Two-million-years of obsidian extraction, utilization, and exchange in eastern Africa (original) (raw)
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Journal of Archaeological Science: Reports, 2018
The complexities of Later Stone Age environmental and behavioral variability in East Africa remain poorly defined, and toolstone sourcing is essential to understand the scale of the social and natural landscapes encountered by earlier human populations. The Naivasha-Nakuru Basin in Kenya's Rift Valley is a region that is not only highly sensitive to climatic changes but also one of the world's most obsidian-rich landscapes. We used portable X-ray fluorescence (pXRF) analyses of obsidian artifacts and geological specimens to understand patterns of toolstone acquisition and consumption reflected in the early/middle Holocene strata (Phases 3–4 of the Eburran industry) at Gamble's Cave II. Our analyses represent the first geochemical source identifications of obsidian artifacts from the Eburran industry and indicate the persistent selection over time for high-quality obsidian from Mt. Eburru, ~20 km distant, despite changes in site occupation intensity that apparently correl...
Twenty-sixMiddle Stone Age obsidian artifacts from the Gademotta Formation were instrumentally characterized by energy dispersive X-ray fluorescence. Analysis of artifacts from the type locality enabled sampling of a greater time depth while avoiding the uncertainties in previous results on artifacts sampled from a “disturbed” context at Kulkuletti. Moreover, the analysis here of source samples from Alutu, Worja, and the previously unstudied Bora and Ficke sources in the broader region offers a better understanding of prehistoric lithic raw material procurement. The local Worja source, an aphyric obsidian excellent for tool production, substantially dominates the assemblage. Bora, another aphyric obsidian in the wider region, is also present, but not common. The vitrophyric Ficke and Alutu obsidian sources with abundant sanidine phenocrysts were not present in the archaeological assemblage, and likely did not compete withWorja and Bora for tool production. At least one artifact appears to be from an as yet unknown source, thus confirming results of previous studies. A few artifacts share similar geochemical composition with the Worja and Bora sources, thus highlighting the complexity of obsidian source studies in this part of the rift where multiple geographically close sources may share similar crustal material.
Proceedings of the 2021 International Obsidian Conference. Regents of the University of California , 2024
We characterized 42 obsidian samples from the Baantu obsidian source in southwestern Ethiopia, including 25 outcrop samples and 17 surface artifacts, using portable X-ray fluorescence (pXRF) spectroscopy. We then compared these source data to 116 obsidian artifacts from Mochena Borago Rockshelter. Results indicate that at least three geo-chemical source clusters are represented at the Baantu source: one derived from sampled outcrops and two deriving from as-yet unknown source locations. Comparing these data to obsidian artifacts at Mochena Borago excavated from levels dated to > 50 ka and ~44 ka BP, early levels dating to > 50 ka preserve obsidian from as many as six as-yet unidentified sources, while Baantu obsidians were in the minority. By ~44 ka cal BP, Mochena Borago occupants procured most, if not all, of their obsidian from the Baantu source. Compar-ison to regional published obsidian source data suggests little, if any, procurement from northern sources within the Ethiopian Rift. We need more regional survey and artifact characterizations to identify the spatial scale and directionality of stone procurement in this area, but these data provide evidence that the occupants of Mochena Borago Rock-shelter engaged with a variety of stone raw materials across periods of major ecological and likely social change in the Late Pleistocene Horn of Africa.