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Until very recently, African simple flake and small pebble tool technologies were vaguely separated into the Early Stone Age (ESA), while the larger bifacially worked cores and flakes were referred to as the Middle Stone Age (MSA); comparable technologies throughout Europe are known as Early Paleolithic (EP) and Middle Paleolithic (MP), respectively. To lessen confusion, ESA and MSA categories are sometimes interposed with the—just as vague—European system of classification. The only practical classification system is one that critically assesses true industrial complexes (e.g., Oldowan, Karari, Developed Oldowan, and Acheulean) or degree of technological innovation, such as J.D. Clark’s Mode 1–5 preparative frameworks.
The earliest flaked stone technology consisting of split cobbles and simple flakes made mostly of trachyte, rhyolite, basalt, and quartz come from the Gona sequence of Ethiopia dated at 2.6 million years ago and the Hadar sequence, both within the Kada Hadar Member of the Hadar Formation, dated at 2.3 million years ago. Although Gona has the oldest known stone tools, the Kada Hadar stone flakes were recovered on surface and in situ where the A.L. 666 maxilla (upper jaw) attributed to early Homo was discovered (Kimbel et al. 1996). In addition, stone tools dated at 2.3 million years ago have also been recovered from the Omo deposits in southern Ethiopia and at Lokalalei, West Turkana, from the Nachukui Formation.
Oldowan Industrial Complex—Early Oldowan is a lithic industry based upon artifact assemblages from Bed 1 and Bed 2 at Olduvai Gorge (Leakey 1971). Overall the Oldowan complex consists of modified (deliberate flaked) pieces of stone or battered cobbles that are classified into several types: hammerstones, choppers, scrapers, discoids, polyhedrons, spheroids, subspheroids, burins, and protobifaces. Overall assemblages are classified by artifact type and relative frequency. For instance, typical Oldowan assemblages are localized and consist of 28 to 79 percent choppers made from varied resources (e.g., quartzite and chert) and in proximity to raw sources. Less than 28 percent of choppers for all tools/cores in assemblages may be indicative of a more progressive lithic complex. Two examples that are thought to lead to the Acheulean Industry are:
(1) Developed Oldowan A—Lithic industry based upon artifact assemblages from upper Bed I, lower Bed II at Olduvai Gorge. Artifact assemblages have low frequency of choppers, and a greater abundance of spheroids, subspheroids, and small scrapers. In addition, protobifaces (a small core not extensively worked on both sides) appear in the record.
(2) Developed Oldowan B—Lithic industry based upon artifact assemblages from lower Bed II through middle Bed III at Olduvai Gorge (Leakey and Roe 1994) and from Melka Kontouré of Central Ethiopia ca. 1.7 to 0.1 million years ago. Artifact assemblages have a greater frequency of core forms (discoids and choppers), and the first appearance of a small bifaces (albeit few in number). Many have argued that this industry can be subsumed in the Acheulean industry; however, Mary Leakey maintained that the Developed Oldowan B is consistent with Oldowan tool traditions.
Acheulean Industry—Lithic industry originally based upon large bifaces found at St. Acheul (France), but in Africa this industry is based upon artifact assemblages from upper Bed II at Olduvai Gorge and at Konso (Ethiopia), Olorgesailie, and Melka Kontouré—to name a few of the more important sites. Artifact assemblages are composed of large bifaces, like handaxes, picks, and cleavers, and all show a high degree of standardization, something that was missing form earlier flake stone techno-complexes. Isaac (1977) suggests that African Acheulean is characterized by the use of very large flakes (less than 10 centimeters in length). Earlier Acheulean at Olduvai utilized smaller cores when preparing bifaces.
Levallois-type cores are prepared by an elaborate
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