighing 310 g (LC-130) biased this distribution. Indeed, most of the ochre fragments weighed less than 10 g, with a median weight of 0.8 g. This low value reflects the high fragmentation of the ochre assemblage at Leopard Cave. Moreover, in layer g, potential anthropogenic modifications were identified in over 73% (220 out of 302) of the ochre fragments recovered (Table 3), confirming the intensive ochre exploitation at the site.

Both kinds of ochre fragments-iron oxides and ferruginous rocks-were recovered in the stratigraphic units f and g, with no apparent time differentiation. However, rich iron oxides are more abundant in layer g than in f, although both layers have delivered similar frequencies of lithic industries and faunal remains (Table 3). This difference could indicate either a change of activities performed at the site between the two occupation phases, or a shift in the deposition rate. Nevertheless, from the data gathered, ochre-processing ap-pears to have been an important activity during the occupation phase corresponding to the two archaeological layers.

According to the chronology of the stratigraphic sequence, layer g is dated between 5,700 and 3,000 BP, despite the unexpected dates of ca 2,100 BP from three charcoal samples (Table 2). Postdepositional activities were most probably responsible for this unexpected young age. Hence, the 2,100 BP date must be considered as the minimum age of the layer and most of the materials above it. This should also be considered as the minimum age of the oldest rock paintings at Leopard Cave (see further discussions below).

Discussion

The technical processes for the production of pigments seem to have five main steps: (1) exploitation/collection of raw materials (ochre) and their subsequent storage;

(2) transformation of ochre for the production of color-ing powders;

(3) storage of the ochre powder; (4) pos-sible mixing with binders and extenders; and (5) use of the powder/mixture [START_REF] Dayet | Matériaux, transformations et fonctions de l'ocre au Middle Stone Age: le cas de Diepkloof Rock Shelter dans le contexte de l'Afrique australe[END_REF][START_REF] Rifkin | Assessing the efficacy of red ochre as a prehistoric hide tanning ingredient[END_REF][START_REF] Salomon | Les matières colorantes au début du Paléolithique supérieur: sources, transformations et fonctions[END_REF]. At Leopard Cave, at least three of this five-step chaîne opératoire have been identified: collection and storage of raw materials, ochre transformation for the production of coloring powders, and their use.

Collection and Storage of the Raw Material

Leopard Cave is not near a natural outcrop of ochre, and these materials could not have been formed from pedogenetic alterations. Hence, the large number of ochre fragments found at the site (n = 366) indicates that the raw materials were collected from elsewhere and stored at the site. The diversity of ochres recovered, with a large collection of ferruginous rocks and iron oxides, could be the result of an opportunistic procurement strategy or an important activity of ochre trade from distinct outcrops, as hypothesized by [START_REF] Steele | Varsche Rivier 003: A Middle and Later Stone Age site with Still Bay and Howiesons Poort assemblages in Southern Namaqualand, South Africa[END_REF]. In the case of an opportunistic procurement strategy, ochre might have been collected during expeditions for other vital goods, with minimum effort to extract them and with a few materials obtained at a time [START_REF] Couraud | Pigments utilisés en Préhistoire. Provenance, préparation, mode d'utilisation[END_REF], cited by Salomon 2009). The raw material collected came from different places. But these outcrops must be mostly local as they should fall within the region covered by hunter-gatherer populations for their economic activities. In such a procurement strategy, it seems unlikely that ochres would have been collected and transported over very long distances. The fact that many blocks of iron oxides found at Leopard Cave exhibit a smooth outer surface, without any scars from extraction (Fig. 5), supports the hypothesis of an opportunistic collection of the iron oxides at their original ore outcrops. At Leopard Cave, the lithic industries are made mainly of quartz and basalt, also supporting an opportunistic strategy for the use of local raw materials for tool manufacture [START_REF] Pleurdeau | Of sheep and men: Earliest direct evidence of caprine domestication in Southern Africa at Leopard Cave (Erongo, Namibia)[END_REF].

