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STONE POINT VARIABILITY (Part 1) This chapter will test the following hypothesises:
In this study a total of 577 bifacial points and 312 unifacial points were examined. These points were drawn from the assemblages of seven sites, Jimede I & II, Ngarradj Warde Djobkeng, Marrakai Creek, Mary River, Scotch Creek and Yarar. The points were manufactured from four raw materials, chert, Gerowie Tuff, quartz and quartzite. Discrete Types or Continuum of Form Hiscock (1994a) states that there are generally only three typological categories of implements in widespread use by Australian archaeologists; points, backed blades and tulas. At the lowest level of resolution, conventional analyses make no allowance for the technological and morphological changes imposed by a variety of factors. Therefore, a broad implement type, such as points, may appear to represent a discrete and typologically regular set of artefacts despite there being morphological variation between the individual specimens within the typological class. Flood (1967), Schrire (1982) and Allen & Barton (1989) have acknowledged that there was a degree of variability in the stone points analysed during their studies. Generally, after having identified that variability existed, the differences are subsumed back into the broadest of classifications, that is either points or "unifacial" and "bifacial" points. Whilst there is necessary information held in the whole sample, many of the underpinning causes of variability are no longer visible. Subject the two sub-types (unifacial and bifacial points) to a closer examination, and a continuum of morphological and technological form becomes apparent, with unifacial and bifacial points a mere technological attribute of the continuum. Bifacial and Unifacial - Size Beyond the technological divide of the two sub-types (see discussion earlier in thesis) there are dimensional differences between unifacial and bifacial points. As can be seen from Table 6, unifacial points are consistently longer, thicker, less elongated and more robust than bifacial points. Generally, bifacial points demonstrate lower ranges of standard deviations than unifacial points (Table 6). The bifacial points can be seen as more uniform with less variation in size than the unifacial points.
If the hypothesis of a continuum of form between unifacial and bifacial points is valid, then there should exist an overlapping of the dimensions between unifacial and bifacial points. In other words, the largest bifacial point cannot be dimensionally larger than the unifacial point it is has been derived from. To test this requirement, the range of the unifacial and bifacial points, at the 95% confidence level, were plotted in Figure 12. The upper boundary of the length, thickness, width and weight attributes of bifacial points is greater than the lower boundary of the attributes of the unifacial point. More importantly, the lower boundary of the unifacial point is greater than the lower boundary of the bifacial point. There is then an overlap in the dimensional attributes of bifacial points and unifacial points. Therefore, bifacial points can be the products of the reduction of unifacial points. In all instances, the largest bifacial point could be produced from the smallest unifacial point. Bifacial and Unifacial - Intensity of Retouch The continuum of form model for bifacial and unifacial points, should also be expressed in the technological attributes of bifacial and unifacial points. Retouch is a subtractive process that removes flakes from the stone point. Unifacial points then should demonstrate a lower intensity of retouch than bifacial points, because once the flakes have been removed (retouch) they cannot be reattached. The intensity of retouch of an implement can be measured by the nature of retouch scars on the dorsal surface. A high level of retouch will be exhibited by a predominance of invasive retouch scars, while a low level of retouch will be evidenced by the dorsal retouch scars being restricted to the margins of the implement.
The dorsal surface retouch scars (marginal or invasive) (Figure 9) were compared to the stone point type. It was found that there is a significant correlation between the level of retouch on the dorsal surface between unifacial and bifacial points (x2=401.776, p=0.00005, V=0.672) (Table 7). Predominantly, bifacial points are heavily retouched with most retouch scars being invasive in nature, while retouch scars on unifacial points tend to be more restricted to the implement’s margins. An invasively retouched unifacial point (15%) cannot be altered into a marginally retouched bifacial point (27%). It can however, be converted into an invasively retouched bifacial point (85%). In the continuum model it can be expected that there are two extremes of form, namely marginal retouched unifacial points and invasively retouched bifacial points. There should also exist an overlapping transition group of marginally retouched bifaces (27%) and invasively retouched unifacials (15%).
A further measure of the intensity of retouch is the modification of the dominant primary flake scars alignment on the dorsal surface (Figure 8). To test this the level of dorsal surface retouch was plotted against the alignment of the dorsal surface scars (Table 8).
