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.     

Focus: sulphur isotope variation in archaeological marine fauna from northern Europe

We undertook combined stable carbon, nitrogen and sulphur isotope analysis of marine and terrestrial faunal remains from two prehistoric coastal shell middens in Denmark. The aim of the investigation was to establish whether sulphur isotopes were useful in discriminating terrestrial and marine consumers in this region. We found that sulphur isotopes do separate marine and terrestrial fauna but, contrary to our expectations, we observed a negative correlation between δ³⁴S and δ¹³C values for marine fauna. We conclude that similar studies over a broader geographical range are needed before sulphur isotopes can be reliably used to study coastal resource exploitation.     

Identification of pastoral sites using stable nitrogen and carbon isotopes from bulk sediment samples: a case study in modern and archaeological pastoral settlements in Kenya

The identification of pastoral sites in the East African archaeological record is problematic. Recently, a method for the identification of degraded livestock enclosure sediments had been developed that takes into account the geoarchaeological indicators of micromorphology, phytolith concentrations and the mineral assemblages. This suite of indicators may not always be present in degraded livestock enclosure sediments. This study presents an additional indicator by which degraded livestock enclosure sediments may be identified, namely the isotopic composition of organic nitrogen measured on bulk sediment samples. We studied a highly controlled ethnoarchaeological sequence of abandoned Maasai livestock enclosure sediments sampled in Rombo area, southern Kenya. The results were compared to archaeological sediments from the Elmenteitan Pastoral Neolithic site of Sugenya, southwestern Kenya, radiocarbon dated to ca. 2000 BP (uncalibrated). The sediments from both sites were studied using all four types of analyses, i.e., micromorphology, mineralogy, phytolith concentrations, and stable carbon and nitrogen isotopic compositions on bulk sediment samples. The results show that in abandoned livestock enclosure sediments of known ages a significant enrichment in the heavy nitrogen isotope (¹⁵N) occurs, and that carbon isotopic compositions may be useful for differentiating cattle from caprine enclosures following their dietary preferences (i.e., grazers vs. browsers). A similar pattern of ¹⁵N enrichment is observed in sediments sampled within the site of Sugenya while sediments sampled outside the site's perimeter are generally depleted in ¹⁵N. The micromorphological, mineralogical and phytolith analyses support the conclusion that the sediments from within the site of Sugenya represent degraded livestock enclosure sediments. The carbon isotopic composition from the degraded dung deposits strongly suggests that livestock kept at Sugenya were cattle. Overall, this study presents new empirical data that can be used for the identification of livestock enclosures, and shows that the isotopic signatures and geoarchaeological indicators can preserve for at least two millennia.