As iron oxides and ferruginous rocks might have had different values and natural availability near Leopard Cave, the efforts undertaken to collect these various ochres might have been different. The provenience study of the different ochre fragments recovered at Leopard Cave could help us to understand the mobility pattern of the LSA communities in the area, the territory they exploited for raw materials, and the efforts expended to collect these ochre fragments [START_REF] Dayet | Matériaux, transformations et fonctions de l'ocre au Middle Stone Age: le cas de Diepkloof Rock Shelter dans le contexte de l'Afrique australe[END_REF]). It will also help us to understand the possible changes in ochre procurement strategies during the Lat-er Stone Age, a topic pioneered by [START_REF] Bernatchez | Geochemical characterization of archae-ological ochre at Nelson Bay Cave (Western Cape Province), South Africa[END_REF] at Nelson Bay Cave (Western Cape, South Africa). The provenience study of ochre promises to bring new in-sights on the economic behaviors of the LSA populations who occupied Leopard Cave, as well as their social organization.

Ochre Transformations

The presence of several grinding slabs (N = 6) and handstones (N = 9), as well as the occurrence of red residues and use-wear (e.g., scars) on their surface, demonstrate the intensive pigment processing at Leop-ard Cave during the LSA. These grinding tools might have also been used to grind other materials such as plants, explaining the conservation of red residues in anfractuosities located on the passive faces of the tools. Our observation of the assemblage revealed two distinct chaînes opératoires for producing the pigment powder: fragmentation and grinding, as described above. The recovery of small fragments (less than 1 mm) and larger ochre blocks testify to the fragmentation process at the site. The presence of fracturing surfaces on different types of ochre indicates that fragmentation was a com-mon technique for ochre powder production at the Leopard Cave. This is in agreement with Southern African ethnological data, according to which grinding and pounding are the usual treatments of ochre [START_REF] How | The mountain bushmen of Basutoland[END_REF][START_REF] Rudner | Khoisan pigments and paints and their rela-tionship to rock paintings[END_REF]). The facets observed on three ferruginous rocks also relate to the grinding technique (Fig. 5). Traces of this technique were only observed on ferruginous rocks that are of soft materials and not on harder iron oxide blocks, an indication of differential ochre treatments based on the degree of hardness. The question then is whether the apparent differential ochre treatment was due to anthropogenic choices or related to a taphonomic bias such as gelifraction and intense heating? The experimental tests on geological iron oxides lead us to support the idea of anthropogenic choice. We noticed that the fragmentation method for iron oxides was based on their hardness. Such a differential treatment raises further questions. Why were all ochres not treated the same way and pounded? The answer to this question may relate to whether the choice to grind some pieces was linked to some kind of symbolic consideration instead of being purely oriented towards technical needs.

Ochre Uses at Leopard Cave

The ochre-related artifacts at Leopard Cave could be connected to various cultural, social, technical, and economic purposes, not all linked to the rock paintings present on the site or in the surroundings [START_REF] Cristiani | Residue analysis and ornament suspension techniques in prehistory: Cyprinid pharyngeal teeth beads from Late Mesolithic burials at Vlasac (Serbia)[END_REF][START_REF] Dayet | Beads, pigments and early Holocene ornamental traditions at Bushman rock shelter, South Africa[END_REF][START_REF] Vanhaeren | Grave goods from the Saint-Germain-la-Riviere burial: Evidence for social inequal-ity in the upper Palaeolithic[END_REF][START_REF] Orton | Later Stone Age ostrich eggshell bead manufac-ture in the Northern Cape, South Africa[END_REF]). Therefore, the sequence of occupations found at Leopard Cave offers the opportunity to examine whether there were changes in the production and use of the pigments over time.

