This was the 11th campaign of excavations carried out by the University of Siena’s Laboratory of Prehistoric Archaeology and Interuniversity Research Centre for the Study and Promotion of Prehistoric Cultures, Technologies and Landscapes.
During the 2015 campaign, the investigation of the evidence for the open-air mining of cinnabar continued. This began with the removal of a baulk left in to show the stratigraphic sequence existing in the mine. Its removal was necessary as it covered a crucial point for reading the stratigraphy of the entire area. In effect, an inconsistency between the stratigraphic sequence in the north sector and that in the south sector of the excavation area was revealed. The two areas appeared to be separated by a cut in the limestone bedrock constituting the level on which the archaeological deposit in the south sector rested, and which is interpreted as a probably mining surface.

The cut, which probably ran along a natural fracture in an east-west direction, met the east wall (East Front) forming a right angle and seemed to correspond with another mine face (South Front) obliterated and filled with detritus and cemented ashy levels (still in course of excavation). The detritus filling this face was very mixed, comprising large to medium gauge crushed stone, without any soil matrix. The fill presented clear gaps and was discontinuous. Over the course of time it suffered settling and collapse, the latter possibly the cause of the stratigraphic discontinuity between the two sectors of the excavation area. Large fragments of carbonised wood were recovered from immediately on top of the gravel fill, below the lenses of charcoal that were perhaps cemented by the calcinated limestone amid the detritus.

As things stand, there appear to be quarrying phases that predate the funerary structures in the area in front of the Buca di Spaccasasso, in correspondence with the amphitheatre created in the limestone bedrock. The last of these phases originated the cemented ashy layers, attached to working areas constituted by very fine gravel mixed with black, charcoally soil containing chips and fragments of rachitic green stone hammer stones (East Front). This extraction phase may have come to an end following the collapse of the overhanging rock that the activity itself had created during the course of time. The detachment of stone masses would have rendered the rock face vertical and the collapsed masses themselves were then used to form the border of the funerary structure’s ossuary that was created when the cave went out of use. The face uncovered this season (South Front) represented an earlier extraction phase, filled with mixed and unstable detritus, which formed the floor and work surface in the later mining phases. It remains to be established whether the reclamation and filling of the South Front, the earliest, occurred after the mining undertaken in the shaft known to date as the Buca di Spaccasasso and the small adjacent cave in the southernmost portion of the limestone bedrock. These two cavities, which the evidence indicates were man-made for mining activities, cannot be easily inserted within the sequence of mining phases that are being identified. In fact, both cavities are isolated stratigraphically from the rest of the mining evidence due to clandestine interventions.
It is possible that mining in the Buca and adjacent cavity date to an intermediate phase with respect to the South Front, the earliest, and the West Front, the latest. Their chronological collocation in this intermediate phase of mining activity remains, at present, hypothetical.

For the important funerary evidence excavated during previous campaigns, the Poggio di Spaccassaso has been inserted into the PRIN MIUR 2010-11 (3 years – prot.2010EL8TXP) Project “EPIC – Eredità biologica e culturale della popolazione italiana centro-meridionale lungo 30 mila anni” (thirty thousand years of the biological and cultural inheritance of the central-southern Italian population), coordinated by Prof. Olga Rickards, for genetic, paleo-nutritional analyses and radiometric dating.