This bifacially-flaked basalt cobble from Koobi Fora, Kenya, dates to the Oldowan period, ca. 1.65-189 million years ago.  Cores like these are sometimes referred to as ‘pebble choppers’.  The model was made from a resin cast of the actual tool.

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The deep percussion scars on this artefact resulted from hard-hammer percussion flaking of a water-rolled volcanic cobble.  The flaking strategy involved using the edges of prior scars as platforms for striking flakes from the opposite face, creating a bifacial edge.  The flakes are well-struck and the spacing of the scars shows an expert knowledge of the basic aspects of flake removal, reflecting cognitive abilities not clearly apparent in the Lomekwian.  The flaking created a chopper-like tool and the cortical surface opposite the cutting edge would have prevented injury to the hominin’s hand during use.  However, it is possible that the desired product was the razor-sharp flakes that were detached, and this core was a byproduct in making flake tools.  Bifacial cores like this are also common in the subsequent Acheulean period, and continued to be made by many cultures into the recent past.

Archaeology and Palaeoanthropology teaching collection, University of New England.

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Koobi Fora is located on the eastern shore of Lake Turkana, part of the Rift Valley.  The region is a focus of ongoing fieldwork sponsored by the Koobi Fora Research Project.  This artefacts was recovered during fieldwork by Glynn Isaac at the site FxJj 1, also referred to as KBS (or Kate Behrensmeyer Site).  The volcanic ash layer at that site (KBS Tuff) dates to ca. 1.65-1.89 million years ago, providing an age for the stone artefacts.  The age of the Oldowan artefacts suggest that the tools were made by Homo habilis.

Oldowan stone-flaking technology is among the oldest in the world, dating from 1.7-2.6 million years ago in the Rift Valley of southern Africa.  Oldowan assemblages were first studied and classified by the archaeologist Mary Leakey.  In 2011 stone artefacts were discovered at a site called Lomekwi 3, also located in Kenya’s Rift Valley, dating to ca. 3.3. million years ago.  These are widely recognised as an industry preceding the Oldowan, called the Lomekwian, although some archaeologists argue that the stratigraphic context of the finds is not secure (and thus they could date later than this).  The issue is an important one for evolutionary studies, as the age of the Lomekwian suggests that the tools were made by an Australopithecus, and not by a member of our own genus, Homo.