Some of the ochre fragments and ochre-related arti-facts were found just at the bottom of the painted wall (Fig. 3). And, the minimum age for creating the paintings is consistent with the radiocarbon ages for the layers where the ochre-processing artifacts were found (Table 2). It is tempting, therefore, to say that the ochres were likely used to create the paintings in the shelter. Given the large numbers of rock painting sites around Leopard Cave, it is also possible that ochres found at Leopard Cave were used to produce paintings at some of these other sites [START_REF] Breuil | Anibib & Omandumba, and other Erongo sites[END_REF][START_REF] Börner | Die Uberprufune der Schamanismus-Theorie anhand ausgewahlter Felsmalerien ausdem Erongo Gebirge, Namibia[END_REF]Hollman and Steyn 2003;[START_REF] Nankela | Rock art and landscape: An empirical analysis in the content, context and distribution of the rock art sites in Omandumba East and West, Erongo Region Namibia[END_REF][START_REF] Scherz | Felsbilder in Südwest-Afrika[END_REF]). It appears that ochres were primarily used for their tinting strength and might have conveyed a magi-cal value, as mentioned in the literature for both ethno-graphic and archaeological contexts [START_REF] Bleek | Specimens of Bushman folklore[END_REF][START_REF] How | The mountain bushmen of Basutoland[END_REF][START_REF] Rudner | Khoisan pigments and paints and their rela-tionship to rock paintings[END_REF][START_REF] Van Der Ryst | The Waterberg plateau in the northern province, Republic of South Africa, in the Later Stone Age[END_REF]. In bearing such a magical value, ochres should be considered as a precious raw material. Its treatment, therefore, followed specific steps, as described in [START_REF] Rudner | Khoisan pigments and paints and their rela-tionship to rock paintings[END_REF] review of ethnographic data. The fragmentation and grinding processes, identified at Leopard Cave, could relate to these steps. Identifying the nature of the ochre used to perform the rock paintings could bring new insights regarding rock art production at Leopard Cave and the surrounding area.

However, several other uses should be considered for ochre at Leopard Cave, given the presence of red residues on a wide range of archaeological materials. For example, the red residues present on the beads could have resulted from contact with body paintings, a well-known practice for both social and technical reasons in Southern Africa [START_REF] How | The mountain bushmen of Basutoland[END_REF][START_REF] Rifkin | Processing ochre in the Middle Stone Age: Testing the inference of prehistoric behaviours from actualistically derived experimental data[END_REF]Rifkin et al. 2015a, b;[START_REF] Rudner | Khoisan pigments and paints and their rela-tionship to rock paintings[END_REF]; ochred strings on which beads were glued; ochred strings on which the beads were arranged; or clothes on which ochred strings/beads were sewn [START_REF] Dayet | Beads, pigments and early Holocene ornamental traditions at Bushman rock shelter, South Africa[END_REF][START_REF] Vanhaeren | Thinking strings: Additional evidence for personal ornament use in the Middle Stone Age at Blombos Cave, South Africa[END_REF]. Ethno-graphic data about the ornaments used by !Kung huntergatherers from Botswana attest to the extensive use of OES beads, adhesive, and strings to form complex ornaments [START_REF] Marshall | The !Kung of Nyae Nyae[END_REF]. Authors have demonstrated the existence of similar personal ornaments within archaeological assemblages of LSA and MSA sites, at Bushman Rock Shelter [START_REF] Dayet | Beads, pigments and early Holocene ornamental traditions at Bushman rock shelter, South Africa[END_REF] and Blombos Cave, respectively [START_REF] Vanhaeren | Thinking strings: Additional evidence for personal ornament use in the Middle Stone Age at Blombos Cave, South Africa[END_REF]. At Leopard Cave, beads with red residues on their ventral and dorsal sides (e.g., OES-LC-313, OES-LS-314, and OES-LC-317; Fig. 7) could have been glued together to form rigid lines or ring-shaped ornaments. Beads with residues within their inner lateral sides could have been similarly arranged and glued on a string (e.g., OES-LC-303 and OES-LC-313). Likewise, the bone tube (O-LC-02) bead could have been part of a larger ornament arranged on a string. The red residues on the external sides of the beads may have resulted from contacts with an ochred body. In all cases, the red residues on the ornaments are indicative of the past cultural, social, and technical practices of ochre exploitation at Leopard Cave.

