Friday, March 8, 2013

165 - Are they similar?

(By Filipa Rodrigues,,)

When I first saw the image of the Perdigões geophysics, I was digging the Porto Torrão (Ferreira do Alentejo, Beja) ditched enclosures as part of the mitigation work related to the setup of an irrigation component of the Alqueva reservoir (EDIA, SA). This work brought together a number of archaeological consultancies (Crivarque, Neoépica and Archeoestudos).

A monumental double ditch system, which encloses an estimated area of 70 ha, was identified during this work.

In one of the sectors whose excavation took place under my responsibility (Sector 3 East), the architecture of these monumental structures can be briefly described as:

  1. Outer Ditch (Ditch II) → Width - 12m; Depth – 6m; Profile – tending to a V-shape;
  2. Inner Ditch (Ditch I) → Width – 8,5m; Depth – 5,50m; Profile – tending to a U-shape.

The Sector 3 East excavation revealed parallel and concentric ditches ca. 30m apart. Dimensions aside, these features are similar to most known ditched enclosures; however the Porto Torrão double ditch system is distinct in one important aspect: the existence, every 25 m, of small tunnels interconnecting both ditches.

Therefore, I interpret these ditches as a single feature, not as two separate and independent constructions, one meant to fulfill a common purpose. Subsequently, but within the time range of the Copper Age, these features’ original function became obsolete and they were filled-up. Their original purpose and the reasons behind their deactivation in Copper Age times remain open questions

In the area of the site under my responsibility it was not possible fully to excavate these tunnels; in the area under the responsibility of the Neoépica consultancy (whom I thank, and Raquel Santos especially so, for the information), the connection of the ditches by tunnels has been confirmed.

In aerial photography, the layout of the Porto Torrão features reminds the images returned by the Perdigões geophysics:

So, the question that I have for now is: are they similar?

You can also see an excavation video here:

1 comment:

  1. Porto Torrão is an outstanding context. This particular circumstance indeed reminds the Perdigões geophysical results for the outside ditches, connected by perpendicular features. We do not know yet, at Perdigões, what these features are, but the area of intervention of the Málaga University team (that is collaborating in the global program of research of Perdigões) interferes with these realities. So, maybe this year we have some answers about them.
    My doubt, at the moment, is if we may considerer the two ditches as parts of a same general feature at the beginning. It seems clear (at least at Porto Torrão by the moment) that they were connected by these “tunnels” at a certain moment. But is there stratigraphyc and chronological evidence that demonstrate that all these features were initially built as “one feature”? Or are they the result of several and additional moments of construction?
    I am aware that, at the moment, and for several reasons, these questions must wait a little longer to be answered. But whatever is the answer(s), one thing is certain: these structures are amazing and raze a lot of empirical and theoretical questions of most importance to the interpretation of these sites (in a specific moment of their lives) and of the societies and minds behind them.