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Other tool-making traditions seem to have supplanted Oldowon technologies by 0.25 mya. Below the point of impact on the core is a characteristic bulb with fine fissures on the fracture surface. The materials of the tools were for the most part quartz, quartzite, basalt, or obsidian, and later flint and chert. The main source of these rocks is river cobbles, which provide both hammer stones and striking platforms. Complaints that artifacts could not be distinguished from naturally fractured stone have helped spark careful studies of Oldowon techniques.To obtain an Oldowan tool, a roughly spherical hammerstone is struck on the edge, or striking platform, of a suitable core rock to produce a conchoidal fracture with sharp edges useful for various purposes. These techniques have now been duplicated many times by archaeologists and other knappers, making misidentification of archaeological finds less likely.There is a flourishing of Oldowan tools in eastern Africa, spreading to southern Africa, between 2.4 and 1.7 mya.At 1.7 mya., the first Acheulean tools appear even as Oldowan assemblages continue to be produced.Classification of Oldowan tools is still somewhat contentious.
This realisation required a rethinking of old cultural sequences in which the more "advanced" Acheulean was supposed to have succeeded the Oldowan.Abbevillian is a currently obsolescent name for a tool tradition that is increasingly coming to be called Oldowan.The label Abbevillian prevailed until the Leakey family discovered older (yet similar) artifacts at Olduvai Gorge (a.k.a.Use of bone tools by hominins also producing Oldowan tools is known from Swartkrans, where a bone shaft with a polished point was discovered in Member (layer) I, dated 1.8–1.5 mya. It is unifacial if the edge was created by flaking on one face of the core, or bifacial if on two.The Osteodontokeratic industry, the "bone-tooth-horn" industry hypothesized by Raymond Dart, is less certain. Discoid tools are roughly circular with a peripheral edge. There are scrapers, awls (with points for boring) and burins (with points for engraving).
An example is Isaac et al.'s tri-modal categories of "Flaked Pieces" (cores/choppers), "Detached Pieces" (flakes and fragments), "Pounded Pieces" (cobbles utilized as hammerstones, etc.) and "Unmodified Pieces" (manuports, stones transported to sites). Early Homo erectus appears to inherit Oldowan technology and refines it into the Acheulean industry beginning 1.7 million years ago.