Indeed, body paintings and personal ornaments generally convey complex social information (Vanhaeren andd'Errico 2003, 2005;[START_REF] Vanhaeren | Middle Paleolithic shell beads in Israel and Algeria[END_REF][START_REF] Vanhaeren | Thinking strings: Additional evidence for personal ornament use in the Middle Stone Age at Blombos Cave, South Africa[END_REF][START_REF] Rigaud | The way we wear makes the difference: Residue analysis applied to Mesolithic personal ornaments from Hohlenstein-stadel (Germany)[END_REF]). They could be markers of status or individual/community identity in everyday life or during specific events of high symbolic importance [START_REF] Rudner | Khoisan pigments and paints and their rela-tionship to rock paintings[END_REF]. The use of ochre for body paintings possibly also served technical purposes, such as insect repellent or sun protection [START_REF] Rifkin | Processing ochre in the Middle Stone Age: Testing the inference of prehistoric behaviours from actualistically derived experimental data[END_REF]Rifkin et al. 2015a, b). All of these further highlight the difficulty of discussing ochre uses at an inhabited rock art site. This difficulty of interpretation is further intensified by other possible ochre uses that do not leave archaeological traces but are known from ethnographic studies (e.g., hide tanning; [START_REF] Kewanwytewa | Hopi moccasin making[END_REF][START_REF] Webley | Hideworking among descendants of Khoekhoen pastoralists in the Northern Cape, South Africa[END_REF]. Ethnographic data allow us to consider the existence of such use in LSA populations [START_REF] Blauer | African elegance[END_REF]), but the Leopard Cave ochres do not bear direct evidence for such use since treated skin, like most organic materials, are not preserved in the archaeological context.

Chronological Constraints

From a stylistic point of view, the paintings at Leopard Cave are similar to the other Namibian rock art paintings. Such monochrome fine-lines paintings are encountered in various sites in Namibia, especially at other excavated sites of the northwestern Erongo Mountain, such as Fackelträger [START_REF] Richter | Studien zur Urgeschichte Namibias[END_REF][START_REF] Wendt | Preliminary report on an archaeological re-search program in south West Africa[END_REF], Rain Cloud [START_REF] Breuil | Anibib & Omandumba, and other Erongo sites[END_REF], and Etemba [START_REF] Wendt | Preliminary report on an archaeological re-search program in south West Africa[END_REF]. The paintings found at Leopard Cave seem to be of the same cultural tradition as those of these other sites in the Erongo area [START_REF] Nankela | Rock art and landscape: An empirical analysis in the content, context and distribution of the rock art sites in Omandumba East and West, Erongo Region Namibia[END_REF].

Although archaeological raw blocks of ochres were found at Leopard Cave in levels ranging from -140 to -300 cm, their highest concentration was observed between -190 and -230 cm (Fig. 8). The latter corre-sponds to archaeological layers f and g, dated between 3,500 ± 100 cal BP (Beta-236964) and 2,000 ± 150 cal BP (SacA51308). The youngest date of these layers was obtained from a charcoal sample located near a grinding slab and a handstone showing red traces that might have been displaced vertically into older layers due to postdepositional biologic agents; for example, the localized burrows. The age obtained from it should be considered as the minimum age for the use of the in situ grinding slab and handstone.

The red pigment on the wall of the cave at levels previously buried under the sediment provides a terminus ante quem for the creation of some of the paintings. As demonstrated by [START_REF] Mauran | First in situ pXRF analyses of rock paintings in Erongo, Namibia: Results, current limits and prospects[END_REF], the red traces found on the wall are not from the stains of sediment; neither are they a natural coloration of the granite. Rather, they correspond to the anthropogenic use of iron oxide pigments. These traces of pigments on the wall are either the remains of a red painting that is completely altered or traces of weathered pigments from paintings drawn above (Fig. 3). Therefore, the dating of this archaeological layer to 2,100 ± 100 cal BP provides an age for the covering of these traces by sediments, not for the creation of the painting.

