This is a twisted handaxe made of Obsidian from the 800 k.a. old, early middle Pleistocene, Gombore II site. The handaxe shown here is heavily patinated, but the non hydrated raw material is clearly exposed by small chips at the edges. Twisted Acheulian Handaxes (usually Ovates and Cordiforms) have a very particular pattern. They often have a symmetrical and rounded butt and a twisted shape if viewed from the side, usually in the form of a backward S shape. At Gomore II, they seem to be mainly produced from Kombewa flakes.
East Africa is one of the few African areas with abundant Obsidian sources. Apart from Ethiopia, most of the other sources are located in Kenya, close to the Lake Naivasha basin and Mount Eburru. Relatively minor sources of volcanic glass are present in the northern portions of Kenya, east of Lake Turkana and in the southern end of the Suguta Valley. The southern Kenyan rift zone and northern Tanzania near Mount Kilimanjaro may also have been a significant source of obsidian.
In East Africa, Obsidian was frequently used only since the Middle Stone Age and is generally dominant in Late Stone Age lithic assemblages in the region. In this framework, the assemblages of Melka Kunture document the only known example of obsidian use during the Oldowan. During the Acheulian, the intense exploitation of obsidian has only been documented at Melka Kunture and at the Kenyan site of Kariandusi (around 700-900 k.a.).
Melka Kunture is a valley site, which extends for almost 6 km in both Awash River banks in Etiopia, with superimposed terraces whose remains are preserved to a maximum of 100 m of sediments. Melka Kunture is located 50 km south of Addis Abeba and part of the East African Rift Valley. At Melka Kunture there have been identified more than 70 archaeological levels so far. This sequence is only comparable with the archaeological record at Olduvai Gorge and span the times of the Oldowan, Acheulian and early MSA. The excavators suggest that there is good evidence for a general continuity in the development of technological and other cultural patterns during the whole sequence. This essential behavioural continuity seems also to correspond to the paleoanthropological evidence at Melka Kunture: Human remains associated to the Oldowan at Gombore I and to the “Developed Oldowan” (rather an early Acheulian) at Garba IV have been both referred to Homo erectus, while an early AHM is present at 120 k.a. at Garba III ( early MSA: http://www.aggsbach.de/2011/11/early-middle-stone-age-from-garba-iii/).
Obsidian twisted bifaces are present in all the excavation sectors of the Gombore II site at Melka Kuture. They are a unique not only within the archaeological sequence at Melka Kunture but also in a pan-African context, although some twisted bifaces, made of Quarztit are known from surface scatters in the Sahara and from obsidian at non stratified sites in Etiopia.
In Europe, twisted bifaces are known from the upper loam at Swanscombe, dated to the Hoxnian (http://www.aggsbach.de/2013/02/swanscombe-during-the-hoxnian/). Other assemblages with concentrations of twisted ovates in Britain appear to demonstrate a strong chronological correlation toward late MIS11. Twisted ovates are virtually absent from sites of a pre-Hoxnian age, such as High Lodge, Boxgrove or Warren Hill. They also do not appear to occur in significant numbers in assemblages younger than MIS 11/10, such as those recovered from Purfleet, Wolvercote and Furze Platt, but they are known from OIS 9 and 8 from Northern French Acheulian sites. Mousterian industries from OIS 5-3 in the Normandie and Bretagne show many examples of twisted bifaces: especially at Saint-Brice-sous-Rânes
Gallotti et al. recently demonstrated, that the conceptual scheme of the twisted bifaces is indeed different from that of the classical ones. Anyhow, there are many unresolved questions about the rare occurence of twisted handaxes during the old world Paleolithic:
- Are twisted bifaces the result from reduction strategies of classical bifaces?
- Are Kombewa flakes a prerequisite for producing such handaxes?
- Is the use oftwisted bifaces related to a specific function?
- If so, does a functional difference exist between a sinusoidal edge and a
” In the Acheulean layer of Gombore II, somewhat more recent than 875±10 ka, two large cranial fragments were discovered in 1973 and 1975 respectively: a partial left parietal (Melka Kunture 1) and a right portion of the frontal bone (Melka Kunture 2), which probably belonged to the same cranium. The analysis suggest that the human fossil specimen from Gombore II fills a phenetic gap between Homo ergaster and Homo heidelbergensis. This appears in agreement with the chronology of such a partial cranial vault, which therefore represents at present one of the best available candidates (if any) for the origin of Homo heidelbergensis in Africa”