There was a demonstrated correlation between the intensity of retouch (marginal or invasive) and the dominant dorsal surface scars (lateral or longitudinal) that is highly significant (x2=582.995, 0.0001 > p > 0.00005, V=0.810). A high level of retouch (invasive) removes the older pre-existing primary surface scars. The invasive retouch of bifacial points produces a dorsal surface dominated by newer lateral retouch flake scars, aligned perpendicular to the margins. As the alignment of the dorsal surface scars is a measure of the intensity of retouch it should also be associated with the point type. The scars attribute (longitudinal or lateral) was compared with the stone point type (bifacial or unifacial), (Table 9).
This analysis demonstrated that the correlation between the dominant dorsal surface flake scars and the point type is very significant (x2=359.944, p=0.00005, V=0.636). A large proportion of bifacial points have a laterally aligned dorsal surface scar, while a large proportion of unifacial points exhibited longitudinal dorsal surface scars. This association between the intensity of retouch and the stone point type is presented graphically in Figure 13.
As the intensity of retouch increases from marginal to invasive, there is a change in the point type with the highest intensity of retouch. Unifacial points constitute 86% of the marginal retouch attribute but only constitute 15% of the invasive retouch attribute. The reverse occurs with bifacial points, which constitute 14% of the marginal retouch and 85% of the invasive retouch. Figure 13 also demonstrates that high percentages (83%) of all points that have laterally aligned dorsal surface scars are bifacial points. It also shows that 79% of all points with a longitudinal aligned dorsal surface scars are unifacial. It is important to note that neither of these technological attributes, dorsal surface scars and retouch, are exclusive to any one, point type. Examples of both dorsal surface scars and both measures of retouch may be found on each implement type. Bifacial and Unifacial - Butt Shape & Platform Modification Another readily identifiable morphological feature, is the shape of the butt of the point. In this study, the butts could be categorised as either rounded or square. Similar morphological features have been identified by other archaeological studies in the region. For example, Allen & Barton (1989:55) recorded the butt shape as round, flat or concave. Schrire (1982) also recorded butt shape using the terms curved and square. The difference between the shape of the butt (rounded or square) with respect to the proportions of differing implement types (unifacial or bifacial), is significant (x2=112.554,0.0001> p >0.00005, Table 10). This indicates that a bifacial point is more likely to have a rounded butt, while square butts are found almost equally in either unifacial or bifacial points.
The butt shape of unifacial and bifacial points is highly variable. Square butts are found almost equally between bifacial and unifacial points. There is a weak association between rounded butts and bifacial points where 80% of points with rounded butts are bifacial. Another technological feature of stone points is the preparation of the platform, this can be divided into two types. That platform modification performed before the point is detached from the core (pre-detachment) and platform modification performed after detachment from the core (post-detachment). A test of the continuum model is that the removal of the platform is the final form of platform modification. Once the platform has been removed it cannot be replaced with another form of modification. Table 11 demonstrates the range of platform modifications in the sample. Cortical, conchoidal, multiple scars and faceted platform preparations are all pre-detachment processes. Unifacial points have a lower ratio (8:25) of platform removal to pre-detachment modification than does bifacial points (16:5). This is indicative of a reduction process where the pre-detachment platform modifications of the unifacial point are removed by the post-detachment modifications in deriving a bifacial point from a unifacial point.
No single form of platform modification can be identified as being restricted to any one, point type. There is however, a much greater proportion of bifacial points with the platform removed than unifacial points. Summary No single test can prove or disprove the continuum of form model for bifacial and unifacial points. Nevertheless, the combined results of the detailed examination presented above do provide evidence of the continuum model. The evidence for the existence of a unifacial to bifacial continuum is as follows:
The final evidence for a continuum of form between unifacial and bifacial points, is that none of the attributes tested was confined to a single point type. Figure 14 demonstrates that in every attribute tested there was a continuum of change from one extremity to the other with an overlap group between. There were bifacial points with features found on unifacial points and unifacial points with features found on bifacial points.
Author: Wayne
Roddom, Dept. Archaeology and Anthropology |
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