The present findings at Leopard Cave indicate a tradition of ochre processing between 3,500 and 2,000 BP, during the Wilton pre pottery period known at other Namibian sites for the extensive use of ochres [START_REF] Richter | Studien zur Urgeschichte Namibias[END_REF][START_REF] Richter | The giraffe people: Namibia's prehistoric art-ists[END_REF]. The highest number of ochre fragments was discovered in layer g, where no ceramic sherd was present (Fig. 8 and Table 3). This layer is dated between 3,100 and 5,100 cal BP, corresponding to the Wilton preceramic period [START_REF] Richter | The giraffe people: Namibia's prehistoric art-ists[END_REF]. These dates are similar to those obtained at other sites in the Erongo Mountains such as Fackelträger and Etemba [START_REF] Richter | Studien zur Urgeschichte Namibias[END_REF][START_REF] Wendt | Preliminary report on an archaeological re-search program in south West Africa[END_REF], Rain Cloud (Pleurdeau, personal communication), Striped Giraffe [START_REF] Sandelowsky | Supplementary report on the archaeological expedition of 1962 to the Erongo Mountains of South West Africa[END_REF], and Phillips Cave [START_REF] Martin | The test trench in the Phillips cave, Ameib, Erongo mountains, South West Africa[END_REF] in which archaeological ochres have also been recovered (Table 1, Fig. 1, and Online Resource 1). All of these confirm the existence of a long tradition of ochre processing in the Erongo Mountains, and more generally, in northcentral Namibia. Some of these were related to the execution of rock art paintings in the region. The minimum age of Leopard Cave paintings (2,100 ± 100 cal BP) is slightly younger than the minimum age obtained in the Brandberg at Amis 10/Riesenhöhle [START_REF] Breunig | Der Brandberg. Untersuchungen zur Besiedlungsgeschichte eines Hochgebirges in Namibia[END_REF][START_REF] Pager | The rock paintings of the Upper Brandberg Part 1: Amis Gorge[END_REF]), but it still falls in the pre pottery period proposed by [START_REF] Richter | Studien zur Urgeschichte Namibias[END_REF][START_REF] Richter | The giraffe people: Namibia's prehistoric art-ists[END_REF].

Based on stylistic considerations of the rock art paintings and the archaeological artifacts recovered from the Namibian painted sites, [START_REF] Richter | Studien zur Urgeschichte Namibias[END_REF][START_REF] Richter | The giraffe people: Namibia's prehistoric art-ists[END_REF] proposed 6,000-1,000 cal BP as the main period for the creation of the Namibian paintings. He divided this into two periods: pre pottery (6,000-2,000 cal BP) and post pottery (2,000-1,000 cal BP). According to the assemblages recovered at different rock art sites, the pre pottery stage corresponds to the period with most intensive activities for ochre processing and the execution of most of the Namibian LSA rock art [START_REF] Richter | Studien zur Urgeschichte Namibias[END_REF][START_REF] Richter | The giraffe people: Namibia's prehistoric art-ists[END_REF]. The sole terminus ante quem, coming from the Brandberg site of Amis 10 (Riesenhöhle), falls with-in this period. Indeed, at this site, the exfoliated fragment of paintings derived from a layer dated to 2,760 ± 50 cal BP [START_REF] Breunig | Der Brandberg. Untersuchungen zur Besiedlungsgeschichte eines Hochgebirges in Namibia[END_REF][START_REF] Pager | The rock paintings of the Upper Brandberg Part 1: Amis Gorge[END_REF]. The remaining challenge is to more securely link the rock art paintings of Leopard Cave in relation to the ochre of the archaeological contexts.

