The excavation was undertaken in an area characterised by a rock shelter in the locality of Su Forru de is Sinzureddus, following a series of systematic surveys which localised a greater distribution of obsidian in the area, both geological and in the form of artefacts. The area is formed by a series of terraces; the last one constituted by a layer of lava flow. One of the fractures, over 20 m deep, which transversely crosses the lava flow, brought to light an oblong cavity inside which obsidian cores, retouched flakes and waste material were found. In 2003 work revealed that there had been a partially collapse of the shelter’s vault; in 2004 excavations continued in the area of a collapsed mass of rock which had previously been demolished. Work was interrupted when a horizon of large blocks was reached extending over the entire surface of the open-air excavation, west of the area where the demolished collapse had rested. In 2005, the excavation carried out towards the eastern edge of the fracture produced numerous obsidian elements in secondary deposition, inside charcoal layers linked to burning activity and clay artefacts of historic date. At the same time the rocks from the collapse which were uncovered in 2004 were surveyed, the demolition of which revealed a layer made up of numerous obsidian flakes and human bones crushed during the collapse.
At the end of the excavation outside the cavity several tracts of the level on which the vault collapse rested or of a phase including the great block from the central sector of the fracture had been reached. Inside the cavity a generalised phase of crumbling of the slabs of rock which constitute the upper interface of the deposit caused by the collapse of the rock was identified. The radiometric examination of the human bones will help with the dating. An indication of prehistoric occupation of the shelter in the middle Bronze Age is provided by the find of a geometric microlith on a Janus flake, from the nuragic period (middle-recent Bronze Age) in the eastern sector of the fracture. (MiBAC)