Figure 2

Representative stratigraphic column for the ITC, Okote member, Koobi Fora Formation based on the sequence at FwJj14E.

Three ⁴⁰Ar/³⁹Ar dated tuffs bracket the sequence. Well-stratified, interbedded silt and fine sand units represent periods of active deposition on a delta margin and the paleosols represent temporary, emergent land surfaces, all occurring within an estimated time interval of ~20,000 years. Zones containing preserved tracks are shown with blue bars. The lower cluster of sites occurs at multiple levels along 800 m of outcrop within the indicated stratigraphic interval. Note that zones without track surfaces show significant paleosol development and sediment modification. Random test square and targeted excavation levels are noted on the right (red sites contain hominin prints; blue sites do not).