Future Directions

Leopard Cave is unique because of the documentation of the different chaîne opératoire for ochre processing and usage (raw blocks, tools bearing red residues, colored OES beads, and paintings) in the archaeological contexts. Although severely altered, the paintings at the cave still present characteristics similar to the rock paintings already studied in western Namibia [START_REF] Breuil | Anibib & Omandumba, and other Erongo sites[END_REF][START_REF] Nankela | Rock art and landscape: An empirical analysis in the content, context and distribution of the rock art sites in Omandumba East and West, Erongo Region Namibia[END_REF][START_REF] Scherz | Felsbilder in Südwest-Afrika[END_REF][START_REF] Vallverdu | Nouvelles peintures du massif de l'Erongo S.W.A (Namibie), Drotskie Rock, Anibib I[END_REF]. Their alteration is mainly caused by water leakages that led to the dissolution of the pigments and the formation of authigenic crusts identified as calcium sulfate, such as gypsum and calcium oxalate [START_REF] Mauran | First in situ pXRF analyses of rock paintings in Erongo, Namibia: Results, current limits and prospects[END_REF]. These leakages all originate from various cracks found in the granite bedrock. Experiments are currently in progress to radiocarbon date the alterations covering the paintings at Leopard Cave, as one of the steps needed to overcome some of the chronological constraints in the present study (Dumoulin et al. in press). The ongoing effort to correlate the chemical attributes of the pigments in the rock paintings and on the archaeological tools promises to shed more light on the processes for the creation of the paintings and their subsequent alterations. Indeed, if the coloring agents discovered in the archaeological layers and the rock paintings correlate in terms of chemical composition, this would provide strong evidence for indirect dating of the rock paintings [START_REF] Beck | Non-destructive provenance differ-entiation of prehistoric pigments by external PIXE[END_REF][START_REF] Bednarik | The dating of rock art: A critique[END_REF][START_REF] Lebon | Prehistoric pigment characterization of the Abri Pataud rock-shelter (Dordogne, France)[END_REF][START_REF] Lebon | Enhanced identification of trace element fingerprint of prehistoric pigments by PIXE mapping[END_REF][START_REF] Lebon | Characterization of painting pigments and ochers associated to Hoabinhian ar-chaeological context at the rock paintings site of Doi Pha Kan (Thailand)[END_REF]. Research about this correlation is partly hardened by the semantic discrepancies of the term "ochre" for the different actors involved in this research. Such issue calls for moving to less problematic terms, carefully selected in agreement with all disciplines involved in the study of these materials.

There is also an ongoing study of the microsamples of the rock art paintings, red residues found on the tools, and the ochre fragments using scanning electron microscopy (SEM), particle-induced X-ray emission (PIXE), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). These analyses will pro-vide new insights on the technical processes for the production and use of pigments at Leopard Cave (see [START_REF] Hahndiek | Of pigments and paint: Quantifying ochre and rock art in the Cederberg (Western Cape, South Africa)[END_REF][START_REF] Hughes | A preliminary study of ochres and pigmentaceous materials from KwaZulu-Natal, South Africa: Towards an understanding of San pigment and paint use[END_REF]. We plan to include other Erongo LSA rock art sites in our future studies. These include Rain Cloud, Giraffe Shelter, and Seal Shelter (Table 1, Fig. 1), where test pits already show the promise of documenting pigment production activities. This multisite study will provide critical in-sights into the pattern of LSA population mobility, their interactions with the environment, and the values they placed on ochre.

