Microstratigraphy of the Kibish hominin sites KHS and PHS, Lower Omo Valley, Ethiopia.

Detailed stratigraphic analysis of the Omo I and Omo II fossil localities confirms both the relational and sequential context reported by Butzer in 1969. The two fossils derive from approximately the same level within upper Member I of the Kibish Formation. Additional features of the local stratigraphic sequences indicate a complex history of depositional events, minor erosional surfaces, and weak soil formation throughout upper Member I.