The archaeology of the Phuthiatsana-ea-Thaba Bosiu Basin, Lesotho, southern Africa: changes in Later Stone Age regional demography.
Despite earlier projects in other parts of the country (Carter 1978; Parkington et al. 1987) and the sporadic interest of a few South African-based workers (e.g. Malan 1942), western Lesotho has largely been neglected archaeologically. This paper summarizes research carried out between 1988 and 1990 to establish a local cultural-stratigraphic sequence and to investigate the settlement and subsistence patterns of its hunter-gatherer inhabitants. Initial results indicate major changes in regional land-use within the Holocene as well as between the Middle and Later Stone Ages.
The Phuthiatsana-ea-Thaba Bosiu Basin (PTB Basin) was chosen. Much of it had already been extensively explored in the search for rock paintings (Smits 1983) and many archaeological sites, some with obvious excavation potential, were already known. It lies close to the important South African site of Rose Cottage Cave across the Caledon River (Malan 1952; Beaumont 1978), the focus of a major research project in the eastern Orange Free State (Wadley 1991), opening up the possibility of comparing results and integrating observations to produce a prehistory of the Caledon Valley as a whole. Thirdly, the location of the National University of Lesotho within the study area provided a central base and greatly facilitated research.
Previous archaeological work in the PTB Basin has been extremely limited. Macfarlane (1943) noted Middle Stone Age (MSA) artefacts in a gravel bed near Masianokeng, while Ellenberger (1960: 460-62) reported their occurrence at Liphokoaneng and Thaba Bosiu, and excavated near Morija to the south of the Basin (Vinnicombe 1976: 113). Subsequently, Mokoallong shelter, a small site near the University campus, was excavated prior to its destruction during road construction. It seems to have had some 35 cm of culture-bearing stratigraphy as well as a basal layer that yielded 'a great quantity of bone and evidence of a large number of "hearths" consisting of bone and carbonised black and reddish material in close proximity' (Connelly 1981), but the excavation was carried out with minimal controls and the finds have since been lost; the brief description suggests they were Later Stone Age (LSA). Investigation of two abandoned Basotho village sites by Walton (1956) completes the record of pre-1988, non-rock art archaeology in the PTB Basin; along with his earlier investigation of another such settlement (Walton 1953), it represents the only Iron Age research thus far within Lesotho.
The exception to this dearth of activity is the ARAL rock-art recording project of Smits (1983), which intensively surveyed the eastern two-thirds of the Basin, the first rock art study in the region since the pioneering work of Wilman (1911). All paintings found by ARAL were comprehensively photographed and sketched, and some tracings were subsequently made from slides. A detailed analysis of the distribution of these sites in relation to the physical environment and each other was undertaken, but studies of the paintings' subjects using information obtained from San ethnography (cf. Lewis-Williams (1981)) remain to be carried out.
Environment and palaeoenvironment
The research area is bordered on the west by the Caledon River, the boundary between Lesotho and the Orange Free State province of South Africa, and on the east by the Front Range of the Maluti Mountains. Through its centre, the Phuthiatsana-ea-Thaba Bosiu River flows in a generally northeast-southwest direction. Vegetation, topography and altitude allow three geographical zones to be distinguished (after Guillarmod 1971): lowlands, foothills and mountains. In the lowlands, steep bluffs and cliffs form the perimeter of large plateaux with a gently rolling landscape in between, cut across by prominent dolerite dykes. The dykes are archaeologically important as sources of flakeable stone where they have metamorphosed older sedimentary rocks. Over much of the lowlands, sandstones of the Clarens Formation are the outcropping rock; most of the rock-shelters in the Basin are within them, typically below plateau summits or in river valleys. Extensive boulder fields occur on mesa slopes, and these were also a focus for prehistoric occupation. The lowlands, now densely settled and cultivated, were before the early 19th century covered by a mixed to sour Cymbopogon-Themeda grassland (Acocks 1975: 88), in which trees were much more numerous than they are now (Arbousset & Daumas 1968). On-going soil erosion and donga (gully) formation are relatively recent (Germond 1968).
