Santander, February 19th-22nd 2008 - Aranzadi

The personal ornaments made from molluscs of the Middle-Late Magdalenian site at La Peña de Estebanvela (Segovia, Spain)
51
archaeological collection of La Peña de Estebanvela
and other sites that we are studying. Second, we
selected different types of lithic tools and abrasives.
Finally, for the experiment, we used different techniques
and played with different variables like gesture
or the state of the molluscs and registered all the
data as we went through the experiment.
The first technique used was abrasion (Fig. 4).
We have tested abrasion on 7 units; this technique
can only be executed from the outside of the shells.
We used different types of abrasives in our experiments:
fine grain and heavy grain sandstone. The
materials produced different types of striae.
Another variable that we used is the gesture selected
to abrade, that is, playing with the passivity and
mobility of the shells. In both cases we obtained a
surface with organized parallel striae, but in second
case the process took longer. The perforations
obtained display a circular contour generated by
the convex morphology of the surface of the
molluscs; their cross-section is linear. The striae of
the worked surface follow the direction of the executed
gestures: crossed, circular or parallel.
Figure 4. Abrasion. Different gestures used and circular perforation with
organized parallel striae.
The second technique used was indirect percussion
(Fig. 5). This technique is less traumatic than
direct percussion 3 and it allows better delimitation of
the desired perforation size and exact location.
Indirect percussion can be done from either the inside
or outside of gastropods and bivalves, although
in the case of the former, the dimensions of the natural
aperture may constrain perforation. We made
Figure 5. Indirect percussion. 1a-1b, from the inside of gastropod. 2a-2b,
from the outside of gastropod.
indirect percussion perforations from the inside of 6
units and the outside of 7. In two cases we were not
able to make the perforation and the Littorina obtusata
that we were perforating broke, once from the
inside of the aperture and once from the outside.
In all the cases we used perforators and the contours
obtained are mostly irregular although in two
cases the contours were determined by the morphology
of the drill and the resulting form was triangular.
The hammer used in all the cases was a hard
one, a quartzite of about 100 grams.
The obtained perforations vary in size from 1.2
to 1.4 mm on Conus and Cerastoderma, species
whose shell is much harder than those of other
species like the Littorina litorea in which we obtained
a perforation of 6 mm. The cross-sections are
irregular in all the cases.
Macroscopically we can observe in the attack
surface all types of fissures and rises although the
general tendency is for isolated rises and micro
rises. Nevertheless in the opposing surface we
found the contrary, a tendency to continuous rises,
accompanied by fissures.
The next technique used was direct pressure
(Fig. 6) from the inside and outside of gastropods
and bivalves. We made 16 perforations by pressure,
12 from the inside and 4 from the outside. In 4
cases, from the inside of a Littorina litorea, a
Littorina obtusata, a Patella and a Gibbula we
could not obtain our objective.
2
The chosen species were: 12 Littorina litorea, 8 Columbella rustica, 8 Nassarius reticulatus, 5 Littorina obtusata, 7 Cerastoderma edule, 2 Conus
mediterraneus, 2 Gibbula cineraria, 3 Patella caerulea, 1 Cerithium vulgatum.
3
We tried to use direct percussion but the technique was too severe and the results were always broken shells.
MUNIBE Suplemento - Gehigarria 31, 2010
S.C. Aranzadi. Z.E. Donostia/San Sebastián