The third field season of the Late Quaternary Human Evolution in West Turkana Project built on earlier findings to continue investigating the biological and cultural evidence for the evolution of our species, Homo sapiens, in the Turkana Basin. The work focused on the characterisation of the geology and geomorphology of Kalakoel and Nakwapo, the mapping of shell exposures at Natome, and the survey of the potential living site of KL4. The season was disrupted by storms and floods that destroyed geological trenches and archaeological profiles, as well as required moving the entire camp. Despite this, several important findings were made that complement those of previous years and that extend the temporal range of the sites being surveyed.
The work of the 2011 field season focused on the geology of Nakwapo, the relationship between the eroded ‘badlands’ and the flat plains to the South, as well as on the mapping of hills and shells throughout Natome. The specific objectives of the 2011 field season were to:
- carry out a number of small excavations to establish the stratigraphic association between the present-day surface in the area and the eroded sediments where the surface fossils are found;
- to excavate a number of small and large trenches for geo-morphological study in collaboration with Prof. Hema Achyuthan, from Anna University, Channai, India;
- to survey the area for volcanic strata in collaboration with Prof Clive Oppenheimer, from the University of Cambridge;
- to survey the area to the south of the main Pleistocene/Holocene palaeolake shoreline, in particular around the locality Kalakoel 4 (KL4) where a fragmentary exposed human skeleton was found in 2009;
- to continue the general survey of all main localities under study, focusing on identifying the extent of Middle Stone Age archaeological scatters and their geological context.
Small excavations at Kalakoel 1 (KL1) and Kalakoel 2 (KL2)
A small excavation was carried out at the locality Kalakoel 1 (KL1), where extensive erosion has exposed many fossils of a lake margin nature. A part of this locality was surveyed in some detail in 2010. The excavation was set at the top of a hill, where least erosion had taken place, to try to establish the sequence between the exposed/eroded strata and the current topography. The excavation revealed recent sandy layers at the top, and the lake sediments below, with discontinuous shell layers in between. A small number of mainly aquatic fossils were found in the trench, as well as an almost complete giraffe vertebra. Samples for radiocarbon and OSL dating were collected. Similarly, a small excavation was carried out at the locality Kalakoel 2 (KL2), cutting through an eroded exposure. This revealed a concentration of almost all fossils (mainly aquatic) within a single organic rich layer, the rest being sterile lake clays.
Geological trenches – Nakwapo and Natome
Two large trenches were excavated for geo-morphological study and collection of dating and geological samples. The largest of these was at the locality Nakwapo, were Aeolian erosion has exposed the northeastern face of set of hills, creating an approximately 10 metre column of lake sediments. A comparatively smaller trench was excavated at Natome, bridging the sediments above and below the main shell layer observed at various points throughout the site. The geological trenches were logged by Prof Achyuthan and Prof Foley, and samples for environmental analysis and OSL dating collected throughout.
Survey for volcanic materials
A brief survey for volcanic rocks was carried out during Prof. Oppenheimer’s visit. Virtually material of a volcanic nature had been identified in previous seasons, so although brief, the survey was important to confirm earlier observations. The work included an area survey of volcanic strata and materials, also focusing on the exposed sediments within the geological trenches. No tuffs were identified either in the naturally exposed sediments or in the trenches excavated before the storms, and almost no volcanic materials at all, only the occasional small pumice rock.
Survey of the area to the south of the shore of lake PalaeoTurkana
In order to complement the information gathered along the late Pleistocene/early Holocene lake shore, the area to the south of the eroded hills of Natome and Kalakoel was surveyed. This focused around the site of KL4, where a brief visit in 2009 identified a very fragmentary human skeleton exposed on the surface. The locality of KL4 sits on a ridge that runs for approximately 2 km east-west and c. 2 m above an extensive flat plain to the north. Survey of the area to the east from where the fragmentary skeleton was recorded in 2009 revealed an extensive archaeological site, characterised by large numbers of surface-exposed fragments of hippopotami, stone tools (mainly microliths) and some pottery sherds. The site also contains a number of burials, most of which have been exposed by erosion and are on the surface being further fragmented by trampling by the numerous herds of goats. Three of the partially exposed skeletons were excavated, although these were in a poor state of preservation, and a number of the human bone surface scatters collected.
