Forbidden Archeology_ The Full Unabridged Edition - Michael A. Cremo [183]
It would seem that the presence of combinations of these percussion signs would make it easy for one to identify human work on a flint object. But according to Verworn, this is not necessarily so. All the above-mentioned characteristics are symptoms of just one thing—a blow of sufficient force directed at a given point. But if nature could deliver the blow, then the presence of all the symptoms of percussion is not enough to establish human workmanship (Verworn 1905, p. 23).
The question as to whether nature can actually deliver such a blow has been much debated. Verworn (1905, p. 24) wrote: “It is generally recognized that extreme fluctuations of temperature and moisture, and the action of frost, do not result in fracturing that produces the above-mentioned features. It is otherwise with the question whether or not strongly agitated water, as in flooded mountain streams, waterfalls, or ocean shores, can throw stones together in such a way as to bring about the typical characteristics of percussion. I do not rule this out, but I would tend to believe that such things, if they occur, do so only in very isolated instances.” In this respect, Verworn is in agreement with modern authorities on lithic technology such as Leland W. Patterson (1983) and George F. Carter (1957, 1979).
Verworn (1905, p. 24), willing to consider all possibilities, further stated: “I could also imagine that falling stones, loosened by erosion, could produce such effects, but again, very rarely. Finally it would appear to me that stones pressed against each other by glacial action could produce the characteristic symptoms. In summary, the possibility that purely inorganic factors could act on flint to produce the above-mentioned signs of percussion is something I do not wish to dispute. Therefore the bulb of percussion, eraillure, striking platform, force ripples, etc., are not, contrary to de Mortillet’s view, definite criteria for intentional flaking.” Here Verworn was perhaps showing too much caution. Even in terms of his own analysis of evidence indicating percussion, it is not very likely that nature would, except in extremely rare circumstances, produce such combinations of effects.
Figure 4.15. Diagnostic features of a struck flake (Verworn 1905, p. 22): (1) striking platform; (2) bulb of percussion; (3) eraillure; (4) point of impact, with concentric circular cracks; (5) curved force ripples; (6) cracks emanating from the point of impact; (7) S-shaped curve of the plane of fracture; (8) crush mark from a previous blow that failed to detach the flake from the flint core.
Verworn believed that retouched edges on flint flakes were good, but again not absolutely certain, evidence of human manufacture. He recommended very careful study of the features of such retouching, including the depth and size of individual marks, the similarity of their planes of impact, and their arrangement in regular rows along the edges of the presume flint implement (Verworn 1905, pp. 24–25).
Unidirectional flaking on one side of an edge is generally taken as a very sure sign of human work, but Verworn (1905, pp. 27–28) stated he could “imagine circumstances in which you might have a sharp piece of flint sticking out from a wall of limestone, and then have pieces of rock falling from above, hitting the edge many times, producing unidirectional flaking.”
Verworn recommended that special attention be given to signs of use on the edges of possible flint implements. One would expect that an implement used for scraping wood, bones, or skin, or for digging the earth, would display certain characteristic markings. Verworn conducted extensive experimental research in this area.
He concluded: “It is characteristic of use-patterns that there are only small marks on the edge, on the average no greater than 1–2 mm [.04-.08 inch]. Even when an edge is used with great pressure on the hardest materials, the use marks are no longer than 5 mm [.2 inch]” (Verworn 1905, pp. 25–26). Use marks should, of course, be confined to the edge employed