Abstract 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.

中文翻译：

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核心地层限制了坦桑尼亚奥杜威峡谷 HEB 遗址的 Bed IV 考古记录

摘要 奥杜威峡谷矿床包含丰富的考古记录，记录了过去 200 万年来人类行为的演变。虽然较低沉积层（床 I-II）中的考古组合在相对安全的年代地层环境中保存完好，但由于不连续的暴露和缺乏标记层、丰富的侵蚀接触和缺乏未风化的、可测年的，上覆床的年龄限制很差材料。因此，与下面的床相比，床 III-IV 和 Masek 床还没有受到多少关注。最近，奥杜威峡谷取心项目 (OGCP) 通过科学钻探获得了奥杜威古湖的高分辨率、地层连续的沉积岩心，以改善人类记录的地质和古环境背景。虽然本卷中报道的其他研究使用来自岩心的古环境数据集来完善 Beds I-II 记录，但本研究结合了露头和岩心地层学方法来改进 Bed IV 考古遗址的年代学。我们最近在 HEB 遗址的发掘证明了这种方法对于改善 Bed IV 考古材料的地层定位和相对年龄的重要性。我们的结果表明，HEB 地点比以前认为的要年轻，因为它是在下切山谷的沉积填充之后形成的，这基本上去除了 HEB 区域最下层 IV 的大部分。该遗址的岩相表明此时湖岸附近的恩戈罗恩戈罗高地源辫状溪流的湖泊扩张和发育，恰逢丰富的人工制品、动物化石、和带有屠宰痕迹的骨头。这种环境可能为人类提供了多种资源，包括饮用水、原材料、避难所树木和动物食物，使 HEB 成为推断直立人文化和进食行为的重要场所。