The foothills, a zone of highly irregular outline, follow the contour of the mountains; they begin between 1800 and 1900 m above sea-level at the junction between the Clarens sandstone and the overlying basalts of the Lesotho Formation. Much of this area is also heavily cultivated, with higher areas principally used for grazing. Trees are more common here, and vegetation is transitional to the alpine grassland that dominates in the mountains, of which only the area west of the watershed of the Front Range of the Maluti falls within the region studied. This alpine grassland, dominated by Themeda triandra and, particularly at higher elevations and on north-facing slopes, species of Festuca, extends eastward, broken only by the valleys of major rivers, as far as the Natal border. Pipe amygdales in the basalt foothills and mountains are the source of the opalines (crypto-crystalline silicas) that were a preferred lithic raw material, either eroded out and carried downstream in rivers or as veins exposed in the lava.
The region's climate is subhumid -- warm summers and cool winters -- with considerable local and annual variation in both temperature and precipitation. At Maseru, July temperatures range from a mean maximum of 28 |degrees~ C to a mean minimum of 14.3 |degrees~ C, with corresponding January figures of 15.5 |degrees~ C and -0.1 |degree~ C. Mean annual rainfall at Maseru is 638 mm and rises rapidly on approaching the Front Range of the Maluti (Bawden & Carroll 1968). Most rain falls in summer, with frequent hail and thunderstorms. Snow is mostly a winter phenomenon, persisting for up to several weeks in the mountains, and frosts are extensive. Droughts are not uncommon, although not always as severe as that of 1991/92.
Palaeoenvironmental observations from within the research area derive from charcoal and archaeozoological studies. Early Holocene faunal assemblages suggest that environmental conditions at that time differed from the historically observed situation. Both red duiker (Cephalophus natalensis) and blue duiker (C. monticola) occur at Ha Makotoko, pointing to increased tree/bush cover between 10,000 and 8000 b.p., while the early Holocene fauna at Rose Cottage Cave includes vervet monkey (Cercopithecus aethiops), kudu (Tragelaphus strepsiceros) and sable antelope (Hippotragus cf. equinus) indicating that 'the valley of the Caledon River, or perhaps the area in general, could have been more wooded' (Plug & Engela 1992). The now-extinct blue antelope (Hippotragus leucophaeus) occurs at both these sites as well as at Tloutle and Ntloana Tsoana in the first half of the Holocene, but the possibility that it survived in the Orange Free State into historic times (Colahan 1990; Loubser et al. 1990) means that this is unlikely to have palaeoenvironmental implications.
These archaeozoological observations can be checked against the results obtained from analysing charcoals at Rose Cottage Cave (Wadley et al. 1992). The early Holocene levels in which the above-mentioned species occur are also unique in having charcoals dominated by Buddleja, suggesting slightly warmer and/or drier conditions than the middle and later Holocene assemblages in which a wider variety of species is common and the more moisture-demanding Leucosidea sericea dominant. The occurrence of trees such as Acacia karroo and Grewia monticola also suggests that conditions were warmer than at present between 5000 and 6000 b.p. The much higher frequency of ostrich eggshell in early/middle, compared to recent, Holocene PTB Basin assemblages may also indicate that conditions before 5000 b.p. were a little warmer and/or drier than in the 19th century, when ostriches appear to have been absent from the region.
The late Pleistocene levels at Rose Cottage Cave, dominated by Protea and other heathland species, are not relevant as only minimally dated late Pleistocene assemblages were recovered in the PTB Basin (Mitchell & Steinberg 1992). Analysis of charcoal assemblages from sites within the Basin is currently under way to enlarge upon the Rose Cottage Cave observations.
Resources for hunter-gatherers and a model for land-use
Assessment of the resources available within the PTB Basin to a hunting-gathering population is based partly upon archaeological sources and partly upon what is available there today. Although intensive agricultural settlement has greatly impoverished the present-day fauna, early 19th-century accounts (e.g. Arbousset & Daumas 1968) document large numbers of antelope, and the Phuthiatsana-ea-Thaba Bosiu River itself is named after the common duiker (Sylvicapra grimmia; Phuti in Sesotho). Faunal assemblages from archaeological contexts confirm the presence of other species (Plug 1993). A shift in exploration to small and medium-sized bovids and from large bovids and equids c. 9500 b.p. is the only clear sign of temporal change. As well as a wide variety of ungulates, LSA populations in the PTB Basin made use of ground game, notably rock hyrax (Procavia capensis) and porcupine (Hystrix africae-australis), while occasionally exploiting birds, fish and fresh-water molluscs (Plug 1993; Mitchell 1993a).
