Lithic Raw Material Characterisation at Olduvai Gorge, Tanzania

Olduvai Gorge is located within the Ngorongoro Conservation Area, a UNESCO World Heritage Site in northern Tanzania along the western margin of the East African Rift System. Olduvai’s sedimentary record exhibits a complex sequence of inter-stratified lithic technologies including Oldowan, Acheulean, Middle Stone Age, and Later Stone Age assemblages. While diachronic technological change is perceptible, one aspect that remained largely unchanged through time was the totality of locally available rock types. This study constitutes Olduvai Gorge’s first systematic survey and characterisation of source lithologies using thin section petrography. The primary objectives of this thesis were to establish the range of available lithic raw materials, petrographically characterise these, and determine if there were unique inter-outcrop petrographic signatures to determine if it is feasible to source lithic artifacts at the mineralogical level. Geological samples were collected in primary and secondary positions within the greater Olduvai Gorge region. A total of seventy-four thin sections of sixty-two geological samples from nineteen sources were analysed. By way of comparative analyses, it is shown that four quartzitic outcrops have unique mineral compositions, four meta-granite varieties are unique to individual outcrops, Engelosin phonolite samples are texturally and mineralogically unique, and magmatic samples recovered in secondary position may be sourced to their volcanic centre. The results of this thesis demonstrate it is feasible to differentiate between source material by way of optical mineralogy which implies that sourcing lithic artifacts from Olduvai is possible. Altogether, these revelatory insights will allow future researchers to glean new understandings of hominin raw material transport, as well as ecological and social behaviour within the Olduvai paleobasin.