Concerning a Cupule Sequence on the Edge of the Kalahari Desert in South Africa

IntroductionCupules are manmade, roughly semi-hemispherical depressions, not normally more than -8 cm in diameter, that were produced on hard rock surfaces by hammerstone percussion (Kumar and Krishna 2014), reportedly supplemented or replaced on softer stones by varying combinations of abrasion and incision (e.g. Clark 1958; Van Peer et al. 2003). The first account of their presence in sub-Saharan Africa occurs in A. A. Anderson's (1888) description of an isolated massive rock seen in 1867 near the confluence of the Notwane and Limpopo Rivers, the many petroglyphs on which included 'a small hollow of cup shape with two circles of the same round the centre one ...'. Since then, Africa south and east of the Sahara has produced many more cupule occurrences that a literature survey shows to be widely, but unevenly, distributed over its more than 18 million km2 extent, based on cited data for the localities listed in Appendix 1.Of these sites, only three have provided minimum or bracketing chronometrie ages, beginning with Chifubwa Stream Shelter in Zambia, where excavations (Clark 1958) revealed a sequence comprising thin surface soil with a few shards, -2 m of sterile yellow-orange sand, and up to 0.7 m of basal red sand containing Later Stone Age (Nachikufan 1) lithics (Clark 1950). The shelter wall then exposed, down to just 3 cm above that occupation level, was entirely covered by incised and then abraded petroglyphs that are dominated by vertical lines, inverted Us, with or without a central vertical line, and cupules which are mainly randomly placed. Only a single composite l4C age was obtained then, but the later dating of various regional sites (Miller 1971; Sampson 1974) placed the artefact level between -25 and 13 cal ka ago (Weninger and Joris 2008), and it is consequently considered probable that the Chifubwa petroglyphs were made at some time within that interval (Clark 1958).Then, at Rhino Cave in the Tsodilo Hills of Botswana, fieldwork in 1995 and 2006 (Robbins et al. 1996; Coulson et al. 2011) probed an over 2 m deep deposit with Later Stone Age overlying Middle Stone Age in the -94-66 ka range (Robbins et al. 2000; Phillipson 2007), that is flanked by a cave wall covered by over 300 fairly fresh to heavily weathered ground grooves and cupules (Coulson et al. 2011). A rock fragment with an artificial groove on its one face was found in the Middle Stone Age level (Coulson et al. 2011), and the organic coatings on two cupules have been dated to -5 ka ago (Brook et al. 2011), with those findings here taken to indicate that the cupule ages are minimum estimates only, and that the marked mobiliary item was either discarded there, or had spalled off from the adjacent panel, in which case it predates -66 ka bp. And lastly, albeit beyond present savannah bounds, is Sai Island on the Nile in northern Sudan (Van Peer et al. 2003), where a -2.5 m deep sequence on bedrock contains Earlier Stone Age (Acheulian), followed upwards by Early Middle Stone Age (Sangoan) and Middle Stone Age. In the Sangoan strata, with bracketing OSL ages of 220-180 ka ago, were found three sandstone slabs, each with a single incised cupule, of which one is over 100 mm wide (op. cit. Fig. 3).From this chronometrie evidence it is apparent that African cupules were made over a timespan ranging back to before -220 ka bp, and that they occur, on present evidence, in all Stone Age periods subsequent to the Earlier Stone Age. Furthermore, the absence of firm consistent evidence for extraneous organic residues in them, or that they were formed fortuitously (Walker 2008), does not support a utilitarian purpose for cupules, which are, rather, best taken to be a primal form of palaeoart (Bednarik 2007, 2008). However, cupules may also occur at the very point where the striking of rock gongs (Fagg 1956, 1957) results in a ringing tone, with the sometimes very weathered state of those surfaces suggesting that drumming (and music generally) may have very ancient beginnings (Goodwin 1957). …