Wetland diagenesis and traces of early hominids, Olduvai Gorge, Tanzania

Daniel M. Deocampo, Robert J. Blumenschine, Gail M. Ashley

Research output: Contribution to journalArticlepeer-review

53 Scopus citations

Abstract

Lateral variations in whole-rock and clay geochemistry of basal Bed II claystones in Olduvai Gorge, Tanzania, reflect water quality differences across the Eastern Lacustrine Plain ∼1.75 myr ago. Bulk Ba/Sr and (Na2O + K2O + MgO)/Al2O3 range from 1.4 to 4.2 and from 0.7 to 1.4, respectively, and indicate leaching of lacustrine claystones beneath freshwater wetlands at times following lake retreat. Bulk MgO/Al2O3 (0.3-1.0) and molar Mg/Al (0.5-3.9) ratios of <0.2-μm clays reflect alteration of Mg-rich lacustrine clays. These indicators point to freshest conditions near Locality 43 of Hay (1976; HWK-East; Leakey, 1971), moderate conditions to the east (Locality 40-MCK), and high salinity and alkalinity to the west (Localities 85-VEK, 45-FLK). Clay geochemistry and artifact abundances are well correlated (r = -0.67, p < 0.005), suggesting a relationship between paleowater quality and hominid paleoecology. This pattern is consistent with predictions of greatest artifact discard/loss around freshwater sources where scavanging opportunities were greatest for hominids. This quantifies a relationship between artifact density distribution and a paleoecological proxy over landscape scales for the first time in Early Stone Age archaeology. In contrast, fossil bone abundance is uncorrelated (r = 0.14, p = 0.6), reflecting more complex taphonomic processes. Quantitative tests of landscape-scale land-use models are important for understanding early hominid behavior and its evolution.

Original languageEnglish (US)
Pages (from-to)271-281
Number of pages11
JournalQuaternary Research
Volume57
Issue number2
DOIs
StatePublished - Mar 2002

All Science Journal Classification (ASJC) codes

  • Arts and Humanities (miscellaneous)
  • Earth-Surface Processes
  • Earth and Planetary Sciences(all)

Keywords

  • Clay minerals
  • Diagenesis
  • Early hominids
  • Landscape paleoanthropology
  • Olduvai

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