Grotta
della Serratura (or Grotta della Chiave) was formed by karstic
processes favoured by the presence of an important fault running
in a NE-SW direction. In the Upper Pleistocene and Holocene deposits
profound changes have been noted as a result of the eustatic changes
in sea-level: high up and a long way
from the sea during the regressive phases, in the warmer periods
the cave was invaded by water and the current flat area became
a deep internal bay. Lithodomous burrows and grooves caused by
water erosion inside the cave indicate a sea-level at + 10 metres
which is referred to the Tyrrhenian transgression. Subsequent
tectonic movements have tilted these lines by about 20 degrees
towards the east.
Lithic industry from
levels 8C-D
The original stratigraphic series has been preserved nearly complete
only at the back of the cave, while at the entrance only cemented
lenses of sediments remain which have been eroded by the sea during
the transgressions, and these will be excavated in the future.
Lenses of eroded deposit are also occasionally visible on the
walls.
Stratigraphy of the back of the cave and cultural succession:
- level 1: Neolithic, end of the Diana culture. The deposition
took place following a phase of erosion of the underlying level.
- levels 2-3: Neolithic, painted pottery; dates comprised
between 6,300±130 and 6,770±170 BP. A cycle of painted pottery
is represented which relates to five successive living-floors,
separated by small depositions of clayey-silts which are archaeologically
sterile.
At the bottom there is an association of red banded pottery with
trichrome pottery, which is followed by the production of trichrome
pottery and the disappearance of red banded pottery, and finally
trichrome pottery associated with an element of Serra d'Alto style.
- levels 4-5: Final Epigravettian of undifferentiated Epipalacolithic
facies; dates comprised between 9,720±60 and 10,000±200 BP; this
facies has been interpreted as an exhausted aspect of the Final
Epigravettian in the Holocene period, with regressive characteristics.
- levels 6-7: Mesolithic, Sauveterrian phase; dates comprised
between 9,620±60 and 10,230±130 BP; the phyletic characteristics
with the underlying Final Epigravettian have enabled us to hypothesize
a local origin for the Mesolithic.
- levels 8A-8B: Final Epigravettian, transitional phase
with the Sauveterrian; dates comprised between 10,000±130 and
10,270±140 BP; derived from the previous horizon, it shows a dynamic
evolution towards the Sauveterrian. Three "Azilian style" pebbles
have been found.
- levels 8C-8D: Final Epigravettian; 11,290±90 BP (level
8C). The industry, which can be compared with the lower-Tyrrhenian
complexes comprised between the Allerod and Dryas III, appears
to be in direct evolution with the overlying one.
- levels 8E-G, 9: Final Epigravettian; dates comprised
between 11,460±80 and 13,100±120 BP.
Currently only the upper portion of the series (levels 1 -8D)
has been studied thoroughly, including the naturalistic elements.
The economic regime of the Epipalaeolithic and Sauveterrian facies
was characterised by an intense exploitation of marine resources
(fish and molluscs), which is homogeneous in the two cultural
horizons. The structural and stylistic diversity of the industries
is therefore interpreted as being indicative of original industrial
systems and not as the consequence of economic or environmental
conditioning.
