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secondary flake scars on possible implements. He said that he would measure 100 angles, from about 30 tools. Thus he would measure an average of 3.33 angles per object. As far as eoliths are concerned, they are mostly natural flint flakes or blocks that have been subjected to some limited intentional retouching. So they should have both intentional and natural flake scars. If Barnes randomly picked 3 flake scars per eolith for his measurements, it is quite possible that this would introduce enough obtuse angles to violate his requirement that no more than 25 percent of the measured angles should exceed 90 degrees.

Patterson and his coauthors (1987, p. 92) then stated: “Another source of error in the analysis of striking platform geometry is the confusion of secondary planes with true residual striking platforms on flakes.” Patterson (1983, p. 301) had earlier pointed out: “In collections both of man-made and naturally fractured stone . . . Barnes identified many specimens with flake-scar angles greater than 90 degrees. These observations must result either from incorrect identification of striking platform geometry or from incorrect angle measurements, if man-made controlled flaking or simulated controlled flaking by nature is being identified. Core flake-scar edge angles, and corresponding ‘beta’ angles on product flakes, cannot be obtuse in controlled flaking. On a flake, the striking platform and ‘beta’ angles are most often incorrectly identified when a secondary fracture has removed the true residual surface of the striking platform and has left another flake scar surface which gives the incorrect impression that these angles are obtuse. It must be emphasized that intact examples of controlled flaking will have striking platform and ‘beta’ angles under 90 degrees. . . . Studies such as that published by R. E. Taylor and L. A. Payen that use

‘beta’ angles on flakes as the basis for concluding that the sites of Calico and Texas Street do not have man-made specimens are questionable for the reasons given here.”

Further emphasizing this fundamental flaw in the Barnes method, Patterson (1983, pp. 301–302) stated: “Previous investigators have obtained the impression that collections of naturally produced lithic flakes have many striking platforms with obtuse angles, but this appears mainly to be a case of incorrect identification of striking platform geometry. . . . Collections of naturally fractured rock often superficially appear to have a high percentage of flakes with striking platforms that have obtuse angles simply because so many residual striking platforms are missing and secondary fracture planes are incorrectly identified as remnant striking platforms.”

Thus even collections of naturally broken stone should satisfy the Barnes criterion, if the original striking platform angles can be properly identified. It would thus appear that the method devised by Barnes is not appropriate for distinguishing between the effects of natural forces and intentional human work on pieces of stone.

“Probably the greatest problem with the Barnes method,” observed Patterson, “is that it considers only a single attribute, and it is very difficult to conclusively demonstrate the presence or absence of human workmanship in that manner” (L. Patterson et al. 1987, p. 92). In another paper, Patterson gave some guidelines for a more suitable method of determining whether or not flaked stone objects are of human manufacture: “Demonstrate the likelihood of human manufacture by combinations of key attributes. Studies of single attributes will always remain unconvincing” (L. Patterson 1983, pp. 298–299).

Among the key attributes that Patterson suggested were the presence of clearly marked striking platforms (especially those modified for better flaking), multiple examples of tool types, platform angle measurements, the presence of bulbs of percussion and associated ripple lines, and the geological context. Other attributes that might be considered are the presence of regular retouching, sharp edges (nature tends to produce rounded edges),