No plant remains except charcoals were recovered from the excavations, and there is therefore no direct evidence for plant-food exploitation. However, a wide range of plant foods is still present (Mitchell 1993b: table 18) and Arbousset & Daumas (1968: 250) refer to the gathering of geophytes, which are likely to have concentrated in the foothills zone and along dolerite dykes. With patches of indigenous forest more widespread before 1820 than today, fruit-bearing trees are likely to have been common in the lowlands and in kloofs in the foothills.
FIGURE 1 shows that foothill and lowland zones substantially interpenetrate within the PTB Basin. Consequently, it would have been possible to be based almost anywhere within the Basin and still have had easy access to both zones. This is reflected, for example, in the faunal assemblage from Tloutle (Plug 1993), which includes lowland species such as zebra (Equus burchelli), black wildebeest (Conno-chaetes gnou) and springbok (Antidorcas marsupialis), as well as those characteristic of hilly slopes (e.g. mountain reedbuck Redunca arundinum) and rocky outcrops (e.g. klip-springer Oreotragus oreotragus). Specific local factors, such as site aspect and size or the local availability of plant foods and firewood, may thus have conditioned the choice of which site to occupy and at what time of the year, rather than macroscale ecological variation. In Humphreys' (1987) terms, the PTB Basin may have been a relatively unstructured environment. The one probable exception are the mountains along the eastern edge of the PTB Basin, where both plant and animal resources are likely to have been comparatively scarce, and, well above the Clarens sandstone, natural shelter is also lacking. Survey of parts of this area finds very few sites, either at valley necks or where opaline veins outcrop at the top of the basalt (Parkington & Mitchell 1993). Such sites consist of artefact scatters with few formal tools reflecting an ephemeral occupation, either transient between the Basin and the main valleys of the Senqunyane and Senqu Rivers, and/or probably seasonal and activity-specific, one possible activity being the acquisition of opaline raw materials.
Summary of fieldwork
In this archaeological terra incognita the primary objective of the first two field seasons was to locate and excavate sites with long cultural sequences. Survey concentrated where the Clarens sandstone outcrops and shelters occur. In 1990 attention switched to the location and test-excavation of smaller shelters to provide a balance with the larger ones already excavated. Open sites, mostly discovered en passant, do not appear to be common, although finds of isolated artefacts are widespread. The further expansion of survey coverage away from the Clarens sandstone and areas bordering it is a matter for future research. Estimating overall site density is difficult; combining data from ARAL (Smits 1983) with those from the areas surveyed in 1988-90, it seems likely that 500 or so sites, including those with paintings, may exist in the Basin.
lab. no. uncalibrated layer associated determination b.p. assemblage Ha Makotoko Pta-5191 8370|+ or -~80 GWA 'later Oakhurst' Pta-5192 8950|+ or -~80 BLOS-UR 'later Oakhurst' Pta-5204 9290|+ or -~90 BLOS-LR Oakhurst Pta-5205 9970|+ or -~90 BLOS-LR Oakhurst Ntloana Tsoana Pta-5238 8780|+ or -~30 MCS 'later Oakhurst' Pta-5207 9690|+ or -~120 BLOS Oakhurst Pta-5237 9420|+ or -~110 BLOS Oakhurst Pta-5208 10,200|+ or -~100 BLOS Oakhurst Pta-5236 12,110|+ or -~120 BLOS Oakhurst Tloutle OxA-4069 715|+ or -~65 Interior post-classic Wilton OxA-4070 375|+ or -~65 Interior post-classic Wilton OxA-4068 5080|+ or -~80 BGL classic Wilton Pta-5158 6140|+ or -~100 CCL classic Wilton Pta-5162 6910|+ or -~80 CSLUP classic Wilton Pta-5171 7230|+ or -~80 CSLLR early Wilton Pta-5172 8680|+ or -~70 GS 'later Oakhurst' TABLE 1. Radiocarbon dates from the Phuthiatsana-ea-Thaba Bosiu Basin sites.
