Provenance of middle Stone Age obsidian artefacts from the central sector of the Main Ethiopian Rift Valley

Abstract

ABSTRACT:The Gademotta/Kulkuletti sites, located in the central part of the Main Ethiopian Rift Valley, represent the earliest Middle Stone Age (MSA) sequences in the country. Here we present the geochemical provenance of obsidian archaeological artefact recovered through excavation at the site. The artefacts and source materials were characterized by EDXRF and electron microprobe. Results show that the artefacts were procured from two sources, one local, and one presumably more distant, implying that despite the local availability of good quality raw material, not all obsidians were procured from a nearby source.

Earliest Stone-Tipped Projectiles from the Ethiopian Rift Date to >279,000 Years Ago

“…The Gademotta artifacts are made almost exclusively on obsidian. Geochemical provenancing establishes that the obsidian used for artifact manufacture at Gademotta came from the nearby (<2.5 km distant) obsidian source at Kulkuletti/Worja [19] , [20] ( Figure 1A ).…”

“…Non-artifactual obsidian samples ( n = 32) were collected from the Kulkuletti/Worja primary source [19] , [20] and cut into 5 cm cubes using a lapidary saw. Young’s Modulus ( E ) and Poisson’s Ratio ( v ) for the Kulkuletti/Worja obsidian were determined by the pulse method using the NDT James Instruments MK IV ultrasonic transducer in the National Museum of Ethiopia, Addis Ababa.…”

Geochemical Characterization of Four Quaternary Obsidian Sources and Provenance of Obsidian Artifacts from the Middle Stone Age Site of Gademotta, Main Ethiopian Rift

“…across the later Middle Pleistocene (Wendorf & Schild, ; Basell, ; Figure ). Previous provenance studies made on 13 archaeological obsidians sampled from sites at the Kulkuletti locality inferred that MSA hominins mainly exploited the nearby obsidian source called Worja, located within a few hundred meters from these sites (Vogel et al., ; Brown, Reid, & Negash, ; Negash et al., ; Figure ). However, two artifacts—namely Kulkuletti 9 and 10—yielded extrusion ages (Morgan et al., : Table ) and chemical compositions that are distinct from the Kulkuletti/Worja obsidian.…”

“…By sampling excavated assemblages that specifically represent undisturbed contexts in the Gademotta Fm., we provide a more confident interpretation of raw material procurement patterns across the length of the early MSA ( cf . Brown, Reid, & Negash, ; Negash et al., ).…”

“…However, two artifacts—namely Kulkuletti 9 and 10—yielded extrusion ages (Morgan et al., : Table ) and chemical compositions that are distinct from the Kulkuletti/Worja obsidian. Kulkuletti 9 and 10 were sampled from the ETH‐72‐1 assemblage housed in the National Museum of Ethiopia (Vogel et al., ; Brown, Reid, & Negash, ; Negash et al., ). Excavators of this assemblage note that artifacts “at Site ETH‐72‐1 are not in an undisturbed position.…”