General palaeontological survey of all localities
In parallel to the other activities, the general survey of the various palaeontological localities in the area continued the recording and collection of fossil specimens exposed on the lake edge surface. The survey concentrated on Natome, attempting to map the extent of the main shell layer across the different hills. Collection of fossils was restricted to only those specimens of anatomical or taxonomic interest. Overall, the fauna from Natome and KL1 are very interesting in that it accurately reflects the small to large animal community at the edge of the late Pleistocene/early Holocene high-lake shore. Unfortunately, the remains are mostly extremely fragmentary, which limits the scope of anatomical studies.
A new locality, named Kalakoel 7, was identified to the North of KL2, where fossilised fragments of a human cranium were found. The ‘Oyster Site’ (KL3), where an extensive Middle Stone Age site and fragmentary human calotte were discovered in 2009, was re-visited. Five small fragments of hippopotamus (?) fossils found on the surface together with the lithics were collected to send for U-series dating in Australia.
The 2011 fieldwork season accomplished its main objectives of exposing long stratigraphic sections from which samples for dating and other analyses could be obtained. The data obtained from these analyses will hopefully throw more light on the complex geo-morphological setting of the area, in which the repeated expansion and recession of the lake throughout the Quaternary has created in places a palimpsest of sediments. The recording of the spatial distribution of surface fossils continued, together with the collection of specimens that build the overall comparative sample of the fauna of this age in West Turkana. The identification of the burials at KL4, and their partial excavation, opened up a new avenue of study to further understand the population of hunter-fishers who lived and foraged by the shore of the PalaeoTurkana lake. Finally, the first formal survey of the MSA locality of KL3 disclosed an extensive, and potentially well contextualised, late Middle Pleistocene site.
FIELD TEAM 2011
The 2011 scientific field team:
- Dr Marta Mirazon Lahr, LCHES, Univ of Cambridge (UK/Argentina; palaeoanthropologist)
- Prof Robert A Foley, LCHES, Univ of Cambridge (UK; palaeoanthropologist)
- Prof Hema Achyuthan, Geology, Anna Univ, Chennai (India, geologist)
- Prof Clive Oppenheimer, Geography, Univ of Cambridge (UK; volcanologist)
- Dr Aurelien Mounier, LCHES, Univ of Cambridge (France; palaeoanthropologist)
- Dr Federica Crivellaro, LCHES, Univ of Cambridge (Italy; anthropologist)
- Alex Wilshaw, LCHES, Univ of Cambridge (UK; PhD student in Palaeoanthropology)
- Denis Misiko Mukhongo, Univ of Cambridge (UK; PhD student in Genetics)
- Frances Rivera, LCHES, Univ of Cambridge (US; PhD student in Palaeoanthropology)
- Ben Copsey, LCHES, Univ of Cambridge (UK; PhD student in Palaeolithic Archaeology)
- Julie Lawrence, LCHES, Univ of Cambridge (UK; PhD student in Palaeoanthropology)
- Carolin Vegvari, LCHES, Univ of Cambridge (Austria; PhD student in Palaeoanthropology)
- Nicole Grunstra, LCHES, Univ of Cambridge (Holland; PhD student in Palaeoanthropology)
- Justus Edung, NMK Lodwar (Kenya, Turkana; Senior Field Researcher)
- Samuel Muteti, NMK Nairobi (Kenya; Senior Field Researcher)
- Robert Moru, TBI/NMK (Kenya, Turkana; Senior Field Researcher)
The 2011 field team:
- James Lokuruka, TBI (Kenya, Turkana)
- Pedro Ebeya (Kenya, Turkana)
- Michael Emusugut (Kenya, Turkana)
- Peterson Kitui Eperon (Kenya, Turkana)
- Simon Dakacho Eperon (Kenya, Turkana)
- Robert Ng’ichilia (Kenya, Turkana)
The 2011 field camp support team:
- Odongo Maura, Cook (Kenya)
- Nelson Namasa, Cook Assistant (Kenya)
- David Lomuria, Askari (Kenya, Turkana)
- Francis Lowan, Askari (Kenya, Turkana)
- Joseph Erupe, Camp Assistant (Kenya, Turkana)
- Joseph Lopua, Camp Assistant (Kenya, Turkana)
- Robert Ng’irotin, Camp Assistant (Kenya, Turkana)
- David Kitivi, Driver (Kenya)