Obsidian types from Holocene sites around Lake Turkana, and other localities in northern Kenya

Obsidian has been widely used by early Holocene hunter-gatherers and succeeding Pastoral Neolithic peoples in northern Kenya. Here we report the results of over 2000 electron microprobe analyses of artifactual and non-artifactual obsidian from the greater Lake Turkana region. Of the 15 compositional types of obsidian observed, a preponderant type is widespread across the region from the Barrier in the south to Ileret in the north and east as far as Kargi. This obsidian is the principal type at Lowasera and most Pastoral Neolithic sites, including the Jarigole Pillar site and Dongodien (GaJi4). The source of this obsidian is not known, but based on its distribution the source may be located on the Barrier or in the Suguta Valley immediately to the south of Lake Turkana. Although there are several possible sources of local obsidian identified for minor types, in stark contrast to the central part of the Kenyan Rift, major sources of obsidian available for artifact manufacture are not known in the Lake Turkana region. The lack of obsidian from demonstrable Ethiopian Rift and central Kenyan Rift sources, and the absence of obsidian with compositions found at the Turkana area sites in assemblages in the central part of the Kenyan Rift suggests that the earlier Pastoral Neolithic peoples around Lake Turkana interacted with each other, but perhaps not as strongly with people farther south along the Rift Valley, even as herding practices were expanding to the southward into central Kenya. (C) 2011 Elsevier Ltd. All rights reserved.