West of Lake Baringo, the Kapthurin Formation preserves a newly discovered archaeological complex with technical elements otherwise described as unknown in eastern Africa. The assemblages are classified within the East African Acheulian, yet they display large-scale applications of the Levallois method. This technique was already known in the Acheulian of southern Africa, creating a technological connection across regions.

The Kapthurin material also includes refined blades. Their presence broadens the range of technological practices associated with East African Acheulian assemblages and challenges any simple equation between Acheulian technology and a narrow set of large bifacial forms. The evidence is especially relevant to the source’s broader argument that Middle Pleistocene assemblages often show permutations of a limited group of technological and typological components.

Margaret and R. E. F. Leakey explored and studied the complex. A mandible found in the same beds was reported to show features reminiscent of Homo erectus, although the wording preserves an interpretive qualification rather than a definitive taxonomic identification. The association of this fossil evidence with the distinctive lithic assemblages makes Kapthurin an important candidate for further chronological and behavioral study.