At each site the presence/absence of stone artefacts, paintings, daga plaster and stone-walling were recorded, along with basic locational data. Excavation potential was assessed by extent of visible archaeological deposit and of surface artefact scatters. In all, six shelters were excavated, three in the Phuthiatsana-ea-Thaba Bosiu Valley itself, two at the upper limit of the Clarens sandstone and one in a more open, lowland situation. The surface artefacts from two open sites and nine further shelters have also been analysed. Results of excavations at Tloutle (Mitchell 1990; 1993b), Ha Makotoko (Mitchell 1993a), Ntloana Tsoana (Mitchell & Steinberg 1992; Mitchell 1993a) and Leqhetsoana (Mitchell et al. in press) have already been TABULAR DATA OMITTED published. Dating of these sites is provided by 13 conventional radiocarbon dates, supplemented by six AMS dates on bone artefacts from Tloutle and Leqhetsoana.
Contrasts in Middle Stone Age and Later Stone Age settlement patterns
In an earlier consideration of site patterning in Lesotho, Bousman (1988) identified contrasting MSA and LSA settlement patterns in the Senqunyane Valley. The distribution of MSA and LSA sites in the PTB Basin shows similar patterning, although survey coverage was neither complete nor statistically random. While the majority of MSA sites are open, most LSA sites are rock-shelters, more than 90% if sites with paintings but no artefacts are included. Burial of MSA artefacts beneath subsequent deposit such that they are not visible to surface inspection is not considered a biasing factor here. The few shelters with MSA artefacts occur exclusively in the Phuthiatsana-ea-Thaba Bosiu Valley or along the escarpment at the top of the Clarens sandstone, whereas small numbers of LSA shelters are found in both the foothills and the lowlands. A further contrast is apparent in the open sites: MSA sites concentrate in the foothills, gorge and escarpment, LSA sites in the lowlands. Furthermore, MSA open sites often occupy prominent positions within the landscape that give excellent views over wide areas. Sites such as 2927 BC 19 and 2927 BC 39 may have been look-out stations for observing game. The absence of LSA sites in comparable situations may imply differences in hunting strategy compared with the MSA, possibly including a shift from hunting larger groups of animals (with larger numbers of people?) to more individually targeted hunting with traps and snares.
The PTB Basin data fit well those reported by Bousman (1988), and preliminary analysis of site distributions in the Upper Orange River Valley (Mitchell in prep.) suggests the same pattern. Identity of pattern does not mean identity of cause, and we should be wary both of biases in our data (e.g. MSA occupations of shelters may be evident only from excavation, and not from any surface indications), and of contrasting too strongly MSA and LSA patterns, generated over long periods and under differing environmental conditions, that may subsume much chronological and organizational variability. Although Bousman (1988: 35) has tentatively identified the patterns found in the Senqunyane Valley with the radiating/rotating dichotomy of Marks & Friedel (1977), he correctly points out that more information is needed before MSA and LSA settlement patterns in Lesotho can be accurately characterized.
Changes in Later Stone Age settlement patterns
With the exception of a terminal Pleistocene Robberg Industry assemblage from the base of the deposit at Tloutle (Mitchell 1990; 1993b), LSA archaeology in the PTB Basin appears entirely to post-date 12,000 b.p. Three phases can be identified.
At Ntloana Tsoana and Ha Makotoko highly informal assemblages dating to between 12,000 and 9500 b.p. have been assigned to the Oakhurst Complex; they differ from the better known Lockshoek industry of the Karoo and Orange Free State, notably in being dominated by opalines rather than hornfels, despite the widespread availability of both materials in western Lesotho (Mitchell 1993a). This may indicate a deliberate choice on the part of the assemblages' makers to assert a social identity distinct from groups to the west of the Caledon River, where opalines are not found (Mitchell & Vogel 1992). No open sites can be assigned to this period, and there is no occupation at Rose Cottage Cave at this time (Wadley & Vogel 1991), or at other sites in the Caledon Valley. A relatively sparse settlement seems to have favoured large shelters.
