The Olduvai Gorge deposits contain a rich archaeological record documenting the evolution of hominin behavior over the last 2 million years. While archaeological assemblages in the lower sedimentary layers (Beds I-II) are well preserved in relatively secure chronostratigraphic contexts, the age of overlying beds is poorly constrained due to discontinuous exposures and lack of marker horizons, abundant erosional contacts and lack of unweathered, dateable material. As a result, Beds III-IV and the Masek Beds, have yet received little attention compared to the underlying beds. Recently, the Olduvai Gorge Coring Project (OGCP) acquired high resolution, stratigraphically continuous sedimentary cores of Palaeolake Olduvai through scientific drilling, in order to improve the geological and palaeoenvironmental contexts of the hominin record. While other studies reported in this volume have used palaeoenvironmental datasets from the cores to refine the Beds I-II records, this study combines outcrop and core stratigraphic methods to improve the chronology of Bed IV archaeological sites. Our recent excavation at HEB site demonstrates the importance of this approach to improve the stratigraphic positioning and relative age of Bed IV archaeological materials. Our results suggest that the HEB site is younger than previously thought because it was formed after depositional fill of an incised valley, which substantially removed much of lowermost Bed IV in the HEB area. The lithofacies at this site indicate lake expansion and development of Ngorongoro Highland sourced braided streams near the lakeshore at this time, which coincided with rich assemblages of artifacts, fossil fauna, and bones bearing butchery marks. This setting likely afforded a variety of resources to hominins including potable water, raw materials, refuge trees, and animal food, making HEB an important site for inferring the cultural and feeding behaviors of Homo erectus.
Bibliographical noteFunding Information:
We are grateful to the Tanzanian institutions that permitted and co-operated with OGCP's research, including the Tanzanian Commission for Science and Technology (COSTECH), the Tanzanian Department of Antiquities and Ngorongoro Conservation Area Authority (NCAA). Funding for this research was provided to NT and KS from the Kaman Foundation , the Gordon and Ann Getty Foundation , the John Templeton Foundation , the Fred Maytag Foundation, Kay and Frank Woods , and to JKN from the National Science Foundation ( BCS 1623873 ). JKN also thanks the Stone Age Institute , the Palaeontological Scientific Trust (PAST) , and Indiana University , Bloomington for funding support. We are grateful to one of the anonymous reviewers for positive criticisms and valuable comments that helped much to improve this paper. We are also grateful to Mr. Joshua Mwankunda and the entire OGCP field crew, Jesuit Temba, Jodi Pope and Jackson Kimambo. Anders Noren, Kristina Brady, and the University of Minnesota LacCore facility http://lrc.geo.umn.edu/laccore/ were instrumental in the logging and sampling of the cores.
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- Cut marks
- Homo erectus