320 
R.G. Bednarik 
marks made with wide enough points to withstand 
the pressure required to be applied always seem to 
have longitudinal striations, and they are often of 
non-symmetrical cross-section. For comparison, a 
steel sewing needle can produce a groove as 
narrow as 60 pm. 
The engraved grid lines on the Walyunga 
specimen show no detectable variation in cross- 
section or width, no striations, and no marks 
suggesting any microspalling, all of which are 
typical features of stone point engravings on low- 
metamorphism rocks (Bednarik 1995a: 95-7). Stone 
points applied to such rock are sensitive to 
variations in pressure or speed of movement, as 
well as very minor variations in surface 
topography or stone hardness. Narrow points are 
prone to fracture along the course of a line, 
producing characteristic 'jumps'. I have even 
observed variations in the distances of individual 
striations within a single groove drawn by just one 
tool application, and even when the operator did 
not notice any change in the precise tool orientation 
relative to the surface, or in the pressure applied. 
Nevertheless, the most reliable indication of a 
metal point occurs where a line changes direction, 
especially at points of sudden changes without 
lifting the tool from the surface. There are no 
changes in direction in the straight lines on the 
present specimen, but in view of the evidence in 
hand I have no hesitation attributing the intentional 
markings on side A to a metal tool, almost 
certainly a steel point. 
This is strongly supported by the two reversal- 
marks already noted above. It is clear from this 
analysis that the upper of the two principal 
horizontal lines has been partly redrawn, which is 
also evident from the distinct bifurcation near its 
l.h. end. The actual direction of most lines could be 
determined from several further observations: the 
morphology at crossings, where the second tool 
application tends to damage the comers of the off¬ 
side of the groove being crossed, and of course the 
second groove tends to be deeper at the crossing. 
Moreover, the two reversal-marks show the 
direction of the last tool applications in those cases. 
These tell-tales of tool direction agree consistently, 
and provide the marking sequence as depicted in 
Figure 3. 
Side B (Figure 4) 
An accumulation of densely packed, subparallel 
incisions larger than the one of side A occurs in the 
l.h. half of side B. Its markings are consistent with 
having been caused by a to and fro movement, 
with several sand grains caught between this and 
another flat surface and while considerable 
pressure was applied to these grains. This is 
suggested by locally quite deep gouges where 
angular grains can be seen to have been dragged. 
In the lower design, a truncated circulinear line, 
we have the opportunity to observe the effects of 
directional change in tool application on the 
morphology of the groove. The outline is not well 
rounded, showing the kind of uneven change of 
direction that is typical for engravings on stone 
surfaces (Bednarik 1995b: 608; Marshack 1996). 
Flowever, the groove width and groove profile 
remain uniform around the curvature, the latter 
being consistently between 120 pm - 150 pm. 
The upper, more rectilinear figure has two 
particularly informative features, the corners 
marked in Figure 4. In these two instances, the 
direction of tool application changed abruptly. 
There is no interruption of the line at point (1), but 
Figure 4 The markings on side B of the slate fragment. Scale 10 mm. 