Among several changes apparent around 9500 b.p. is the appearance of large numbers of relatively high scrapers with a steep adze-like retouch along one or both lateral edges, apparently to assist hafting. These 'Woodlot scrapers' (Mitchell et al. in press), a distinctive aspect of the widespread 'duckbill scraper' phenomenon (Goodwin & Van Riet Lowe 1929), form a well-defined horizon in Lesotho and the northeastern Cape Province between 9500 and 7000 b.p. Also evident in the Ha Makotoko and Ntloana Tsoana sequences are increases in bipolar flaking and in the amount of crystal quartz, the first appearance of ilmenite (source of a black pigment extensively used in the 19th century; Arbousset & Daumas 1968) and an increased concentration on smaller bovids rather than large bovids and equids in the faunal assemblages. Similar assemblages occur elsewhere in the Caledon Valley, at the base of sequences at Liphofung in northwestern Lesotho (J. Kaplan pers. comm.) and Masitise in the southwest (Mitchell et al. in press), while Rose Cottage Cave was also reoccupied c. 9250|+ or -~70 b.p. (Wadley & Vogel 1991). No open sites of this age were found in the PTB Basin, but such a site occurs at Woodlot in southwestern Lesotho (Parkington et al. 1987) and Ellenberger (1960: 471) records finding 'duckbill' scrapers in open-air contexts near Cana, Berea District.
Assemblages belonging to the succeeding Interior Wilton Industry are represented in the PTB Basin only at Tloutle, though they also occur at Rose Cottage (Wadley 1991) and Masitise (Mitchell et al. in press). They show a marked increase in the frequency of backed microliths, particularly segments (which appear for the first time), and shifts in scraper morphology away from long, quadrilateral forms with adze-like lateral retouch towards smaller scrapers that are more diverse in plan form, position of retouch and the blank used for their manufacture. As with the earlier assemblages, archaeological occupation seems to have been mostly tied to large shelters; the settlement pattern is largely the same as that for the assemblages with Woodlot scrapers. Between c. 7200 and 6100 b.p. the high artefact and bone densities at Tloutle along with the presence of the only grindstones and hearths with stone-settings in the Tloutle sequence may indicate that this site functioned in an aggregation role by some of Wadley's (1987) criteria. The concentration of ostrich eggshell beads, Indian Ocean-derived Nassarius kraussianus shells and ochre at Ha Makotoko contrasts with their virtual or complete absence at Ntloana Tsoana between 10,000 and 8400 b.p.; the former site may also have been used in a phase of social aggregation and the latter in a phase of dispersal. Small-scale excavation has not confirmed this in the spatial patterning of artefact distributions and nor are differences in lithic assemblages apparent. Identification of specific site roles within the regional settlement system requires further excavation and will need a conceptual framework that goes beyond an aggregation/dispersal dichotomy.
FIGURE 5 shows that the dearth of radiocarbon-dated occupations in the PTB Basin between 5000 and 1000 b.p. reflects the situation in the Caledon Valley as a whole -- and in eastern Lesotho (Carter et al. 1988), the northeastern Cape Province (Opperman 1987) and the Middle Orange River Valley (Sampson 1972), although in these cases reoccupation is evident earlier than in the Caledon Valley. While no simple explanation of this phenomenon is likely, its widespread nature implicates environmental factors; Deacon (1974) has argued that more arid conditions, between 6000 and 4500 b.p., may have increased the risk to hunter-gatherers of using the interior of the subcontinent. Massive bodies of a fine, tan-coloured silt deposited sometime after 8370|+ or -~80 b.p. cap the levels containing Woodlot scrapers at Ha Makotoko and Ntloana Tsoana; the same sediment occurs at other sites (e.g. Ha Nqosa and possibly Tloutle) in the research area. Apparently aeolian in origin, it may have been laid down during the warmer, more arid conditions of the mid Holocene. Nevertheless, the lack of dated sites for several millennia after 4500 b.p. remains puzzling; field survey needs to investigate the possibility that occupation shifted entirely away from rock shelters and into the open at this time.
The PTB Basin was reoccupied, c. 700 b.p., in a very different settlement pattern that has left the most obvious archaeological imprint on the present landscape. Recent LSA occupation can be found in several large shelters, but is associated with little build-up of deposit and is often more strongly indicated by surface artefact scatters and paintings on shelter walls. Occupation is also evident as artefact scatters within and on the talus slopes of many small overhangs and in front of large boulders which were presumably the focus for brush shelters. Arbousset & Daumas (1968: 250) describe early 19th-century San settlements as 'some huts of branches, and three or four cabins of another kind constructed among the rocks, with which they might readily be confounded at a distance'. Associated artefact assemblages are scraper-dominated, but also rich in adzes; backed microliths are relatively few TABULAR DATA OMITTED in number, and various kinds of backed bladelet and backed point are often more common than segments. At Tloutle and Leqhetsoana bone points are found; it is likely they partially replaced backed microliths as arrow armatures (Humphreys 1979). Fragments of bifacially pressure-flaked arrowheads occur at two sites and several pressure-flaked backed microliths at Leqhetsoana (Mitchell 1991).