Conclusion

Our study presents an exceptional archaeological assemblage connected to the processing of ochres at Leopard Cave in the Erongo Mountains, Namibia. The rich-ness of this assemblage derives from the number of blocks of raw ochre and the traces of red residues on artifacts, tools, and ornaments. There is strong evidence for a long tradition of ochre processing at the site of Leopard Cave, and this was possibly connected to the rock paintings at the site. At least two distinct chaînes opératoires for ochre processing were documented, and these were possibly used for various purposes, including the creation of rock paintings, body painting, and abrading agents. The study also presents a new chronological framework for the rock art paintings at Leopard Cave, showing that the paintings were rendered between 3,600 and 2,000 cal BP, during the pre pottery LSA period. This study is part of the renewed rock art studies in Southern Africa. It paves the way for new ochre and rock art analyses, to understand the technological, sociocultural, and chronological development of LSA rock art and ochre usage in the Erongo Mountains of Namibia. The study also calls for more investigations on ochre uses at other Southern African LSA rock art sites.

  Fig. 1 Southern African rock art sites with archaeological ochre assemblage: a regional context; b Erongo Mountains (Namibia)

Fig. 2

 2 Fig. 2 Leopard Cave (a), showing (b) excavated squares within the shelter-red lines indicate the location of the paintings in the shelter; (c) shelter profile; and (d) stratigraphic sequence of cut 6/7 in Online Resource 2, based on the following characteristics (see Dayet 2012; Hodgskiss 2010; Pradeau 2015; Salomon 2009): & Block weight: measured to the milligram & Block dimensions: measured with a caliper to the millimeter & Main block hue: observed on natural surfaces & Powder hue: observed on microsample

Fig. 3

 3 Fig. 3 Red pigment traces and paintings on the eastern wall of Leopard Cave

Fig. 6

 6 Fig. 6 Distribution and selection of red residues found on the crushing and grinding tools: natural light photos on the left and yrd Dstretch® (Harman 2008) treatments on the right Ochre Residues on Stone Tools

Fig. 7

 7 Fig. 7 Selection of beads from Leopard Cave displaying ochre residues. Scales, 1 cm

Fig. 8

 8 Fig. 8 Stratigraphic distribution of the materials mentioned in the text at Leopard Cave. a Numerical distribution of various selected archaeological materials. b Frequency distribution of various selected archaeological materials. c, d Numerical and frequency distribution of ochres. e, f Mass distribution and mass percentage of ochres

Table 1

 1 List of the rock art sites in the Erongo Mountains cited in the text

	Site	Ochre description	Dating of the archaeological layers	References
			containing traces of pigments
			processing
	Rain Cloud	Hematite and red traces on grinding	2,500-2,000 cal BP	Unpublished data
		stones
	Fackelträger	Hematite, red traces on grinding	3,000-2,500 cal BP	Wendt 1972; Richter
		stones, pestles and beads		1991
	Leopard Cave	Hematite, ferruginous rocks, red	3,000-2,000 cal BP	Pleurdeau et al. 2012
		traces on grinding stones, pestles
		and beads
	Etemba 2	Lumps of pigment	Around 1,850 ± 50 cal BP	Wendt 1972;Richter 1991
	Etemba 14	Lumps of pigment	Around 190 ± 60 cal BP	Wendt 1972; Richter 1991
	Giraffe Shelter	Hematite and red traces on grinding	No data available	Unpublished data
		stones
	Philipps Cave	Hematite and red « ochre »	Around 3,368 ± 200 cl BP	Martin and Mason 1954
	Seal Shelter	Hematite, red traces on grinding	No data available	Unpublished data
		stones, pestles and beads
	Striped Giraffe	Small red, brown and yellow pieces Before 2,640 ± 100 cal BP	Sandelowksy & Viereck
				1969

