Technology and Terminology of Knapped Stone - IRIT

3a 4 a 5 a
Fig. 32 — The Yubetsu method. 1 : shaped out core. 2 : removal of a crested blade and successive "ski
spalls", to prepare the pressure platform. 3, 4, 5 : bladelet debitage.
To be worthy of such a name, a pressure-flaked core should always be undisputably
fluted in places.
Pressure platforms can be cortical, plain or prepared. In the case of vitreous rocks like
obsidian, the pressure platform is very often partially or completely rubbed down, to avoid
slipping during debitage. The action often extends to the overhang of the core, or even to part of
the debitage surface (fig. 78). Rubbing down of the pressure platform and overhang is only rarely
documented for flint cores.
The two basic forms of cores are the pyramid and the parallelepiped.
Pyramidal cores : either have a circular pressure platform and ogival shape (fig. 31:1),
end result of a core that has been shaped out like a "mitre"; or are virtually cylindrical bullet
cores with a very much smaller pressure platform by the time debitage is finished (fig. 31:2).
Parallelepipedal cores, which are described as "flat", have a single debitage surface, or
two successive ones, as recorded in the Greek Bronze Age (fig. 31:3 and 4).
On blades and bladelets of "plein debitage "
- parallel edges and arrises, which tend to be rectilinear;
- constant thickness, mesial section included;
- no obvious ripples on the lower face;
- a butt always narrower than the maximum width of the blades, which is very rapidly
reached.
The Yubetsu metho d
The name "Yubetsu" is not intended to have any connotations regarding the geographical
area in which the method appeared, but simply refers to the fact that it was first recognized as a
method of pressure debitage in Japan 78
. Indeed, it is now ackowledged that this original debitage
78 Akazawa et aL, 1980.
79