While most recent Holocene LSA assemblages in the PTB Basin share this 'standard' post-classic Wilton pattern, two assemblages stand out by having a relatively low scraper: adze ratio (Mokhokhong and 2927 BD 27), and one (2927 BD 16) is both poor in formal tools and hornfels-dominated. Variation in assemblage composition over small distances is also a feature of southern Lesotho and differs markedly from the higher-level geographical variation in formal tool frequencies that has elsewhere in southern Africa been related to the carrying out of different activities in different ecological zones (e.g. Carter 1978; Cable 1984). In the PTB Basin our small number of observations hints at formal tools being more common in the west than in the east. Why is there so little spatial patterning in assemblage composition? Firstly, the scale of the analysis may be too small, and ecological variation within the PTB Basin relatively minor: assemblage variability will only become apparent along a longer transect running from the Orange Free State up into the Maluti. Secondly, land utilization, more uniform in the PTB Basin than in eastern Lesotho/southern Natal, may not have involved major seasonal movements. If site use was conditioned by more specific local factors and underwent changes of function over time, artefact signatures may have blurred into a generalized pattern, scraper-dominated, but rich in adzes. Anomalous signatures may represent sites occupied less often. This would fit both the model of land-use proposed above, and observations from the northeastern Cape Province (Opperman 1987) that suggest long-distance seasonal movements have previously been overemphasized in Drakensberg prehistory.
A small site, rock-focused recent LSA pattern is also evident in southern Lesotho (Mitchell et al. in press) and in other parts of the subcontinent (e.g. Parkington 1987). Along with a more dispersed settlement pattern we may infer smaller group size and more frequent residential shifts; in recent centuries this pattern, linked to the intensive exploitation of plant foods, ground game and small bovids, may have been a response to the sharing of the landscape, not always on friendly terms, with food-producers (Parkington et al. 1986). Occupation of the Caledon Valley by Iron Age agropastoralists seems to have taken place from the beginning of the 17th century AD, although older sites are known in the northern Orange Free State (Maggs 1976); seasonal grazing and trade with indigenous hunter-gatherers may have preceeded formal Iron Age settlement. That both the PTB Basin and the Caledon Valley as a whole appear to witness a reoccupation by hunter-gatherers about 600-700 years ago (with the exception of a single, slightly older date from Rose Cottage Cave) may not be coincidental; did the near-by presence of Iron Age people act as a 'magnet' to draw hunter-gatherers back into the Caledon Valley in archaeologically visible numbers? Attractions may have included cereals, iron, livestock and livestock products, with hunter-gatherers offering services as herders and producers of ostrich eggshell beads, feathers, skins, honey, wild game and other resources. Archaeologically, we can document only ostrich eggshell beads at several Iron Age sites in the Orange Free State (Maggs 1976), but exchange of other products is attested in Sotho oral tradition. For example, the grandmother of the Phuti chief Moorosi is said to have bartered tobacco and hemp which she had grown for hyrax skins and ostrich feathers procured by the San (Ellenberger 1911: 27), while San use of iron for arrowheads is documented by Casalis (1930).
San hunter-gatherers continued to exist in TABULAR DATA OMITTED the PTB Basin, as in other parts of Lesotho, into the early 19th century. Arbousset & Daumas (1968) and Stow (1905: 183) noted that at least the western part of the PTB Basin 'from the Makaleng or Kornet Spruit to beyond Thaba Bosigo, including the 'Kheme (Qeme)' was occupied by a group that extended southwards as far as the Wepener/Zastron area. This group was called Baroa ba Makhoma Khotu by the Basotho as some of them possessed cattle (Makhomo) and they had 'chiefs', possibly hinting at the development of more formalized leadership roles. Loubser (in press), reviewing San/Sotho interaction in the Caledon Valley from an Orange Free State perspective, suggests that domestic livestock in rock paintings are only depicted (largely south of Rose Cottage Cave) where San maintained a mostly independent existence and could acquire and retain livestock beyond the zone of intensive agropastoralist settlement. Both he and Wadley (1992) both note that grass-tempered pottery of Smithfield type occurs in rock-shelters within this area, but not to the north.