Table 2

 2 Radiocarbon dates at Leopard Cave

	Lab ID	Laboratory	Stratigraphic Square Layer	Depth	Nature Conventional	Age cal BP (2
			complex			(cm)		radiocarbon age, BP sigma)
	SacA3262	LMC14	I	N6	c	143.5	Charcoal 2,150 ± 30	2,100 ±
	Beta-270163	Beta analytic I	N7	e	157.5	Tooth	2,190 ± 40	2,100 ±
	SacA34261	LMC14	I	M6	i	159	Charcoal 2,565 ± 30	2,600 ±
	Beta-270,164	Beta analytic I	N7	f	163	Tooth	2,270 ± 40	2,200 ±
	Beta-236,963	Beta analytic I	N7	f	166-176 Charcoal 2,430 ± 50	2,500 ±
	CA_DAT_AD63C CARAA	I4	P8	In concretion	168	Charcoal 2,105 ± 45	2,100 ±
					over the wall
	UBA-30945	14OCHRONO I	P7	f	175.5	Charcoal 2,209 ± 33	2,200 ±
	UBA-30946	14OCHRONO I	P7	g	192	Charcoal 3,064 ± 32	3,200 ±
	Beta-236,964	Beta analytic I	N7	g	196-206 Charcoal 3,250 ± 40	3,500 ±
	CA_DAT_AD63A CARAA	I	P8	In concretion	203	Charcoal 2,267 ± 45	2,200 ±
					over the wall
	SacA51308	LMC14	I	O8	Displaced (f)	224	Charcoal 2,105 ± 30	2,000 ±
	SacA42295	LMC14	I	N7	g	263.5	Charcoal 3,465 ± 30	3,700 ±
	CA_DAT_AD63B CARAA	II	P8	g	240-250 Charcoal 4,508 ± 45	5,100 ±
	SacA42299	LMC14	II	N7	g	271.5	Charcoal 3,000 ± 30	3,100 ±
	SacA51309	LMC14	II	N7	Displaced (f)	281	Charcoal 2,330 ± 30	2,300 ±
	SacA51311	LMC14	II	O8	Displaced (f)	285	Charcoal 2,345 ± 30	2,300 ±
	SacA53511	LMC14	II	O7	h	290	Charcoal 49,45 ± 30	5,700 ±
	SacA51310	LMC14	III	O7	m	300	Charcoal 13,040 ± 70	13,600 ±

Table 3 and

 3 Fig.

Table 3

 3 Stratigraphic distribution of the archaeological material of Leopard Cave within the 3 complexes of the stratigraphic sequence. * Complex III remains largely unexcavated

	Statigraphic complex	Layers	Total	Iron oxide	With potential anthropogenic	modifications	Total	Ferruginous	rock With potential anthropogenic	modifications	Total	Grinding	tools With red	residues	Total	OES beads	With red	residues	sherds Ceramic	Basalt	Lithic industries Quartz	remains Faunal
	I	a-e		0	0			0	0	1		1	31		9	7	148	116	104
	I	f	18	9		45	39	7		2	76		8	1	360	137	100
	I	g	154	97	148	123	17		11	175		43	0	448	137	94
	II	k-l		0	0			1	1	1		1		0		0	0		9	9	4
		Total	172	106	194	163	26		15	283		61	8	965	399	302

Acknowledgments The authors are very grateful to Ms. and Mr. Rust and their family for their kind permission to access and excavate the archaeological site of Leopard Cave, located on their farm. This research was supported by grants from the French Ministry of Foreign Affairs through the project "MANAM: Mis-sion Archéologique en NAMibie," the LaBex BCDiv (Biological and Cultural Diversity) for the project "Dynamique des peuples en Namibie à l'Holocène -NAMIBIE (Windhoek, Erongo)" both directed by D.P., the Observatoire des Patrimoines de Sorbonnes universités (OPUS) through the project "APaNam: Art rupestre et Patrimoine en Namibie" directed by M.L. Research by G.M. was funded by the Chaire Polyre of Sorbonne Universités. Permission to conduct research was granted by the National Heritage Council of Namibia (permit 11/2015 and permit renewal 04/2017 given to D.P.). We are grateful for the support of this institution, the National Museum of Namibia, and the French Embassy in Na-mibia. Finally, the authors wish to express their sincere gratitude to Professor Lyn Wadley (ESI, University of the Witwatersrand) for revising the English and the anonymous reviewers for their com-ments and suggestions.

Compliance with Ethical Standards

Conflict of Interest The authors declare that they have no conflict of interest.