Late Neolithic ditch (left) and Chalcolithic ditch (right)
Location: Ferreira do Alentejo municipality, Beja district, Alentejo, South Portugal)
Chronology: Late Neolithic and Chalcolithic
Bibliographic references: (Arnaud, 1993; Valera & Filipe, 2004; Valera, 2010; Valera et.al. in press)
Porto Torrão is known as a large Chalcolithic site since the eighties of the last century (Arnaud, 1983), but only in 2002 it became clear it corresponded to a complex set of ditched enclosures.
The excavations that detected the presence of ditches for the first time were conducted in a context of emergency Archaeology (Valera & Filipe, 2004), related to the building of a high voltage electricity line. The excavation of the area of one of the pillars of the line revealed two parallel ditches, separated only by eight meters (a space where some pits were also identified and excavated).
Although the ditches were close to each other, they were from different chronologies. The inner one was filled almost to the top by sediments with Late Neolithic materials and the outer one with materials from Chalcolithic, with the presence of Bell Beaker almost from the beginning of sedimentation.
The Late Neolithic ditch is 3,5 meters wide and 3 meters deep and the Chalcolithic one 5,9 meters wide and 3,4 meters deep. In the first one, some pits were identified inside the ditch, opened along the filling sediments.
More recently, again in a context of emergency Archaeology, other ditches were identified, and several necropolis of tholoi and hypogea were detected around the enclosures (Valera, 2010; Valera et al., in press). The limits and the design of the enclosures and necropolis are not yet known, but the general image points to a large complex and one of the biggest of Iberia.
Peripheral necropolis of tholoi and hypogea (a particular structure is a ditch function as an atrium of access to several the funerary chambers through passages excavated in the ditch wall. Inside the ditch, several pavements of circulation were identified). (Image published in Valera, in press,in, Michael Kunst, Roland Gauβ, Martin Bartelheim eds., Vom Erz zum Kupferartefakt. Metallurgie des 3. Jahrtausends in Zambujal und im Südwesten der Iberischen Halbinsel, DAI, Madrid.)