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)

_1)The site of Su Forru de is Sinzurreddus_ Following the initial investigations in the area outside of the great fissure of the rhyolithic _duomo_ in which the rock shelter of _Su Forru de is Sinzureddus_ opens, during the years 2005-2010 the excavation continued in sector E, in correspondence with the area covered by the shelter and in that immediately in front of its entrance. Below a massive horizon of collapse structured by large slabs that had fractured away from the vault and laying in between them, a large number of human bones belonging to various individuals of diverse sex and age (infants, sub-adults and adults) emerged on the internal surface of cavity “A”. A number of pottery fragments in secondary deposition following the disturbance of the occupation levels determined by ancient collapses, dated to the later middle Neolithic horizon of San Ciriaco di Terralba, that is the second half of the 5th millennium cal BC. In correspondence with the entrance to cavity “A” there was a high concentration of obsidian flakes mixed with, and in between, the slabs that had flaked from the rock face and in association with anthropological remains. Some of the bone finds showed clear traces of burning, which had occurred both in the presence and absence of the flesh. In close proximity to this area was a concentration of lithic and bone elements, the vertical juxtaposition of several slabs indicated the existence of a lithic cist, now completely destroyed by the collapses. Also present were several pedunculated obsidian arrow heads, fragments of plain pottery and two metal spiral rings attesting a possible later burial, dating to the early Copper Age. Radio carbon dating carried out on charcoal samples collected from various stratigraphic units excavated within the area of cavity “A” attests the presence of repeated and discontinuous episodes of occupation on the site. These can be dated to diverse phases of the Copper Age, early and middle Bronze Age, Iron Age I, the late Punic and Roman Republican periods, the late medieval and modern periods as far as the mid 20th century. The incoherent distribution of the samples in relation to the stratigraphic sequence confirms the substantial disturbance to the deposits that was documented by the excavation. _2)The site of Sennixeddu_ The mapping was completed of the vast workshop for the reduction of obsidian in the locality of _Sennixeddu_, characterised by a scatter of waste products over a surface of 20 ha. At present the investigation is concentrating on defining the flaking method and the chronology for the workshop’s activity, through the excavation of a small trench (Test 3), dug in 2007. The preliminary results of the technological analysis show at least two main phases of the exploitation of this raw material. The first period, beginning in the middle Neolithic B (second half of the 5th millennium cal BC) and lasting until the early Copper Age (end of the 4th millenium), essentially undertook the rough-hewing the blocks and the first shaping of the polyhedral nucleuses destined for regional and inter-regional circulation. The second, datable to within the middle-recent Bronze Age, seemed finalised towards the production of geometric microliths beginning with Janus type flakes which are particularly widespread in Sardinian nuraghic contexts.