The PTB Basin appears anomalous in this regard. Domestic livestock are painted at some sites (e.g. Malimong and 2927 AD 7 at Qeme), but there is no grass-tempered pottery at any of the more than 100 LSA sites surveyed in 1988-90. The pottery that does occur is generally quite thick, undecorated except for occasional TABULAR DATA OMITTED burnishing, and grit-tempered; it falls within the historically known Sotho ceramic tradition (Lawton 1967) like that found on Iron Age sites within the Caledon Valley. Those rock-shelters where it occurs in quantity (Tloutle, Leqhetsoana, Malimong, Mokhokhong) are precisely those lived in by Sotho-speakers during the 19th century. Explanation of these anomalies is hampered by the comparative lack of archaeological fieldwork in southwestern Lesotho; if Loubser (in press) is correct in viewing paintings of domestic livestock as more recent than the advent of a LSA ceramic tradition in the western Caledon Valley, factors such as differences in site use between the eastern and western banks of the river or the acquisition of Iron Age pottery by hunter-gatherers in Lesotho, rather than manufacture of ceramics of their own, may be at work. Differential participation in exchange relations with Smithfield-pottery producers, another possibility, may be gainsaid by pressure-flaked arrowheads occurring within the PTB Basin and on the western side of the Caledon River as elsewhere in the northeastern Karoo and southern Orange Free State (Humphreys 1991). Excavation of sites within western Lesotho where recent LSA assemblages occur in well-stratified, dateable contexts may provide some answers; as many sites are now used as livestock kraals the search has not yet been productive.
Summary and conclusion
Excavation and survey in the Phuthiatsana-ea-Thaba Bosiu Basin of western Lesotho has established a Later Stone Age cultural-stratigraphic sequence for this area and detailed changes in regional settlement pattern over time. Middle Stone Age settlement choices appear to have differed substantially from those of the Later Stone Age; one factor may have been different hunting strategies. In the several Holocene settlement phases identified, the principal contrast is between an early/middle Holecene pattern (large shelters and no open sites) and a recent Holocene pattern (ephemeral use of large shelters and widespread use of smaller sites, many of them painted). Although assemblages vary markedly over distances of no more than a few kilometres, spatial patterning relating to differential activity performance in different zones of the landscape is not seen. Recent LSA occupation of the research area appears relatively unstructured ecologically.
Small excavations and limited palaeo-environmental knowledge render explanation of these changes difficult. We need to view the PTB Basin as one part of a larger region encompassing both halves of the Caledon Valley. The strong ecological zonation evident in Lesotho and surrounding parts of South Africa should lead us to investigate variability in hunter-gatherer land-use and settlement/subsistence systems, including responses to Iron Age settlement, across ecological transects (Mitchell 1992b). The Phuthiatsana-ea-Thaba Bosiu Basin is ideally placed to be part of such studies along both a north-south axis within the Caledon Valley and one running west-east from the southern high veld to the Indian Ocean.
Acknowledgements. Permission to carry out fieldwork in Lesotho and to export finds for study abroad was given by the Protection and Preservation Commission of Lesotho. Without the assistance in the field of J. Steinberg, H. Thompson, T. Durden and D. Hall and many local workers, particularly J. Sengoara and M. Tsunyane, little would have been accomplished. The logistical support of B. and P. Hargreaves, E. Kalula and R. Meakins and the assistance of the chiefs and headmen of villages adjacent to the excavated sites were also invaluable. I am grateful to Dr I. Plug for the identification of faunal remains and Drs J. Vogel and R. Housely for radiocarbon dates. Conversation with N. Barton, B. Hargreaves, R. Inskeep, R. Meakins, J. Parkington, G. Prasad, D. Roe and L. Wadley has also been productive, although they are not responsible for the opinions presented.
Fieldwork and post-excavation analysis were supported by the British Academy, the Swan Fund, the Sir Henry Strakosch Memorial Trust, the Society of Antiquaries, the Faculty of Anthropology and Geography of the University of Oxford, the Prehistoric Society, and St Edmund Hall, Oxford. The research was carried out during tenure of a British Academy post-doctoral research fellowship at the Baden-Powell Quaternary Research Centre, University of Oxford and the paper was written while a post-doctoral research fellow at the University of Cape Town.
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